id = =) eq Zz = c= =) ‘ga 1O@ATIONY re ce ; ae " mh Bis + ‘ : AI “ ho She : ; Pe f i % , as ui 7 Pees i _ y ‘ ‘ ' ; hr > me ¢ 9 ne | g f é ¥ ‘ J 4 ¢ a <) y 7 rm | #, ee 4 7 ‘ : t sd / ™ =) a4 wi Oe Fd : “o «t HEATING AND VENTILATION, fT he BUILDINGS. i / a trandlated by N.Clifferd Ricker. da ; vee a UNIVERSITY BLUS PRINT. ae aces ~ (aa | HEATING AND VENTILATION. a im —THTRODUCTION, a ie The warming and ventilation cf occupied piMat aes contin- ually assumes greater importance in construction, is much more he Ged” ample and complete in public buildings than formerly, and ap- paratus for this~ purpese has even been introduced into private 35 dances, where nething of the kind was once to be found, or which, mod ern ideas of comfort requires the most ‘care- “Among. the applica tone of Heat to the industrial processes, to manu fact uring and metallurgy, the wamming and ventilation of; Inhabited vai 1dinge. forms but a small portion of a much ; yay rete it subject has now pace tec fk ah abs general etn el ales fodtab lished by the il- lustrious. Peclet will alwyas form the basts of new applicattom | tions; © ut practically, it igs necessary to show with considera— ble detail, how these principles permit the determination of ' the. dimensions, capacity, a and fuel required, for the numerous . forms apparatus now in use. Each constructor has devised “methods: pone special proces ses for arranging his apparatus, its ust flues, Aaa it is ele ae otanehd to combine roid = ee ons |, Now. very Memnatiest ed id £CO mes ela ood in: oe a complexity, a8 required in practice, and this simplicity should be the greater, because in future this know- ledge. should be familiar to every one. It ig not only indic- pensable to the special constructor, but to the Architeet or Enginee who directs the work, must frequently guide and ccn- trol. the constructor; ‘they mus t prepare the site for hin, and arrange the. walls and fleors beforehand fcr the recepticn of the. apparatus for warming and ventilation. Between them should exist an understanding and ecocperation, requiring both to possess a knowledge cf principles, as weil as of the preces~ ses. of ‘execution. To attain this end ts the obiéct of the present work. As it is mainly. intended for practical use, it has not been thought sufficient . ‘to merely give the formlae and computations reqi- red in the exeesubion of a preject, but care has a been taken to aceornpany these with numerous applications, se:as to thoroughly explain thetr meaning. These calculations are usually quite lengthy and-> ORE Ce Os eo that they have been arranged in graphical tables, where the specialist will find the results that he needs, already compu - -ted: each graphical table is also accompanied by examples, . . eed : FEATING AND VENTILATION, <5 actekeealy explaining ite use. Renee, most specialists may consider the computations as ‘demonstrations, and directly emplcy the graphica! tables, at onee obtaining the solutions of the questicns, with which Ni ey marks this distinetion, each Chapter is divided arts: one theoretical, in which is given the calcula- Ne their. applications; the cther centain- ing. Uemeties! results of these formulae, and the zraphica! tables, with examples ef the problems connected therewith. Such ts. the method empleyed thrcughout, in order te study the ditt rent ‘parts, Bengzixzit: constituting the principal div- isions | ‘ef this work; the Construction anc Arrangement eof Fire- apparently a very simple subject, though really most and Aityie? understcod: Heating by Hot Air; Heating by Hot. Water: by Cas; | then Natura! Ventilatien: Ven- nan Suomen and in Winter, by the different medes of on known; | yard | Mea Ck Mechanical Ventilation, now a pylon: a ke th e sta y of these questions Tea easily acceseib& a a handled, is the end, here desired to attain. Ke oe necessary to condense the work considerably, - adapt it for use as a eta text-book for class inst- rae is ees accomplished by a greater eoncise- ¥ ii, ty laountas The metrical system or Weraniel measures and temperatures will be. employed throughout, unless otherwise noted. Tables for changing from this to the ordinary American sys- tem or vice yore will be found at the end of the work. )) ei to. the text. are indicated vy enclosure within 3 Yys re vee Gq ¢ % | -e “ oc HEATING AND VENTILATION, Mo tiagelf CENSRAL PRINCIPLES. : PRELIMINARY CONCTPT IONS. LFFUSION OF HUA, | mit. 5, ~-- The Calorie is that quantity of heat re- Air ce to raise the temperature cf 1 kilo or 1 titre of water 1 degree Centigrade. 10 calories will raise the temperature of 10 kilos of water 1 degree C., or the same thing, that of Te aye: of water 10 beak iti ee ealorie -- 3.9683 American 1é temper kit Cs 4) 48 the “Pots a of cheabatdstanea . | Ratha bi Peay eee yh Oe POs Marble, Cha? 0. 212 : Baan 8 Alt ah Steel OL 107 € Oe, ORI.” |) Tin 0, 057 10, 1938 0° Wrought, Tron O. 114 0. 031 Zine O. O86 HO; 034 Water 1. 000 0. 237 Nitrogen Oa O, 214 | Oxygen Q, 218 iba Steam, Waeer Vapor 0.475 Cees heass fiers’ ee are for gases under constant sure yi. @., the gas expands freely as it is heated, its nh rematning. equal to that of the atmosphere. For gases having a@ constant. volume, the tensien of the gas: increases with the. tenderature, and its spectf¢c heat ts found to be much less, than. if under constant pressure, beeause in that Case, no ‘part of the heat is employed in producing the mechan- teal work required fot the expansion of the gas. Radiant Heat, --- Heat is transmitted through a vacuum like light; some subatances step {t, just as opaque bodies obstruct light, while other substances siti te the passage cf heat, as transparent bedies do that of light. ‘Prom a hot pedy, placed in free apace, heat is slowly radia ted into space, and the oedy accordingly cools. Two oy ee heated bedies rautually emit and reeesive heat rays frem each other; ene may receive mere than it emits, and ‘thue become hotter;. Radiant heat may proceed from bodtes not visibly hea- ie just as light rays may frequently be invisible te the #ye, though manifested by chemical] phenomsna. Heat ig transtaitted in a. vacuum only by radiation, but is Pe, * ta =) = = ne race Leg GE RS i eH Soy * HEATING AND VENTILATION, oe Patri aiennls diffused in air; the air is- heated by centact with the het bedy, prises, and. is: replaced. by other layefs, which ‘eh eated fn thetr turn, while the heated air transporte the ee Lt eg a perbiea bis ogee Beat. ia then dif- sect an eanat Aankyed of polished 12. gees power of ) is Sapat tm- ower inereases, win is Ei. to perdactiy perished,” ‘the heat This ee ‘the inter- yi des, Pays. et ee fall on selid, ‘Tigutd,. or gaseous bod - ¥ Reflected, another portion is ragi- erg ag wht es a last portion,’ if the body a ently ee ey ees beabealg lt whrough ae body. _Gon@ectebility. » 4 on, a ‘solid, aa oe. gaseous i er stratum of a body | peceiva heat on one side, whieh is, atffused in the layer, an d eter ‘through: DE ME hie 3%, Let Q -- quantity fet heat entering and, leaving the ‘layer, per untt of time and unit ‘of surface. — Let t vamperature of the surface th contac Ae pe = Ae. 1. SHRARING AND VENTILATION. | e. ee t -- temperature of the surface in contact with the sources of heat. “the heat leaves the body. Let are Poe & of the layer between the two surfaces. ; Then S| -=- k(t - 8!) eg e 4 oa ef heay per awe vs of surface is evidently pre per | 8 as terence ef. the Pon eran Unes ef the Pea be N. deg. and e as Tt. pu we have GQ - ko i papell, cf calories per unit of area and unit cf ye wiht pass through a layer of the substanme | nm. kis. alse ‘the coe iitetent of Ab ce angen dd of the "Nl Peelet ane Dosprecs, the values of k are as > a 4 . ey i a ant 12 28 Marble 0. 48 « iaiarelevay | ‘ a 0.23 Wrought Iron 7. Sb Lea 4 om Ae en al eee as Boe ae val ne. @. ‘4e@ eB er k are very smatl for liquids, if they are net ; agitated, as heat ean then hardly pass downwards in a liquid. (his. is alse. true for haamilans though these are always agitated _ by heating. ha sider a body as receiving heat from a medium threugh cone rd heat hoses, A ray the opposite surface intc by Temperature of Eve. hot gases er ai 0am i og temperature of the air to be warmed. het. haws oa ecpfficient depending on the nature of the het gases, or of the scurce cf heat. Let. hho --) a ceetficient depending on the nature of the air, Sor ier, the medium to be heated. ‘Then h(o - We -- quantity ef heat entering the body. 1 ae hi (9! - 1) -- quantity of heat leaving it. These have ace demonstrated by experiment. . Or, the quantity of heat entering is preporticnal to the difference of. the temperatures cf the hot gases and of the surface ef the body in contact therewith; the quantity leaving is preporticnal to the differences cf the temperatures of the cpposite surface and of the air to be warmed. © Hence, after the regime is once established, the quantities entering and Dupes are igh ae and we have: - 4 omeremen et. ti ks ‘temperature of the parallel surface, frem which th HEATING AND VENTILATION. tee QO == k(t. = t')) ---:h(O -— t) -- nh’ co!’ — tt’). fice et ree The application ef these formulae will ve made, when the pas— Sage of heat threugh walls or metallic plates ha. ecnsidered, and graphical tales will be given, which obviate the need of all eomputaticons. - ) VAPORIZATTON. / ‘i Latent leat of VaporiZaticn. ---(The latent heat cf vaport- @aticon. is the heat absorbed by a. fluid tn passing from the liquid te the gasecus state, without ehange cf temperature). This te all ‘expended in the mechanical work of widely separa- ng t @ molecules of the liquid, and | i overcoming the pres- thé air on its surface. — gous phenomena occur when a substance passes from the to the liquid state; vy kile ef tee absorving 79.2 calo- le melting, retaining a constant temperature cf OC. © cf water abscrvs 536 to 537 calories tn passing from uid to the gaseous state at 100. After al} the water @en changed into steam, {ta temperature begins to rise. Cae temperature of the Water at the cenmencement. tt! -- required temperature. cf the steam — “Then 608. B+ .305 t ~ @ -- number cf calories required te preduce } ‘Kile cf steam at bre I kile of water at 9’. (4 BPFECT OF HEAT AND PRESSURE. ) 3 “ Sxpansion cf a Body. --- A dcedy expcesed to heat expands. bet Liz; length ef a sclid bar. — . Let t -- {ncreage in the temperature cf the bar. Let k -- a constant coafficient depending on sthe nature of the matertal. | | Value cf k. a ae Cast Tron 3 - 0000111 a Copper | - 90001 26 - : | Wreught tron, / - OO00170 «@ . OOOOISO. ™hen Lk t -- increase in the length of the bar. Increase in volume of a liquid or gas follews a similar Jaw. Let V -- volume ef the liquid or gas. Let t -- increase in its temperature. Let a -- a Odd nas bone ecefficient, Bensibly ~- , 900367 for all gases. Then Vit a--- inereabe in volume of a liquid. Or .00367 Vt --.inerease tn vcelume of a faS. The value. of the eierribiont a is mich smaller for liquide., . than foriwases, and is not constant for water, since the grea- est density of water occurs at 4 °. Variation of the Volume with the Pressure. --- The volume, cf a gas varges wath inversely with the pressure to which it ta subj ected} in accordance with Mariettse’s law. eos ee HEATING AND VENTILATION, 8. “ret E and 12 be two different pressures het Vand V’ the the two corresponding volumes of the zac. Fhen Vi -- Fy whence VY) -- VH. Vv Rt a Variation of Volume with? Temperature and Pressure. --- For an inerease of temperature t, thé expansion -- a Vt, the new @ being -- Vil * at). Vo -- volurie of the gas at 0. | wviae-~ V, (Pat). <- ite velume at t, assuming a -- ) be constant. the voluns Y at oO cf a gas,whose volume is V eer . we io . cat A x os ve My G2 | 3s Wand weet the same weight of gas, at tempera- pee rete reese ges W and H*, we have: — #! cl + mt" ) . We C1 at) sures may be expressed tn atmospheres, in kilos éntimerre, or in height of a er of water or Lhe weight of a “eubie decimetre or titre express i ‘in kilos; that of water ¢ing 1 kilo, 1 litre of water weighing 1 kile The densities of gases being very small, are usually expres- s6d with reference tc air. Or more simply, the weight of a m. @. of the gas ts. directly introduced in practical caleula- tions, Stating the temperature and pressure of the gas. At the temperature of G’and under the norm]! pressure of } atmosphere, the weight of l mec. of each of the principal gas- es t& as relies: : : Cres Air 1.293 kil. fllum. gas. average 0. ‘BBO Carbonie Acid.» | Paves Nitrogen I. 288 Carbonic Oxide ). 267 Oxygen 1. 430 Hydrogen . 6. O90 The denstty with reference to air is found by dividing the iven weights cf the gas by 1. 203. v s vie ee * ~ “ 4%: Le ots SS ae a Seis TAR HEATING AND VENTILATION. given weight of the gas by 1. 283. Let p -- weight of 1 me. of a gas at 0, and under Let t -- new temperature of the same gas under same a 2 ee -- weight of 1 mc. of the zas new temperature i : Cae pressure alao varies from H,, the weight per ot ae BES ' Dalene!) HC] PS chal Pap BY Cle abe || ‘Volume and Weight of Steam. --- Steam cendenses below 100, ut thecretically, cns May compute the volums and weight off steam at any temperature, sinee these bear a certain ration te the similar values fer air, the weight of water pvapor being OLE PS > 8 that of afr under similar ecnditicnsa of tempera- ture and pressure. D>: Henee, under pressure FE! and at temperature t, the weight of } tay 4 ef ‘steam -- > -- .622 17 (1. 293) - 4 ape 6 aoe ‘ He(] + at) — H.i(l] +* at) | vile ia, Ah ~ ACT at): . 8 A (LES RX 1. 383). ‘BOA Tn considering the uses cof steam, graphical tables will be Siveut which eae sot these formulae and dispense with computa-~ tions. he HEATING AND VENTILATION, — TO. - ; COMBUSTION. — . % : ies is a, combination of the fuel wi th oxygen. the iret, Deere corpo. oxide in case ‘of ing onplels Bagiowes ticn, er earbonie acid if the combustien be eemplete; the ter forms water vaper. The necessary oxygen is furnt shed the air he sp@e Detal quantity ef heat is preduced by combustion St. Pou ecartonic. cxide, a seccnd one then producing ni 3s ag ae comp Lee comboustion predue ed carbonic ‘the available ee BE of heas result eae ade peer tey to whether the water bserbed by fit. Woes: pag sing from the iqhia: to the 6. " Hence, in stating the. quantity of heat furnish ef each kind ef fuel practically emplcyed, a dis- 1 16 required, aecerding te whether the water ia ecnden , if the fuel is capable cf preducing water. leries preduced by Puel. Condensed. Not ecnd. forming carbonic oxide. a 2470. 2470. Spice Bh ge ghon ic acid, ) _. £060, BOEO 4 Ae | 34480 29000 carbonic acid 3400. 2400 eent water 2150 1700 cent water 307 6) 2660. . 4385 5. 40 46. 7 1€0. EEEO 207 5. 1646, | ma | a Ser Oe uking? 39 40) “Ligntte, a | 6300. 5100. eres ‘le@ano or not caking 7220. “FOTO. ane fat er caking ) £300 ®200 DL atih baste } ; £000. 7850 wh. Coke’ foe ae 7360. 7 360. Petroleum oe 7 | 160180. © 480. Tlluminating deal ch 11300 10260. Be THEORETICAL FOr AULAE. Sompcsition of: Air, --- Byy velume, 1 me. cf air is com- emas of: | oak aie ‘Oxygen’ ee O. 2050 m. c. ao Nitrogen | | 0.788 Water Vaper | 0. 0128 Carbonic Acid O. OOOB By weight, 1 kile ofa ‘ + > aes — Pa Se ak ve . HEATING AND VENTILATION, re ofp weight, 1 kilo cf air is composed ef: Ree a ORME Os Kite. ee iereg ena ye) bua! Hic 0. 763 : “Mater Vapor G:008 OO, STE NPS: Rt MOR Olt ees) hs on | O: MSs ; ae Yat: 2 wee YPQ ie oy Hae 0, O10 i Garbonie Aetd. 0,901 Quantity of Air required fer Combuaticn. --- The quantity ‘ofjatr dived fcr the combustion cf varicus elements being Known, tie easy te deduce therefrom the quantity required by a Compannd substance, tf its nature and compogiticn be known. Knowing the quantity of oxygen required, we may determine the quantity cf air necesgary tef furnish the oxygen, from the ‘cempesition given above. Thig would be the quantity of air eupolutely necessary, theorerically, for complete combustion. » T Kile of pune carbon requires 9.6 mc. of air at OF or Al. 68 kt loa, ; ae I Wile ct pure hydregen requires 28.8 m.c. of air at O, or 34, 06 Kilees oe” 2 | Carbon and hydregen are the principlf@ slements cf combusti- oleae, producing carbonte acid and water. In case of ineomplee Comousticn of carbon, reeognized by the blue colcr cf the fl aw » Carbonic oxide is produced. In this @ase, 1 kile of pure Carbon only reqlires 4.6 mc. or 8.220 kiles of atr. _) Appiteation, --- By means cf the preceding data, {t is easy te determine the quantity ef air required fer the ecmbustion Ta fuel, For wood, ordinarily seasoned, its cempesition being: Carbon O, 380 Hydrogen QO. O42 Oxygen O. 264 Hygrometric water 0. 300 Ashes s O. O14 The earben réaquires .35 X ©.6 me. cf air. Phe weod contains .042 kile of hyGregen, as well as some ox- Veyn, which direct)y combines with the hydrogen, independently bi the air. 6 parts oxygen and 1 part hydrégen ferm water. fence, the .294 kile cf oxygen will combine with -294 4-6 -- O37 hydrogen, leaving .O045 — .037 -- .OO8 kilo of fpes hyd ro- Ben, which requires .005 x 28.8 -- .140 me. of air for its eombustion. Therefore, ae 1 Kile of woed requires for the conbusticn of itr 4 yer Lahey [ae 4th Sie pean a | BEATING AnD Ven LAT ion” ny es eee ee: drogen about 3.5 mc. of ais. this. “quantity ry- 8 nature, compesttion(and dryness) of the wocd. ree cae alr nb paged yeaah required, assuming - Oe @ most. ‘perfect furnaces, the quantity be- ert ee seen hereafter. The example given | sian es Wo(l-tatyy a ii ‘by complete combustion, dina o t of the Yeen const ; hence, the volume cf 3 a products of the decent len of carbon equals that. of ‘the air used, at the same temperature. | D ktlo! of free hydrogen. preduces © kilecs of water by combus- f the fumeremperature ef the smoke be less than 100} this. water remains biquid and has a volume of only .O09 m.c. y Ube its temperature exceeds 100, it becemes eteam, and the vol- ume Oe I kflo ef steam being 1-886. mc. at 100, ite volume at any. temperature ‘above 100 ts found as prey lous] y indicated. The volume of this eteam is to be added to that ef the air hashes for cembustion. — ‘The censtituent water, produced by the direct SeXkoR union ot the hydrogen and oxygen of the fuel, or the hygrometric wa- rer, ‘existing as ion: in ‘the fuel, Lis eboliaes steam independent - ly ef, the atr, ; i ‘Application. --* Port Fic of wood, the constitusnt water 27 333 Kio, and the hggeometri¢e water -- .390 kilo; theér gum is) Fess RiTo; whose. olume | “tos 1. 698 -- 1.076 mc | 90; or 1.220 me. at 150. \ - Wood ecntains .005 kilo of free pisauen. Gio combines with the oxygen cf the air, producing .005 X @ -- .0465 kilo cf water, whose volume -- .045 X 1.686 -- .O76 me. at 100° To this must be added the volume ef the air, used in its combus - “tion, -- .005 X 28.8 -- .144 mc. at 100, @r .188 me. at 150° ‘The xolume of the products ef the écmbuation of feee hydrcogen vis then .264 mc. at 100 cr .298 mec. at 150° A whfey of wocd contains » 35 kilo of carbon, which requires .35 X %.6 me. ef air at 15; the volume of the preducts ef ecm- gs ton being equal | to. that. of the air consumed, this volume 2s 4.37 mc.’ at 100, or 4.94 mc. at 150: | / Hence, the entire volume -~- 4.37 + 1.34 -- 5.7] me. at 100° Yor 6.458 mec. at 160: | ” BEATING AND VENTILATION. 13 ‘to! 10d, the. ee wane of therair and of the prod- - 3 but above 100% the st “ay i f tire Of thé air need. F the mixed gaseous preducts of com- + Ate: weight -- prot of the oxygen Xo: S26 kilo. “6. O10 a a Tou: an in of temperat ee eye - Hoy: the nitregen ab- sorbs .925 | Vg -= . 2287(t — @) calories; the carben- ie acid 0 t 380 X .214f¢t —- 6) -- .0813(t — 9) caleries. (Or, in % combustion, the carbenie cxide absorbs . 426 X. 246 ( 1. 20534% — 0) calories. ) me _ Frem , ‘the water absorbve -O1(€37 - ©) calories, then 5 OR! Oh 475 (t — 106) -- ,O0O475(t ~. 100) calories, from 100 te t The gum of all these quantities equals the tetal quantity of heat absorbed by 1 me. cf the hot gases, and practically -- 0 -317(t = 8) $+ 5,78 calories. Or, it. -- .317 *+4 1, 1f Oo -- 16 o rben requires ©.6 mc. of air for {ta combust ton Poducts of ecmbusticn will absorb about 3 t 4+ 10 RY “The combust tole, is pipe hydrogen. By the sSamé means as before, we find that for ! mc. ef the products of cembustion: the nttrogen abserbs .2257(t ~ 9) cal- ertes; the earbonic acid absorbs .000214(t — 9) calories; (this ts” enly found in the air); the water vapor absorbs . 3131637 —" 8) to become Bteam, and afterwards .1487(t — Q), Making the total sensibly -- .375 t # 177.3 calories, if O=1é& Bach kilo of hydrogen requiring 28.8 me. ef air for its per fect combustten, it follows that its products absorb 10.8 t 4 S109 calories. J. AN excess cover the minimum volume of air is supplied te the fuel. | The weight cf this exeess per mc. -- 1.214 ites at an av- erage temperature of 15° Therefore 1 mc. absorbs 1.214 X ~-235(t —- 9) -- .28856(t — 9): or, taking 9 at 15, it absorbs -29 t+ 4,38 calortes. : 0 _ REAPING AND VENTILATION. aie a The fuel contains water. | : Bach kilo @f water absorbs 637 ~ 0 Calcrias to become steam, on .476(t — 103) mere to attain the temperature t. If @ igs 1 kilo abserbs a‘ total of 674.5 +..475 t calories. ake a fuel eomposed of various elements, for example 6 composition being: Carbo : 0. 350 kile. BL oe a : 0. 042 Ri ss 0, 284 Le aah 0, 300 h shown that .633 kile cf constisuent was formed, and that an excess cf . 00! the eembustion of the earbon abdserh . ries per xk ile. on Lee ting frcm the combustion ef the hydregen a>- B alories per kile -- 6180 calories. ‘esulttg from the hygremetric and conatituent wa- ‘574.8 4+ 47.8 -- 622 calerias per ktlo. total quanttty of heat absorbed is: brbon, .350 % 310 -- , 108.5 caleries. ee hydrogen, .005 X 6180 -- 30.9 har, a G33 K 622 o< 393.7 eae a ts Pere Ga ee 633.1 if twice the minimum volume of air be sugplied to the fuel, othe excess net consumed --- 3.5 mc. per kilo cf wood, which | Would absorb 24.85 X 3.5 -- 8¢. 27 calories, making a total of 620 caleries received by this excess and the preducts ef come astiene Es (PRACTICAL RESULTS. | . Graphical Tables. --- From the preceding, it is evident that very complex Calculattons are required for determining on volume of the products of combustien, and the quantity of -a@bserbed by them. These results have therefore been ar- ged in the graphical form, as in Tables 1, 2 and 3. able | servee for determining volumes of products of com)- -uetion. The horizontal scale gives the temperature of the smoke, and the vertical one, the volumes of the products of combustion in mc. | 3 | Tables 2 and 3 give the quantity of heat absorbed by the products of combustion, for the fuels in common use. The air used is assumed to be taken at 15° The horizontal scale is one of }emperatures; the vertical seale gives the quantities of heat in calories. , | Applicattons. --- Example 1. --- 1 kile of woed is burned, Containing 30 per cent water; required the volume of the smoke | taken at 100? | i : \ | "HEATING AND VENT LLAPTON. ane On Table 1 bt tow. a vertical threugh 108 up. to the inclined } sod: containing 30 per cent water; a horizontal throy through “hig ota gives Bbout 5.8 mc. at the side. | ! le: a ma conditions; required the quantity of S abe orbed “smoke. On Table a fol inet vertical through 100. to the ihelined dine for ‘woods a herizontal through this point gives about (635) calories on. the vertical scale... | oats any yey ef: air be supplied, for example 10 mc. | we a pyf Tabl ble a, that at a temperature of 100, this atr ab- lorfes per m.c,, or 250. calories ik all. reak fn theinelined lines at 100 is due to ik of the fuel into steam at that point.) uired. Marie - ‘The mintmurn. volume of air is ae oe shown for carbon’ ' the volume caf iol. as its temperature is oe de evans ihe. a a volume of air required, for the ecmbustion wh l kilo of ‘wood; by: Table TY, 1t- is found to be about, 3.8m €. at 16," 6n.3.4 mic. at OF / For. wood ecntaining : try. “ ‘should obtain 2.36 me. instead of the ~(CPORMULAZ FOR AMERICAN UNITS. ) oe eH FORMULA FOR QUAN? IY OF ESAT ‘PRODUCED. One 1s: ef thefu fuel ts taken. American untts.. a ae. ee per eent of carbon in the fuel. . ‘4 a Eee hoes per cent of hydrogen in the fuel. oo Let ++ per cent of oxygen in the fuel. Then oo ah ghee 78 -- number of heat units pre- duced by combustion cf 1 z& lb cf the fuel. Table of calorificp powers of Fuels. American units. Vyd rogen - 862032 heat unites. Carbon forming carb. oxide 4451}. Carbon forming carb. acid 14544. ? - Graphite : 14040 ' Aleoho] . . ; 1G449 — - Sulphur ; 4033 ‘Wax | 18693 Olive ot! 18785 , Coke from gas -works 12600 to 13500 Tahbark #000 Wood dried at 300 PF. 6300 Wood , ordinary dryness 8 400 Charcoal 10800 Illuminating Gas 3058 percubic fect aco. a ¢ a3) ¢ tet ites wre bios a — a = pas iat att oa? Ss FE 4 nnd gee a SS Se ae + Migs Ae = i oe ie bsa00: per. ky eee oe ee 108430 per gallon. unit ‘is the Basted ef heat ‘required to ‘otied Tb ef water | degree Fahrenheit.” (ae ORE a fant oe sf *y : Pabehesc. gone tinek: ‘poce tvs 5 times this dia! wield a ausuttsy is: evidently most economical, which wt!l= oh FOR PRODUCTS OP COMBUS? 10N, VOLUEE. i: ons 1a of fuee is burned. - ie oe ae een ef carbon in’ tite fuel. cent of hydrogen in the fuel. cent of oxygent in the fuel. cent of water, in the fuel. cent of nitrogen in the fuel. volume of air to bé supplied to the fusl. Ve -- 183, 8% ¢ + 456. 09(h . 0) +2 0: o--+w)1ls.6€1 4+ 11.88 n a . 8 Lee os : aed vel weds ‘ofp products of combustion, taken at O F. e Vt <-- vob Qe. hae ae t )-- velume ef products at t F, | 459 1D. Twice the minimum volume of air supplied. ANG 5 (%. 4+ 134.26 c + 402.78(h — o)\() + 2_ ). yee | 8 452 3. N times the minitnum volume cf air supplied to fuel. Vt neizg yy, & (n - ryf(134. PA ¢ + 402.7 8(h a 2a a se ee OR one 8 452 vis ak ne Td ¥ i ie See Saas HEATING AND VENTILATION. , 17. a TRANSMISSION OF HRAT THROUCH WALLS. _THRORENICAL | FORILAE. eerste 24 Rodndutt rire of the abiela ln of : »f, calcries which pass through a wall ! ‘e metre, per degree col difference between dost iNeed MM 5.095, | f heat abserbed from the warm air by the inner avi 'the’ quantity traversing the wall -- vant! escaping trom the outer surface into external air, _ Ny) Heat passing through the wall. te Mantity of heat passing through a wall of thiekn- 8 8. in a untt cf time. | a4 i i Prove M to be proportional to (t - t’ }y and in- reel reperticnal to oj therefore M -- C(t - t') . . i % = 2. Veat escaping from the wall inte external air. Tats comprises the heat oes by radiation, and by direct contact. ef the air. 1Ot = the teta!l quantity of heat lest per ms. per unit ime, ‘and for a’difference of 1 degree. (t’ - @). oe We quantity of heat! lost by radiaticn. ) ose quantity of heat lost vy contact of air. Then Ol a- Re 3%, OG aie -- difference of temperature; and Fie Q(t? — 9). ae vi iiivdel HéMt) entering bien surface of the wall. This heat ccmes from contact with the warm air, and from ra- Gfation from the inner surfaces of the unexposed walls, whose Temperatures are T. t » Henee; M -- Q(?—~ 12). mliminating t and uv from these three equations, we have: 3 M -- © Q(T — 9) Cv). ‘It 8 isy very small, as in case of the glass in windows, this sensibly ‘becomes: TM -= Q(T Oy (2) , pgs wee e The quantity of heat lost through walls and windows per sec ond {s computed by the two last formulaey multiplying sach val ue of M oy the surface:of the wal) or wincew, adding the twe products. ee ‘Room with all Walls expose? to external Atr. --- No radia- “ = ae y 3 JS a iene < sey Jt Mes a SARA or tes sak andl “tual a - HEATING AND VENT LLAT ION. 3 FS eer eton eecurs | from one wail to ancther, the tnher surfaces of all being at the same temperature. as Then M -- ki (T— t) -- quantity cf heat entering the in- “ner surface of the wall. The quantity traversing. the wall an eseaping irom the outer surface remains as before. a: Bl int ee t ih as _M C3) When © is very small, thig sensibly becomes: The heat Icst: yeu or the walls is found by formula £3); an that escaping through windows by formula (4). Hol low Walla. --- Let the wall contain an air space betwee two walle, @ being the thickness of each wall. ~ Let 7 and 7 =-- temperatures of the wall surfaces on inner and outer sides of the atr space. Let e’ -+- thiekness of a solid wall »whichwould replace the air space, having the same effect. The quantity of heat passing through such a wall would sen- sibly e- Ct; +7}. The value of e’ will be determined by the equation O(7 - mg) = OC « ae): ips a the heat passing throug the wall differs little Tae | C7 BT) whence e -- 0 ge Q Hence, the hollow wall may be replaced by a sclid one, whese thickness -- & eee’ -- 2e7C_ ies Q , By gio deine 2 e+. for e in equations (1) and (2),4 we obtain the following equations. For a single wall only, exposed tc external air: M-- CQ(T— 6) . 3C+2Q 82 For all walls exposed to externa) air: M TC k’ CC O(T — 9) CO 2k') +20 k' « When several air spaces alternate with the walle, the trans mission ofheat diminishes as their number itnereases. With | air spaces, the quantity of heat is reduced toe one-half the quantity passing through a solid wall of equal thickness. Partitions of hollow bricks are excellent fer preventing the passage cf heat. Values of C, k and k’. --- These have been found by expe! iment; those of the two first depend on the natures of the terial; that cf k’ igs independent of the nature of fal, depending only on the form of the wal}. ‘ 7a Mesh ‘ M eles 7& to, 3, 48 3.80 ie a. ordinary. ‘s 7TOtto. 2, OF Pie a ts: «Limestone, _ dias: re de ao ; 3. 60 i ype ura, Me NOS to 0.82 3.80 ges cotta 0.51 to 0,69 3. 60 fy acc. to grain. 0.083 to 0.170 3.80 uae Oo2) 3. ¢0 wie BO es : 2.91 . 0. Q40 Nhe 3. 85 Se ee AD: Ores 3. 65 ‘2, O40 fas ee a! Wy J | . PE DOO NE: 'O, 46 to 3. 368 So oe bi elias ag a | : Pon, ° “weough aera? Sages bea 0.45 to 3. 3@ Tren, « cast Tee sae OG) Gor 3.17 to 3.3 Fhne PR BOM fe. OOD ass 0. 24 eo ot SO ae > 14.000. ° | 0. 24 (eRpar | | fo aon ee 0. 1€ Charcoal, Powdered DOR 3. 42 oe ames a Coke, powdered METBOR 3.42 For. vertical Plane walls, k' varies from 240 for walls |! m. “high, to. J.20 for walle 20 m high. In practical @ases, its “value may be taren as 2.09 withcut great error. Por cylindrical walls, axis horiscntal, Kk’ varies from 2.62 fer diameters of .05 m, to 218, for diameters cf .40 m. iy ‘eylindrica] walls, axis vertical], k' varices invefsely By heir heights; from 3.85 fcr walla Beri ae diameters of . O25 and: heights of . BO m, to 210 fer diameters cf. .5O m. and : eights ef 19 m é PRACTICAL. RESULTS: bes ooiteat ton of Formulae. --- Bxanple 1. --- A’ reem is 5 m. “Xm and 3. m, High, with 2 windows, each 1.2m X 2.5 m ay 15. Rape 0. | Only one wal! expos ed. Required the quan- ae Cc -- ic 60-41. £6 -- < Be. | : | For the glass; k -- 2.91; Kt Ge 2,21: Q -- “ 12. By formula (2); 230.4 calories pass ‘ehvough tae windows. BY formila eye. ROR. OE calories pass through the wall, as- i. ‘Fence, the tote) loss. of heak 619. 38 calories. : Example 2. --- Room with all walls exposed: & % 10m and ta th high, with 1@ m.s. glass surface in windows; walls .6O nm. thick. Valuds of G, k and kK’ are sensibly equal to those of ¢ ee Ls ™~ kg: HEATING AND VENTILATION, | 20 the preceding prohiem. | By formula (3), 2012 calories pass through the walls. By formula (4), 348 calcrias pase through the windows. The total ipsa of heat therefore -- 2360 calories. Ceilings and Floors. --- If the rooms: above and below the : a one considered,” are at the came temperature, no heat wil! be lost through the floor and ceiling. Then, if only one wall is expesed, formulae (1), and (2) a applicable; if all walls are exposed, the true results are a little greater than those given by formulae (3) and (4}, on account of radiation to the walls from the flcor and ceiling, approximating those of formulae (1) and (2). If the rcoms above and velow are nct warmed, the floor an ceiling must be considered as externa) exposed surfaces. Cenerally, as an average, it is assumed tRet half as much h@at passes threugh floors and ceilings as through the 7 superficial area of walls. The preceding formulae are to taken as bases of approximate estimates, made in accordance with the Speeial arrangement cf the réom to be warmed. In churches paved with stone, and with valuts of masonry ce ered by wooden roofs, the heat lost through the vanuts is ver smaii and may bé neglected, while it is assumed that two-thi thivas as much passes through the payed floor, as through equal area cf the walls. , GRAPRICAL TABLES. Tables 4 and 6 have been arranged to abbreviate t! mination of the heagz lost through the walls. The firs the less in calories, when only one wall is exposed: the sec ond, when all walls are sxposed,. The horizcntal scales zi the difference of the temperatures of the internal’ and exter- nal atr. | mpplications. --- Example 1. --- Rcom 8X & m. and 3 m. high. &xpesed wall surface -- 12 me., and .60 m thick; glass surface -- 6 ms.; difference of temperatures of the ai ~ + oe Table 4, follow a vertical threugh LE up to incli- ned Tike for a ‘stone wall .50 m thick: a horizontal through this intersection gives on the vertical about 24 calories pe: M86 For 12m.sa. -- 12 X 24 -- 288 ealories. @ vertical for IB also intersects the oblique lines for S@ on a horizontal through 37.5 caleries per m.s.; Lhere- @6 X 37.5 -- 225 calertes are lost through the alasa. The total loss of heat then -- 225 } 288 :- $13 caloriss. Example 6. --- Room exposed on all sides. 8 X 10m and me high; glass surface -- 1€@ ms.; wall surface -- 128 m.s. difference of témperatures -- 16° [In the same way, by Table 5, we find 18.1 calories fost | Me 8. Of the wall, and 128 KX 18.1! -- 1933 calories totaly lo 4 ; , My ad Y 4 ; ae Ag 4 3) “My, Oe pains Mie ha) Nei Rd ie P) aa - ERATING AND VENTILATION, ey tor the glase, about 22 calories per me., making 16 X 22 -- “ealeries in all, . 77 1933 4 352 -- 2265 calories per hour. alls are exposed, we should apply Table 4, ta- exposed wall surface and 16 ma, of exposed obtaining 1340 calories for the wall and 600 making @ total of 1940 he ti ed instead of pee be made for loss through the floor. condags Glazed conservatory 6 X 10 Mm, average one Bide SNS a wall .30 m. thick. ecg Bltde the “a s.; thato of the ahi -- £8460 -- not: the wall -- 40 Mm. 8. Pe the wall loses 24 calories per me., or 40 XK 24 - 960. calories. : hho glass” loses 28.5 Schiea: per mea., or 4220 in all. , The, fleor loses half as much as the wall per ma., 12 cale- nies per ms., making 720 calories. “ The. total. loss -- 960 + 4220 +720 -- 5900 calories per hour 7 eae 4, =-- Room with but one’wall exposed. 5 X 3m and high; hollow wall composed of two brick walls, each . 24 Deitel with an air-space; glass also doubled. “An Table 4, ‘follow the vertical through 15 up to the oblique - line correspond ing to two brick walls of .24 m..thick, obtain- ing 11.2 ealortes per ms., making 11.2 X 12 -~ 138 calories (for the wall. _ Also, for the double glass, we find 26 calories per ms. mmaking 6 X 26 --+ 15¢ calories for the glass. The fotar® - - 291 instead of 500 calvriés found in Example 1. wh Hast vanced by Respiration. --- In case the room is cccu- ‘pied by a considerable number of persons, the heat produced by their respiration should be deducted from the quantity lost “through the walls, etc. Each persong produces by respiration an average of 80 calc- ries per hour. Heat produced by Lighting. --- In strongly lighted rooms, - principally cecupied at night, like theatres, it is necessary to take accound of the heat produced by the lights. ; l kilo of illuminating sas preduces about 117000 calories. 1 mc. of illuminating gas, of density .55, preduces 7150. / Thus, 4 burners, each consuming 200 litres per hour, produce 8720 iegnirecl wae 7 bee wes oe mt Eine, re weet > re - ong ke = lie | HEATING AND VENTILATION, Uae. an \tire of petroleum produces 8400 calories. | ay litre of illuminating ot1 produces & 2900 calories. ee ordinary. lamp produces 300 to 400 calories. per hour. eee ea bf poco lee produces about EON9 calories. 7 ea iven data. i the heat peek lighting can be. est ima- ted from that lost through the walls, so as to he quantity required in winter for maintaining a pes in the room. — this is a aon t ean, ef ven- * ~. HEATING AND’ VENT LLATTION. LAWS OF FLOW OF CASSS AND STEAM. ORIFICER IN A THIN WALL. I | PRES SSURES. =-- If a gas, under a certain pres- selec in & racsiver, and an opening be mad@ in the lepressure. | This pressure may be Ai eres spheres, i.¢., by the ratto of the pres - to the norma! baromet ric pressure, by the hee of Water or mercury, or by the height of a » compressed gas, having the s weight. general fermula is V -- |/2 g P. ise velocity of discharge of the gas in m. per ration of gravity -- 9. 8082. "eneé between the internal and external pressures, height of a column ef the compressed gas. convenient in practice to express P in centime- “(Pika emda of mercury, grammes, or fractions wi deme Poageway pressure. “normal barometric pressure. "These three eran eros may be express ed in any units , all ef he eas kind. a ek of the gas, with reference to sir. i Anaramenid of the scan. Water, mercury, ete., which this density being with res (L- eesffict ont et expansion of gases -- . 003807. iid temperature of the compressed gas. Pa aouien to the law of expansion of gases, and to 6 ce law, the weight of the column P of the Bas, at the temperatu t and under the pressure H, per ms. of surface, -- eae is Poa we Rak Feat) ae kilo being the waight of 1 m.c. of air. . tothe equa! weight of a column of water, which measures the moving feree HE - h, -- l0OO(H— h) kilos. In ease the hdcmupd be measured by a colum cof water, the wetghts being equal, we have: Noa Bea Be ~ 10004 (H — h) Py HEATING AND VENTILATION. Or, expressed in atmos pheres: fea P ad Ws. 10330(H ~ h) . od +31) ha ThorasereyP pr Oy (we hy) bat i Baty / Or; P -% 10330 4 | a 5 d Bheereide’ that Hoa pean - 1330 -- 7946 hat in alle ag 28K0013 i. Pan TEAC ( H = hyd bans. ' ef , 4 ov since only the ratio of tok el enters inte ‘pression, “the unit employed for measwring these pres met modify the values. Substituting this value of R and. the numerical valu the @quation for the theoretical velocity V, we final V -- 395,/(H — hy¢l + at | \ Hd For air, of density 1.00 with reference to air, the Aeal velocity is: Vo o> 395) (B= ae + at) For {1 lurninatin g Vi += B33 For steam at 100° assumed to be . 622; Yo -% BO} Bdduiaed Veloctty. --- A stream of fluid discharg an OPifice in a thin wall is not cylindrical, but e¢ after leaving the crifice, afterwards expanding anew. Let © -- actual discharge in volume cf a gas per sac through an orifice of area s, the gas having the sal ture and pressure as that in the receiver. Then thie discharge is not represented by Vs, but equation: Q-- KV s. K being a coefficient of censtant value, -- .@5f for gases, wien H - h is small. bet ¥ -- a reduced velocity, such that v's -- Q@.-- k actual discharge. Evidently, vy -- KY. Discharge in Volume. --- In measuring the volume cf it 18 necessary to take account cf beth its tem wt ppressure, its volume varying with these. THe @exDression © -- k V s is only avplieable to t the receixer, at the temperature t and under the p! lf the volume after escaping be required, und h, TATING AND VenTtLATTON. Ba Sey 6 sreduee the gas fo the temperature 0 C., and the Bric | Pressure H,, we must employ the formula: et OO bs ih is very small. -- .65 only while H. -:h doee io a 1 M100 of an aihaenhera. But this slight part w cenataerstie velocity tc the gas. Since ; 80 slightly, Q, Q’ and Q' are nearls equal. “i ans ae variations. - NRE eve ‘ he denoity of the gas, with reference to that of a1. -~- If P -- height eof a colum of the ccm ‘ whose height -- the motive ferce, which imparts the velocity V, these two quantities are connscted | ation V --/2 g P, as previously stated. 0 This velocity would be produced, were it not for the ecntras tion of one. stream. oo Ge ~"eoefficient of reduction gf to the ap? velocity. - actual velocity. he ii t @len 7 tn KAY, i Ae aeduct ton of the velocity may be said to reault from a | teduction of the motive foree P by resistances, contractions, Bisa) ge! the velocity may also be said to be dus to a pressure | less than P, connected with this velocity by the relation | ce. mee ess similar to that connecting the tnecretical ve- locity and vie initial pressure in the receive. From these two equations, we may sastiy obtain: ey, aaa DSU ale hn = FY eh, - 1} Ae TRE ay _, Then Pry ~ 1) is the tess of pressure. . Discharge of Steam. --- [t has already been stated that, fcr a shight excess of pressure, k is constant and -- ..66, fer gases in general. é OREATING AND VENTILATION. 26. ments prove that steam does net. behBre absolutely properly s0- called, though these are ineompléte. that, if neo: account be taken cf the eondensed 3 Gontained in steam, this fellows ‘exactly the as the gases, only making k -- .54 instead of .@5. modification, | the formulae already established may Tal RR | apie 0, B08 8 Vv me H (1 # at) 18 Lani ‘the same figures as the mean Sh ah pois This be- the ceorre#w ponding volume at the temperatures and eseure in the receiver are known. The reduction of this vol Oo > to the temperature of 0. C. and the norma! pressure, is made by the formulae already given fcr Q’ and Q'.. at xample for Air. --- ) ~- »03383 m. expressed in a column of water. -= 10,33 m. of water. 6a, Loe: diameter, and 8 -- eB -- area of ‘the or- Pau ie Ace, aes 10,33 + .03383 -- 10, 368 em {lat} -- 1.05% ie “Wiee- 287|/.03383 X 1.086 -- 15.05 m. ee i 10. 36323 | . ae Yb. Of A ~0002 -- .003 mc. -- Q -- discharge in volume eer second. - og ey: wetght; *"p -+ 18. 06 as TQU3803-X. Tok 2002 = = YO0G3s7 kilo. LOe 33 X21 O68 ae Illuminating Gas, same conditions, --- * yey i eae aD, > Fo ca “Sai oy . HEATING AND VENTILAT IO} yxes 345 - 03383 X 1. OBB .--. BO, 20. m. 10. 36383 Qu 20.2 X .002 -- .004 me per second. ‘P. =. 20.2 X 10.36383 X .715 X .0002 -- .0027 10. 33% TS. O55 | ‘For Steam, t being about 100° ¢, oie ae ere 270 Bans A Lese7 18. G4 m. ae | 10. 36383 La. 18.04 va 0002 -- .0036 mc. : EE he pean Xx 1038383 x. 808 xX .O0002 -- .02) kilo. ae Cee dhs eg Meal 387 ‘ Yad Layee and steam. (The ratio. (H = h)-H -- motive pressure, is found on the herizontal. scale, and the, reduced or mean velocity, on the ae vertical scale. ie this. bt eevee the temperature ef the escaping gas is assu- te be Tf it be.t, the velecities given by the Table 8 YN ‘maltiplied byl + at. Sineé the values ofl + at and 7 ‘+at are frequently ‘employed {n: computations in Heating and Ventilation, Oraphical Tadvles 7 and © have been arranged for determining their values without computationg. But, if the temperature be not very high, thie correction may be omitted, directly employing the values giveny by Table &. - Bxample 1, --- Take iia eee 1, already solved by calcula- pI eas | Then (H~ h)-H oe 00328. Fol low &® vertical through . 00326 on the horizontal scale, up to the curve for air, and a hcrizontal through the intersec - tiongives: < ‘acout 14.75 m. at the left, -- velecity for the tom- perature 0. But t -- 15. By Table 7, we findVl Fat -- & 1,027. (since %. 027 is given ‘on the wevttcs! sea2le by a horizeon- tal through the intersection of the line for /1 ¥ at and a weriice! through 182 } Hence, 14.76 X 1.027 -- 15.14 m. -- true velocity. The volume and. weight of gas discharged are found, as pre- vteusly obtained by computaticn. ’Bxample 2 -- Required the pressire, which would cause 14.64 mc. of A valid dan tet gas to be discharged through an cr- ie: Of area --=..0002 om. 8., .tn. I: hour. | Then 14.54 43600 --. 00404 ni.c. per second, and .00404 +> . 0002 -- 20.2 mes diacharged per second, per m.s. of area of orifice, alac -- Velocity ef discharge. | Fol low a horizontal through 20.2, taken on the vertical scale, to the Line fer gas; a vertical through this intersec- tion gives about .0083 on the horizental scale. ee Vics. » HEATING AND VENTILATION, ” 28, maence, It = h -- 2.-_h +-,,0033; h_-- 1 ~ .0033 -- . 9967; : H «a H H : péince h --. 10.33, H must -~ 10.33 4.9967 -- 10.364 m. [Example 3. --- Réquired the area of an crifice discharg zing 2038 m.c. of steam pie second, H being -- 1.0035 atmospheres, nd h .l atmosphere. (H - h) +-H -= about .0033. : “Table 6, we find the velocity for steam reduced to 0° te bout {5. 70 rie y Table - the reduced pressure resulting from the re- lation vo =+\2 SP! aya : Pee Sait Be accely shewn that P ER whit a eal OS a Ae. ik k P ap =* Jose of pressure, and k -- coefficient of reauct- ] 8 . ion, just sacwn to no longer be’ constant(as for w pressuras Dut Varying with the pressures to which the gas is subject Henes, it becomes necessary to aelect a value for k, corres - ponding to the conditions of discharge. A number of values are given in the Tabie, and intermediate values can be found by me 2 Cd -e > 4 ” ce @imple proportion, with accuracy“fufficiant fer practice. Discharge of Steam. --- The same laws appear to govern the dtecnarge¢s of-gases and steam, and iss velocity of discharge like those of @ases, my be expressed by the formula vyopu= KV2 @ P -- kk V«. But steam has this peculiarity, that for both low and high pressures, the value of k appears to remain constant and -- . 64; we have just seen, that for gases, on the contrary, k » 65 for’ low presseures, decreasing towards .411 as the pres sures increase. APPLICATIONS JFor ALP and Tliuminating Gas. .--— The velocity is obtained by. formula (1), making R -- 250.75, TRE weight cdiacharged per second is feund by the formulae: p -- a Es. ¥ PULoODpiaer Rigs Tale p -- er His , for illuminating gas ee. We Cl $ at) Ho -- norm! pressure in same units as H. Wor Steam. --- The formulae already: establish for tsa M vere _ ene “St dees i RATING AND VENTILATION, under low pressures will be retained. Vo =< 270 \/(H — hj (1 +4 at) H pes~ .809: Hos y ; Hof{l + at) Formilae much more complex are frequently given for steam which are perhaps more tigorously exact; but those here pgiy are sufficiently correct. for Heating and Ventilation. ' From the weight dtecharged, we my easily obtain corresponding to the pressure h, cr to Hj, and tor ature O, by the equations given for Q, Q' and O°. Example for Air. --- required the velocity of air subjected to a pressure of 3,5 atmospheres. Bure -- ] atmosphere; temperature t -- | Then H - h--..7143; 1 4eat +- 19174: 4 -- { ! Example for Bteam.’--- The steam to be under th puges as the last, external and internal. Steam und: sure of 3.5 atmospheres ts ata enperature of about | Then lade at ~- 1.5138; and v -- 28) m. These exists a constant relation between the tenperatare and pressure of steam. But two cases my cecur, which change the nature of that relation. The steam may remain in contact with water, receiving « the heat pequired to produce boiling: or it may be isolat from the liquid, then becoming suderheated. _ tn the first case, the steam is Saturated, y al the*water possible at its temperature. The special relat! hen extstin€ between that temperature and the elastic p Pf. the steam is very accurately known, from the numerous ery @Xact experiments of Regnault. In the second ease, the isolated steam behaves like a ; bueying Martotte’s law; and that of the exransion of gases musing an ineréase of the vVélocity of discharge. ® special importance in Heating. ~ CRAPHICAL TABLE. For Cag and Steam --- Table 9 is construct anner as the corresponding Table for low pres bo (H = hh) +H is laid off on the horizontal acal pl scale giving the velocities for air and 711: inating ne right verticalseale gives the velocities, for steam ed in the : Ss - 4 ures & ww As befere, the temperature of steam as well as that of 1 B8eS has been reduced to 0, to simplifvthe calculations. e temperature fg t, the tabular velocities multiplied by m+ at -- the actual velocities. The value of ae a found by Table B. For low temperat ~ 6 ¢ : HEAT INC AND VENTILATION, fy ech ae 32. . gonapa) ly unh Coessary, and. we may di neakty employ. the value: gtverr by Table 2. ‘. | % Simplification fer Steam --- When steam ig not superheat & the relation Be@@ween its temperature and pressure heing ,the correction #0P temperature can be made directly. This done by Tabte 10.>. On the lower horizontal scale are the hOr Motive prResaures)> both in atmospheres card hoe the eal scalevstves the actual velocities, without paying any at /tCenbion $6 the temperatures. The upper ane ‘ndad Bcale giv« ‘the temperatures. of the steam corresponding to the pressures Egiven on the lower scales. If onty the temperature of the | Steam is known, it is mot necessary to detérmine its pressure “by means of Reghaults Tables, in order to determine the velc efty, aS this can be directly founc. Bxample I. -- ke the example previcusly computed. F quir read the eaveetis of discharge of air under @ pressure 3.5 atmospheres, anc at — temperature cf 250° External eure liatmosphere, Then (H — h) +H -- .7143. By Table 9, following the -verttea !) through .7143 up to curve for air,a horizontal gives about I888 156.8 m= on vertical scale. . i By Table 6, Vi +at -- 1.39, -for t -- 250. “Then 156.5 X 1.39 -- 218 m -- required velocity. The volume of the compressed gas -- abcut 216 me, ged per m.8. of orifice. This value can be. reduced to the normal pressure by employing the forroulae already Tor Q' and .O*. : The weight of air discharged can be feund by fern viously given. Here H -- 3.6 atmospheres. and h ; Oe at me 18S fe bain Then Pp. -- ; 616 kiles Ss. Cf area. of ‘orifice. - Example 2. --- A réceiver contains the area cf an crifice, such that 28 114 -8team may be discharged per second. > On Table 10, follew a vertical through 140 down +t ang a horizontal threugh the intersection gives abcut 281 at the left, -- veleeity of discharge, and also -- volume charged per ma. of orifice. The area of the ori tice mus % then -- .028-—+-— 281 --.O000l-ms. -- ] square centinetre bigerre that this volume is that of the tick taken tn receiver, not after it has expanded. we might have found by Table 9 the 140, whieh is about 3.5 atmosphe: ig preferable for steam, unless iid be used. hin. ast if it ni of considerable thick- oe ‘the orifice be furnished with short pga) darroee termed ajutages, the. conditicn i by. ar uel tase ion A eee pena: n, st heh “0. 010 0.012 O, 030 ras OTe 'O. aT BOT. Ree : 83 | 83. eae AJ. secds. sgecot * £3 mis : ~ 83 Ss ; wes, 48 previcusly found fer ‘an $i “this: md: Reh increases with the length : wi aye ‘about 3/4 a.) genes dipeng saiueg san a series cof similar exper @ following 100 240 0.010 0. O2% DOB... 6. Q (0.880, 2. 43 4, 85 me 0. BOS) 0.668" yO. 650 0. 630 0. 632. ¢ ee irate 2. eam. S36, nearly the value of k fer discharge Gs & a thin wall. under: similar conditions. k then increéa- -@es with the length of the $jutage, until its length equals Deore diameter; beyond | this, tt slightly sbesdeain Ps oak ‘Practica! Resulte. and Applications. --- Replacing P by xhr ssed ive value expressed in height of a Fag eae of the compre ga8, as previcusly done in case of discharge through a thin wall, we may write; : E For Air: ov -- 395 k& [/(H ~ hj) ¢1].*# at) , | Ta ee For [illuminating Cas: vy -- 633 k\/(H = hy (1+ at) Soa eal ES iy Be oad gp ik ae Se hivicy it ee ee y x [eek tan happy ee RN Oe ALS Somme Be ye? ‘HEATING AND VENTILATI For Steam: (H =H ¥ at ) | ‘These formulas are quite similar to ele previously obtain- -@d and aré to he used {n the same way. The value of k varies with the, Genditions ef the ajutage, and fs to be assumed in Nee With the experimental results previously given. tired, for example, the volume of discharge of air under essure Of two atmospheres, and at the temperature of 100° ‘external pressure being } atmosphere, we have (H - h) +. a. SO. et the ajutage be 2 centim. in diameter and of equd “Tengen, Led «-"1,00, and. k should sensibly -- . 66. Aiea “t Then wi -- 38h x 66 V5 X 1.367 -- 21€ m. CONICAL AJUTAGES. rt » Convergent Ajutages attached to the Receiver. --- Expert - ments for determining k, made in the manner already Weseribed, ‘show that k varies with. the angle of convergence @ as fol lows. These values are greater than for discharge through a thin wall, only becoming the same fer an angle of 180% when. the ajutage disappears, and the cages be- come indetical. The ecnicah (convergent) a oy awce: Aidently increases the discharge. (The opening in the ““amall end of the e ajutage is alwavea to be taken as the Orifice of discharge. ) tf the ajutage has exactly the Aas St ef the centre eec vein, it will not restrict the discharge Hence, Be | @ conical ajutage will diseharge mere than ae orifice in a bain Wall, ora evlindrical ajutaga of the same area. , Angle @: 0° 10% 30. col Gee 200) acl. 180. ee Oo. 83 0. $8 1300 (0,06: 2076. 20.72 0:88 ° 0. GE Convergent Ajutage en the Tnd cf a Pipe. --- If the conver- gent ajutage be placed on the end of a pipe Of equal diameter, like the cap cf a ehit angy ay, Tlue, the values of k area little differen _.--7 as in the follewing table. The values of. k diminish frem 1.90 fer @ -- 0; where the ajutage merely forms a contin Uation of the pipe, until it becomes .€5, when @ becemes 180, Since the ajutage then disappears, or merely forms an ordfice ina thin wall. : . Angle = 0. go &!) JAG, €o.: 80. 200. 1. OO 0.93 ©. 86 ie Ok: ( Oe Ba Oo. 8 Divergent Ajutages. --- When the ajutage has the divergent cone, the ccnditicns cf discharge are aa S| fied. “xperiments give the following results. Sy Ce, tsa ye . poy higgt, “pa rr ere Ew ae at sas ' - : ~n f is r! ee $33 B "HEATING AND VENTILATION. : SCs | ES Le eRe te ee TR. ROO. BO. 1024 1,70 °°2.26 2.46 1.96 1.40 1.30.1. 181108 e Set OS = velocity in the cylindrical portion of the, ajutage; then v -- k V, V being the the- fetical velocity due to the pressure in the receiver. ea Re value of kK ie greater than 1.00,. increa- ~ Bing with the angle up to 7 where {t attains {te faximum value, then diminishing. Beyobd 50° wR sensibly --. 1.00, g0: that ‘the discharge is — not then affectad bf the ajutage. It is produced. by the production ofa slight depres- pressure in the ajutage, which materially increases 4 ity of discharge, pacttcal Results and Applicatio --- Pron the preceding, bece ride that to obtain the’maximim discharge pos - ible, % ny argent, ajutage ‘attached to the receiver should oan ‘opera ef 20 to 30; fer divergent ajutages, an angle cf i efficient. 2 formas for velocity of vWischarge of air, gas, and steam, are the same as for cylindrical ajutages, Since only k changes. according to the ferm of the aiutaze. | Required . the velocity of discharge of air through a cap ter- 4 ing a chimney flue. The angle cf convergence of the cap BOF. temperature of the air -- 100: internal pressure 333 kilos. ‘per square centimetre; externa! pressures -- Kitos | per square pitied ne ae : | hoes Of atria Fi ce6 398 (H = + at) Aibriee | eo arout -80 for an angle ef 30; (H — hye i fs 90029; iat T.3k7. 4 “Then v -- .90 X‘'398 “0025 CPS get ae FEEL. rm. For (i histhating gae or steam, replace 395 in the fermula by 633 or 501, respectively. Less of Dresses. --»= This i@ found. in. exactly the same way a for discharge through a thin wal], and whatever ths atts of ajutage, the loss of pressure -- P - p -- differance between the pressures corresponding to the theoretical! and the actua! pelociti ce. And P -p -- pil ~ }) cage =a = The value of k in this expression will te the game Said usy ay given, according to the form of the ajutage. ~, i‘ ra, ‘ ne oY a. ie Se Wade” HEATING AND VENTILATION, { 38 ly given, according to the forn of the @jutage. GRAPHICAL TABLES. By means of Tables 11 and 12, the velocity, or the pressure corresponcing to the velocity, may bé found without computa- tion. Whatever be the form cf the ajutage, we always have: vy -- KV, V being the theoretical velocity. On Tables 1! and we, curves are drawn, which give the theo- retical velocities for air, illuminating gas, and steam. The first Table is used when (H - h) 4-H does not exceed Oll, cr for low pressures; the second serves for high pres- sures. The tabular velocities correspond to the temperature Tables 13, 14 and 15 give the values of k for cylindrical, (with low prescures. or high pressures exceeding 1 “100 at- mosoheres) and for convergent and divergent ajutases. First find by Table 11 or 12 the value of V suited to the given conditions; then by Table 13, 14, or 18, determine the alue of k tnder similar conditions, and take the product of hese two values. (v -- k V). Hxample 1. --- Required the velecity of discharge of il lum- inating gas under an internal pressure of 1.036 kilos per square centimetre, through a conical convergent ajutage, whose angle -- 30. (H - h)~+-He.. 0048. . By Table 11, follow qa vertical through .0048 up to the curve for illuminating gas; a horizontal through the intersection pives about 36.5 m on the vertical scale, which is the theo- etical velocity V for a temperature Of On Table 15, follow a vertica! through 30 up te the curve for convergent ajutages on pipes, and a horizontal through the intersection gives about .88 on the left vertical scale -- k. Then .8& X 38.5 -- 32.12 m. -- required velocity. Bxample 2. --- Steam, under a pressure of 2 atmospheres, escapes through a cylindrical ajutage .02 m. long and .O! m. in diameter. Required the velocity of its discharge. ( H.- h) +H -- .50. By Table 12, for high pressures, the corresponding theoreti- al velocity -- about 353 m But its temperature -- 120. 6° men its pressure -- 2 atmospheres, as found by Table 10, here the temperatures and corresponding pressures are given. aides as before, multiply this result by |/.1 ¢ wel by Table 8; this thecretical velccity, then - Setaee Ms) DY Table 14) 7K -=). BE, ate L+d-~-- 2. The actual velocity then =< 427 xX. -=- 284 m. Discharge in Volume and Weight. --- es e are given by formulae found for orifices in thin walls. Let s -- area.of the orifice, and Vv -- actual velocity of discharge already found. Then Q <== 8 V -- volume of compressed gas discharged. HEATING AND VENTILATION. | , And Q' -- ay Sa ne of expanded gas discharged, -- Q ah. Also,- Os = QH -- volume of gas at temperature om Fe(1 + at) and under the normal pressure. fo Fo ne Cae Hv’ -- discharge in Pati Mal |) Red + at) HEATING AND VENTILATION . 1 eee Bh iene es 73 Lalas ee FLOW THROUGH PIPES, _ Sy eon Baa The gas or steam escapes from the receiver through a pipe of a certain length. The velocity will vary according to the di- rection of the discharge, the length of the pipe, the varia- tlons of section, changes of direction, etc. These causes of résistance are to be successively studied. ~- SO ABRUPT CONTRACTION, Coefficient of Reduction of Velocity. --- The section of POEL ee ee the pipe may diminish abruptly. This fre- quently occurs in ordinary ducts, and also al- _Ways exists at the origin of the duct, where ~ it leaves the receiver, by which it ig suppl ié@: » Let d’ and d* -- diameters of the larger and , Staller pipes, or the corresponding sides of square pipes. a ie a We have from experiments: oe Bo OL: 20 0. 99 0. 40 050 £O,60 0.70. 0, 80 2. m o| Dig 3 0.04 0.09, 0,16 (0038, 0.3¢ 0.49 0. e4 = eee 0.82 0.83 0,84 0.86 0.88 0.91. 0.94 O- 0063 0.0328 0.0747 0.1344 0.2150 0. 3168 0. 4459 0. BOI1E es 8 K pk! d 0.96 §1,00 \ mz --0. 81 1, 00 mt \t0 o: -- 0, 97 1. 000 k’ --0. '7667,1. 000 : Or, Tet V" -- theoretical} velocity in the smaller pipe, if it were, not preceded by an abrupt change of section. Let v* -- acttal velocity in the same pipe. Then v" -- kV", the values of k being given in the prece- ding table. Velocities in the larger and smaller Pipes. --- Knowing the velocity in the smaller pipe, a n the larger is easily found, since equal volumes of gas must pass through each pipe, after the regime ig once established. Letting s' and s' -- respective sectional areas of the pipes and v', v®, thé corresponding velocities. i i“ Then v's’ -- vigt) or v’ -- sg! » Also, v! -- stv! , ne ea sg! ge) Finally, v'’ -+ k V'e! -- py. sg? The values of kK’, given in the preceding Table, were deduced from the results of exverimente previously given. ixample. --- Required the velocity of flow under a’ pressure SeiAy ae K an HEATING AND VENTILATION. | | 39 of. 003 m of jercury the diameters of the different portions of the pipes being .2 m. and. | m. First. find” the theoretical velocity Vo by the formula, beeen P= B85: \/ ( ) , if the gas ve air at O. For \ ting gas, replace 3° vy 533. aphical Tables 11 and 12 direetig give the value of V Vuptinat ing gas, and steam. : —h) +H -- .00394, and V sensibly -- 24.5 m da! 4b | rom preceding data, k == .86 and k’. --,.215. OWA -- 586 X 24.5 -- 21,07 m, Wins Ss 2ebuK 2405 - 26, 27 mi. eal -~2-- In Table 16, the hor- Rape. bas the Nall uee of gd’ = d': the vertical scale nm of Pea aet thal velocities for large and pee nines. fake the Jast example First find V -- 24.5 by Table 11, # for an excess of pressure -- .003 of mereury: (7 Oates hon .00394. Here d# a+ q! .-',.50. ‘By Graphical Table 16, the coe? ficiant of reduction -- about .22 for the larger, and <-- .&6 for the ‘smaller. 8 : Le lence Ns a OR eek ee Oe: IM. ae eo) Be XN Rae we B27) Mm. aL ea GRADUAL C ONTRACTION. Goetficiont of Reduction of theoretical Velocity. --- If the two portions of the pipe are connec- ted by @ conical or pyramidal portion, the values of the coefficient k will vary ; with the apex angle® as in the following table, : As before, v' -- k V' -- actual veloct- ty in the small pipe, vi being the theo- ee é retical velocity in the same. Angle oO. 10 2 30 AO? 60; 50, 100 140° 18 Kk = 1000.94 0.92 0.80 0.88 0.87 0.86 0.85 0.84 0, 83 Velocities in Large and Small Portions. --- The velocityin Oe aaa EN AN i i APR eae as Bg ad NSA nN Ate aot Ae ce "sale A Di cileceie the large pipe will be found by the equation; v’ -- k V's’ 33 The length of the conical portion remains: indeterminate, for it is not sufficient to know the angleaand one diameter, to deduce generally the ratio s' > s'; or, reciprocally, the an- gle@cannot be determined from the two sections. Hence, it ts necessary in each spec ial case, to daduce the velocity v’ from the velocity yf a general table cannot be given, as in the first cass, which ghall eomprise the coefficient of reduction for the large pipe, and the corresponding coefficient for the small ons TxA mp be. --- Take the sme conditions as in the last casé. —— : HEATING AND VENTILATION, : 40 The diameters are .] and .2m.; angle@-- $0. excess of pres- sure -- .003 m. of mereury. The theoretical velocity -- 24.5, ag previously found. The coefficient for 80°-- about .855. Hence, for the small pipe, V* =- .855 X 24.5 -- 20.95 m., which differs but little fron ‘the result in the first case. The velocity in the larger pari -will be -- y’ -- 20.95 X.10 X .10 -- 5.24 m, : . ¥: mh ie et hee . If the cone were mde longer, making 2-- say 10, we should | find greater differences. Then k -- .£5, and the velocity in | the small pipe -- V" -- 24.50 X .95 -- 23. 27 m. Ne OE Bid And v’ -- 23.27 X .25 -- 6.82 m. | Craphical Table of Results of Experiments. --- Table 17 gives the values of k -- coefficient of reduction for velocity In the saml! pipe, according to the apex anzle of the cone con “necting the two vortions. To find the velocity v*® in the sml} pipe, first obtain the velocity V by means of Tables 11 and 12, according to the val- ues H and h of the internal and external pressures. Bv Table 17, find. the value of k, and the product of the two values -- kV -- v" -- velocity in small pips. To find the velocity v'! in the large pipe, maltiply v* by the ratio ef the s' # BY of the sections of the large and small pipes. © ant Loss of Pressure. --- Let P -- pressure corresponding to the theoretical velocity V" in the relation V* -- V2 ¢ P. And p -- pressure corresponding to velocity v" in the rela- tion v* -<-\2.¢ p. Then P =- p =- loss of pressure, And P -p--V se DCL! ah} -- y¥(l_- 1) , in accor- | : 28 k* Sap Ke dance with the relation v" -- k YV' previously established. This formula is applicable to the two preceding cases. ABRUPT ENLARGEMENT. Reduction of Theoretical Velocity. --- For f ~~" an abrupt increase of section, d’ becomes d* and s’' becomes gs", : From experiments, we obtain the following table The value of k gives the ratio between the ac- tual velocity v’ in the small pipe and the theo- ; tical ae "SCRE MADE ETS, thes trie « ol : a mo. 30° “040° as: 50 0. 60 Boe | om on 0. 18 0.25 ig. 38 am kV) +. CC OE 8 of pressure aoe +003 mh. of mereury; diam | and . 2 Wa a2 t. | al-y elocity v ‘by means ef the known J(H- h) 4-H for air. Other values are to be 325, fo steam or Gene tine gas, as already ah ei Ls + 783 m. ; “whence 5 ie Maas * 0: “eonsequent ly; IN es LTB) ome 7.78 ye In Table 18, the horizontal roe Rate preceding Feta toy oh a --..50, and we find k n is - 32, being the coefficients for the large diameters. - With these values, the velocities eae e any obtained as before. Instead of computing cd, gn A ENLARCEMENT. Hy m experiments wi the angles ones from 0 to 50, the val- Ao eG ete oe FIG RO 30°: 40° 44° BO" 1500. i 70. Be As I. 95 1 BO eT, 30. 1/18" 1 608 71. O8 Die Ne eae, Beyond ‘BO, k, sensibly -- 1.00. eau: Lae velocity y’ in the small pipe is found, after the theoretical velocity V’ in the - same pipe, whieh¥ is deduced from the mov- ing pressure actually existing in that part of the duct. ve «2+ kV’. Velocities in the Large and Small Portions. --- The veloci- ty in the large part -- v' -- yi.g) puff. Knowing v’., v' ts @asily found. § © ' sf” | _ HEATING AND VENTILATION, sey S Je, --- Same conditions as in the last case. . -10m.; da’ -- . 20m; excesa of pressure -- .003 m. of neroury.; angia®-- id Then k --, 1. 60. me e ‘air, V) -- 395 \/.00394 -- 24.5 m . \ Pe ey) ++ 1.60 X 24.5 roeeh (Ae ne oR / : OMe SOUT XK . Ole. -- 9,19 m, | Graphiael Table of Results. 2s. The er te taken on the hert zontal ‘scale of Table 19, and the vertical scale then giv- es the value iOnki oN! ts ‘first found by Tables 11 and 12. | Then k V. => velocity v’ in small pipe. The velocity v" in the large pipe 8 then found vy multiplying ve Dy the ratio be ed of the two sections. Loss of Pressure,--- This differs somewhat from that ee for a reduction of section. It comprises two parts, the lose of pressure when, V becomes v’?, and the loss when v’ becomes v‘ Let Pi --, effective pressure in the small. pipe. . Let. Ee p -- loss of pressure when V becomes v’;. ER@RXRXXMXBXHAXEXKEXE ethen Plo. p'-- sts bo ae . 2 g\k* When v? ‘becomes Viv the corresponding TE greedy p’ becomes v' ‘go we have; 4 - pF RE re tae, mane - As 2¢ Bake Ang ois theses two equations, the total ioe of pressure is found bo: Der OBO = nee gs! kr 2g “Phe last eaualibn is true for bate graduad and abrupt enia- largenents, but the value of k differs in the two cases. BENDS OR CHANGES OF DIRECTION, Numerous exveriments were mad3 by D' Aubusson, Dubuat, and Peclet, to determine the effece of bends on the discharge, | Angular Bends. --- If the angle of deflection is greater than 29, the loss of pressure -- the difference between the moving force P, expressed in height of a column of the gas dis coarse and the pressure p corresponding to the actual veloci + ty v of discharge, and is given by : P- p -- Colts Vv" ae C is found to equal 1.00 for. small pipe and .50 for’ pipes .40 m. in diameter. A practice, an average value for C may be taken at 70 without inconvenience. ; if Rounded Bends. --- If the angle exceads 20, or the bend ic rounded, the values given in the following table are found by experiment. Evidently, as the diameter itnereases, C and the loss of pressure both diminish. Sy HEATING AND VENTILATION. 20° 40° CO ee OST hee 85. ! On. BF -- 0,078 0.158 0.233 -- 0.057 0.111 0.187 FRICTION AGAINS? THE WALLS oF [Stance of Friction and its Effect on Velocity. ecity of gas, ‘: py the but, if the gas passes through a somewliat rt the velocity is reduced by the friction of the NB gas, along the walls of the duct. merous experiments enable us to détermine the resistance periments of Arson, Honore, and Cirard: ne V -=- Pe : in ML * 2g P | 1+ML ” Experiments of Aubusson give: v d. _ @xperiments of Poneelet, and Weisbach give: (i 2aP lag ae ItFATFML A is hera a second numerical coefficient. \ ee These three formulae really differ very little from each other, these variations princitpdlly resulting from different Conditions of the experiments. The second formula’ has finally been adopted as quite sufficiently aceuraté for all practical purposes. 3 The coefficient M hasthe following values, from experiment: noe | Cast Lron Pipés | UA ve— OLB] Lead Popes eae M -- . O24, Wrought Iron Pipes . Me =. ORB Chimney Flues | M -- .O24 to .O80. Average value of M for metallic Pipes -- .024, © Morin’s experiments give much higher values for chimney flues, because their inner surfaces are far from beang as smooth as those of metallie pipes, and they are also coated ' with soot from the smoke, The following values may be taken, according to the cofidi- tion of the flue. : ee Chimneys, hww or recently swept M -- .030, i at mt, “at conn Oe HEATING AND VENTILATION. . Rist) 44 Chimneys in ordinary condition. M -- .O045, Chimneys,, very sooty. a M -- ; 080 “For escaping steam, M-has the same value as for gases, if the velocity of discharge be great: but if this be small, fron experiments, the value of this coefficient appears to increase a8 the velocity diminishes. Thus, fer a velocity of 5 m., Mops =9 938. Ratio of Actual to Theoretical Velocity. We have just seen that v -- But introducing the. value of the theoretical velocity V, we see that yv . V, K being the value of the radical. x This value K of the coefficient of reduction evidently de- pends only on that assigned to M, according to the mature of the walls, and that of the ratio. L+d. | Example. --- [lluminating gas, under a pressure -- .06 m of water, passes through a cast iron pipe 200 m. long and . O08 m. in diameter. Temperature about 02 Required the velocity of flow. O18: | By Table 11, V ig found -- 40.5 m. Forcast iron, M -- .018; L~d -- 200+.05 -- 4000. Then k -- l Pipe Paheht © Oh and v -- .117 X 40.5 -- 4.74 m, 1+ .018 X 4000 This shows how greatly the velocity is reduced by friction. Craphical Table. --- By means of Tables 20 and 21, k can be directly found. The first Pable is for short pipes, when the length does not exceed 500 times the diameter; the second Table being for long pipes. Both Tables are similarly used. The values of Ld are, On, 7 the NAS e eee) scale, and those of k are given on the ‘estes one. On the first Table, curves are given for average ordina- ry pipes, for chimney flues in ordinary condition, and also for very sooty flues. Cenerally, the curve for ordinary flues may be taken for chimney flues. The curves of the second Ta- ble, for long pipes, are for pipes of lead, of wreught iron, and cast iron. Application of the Tables. Example. --- Take the precedin example, in which L+-d -- 4000. Table 21 gives. k -- .117, as previously found. . Taking the value of V from Table 1!1 40.5, we have v -- .117 X 40.5 -- 4.74 m. [f the temperature were t instead of Of this result would equire to be multiplied by il + at, whose valueis given by Table &. Sxample Se --- A chimney flue is 30 m, high and .40 m. diameter. The smoke is at 300° and ‘the externa! air at 0. The mctive pressure P -- a column of-zas_ 30 X .00367 X 300 HEATING AND VENTILATION, 45 about” 33 m high. | ; | fhe theoretical velocity V r- Veg Pan V18. 62 X 335 25. 65 Met te mim JOS tes rate” 75. Taking 75 on the wel ecet | -acale of Table 20, aeeoncins to the curve for M -- .045 for ae LEAD flues, a Bes Shee] through she intersection gives on the warteeet scale -- k. The actual velocity -- v -- PX 25.65 -- 12.16 m. / the flue were very sooty, taking curve for M -- .060, k 375, and v -- .375 X 25,.€5 -- 9.62 m. e f Pressure. --- From 'v, e=).V I , or v -- ee | 1+ML Por Mb Wey occe es oe L ot d asily obtain, pave p gor ---= ML Vy, an expression for loss of pressure. 22.0 eneral Remark on’ Flow by Volume and by Weight. --- In all cases heretofore examined, the general formulae establish- | or discharge, in considering the discharge through a thin wall, ‘are applicable in a general way. an © each preceding case, after finding the actual velocity, we have Q -- s v -- volume at temperature t and pressure HI. , Also, Q' -- QH+h -- volume at temp. t and pressure h. a Finally, Q' =-- Q HH (1+ at) -< volume at temp. O’and Ho, a keg flow in weight -- p -- Hvis : Ho(l + at) Rone rk on the Form cf Section. --- We have heretofore as- sumed the secticn to be circular. If this were not the case, the sees ML+d in the preceding formulae should be modified. “Bet. -- peyimerer, and s -- area cf section. Then NM pL should 6 substituted for ML , M retaining its AS Pay: Pine: The formula then becomes verfectly general, and is applicable to any form of section whatever. For a square section, or a circular section, M Be L ¥ £& de- comes M L~d, “as before. » Hence, a square pipe and a cirpular pipe, ne elds and dia meter are equal, oppose equal frictional resistances to the Passage of the gas; the velocities are therefore equal; but the discharges will be proportional to their sectional areas, er as 1.0000 is to .7854, so that the flow is about L4® more in the square pipe. The formulae and tables previcusly given are applicable in their present form, to square as well as circular pipes, which are the kinds usually emploved. They can be utilized for oth- er forms of section by substituting for d the values of the ratio 4 s+ p, which gives a mean diameter, in a certain sense Remarks on Continuity of Discharge and its Results. -<-< The preceding formulae for velocity do net rigorously give 4 ay Mette, cS Adu ‘ HEATING AND VENT [LAT ION, | | the velocity at all points of the pipe, because the locity: ‘constantly varies from point to potnt. [AL the entrance of the pipe, the resistance to «im ot the gas is sensibly greater than at the outlet, set moving gas must overcome the frictional resistance Of the en- tires duct; the further the gas advances along the) pipe, “the smaller this resistance becomes. Hence, the moving pressure must be greater at the entrance of the pipe than at.the middle greater at the middle than’at the outlet; therefore, eines the density of the gas is alwlfs proportional to the pressure_to which it is subxected, it diminishes from the entra to the outlet, But, as already plated: the volumes of gas ee all to points or sections of the pipe in equal times must be: equal, ‘gince the!discharge is continuous; hence, as the denstty- di- minishes, the velocity must increase in comp@nsation, The tv quantities, density and velocity, are inversely propane anes” If the velocity. v corresponds to a density a, then them densi- ty d' will correspond to a velocity v’’, determined by, the re-. lation ¥ + yv! -- d’ +d. | . Ana lagous observations. apply to the infleence of warfations of temperature. An inerease of temperature diminishes the cen sity, causing an increase of velocity, in the ratio given by . the relation oes Lat.’ vy} 1 + at’ “(The following was accidentally omitted, near the middle page 65). ° No change in velocity at ©C.. The total losa is then greater than necessary, indicating too small a ezcetion, too great a velocity. Second Trial. --- Assuming a section Od, SOT" {s.. 130'ta., with a corresponding veleci ; will be: | : Frieticn. L -- ADs = hl POE Se SHEE GCG f: nnd Pi toda erp : q 5 e Right angle bend. i welwoe e * 3 at Bb nsliah one HEATING AND VENTILATION, . | ' .. FLOW THROUGH DUCTS. PRACTICAL APPLICATIONS. GENERAL FORMULAE. : - Total Loss of Pressure. --- For abrupt reduction of section thé total loss of pressure “n PR. - p-~ (1. -,1)¥"_. | We ean re- ECTS a “ : ke De eo @ coefficient D,; whose value can oe. computed from getuenion of section, the total loss of preseure ee ts ifs =< velocity in the small pipe. en teenient, abrupt or avadial. Pp - a ee A Re, and s’ the section of the aon ke % fi oe ngs yo the corresponding values for the large pipe. &’ may ibe substitueed a coefficient:E or £), according as the enlargement is abrupt or gradual, the oe coefficients being found from the values given pen Gey. v béing the velocity at the bend. ag % For friction, P - p --MLv -- ear 2 Ag a ~ Fy, v being the velocity in 28 that part of the pipe, whcese tw Jength is L, and diameter is d. Several of these resistances ex- mist simultanecusly in any duct, producing a total? loss of pres- erent IDB thersum Of tne separate” ee ee eee ee, eee | . Thus, in the duct here represen- eas “Letting P -- initial pressure in the receiver, we “past t hav the following successive i ia of Cy ae | Contraction at A. Friction, Ist duet. eee! aeibe Rekig maine pet First bend. ; | CX spxX we ; ‘ “sy og seeond bend. . . CO’ Xgs7X vr. anlargement at B. Frietion in enlargement. ~--kLhLe2X ya Ye“ ae Bg. "ontraction at C. e- DK ae oe “ws 6 HEARING AND. VENTILATION. *” oe ae Friction in lasti duet. eee Py > ea tes = PIXE ALy3 , | “Te dy. BS | ag In the second equations, the velocities v’ and v" have been replaced by their equivalents V3 Bs Aa ee These values are yy) -- 8 equivalent, for we have v’ gen V3 Adding these equations, member by member, collecting terms of the samé nature under the sign ae we obtain: Pi ee “| 2D sie S0 ae Shas! as iwi -'R wa and Pe ing the fi §7 s* Be 2g ing the final pressure, iP determines the actual velocity of discharge z at the outlet of the duct, we have : Whence, Vv, —-\'/2 2° Pi -= V\/ ; l+- RR. Mee ae [f the temperature be t' ‘in a portion of the duct, ab a the remainder,: the velocities y’ and alitepe the differe t will be eonhected by the rélation s'v’ (1 + af) -- § ca and consequently, v’ -- y S() Tiat)s, anstead of v' .-- | N( 1 +* at? : Se, instead of simply multiplying D by s, 4s, it must atta ed in that case by 82 1 + aU hm Nay, and wise for _the ether terms. 1A Bh ivoadl The vetocity of ‘te eee at the outlet , ing the sum of the terms s ter the coeificient D, C or £, ete. eR by the square of ther ratio | area of the duct at its outlet, to the [onal area of that part of the duct, where is found the Ak ieaed ton, enlargement, bend, frietion,etc., to which these coefficients are applicable When the duct terminates in an ajutage of conical form, thé. preceding must be added a term of the form M s*_L& simply M, for the section of the outlet is also that of ajutvage or cowl. The value of M is determined from that the eoefficient of reducticn given for a ecnvergent coni ajutage, placed on a pipe. | GRAPHICAL TABLES. These computations are somewhat bridged by the-use of Tables 22 to 20, The vertical scales give the vali C, @tc., which compose the total f. The horizontal scales are: for abruvt changes the, ratios of the difameters, and the ing sections, either Tatto bei 5 g i f changes of sé6cti t WwhnetRer ehel _ HEATING AND VENTILATION. AQ Pee ratio L+«d of the, portion of ‘the pipe con- ey ie fapcitis at enlargements, the value of the ccefficien Hey eas oni apex angle and the ratio of the sect- each ‘of the curves G ciebponda to a a _the vertical scale gives the vat ™ , very. (regular ‘fireplace flue at the Con- _ Servatéire des Arts et des Me- ‘tiers. Two vertical sections oat right angles to @ach other are given in thefigures. ) Firgt compute the secttonal areas’at thé different points of the flue, as insegived in | the figure. Then compute es mean diameter for each section, 2-4 ep, few sections being ‘square; 8 -- area of secticn, p -- ite perimeter. We then haye to successively consider: At B, ana abrupt,contract ion the air entering from the roon, ratio of sections theoretically -- QO, the room. being very. oo in comparison with the Pjue At C, a bend ofabour 60, mea diameter -- .341: Wtio L oa. => about 44, From d'to ¢6,. gradual reduct- ion at. 2 very. sml! angle, Lees ; which may be neglected. From f to g, a reduction, which may be considered abrupt; (tio of sésctions -- about .62. pom d to g, friction, length about 1.70 m., mean diameter 33 m; consider the three parts as one, having thean dimensicn like those of the middle portion; ratio L+d -- 5.10. ‘From g toh, frietion, length 17 m, mean diameter . Tatio L+#d -- about 57. | From h to i, an ajutage, formed by the cowl, with an assumed -- 15° | _ To simplify calculations, the mean diameter from b Log | adtifers little from that of the upper part, being slightly eae rue ne t , a ote Ag S v i NY i 1 -¥ 50 %-- ie HEATING AND VENTILATION. | 5O Take for the entire flue, the general ratio Lwed -- 57 45. 1 + 4.4 -- 6@.5; since the effect of fricticn is slightly exag - gerated, the lower portion of the flue being larger, we wil] take 85 aS the mean value of L++a for the entire flue. Next determine the value of R, representing the eum of these Feststances, cbtaining the values of D, E, GC and F, from the Tables, and in accordance with the preceding explanations; mu! ‘tiply each of these ecosfficients by the square of the rattoof pal Bay Vie, er amas and the area of the outlet orifice, ~*-.038 m.8.),as follows: | Contraction at b- (fO 22). 8, --0. D -- . 45, 04s (Se [= 0027 ty OR Ware ea iets 9 Ohm roe 87 vr aie 2 Bend at ¢. (ho 26). diam. pitta: Ce tw yo eet 0.21928 a Contamet ten at g. (no 22). a. .62) Dp -- Cont rac. at Me. (no 22). Ang. 18. Dio e ae: ace el Coes & Sal vg ok b to I. (no aa Fai Pi s00. fos fy 623 ey Sa gi eb, Total. | Natali Renee, R -- -754, and the Velocity at the outlet -- Oy Shatin a'gh or raat ] a=) 4 7 ONG MR Ge i ag es an : _ To find the velocity at other pobnts, multiply .75 V by the ratio of the sections, as from g to h, we have v -- .75 V xX is O38 see O87) 2-9, aeY.. ORIBOAL GC, ovie- (75 Vo XxX »038 +.150 -- 119 V. - After determining the theorstical velocity V, it ig then ea- ‘Sy to find the actual velocity at each point of the flue. The theoretical velccity depends on the motive pressures, which Must be known: from this pressurs, the velocity can be direct- ly obtained by Tables 11 and 12. ; Haample 2. --- In the last case, let the cap ‘be removed. The term .110, representing the resistance caused by reduc- tion at h thendisappears;. the area cf the ontlet orifice be- comes .O87 instead cf -036; the ratios between the sections are modified, and we have: | i Yea PAtb. 0.45 x [(0.087) + (0. 150)] -- BoLKK O. 153 Weg es URE IO) 087) 4 (0/160) yu-= 3 0. 07 1 ah BO. IB lO. O67) + (0, O87 }*- - i 0. 150 PErom' > toi. 3. 00 K[ (0. O67) ++ (0. oB7)] -- 3. 000 | Boa A; et Total. wiik being -- 3.374, v -- v\/ 1: ~~ 42 V, instead of being Ne 4. 374 -> +75 VY, as when the cap is used; but the former velocity in the upper _ flue =-..31, now -- .48 V, being inereased from .16 tO .28 VY. Henes the eap increases the velocity of emission, VOT Lag otal Phe velocity vy -- V 3. mix then. R es he velocity in the flue uke - The same chimney im- “(46 proved in form, as in the figures. » ZE PS ‘ : i Voted bk aed [i ON. te id ye a Z; .3 > BY Whe diminish nes b fi LZ , , “iixample 3. <= @ Sees MEG Neglecting some slight variations, the es 1 9 2. form is as follows. : ees EN eZ At a, conical ajutage cof about 6 , Ob wee Bo a herming inlet to the flue. Ae oe 4g At b, vend of about 60°, mean diameter \ ieee Hy adour - - 30, sectional area .126. EEE re eee Pom a to ¢, gradual contraction, an- Poh Tan | ane Tele. 5. but already considered as form- F465! ogg’ Ade ee h ical e : d : Bie ing the ecnical entrance of the duct. Fae ye. ‘From a tod, friction, length 1°.85 m AY ee AG mean diameter .30, making L-4 & -- a- Ae AG 3 Re ara a iy g y i ; Se ‘ A fe ZA. Git 9 eA Zag : LA Ba Le : L, AG oy ‘(ne 28). -- ane Oot 70, a7) +e S a, 12b ce 0. O99 Prom. a aca ay (no oy F-39000. 3. 00 (00.0 O67) (OG, G87 3[°+\-3. 000 seo Pee 49 V. 4. 21 Sxa mle fo, --- Take a ies as ordinarily constructed at “principal dimensions 51 208, the present time, ites being as indicated in the figures. We then have: PAT TG AND VGNT 1 LAT UO aia = oe O4VtF) )Mentrac.at Bat. (no 22). D =. 45. 4 (race ey, Lavy Gerd, angle 46% Mic. 264. 1C i-- . 12.92 BL Ls ud. ReduebLAnw 30, @io 23). 0) --. 23. sae AL a vrard: bend, ang. 4 fe (NOS) Cy --. 12 (eb Mrietion 4n Cree part; mean dian. ~ Shp Lal A | Friction inv “an Be ae me Le1§ m.: Together avout 7 87). F -- 3. 30. eye ee 3.764 . SULTS. nf | at, besides the friction, the terms respresenting | enlargements and reductions, make up : 74 in the first case, AAG of .209 in the second, ‘in the third, for chimneys as at present construc- ~~ ie = | nea, this total may generally be assumed -- .50, ae an ar- erage. — Slight variations fromt this doy not materially inflia- -enee the velocity of discharge. ei There fora, making FR? efistance due to friction alone, ae write eae ate tae for ordinary chimney flues. | 150+R ! a Valen in general, the velocity cf discharge can be found by eomputing ‘the resistance due to frictton alone, as previously _Wrdl gated. Without a Jen’ the velocities im the flue and at the outlet “are equal, as their sections are ae, hence 8! -- F, which can be found by Table 27. | ; | mies the last example, find the ratio of length to diameter, : about 72. By the Tadle, F -- RW -- 3.30. Then v -- yl (aes & -- .46 V,a value very closely approximating | that. Peerreuaby tane. provicusly found. Na Rag, DUCTS FOR HOT AIR. 1, Avenehince and Bifurcations. --- Main duct to be cf unt- Ge form section. Let a hot air duct be - -3O t% square, and arran- geh as in the figure, with two secondary ducts al branching off at B and C, Zsp, . the main duct auddividing > Sinto two oGkers & and F at D. . what pressure ts required at A, and what must be the seetio ae | ieee 1 : Le Es ee) 4 ah PY ay eee - ; 1 oo VESATING AND VENTILATION, : Bos “What pressure is required at A, and what must be the séct- SYonat dimensions of the-ducts, go that the branch B my dis- charge at least 30 litres Bey Begone < Ib litres, Z and F gar each: 25 litres. | {11 take account or alt ‘causes of loss of velocity, in practices only friction is usually considered, using milar method, though | this is not always sufficient. | discharge -- 05 litres per second. Section from A to m.s.; the velocity Vo muat then be -- .085 4.090 -- place. Assuming the section of branch B -- he main eae its side Huey -212, and velocity nen ay | oe pres 2c ae wilh P Vie 2g. da Lea -- 67, He oe peiae rhe Jala Aas Ob5 }* the f th Ratio of Hee aie oe wh Ves 26; BY Table 2, EB -- 5 (1. OBS + 19.62 -- about 7013. due to the bend and the contraction at B, By Table 26, 1G ha nearly, wilich gives erte on in ‘the eranen B for a length of 10 m, cae _o pressure -—- F wee g- The ratio Lied -- dea ue) ble -27, the. lesa mL ‘25 X 0. e7°+ 18.68 --. O28, of these. Jogses -- 1080 +. 013 HOT +. O26 -- Lae; jt produce a velocity of 1.67 m.; this pressure cet <= ¥) 4-2 g; therefore, P - .138 -- O, 67+ 18. ee (.138 a 022 ree 18 Me “measured by height , on tha: ioteaaune in the main. duct, ‘being reduced mand abrupt. PEALE Sn a -160 - (¢. 08s O12) -- Sehr bronah el The volume of air pasaing from B to C <- ‘$8 - 30 -- 65 litres . The section is the same as at B, hence AA tam OBB 42. 080 --- 722° m , instead of 1.055 mo. The lcss from friction between B and C -- FV’ --2g. Ratio (bye -- 20, and Table 27 gives F -- .50, Making the loss -- 80K. Ted 19.62 -- .012. Therefere, at the entrance of C, the pressure <- ,068 - .012 -- . 056. Assuming the section of C to be one-fourth that of the main duct: since the Fatig cf the sections is as l to 8-4 ore4-5; gon had loss” o EBV’ 2g -- .17 xX. 722 4-19.62 -- .004. + Bal bye Ceameree. ve Ls es ao nae - A % 2 et = ~ : tat HEATING AND VENTILATION, = B4 othe bend and to contraction -- . 35 X 2722" 9+ thy tien in ‘ditet © The side -- OE m; velocity -- nes Oateenirce -- 15 litres; seeticn -- .0228 i. about . 038. : | duet C. e- ,OO5 +. OOS 4+- ,.038 <= O52, ieaving the outlet -- .056 ~— . 068 -- . 004. G7, as before stated. The pressure requi- i “¢ thi ralecity. <= 87" 18.62 -- ,023. Hence PTs litres w uld not ve Aischarged, with the assumed section of “the divet. |: & hiss AEsume— ‘the section toy be . 09 +3, Mire t oad of Oe EA. and 47. 03) m8. 5 which Fequites: a velocity of Legion m, inetead of «A ane we ba Thee ees by Surust padietl on forg a Ris ‘of 3-4 would -- sg. eh eee 16, 62 -~ .O0OB: loss by the bend -- .009 an Defoe. Toss by. friction for Ld -- 57 would become 1.40 X . 5O* | oa OFS) 82 igh O18, Lastly, the presBure at the outlet would --- - O28.) Now, @ pressure of .O0125 would. preduce a velocity of . 50 th “Henee the required discharge would be amply assured witha pectional area of .O3 mas. . O45 will next égternine ‘the pressure at A, that 20 litres may lischarged through B, estimating the oss of pressure . {8 comprises the loss by friction between A and B fcr a hoof 20m, -- Fv-#2 g; ratio Ltd -- 20 i¢- 30 ; Table ke -- 1.70, and the loss -- 1.70 X 1, O57 42. 19. 82 is he loss. in. Bo must be added to this; ratio bd) -- a- it 59; by the Tavle, F -- 1.28, and the logs -- 1.25 X .@7% Poe! ae SORE.” . 18 total Ioss <> 080 +. eo 4. -108,, instead of .138, pre- ously found by considering all gourees of loss, making a dif ference of nearly 1-3, showing the complete calculation to be hecessary,. as @ perdi: against error in sstimating the pressure oe Admitting the valus just found, the pressure at A must -- ‘the pressure required to produce. the velocity . Cr, a. in -B, ‘Plua the loss of pressure, i.e., -- 674+ 19.824 .108, -- about. 230 m, -- height of a eclumn of wa Pm ait, which meas u~ res the pressures. We obtained .180 by the completes methed. The pressure beyond the branch Bo -- .130 —.080 -- ,QKO -- oviiginal pressure - loss in aaiA duct trom A to B. From B to C, the discharge is 65 litres. The section being OF m8. , the velocity -- .O65 4+-.0f0 -- .[22 m. Compute the pressure at the outlet © to verify that the re- Qiliired discharge of 15 litres {s assured, with section .03 mes ‘From B te C, the ratio L+—d -- 20 for main duct;: F -- .50: tk the less -- .50 Xx (222-19. 82 -- O18. At. the inlet of C, the pressure -- ,OBO —.012 -- .O38 instead of » O56, as obt- ained by exact computations, making & great difference cee Ota gt OF gy rd aes 3 - Le er fates ti ry “HEATING AND. VENTILAT TOW, | | Be Sheer oe frietton in Oye as already computed in the complete op- eration -- Ji 40 X . 5019.62 -- .018, for a discharge of 15 1 EP oey ‘the section being -O3 m,s., the velocity ig .50 m The pressure at. the outlet ¢fc¢ then -= 035 — O18 == » O20, ve ny yond of .50m., @ pressure -- ,50—~ 18. 62 uffice, so that already found is sufficient. ifa pection cf .03 m. is suitable for the bi- eth ‘The dischazge bevweon ie > and D ia 50 litres, 1c ty of «O50 + .Of0 -- . BEE rm. ‘om from C to D -- .50 K bhS 19 -- 008, | : * and F -- .50. The pressure 2 yee precedigs ‘ing the ‘ottureut en only -- LOge 008 -- .030. Velocity dn Cep 025 4. 030 =. Be oes a me because the dis- charge in each duet must be 25 litres. The’ yatiio Ltda 48 making the coefficient -- 1.20, and the loss by friction -- Le) OG 833 4 18. 2) hn Oe But the pressure at the inlet of the dues. only. —- . 030, So that its section must be increased. Assume it so be. OBO. mS. instead of .030 m.s., and the ve- lectty: will ,025 47.050 -- .5O m The ratio Ltd -- sale ‘Foe. about . 90; the loss -- .90 X. BO 4-18 oa <= San i, making the pressure atthe outlet -- .030 —.011 -- .O18. "6 produ a welocity of .50 at the outlet, a terminal pressure of ison, +-J°-€2 or about .128 18 requi red. ‘The secticn is then a lit- thes too: large, and tts side would -- .224 ms., but we piety make it .<22 ms. It was praviously found to be Ae 20 Dab cee ‘Hence,’ for determining the sections cnly, goororimare caleu- lations. are sufficient; but the complets method is often indis- pensable in determining the pressures. The use of the Tables wnakes | the latter about as rapid as the former. Branches and Bifurcations with equal Velocities. Lap ae 88m samme the hot air to pass out of the outists of the ducts B, C, D, -and F, with equal velo- cities, |. m, fer exan one arey Pie. That ig, the air iS to be réegulariv in- | $thye troduced tnto all ths rocms to be warmed. Bifurcating Ducts. --- At the outlet of E or F, the prea- Sure required to produce I m. velocity. -- 1. —#-2 g -- .050. The atde of the section -- .158 m., for its area must -- .O26 mes., the oT 8° being 2b yaw litres, and the velocity Im The ratio L 3d -- about BO. The less by friction in th the duct -- 1:26 X 1. 00 +19, 63 =- . 063. Loss at entrance of duct, from bend, partial contractions, Gtc., == 36 4 1.00 418.62 -- .O17. e section “any logs 2‘ pawn i oo ,, gm «187, a O60 =-- O78 aiwesn Cand D Cat ihe © of duet 62 >> .006; the = “287, anes D nian: Meconea ene .0Z0 —. 006 -- Sty ate | ve te a result, and one of rat Ss Thus for R e peas a0 * :, 00 cae : Woy | | 40. 120 os a gz. - is, 62 es ee gab Det 0.17 Weg Ww ap .82 t | we WoO of gl. sae : | 0. 50 Ue 4 cae) i a | owed 0G! | iar im ¢ 16 losses” between Band Cc. Agent ng the aide cf @ duct between Band @ toh be .30m, its section -- .09 nm. asta 23 gel ais be ‘Aischarge - - 65 litres: the velocity then esides, aia: at ‘the change of secticn at C, the sections are 1 oh one side and | 26 -4-.016 -- .0826 on the other, the side ‘the principal geet. ton gi esha C veing fixed at .26 m. A pineeeeenmeen ie a | jae ds ee Bb BOF ae. iy” ws 0.60 X 0.72% -- 0.013 Lal hie | Poe 1. 62 HAL AE TILATION, 58 8! => 0.083 -- 0. 32; 0.02 X 0,80 _ 0. O13 a* oO. OFO “78. 83 . Taking .80 m. as the mean velccity in the reduced portion, | i.e., in the main duct C D and the branch C; the ratio of the sections being abcut unity, the Icss D by contract ion is quit amall and may be neglected. We have .167 as thé pressure at entrance of B; from B to C. the pressure becomes .187 —.0O13 --,.174. This should be . 16 as previously computed, so that the aaatinind side between B ary C of .30m ta a little too great. Distribution to Several Stcrie --=- Observe that ig the ‘hot air be distributed to several stc ri€s, the computaticns just indicated will remain exactly the same. Whether merely the discharge throug! gach outlet ig regulated, as id the first case, with a duct of uniform s tion; or doth discharge and velocity re regulated, the latter being aga ized at all the outlets, as in the Rei ie ond case, the duct fer the second sto- ry, for example, is computed as in the preceding, so far a8 its juneticn A’ with the main duct. The diameter of the ascend ing duct is. thenso arranged that the computed pressure atA’, reduced by the lesses for the bends A and A’, and by friction between A and A’, shall equal the conputed or essure at A, [t is very imo@ertant to state that if the pressure COPres: ponding to the outlet velocity v, equals v*+—+4-2 g on t} ground floor, on the firgt ftocr it will equal the seen Avanti ty — the height of the story; on the seczond, it is diminished by the height of the two stories, etc. The pressures deternt: ing the discharge are so slight, that their differences, a ting from the slight resistance of the atmosphere te ascensicn exercise a ncetable itnfluenee on the discharge. They faci lit- tate the discharge to the benefit of the 7 : Un detriment of the lower ones. Practical Results. Observation From the preceding ¢ = v mple observation sometimes neglected 7 ue? t A that, whatever duct and its bran pac greater ae: from one point te the next, by at intermediate losses eection, ete. : wr. . HEATING AND VENTILATION, BD | i ehce. if the branches’ Band C are of equal lengths ane i ‘sections, he velocitWmnd discharge will be greater at B than cS a ee ae ere the sect iétisyare ‘qual, but C is longer than B, the dif- : férence of velocities and discharges would increase, Mutat c were. shorter, theee differences would tend to diminish. ‘Now, if ‘the: velocity of discharge be equal for all the bran- oS OY “ete., te ere ele possible, B must either be smal- 9% yp longer than C, and the reult will bea lesser discharge /B than at C, at Crthan at 3, ete. a us, in. cne case, ‘the discharge diminishes, from B to ©, C bbe, oN n the other, they increase.. In passing from A towarde _ the. extremities of the ducts, if one assumes for the ducts suc- | eessively met, ‘discharszes alternately greater and sme!) ler, this. requirement: could be s@Rigfied,as in the case first stud- ted, Dut. ‘at the same time, it would be necessary ‘to vary the sections of the ducts and the velocities of the hot alr in them. The sense in whieh the section should be varied ig inci cated by the observation, that, as one proceeds from thé ,ori- fice, @& each branch should have successively larger sections / to. enable it with equal length, to furnish, equal discharge Wim with those preceding Pt, In practice, as already stated, so as to avoid error, the dimensions obtained by compptations are slightly increas sed; 1% the: definite regulation of the discharges will be facilitated by the use cf valves placed in the main ducts, and by neers ters over the outlets at the temmination of the ducts in the | Pooms to, be warmed. But the use of régistera presupposes an excess of sectional area, since the registera only ete sh “the séctiong and discharges. Hot Air Furnace. --- Assume a hot air furnace arranged as | : in the adjacent figure. The air en- ters at A, passes through the grate and fuel tnto B, descending through the tubes C, which are assumed to be 16 in number, then passing from © inte the flue D. Loss of pressure will result from: ‘Contraction at entranee A; but if this opening be made a conical ajutage this loss is practically annul led. Abrupt change of section in the pas- Saze through the grate and the fudb, i ar pre ae which practically -- 6 v2 2g, ¥ be- a ees ing the velocity of the hot air. From tends, which nay be assumed to ba 5 in number, each degreas. Table 26 shows that for pipes about .25 m. in dia Co => SB D0Ut 635.) if thece yanic > bei a ® : HARING AND VENTILATION. 18) ber, © =- about .35, if these bends are ecnsidered to be roun ded by the spaces B and“B'; if the bends are entirely angular Ce OT OO | | i Feietion in the tubes; from the dimensions indicated, Lf d -- 1. 20 4—. Of e~ 15, and we will assume F .- ~-40, for metallt tudes. Oe al aa Ns eticn in the ducts and the flue; the ratio Led -- Al s-- 26) =5 84,: The coefficient F for flues in ordinary con- “dition, of Lone masonry, -- 3,80. . ? Thesg,losses will then be: Bends “No. 26" 5 X x@2..35 Xv>-- 1.7b x vt hi ee el Re, ee” Bs Crate — Mg, Baie, Xe se ee DR ee a RB a Mrietton, tubes. (No.27). 18 X .40 Xvl-- 7-20 x v don, flue. (No. 27). . oy ae OC y a yee 2g afotal -- 20.757 Bg he velocity has been determined by the formilae for to be given hereafter, the corresponding resistances mown. | receding, we have assumed that no abrupt change of | tion occurred, which should be avcided in the construction, OT the apparatua, a8 the air and smoke should find an equally free Pag@age exerywhere. Besides, since the volume of air Va- Piles at different temperatures, the sections must be enlarged Where it is warmest, so ag +0 produce uniform velocity at al} | Points, obviating ail losses of pressure, excepting from the erate, from bends, and from friction. | PC Vo! | e ASPIRAPING CHIMNTYS. er ae pt Draughts from Several Different | Stories, --- Phe vitiated air is ,. d?awn from two séories A and A’, b: ; Means Of an aspirating chimney. The 1 tempsrature of the air in the rooms gis 15; it ts heated at the lowest 3 point of the duct, passing into the XN chimney at a temperature of 50° Assume the motive pressures at A and A! in accordance with the.given conditions, to be respectively 1.87 and 2.00 m, measured*by a eclumn of warmair. Required the volumes of “air removed. by A and A’. +P y bey eee An Gn “Ro. = Yen First compute the registances in me mot. Let Mes velocity cf discharge in the duct between and F. Then from F to a eee vt oo” a + 2 ee ry a ‘i es i. 7 ‘ Wy? HEATING. AND VENTILATION. bitte F, Then from F to B, we: -gucecessively find; ve ae a +* BS Ce (No. 27) ae SPOR ART ae 0. 50 Roe oo 20} side caplhage: . Pea wee oy Ein =- , 80. es city. there ue th +16 ay or V a | 1+ 50’a war’ 7 oO. bore ts aor ist S, and velocity Vo sown ben | i 1.12 , ear T lee : ae ae ae i Yotal of 3.06 Be . we have assumed no loss to occur in passing the heating# ar pereaae: at. a, and that this apparatue is so arranged , that variations. OP. velocity resulting from increase of temperature Oris ehanges of section, are compensated, producing insignifi cant. reauktxe. losses. Assume a. erating to ba placed at A’, the resistances will P akan’ vet. Mogg ae iced id alee at entrance, Bs nlargement after grating, ratio s/ - S$ Prietion, aa es 1 4. ad. O36 | og Aight aot bend at B. 0.30 ¥ ~S oe He | ae “Potal == 1.83 v>e 2g, letting v’'-- velocity in that Pee “Ro this must be added the loss, when the air leaves the duct A’B’ and enters the main duct, its velccity droppin: ‘from vt to V+#-1.12. The last expression equals the velocity in the part Be, where the temperature is 1B? while in the part & FP, the velocity is V and the temperature is 50°. Then in’ the cool portion, the velocity o- ‘G+ 15 a} - ey Ae ae 1+ 50 a4 Po Vv / When the air passes from the velocity v’ to V’ or #41. 12, 'the loss of pressure gensibly -- that occurring for passage “froma section .35 X .38 with a velocity v', to a eéction . 3b XxX .35 XV’ -+v!, where its velocity is V’. The ratio s’ +s’, -which determines the value of the ccefficient of less of preées- sure will -- v' -+-—V’ or V' vy’, according as an increase or wot n of elbeity occurs AK Snveena the ma in ot . are known, the less of pressure resulting f of velocity can be computed. Let P! represent: vhat lens "assure, for the present. the ducg A B B’, where the velccity -- v, the same sect- yn being: assumed, we ‘find the same coefficients of resistance: from: A cane te which must be added the friction frem B to Bb’; oe 50 v= 2g. OAK ve. Ap before, a g Bog rod : -pesutling from the change of. end sadn deponae on the ratio vor ge bee Se: ay ne or! y eT: “en the, sect ion at ~< . O° y? j RENT vYoR y? (4) his: Ronakvion: estates. haw! the quantity of air received by “the main duct equals the sum of the quantities delivered by the ducts A B and A’B’. ; After passing BY.) the two currénts mingle and take a conmen locity, the pressure becoming uniform. Deducting from 2. 00 he lesses. of [pierce une. from A’ to B’, we have, 2.00 — 1, 83_v2. A Py ) 2 : Likewise, for the duct AB B’, the pressure at B’ is only aueh — 83 33 —P. Hquating the two pressures, we must have; } 43 ee 83. AS rer Be ls A yo—_ (FP? - P) -- 0. And, neglecting the 2g x He bys ‘sligne difference Pr - P, we readily obtain: vXxxxx@xh@xadxixdiv vi-= 4.60 + 1.27 v> (b). fhe two equations (a) and (b) enable us to determine the ve- haiti and vv’, when the velocity VY’ is known. ( First Trial. --- First assume V’ -- 2.10 m., consequently, iN ie 2.37 m The follewing procedure is a guide to the chcice ‘of this assumption. Assumews a mean pressure -- (2.00 + 1.57) “2 -- about 1.80 m at the origin of the stngle duct; secpen that the velocity V is uniform everywhere. Take a mean resis- tanee in the first portion cf the duct, which is supposed to replace A Band A’B’, -- 1.83 + 2.33 V2 -- about 2. 00_Y"; the Be ogee ve a Bug 2g total resistance F as far as the cutlet F -- (2.00 +4 3. ne) V7 : aon | eg The motive pressure diminished by these losses -- I. 80 + 6, 68 Ps Te it must be capabde of preducing the velocity V, and therefore == Vive Be. j - ; “HRATING AND VENTILATION. ie @3. we place » 80 « 5.88 Vo as Vv ev y or .l.80>-- 6.8% V.. | Then ‘aap Be | Be g og 8 a g we have VY" «- according bo abo Fae statements: we have a and (b), we have vv mmier DN ine AD Gay Oe vy -- 1.48 m, and v’ -- ig q ae “From Liss uct A) B) to the Lop here is a. Molamvion of ‘the velocity, having the same a, 3 an abrupt ‘enlargement, where .7& 1a the ratio of the 3,;- Under these conditions, by. Table ao, the eceffi- of Phd loss” of proseuse, o U-h7 she velocity in the sre)— x lor pase tad being 2.72. he, the loss of pressure Zz ety WO, dp / r=, O63. A B BT to the main duct, there ts an accelera- it take the batto of Piss sections | giclee 48 422.10. 2° biter os 22, the meet ttcient of loss of pressure is .11. Vath. the loss of preg- tg) Xx 2. 10% Bg wT el 025. rn Pessure in the duct A'B! then falls to 2.00 — 1.83 XxX 2g 1.063 -- 1.247. Al6@, in duct AB’, it equals 1.? ee eri Af 2¢—.025 -- 1.285, The difference P) - P Yoon Dba 025 -- -038, and is neglected without sensi; changing the results. | We will take the pressure ‘after passing into B’ as a mean of the values just found -- (1.247 4% 1. 285) -& 2 -- 1.208. [% re- Mains to determine if this pressure is capable of producing a velocity Vv -- 37 TM. at the outlet of the flue at F, which “deen verify the assumed velocity V. Pi Logs aie ressure from B’ to FY =- 3.86 Vv. The effective —— ct | : a ‘pregeure at the outlet is then 1.266 ~ 3.88 V. To produce a ee the velocity V’, this difference must be v-. neplacing V by SB 8 its villus a. 37, We must have 1.286 - 3.86 X . 42g. or 1,266 -- 4.88 K 2. a7%¢ 2g. y The value cf the seccnd member is 1.37, gc that the values adopted for V and V’ are a little too large. . Second Trial. --- Assume V in the eool portion cf the duct wo 06.22.00 m. At the outlet for warm air, the velocity is Bi Kl V2 9) 2. 24m, is Top bx °% Ay IIe met are eS ty a >? cers 7 HEATING AND VENTILATION: >. Papebe,,, barn Cama atfons’ (a) and (b), previousty given,,wa lave w +.v' vt aA. BO *& 1. 27 ee therefore, y -= |], 36 ™, and y? to “the main duet, the retardation of the Yo an enlargement ef the sectton: the ra- the enlarged portion -- oO ar Ce be. 20 for coefficient of ines s of pressure. to main duet, there is an acceleration of ‘ he same ettect as a reductton pf section, “tions -- that of the velocities a= 1.35 +- yes a coefficient of .11 by ‘Table 22. penck, AB), the pressure becomes 2, 00 Ph Sap g -- 1.273. Die us at. : he of warm air --2.024 in F, ‘ e@. , oe we Niectseds a2) Koss Bea 2 gg. The value of the sec- eee: ae find “the values now adopted for ateanes that het actual valocity in the first part of -- Vi -- 2.05 m., and in the part where the 2.30m. Therefore, v -- 1.45 m., a the volume of air Resatng through | iis . 178 m. ec. --- Agsume that several branches jein the main duct, as in the adjacent figure, all being on the same floor, the junctions gsensibly being ina horizontal “plane. External temperature -- 20. mw, a } OF the air drawn from the rocome and filling the ducts being at 20. The affective pressure ac- ting uniformly at all the open- ings of the air ducts, is measured by a column of 1.17 m. air at 20, which is the motive pressure. ‘The ducts £ and F are each required to aspirate 25 litres of air per second, C 15 litres, and B 30 litres. Required the sections cf the varicus parts, necessary to realize these con- ditions. | Assume that in the ducts © D, FD, the velocity is | mj; an arbitrary value, in the present case assumed to ce eae fy cert- ain needs, to assure a certain draught, or for other reasons. g_and Bi fubeatione: ! ’ ! t F eg e% © hy + i See ae L 4 hike ant tes MATING: AND: VENT [LAT TON, Q5 se Therefore, tne gsection of one of aig ducts.-- .O026b ms., the discharge: being 025 me., and the# side of the square section. .. 168m. The loss of pressure in tie duct from EH to D, for example,” comprises: | 1 tiony hi +-) 8. -- B&O. rsa | 8, AI -- el V7 n¢ he 0. 42 xe a eee ese Se g 0, Ope aletaY. | | OQ. 13 “peek in nlet -- 1370; and at Donly ~- 1. 170 “assume ae velocity to be. ‘ m4, causing no Icss x. from change cf velocity. pee: section hain oe ae the total discharge being.-- .025 +. O26 Ke the: duct -- .2£4 m The loss of pressure is shat tons el pole | eee ae HX . "Ho =< -- : 0. 068. “enters at Oi bringing Ie Nigga of air. Preasure : ‘1.1%, a8 for the others. It then becomes. ne- y Bet Baieeer that potnt and C, the loss of pressure _.205, making the pressure at Ds <4 > O68, v Trial. --- Assuming velocity in branch C tc be 1 m., tion is 2018 M8., and side 2123 m ‘The loss of pres- ecnprises: As mee lO. i Bhar hy Fak (la < 0.180 Viera i Os 123 » eg angle bend. ae oe ap Ba sat | 0.023 Omisscon hee. See. bAteine “Bog g The slight logs from change eefoed Velocity at C is very small, | making the tetal loss sensibly -- .156, which is too small. The follewing ‘mean values will then be adepted: secticn -- . O16 m8&.; side -- .]27 mj; velocity -- .*3 mj; pressure at C “then. -- 965 m | | “hs sume. Im as the atenits from © to B, as in the preceding ‘portion of min duct. The secticn is then . O65 ms., and the Giseharse =- .065 mec.; its side -- .285 m The loss of pres- sure igs: then: Fricvton, L --. ABBOT AL Re i gt ate ‘3 , OBT. a - 256 2g | Pressure at B =- .9865 — .057 -- .908. The pressure at the “head of the branch B -- 1.17 m and should fall to .908 m at B, making a loss of .262m. Preceed as before. Frreat Trial. --- Assuming a velocity of I m. in the branch, the loss cf pressure wil! be: p *t 5 ‘ J, 7 i orads A “a ¥ r : ee oC oh LS SRE CRY RR. ERY HEATING AND Yer HLATtOR. f 66 lO. =< Me th Pk Pe «We ahh ie mie t Perl 3B. iny 0.42 X I*-- 0. O02 % ieee PA g é 20163, oat ‘is too small, that it becomes duce the secticn and evesie the velocity. | iene 1. 20 ee then: 2 ry oy) Ae 0.42 bea 20° bn 5/0, 03) 1141.20 a la iO. O10 te exist ae B, if the velocity of. ‘batio Of: Roehl one -= patio of yve- SES, Table 26 gives .14 as the i re instead of .262, so that the velocity.is 2 too great. The difference being small, we can aBpsume wing values; section ,O20 mM. 8.; Bide. 161 m.; veloci- pressure at Bo .908; volume of discharge .095 mc. Ges scharges of. aa) the branches. roduee a veloct{ty of 1 m. beyond B, the pressure at F, he less. he liste Band F, must correspond toR a veloci , and - . O51 m. re reduce the pressure from .908 to .OB] m., the loss ci Pee ren B and ¥ must, bse .857 5m With a velocity cf cae Ee ee: eee O. 270 ee Ve, 308 22 Oak x. 1s 5+ es 0. 917 in a8 Y only. 297 m , because the velocity of 1 m. is too Assume this oloeyey we be 1. , Making the section . 0635 a and its side .252 m. ag Noeles are then: | eduction of secticn. s--1.0--0.67.. O.11 4 1. 50° --. 0. O13 ee Mee : B18 ae ite AAT: PA ae C96 pee 146, G80 X 1.50. == 0, 75£ a 0.262 — Ve ig g, "Right angle bend, es Oe bs 50* : ee QO. 040 The velocity being 1m aa far as B, it should then becone 15 om according to our aessumpticns, producing the effect of a an abrupt ré@duction of section, having the ratio of the vsle- elties: -67. Under these conditions, » ame eve ne & f- 2 @ AE : oy DST es a “ot : fe Wath, £5 ae iy tet 5 | REAT ING AND VENTILATION, C7 ficient of .the loss of pressure is about .11. Total loss -- -at2m , instead of .f57, ee that a velocity of 1.5 m ia a Little too great. | ; Assuming the velocity -- 1.45 m, the section fer duct from B tc A, and that of the chimney flue should -- .O€65 ma., ites side being .206 m The sections should evidently differ for the duct B A and the chimney flue. Fer example, to make the velocity -- Im between B and A, requiring a section of .O88 enone deducting Losses of pressure frem the motive pressure at Abo determine the section from A to C, by means of the con- dition that the loss from A to C should bring this pressure to that. corresponding to the assumed velocity of discharge betw- een A and ©, would be a repetition of the preceding calcula- tions. in a slightly different form. ‘inally, ‘the ducts =D and F C are found to require sections se m2. 8.5 CG, -Ol6-ms.; B, .026 me.+ the main duct. from 0 - O50 me et, and for the porticn BAC, .O68FE m.’s. Brialiery, ‘the sections would have been very differently ar- iged for a velocity other than 1m, oth in the ducts & F, the different portions cf the main duct. These elements can be variec at will, furnishing as many different solutions. “PRACTICAL RESULTS. “Underlying this infinite varisty of solutions is a permanent fact, which 1t.is well to note. [n the case of hot air ducts previously condidered, we obser ved. that the motive pressures at the entrance of each diag from. the main duet, diminished along the main duct. [n cass of aspiration now considered, the motive pressure at the ir ets ‘of all branches are equal, at least if the branches are abl: located on the same floor, but it 16 necessary that the pressure should be reduced at each junction wihk the matin duct, to become equal to that in the duct This last diminishes as {t approaches the aspirating flue; evidently, the loss of pres sure must be greater, the nearer the junctions to this flue. ‘The loss of pressure in the duct B should be greater than in G; with equal sections and lengths, it-is necessary that the velocity and consequently the) discharge in B must be greate than tn Cc. The contrary is true when the branches are fed from the main duct, instead cf the reverse. With é@qual sections, a greater length of B or more numerous bends, etc., are required to eatablish the equalities of dis- charges and velocities, the loss of pressure in B being in- creased. With B and C of different lengths, B should have a attaller sechion than C to produce equal So aa alae Mia We will next examine the case of two main ducts or different flues, joining a common aspirating flue. HEATING AND VENTILATION, , 68. The a catine observations are applicable to each of the Matin ducts and its. branches. Then, as stated in case of aspi- Pating flues from several stories, the motive pressures is ongest for that r su wr ats) mu. % at * 5 & Be ‘ cr & a weakest? for the draught in the Bypar story, st in the lower story. At the junction, the pre 38 wual: therafore, the loss of pressure must be duct. from the lower story. With nearly equivalent sections and velocities, the velocity ty debe a4hen be greater in the lower story, and the discharge . A greater length, number of bends, changes of section, , rhe: Toren me will entirely of partially compen- reat 6s in tas Cnae the Ste ttse ent : | ‘are ay caaareed in practice hen being. regulated by valves or apedtal oA np ofa duct is to be eens ab oy a | by the redia penin le 2 similar aicabeect Ogee at the middle or ‘ let of ie duct: on, the reduced escticn may be sorneaved | with the inlet or outlet of the duct by means of a nical portion. ‘Wea will tnvestigate the conditions of di aer. the different eonditions with equa! pressured. hee ga. the adjacent arrangement, the coefficients of res Pei edns eon at inlet. Pe a oerietion, Lb -- 30° --) 75, d QO, -4 ‘Letz,ing v -- velocity cf discharge at : this part the velocity then -- v x .01lAS ‘alying’ y by the ratio of the sections. Loss of then 3, 46 Abrupt reduction at outlet, ratio 1-~ .063. et Taeresistancsa -- LA owt ie Mowak’ = ASceume the pr igure at the inlet -- .06 m of m cf a column of air. This pressure must equal juss found — pee Pies ~* baat 3! Pes . om ‘4 47 mc. -- volume cf digehares. econd amrangenent, we find in ths eane- way, Reduction, at inlet. Mrie tion. as vetesl em. same. as berors at ou Abrupt reduction at diaphragm. D = Abrupt eAlargement beyond do. =Vi2s 8 kK 43.18 +- 1,60 m =~ velocity at outlet A Ms Kea at i yoi=m- 1,80 X% 26 -- 26.665 %-~ velocity at diavhragm, the sect ton of the pive is 16 times that of the hole in vhPasm, The result is therefore the same, wherever the diaphragn be) placed in the pipe. £-5- 30, wee = | lf it be placed at the inlet, we fi (pg redaction at inlet. pitting f = Abrupt enlargement. Hy hee Ce OE 4 Lig * js Fs in reference to outlet vel locity, is . ° “ 347%. BY wwe ge, Reap 0 NTA OX|E «= velocity at inlet. By comparison, . ohaitibne of discharge are avident fame, even with a xzreat reduction, the differances of Being very ‘slight, and perhaps resulting from uncertainty tO the @xact values of the coeffictents D and F. Hence, diapnragm will produce equal reduction cf veiocity, placed any Dart of the pipe whatever. Tf the @iaphragm be omitted, the pips being freely open end to end, the sole resistances are: Reduction at inlet. Preietion. : Or 3 . . caine SD cro3 Ri. ¢: 2 Let the Peaheee Grytine be connected conical or pyramidal vortion. Proceeding as before: St tr wile Mc Pe. BN Fd eM Be -S HREATING AND VENT I LAT TON. . 70 ey a Reduction at inlet. : Dw OAS Wednict ion. RAL aia t ~ “> fr EY aed dienihaa ! a B85 te, 4 ef Ese Rye! i ree. 7 TE pietes) as in the first case. . OTF ZE V p22 UPAGUal wedumiion, ratio. 063. D --). 27, sf i Loge '-- « BT OOOV ee 2g _ piensa _ehbn8 Vie Le es AGI =- 26.67 m °-- vyelecity at outlet.22% Vig. beBs RE, Ge cP seo mis-~ velocity in pipe. ee Tf the bdueed orifice be placed at the inlet, _. wa find: RNeductiona at inlet ND -~ O. A’ (Gradua! sniarg erent, ratio .O83. E-- 0. 86 Be j ay eR : irs Loss in that part 7; P30 4. 2ch8,' 332, BO vse 2g FPLiCtvi0On in’ pipe... F.4- 3.:40.. Logs. 3. 40 vie 2 g x a6. 16 at outlet.2Z ae ; ne OF an 20 y ee locity is nearly the same as in the preceding case. The meifect is senstoly the same.with the contraction at t inlet or outlet, Mee de oe Ah 1G. =~ 26,40 -- velocity at inlet. Mite oe lGek 1.66 «© 2264 m.c. -- discharge. eae diaphragms, we found @ discharge o1 . 247 es a little le than with a gradual reduction, as might be expected. co EME is bonaid berable in beth cases, as he O discharges 2.203 m.c. . The etfeet of a contraction ig to reduce the neral disc. args; the velocity in the pipe is alse reduced, frem 13.77 nie TOr-an open pipe to: 1,65 5a) with a gradual contraction, ang 1.58 m4) with a diaphragm. But the velécity at the orifices is considerably increased, LrGmes.77 TM. inithe open pipe, to 24.73 m. in oneiwith.a dia- Pategm, and to 26.40, with a gradual contracticn. TAS peo eine the use of caps on chimnéys for increasing the elocity of discharge of smoke into the air, where it is expe- 6d tG the contrary action of the wind. This consequently di- 3 whe cae miewe Von pipe ad oY 3 > % 4, ninisnes the draught from the fire-place, tf too great a quan- tity of ecld air would coc] the flue tee much. On the contra- mY, this result might be injurious, if the ae ape did not nave draught sufficient to cause proper combustion. LAT iNt AN) Ven? LLATTON. | } CENSRAL CONSIDERATION OF CHIMNEYS. DRAUGHT OF CHIMNEYS., bo CRHRORST ICAL FORMULAE. : .~ Simple en dmibey Flues, --- When a chimney flue is filled with air of density and weight less than those of the external air, the weights cf the air exerting pressure on beth sides of the lower crifice become uhequal, ibe talta deb is destroyed, and. motion reaulteas 4 © Bet’ pie total height cf chimney flue,.as..in he fig sures, Let a: - density, and © temperature of external air. i Let ee dansity,” and t ++ tenpsrature of air in flue. en, Eide oi atmospheric pressure at the top of the flue. me _ Aft. the bottom of the flue A, the external pres- Bure: P is increased by the wataht of a column cof - external air cof the height I. The total external pressure then -- P +d. The internal pressure at A equals P increased by the weight cf a column cf Warm air of hetght HE, making a total internal pre sure of P + Hd’. Thy motive pressure is the dif- ference of these pressures, -- H(d - ad’). Since qd <- de F and ad’. .-- de ; letting Go == 1 + ad New at lensity at temperature O, the motive a wilt “be: Wed =.Q)) = Hdef me De Ne a(t - 9) y y 1 Pad 1 + at + aQ}(1 + at) This pressures ts here expressed in ight: to express it in ine Asieght P of a colunn,cf warm air it is sufficient hguate the weight of a column Prof air ¢ t and density a tc he preceding ie % a “es Had act SB ae (l + a9) 1 + at) “Substituting for d its value do Tat ate the temperature of the external air be oe > Pe Sed I+----- = ' 1 { q-- + = --- $ ecordance with the peat bon of | vos -\2gP ~=|(2gtia(t = 8) 1+ 26 The velocity of cold air at @termined by the fact that the me densities, consequently: velocity of the col i With the external air at thes@ formilas become: Vo =5 5 268 VH t , and vi -- vee (1 bat}. We Nave just determined the motive preasure P is interesting to examine the variations of a) & ae * HSATING AND VENTILATION, aos upwards in the ren Let M be any point in the height ef the flue, distant h be- low the top of the chimney; evidently, the upward pressure Mi.~- the pressure at A — the weight of the column of warm,air between. M and B, -- P+Hd— @'(H — h). . The downward pr@- ‘cure -= pres Sive at -C + weight of the eclumn h of warm air, * cee P+4H a', The motive pressure then -- H(d. - d'), and is there fore manchanged threughcout the height cf the flue. a patp is slightly compressed, of its pedicns increas ed . the bottom of the flue, more than. elsewhere, but vue is 50 smal q. that it. may be neglected in practical cage aes in Form cf a Syphon. --- Let the ‘Tlue pari & Syphon, as a “Bote. phnd pate furnaces, § Stoves, cr aspirating chimneys. | : Draw the Kost adnte | fine A Bas in ure. At A, the weight of the air -- it -- p + Hd’ at B, employing the for wren. Tne did ference .- Hla -)d’) as and the velocity ef flew of the air wil! | Yo-- ,208|/H(t 1+ a8 The conditions of flow are, in general affected by the difference of height of | inlet and cutler crifices, whatever form of. the flue, or the number cf bends in it. ry the flue were oblique instead of ver tical, the. same be true, as the vertical distance between the inle t and always Deternines the motive pressure and the velocity c .. S¥phons with Several Temperatures. --- These conelusions require mediffteation, when the temperature of the air ifs nee S, threnghcut the flues. Lett? - temperature fron the. 6. prom) to Ci da’ and d* being the corresponding The pressure at'D acting from t to right, -- the pressure from right’ te ph Ns the excess cf pressure -- Hida - oe ee Lae ‘a ere ee ge ! ‘i Gh wae y + ad 1+tat 1 + at? lar The eelumn P of gas at t*, equivalent te ; Po -- a(li(t'— 6)(1) + at’) #hettt )¢ i (l a8) t!] + at?) Here 9 -- external temperature, as be becomes ; Pte taphet Fr hep!) 1} L + ar? ANG YP t* -- t' ;'P -- Hat, as in the first case. If t', the temperature in the first part of the flue, be less than t*, the tenperature in the chimney, the height P producing the draught, is greater than if the flue were net Syphon, anc if the duct A were horizontal, directiv joining 5 L no “HEATING AND: VENTILAT TOM, the chinney ar B. The syphon AD 8 thus augments the Tris: case oceurs in some apntrauing chimneys, when-a heat arate is placed at B. (or D/). DPiminution of Draught tn Avvaratus with Descencing Of the contrary, if the air were warmer inthe firet Ot the duet, "whan in the chimney, the draught would de ee or it might entirely cease in certain cases. oe Tet the haat th temperature -- OQ. Then tf t? ert : = huee ok he Oe Finan tee | te at! | Irepeet ten of this formula. Abie that P, the height of dem ‘aup At ta less. than if the duct A directly joined the flue t. Sy the gemperature in the chimney being 1’. th qe et a 3005 and t* -- 100. ‘The draught wil! cease Udo sk and h b4 such, that 100 H -- h(300_ - 100) # £1 -- CADE hy: ‘or h -- 1.05 rH. 2/0 Ro as the height of the gyphon. were, put, little more a: um that of the chimney proper, the draught would then entirely cease Tate arrangement may evidently produce great rea jueticn of bhe ‘draught; so that it is necessary to consider this anc ecmpeéen - gate for {t’ by a greater height of “the chimney. fe le heat ing apparatus with descending tubes, ths air is “hewter near the grate, than when it reaches the chimney, eoming in contact with the cold air, which is to ve warmed; precautions must be taken accordingly. The less cf draught | inereased by the greater length of pipes and -number of, bends, feaulting from the changes in direction of the pipes, which “inerease the frietien and the various losses cf pressure. ' Completes Formula. Actual Velocities. --- In treating the “flew of air in ducts, we have in a general way shown that the ‘actual velocity v of flow is easily expressed by means of the | motive pressure P, and as a function cf R, the sum of all the resistances due. to friction, bends, and changes of section the expression obtained is;* vy -- . ; , letting rs Vora the theoretical velocity V2 g PF. ‘Tt has already been shown how ORE obtain the all cases; also, how to determine P for ordinary in case of an erdinary chimney flue, .P then be’ -- ¥ --|/2gHa(t -_9 =~ : ? VTi FR)(1 + ad) If the external temperature -- 0 2g Hat -- . 268 i-+-R As befers stated, the velecity ee on Soe A Tei pete a, ay he ~~ HEAT ING NO. ike NT TLAT ION, RSs JG + a8}, 07 P&S = ° Mts | ] Bo at we alt ae mba. formula ig based on the assumption that the areas ‘the inlet and cutlet orifices are equal. {f they differ, “velocity y'. should be multtplied by the ratio of the arsa 40 that of; the inlet orifice. found in the manner here indicated, whatevér -ehimney | flue; the regietance R is obtained cating the flow in ducta: v is then found by lues on. ada Pipe kot vo--|\/e2 2 FP. oe : 1+R st wo WLit resume Zxample |}, computing the resistance cf duct; being ai chimney flue in. the “Censervateire des Arte et des Metiers. This chimney has a cap, Hi. Mn pera and ,araught height ts. abeut 20. 6 Assuming to-- 100 ture of the smoke, and - temperature of ths es term li t then -- 50 g Pound -- .7864, 86 that (page SY). vay Wise ot ia >. 30% 4 / A dibe eae . Prox terete tined até 8K t : yo ge RN aN: i x ; me DRT aula i gah Bye yf yeas Ps IS t 8 “8 4000 4 - o- -X- 5 x 4O 2 smoke oints ae the flue, aN dneiiema is cate e relocity phe. ra- the K-> Leo-- -f the point ‘Thus, from g to ; ¢ 17 Ss ~ he > == AlO~~ ~o = en o Kos 602=-% 1$o- ~ _ HAL @, the velocity -- 8.1% %.038 #.150 -- 2.07 ‘Axample 2. Chitaney Flue. --- Omitting the cap, game chitaney, Rwss found, -- 3. 374, and ie then Replacing the cap by a cylindrical | nei? height nor temperature {s changed. Vises §268)/ 2060 (-- 5: 80 1m. 4. 374 stead of 6. 17>m., found. tf first case eae g to hy tae veloet - §.20 nm. ihstead of 3. 57 firming the Statenent as to the effect .cf the cad; 7 t us digo hars, ; S. ¢ HREAT ING AND: VEN’ ty of discharge being ite peaged in the ‘flue itselg. From b ta ¢, the velocity -- The veic ocity of aoces oP ane 4. BO 4 1,30 -- 4g" TM. ,8if the section at b remains the same as at the. outher)” But’ Pale: ion at the outlet being . O06 mss, and at the antet Oey Sat Ae AS A O38 1, O07 mo =<) Veleoaiy GF ol @.a i she inlet b. Bxample: 3. ot -Adrp Furnc eaei+ We wild Pes uae. the example Vs Ss already studted on vage s¥ eight of ete flue 1 Pia but the Being height . yoint, abilesa! the a Oas Oeeore. fea by ite 2 passage through the fuel; assume that = hetght te be 1B, BO Me benperature {8 the smoke: -- 109; of the externa! Pile LO, : The verm yee. oO) then 4 1B | lL -¥F Ae ae OL SACS 3 3 We find the loss seg ie vin 3 ra oa Then Be i, VaR ee 276. The velocity of aise charge of the smoke o Belem. 2 Rxamole AP Pop-Air Duct. --- Rasume the ELEY | ae: a her ee duet with BNC A 3 4 > fureations, already Scuninen on pag SZ. The commencement AB of SONXN™ F duct is supolied with air, hea @ a furnace N to 50? The temp of the apartments, into which branches discharge is assumed 15° The section of m9 at ibet tf .30 A .30'", , the same’as that the duct A B; required py least height, which may be-assizned to vertteal duct. f {t has been shown, that under given conditions, for each cutzlet t discharge its required volume of air, the motive pressure at ‘the beginning A of the distributing duct miat.-- . Je m°, me ured oy the height of a column cf hot air. The velceity in the vertical duct will be the duct AB. First assume the required height The loss of vregsure is then: oe ae ee Ss 1S oy Stare neg eae meee, — tein 2 ioe se at. the left, the weight of the air -- dfjH - h) + h dott (1 bat), H - “h being the pressure at the top cf the / chimney, and h dw (lat) -- density of the air forming the column h, t being temperature in flus, and d, -- dennity of the external air, assumed to be at 0? . ‘The pressure at the left, expressed in a column of air at t, we d(H = ee he (1 a Ne or -- H(l + at) —-hat. The. dir- Ln aes T+ ate peste or Motives pressure --- me, ats obtain vt ee ie a heiehesy er ite 4¢ warm air. ) And wv" -- v! 4) Fat) -- velocity of entrance of the cold air into the flue. _ After the regime is established, the quantity of s61a air vaseing through the crevices equals that abe gute by the flue The sections of the resepetive apertures being 720 and . O44 2 8. , we have: a eee se ae 0484 \\2e] (H'— Hey(] tat) tha aie is 1. 45 + oO nN. Tt caare. were no depressicn in the room, the et trs nressure for detérmining the velocity of the warm air would have been hat, under the assumed conditions. On account of the depres sion, this motive pressure only'-- ha t—(H — H'j)(1 +4 at); the preceding equation permits the determination of whe less of pressure (H~— H!)(1 + at), when the temperature t of the smoke, anc. the height h of the chimney flue are given. ‘Perferming the computations, the following reeults ly obtained. W336. 00 me 45-60. (h-B’ )() at)-<-. 24, hat 17098, rat. 29 be ae t-- 100°- uP Oa ee eee Oa B10 i-* 20.80 mi. t--+ BO, ea AR he) Bs BGO 12 Bs tegen Ge <= 100) i. aoe PSS. Oe Ee SAR “emiaently, the: loss of metive pressure resulting from ad S10n is greater, the lower the temperature of the smoke, the less the height of the chimney. In the case ef the loss ct pressure, the motive pressure is reduced to .f9 eent cf its value, if no depression existed, anc to .78 pe: Cent in the greatest. The corresponding velocities wil} e..88 and .94 per cent cf their valuss, with no depression. The CONBSIVUGN@ SBR Cannot be neglected with impunity, and they must be considered in calculations relating to the Graught of chimney flues, or there is a liability to serioue errors, : ite . M h 1 be ve HEATING AND. VENTILATION, uentes of a Renewal of Air through _ C 8% width of the crévicea has been assumed at 3mm, but tf woodwork is very carefully fitted, and the room ig carpe étc., the resistance to the admission of air may be mu ter than here assumed, thus gaatly inereashy the fia pres: and also diminishing the draught. > The natural tendency is to make these crevices for the mission of cold air as small as pessible, since the air with great velocity, producing disageeeadle sensations the chimney draws air from the lower part of the room external pressure is greater at the level ef the floor, at the ceiling, the cold air enters through the lower porti of the crevices. Hence, the warm air tends to rise on account of its lesse density, and stagnates in the upper portion of the room; the renewal of the air almost entirely taking KK place in the low er portion. The heads of the occupants are constantly in the layers of warm air, while their feet are in the coldest, which ig also in constant motton. These hygienic conditions are certainly as bad as possible. Inléts for Air. --- Means have therefore been sought for providing an inlet for the entrance of the cold dir, to re- place that removed »y the chimney. The best and simplest mode is to make an opening in the outer walls, this being covered by a grating, the atr then passing to the heating apparatus through a duct, arranged beneath the fleor. In case cf a ‘hot- air stove, the air enters the space between ita easing and fire- -peot, is heated, and then passes out into the room through openings in the upper part.of the stove. A similar case occurs in certain S¥uxasz fire-places, in whih which the air is warmed in special tubes, which are connected with the duct from the inlet fer the air. In case ef fire-places without special appgratus for warming the air, the introduction of cold air is a delicate problem. We will here merely say, that above all, care must be taken that the cold air does not produce the same inconveniences, as when it enters through the crevices of the doors and windows: it must be directed towards the fire as far as posaible, and hot towards the ocecupants of the room, It is necessary to assign to the ducts for the admission of air much larger dimenaions than are usual. These ducts are too frejiently puh in after mw the srection of the building, so that in constructing the flues, sufficient dimensions were not arranged, and their effect is too commonly insignificant. Insuffieiency of Ordinary Inlets for Air. --- Suppose that in the room considered in the last example, everything remains as before, excepting that gx air inlet is arranged, whoss séc- eh ere Ube IO a8 HEATING AND Pat VLAT TON, be 7 section is .20.X >; 80 m=.07%m,5, . The perimeter p -- .60 m+; area 8 5 62 m.sS.; we assume the length of duct to be 4.00 m The term for friction -- .78; te this must be added the loss for econtraetion at the entrance of the duct, considerably inereased by the grating, and also that for bends, ete. The total value will be at least 1.00. Phen. l eR -- 2.75, and /2 g P~¢ 2.75 -- the maximum posst- ble velocity of the air, making P -- difference between exter- nal aif pressure & and that in the room. This difference was revicusly represented by (H— HH!) , and, Mhough slight, eau- sea the inward flow of the air. The volume of aftr introduced -- .02 vy -- .O12 V2 P. The yolume of air admitted through the creviees iy the docrs and windows, as assumed tn the first example, is dus ‘to the game extess of pressure P, and. -- the ssgetion .O72 miltiplied by the velocity obtained, --|[2 g P-€- 2.87, 30 that this value -- .044\/2 2 P. Hence, under the assumed conditions, only about one-fourth the total volume of air enters through the inlet, three times as much still passing through the crevices. PRACTICAL RESULTS. Advantages of Inilets for Air. --- The ineonventences just noticed are very Bure rent, in the case cf open fire-places for warming apartments. Hot-air stoves produce a much weaker inflow of air than fire places; besides, the air reaches the fire-pot, is warmed, cau- sing a special draught, whose effect, joined to that cf the internal depression, causes the air to flow into the room. The same is true of hot-air furnaces, which are usually pla- céd in a lower story. Hence, it is easy to arrange intets of dimensions suited to the different kinds cf apparatus. With fire-places the case is quite otherwise. The preceding caleulations indicate the necessity cf using inlets of dimen- sions much greater than those ordinartly employed. Thsse op- enings should be the greater, the more carefully the woodwork is fitted, and the better the room is supplied with hangi nge and carpets. Otherwise, the draught of the flue may bet very bad. The use of special apparatus for warming the air has, des its special advantages, that of producing a specia) in the air inlet, as in the ease of air stoves. Hence, : course should be. made to something of this kind in earefully planned arrangements. If the floors do not admit of a duct.of sufficient *pise, several may be employed. -These ducts should be as short possible, as large as eonventent, of nearly square sectt so as to reduce resistances to flow. - HEATING AND VENTILATION, ©. 2 = eee aoe: 3 Ste The’ termination of large inlet ducts near ‘the fire, Lae the admission of air through crevices, with its pesulting ins: jurtous consequences, improyes the draught, and diminishes the | : t in 1 i air, which is almost immédiately remc- oplies the air directly to the fire-place, al! the flue traverses the room; the fire must i » heat suffictent to warm that air and @ temperature required in the room; it efore it is withdrawn by the flue. The ihe to cocl, or a considerable quantity Tig tile talete to the fire, no heat is sorte ued ¢ ae ch is lost when the air is removed. The radiant employed. for warming the smaller quantity of air, omes through the crevices, remains Icnger in the room , mite a eam er this neat to the walls, which are The same quantity of ; shen serves to warm a much larger. room, under conditicns per ‘eats ie 4 Se , a At be we ee ee weet ee, fog HEATING. AND VENTILATION, | - 86 PLUNGING WINDS AND DESCENDING CURRENTS. | EFYECT OF PLUNCING WINDS. oa Direction and Inclination of the Wind. --- We. have previous ly stated that only the vertical component of the wind affects the draught of chimneys. _ The veloctttes and corresponding pressures of the wind have ey Toeagured, the results being given in the following tab! a ae Vel. per sec. Pres,. per.m. 5s. arcelyssencibie. «1, 00 m. Ma 0. 14°KI TO: » b HO At Be OO i to) DO, Sawer 4.00— a 3 br as ee Es : | | : cds 87) SOB, 87 My v 0. 3,8 a 13.54 to 19.80 ‘trong. wind. | 5 BO. - 30.47 to BA, i. Storm. ee EN aa : peiyes re to 122.0 ‘urn teane.. | sag ge ie “To. to G0 A wind: having a velocity of 20, to. 26 m ig hp commen in spring and autumn. The inclinaticn of the wind igs quite vari- able, dut an inclination of 10 to 15 with a horizontal is ver frequent, this being the angle of inclination cf the axles of ae mills. . Assuming a velocity of 1& m and anNinclination of 10 as a mean | for the wind, we shall be well within the extreme cases which may occur. The vertical component cf the velecity -- 2.60 m. and cor- | Pesponds to a pressure of 1.10 kilos per ms. The velocity c 15 m with an inclinaticn of 10 may be considered ag being e- “quivalent to a smaller velocity and. greater inclination, or toa much greater velocity and smaller inclination. _ Modified Formula for Draught. --- Let P -- atmosvheric ». pressure at the top of the chimney, expressed in ki ‘ce Let h -- height of chimney flue. At the entrance “of the flue, ths pressure cn one side -- P +h de + 1.10; on the 4 i apd my mee Dae 80 1+ at 1+ae letting t -- temperature of the smoke; @ -- that of the external air; d, -- density of tna’s ir at 0, -- 1.3, since it weights 1.3 kilos per mec. The motive pressure -- h d, ae ry ae 1 + at The height of a column of warm air, whose weight equals that quantity, would be -- h a(t - 9) » 1.10 (1 *# at). l+a hic nf The velocity of acces of the aie air being’-- v(1 4.a9) , 1+ ty the velocity of the warm air -- Ory 0-0 + ~~_33 —hatt——9}_-_. 541 1 aty nas +497 ‘ be ey 5 fo ¥ ee ire HEATING AND VENTILATION. 22 [5 a(t — 9 Be ee a f 1 + aQ ) 1+ R | Or, if @ -- 0, as frequently happens, v’ -- v + (1+ at). Application to Example. Importance of this Reduction. --- If no account be taken cf the pressure of the plunging wind at the tov of the flue, the motive pressure would have been 2 Ract—- 6) . By the action of the plunging wind, this .( i+ aG@}(1 +R) - C6(1 + at) is diminished sy the quantity lide Riis The importance of this reduction can easily be appreciater. Thus, let © -- 0; t -- 100; h.-- 10 m ‘The motive pressures in the two cases aré peepertional to the two yuantities 10 X - 00367 X 100'-~ 3.87, and 3.67 — .£5 4 1.387 -- 2.51, whatever ay be the resistances represented by R. Henee, the counter pressure of the plunging wind reduces the metive pressure by nearly one-third, The velecities will be reduced in the ratic 1.82 $ 1.88,. and the discharge in the same propertton. Had the temperature of the smoke been 50 tnstead of 100, the notive pressures would have been as 1.83 : .83, being reduced hore than one-half; velocities and discharges aa 1.35 : .91. With a chimney only @ m. high, the smoke betng at 100; the notivs pressures would be as 2.20: 1.04, a peduction of more than one-half. Velocities and discharges as 1.49 ; 1.02. Evidently, a very considerably reduction of draught results from plunging winds, which increases in proporticn as the height cf the chimney or the temperature of the smcke is dim- inished. DESCERDING CURRENTS OF COLD AIR, Conditions for Establishment. --- Descending currents cf cld air are among.the more frequent calises. of emcky chimneys, because they coel the smcké, reduce the draught; and carry the smoke back into the rooms. : , Suppose a plunging wind Go act under the average conditicns previously assumed. From the effect of this wind arfa the de- pression in the room, the air tends te enter through the chin- ‘ey flue. The depression depends on the facility with Which the air is admittfed directly through crevices around doors and windows, étc.” We will assume; in this respect, the aver- 2B e conditions previously wsmmkanwe. adopted. | During the descent of the cold air, it only accupies a por. tion of the section of the flue by itself, the warm air con- tinuing to ascend in the remainder. The two currents move side by side, but in opyvosite directicns. To prevent the des- cending current, its friction against the walls and the suri- ace of the ascending current must neutralize the motive for Which causes it to descend. The motive pressure ha t of the ascending eurrer oy HEATING AND VENTULATION. 68 air is frequently reduced more than 20 per cent by the depression, as we have already seen. Therefore, we will only assume .€0 hat as the motive. »vresaure The counter pressure of the plunging wind inal ~-- .65(1 * at) as al- ready found: which should be subtracted from the preceding value. The ascending motive pressure will then be -- P -- .&0hat —. 65(1+at h being the height of the flue, and t the ten- Pree a 3) perature of the smoke. 4 “The atmospheric pressure at the top of the flue .-- EH = h; the prossurs of the plunging wind -+ 1.10 +#- 1.3 -- .€5, e@x- pressed in a column cf air. Therefore, the total pressure at the top -- H—h+.f5. The corresponding weight -- do (H—~h-+.868), making do -- density cf the air at 0°26! = 0. "At B, the descending pressures is increased by the weight of the i éecendi ng column of air: we will assume its temperature to -- t+ 2, acequired by contact with the walls iden the flue and the smoke. Ite weight -- h Oa ot Z 4 At-B, the internal pressure H’ also iran a certain pres- sure opposed to the descending movement, and which sheuld be deducted from the metive pressure bei ecmputed. The cor- responding weight may be taken -- Hid Then the effe@tive descending LS Bae -- ay + We Saat HW Bb + oh at fheig + at 2() + at) & —————e ’ and expressing it in a column of air cf the temperature t+ ¥, whose weight equals the preceding, we have: 2 H- + .e54 hat (? + at). 7 ath at 2 ee : In fire-place flues t rarely exceeis 100, or is less than oe At these limits, the values of 14 (at + 2) is .86(1 + at.) an -92(1 + at). For convenience, .we will freplace this term by .90(1 + at), cbtaining .©0(H — H' + +.8t)(1 Fat) tha t+ 2 We have taken (H =~ H’ )(1 + at), the downward motive pressure -- .80( h a t; hence, the descending: pressure -- P -- - 72 hat + .785(1 + at) + .50 hat -- .765(1 + at) - .22 hat. Having found the motive pressures, we will next determine the conditions required for the commencement of the downward current, assuming that this current is still maintained in a state of equilibrium by the friecticn of thé ascsnding current. To realize this condition, the resistance caused by the fric- tion of the two currents against each ether must equa! the pressure P', Peri ~% > & : HEATING AND VENT [LAT LON, 89 Let v -- the ascending velocity; R -- the term ccrragponding to the friction of the ascending current, againatéths flue, - neglecting secondary resistances, and we cvtain for that cur- rent; Pov “(1 +R), whenee v> --_P__. A ee Bg g a 1+ Rk ‘Letting R? «- the term for # resistance by friction of the ascending against the cold air. current, we have P! -- R} eexRKXRK, nde eae rade 3 228 xikduBitorduny rvsuivsvir ‘baw RR ' nN ts a results if P. -- 1+R. It now remains to ob- py oP tain the values of R and&.R’. : Evidently, the resitetance to the descent of the cold air becomes less as the surface of contact of the twe currents is diminished. An assumption least favora>dle to the establishment of a downward current is to assume the flue te ‘ be equare. Let .D--- the side of thi square RK flue, d being the width of that pertion occu- 1 pied by the ascending ¢urrent, whose velocity ie iv. R comprises a first term relating to the friction again 18 a surface D and two surfaces d, and -- .045 xX h(2a 4D); to . ! 4 Dd this must be added a term expressing the friction on a surface D bY Contact with the cdld current. Let M -- coefficient for frietiton of air on aftr, and this w term becomes -- M Dh coefficient M is sensibly less than .045, 4Da ( the coefficient of fricticn for rough walls; if .O48 be sub- stituted for M, we increase this resistance, lessen the veic- city, and. favor the establishment of a descending current, giv 4 ing a condition below the true one, and which should ba taken as a minimun. Then R =~. 22 b(D £4) OBE b ( ry: a(D “The term R aa the raktne ance cold current against the ascending curre ~ MxBxdxk M Dh, or -- m UE 1 4D(D - @) Dad The condition then tg: ta 2 P --..80 hat — .85(1+ at) -- 1+R - Dd (D — da) +. § 22(D — d)h PP .7B5(1 + at) —*. 22 hat cae ry yf mDdh Limit of Height. --- This formula shows that if d must -- O, and h -- .85() + at). . -£0 a t i Assume the original temperature of the smoke -- 100, -~ the He eo hee Lae me f friction of the nN wo © vy dh , replacing M by m - d) - 7G HEATING AND VENTILATION. ) $0 quently occurs. By, contact with the'cold air itloses heat, falling te about 70, the cold air rising to 30° or 35° Though this assumption is ob Nedra arbitrary, it cannot vary much from the truth. The temperature t then -- 70, and h becomes -- 5.15 m, so that if the height of the flue did not exceed 6 m, the escap of the smoke might completely cease, under the conditicns of a plunging wind, and the assumed depression.; the eold air can then enter, completely filling the flue. Also, if P’ -- 0, d@ mst -- 0. This merely indicates that at that instant the pressure of the plunging wind will be neu tralized in spite of the depression, bhutvxhaviesverndtagx force efxthexertavair by the ascending force of the cold air, warmed by eontact with the emoke. This cold air. will then ascend with the smoke. Under the assumed conditions, this limit cor- responds to a height of about 17 m,, beyond whic h no descent of cold air is possible. Between these extreme heights, there its a possibility always of the establishment of a‘current of cold air, having a larger or smajler breadth, as determined by the preceding formulae. We therefore conclude from the preceding, that below $2.) the chimney would have no draught under a plunging wind; from 5 t 17 m , it would be sxposed to descending currents and the re- turn of the smoke, always; only beyond 17 m in height, this inconvenience be surely aycided, under the average tions here assumed. Obstacle to the Descending Current. --- From the Jaime formulae, we may conclude that the smller the ratio (1 -R, the more difficult will be the’ establishment of a ding current. Then, to oppose a downward current, it dent that the side D of the flue shculd be made as sma permitted by the requirements of combustion, and that height of the chimney should -be as great as pessibdle. Also, the greater d becomes, the smaller is (14+ R) #R, i.@., & broad descending current is more easily established than a thin one. It is also clear that the larger the coefficient of friction the greater P +P’ becomes; .a stronger upward pressure is re- quired to maintain equilibrium in a very sooty flue. This is ancther reason for keeping chimney flues clean. The preceding formulae also show that the greater the ratic P-+P', the more difficult will be the establishment of a cending current. From this may be deduced the fact, that difficulty increases with the height of the chimney, 4s y found, and likewise with an increase of temperature. therefore advantageous to make the chimney as high as possi! and to have the/temperature as great as possitleé. TA ali HONG HEATING AND VENTILATION. |. 2] “oP. PRACTICAL RESULTS. | , Means to be employed. --- Chimneys of ordinary height anc eonstruction do not usually exceed the required limiting Korg h@ight of 17 m., and are always subject to descending currents | of cold air, being internally in a state of unstable eyuiliv- UB 0. Li Pea rai cc Urabe me acdc | _. The motive pressure, whieh induces a descending current, re / sults from a descending wind and the depressicn within the - Pooms t© be a warmed, this depressicn increasing with the ob -Stacles to the free admission of the air. : _ The first means to which recourse should be had to prevent | the possibility of the return of air through the flue is that Of w reducing the pressure of a plunging wind, and the inter- sak Nal depression, > To diminish the action of the wind, a cap, ventilator cr cowl, its placed on the top of the flue, so as to prevent the pressure of the wind on the outlet orifice, and even comple it to aid the draught. Nata! _ Te diminish the internal depression, the best remedy is to provide farger inlets for air, so constructed as to avoid re- sistances to the air passing threugh them, alse utilizing the special draught within them by heating them _ Other means may be employed; we have seen that the descend - {ng current is established Wtth the greater difficulty, as the surface of contact with the ascending current is increas ed; ‘the ancient, very large , rectangular chimneys should be avoi- aed, since the cold air could occupy one of the angles of the flue, the surface of contact being relatively quite smal}, from the flattened form cf the chimney. These flues should be replaced by ducts of square or circular section, ‘which affcerd a relatively larger surface of contact. At the same time, we have seen the advantage cf reducing the side or diameter of the séetion, so that in practice, ordinary flues are now only .22m. square. This section should not be employed in all cases, but should be varied according to the height of the chimney, and the quantity of fuel to be burned. The temperature of the smoke must also be considered... The auantity of fuel te be burned being determined in accordance with the capacity of the room, to be warmed, the dimensions f the flue should be so arranged, that the efflux of air be Ct’ too great, which would cocl the smoke and increase the prcbability of return of air; still, it should not be too much educed, as this weuld diminish the velocity, and the friction kus to this velocity opposes the descent of a stream of ccld ip. We will further show how to avoid the two equally bad pxtremes; a too great velocity of the smoke, which assures a cod draught, but causes the use of a large quantity of fuel, ith insgufficien ; ie > FOr = ‘oieley Sonar Tt phe ds oe ae ) REAIMING AND. VENTILAT TOR, 2 whet. ineuffietent. warming; & too great Peduction of. the air eyed: by the ‘sts whieh wolela. be econcmical, but would cause sfective di ae “a a “greater WARES of “emissicn into = SR peer Sheatet pega eg ir t,t St ne 8 a WE Draught 2 Amission of Cold an ate of. Ratiee hae on ac- wu tear ont air ABEOU ED eens oie e3r- y t renté the ian: Lead in te ty oF eons on. Line’ contrary, will amy a injurtous.. This is the @istinetion, which | it is imoortant to Whos Bray and. ORO RRT 80 | , iy * PE EATING AND VENTILATION. | $3 ‘yorum OF AIR REQUIRED. = ° Determination of the Volume of Alr. --- We will determine phe quantity of air actually required to pass through the flue, That the.combustion may be properly maintained. pe Tn furnaces of boilers, as well as in the fire-pots of arr and h 2 sis Dagar ad the air aspirated enters the ash-pi of air ig’theoretically required ees of wood, though twice this quan: st Kinde of heat ing apparatus, i.¢., | sie volume for’ coke or coal ts & to nen’ ‘air. ‘peaches the fuel with a veloci- t ‘m™, which is not the case in fire-placeg, 8. ir has a velocity of tm (at most, rand the fire is less strongly, except when the blower is down... | These conditions being less favorable to-the complete com- _ bustion of the air, the volume of air used willy, wer exceed € a) a mec. for wood and 16 mc. for coal. “Mest of the air also passes directly into the flue of the “fire-place, Without coming itnto contact with the fuel at all, thus producing excellent ventilation, but making the fire- Fee difficult to mess and not an ceononical producer of heat. ka Only about one-tenth of the total volume of Be removed is real ly utilized by a fire of coke or coal, still less in case NOt, wood, for the following reasons. The air must pass horiz- ontally to reach the fuel; the passage beneath and through the | grate and fuel is obstruct ed by the greater friction, so the cr merely passes ‘over the surface of the fuel, rarely passing _threugh ft, and as soon as it becomes heated, the air tends te rise from the fuel and pass into the flue. ‘Therefore, we assume 160 mec. to be required for each kilo of coal or coke, or 100 me. per kilo of wood, as a minimum for ensuring preper combustion. _ For ventilation, large fire-places with large openings and a relatively small quantity of fuel, are preferable, For Warming, the fire-places should be ‘ow and narrow, and the relative quantity of fuel should be graater. ae ae Tene eetmemneent ey Pes lnes soe re gee SR Tiag hey her vrs, 3 re AT TON, ‘6 of the smoke depends on the volume of air quantity of heat supplied to this air by the tn, The air removed by the chimney comprises; | , it, A certain volume actually required for ‘combusticn, alone taking art in the oxidation of the fuel, being about 3.3 Bo 3.5 mc. per kilo of wood: according to explanations on pageg /4,/%,and Table 2, the corresponding quantity of smoke requires ‘1.73 calories per degree of slevaticn of it temperature: if Poh the primitive wesparature of air Mec eet BES" the - OR@om, ot -> temperature of the smoke, then le 3Cbi <7) = quan- tity of heat avsorbed byphite- first portion @f the air. 2. A much larger volume of air, removed by the draught, but net taking part in the combustion, n times as much as the fer- (mer, -- 3.3 nn. For each degree of elevation of the temperature | 3-3 mc. of air requires . 95 calor{e, as an average; the total quantity aosoroed is then x€xxxgk . 95 n(t —7). .— Then (t -7)().73 & .86 n) -- total quantity of heat absor- bed by the smoke of 1 kilo of wood, and supplied by that weed. I Kile will supply 2600 to 4000 calories, according to xke {ts nature and dryness; we will assume 3300 as a mean. Hente, t - 7. a C's (2) We | 26 n+ 1.73 By #quating the heat furnished by the fuel, to that abscrbed by the smoke, | The quantities of cold air entering the flue, and ef warm air leaving it, are equal. The volume of the cold air -- 3.3(n + 1)k, Tetting k -- number of kilos of wood burned ver hour. } ! Let v -- velocity of discharge at outlet orifice; s -- sec- tional aréa of the flue; the volumg discharged per second is 8 ¥; per hous, 3600 gs ¥, which is at the temperature t.. Its volume reduced to 0° is 38600 g v+(l-at). These two vol- -umes being equal, we have : 3.3(n + 1)k °-- 3800 a v (bd). 1 + at) oer HRATING NID ) VENTILATION: ~~ ‘ | eee the Smoke, -=-. To complete iia expression of - elation required to “exist. between the quantities just “cons idéred). me 1 Now have to recall the knonn relation existing “between the velocity v, the height h of the flue, the internal & mperatures . and &S, and the wa resistances op- smoke. ~ fistances due to fréetion, to contrac Ss o bends, etc. We: geaume the ehimney to i OMe , phe eee se ‘9 etneala other form of. sect {one p the. erimeter, = sf aes hats (¢). . a ghee 60 + 7045 By + a9) at BIS Ae Ee pe wt i This. express ton. assumes the uence: of fw no pressure of a Plunging wind or’ internal depression. But if the precautions previously indicated have not been adopted, — we should only ‘take .£0 to, .90 of. this velocity. | On account of the large value of n, equations (a) and (b) may. be replaced oe) the chi det auhicns without sensible error. . 7 ie = ¥ oy a t i ag == 3300 (a’ ) me (a 10k vm POO (b)} be Oke | whence, SB Vo 3k Mscoliil oe of ‘the E nanione, \-- Constructing Table 31 to represent the values of , laying off the values of t - @ - om she horizontal, and those of Vt =- 9 on the vertical scale, it is evident, that the curve eank eee ita the last values dif- | fers but little. from a straight line, between the limits of -30°and 100° usual in practice; hence, ‘without great error, we may write: Vt - 0 -- .68(t - 6) + 3.30. Introducing this new expression in saat ton (@) for the ve- locity, this is transformed Ee 2 a y! ye 30 + .069(t - O}))(1 + a0) (1.504. O45 ay (ec) a | Inserting in this equation the value of t just cbtained fron equations (a’) and (b'), taking but 90 per cent cf the veloci- ty, on account of the internal depression, we have: Sv Mei k + s|. 80 +. O166(7 - 0) Rp -- SAME ET Ee aRt AXE | 05(1 + ae) — .0088] R’ , (¢’) my ul me. bie u ot, ha rm 7 A, 4 PRN E Ch se » ie hee wee, i ee ee 3 an ae is AGN ws * RATING AND VENTILATION. et coir. ‘For’ the chimney of the Conservatoire, etc., page y7 , h -- 20 m3 Ss -- .Of70 ms. 0.29 mz k -- 7.88 kilos; ned mata Ry 08. wy I. BO + . O45 X 69. a Vo BS -- 7. 26. ce X 2.08 X. 087 7005 XT. 68 +. 5D fa ith ak -- 8.10 the ae TG ~- 77.6. . _ piston # 62.6 -- “47. 90. -- 1248 me. -- volume of ecld air locity. of 4.59 m., we should find nd pee pape meres cold air ical valves ‘as in Example 1. Knowing Introduce ‘the value of v in eq- that ‘of. h, replace k by its value # 4), and we have: me tet. be s 2. OF [1 + Via -- Nauk conde: mes 34406 m + ea oe found in the first case, and y being given, “ is ea determined 2 0 mint in the manner indicated in Ex. 1. > Gtven, the sect ion 8, doameter d, the requi- loct and the quantity k of fuel; to rind the height rod | te. produce this haben ale Adopt the preceding nu- es oe - O87 rat me : ity ¥, we have; xt vorbis oar tte babe ter ee 005 X 7.88 4.58 xX 15. 09f1 +\/1 Frey. _ Performing the Pale lerag 203 m— 2.06 mes O, and m -- id RE. ° Henee k -- 6X 2.08 X. Oe7 X 7.20 -- 7. SE.) Example 4. --- Given, the height h, the quantity of fuel k, and the Te quired. velocity v; to find. tHe" sect Lon 8, oF the cor responding mean diameter d. The simplest way would be to assume the mean diameter d and ene sect ion oy comput ing the Le ikebigrigh oe yelocity;: to then ApTgRgp wt ytresith tos ous a 2. the velvetty: v of flow can be nae finding the velocity, ‘the tém- be obtained by the equation ; | the volume of air will be | - 3300 -- volume of: wees Me Wie a lao obo 3000 « calories in- Ces as. follows. eg eer (2). 000026 k and g* fe hlequatione ae (2), (3),,° (4) and (5 }, all ques -. Bae fire-places May be solved, under average te Lea tayon! the height ef the flue, its section, ' dleneter 0 ie re the quantity k of fuel to be burned per hour; ‘te find’ the velocity, and the votume of air removed. | HEATING ‘AND VENTILATION. 28 compare this with the required yelocity, obtaining the true es Tution by these approximations. Uf the section be square or circular, the mean diameter -- - its side or diameter; for any other form of section, it -- 4% | ~™ s being the area, and p the perimeter of the section in the values hetetofore given. ies uming a square Section, its side -- .3!1 m Then d -- .3 O861 ms.; h.-- 20 ms; head +- 64.5, ! Then R -- ~ sy» t a S Me 1,50 +4 .045 xX 64.5 = 7.88 2a: 6,412. 6 X 2.13 X .0961 : v -- 008 X 7.88 + .58 X 2.13 (147. 41a) -- 5.08. 1) : ~O981 ~ 3 But v is required tc be 5.10 instead of 5.02; we therefore | Feduce the section, making it .30 m Square, then obtaining the required result, | | _ GRAPEICAL PABLES., Construction of the Tables. --- From the number of varia>]e @lements, the results of the preceding formulae cannot be giv en ina single table; but by means cf the two Tables 32 and 3 al! the relations may be known, which can exist between the four principdd elements; height, section, velccity, and quan- tity of fuel. The horizontal scale of Table 32 gives the mean diameter or side of the section of the flue, the height of the flue baing found on the vertical scale. Each of the given curves corres- ponds to a particular value of R’, which -- 7 LU oli aa | tea Pi, | 1.804 .045 hed In Tasle 33, the horizontal scale gives the number of kilcs ef wood burned per hour per ms. of the sectional area of the flue. The velocities are given on the vertical scale. As be- fore, sach curve corresponds to a particular value of R’. Al! the preceding examples can be solved by using these Tables. Mods cf using the Tables, --- Example !.---Given, the height of the flue, its section, and side or diameter,:.and the quanté ty of fuel burned per hour; to find the velocity. Let h -- 20m; s -- .087 mS.; meand diameter --.29 m. — k -- 7.A8 kilos; 7.88 4.087 -- ©0 kilos of wood per ms. flue. On Table 32, a vertical through .29 m. en the hori zonta! scale , intersects a horizontal through 20 mon the vertical! scale, between the curves for }? -- 2.900 and R’ -- 2.10, quite near the last; hence,.R! -- 2.009, On Table 33, ascend a vertical through $0 kilos to the point where 2’ -- 2.08, taken between curves for 2) -- 2 OO and 2. 19, a horizontal through this point gives the required velocity -- 5.10 m. on the vertical scale. a HEATING AND YENPILATION, ah 99 ae Example Po. - Height 20 m.; velocity &. 10 m3 mean diame- “ter~ - 29° ™M 5 ‘the section being O87 Th, Bax Required the quantity of: fuel to. be ourned per hour to, vreduce the given velocity. stable 32, take 20. m. on the vertical, and .25 m. on the Abe beaten Ge Ro -- os on as ‘before. 103 mm, on Hn rortipa.! the pooh ty ye- Requi- - ini 10. mn, ‘and a verti- ig! ‘their ae 00 and 2. 10. hig 8 elas! het ne 25 m, for exam- -7 0835 me. ‘The quantity of wood per hour - 0625 -- 126° kilos” perms. If. the section wée its area can be deduced from its mean diameter, as in! » On. Table 32, take the height 20 m. phere 225 mz the point of intersection corresp- Ro .-- about 1,98, On Table 33, ascend a vertical throu 12¢ kilos, oa point. corresponding to R’ -- 1,98; taken a} twee curves: for R' -- 2.00 and 2,10. A horizontal through a point: gives 5.70 m. on the vertical scale, which is tco fy large, the given velocity being | but: 6.10 m rence by assuming .35 m. as the mean diameter or side ection, whose area then == 11225 mas., and 7.88 42.1225 -- kilos fuel per ms. of flue. | By Table 32, Ri -- 2.21, & op a height of 20-m. and diameter of .35 m By Table 33, for Ro oe- 2.21 and 84, 3 kilos. of fuel per ms., the velocity is ALTE se a a ee is too. small. The true side must be between ne dae “Assume the side to be .30m Tadle 32 gives R’ -- ‘about Bei as for a height of 20m. and side of .30m The quantity of fuel -- 7.88 4 .09.-- 87.5 kilos per ms. Fer this value ‘and R -- 72. 10, Sable 33 gives nearly the required velocity of 5.10 m. We know the ‘true side to be .29 m. ean estimate the effect s on tha Semon of the fuke flue by ps Influence of Quantity of Fuel. fuel to be successively increased. Since neither the neight nor section changes, fable 32 gives a ecenstant value for Wu - Suppose this to be 2.00, for example. — a de about 4. 27 -m. up to. the Vine for 100 kilos; this corresponds to a velocity ° eG 5. 20 m. “Also, 140 kiles give a velocity of 6.00 m. tt the. em6- fire-place alse increases the velocity of the sme ; i; a fat being known, eh s(n 126 represents. the volume. of cold ai eens, 60 8, 100 s, and 140 8) ‘kilos. -of fuel burned. The , corresponding - total volumes of air are ‘12360. 8, ‘14350 s and : since the. number 0 f:. kilos: of wood is increased. ~ Lr eet. AND VENTILATION. © | 100 PRACT ICAL RESULTS, 2 a, By means of ae Tables ,~ “whose uses have just been explaing as wellas the ‘preceding formulae on which they are based, we each: ‘elemeht just. considered. | es asione the quantity of On Pable— 33). ‘taking 60 kilos cf fuel per Mm. 8.4 ‘the Sotwalies faking 100 kilos cf fuel per ms.; follow the eurve for i pbs ph oe that an ineraase in the quantity of fuel burned By means of formula (2), the. temperatures of the smoke cor- "responding to these three velocities are. easily found to be about aig 84 and 108. Hence, | the temperature. alse increases with the quantity of fuel. ‘purned ° ‘in. the same. fire-place. 4 The; volumes of air removed are easily determined, — . ey By” formula. CL yge find the value of. ni, ‘and the tempera removed per kilo cf fuel. We thusvobtain R06 eek 143 and PG ere. with the velecities 4., aa 6. 20 and: 6. 0 Evt ently, to the increase in fuel corresponds a Pa ainuteen aye the quantitiy of air -pemoved (per kile of wood. oo. his: does not mean that. the: total volume of air is less Phus, letting Bi <7 sectional area of flue, we have in this 18430 Bon ta Vie. “The volume Ae ead. ain | pedov ae evidently. inereases with the aahuare of fuel Durned,. though not. in the same ratio, the quantity of . fuel varying in the. ratio 6 § to 14, we the air removed only varies from 12 to 18. | LC Influence of Height. --- Assume the height” ‘of ‘the flue to , its section and the quantity of fuel being constant. ©. y section ts assumed to be .20 m.. Satis, its area’ it .O4 m ® 5 kilos of wood per hour, making 5.04 -- 125 kikes a ~ Assume a height of 10m, and Table 32 riven. Ri we 65. ‘fable 33 gives the corresponding velocity of 513m > - “For a height of 20m, ad also obtain R’ -- 1.80, and a ve- Tectty of &. 40 m. gor | For a height of 30m, R’ -- 1.91, and velocity -- 5.55 m. a cal "3 eae es I HEATING AND VENTILATION, 101 wa evidently increases with the height. the pens 2 Sea of the smoke cdl- 102.3 and Noe volumés of air per kilo of fuel are 106, 113 and 166 mec, » Other things being equal, an increase in héight lessens the © 4 as well as a greater total volume of air - Intluence of Section. --- Suppose the section to be en- eye eh : lar- the hetght ‘and quantity of fus! being donetants Aseums ght of 15 m; 6 kilos -of fuel per hour. | @a section . 18 m. square, corresponding to 6 + kilos of wood. per ms. per hour. Table 32 gives ¥y -- 1.70, and Table 33 gives a velocity of abcut €. 3. ‘fe section .30 m square; @~+-.09 -- 67 kilos per ms. Ri -- 2.00, with a velocity of about 4.57 m oo ae 40 m square; 37 kilos of woed per ms. -- a and the velccity -- 3.85 m. ‘the velocity of the smoke varies inversely as Sonera ture successively becomes 135.8, 63.2 and 48,1, it is diminished bys an increase of section, value: of air removed per kilo of wood becomes 82, 205 ) al The cerresponding total volumes are 491, 1232 ‘ane t oi he. [It is eyident that in crease of section very greatly increases the volume of air. remoyed, which variss in an even greater ratio; in our exanple, the section increases from 1 to 3, while the volume of air increases from 5 to I°, or nearly a8 1 to A. Summary. --- To increase the velocity of the smoke, burn more fuel in the same fire-place; increase the height; or di- minish the section of- the flue. ‘To increase the temperature of the smoke, burn more fuel; or diminish the height or section of.the flue. To increase the tctal volume of air removed, burn more fuel: though this is only mederately efficient; or increase the height or section of the flue. Increase in height causes but @ slight increase in the volume of mink, but an Oareerent of |} the section is very efficient. The volume of air removed per kilo of fuel is diminished dy burning more fuel in the same fire-place, although the tctal ‘volume is increased, or by diminishing the height or section. 'Henee, the sections of aspirating chimneys. for ventilation should always be as large as possible, without impairing their (draught, if it be desirablg for them to act economical ly. On the contrary, in chimneys for mee purposes, one seeks to re le z Cy FY vide = “HEATING AND VENTILATION, | 2 “102. andes the draught, which its always more than sufficient; f4xe, hence, flues should be rather small, which tends te beth in- | erease the velocity and better ensure: a good draught, as bef- tated. “Still, if the proper limit be passed, the flue is Wd), the’: flow of the smoke is obstructed, and the draught ped. Also, the same thing in another form, a certain*min- Rl fuel ust be burned to vroduce a sufficient ein. section; ting fine eon may be-n er if the change in height more than con-. onde er the velocity of the smoke may be lang¢ In such a case, the final result can- ; a NS the yeloeie tog corresponding to the ag oles conditions proposed. ee On | the. contrary, if the height were increased and the sect +> “ion diminished at the same time, it would at once be known tha Ais the velocity of the smoke would be increased. These distinctions become very easy, when one clearly under- | ‘stands the result of the influence exerted onxthe mexxia act - ion of the chemo by seach element considered. mae ae a here i“ ; : . A ing 33 2 , by RP ae . p aa ets ais 1 ER es yt oA = dg . ee Pig mT is eae ae gt ata a G. AND LAPEON Gee 103. is avout 100 i& this case. The walls of the fire-place then ‘padiate .26 X 3.60 X 100 -- 80 calories, making the totadk quan tity of heat radadated -- 450 + 90 -- 540 calories. Then six per cent may be taken ina general way, aS reprs- senting the ratio of the heat radiated, to the total quantity produced by the fuel. ae | Heal lost through Walls. --- As the room reeeiyes heat from the fire-place, it leses all the heat passing through the win- dows and the exposed external walis, the ceilings, floors, and the walls or partitions separating it from adjacent rooms. It is necessary tc estimate the quantities of heat thus lost which may be considered apvlicable to most practical casés. fake a room of ordinaryd dimensions, 4X 5m, 2.0 m, high, with two windows having a total glass surface of 5m.s., ©6x- yosed to the extarnal air. Exposed wall surface -- 11.20— 5.00 -- 6.20 ms. (being one end cf the room only.) Floor anc esiling each -- 20 ms. Internal partitions er walls -- 328. 20 m. 8. We will assume the room beneath it to be heated, so that ne heat passes through the fleor; the room above is not wa, pmed , heat escaping through the cetling; we assume this less to be one-half what it would be, if the ceiling were exposed to the external air. Also, one of the adjacent rooms is to be warmed, the others not so; the surface of the partitions between these cold rooms and the one considered being about 25 ms. Half as much heat passes through these partitions as if they were exposed to the (2 PAPO POR Ee lila Tei So EE UR ek fee ak ea Se nae ea RIN Ae Le sl SRR ee SOM Monee ane EE an Sa ee Ra " . . ; ' Mn aM re ie WP we Sar (Smmeer Paya fpre vd §; ‘al re Dey “104 abements on page 19 or. cL Tables 4 and §, the coeffi-| tty are 2.55 for glass in. windows, and 4 - 50 fis bh eee Hence, the quantittes of Ke eo ORT =) OY. = 3 9. 50(7 ” @). q: oun ar - OY. 50. 877 Te whey were of brick or " Bi Vee would become }. 28, 1 ot sensibly influence the final result. ). ' Ren pis tla ner 4 a areca & capacity of 56 mc. aged Anieresnen: the ratio between its externa! sur- 7 and its capacity diminishes. The surface determines the sane of heat, so that this is relatively less in regard te the eapacity, as this increases . But larger rooms being warmed with greater ‘difficulty than lamba) ones, we sha! 1] retain in vart cases, the expression C(7 - @), as representing the heat % lost through the walis, being at least an approximation. _ ‘Equilibrium of Temperature. --- After the establishment of the régime in the room to be warmed, the quantity of heat fur- “ntshed by radiation from the fire- -place must equa! the quanti- ERT ORR ace - Burning K kilos of wood. per hour, the heat produced by the fire-place -- .06 X 3000 X K -- 180 K calories, according to the preceding. ‘The heat lost through the walls, etc., -- C(7 - 8) calories, © being the capacity of the room in mc.,7=the internal, and getne external tempsratures. fo this must be added the heat required to raise the temper- ature of the air in the room from 9 to7. In consequence of the draught of the chimney, the air is changed several times per hour, the tctal volume of air removed depending on the padraught of the flue, i.6., on its dimensions, and on the quan- tity of fuel burned. Mach kilo of wood requirés a theoretical minimum of 3.3 mec. air fer its combustion. Let 3,3(n+ 1) -- the velume of air actually removed per kilo of weed burned, and the © total volume -- 3.3(n+ 1)" As the specific heat of air is .312, to raise the temperature of that quantity of Got PORES PO OEE. 0, Seay ae ama, ih £f ss WA oa SeBn iS Tas Sanne Seay nak Seuhe ATS oa L ae 4 yes pee. ‘HEATING AND VENTILATION. “108, Seti X3.3(n #1) K (7 - 0) -- xx@@guxdxxx - (Oy calories are practical ly Ai all ; Decree of heat yes we have: 3(n+1) Kc (7 - 8) -- 180 K. 8 ®; K-- _-_7.@ ___, a 180 - 1.03(R ® 1)(7 = @) *° res modification, if the fire- place is inlet, supplying air directly, without hoon. ebLy. as: Percin Hie preceding equations, it is is increased, the greater will be the oy i. i a greater EA pe of fuel will s prevent Haan idhoen that 100 mec. of air per kilo of wood is peiieay necessary. This quantity should then be approximated “as closely as possible, but never reduced. ‘Even under good condttténs, wood is net a good fuel, with an elevated externa! temperature. This is proved by graphical Table 34, in which the horizontal scale represents the differ- ence of internal and external temperatures, the vertical scale being the value of the ratic Kt C. The three curves corres- “pond to the case of no air inlet, to one supplying one-fourth the total volume of air, and one. furnishing one-half. Thus, with no air inlet, for a difference of temperature of nol y 4.6, the ratio Kae -- .10; a room having a capacity of 50 mc. would require 5 kilos of wood. BExrxhwux, To raise the temperature of the same room 8, 8 kiles of wood are pedal K+C being .16. Béyond this, the quantity of fuel, increas _wery rapidly for slight elevation of Lemperature, and it a “tet possitle to raise the temperature 6, by the use of any quantity of wood, As might be expected, with special inlets for air, the fuel igs better utilized. With 5 kilos of wood, the temperature is — as for ina this: intet fee - J = 7 . ? t — 7 es : Aa * : 4 oe 7 F - Ff mp fe ip ts af + Ys to : v ri a wee ee hae YF | 7 106 “the: inlet suypl ies 1-4 the air, T 4 Lf it sup-, ty if the: RO of fual in kilos ‘exceeds 1/10. the cap- he ogee eh mc¢., &@ considerable quantity ef fuel is se without producing any material improve- ave assumed the dimensions of the as to ee. the most favorable en OL per kilo of wood. + night. be slightly higher reced since a Ghote: kind of fuel or the room might ‘be occupied, the ration aiding that of the fire-place Tri. Pom. As chimneys almostaiwx always Co has kilo of weod, the increase in 28, co ther, veaee only furnishes a moderate quan- of heat, : ‘as found by experience, unless the fire-place be vided with special heating apparatus and inlets for air. “Without. these, one can only become warm by approaching the fire-place so closely, as to be exposed to the direct radia- tion of the fire, the average temperature being but slightly elevated, producing hurtful results, the portiens of the body exposed to the fire being strongly heated, while the gthar re- mainder remains in a cold atmosphere. a» This. is worst, nearest the fire, where the air is . heated by radiation and ascends, being replaced by the cold air coming _ from the doors and windows, which moves along the ficor tow- ards the fire; the feet are therefore cold, ree the head hot, which are not hygienic conditions. Special inlets for air and openings for Ve emission of warm air from the heating apparatus diminish the admission of cold atr, elevate the temperature of the roomi( which favora- bly influences the draught), and produces a more equable tem- perature in the room tok be warmec. 1) og . HEATING AND VENTILATION ve 107. : ARRANCEMENT OF FIRE-PLACES FOR WOOD. | THRORE ICAL FORMULAE. . “Formulae and graphical tables have been established, which ‘a conditions for the action of a fire-place for wood, | P quantity of fuel burned per hour being emperature in the room was arbitrarily perature. actually depends on the ca af this. eee the relatin room; 0 -- temperautre of the eee airs ee dete y of fuel burned; 3.3(n--+ 1) -- volume of air removed per kilo of fuel; CQ a= capacity of the room in me. v¥ -- velocity ofr smoke in’ ‘the flue, and s -- sectional area of flue. We obtain: ties 3000 | (1). Bare ve L734 .86 nn. Le ROO LY aoe rk ; (2). a 3.3(n + 1)(1 +* at). Lea 4 , a(t — 9) Ree h dat): Cay. The effect Ne plunging winds, and of the depression in the room being considered. Finally: [.312 X% 3.3(n + 1)K +chc7- - 180 K. (A). Th at t at In the aust equation, .322 is the specific heat of air, rel- ative to its weight: relatively to jts volume, it varies with the initital temperature ©, beecming .312 +-(1 + at). By means of these four equations, we shall preceed to deter- mine the relation, which sheuld exist between the height of a chimney, its diameter, and the capacity of the room. Conditions of proper Action. --- For a chimney to act prep- erly,in all weathers, the velocity of the smoke must always ve sufficient to ensureaz a good draught, and prevent the return of the smoke: stillg, the volume of air removed per kilo ef fuel should a1waye be the same, reduced to the minimum require red for good combustion, t.e., to 100 mec. per kilo of wood. he draught should be reduced as much as possible, so as to mot consume fuel uselessly, and the velocity of the smoke should not fall below a certain value, this being the deuble problem for solution, which must be done to realize perfect action at all temperatures; unfortunately, this is itmpossibvle. pS RI aS UE A iy ot SEL RE Sa Oa a any eG, Seman CNM WARE AG rig a Sut caSM ea Loe le gd np eet ; Te alba bier ee a a Shr eee PAS. ere oe HEATING AND: VENTILATION, 108. But a gmail quantity of fuel is burned in warm and sultrv weather. If the dimensions of the chimney are arranged so that the velocity is sufficient in this weather, and the vol- ume of air be reduced to 100 mec. per kile of woed; as the ex- ternal temperature becomes lower, more fuel must be burned, producins a gréater velocity cf the smoke, more than is re- quired for draught, yet the volume of air per kilo of wood Will/diminish, and the combustion. will ‘be less efficiently maintained. Uf the dimensions be so arranged as to remove 100 mc. of air per kilo’ of wood with a sufficient velocity, the chimney will properly utilize and economise the fuel in cold weather; . but the yvelocttv is diminished in warm weather, requiring an excess of velocity to be provided in cold weather, Besides, the volume of air per kilo of wood tnereases as the external temperature rises and less fuel is burned, so that the fuel is used with less economy in mild weather. Since less fuel is then used, this is of slight importance. Hence, if it be desired to reduce the cost of fuel to the amount absolutely necessary for warming, as the temperature rises, a suffictent velocity of draught cannot be had, and the chimney will sroke. There is no choice, and the second solution should be adop- ted. We shall arrange the dimensions for chimneys burning wood in accordance with the 'two conditions: l. That at 0; for example, using a quantity of fuel assumed to equal C410, 100 mec. of air shall be removed per kilo. x This value C+ 10 is adopted in consequence of previous remarks. The elevation of temperature has been found not to inerease in proportion to the fuel burned. A time may come, when the temperature is scarcely elevated by the combustion Of great quantities of fuel. Practically, even in the coldset weatner, not more than C +10 kiles of wood are burned. 2. On the contrary, the temperature of 12 being about the highest at which a fire is. required, we assume only half as much fuel, or C-+ 20 kilos to then® be used. The velocity will then be detarmined under the most unfavorable eocndittons, being the least found for the smoke in the chimney. tf eufft- etent in this case, ft will suffice in all others. Relation between Dimensions of the Chimney and Capacity of the Room. --- First assume @ -=- Of making for this case, ‘ bath ae 1-2 YOO" and kK .- C+ 10, in accordance with the pre cading. By of equations (1) te (4), we easily obtain:: 4. bos 104.6; . vy) -- Avie ges bh — 1.17) a 1.50 d 4.0485 h n with the second case, substitute 4 Ty gol A a HEATING AND VENTILATION, 109 for the Tests. the following nearl equivalent expression. Pies a - -- 2 45 \/(h— 3.42) ad . AG Oa O45 h s | Finally, c 2+ 643 8)/_ (h ~ 3.42) a _ (a). on i ees ULES 1.50d+.045 h i isa equation expresses the desired Sagngdeieont between the aAe Le -= 42 ‘assuming K vy eae The value of C be equal to that just found. . Introducing these val- equations (1) to (4), the four unknown quantities 7, 1%, no and vy may be determinied without diffierlty, though this rma. y ‘be. simplified, as will be shown hereafter, in‘treating fire- places. burning coal, ome -- 14.6%. t-- "7. 8: n+l -- 182 » Wve -- AO, ———ww ee yh 94 (h — 3. 48) 3, (b). 150 a+. O45 hh ats Choa is evidently less oe in the first case, ee ratio being 1.94 ; 2.45, or-the velocity at 12 is sensi- bly equal to 4S that. at On a ay PRACTICAL RESULTS. Graphical Table. --- We have just determined the necessary relation (a) between C, h and d, that thes chimney my proper- ly aet at low temperatures. This equation may be put in the Agitering se | a, ees Che ee ti 5O Cc a ‘ 1413820 a” : : te lo SEGAGO Ge O48 Ce “which determines the height, if the capacity C of the roon, aa the side d of the square flue are given. Graphical Table 35 is based on this formula. The horizontal scale corresponds to the capacities of rooms; the vertical scale gives the & height of the chimney; each curve is applicable to a sids or diameter of flue, varying from .1@6 to .44 m, “Also, the value (b) ef v", previously found, permits the draving of the dotted curves, which give the velocities under unfavorably conditions, with the external eee re: at 12 for a determinate height and diameter. Some examples will illustrate the use of the Table. Example eae Capacity of the room 100 me.: height of chimney 15 m:; required its side. _ Aseend a youriesl through 100 mc., taken on the horizontal scale, to its intersection with a hortzental through 15 m. This point is a little to the left of the curve ford -- .30 mM, So that the side of the flue is between .28 and .30 m., 6aY about .30 m, The same point alse falls a little belew the dotted curve tah sttRelouals ry a fa a ae ee eh ae tile 4 Fag hye ~ fs RRATING AND VENTILATION. 110. ng the velocity of the smoke about 3.4 m, with the exter- temperature at 12, bupning 5 kiles cf wood per hour. In eo weather, During Te kilos of weed, the velecity would be BF 4 -- 4.25 m Such conditiens: are excel lent. Pome eeqgg of room 180 mc.; a minimum velcci- epmeumed necessary to produce a gocd draught Required the minimum height of the ie \ iC age hredeh 120 mec. to its intersection with -eurve corresponding to a velecity of 3.00 m This on the heritontal threugh 10 m., the required tis alse’ nearly equidistant from the curves for ee 38 m5 the side of the square flue should : Mastiddns. We lessen ab eintenn velcity of 3.00 m, ly for. large chimneys of considerable diameter. A ve- f 3.8 m. would be preferable in the present case, be ebtained by making the height l& m., and the side tes indicated by the Table. Lobe: things being equal, increasing the height ef the chin- ry permits the reduction of tte diameter, and augments the Bsleciuy of the smoke. - The results given by the Table, as well as those of the for- mulae from which 1t ts dertved, must not be considered abso- lute: the assumptions are averages, and the results thereby /obtained have merely that average value, from which ene should net depart too widely in the construction of chimneys. - Cireular Chimneys. --- The graphica! Table is new to be 4 Berns to chimneys of eireular section. / In equation (a) fer C, ‘if the section be circular, the sec - tional area s would be .72854 ad instead of d~, the side and diameter being equal. Other things being equal, the capacity © must then be reduced to .7@54(,/ if the section be circular rae ef square. This reduction ts made on the lewer horizenta!l scale, which gives the eapacity of the room for circular chimneys. DO eesns's 3. +-- A chimney is 1S m. high, .22 m in dtamete, ‘being circular. Required the capacity of the room, which may ‘be warmed Dy it. : Follow a horizontal through 12m. to the eurve ford -- .; A vertical through this peint falls between 40 and 45 mc. on the lower horizontal scale, making the capacity about 43 m.c. ‘But the velocity is too small, since the potnt of intersec- tion cerresponds to a velccity of 2.8m. at most, so that thi “Must be increagead. For the same capacity of 43 m. Ee it would be preferable te make the hetght 14 m. and the diameter 21 m., which gives a Hee} aD 4 ot g (MG AND VENTILATION, =, SAD velocity eu 00 m. vie possible solutions may be found by ascending the vertical threugh 43 mc, the velocities increa- sing, though also requiring greater heights; a diameter of .20 me -would require a great increase in height. The last’ example shows, without attributing too. great numer- + 1H po to its indteations, that a superior limiting dia within which one must remain in order to obtain ate “phia. faee ie. Neueitanc to po eahar. and vote especially these burning wood, are bine the last eis fer a given capacity, we find that a euf- pfiteient. velocity and an assured draught can only be obtained “by ming the chimney about 14 m. high... This explains why the sught ofa ehimney is not a lweys certain, unless a much : reater quantity ‘of fuel is burned, than is required for warn- ing» ‘the reom; requfring the room to be ef censiderable size, or the. fire would become intclerable. fhe evil may be alley - fated, as previcusly indicated, by special inlets fer air, or Oy: ventilators; ‘but one cannot Ce certain ef everything. It ‘igs an unfortunate and inevitable result of our ordinary fire- huahons valida large openings, especially when burning weed. ’ : we ch aey eae ‘ Sa a x BR: "SY bee ® “Ite 48 x BEY Ie os a 2 HEATING AND: VENTILATION, _ FIRE-PLACES FOR COAL OR COKE. ORETICAL FORMULAE. = Tee uy a al Fermulae. — -- As in case of fire-places burning rmutae will be given for determining the temperature ame) ‘he volume of air removed, and the velocity of ke, the dimenstons of the chimney, and the quantity ef ned being known. First, assume that ne ‘plunging wind .1 deppesston exists. . ure of Smoke and Volume of Air removed. --- Same in case of wood. +t -- temperature of the smoke: ire of the recom? @ -- température of the externa! : v wat oe Be yy Bera ih ath re riiat ita E lo of ceal theoretically requires an gverage of 8 mc for its combustion, as shown on $age*: ; After. into smoke, it requires 2.79 calories per degree of its temperature. Hence, 2.79(t - 7) -- the quan- at absorbed by this first quantity of air in pass ing % a Scaping combus - mer quantity, -- @n me. passing from7to t, as 8 3 calories per degree of elevation S$, as an averages, equating to that received by the smoke, we have: he ee go / Ge Men SR Gh tice a3n + 2.79 The quantity of cold air entering the chimney equals the Quantity of warm air leaving it. cae | Volume ef cold air -- tear 6(n+*+ 1) K, K betng the number Of kilos of coal or ecke burned per hour. _. Volume of warm air -- 3800 v gs per hour at temperature t. _, Its volume at O°-- 3600 sv. Equating this to the volume cf ae | 1+ at ecld air removed, we have: ee 7 (n+ 1) K -- 3600 s v (b). | 1 + at. | i. Velocity of the Smoke. --- The equation is the same as for | chimneys for wocd. - | os | v -- : 2g ha(t - 0 (¢c}. ea (804 OW Sa) CL a x Assuming no plunging winds or internal depression te exist. 4 Simplification of Hquation for Velocity. --- These aré sim- tlar to those for waaax chimneys fer wood. , In the equation: for vy, replace Vt - @ by its practical (a). ONG ee: “HEATING AND VENTILATION. ° 113. “einivalent | ,O68(t - @) + 3. 30. Making 7-- wb and GQ =. OF ae under ayerage conditions, | we have: =. Ethane | FO) et Caeae pi iinace 2 968 Ga ne i hey es Sarat Perit ee Ae be 1 15° Hy, uting 2.3(n Bl)(t — 164 “for 2.79 42,3 n)(t~ 18) cn (a) emhick does net s Nabintadh ti change its value, n ; is ae, i, its Sv S| | shot amethly haneean the final result, obtaining: | i NEN -O125 Koes 4.5606 Ril + Fe ESS Y Mele ne hoe Rese a es | These three ‘aquations with the one previously adopted, | R-- h aes | i 1504. O45 h yd i | permit the soluticn of all qeestions’ relating to the acticn of - chimneys under the assumed average cenditiens. Examples of their applicaticn are unnecessary, as they are employed exact- ly as in case of fire-places burning wood, where the different cases were fully considered. These solutions will be facili- , tated by the use of graphical tables, whose construction will be explained, GRAPHICAL TABLES. ae 2 Construction of the Tables. --- The relations between the Abe tee the height and section ef the chimney may be deter- mined’ by means of Tables 32 and 38. The first gives the rela- tion between the height, the side, and the quantity R -- aes Rage which serves as an intermediary between ‘Vi. 50 + .045 h 9d . the two tables, and is the same as for fireplaces burning wood. The second gives tite relation _ between the quantity R, the velocity, and the quantity of fue} - burned per ms. of the flue. Both tables are used in exactly the same way as for wood. : | Use of the Tables. Example l. --- Given, the height, sect- fon, its side, diameter, or mean diameter 4 s%ep, (if the flue be neither square nor eérculan), and whe: eee Y of fuel = aG-Rs i ’ “ ayn aia Vea os ee cae HEATING AND VENTLDATION, 114. burned per hour; required the velocity. Let the height be 20 ane eee os mM; side .2° m., section .O8&7 ms.; 4.18 kilos of coal per hour, -~ 4.18 *~087 -- 48 kilos per ms. On Table 32, ascend a vertical through .29 m to its intersee tion. with a horizontal through 20 m., which cerresponds to R -= 2.08, falling between the curves for R -- 2,00 and 2. 10. On Table 36, ascend a veritcdd through 48 kilos to a point conpesponding to R -=- 8.08, just below the curve for R -- 2, 10 @ horizental through this point gives about 5.50 m. on the vertical scale, the required velocity. Morin found this velo- city to be 653m. ‘by actual experiment. If the Lémperature of the smoke were required, it my be found by equation (2); the volume of alr ts determined by eq - uation, (1), replacing t by its numerical value. in thts cas found to be 1271 mc. by the formula, OP R23) ane. ay experiment. experiments were mde under conditions, differéng Peers om those assumed as averages. The externa] temper .f ature was” TS jnstead of 0, the internal temperature being 20° is instead of 15; stilt, their results show that the values given es 32. and 38 are practically correct, even under slight ly different conditions. Example 2. --- Height 20 m., velocity 5.50 m., side . 29 m. and’ seetion . O87 m. 8.3 required the quantity of fuel to be burned to produce this velocity. On Table 32, 20 m. height and .2@ m. side give R -- 2.08. On Table 38, 6.50 m and R -- 2.08 give about 48 kilos per ms. Then 487-087 -- 4.18 kilos ef fuel per hour. ee ag 3, --- Section .087 ms., side .29 m, velocity &. 50 Pi kilos of coal per hour; required height h. On Table 36, 5.50 mv velocity and 4.18 47.087 -- 48 kilos perm s., give Ro -- 2. OB, 2 aah 32, .29 mM. side and R -- 2.08 give 20 m height. le 4, --- Given, the height 20m, the velocity 58. 50 m., 4.18 Kilos ef coal or 48 kilos per Pas - required the side A tentative process will be hegedeary. : 1... Assume the section to be .25 m Square, making its area 0625 ms. Then 4. 18 470625 -- 67 Milos perms. (For any other form of section, its area could be deduced from its meéa) diameter, according to its form, the quantity of fuel per ms then being computed). Proceed as in Example 2. On Table 32, the height 20m and side 226 m. give R -- about 1.€8. On Table 36, 67 kilos per ms. and R -- 1.98 give a velocity of about 6.10 m., which tes too great, the given velocity being &. 50 m. 2. Assume the side to be .35 m, making its area .1225 m.s, ang:.4,18 + .1226 -- 34.1 kilos. cf coal perms. Table 3.72 eae ay) HEATING AND VENTILATION, oe ET&, 32 gives. ‘Ro (2.21, fer the height’ 20m and side .35m Ta- ’ ble 36 gives a velocity of 4.95 m for R -- 2.21, and 34.1 ki-. les of fuel perms. This is too small, £O that. the true side is between . 25 and .35 mt | 3. Assume the side to be .30m., its section being .09 me. ‘Table 32 makes R -- about 2-10, for a height of 20 m and side Of). 30m... Table. 38 gives a welecity of about 5.45 m for 4.18 .O8 -- 46.5 ktlos of fuel per ms., and‘R -- 2.10, which is e231 mabe ee eee of 5.50 mM. fhe true side la pe. ter ae se | Aseume that in the same ry, “Table 32 eae a ‘constant ya lak for R, which we will age - ume to, be 2, 00, for example. | Co Om Taple 36, taking 30 kilos of fuel per ms., for example, we ebtain a velocity of about 4.5 m. For 5O kiles of fuel per im s., the velocity is 5.48 m For 70 kilos of fuel, the velce- eity is 6.30 m It is evident that increasing the quant itu of fuel buried also increases the velocity of the smoke, as in the case of wood. By means of formula (2)., ihe corresponding femperatures of the semeke are sasily found, which are 70. “a 997, and 124, By formula (1), knowing the temperature, the value of n+ | 48 easily found. The volume of Gold air removed -- 8(n * 1), which gives. 442,72, 289.84 and 223.36 mec. per kilo of fuel. Henee, as the quantity of fuel inereases, the volume of air per kilo diminishes. . The total volume of air removed, being the product ef the number of kilos ef fuel by the volume of air per kilo, becomes in the three cases, 13280 s, 14486 s, and 15832 s, s being the ‘sectional area of the flue. The total volume of air then in- eréases with the quantity of fuel, theugh more alowly. Influence of Height. --- Suppese the section of the flue and the quantity of fuel te be constant, the hetght of the a cat being variable. Let .20 m be the aide -O4 ms. the sectton; 2.5 kilos of ceal per hour -- 286 +. 04 -- 62.5 kilos per ms.o of flue. Let the height first be 10 m. ‘Table 32 gives R -+ 1.68, ard Table 36 gives a corresponding velocity of about 5.42 m. Taking a hetght cf 20m, Table 32 makes R -- 1. 82, and Ta, - ble 36 gives a velocity of about 5.70 m. For a hetght of 30m, R -- 1.0, and 5. Bh -~- velocity. Other things being equal, an increase in height increases HEATING “AND VENT LLATION,. . oe = 118. The temperatures obtained by formula (a) are 130, 123 and 1105 fer the three cases. , The volumes of air per kilo of fuel are 212, 228 and 234 mq The total volumes of air removed per hour are 529,.571. and RES ime. ence, an ¢ncerease in height diminishes the temperature of the smoke, removes @ greater velume of air per kilo cf eos), and | also a greater total volume. * Influence of Secticn. --- Suppese the height of the chimne ; quantity of fuel tec remain constant, the seeticn being Bicosre vals enlarged. Let 15 m -- height, 3 kilos of coal te be burned per hour. 9” . Assuming @ section .}8& m. square, its area ts .0324 ms. 3s7.0324 -- 92.5 kilos of fuel ver ms. Table 38 gives R -- 1.70, and Table $6 then gives a velocity of about 6.80 m. make &® sgction .30 m square, area being .0O8 ms. Then_32°: ~O8 == 393.5 kilos per ms. We then find R -- 2.00, and 4.65 do -- the velocity. | Take a section .40 m. aquare, area .16 me. Then 13.5 kile: ef {uel are burned per m.s.; R -- 2.18, and 4.05 -- velocity. Henes, in general, the velocity of the smoke diminishes as the side ef the flue ts increased, other things being equal. The temperatures are 1€9) TE and 38.4. An increase of sec- tion then reduecss the temperature. ; The volume of air removed per kilo of fuel is 15€, 386 and PLCOAMU eee) . The total volumes of air arw# removed aré 47 B, 115 and 34680, Hennes, an increase of section very rapidly increases the vo] ume Of air removed. oummary, --- We find that, in heating with. ceal or coke, as ith wood: To imerease the velocity of the smoke, burn more fuel in the same iire-place, increase the height of the chimney, or dimin ish 1t6 secticn. To inerease the temperature of the smoke, burn more fuel, Himingsh the height or section of the chimney. To imerease the volume of air removed, burn more fuel, though this vreduces only a mederate increase of draught, imerease the hetght. or section of the chimney. The inereagé of héetght is not very effective, byt the increase of. section is very efficient. To diminish the volume of air removed ver kile of fuel, nore fuel tn the same fire-place, which does nop prevent Sotal volume from being greater, or diminish ‘the height gection of the flue. ‘ : Congequently, we obtain results for coal cr coke, similar to mOSe Tor wood, i.e., in chimneys devoted to heating purposes, a HEATING AND VENTILATION, DA? where. the. ‘volume of air removed should be reduced as much as t at Bak the section should also ue as small as may be ee Tata ting chimneys, where as taken a vol- ef al Ap. to be. removed @s° possible, should have sections S large 8 consistent with the nee ese lhy of ea aace a suffi- “Tf both influential Faerie, vary. at the same time, the re- be hea effects may intensify Or: neutralize each other: in- 288 in height tends to inerease the welocity, which te’ di- abet by an ‘Increase of section. ‘Either effect my result, according to the ratio between the enlargement of the secticn. and the increase in height. On -the eontrary, increase in height and section both tend te inerease the rolume of air removed. ‘ The graphical Tables give the results cf various Leen tee nodifications with accuracy and great rapidity. — & itera te wi 2 “A “PRATING AND VENTILATION. Ee. ARRANGEMENT OF FIRE -PLAG SS FOR COAL OR COKS. CRYAORET ICAL FORMULAE. : | bénipl ete Formulae. --- The preceding calculations have egs- ‘autia ed the formulae required for studying the acticnrof a fire place, under average conditions of working, arbitrarily assuming the internal temperature ef the room. to be 1E. mi, OLE ‘peality;. as in warming with woed, a relation exists he- ‘tween the heat supplied by the fuel, the capacity of the recmn, and the tbamperature of the air tn’ the room, 5. Bm: oying the same notation as for fire-places %urning wood, 72 ree ‘equations connecting the temperature t of the Pnal- erates: 2, the interna] temperature Sens dal burned per hour, and finally the ee tig Ly, eat ‘the emeke. ae These ge Bee ee ye oe be =o Vik 7FOOO as WB Viggo. eyes ; re (] ). ah a acre ea a cs ale Da 4 EO Hes SCN) ge NS (2). Oe Bin ee Ly h we at) | 1 ey + hat = a) Sth JBh0) + at) C33 1) 1.50 + .045 had s pain he PT of the chimney, @ the side or mean dian- jeter of the flue, and h the height of the chimney. Zquaticn (3) takes acecunt of the effect of plunging winds and of the internal depression. ‘The equation into which the capacity of the rcom enters is; nate F Cin + DK C|(7 - @) -- 840 K. (4). l+aQ In treating the equilibrium of temperature, we have seen that this relation must be establéshed by equating the heat loreduced by the fire-place to that absorbed. by the air in pa ging frem 0’ to/ adding that lost through the walls cf the oct .. BY @ process of reasoning similar to that emploved in the case of wood, the heat utilized by radiation is found to ve ebout .l2 of that preduced by the fuel, or -- .12 X 7000 -- an averaze cf 840 calories per kilo of coal or coke. By a@ rude approximation,#” sufficient fer practical eparnoae we found the heat lost through the walls to We -- C(7 - aie: 4 for the internal and external temperatures and 9. The heat aveorved by the air -- ,312 X ®(n4 1) K#+(t + at), as May easily be found by reference to the statements made in considering the arrangement of fire-places for burning wooed. These explanations. elucidate the establishment of equat. (4) Conditions required for proper Action. --- As previously Stated, to prevent useless comoustion of fuel, the volume of 5 ee pal snbiv ¢ ee La « i * % EEATING AND VENT ILATTON.. 119. air removed must be reduced as much as possible, -though a tain velocity is required. In accordance with reasons previously given, the only mode of reconciling these two conditicns will be to reduce first the volume of air removed to 160 m.c., which is strictly nec- essary for each kile of fuel, with an external temperature cf ; assume that C #20 kilos of fuel are then burned, C being the capacity of the room in m.c. CuO was taken for wood under similar conditions, but it is.already known from the ex- amples studied, that a certain quantity cf mineral fuel produ- cés effects Pa cies ili similar to twice the quantity of wood. On Table 37, for chimneys burning coal, tface a curve simi-. lar to that on Table 34, for chimnevs burning woed: it is ob- tained*Sy laying off the differences of ena af external temperatures, resulting from heat on the 1 seale, and the ratio Kx € on the Peeersey scale, er the ratio of the number of kilos of fuel to the capacity of the room in m.c. this curve is computed by formula (4), of which it is the graphical representation.; a comparison with Table 34 shows that with mineral fuel, one ¢an obtain-a much greater el eva- tion of temperature in. the room, before reaching the limit, where the fuel is wasted without warming the room. Waving assumed. this first condition, we should then deter- mine the velocity under the unfavoradsle conditions eof an. exter nal temperature of 129 when only C440 kilos cf fuel are use. When the dimenstons can be so arranged as to produce a suffi- efent velocity under the last conditions, it is assured under the former. Relation vLetween the Dimensions ef the Chimney Capacet of the Room, --- From the preceding, we will assume in the four equations preceding,; 9 -- O, f(n +1) -- 160, and K ast. Theny -- 12, t -- 164, - ay be oe faa) La | 60 . 045 h wd and finally, © -> 888 3g d(h— 2, 83) a (a). “ 1,50 d #045 h which gives the relation between the height of the chimney, fts, section, and the capacity of the room. Next determine the velocity when @ -- 12° in-the most unfav - orable casé, other conditions remaining unchanged. (Thesé calculations are only approximate, yet sufficient for practical purposes. ) In the four general equations make Q «- 12° and K.--.C_ Equation (2) gives v’-- &(n 21) K (1 + at) 40. 38600 s Whence; t being about 100. vy" -- (nt 1) } 320 8s { ; £ A ee ao oe HEATING AND VONTTLATION Prom equation.(3), v" -- .24)\/(h -.3.42)(t - 12) 1.50 +. 045 hx * 2 ss Consequently: (n+ 1) K -- .24 (h — 3.42)(t - 133 . 3207s" 1.50 - O45 h ‘x » Yeplacing the term .85¢1 + at), which expresses the effect of pro rine tne minds, by 3.42(t - 12), which is practically equiva- Tent, for the assumed values of t and 0. |. From equation (1), replacing 2.70 by 2.30, which is vessid! a ne nis so large, : eager no¥1.-- 7000 ~- 3044 By, 300t Meee! tia ga' Ba Pron the last. and the next preceding equ: ; we have: Pees | h ~ 3.42 Ke ( whence thie! po" s*(h — 3.42) a | on’ the other hand, for the assumed value of K, and the rela | ‘tion (a), found for an externa] temperature cf Of which gives Lea Ai of C, we have: |, . oi et 22 nee s KX (h — 2.26) a 1800 1600 .. EO a .045 h With eurficient approximate accuracy, we may replace h <8. 2 by 1O(h — 3.42) # &, to simplify the- calculations, and sudsti tuting that value. tor K in oe expression for tt l2, we fin i tas Sa) ieee Be 9\523 -- 96! Therefore, for boa 38. 3. a B(n & 1) -- 290 m.c. Tit is now. easy to obtain. from equation (4): Wepea Aine Te 2 , whence 7 -- 18. 4. i Sa 8 640 - 2.5 3 Be ae Ge. Dae ys | [Introducing the value cf t - 12{ found above, into the equa Bion for.v",, ve: vy" (ieee Dy (ti > 2 ..) 2. 36/th — 3.42)4 .50 4+ .045 ha -50 a + .048 h This value ts evidently less than that ef v’ found in the first case, the ratio of the two velocities v’ aie v* being 2. 36 += 3.08, which differs little from Ane, hich was also obtained in: the case of warming with wood } PRACTICAL RESULTS. Graphical Table. --- From the relation (a) between the cap: city C of the room, the height h and abetlon Ss, and its side or diameter d, we may. conclu@e that h + 1.60 c*d + 1702738 a Geaaees GC? <= > 045-C * By which the height may be comput ed, when the capacity C of the room, and the side @d cf a sjuare chimney, for example, ar given. Table 38 ig computed by means cf thes formula. The «@ HEATING AND. VENT I LAT LON. 12) horizontal. seale represents the capacity of the room, »the hetght of the chimney is given on the vertical scale, while each curve corresponds to the side oF a ‘8quare flue, varying from. 1@.to...40 m. ! Also, equation.- Capacity of room 100 m.c.+ height of chimney ; Hed dae of the flue. thro. TB met this. “point. ray cobresvends te ig between the curves ford -- . 24 anc eee. this int also falls slightly below the der vecs curve cor- g toa velocity of 4m., consequently, the vedocity yout 3.60 m. under the assumed unfaverah @ conditicns an external temperature of 12) and taking account ing winds and a depression, when 1090-440 -- 2.5 kiles of fuel are burned. In eold weather, the velocity will be about 5 X . 904 4 -- 4.90 m., Surning 100-¢“RO -- 5 kilos cf fuel. These condi- tions dae resvend to a very gocd action of the chimey. axample 2 --- Capacity 120 m. e.* a yvelocigy.of 3.5 mis here considered necessary to pré6duce a good draught, even in sultry weather. Required the least height of the chimney and bts corresponding section. Agseend the vertical through Lobe. a. to its intersection with the dotted curve, representing a velocity of 3.5m. This Peint nearly lies on a horizonta!} through 10 m., which is, the required height. The same point aleo lies between the curves ford -- .26 and .30 m, so that the side cf a square chimney sheuld be from . 29 Lo 30 Ms OMB Ae the remarks made in considering a similar case for fire- ‘places. burning wood, are applicable to fire-places using coal Or coke, ‘espectally. those relative to the degree of rigor, with: which the results of theory are to ‘be applied. Circular Section. .--- It remains to extend the application ef the Table to flues of circular secticns. : “In equaticn (a), for the value of C, it ts evident that the area s ef the secticn, here assumed to be circular, is .7854 ad? The area cf the square section being d* other things being equal, the capacity C must be reduced to ST ebA of its former ‘alue, for a circular ssecticn. / This reducticn is mde on the lewer horizontal scale, which gives the capacity ef a room warmed by a chimney of cireular section. ‘ae . & € a * . \ HEATI VG AND VENTILATION. Ri Oa According to equation (b), the velocity v" is not modified ‘by the ehange of form of secticn, if h and d are constant. Leb) Exar le 3. 4+- A circular chimney is 12m. high and .&e2 n. in diameter; required the capacity of the rcom warmed by it. Amamndxaxxerxiexixkoxizentai | / follow a horisental through 12 m to its intersection with ‘the curve ford -- .22; a vertical threugh this point gives about Kem. ¢..on the lower horizontal s¢ale. The intersect ton ‘is also very near the curve for a velocity of 3. 5 ™m., 80, that s velocity may be considered ample. the, velocity required to be increased, the height should i increased, ‘and the diameter of the flue. varied according! y. Ascending the vertical through the capacity of 52 mec., we may ‘obtain alt: possible solutions. This shows xka how. little is ‘the vriation cf the required diameter. ie already stated fer fire-places burhing wood, a certain eeetion of the flue corresponds te a room of given capacity, and this eannet be sensibly varied, without giving the chimney an excessive. height, or producing a danger of tnsudficient ve- locity... This explains why ehimneys are regulated with such great difficulty, when the section originally adcptéd, was net the proper one. ee a : eu At a> =. 3 4; Ch: 9 vo “HEATING AND VENTILATION. Mae 4c VENTILATING FIRE -PLACES. © CALTON TYPE. These utilize about 1/3.0f the tctal. heat from woced. They introduce and warm about &O to $0 per cent of the ats removed by them, leaving only 10 to 20 per cent to enter ‘through the crevices of the doors, windows, etc. This air en- ters at a temperature of about 34, when the external air is at Oo: The temperature in the room is practically uniform. | Dimens ions oft these --= The pipes should be. of al, rather than of terra cotta, because better conductors at, the air being better warmed by contact with them. Mst be so arranged that the air may circulate all around so as to be Nba whch ag much as possiule. - : | | 3e00 -- Fey | ‘Oot: air. ramov ed iper a doe nd. and the section ef the pipe should -- 9720, the average eloctty within ‘Th Heine’ 2.70 rn aking © #6400 as the net area of the flue, within which ae sheet metal pipe is placed, thus assuming the volume of air admitted to equal that leaving the room, and that the eas cireulates. within the flue and around the pipe with a.veloci of 1. bo m., the bed Biel Nag of the flue will then be: eo: © ae ens = os Ps 3800 2.70 1. BO e 15120 mea Grate Surface. 1450400 =* quantity of coal to be burns since experiments show that. 400 mc. ef air is removed per ki- lo ‘et coal burned. ‘If the fuel be so managed as to mae 80. kilos per ms. of grate, ite area should -- §.* 24000 nm. The total area of hearth should be about three times er Inlets for Air. --- Care should be taken to sc place the ginlet openings as te avoid the effect of the wind: it is pref- erable te arrange the ap 80 as te have cpenings on opposite BidesPivat hey bubhedingysbbisywte, athermpantngt waanxtecmrve te ty Kentitatedxundx newlthy: court sxundx emi tursyvEOXUSY ETXTAUNSXTRE - Sides of the building; otherwise, the opening mist be protect- ed. Finally, when possible, the air must be taken from wel)! ventilated and salubrious courts and eellars, so as to cause regular action and to produce an equable temperature. The duct must be furnished with a. valve for controlling the flow. The area cf the inlet duct and that cf the cutlet apening | fer the warm air entering the rcom, must nearle equalt the clear ‘hte of the flue, and of the smeke pipe, . e. £4900 mm. The inlet opening may be a little less, but the’ outlet eran ta be slightly increased. Pt Laman oe hptabiain’ ToS Wile a WE, = 7 e a a cA * ay a uA SD We rey a ao lans Ni ; 4 we Bi HEATING AND VENTILATOON. i ieee CAUSES OF SMOKY CHIMNEYS AND REMEDI7s HaReror, hese will be separately enumerated, indicating the proper -Pemedy for each; in general, the surest means of preventing smoky ehimneys is to properly arrange their heights, Becticns, the fire-places, inlets for air, quantities of fuel to be burn ed, before the construction of the chimney. Delectime imtrcduction cf Air. --- One cf the most common ‘(adetects is that of not arranging sufficient openings fcr the admission of air, during the erecticn of the building. From the requirement of having a large opening for the fire- place, © linany, chimneys remove a ee. larve volume of “ir, in com- parison to. the quantity of fuel burned. The smoke is thereby greatly ceoled, and the draught is very delicate and suseevti- le in this. kind of ‘@pparatus. If any obstacle be alse oppo- ped. WO. the. free admission of the air, a depression soon oceurs within the room; the motive pressure, i.e., the difference of the pressures in the. room and at the top of the flue, diminish a3, and’ ‘also the draught. As the velocity of the smoke dimin- shes, there is an increasing ten@ency to the formation of der -eending currents of cold air within the flue, and to a return -of the smoke. These phenomena have already been studied in treating plunging winds, sland luc currents, and tnternal de- pression. ©. The remedy ia easily fits oa tad The admission of air bdeins insufficient, ‘ample inlets must be fermed; movable sashes at least, or attr ducts may be arranged opentneg in the fire-vlace and communicating with the external air; in‘a word, the adnis- gion of the air must be facilitated. i Also, though less efficient, the diacharges is restricted by diminishing the outlet orifice of the chimney, or by contract ing the throat of the fire ys by masonry, or by a movable plate. : ! Temperature of the Smoke God low. --- The velocity of the emoke depends on the température. he draught becomes insu¢- ficient, when the quantity of cold air mingled with the smoke is too great, cooling it too much. \ The use of. apparatus for warming the air removed is an ex- eellent remedy, for tts temperature is then greater, when mixing with the smoke. Also, as in the first case, the volume of alr removed may be reduced by contracting the fire-place. Chimney too low. --- The height of the chimney is sometimes insufficient, producing a lack of draught. The best: remedy is evidently to. increase the length of the flue, to orolong it .by @® pipe of sheet metal, or ‘to use a cowl, wil oh may slightly increase the draught, ‘when there is any. wind. In lieu of anything | better, the fire-place may be contracted ! HSATING AND VENTILATION. 125. the psight and velocity remaining the Same, but the contract- lon of the throat produces a better combustion, the smoke is cooled less, and the velocity finally becomes greater. Communicating Fire-places. --- Several: rooms are each fur- nished with separate fire-places, and also communicate with each other; if a large opening be not available for the admic- sion of sufficient air to supply all the fire-places at the Same time, some will act as air inlets for the others. There is no remedy for this difficulty, except to facilitate the re- newal of the air by all the means previously indicated, or to close the conmunications. Communicating Flues, --- Single Flues. --- The smoke flues sometimes communicate with each other, and according to the mode of their junction, one of the currents mav obstruct the others. [n treating the flow in ducts, these difficulties weré described, and the proper means to be employed was des- ecribed on page . , A single chimney has been proposed and sometimes enploved, which extends the entire height of the building, reeeiving the smoke from all the fire-places in its vicinity. This arrange- ment is very economical, because occupying small space; only @ single flue requires to be swept; for thig purpose, a shest tron door is arranged in its base, for removing the soot. But this system also has many inconveniences. The fire-pl4- ces must be placed in the immediate vicinity of the chimney, with whieh they are connected by short branch flues, if econ- omy of ecnnstruction and cleaning is not to be lost; this con- dition is sometimes only satisfiec with difficulty. Besides, there is the inconvenience of communigating flues. [f all the chimneys are not used at the sane time, those with- out fires serve as air inlets, allowing a large quantity of air to enter and mix with the smoke in the chimney, cooling 1} injuring the draught, and facilitating the establishment cf G@escending currents, the return of the smoke, ete. Hence, it is necessary to furnish each fire-place with a valve, which must be céosed as soon as the fire is extinct. It is not easy tO arrangs apparatus for hermetically closing the opening, in Spite of the action of the fire, the smoke, and of rust; nor can one depend on the constant vigilance of the occupants, who should frequently open or close these valves. So this appar- atus is seidom used, and is not authorized by the volice regu- lations of Paris. | Plunging Winds. --- Precautions should be taken against the action of plunging winds, which may occur and drive back the smoke; accidental currents may be produced by the reflection of the wind from surfaces adjacent to the outlets of the chim- neys, by the heating of the roofs, ete,, and these currents HEATING AND VENTILATION. eee may Mic assume a downward direction, producing similar ef- ‘fects. We have already analyzed these different phenomena : in | peda: plunging wids. The best remedy is to ensure a good draught by asetgning proper. proportions to the chimney; as auxiliaries, there are various cowls, aspirators, estc., which afford good results, | than ‘the direction of the wind, and compelfing it to ~ othe gene hey at may be its ‘direetion, instead of cp- 7 ¥v * aF Dray (Y a eerF O37: Z a ~ HRATING “AND VENTILATION. 127. - HOT AIR FURNACES. | ia ane ~ GRNERAL FORMULAE. eg a Volume“and Tem erature of the Warm Air. --- Hot air furna- ces are placed outside-the rooms to be warmed, usually in the cellar. Whatever may be the special arrangement ‘of such an apparatus, it is always composed of a fire-pot furnished with Pate, on which the fuel is burned, of tubes through which moke passes, and of a smoke flus.; fresh air sixraniakex ought through a special duct and circulates around the ; e-pot and the ‘tubes, and is thereby warmed; the warm air passes into a hot air ‘Chamber, from which the. different ducts take it to the places to be warmed. . The points of greatest importance to the constructor are the ensions of the different parts of the heating apparatus, and of the air ducts. To determine these, it is first necessary: to find the req- uirements | to be satisfied by the apparatus. Let V -- the vol- ume of air introduced through the furnace, and VY’ that to be removed in the same time. If there be no ventilating appara - tus in the rooms to be warmed, the volume V’ which espapes through the crevices of the doors and windows, and through the orifices placed at the same level as the openings for warm aif will ‘nearly equal the volume of warm air introduced: the sligh difference observable results from the different densities of the hot air and of the air escaping from the room at 15, for ees | im the outlet orifices ees ai aced Higher than the inlet openings, an auxiliary draugk will be produced; and the” voline VT wilt. ‘Da:'graater than. ¥. The volume V- ot wath air enters at the temperature t: it mixes with the air introduced. by the ventilating apparatus, a and the total volume V’ must be at 15; a certain quantity C’ of heat is lost through the walls, the window glass? the flocs and ecsilings. It is then necessary that the heat given out b) the volume V in falling. from temperature t to 15 must heat volume V' — V, introduced by ventilation, from the externa! temperature of O° to 18: also, further, that this heat must pensate for the loss a. One must then have; — One Vin} 16) o- . a186V) ~ Vv) (1B ~70) 4.C! . As .312 calorie is required to raise the temperature of 1} m ¢. of air 1 deg. The variation of the weight per mc. with the temperature, my be neglected for the present approximate calculations, within the usual limits of temperature. The preceding equation may be simplified and written: ~312(V(t — 8) — V' (Ie = 6) -- Cc. (1%. When V or t is given, t or V may be found by this equatio pe | 2 « HEATING AND VENTILATION. 128. \ The. same “result would ve attained bye equating the quantity of heat furnished by the furnace, i.e., .312 V(t — 9) calo- “pies, to the quantity escaping from the room in the same time, {.e., OC! #.312 Vv’ (1B — 6), the tctal volume Vv’ being received from without at temperature t, and escaping at IB. . : If V -- V', when there is no auxiliary ventilation, this re- ‘lation. becomes: ee lmaVEet. 16) < Cha (ey. ‘inally, the quantity cf heat to bs wih) i ad per unit of ‘time is known to be . 312 V(t — 9)-, a quantity which we wil) © designate by h Quantity of was. to be binned. --+ Coal of average quality produces from 7500 to 8000 calories. Only about 70 per cent ef this is. practically utilized in a het air furnace, or sO00 calories per kilo. The remainder? is carriad gts in the smoke or lost by radiation through the walls, Ouete 8c. To .furn - ish the M calories required, it is necessary a burn M4000 Kilos of coal, or nearly the same quantity of coke. Wood has a balerific power of 3000, about 2000 calories per kilo burned being utilized; the quant | ty of fuel would then oe -- M- 2000, . (The. same method ig applied to cther fuels, taking 7O per cent or. their calorific power. Grate Surface. --- In furnaces under steam boilers, from 160 to 200 kilos of coal are burned per ma. of, grate, but in the | fire pots of hot air furnaces, with a quiet fire, one ahould only burn 60 kilos. The quantity of fuel reguired per baw then being M+-5000, the grate surface should be M The game surface would be required for coke, 30000 or it might be slightly reduced. For wooed, peat, tan-bark, the surfaces should be increased aAbcut one-half. Heating Surdace. --- In the fire pot of the hot air furnace the smoke is much warmer than in the tubes; the air tn contact with this fire-pot 6s colder than that in contact with the tubes; the transmission of heat is much greater in the vicini- ty of the fire pot, than at the extremeties of the tubes: — Btill, experiment proves that, as an average for the whole, in Cast {ron furnaces, 3000 calories pass from the smoke to the air, per hour and per Square metewe of the heating surface. Since M calories are required, the heating surface (fire pot and tubes) should -- M+ 3000. When metallic surfaces furnished with projecting ribs are used, thege should be assumed to transmtt bfe times as much héat, as the smocth surface to which the wings are attached. $0.4 ‘surface furnished with wings and represented by 2 {s. eq- yepl ent to a smocth surface represented by 3. “in het air furnaces constructed of terra cot&a or fire clay, ‘id HEATING AND VENTILATION. 129 only 700 calories are transmitted; the heating surface (fire “pot and tubes) should then be -- M 4700. ; The dimensions thus obtained are to be taken as minima, for en apparatus: must have an excess of power, 80 a8 to provide ‘for any event, for exceptionally cold weather, for warming a ‘room without loss of time, etc. | ' Section of the Flue, --- fhe dimensions of the flue may be caTculated by the formulae for draught given on page 7/ et se. ‘Tt is well to do this in cases of exceptionals importance: ut experience Shows that these dimensions my be determined by means of the equation p -- 70 s/H. (3), SBE being the weight of coal per hour, s the secticn of. the flue, and H its height. The weight p -- M+5000, as before. The height H is fixed in advance, usually in consequence of the height of the buildings; the section a of the flue may. then be found by the formula, for warming with coal, and this is a minimum value, which it is well te inerease in side or diameter by some centimetres, to'compensate for its eing ob- structed with soot. Tt is customary to make the section of the chimney for wood BR times as lpia as for coal, Lf the wood contains 20 per the section of the chimney ere be l Ly, eee that eluted for cceal, It is easy to justify the practical formula. adopted for de- termining the section of the chimney, by deducing it from the formulae already theoretically established. It was shown on page /3that the velocity of admission of the air is pn et ea ee by the formula: i — v! t+ 32 Gky. 268 ey = @) ltat Ver ml Fa Oy” the temperature of the smcke being t, the external temperature 6, and R representing the resistance to flow. " _ We may take @ -- 0 If s -- section ofthe flue, sv’ -- volume of atr. removed per second. [If p -- number of kilos of ‘fuel burned per hour, and V -- volume ef air practically requi red for the combust ion of 1 kilo in that time, the volume of atr removed per second also -- p V +3600; Bence, v' -- p V+ 3600s. Substituting {ts value for v’ in the aquation, we finally obtain: pA 8(. 268 X 3800) ._H t Pier Vel +at) I4FR. : in the example off page 57, R wae -found -- 20.75 fer a hot air furnace. Assume that this value may be increased to 24.; take the temperature t -- 100% and assume 20 mc. of air to be required per kile of coal, 211 these conditions being unfavor- able to the draught; substitute these values, and we find: Se mpage" = a a HATING AND VENTILATION. phate: 130. . 268 X 3600 X 10 VEL x8, PAS fab Gd Se iy C29 4 ntvar performing the haeiiate b4 one, we find this sensibly equal ems A p=) FOS) VT - fF Section of Hot Air Duets. °--- The yelocity of the hot air the ducts depends on the height of the outlet openings a- ) the top cf the furnace, on the average temperature of ii air, and on the pest avant op offered to the passage of the -Swhen the air is diavironted to several different stories, each of these usually has its Special duct leading from the ‘top Of: the furnace: thts arrangement should be made tf pcossi-. bd 6° for the hot air would otherwise almost entirely pass to ithe upver stories, whose drauzht-height is necessarily much ithe greatar. : e Henes the problem will be separately treated for sach story. Let h -- height ‘of the outlet opening for one of these stcries above the top ef the furnace; the temperature of the smoke hac just been determined. The resistance R is determined in the manner already explained in treating of the flow in ducts, ta- king acecunt of friction, bends, changes of section, etc. These elements being fixed, the valecity of the hot air will be, according to known Pea 2gha(t ~ 15° | (1 + 15 oe Cl FR). the room into which the air passes being at 15! It frequently happens that the air does not freely pass frem this room to the exterior, only escaping through crevices ar- eund the doors and wi ndows. as pe mentioned in treating fire-places; but in this case, i ead ef producing an cbsta- cle to the passage of the atr Dy SGapraaaian’ this ebstacle re- sults from an excess of pressure. The effect is similar, and the velocity of the air is reduced avcut ten per cent. IJlence, in practice, the results of calculaticns must be increased, not diminished. The preceding formula may be simplified. [. It is impossible to transport air for long dis tances without great loss; 20 m. Should be taken as @ maximum. Sines the arranyements are near ly similar for all furnaces, the value of the resistance Ro ly varies hetweenythnevdimi rex3xandxleyxforvexampiavy within very narrow limits. Even if _it varied from 3 to 15, for exam- ple, the value of the term\Vl + 2, in which the resistance en- ters into the formula, would only vary from # 2 to 4. Then in practice, it is usual to assign the value 3 to R, and per- forming the caleulatiohs, to replace the preceding formula by the following. - v.22 O09 \/h(t - 18). (4). After fixing the volume v*, to be distributed to the story eonsidered, the total volume. being V, the section of the spe- eS Can eaters Tp ay et Ne for Vs - lh ” RATING AND. VENTILATION. : ve eed] Pecial duct. ‘for. that story will be &@ 4 my e “he Inverse Problem. --- The inverse problem may be stated as follwes: the furnace being constructed, tts dimensions, heating surface, the sections of the air ‘ducts, the heights o {ts outlet openings, are all known; required the volume cf ai . furnished per hour and its temperature. | Commence by determining the total number of calories which ) the apparatus can furnish. This -- 3000 8, tf S be the area of the heating surface. . | Letting V-- total volume ‘of. atr, and t its temperature, the two aah quantities, 9 being the externa | rT ens we hee 4 22 Vet — 9) -- 300085... This” ig a first. relation between the two unknown quantities. If the hot’ air be distributed to a single story only, the expression for its velocity is; v -- .O8Vh(t - 15), h being the height of the cutlet openings abovie the top of furnace. Tf there. are two stories, the heights being h and h’, the corresponding. velocities will be; . La abn .o2 VA(t - 18), and v; -- .09 Wart = (i8y: a The relations are similar for three stories. Take, for example, the second.case; let s be the section of the duct for the first story, s’, that for the secyond, both ¥Vnown. We should then have; sv+s’v’ -- V, which relation expresses the fact that the sum of. the volumes passing through both ducts equals — total volume. This equation my ve written: .09 \/t - 15 (s¥h+s'\/h’) -- V. (b). ! Bitmiiat tng Vv (ear equations (a) and (b), t becomes known from the. equation » O8\/t = 16 (s\h-+ s'/h =< 3000 GS - bene .312(t - 9) whieH is a numerical equation, to be solved by trial. It is therefore more simple to solve equations (a) and (b) in their original form, substituting several values for t, until ons is. found | to give the same value for V in beth equations. The Se ‘ofi the Craphical Tables hereafter given will greatly faci- Bib this process. PRACTICAL. RSSULTS AND APPLICATIONS. He abhi 6a Tables. --- Tables 38 and 40 are arranged to ab- heey i ate calculations. The first gives the secticn of the flue of the furnace, when its height and the quantity of fuel per hour are known. The second gives the velocity cf the het Bir in a duct, if the height of the outlet opening above the urnace and the temperature of this atr are’ known. The arrangement of these Tables is similar to that of all fadles previously given. The questions just considered hyy hereby be solved by means of a few simple calculatiols. Ci em Ge two). 8 tor | each: containing. Paes oy § rooms 8 x8. m. and 4m high. Fe: paeh story, reg eae exrernet Smnuerie ot ts 148 mes. Tost » gh shinatis,. ls vine Ta thet 20 osha escape J igh the. cr ana ceiling to be 10 tor. aach, story, par hour, ie: i la x 29 - oneeee 70%, Ho 28s 6 610 a ae ae oe é ye iS. ig cee “ABT... vi i r both etories. we oath: assume this tc ound numbers, for safety. : Rey apo, aes out of the rooms ‘Band « The heat 3 -- 11232 oms icon a iw aue. taken from the 5 goslity Mons ‘must. ‘gurnish the heat to raise ar vores oe Ny the ‘furnace mst sup- eg inne he. Nosed yi or Heats pup- gh the uct SE the connie ce equals that escaping a aed a ealories. Then 23.4 V.-- 2123 908 m2. ¢. of hot air Pequired sa ( atred Mists . a ee heating surface, rite pet, smoket Aiea. ete., in eon- | _ tact with the air 21230 4% 3000 -- ¥7.10m. s. tf the furnace - be constructed of ‘cast iron, metallic. ‘furnaces usually furnis / ing an average of 3000 calories per hour per ms, cf eeabeine | > surtace. If the. furnace is of brick or fire clay, the heating surface should be 21230-+700 -- about 30 ms. , 4s such an ap- | Paratus ‘only permits about 700 caleries to ‘pass from smoke to 3 ey wn ome? ata t > fa aaa a A = it "y ’ Ayes ‘ ag } sy eas Nt *, ee PING AND. ‘VENTILATION. a | 133. ey Porm. Be Pee per. hour. — “AS already. stated, themes Pee Cures dimens fens should often be increased in practice, that the ap- . paratus my have hake of power, ine Nee for extreme care He Phe: oe RE 4 2000 -- 1 O71 ms., as re burn per. Thess This shcould. be we as. already” indicated. ~~ | Daag ae Mat oe 39. Assuming ne ‘thie ute parecer 0160 nm. allow for Boot, cfor forcing the Yr, ducte. are aane by Table 40. Assume t story to be 3m., fer the second, + The temperature of the air is 70. seend a vertical through 3 m, to the ZRontal threugh this point gives 1.10 m. én velocity in: the duct for the first ait df duet, 3 velocity of 1.60 m. -is found v laine, lot alr is 908 me. , which may be divided y nequally between the two stories; assume that 600 supp ted to the first, and 408 to the sectcnd, per hoktr st story, 500,4+ 3600 -- .139 me. per hecond: ths "1.19 -- .126 ms. -- tection of duet. For the rf, 406 43600 -- .113 mc. per second; .113 4-1. 60 8. -- the section. re ag to be increased in practice, so that reg- SHIA tke be aR calculations. - Bxeample 2. --- In the preceding wrgise the temperature of the aif was arbitrarily assumed to be 70° [ts volume might be assumed, its temperature then being found. Thus, Tet the volume introduced per hour be 1800 mec., pre cisely equal to the volume escaping; this assumes no other means of Ventilation to exist, other than the forces evacua- ‘tion caused by the introduction of the air. First estimate the temperature of the hot air. The escape of 1200 m. c. of air taken at - B and expelled at 15° carries “off 11230 calories, and the logs through the walls was estima- ‘ted to be 10000 calories, making a total loss of 21230 calor- ies . Y ue A ce % 32 Ean es ae hee. 7 s i Bye pat i _ PRAPING AND YVANTILAT ION, a 134. alories, which is the quantity of heat. to be supplied by the furnace to. the air taken fron. without. ‘lf this air. be warmed igh degrees, we must have 312. X 18600 t!. -- 21230, the first aiaies: representing the quantity of heat "pequired | tc rasie the ppemrare tate. of, fae me. of air t’ degrees, Hones: t! -- 12 24 “since the air is taken at - 5. the temper- ore of ‘the hot air must be 33, cand es vertical. through, ee 1 toa point yeen t e eurves: for 30 and 405 this @3 m story, we ly obtained. | ited to the akin be > at \Leay t a an nd the furnace having It its volume be vk ame 10: it pas of cast anon © As ahbss two i ve ae) Le 2, foo hk Oe ae -- 1960 a he “Table. 40. shows tae ‘for ‘@ hhegpht: ike. ee ‘story, a velocity of about .5© m. corres- s te a temperature of 302 Fot the height of @m. for the cond story, we find a velocity Of. 850m. 2° The flow. through the first duct then -- .35 x .68 ---. 2065 m. Cc. per Shag or 743 mec. per hour. — “That through the see- ond duct (IO 86 =-" S2ER mc. per second, or 918 me. per hour. “The” total - - 1861 mc. instead of 1950, required. _ Make a new trial, assuming a highre temperatures 40, for ex- L) ID VE I TLATPTON, i, A 36. The hea ibted to the volume V; ‘tora. liter en A cuharatere: Of. AE Ons 14,04 X cM Pealories, and V itself hae 21300 -+4-14.04 -- 1520 m.¢.. i a athe: RICONS in the duct. to the first story -- 78, the het “2 8.8 40; that. in the duct for the second is 1.08, Peasowen the first duct -- .36 X .75-- . 2626 me. per second, or 945 me. per hour. That through the second -- ,30 X 1,08 -- 6324 per second or 1186 mc. per hour.» The tot- ; al is 2111 me. instead of 1520 mc., required. The result of the first trial was 289-too small, that of the wicca: B91 too large, nearly twice the former dt fference, The Sih Senne ture ig then about one ‘third the difference of the Ae. greater. than the first, or about 33° which ue, as we know from the second examp |e. he perature as a ‘by Table 40, the velocities a 1b W ee and 292 m7; ‘about 800 me. flow through MOH i. >. through the second. , »* a ne aay neve * shee ee oe et ne ee HEATING AND VENTILATION, pee Ge 0 THe OIE RM Ga mene te | heating apparatuses placed in the rooms to be 7 their fire pots having only sufficiently large to ad- mit air required for combustion. ae "The simplest stoves merely comprise a fire pot containing “the grate and the fule, surmounted by a smoke pipe. The fire pet and the pipe are heated internally by the hot gases of ccm puation, the air of the room being warmed’ by contact with then, This kind of apparatus evidently furnishes a much greater quantity of heat than a fire place, as, instead of heat radta- sd from only one side of the fire, all siées of the fire pot are in contact with the air to be warmed; sven the smoke pipe “aids in the warming. Besides, the quantity of air removed is much less than in the fire place, the epening being quite small, so that a much smaller quantity ef heat escapes artd is lest. But, for the same reason, it is. much less healthy than warming by a fire place. Also, great differences of tempera- tura exist in the room, this being low in the lower part of the room and quite high near the ceiling, where the air accu- mulates and remains stationary. These are the principa!l advan tages and disadvantages of the otdinary stoves. ‘In the case cf more perfect stoves, the fire pot is surroun- ded by a casing, the air circulating bewween them, and enter- ing the room after being warmed. These stoves are really het gir furnaces, and in general, all the arrangements indicated for them are applicable to these as walt. | Computation of Dimensions. --- To datermins the dimensiones of the different parts of 4 etorve, procesd in exactly the same mannsr as for a furnace, this not requiring repetition. ' Example 1. A Stove without Casing. --- A stove is required to heat one of the four roons considered under Furnaces; this | room being @ X 8m. and 4 m high, with 73 ms. of exposed external walle and 15 ms. of glass in windows. As already computed on page /3Z, 2135 caloriss are lost through the walls, -but we will assume 2500 calories per hour. “We will also assume that, the air is changed twice per hour through crevices around doors and windows, and by opening the doors. Assuming the external air to be at - 5, and the tnter- nal air to be at 15° the air is to be warmed 20°. The heat carried off by 2X @X8 X 4 -- 364 me. of air per hour -- .312 X 384 X*20 -- 2400 calories. - he total quantity of heat required is then 4900 caloriss. The heating surfahe -- 4900 + 3000 -- 1,65 ms., which must be taken as a minimum, as for furnaces. The quintity of fuel -- 4900- 5000 -- 1 kilo ef coal or “coke, of -- 4900 +- 2000 -- 2.5 kiles ef wood. | . HEATING AND VENTILATION. | ees. rate aurface BAe 60 + 60 -- -O17 ‘ms. for ecke or cocoa} But. a es Ti. 8 40f hee ad. Aabintng, hak. the external surface a oan the ptpe must havea surface of 4 Teng th ip Set? room fog a ae {ts dame teriig ieee ne hese, as the ca- bsaaatol fire pot and pipes, --~- The i ineem of ly: corre aaponding diameter of .08 a | 12 m., to allow for obstruction by : : oh oy final temperature, to heat 3£0 me. he "312 X 320 t' -- 118 +? ealories are required. ‘This quantity of heat must also. compensate for that lIggt through the walls, ete., and that lest in the air escaping at 15: hence, 118 t' “4 = - 4900, whence eh ie “A900 4-118 -- 41, which is the. differ- i ence between the initial and final temperatures, seo that the "S2 actual Ns atl ng auld of the hot air is then 36. fad Fi ae? 5 ra 9% $ Ss Boat = 4 “BRAT ING AND VENTILATION. Tts vebentty is easily found by Table 40. -Assume the ei inght -height . of the outlet above the inlet to ‘be 1. 20 m. this: Table then | gives a velocity of about .45 m. for a temper- ature of. 3606 But, the length of the air passage being short and its section large, the resistance is much less than for 3 ducts” cf a furnace. Fence the velocity may be increased ope, halt without error, or to .60 n. gection of the air passage between the stcve and its ca hen be at least 320 ++ (3600 X .60) -- .18 ms.,% fair being 380 + 3600 mc. per gecond. - t the. same apparatus warm the same room as le, but the temperature of the hot air. n f the conditton that the volume of air pplie yy » stove must. be giant to that escaping from the Ih oom. fn ‘the ‘same time. — K, the escaping volume. is fixed by bie Bann bean that the air {s to be renewed twice per hour. The quantity cf heat lost per hour ts 4900 calories, as before. | The heating surface, quantity of fuel, grate surface, and section of the flue, all a tiees as. ‘before. ¥newing the temperature of the hot air, which is 70, and SS oe hetght of the inlet avove the outlet cpenings, 1.20 m., th relocity. cah be found by Table 40. It. is .70 by the mia, but we will increase this to .ff m as before. | Let V -- volume of het air passing through the apparatus per hour, this being taken at -5 and escaving into the room at 70s hag received .3123 X 75 V -- @axaxeaieritesg23.4 V caicries, which must -- 4900. a i hence V -- 4 00 +; 23. 4 -- 210 mec per hour, or 210 # 3800 -- .O5f3 mc. per sécond. The minimum section of the air passage must then be .05&3—- He -95, according to the velecity found. | The stove introduces only 210 mc. per hour, while 380 must escape from it undér the given Nonditione, so that the differ- ence of 170 mist be furnished by the natural ventilation of the room, The efficiency cf stoves varies from 85 to 95° per cent, an average of the best kinds. i “> 25 fy 5 "2 Fs ae Lis “EATING AND VENTILATION. ; ea 130. oo EATING a ST ene Te | : | LL eae In all ‘the systems a ALS Rombie tient) tn the: ye. con ea a pee eae hereafter hata. empleyed as an _ intermediary, eas the heat frem 5 of osetel Wricce™! hea whi ch the Prasat ate. Thie a the gam stma.-! | ‘tte ahaa tng. point, each ki- 160), calories. | adi aeseratur, we whe assume that 600 calories are giv- 1 up by a kilo of stéam in condensing. Hence M+ 500. Kilos -- quantity of steam required per hour. Ths: weight ‘of the condensed warer As equal to that of the ea, from whieh AD as formed. | 3 . e~ | fer 10.33 m.; the temperature of 150° cube} 47 atmospheres, or néearle 49. m, Gea a f Incipal elements, of Dotlers, ney, according is to. be heated, wik ty oF Went: peas ready is calories per hall. A For 900 calories condensing surface mute == 3000 + 800 -- 3. 26 1 quantity. of steam Peccl ree ber hour -- 90000! 500 os, or 6 kilos per radiator. ions of the boiler are found by Table 42. The t Steam being 180 kilos, the boiler will be © herse ‘the heating surface will be from 12 to 13 ma. : about 8 eos cf cecal must be burned ver hour, and the grate surf- jace should be .37 or .38 ms. The. section of the @kimney flue is found by Table 43. 30 Et les: of ecal being burned per hour, assuming the height of 2 flue to be 16m, tts section should: be .09 to ..10 me If weed were burned, whe quantity required per hour would be to that found for coal in the ratio of thet calorific pewers of the two fuels, or as 5 to 2; about #4 75 kilos of wocd. ‘The section of the chimney must then be one-half larger than ‘for coal, or about .14 or .15 ma. Diameters of Steam Pipes. --= Bach radiator receives 8 ki- los Of steam per hour. If the pressure in the radtator » Wh whteh should always be low, does not exceed 1 1/4 atmospheres, Table 41 shows that 1 kilo (Of steam , on entering the radiatcr has a volume of 1.38 me., the volume of 6 kilos being &. 28 me The supply pipe must then pass 8.28 mc. per hour or .0023 mM.C. per secend. To avoid noises, and the return of the Steam it must enter the Yadiator with a very small velocity, about I to 1.20 m The section of the supply pipe must then -- - 023 + 1, 20 -- about .002 ms. Its diameter should then be b centimetres, " MEAPING AND VENTILATION. _ 145. Yy pipe from the bohler,: which supplies all the ss 180. kilos of stéeam-per hour, or .O5O ki- this part of the piep,: the steam is under a F Uusraa that of- (11/4 atmospheres in must: overcome the resistanées of Seat aN be ore reach fing the SSX 8 Mv eavioig Witeh gives 2¢ eharge can always be ain oo. pipe | the ae Be fy branch mipes receiv be eonsiderably re- it Bost be reduce that it , greater in Sie’ upper story, and the eed: vhere. : eanchiwonid’ pass. more. than the second, the third, with equa? sections. --- If the radiators contain water ting surface of each radiator, inter- ae 3000 ~- 700 = 4, 30 mm Ss. | E ‘Tts. diameter depends. on its be Psighe | ee radiator. -If its length is 1.5 nm, tts ale should be .0@4 m.; if the length is 2m., the - diameter required is only . O48. m. Nearly the same section UO elle Le porter to the return pipe in the radiator. ) SERARING AND. VENTILATION. f’ 148 | HEATING BY HoT WATER. LOW PRESSURE, Shae “THRORETICAL FORMULAE. | : nciples of this Mode of. bien) Shige A botler c C, comp = SRE AAE pan fa eed eoage amare: cellar of the atin . The entire circulation is “filled with water, as well as the boiler. The water fs heated in the boiler, expands, and from its di- Minished den sity, rises ~ tn the verti cal tube to the expan- gion chamber where it is — permitted te expand: it ee ge oa ee hen descend h the See apparatuses By ‘Py ‘placed in the ac, 6€- 57 ee ~~~ K00 =e HH E> ... of Heat.’ --- The quantity of heat required is de- we have ‘repeatedly ae lebpe especially in treat- fun - Several examples J ale ans: Ply menue no pepetition here. We wil] as 2 calculations to have been mde, and that M is the number of ealories to be furnished | per hour, — Heating Su rface. -- - According to experiment, hot water transmits | to the. surrounding air, | per. ms. of heating surface, ee of heat Th cae | 360 to 00 or 700 calories per Seca, | eu oe Fete ee oe ei Fae + { Sex rank tae orate ae PALE. iO BRAEL an lev «beget & Cn lial VYRATING "AND VENTELATION. ; S137, hour, according to the temperature of the water, at 60. ‘or 90. The water is at 930 on leaving the boiler and while ascending the vertical pipe. If the first radiators are quite near the .botler, the temperature of the water is then about 90: but it is cooler in the more distant apparatuss, it usually returns te the boiler at a temperature of anly 30° Hence, it ts best to take 60 as the average. temperature of the hot water, and to assume. 400 or 500. calorées as the maximum quantity of heat | 6 Per hour. and per m.s. of ene Seeds surface, un- nie “a | omhis surface me eraluer large. nti . D ere Let t -- tenper-_ 2 ire of the water. on entering the. radiators, t’, its tempera- ture on leaving them; the sepeific heat of water being 1. as fing “from t to. t', each me. then yields 1000(t - t’) calo- ries; as we. haye- just seen, t usually -- 90 and t’ -- 30; Gio, tyes @0, which corresponds to 60000 calories per m. ¢. But this Ag. net ‘all utilized tn heating; let us assume, for example, 60000 calories per mc. Then M +-50000 m.c. of water MS b_ circulate per hour to yield the M ealories required, or L “3600 of this quantity per second. “Velocity of Circulation of the Water. --- The circulation of the water is due to the difference of weight of the denser eolumn of water, cooled in the heating apparatus, and the hot- ter and lighter coldmn cf water ascending from the boiler. ‘Let d -- density of the hotter water, at 90, for examble, ad And d’ the density of the colder water, at 30. The average density in. the descending circulation -- (d#d') +2. The ifference of pressure of the two Ae lel or the motive pres- sure, for a height he (d' - d) expressing this difference 2 a’ in a aaah of water of the density ad’. From the formulae for the flow of fluids, which are rsarefut- equally applicable to liquids as well as ases, the theoreti - al velocity will be; VV. ~"\j2 e bid Ce aaa 2.0 _ The densities d and d’ are easily found, when the tempera- ures of the water are known. The density of water at a temp- perature t is nearly -- 1.0086 ~ 0. 0005 3. or Lag ne the calculations for the erdinary temperatures of and 30, we easily find V -- 0.843 Vh. Diameter of the Main Pips. --- This is the theoretical ve- pocity, but it is considerably reduced by the friction in the pipes, etc., as for gases, and this reduction depends on the hiameter and length of the pipss. The diameter is then to be stermined, so that the product of the reduced velocity by the _ HEATING AND VENTILATION. Bs OY. Goa sectional ‘area, 1. e., the flow per second, shall equal the quantity of water previous by found to be Metesaary. _. Commence by ‘estimating the reduction of this velocity. Let d -- diameter of a pips, j -- the ratio between the vertical height. h’ between the ends of the pipe, to the length L of the Pipe; v -- the actual velocity of flew, and b -- a numerical! coefficient obtained by experiment: the following relation bet reel: these elements may then be written: d j-- b ve C2) 53 axx 64 This accords with the results of the numerous experiments made by Darey, which also show that b my be represented by 0 -- 0. 000507 4 0. 000013 + d. (2). pe se. for fj its value Atk he in equation (1), we hare” vey | y Bt gd b L. ea eee eee ecu b L. ae ae ie ee 8.858 VLb Wiloh’ g ad the value of 9. BOBS. | ~The diameter of the pipe is obtained by a lV eatc ities method. Aoaane a diameter d: the length L of the pipe being known, then determine the value of b corresponding to the diameter a. by means cf formula (2); this value ts ‘intreduced in formula (3), also substituting the value of L; the coefficient of re- dv ection A-is then found: le actual velocity v -- AV is then obtained, t V being wey gh’. The height h’ of the cireula- tion is taken from the ue to the head of the upper distrib ne pipe. ( From the lower end cf return to upper end cf sup- pEY) This velecity v betng fcund, the cerresponding flew TEBAT is” then ‘comput ed: this must be compared with the volumeo of Water required, which ts M+ (50000 X 3600); if smaller, the diameter is not sufficient and must be increased; if greater, its diameter must be diminished. ; , PRACTICAL RESULTS AND APPLICATIONS. - Craphical Tables. --- These computations are quite labor- ious; to simplify them, we have arranged the Graphical Table 44, which gives the theoretical velocity V for the hetght h of the eclumn of water, and Table 48, which gives the ccef ficient of reduction A of the velocity, according to the diameter, anc ithe ratio Ld of the total length of the circulation to that Gtameter. a Example 1. --- A building of three stories is heated by 4. Padiators on each story; each story is supplied by a separate pipe. The height ts 20 m, and the tota!t length of the cireu- ‘ ‘ re ~ i i: ; bicrey oon oe Bs Oy ented tobe e Web ey is ‘9 ral fee Piped OES 3 es a hye vee tf HEATING AND VENTILATION. lation is 160 mWe We will first determine the quantity of heat required, fol - lowing the method indicated for hot air furnaces; supposé that 2560 m.¢. of air is required per hour for each story, half this being introduced through hot water radiators, and half entering through the crevices around the doors and windows, or through special inlets, this excess of admission of air result ing from the arrangement of spectal flues for ventilation. The external temperature being = 5, for example, and, the in- ternal temperature 15, the discharged air is heated 20. “Whese average figures may be exceeded in very cold weather. The quantity of heat carried off in the discharged air per hour its then sensibly -- 2560 X .3123 X 20 -- 16800 calories. To this must be added the heat lost through the walls, which we wil! assume to 0@ 4000 calories. Then 20000 caleries are to be fur nished per hour for each story, »y four radiators, or 5.55 cea- lories per gecend. : The heating surface of one radiator, comprising both its ex- ternal surface, which directly warms the air of the recom, as well as the internal surface of the tubes, through which the fresh air circulates, consequently -- 20000 + (4 X 400) ms. -- about 13 ms. per radiator. The quantity of water required to pdsse*throuch per second -- 5. 55 4 50000 -- .O000111 mec., since 1 mc. gives out 50000 ca- lories in cooling from $0 to 30. ‘The theoretical velocity is directly given by Table 44. As- tend a vertical through 20 m. to the curve, which gives about 2,40 m on the vertical scale. The ccefficient cf reduction is found by Table 45. First as sume a d@ameter of .04 m: the ratio Led -- 150-+.04 -- 3755. Ascend a vertical through this value to the curve for a diameter of .0O4m., which gives about .08 on the vertical seale, the coefficient of reduction, by which the thecretica! velocity must be multiplied, to obtain the actual velocity. The actual velocity will then be .06 X 2.40 -- 0.144 m. The section cerresponding to a diameter of .04 m. is .O00176 m6.; the flow ts .00126 X .144 -- .OO017@€ me., which is slightly larger than the iy abe low of .OO0111 me. Try a diameter of .035 The ratio L+ed -- 5000, the co- efficésnt of reduction is oe ~O05, the actual velocity is ~O5 A 2.40 -- .120 m The area of section dveing .O00707 ms., the flow is .O00707 X .120--- - 000085, whieh is toc small. The diameter then lies between .035 and .O4 m,_ But, count of deposits, changes of section, bends, etc., ehculd be at least .04 m. Dimensions of the Boiler. --- Commence by determining the quantity of coal per hour,. For the three stories, 60000 calo- ot As “HRATING ‘AND VENT [LAT ION. ey YE5O, hea lori as are ‘required per hour; hence, 80000 -¢- 3000 ~- 20 ki- los of cecal. are to be burned per Houre 6 . The dimensions of the chimney are to be found by Pable 43, already used ‘for heating by ptean. AN its héight be 2m, & for Rilo tate ‘burning 20. kilos. of coal. ‘per yaa a section of abe ‘ mS. is required. enh a7 eee 3 Ss of, the boiler. Sheela tot be less than , sines we. ee ‘each th. s. to trans \ “™he “iis of aeieelae aneing with the: fact that the bot! 20 kilos of coal per ‘hour; | follow a horizontal ‘Aibhenta: line giving the weeny of cecal; pags | and coer to. that eiving ‘the: heating "vefore, «28 m. 8. for the grate, and am or Water Radiators. x. L. story t re 2560 mc. of air per . trecaly, Saeroadced: ‘by the ventilating | half akg through the Tadiators. Then 1280 € . We clea! found : a VeGnisee of 13 ms. to ee the 5000 ) calories to be eupeh ies by ihae ile: ey dette ‘through ike ‘Yadiator recat - | ere 3000 ) calories. ‘The 320 me. of air will then ee ae A ‘be 2 (ie for example, (this is the height ‘taken from the inlet duct of the cold air to the outlet hot air epenings of the radiators) by means of the two ele- ments, height and temperature, we can determine the velocity or dranght. | nt Soa Se serene oF hie HEATING AND VENTILATION. Ye 151. a Cm ane emoloy Table 40 for this purpose. Ascend a vertical. through 2m., to the curve mrked 30, corresponding to the 1 as perature just founds; a horizontal through. this gives about . 46 . on the vertical! seala, the rejutred velocity of the air. As 320 mc. are to enter per hour or .090 mc. per second, the section of the air duct through the radiator must be . 090 : =. 45 -- .20 mS. The number and section of the internal pipes must next be so determined as to obtain a total section of about .20 ms. and a total heating surface of 7.8 ms., previously aasumed. pipes of .20 m. diameter would do this, assuming the heteht of the radiator to be 1.70.m. Table 40 assumes the air to pass previously pass through a long duct, and therefore gives a maximum for the sections. oe EY the length of the inlet air ducts do not excead 10 or 12 a. , their sections may be reduced one third. ‘ If a great quantity of air is assumed to pass through these radlators, its temverature will be but slightly elevated; the quantity of heat furnished by the radiator wil} practically be the same in equal times; so that a greater quantity of air re- eiving the same quantity of heat, its temperature is inereasé beget The same would be true if the internal tubes were smal- ler. In an extreme case, it might occur that this temperature is hae than 15, the temperature ef the room The external envekope of the radiator would then not only have to warm thé Bir admitted through the crevices of the doors and windows, bt but also to raise the temperaaure of the air introduced throuk th rough the radiators to the general temperature of 15. .In case the radiator contains water, heated by steam, as in the, systems previously described, the water would be at about 105 instead of an average of B04 as in radiators heated by het rater, The transmission of heat per ms. would then be nearly louvled; consequently, for the same volume of 320 mec. cf air passing through the BPParatMs the mean temperature would be bout Be : lt should be remembered that, in heating by steam, fer the ame reason, the total heating surddce would be half that re- uired for Beating by a circulation of how water, because of hese differences in transmission. If, instead of radiators directly warming the air in the oom, how water radiators were used for warming air, transpor- ed through ducts to the rooms, the draught of air in these adiators and the sections of the air ducts are computed in tk he same manner, exagtly similar to that given for hot air urnaces, the only difference betng in the number representing he heat transmitted per ms. of the heating surface, which is Ae Vv a5 ane as a ny > |S HEATING AND VENTILATION. | 162. Breas. for heating int hot wa tor and steam, than for warming Dy hot. air. ae ‘ : Example o. es The same rooms are to be wammed as in the last case, adppting an. arrangement similar. to No 6,.shown on Api abe of ae ia a Bpectst. etreulation for each sto- or che. une must. ‘then: convey 1000 ‘per Sodand. ‘the quantity of water persecond -- . 000084 mc.; each mc. OF water cooled from zg 50000 calories. 11. remaining 20°m 7 mab iel Ag gives a theoreti- -40 m. as. ‘before. The length of the circuls- ins the new AAS cane coefficient of reduc- OA pacto: es a: -- i100 4 04. -- e333: | velocity to ‘be .0625 X 2.40 -- .15 m., Sw to be .OO00707 X. 1s. -O00106 m.c. So that, un- j arrangement, the diameter of .03 m. will be more ent, since the flow. is’ only required to be .000084 Take 20 m for. safety. eee i 18 Seca (eetuas the ) diameter of Sach main pipe. In § ee ee ‘the pect lon ok thie pipe must then de> t of one ascending pips. this, | the main abate! feeds but 3 i YE pipes, ea thought ‘proper, Hie ee pes; Expansion Chamber, ---. The eopanaiay: pipes : generally of wrought iron, which ts used for the distribu- ting: Pipes, which are also sometimes of copper. As for steam | pipes, “tt is. mecessary to provide for the effects of expansion, by arranging a sufficient number of bends, ete.; it is also necessary to cover them with non- -conducting miterial. The in- “ elination of the pipes must alsc be arranged so that the air enelosed in the pipes or sst free from the water, may return to the expansion chamber. When high points eannct be avoided, Pere this air sp aati traps. mus & be provided as for “Steam pipes. f The expans icn chambers are const anaes of plate cr steer {- ata TO ae Us: eis ee ee a hers icerwiy aL Ste aees Bers eeingee. at 1 Lar he 5 ioe poi nalagewsh PALE OF a tualibd gate . f : ; ; are 4 be 7 33 Skt oS ant tent, npkehadae k ion: ie at yedsg oF hha? gets es obts loam £ énrev inolane pot aioe! 9 bests as raga T6.gH0i! . pte. 10. Ye2 aeetp tpang ae Phas ‘Bool sl vy. i at MALES o DieH. 64% ‘sede rood 5 tw & | oat PAO OT IT OF: sah 1o¢ sd Moth neon? £4; He es iy tro } o5 > POT “OR bt oe ne ont} a ede mt Ra Sa | |. HEATING AND VENT [ LATION. BS. Tron, their. Pe euneity being suffictent to receive the excess cf vetume: Peeulting from heating the water: the variation cf vel- | vi 20 the total volume; | ‘the c2pacity cr the ex- reek gh chantier should exceed this amount, so that no portion FS aie 1e ir ma A trap must be placed tn the he acape or ‘the: ‘air or steam, and it must be lightly Seiad he main and the distributing pipes are 0 the bottom ef this chamber, and each should be fur stopecek, easily turned from the extericr. must also be provided for adding a quantity of water, m tt > to time, to compensate for that lest by evaporation. 18 Ripon ray ve | aeeaues oe several ways, which are not eq- oy eee ‘The arrangement No 1! te PANG a eee worst, because it. ie. does not. ansure a gocd pgistribution ef equally het water to each of the different stories. In the second arrange - si} ment, a special pipe ex- AW tends from the betler to the expansicn vessel V, ahh ee ges from which a Single vipe / che! adprapent Stories. This has the in- t the water is cooler in reaching the lower . . the ae ie is not uniform in the different peumd each story is suppl ted by a sepa- “he Giocrteat thing is that each story A g separate supply; the return pipes may be com- bined, unless there bea gréat difference. in the number or the “surface. of the heating ap Ipartuses on the different stories, as . the. water might leave the different stories at temperatures materially BLE Repent, 80 as to cause ait itt. in a single - return pipe. tn When the supply pee es tel directty from the boilers, the mode of connect ing the branch to the expansion vessel is of sone importance. In that case, it is not necessary that the ter. contained in the. expansion vessel should be at a high temperature, since it no longer supplies the circulating pipes his. would also. ‘cause the loss of a great quantity of water | and Heat Oy. exaporation, without benefit. Henee, system 4, Which takes” the warmest. water from the boiler to fill the ex - | pansion chamber. directly, is Net so good as 6, which enly ta- of . * ae 3 b 0 A A on 5, a Bite. second. method of supplying the radiators has the following. advan tages; the. hot water passes directly te the tory. to be warmed; in eh first system, it aseends to the expan- sion vessel, then des-, noe eending to. the atory tc - be warmed. -of heat. i: greater lossthe distane aos Movs cyenie for aa huis geparis’ me emed 1 alae forceontat ty. tocneshe eter: it has pe air of smal ler dimeter, i eos. ney etbor and is stopped escaping Sibae the rocm at A, ah bac aban i I a “HRATING AND VENTILATION, team BY HOT WATER. EICH PRESSURES. iples and Ceneral Arrangement. --- The principles of Ba, this mode cf heaing invented by Perkins, are exactly. Similar te th for low pressures, but it is much mere simple. | The entire syetem consists of a cs a single circuit, composed’ of a very small pipe, . O15 m ‘in internal, 2 WORT Th. external ‘diameter. [ts ee ekdienc of .006 m enadles it to resist pressures of more. than 200 atmospheres. There is no boiler; spiral coil of the vipe is placed a furnace and dire@&ly heated. Th ascending pipe is connected with a ereer pipe D, tightly etosed by a cap ‘at its upper end, which servés @s an expansion. chamber. A tupe © serves. for fihling the pipe. - The ne ca) ct ine e g deconatna tube C circulates arcundc pepe a ares to be heated, being ar ranged ina spiral form, where muc o eat is to be given out. The tube _F, with its stopcock, serves for emptying | the system. Arrangement of the Sota --- Ks the apparatus is subject to h | “the: ‘joints must be very strong atid perfectly. 8 effected Dy cutting. right and left threads in pling, which is then screwed up @o as to jam the ; one hia into the flav end aS the other. The =e: ‘The a ihe is. ‘ftrat. Tillea with water, using a force eee ean produce a pressure of 200 atmospheres, a8 te test the pipes. The eoil A is then heated, raising pemperature of the water to 180 or r more; the circulation is. produced as under low pressure; the water cools in the rooms to be, warned , and returns to the coil at a temperature a about 60. “Hence, the average temperature is about 100 to a lese temperature of the water in the coil. It may.be varied The velocity of Fe ee is determined by the greater or within @istant limits; at ko 180, the pressure hardly exceeds 6 atmospheres; at 200, the pressure is 15 atmospheres, and the apparatus is tested to 200 atmospheres. fe & 2 iy : ee eared LS Si 3 HRATING: “AND VENTILATION, = THe. _Ageording to the experiments of MM. . Candillct, 30 ‘Titres we wer in a tube 150 m, long will heat BOO'm.c. of air. . pod @ spiral coil should have about 1/@ the total. length of the tube. The Paves te of the expansion chamber should be a | about J} -/3 the total volume of the wat - employed, or of the internal capacity o the iesss/ . The furnace is quite small, and can bo placed even in the occuptad roons: to “warm 500 m.c., the furnace should be 1.1! tT. long, .80 m. wide, and 1}. m high. The heat ing pipes are generally placec below the base and covered by a slight grating. 800 or $00 calories are trans- mitted per ms. of heating surface. This system is very simple and econom ical, but is usually considered dangeroi from. the high pressures to which the waté is subjected, though experiments appear to prove that this is exaggerated. ty s 4 “is e lbh a Viti sii HERO yea ‘i D iticninciine. Goa.) oe The combustion. of 1 ki- ehas 10000 © eajlories, forming LK 10! Gries, ¢. rae round numbers. — Tt likewise produces 2 of water vapor. i ies ete whose cape weight is 0.68 kilo, can Of: air 20, if its heat is Ne see This Lie into the at- to estimate the quar 3 loss” ‘through the da “pemoved, with the ividing. the total ad by the combustion | ‘ © that the products tor Aaa carseat fa found as sual for. ‘the water vapor, ast eondition requires from shed, according to its tem- ond Dts ieee woegealie: for warming by nate “a pee Lees calories to be eure , 0081 france. - 0203. . O5€1. ( tail i, oo ak 7 ea , a ne ae Toe re ser ts hati HEATING ‘AND VENT LATION. tae ik BB, - “COMPARISON OF DIFFERENT SYSTEMS OF HEAT ING. order. to compare the different modes of heating in actual , they must first be considered from several! potnts of bes “the economy in first cost, in supervision, and in maintenance ‘ventilating power: ‘uniformity of temperature in the rooms oe “ F SiR ea a in ie il yd and the ae ania of quickly and apparatus, eee the preguess of Roma e bi ca 8s- toom; it is the mest economical, since all the beda remains in the room; {it is also the most un- r “Hence,” ‘these forms of apparatus can Roni tn Case: @ powerful natural ventilation is estab- lo of carbon, when completely: burned, ifuedt shes "6000 Re that antes ef heat is Buen atant to fasise the ek iperat re. ‘ef 1000 mc. Of air 25°. The products of cembustion eontain nearly 2 mc. of carbonic acid; if 1000. mc. of air can be introduced, the proportion is only 1 “6000 and will dc Braziers can only use a special fuel. Cas stoves or fire- places employ a costly fuel, which has one great advantage, that it: costs nothing except when its use is required; the warming begins and ends instantly. If the heating is to be in termittent, the room only being warmed for a short time, the use of gas my be advantageous, in spite of its high cost; it requires no superviséén or mintenance, which my recoramend warming by gas under special circumstances. It ois: absolutely necessary to avoid all ae ge of carb - onic oxide, resulting from imperfect combustion, for this gas is a deadly poison. The result is obtained with difficulty; one per cent of carbonic oxide in air is sufficient to kill animals. This is the reason that a large supply of air is re- qilred te ensure the combustion of the fuel, and aleo to re- move the potsonous gas, which my be produced. | This ineonrenience is not to be feared in the ease of gas, but it is avotded with very great difficulty, when charcoal! ft: ‘burned. . Carbonic acid is muchl less dangerous than carbonic oxide. Fire-Pbaces. --- Warming by means of fire-places is any- thing byt economical; their smalle efficiency has been shown, ev3n with the use of the perfected apparatus now employed; but this, with the use of stoves, constitutes the sole method of heating possible for private apartments, unless the buildings gee ee ty we ir 4 € Pt caae Utes & At ® Ls. - HRATING AND VENTILATION: : 59: are on a abalw sufficient to justify. cae use of hot air’ furne- es; if each tenant, in a single building, desires. to ‘Wary the eating at. pleasure, independently of his: heighbors. SAR ARR x reasing tendency | is. manifested ER America. to arrang -@ common system of heating for an entire duilding, and. even fe) — on- tire quatrer of a city. | ie oe ntage of. the. fire-place is. that the fire te. g 2YS- pleasant, and that the ventiJation is ss of mest ania te” vaven she cause of tk Paes torants the : cont al- ee the doors prizontally. along. the floor, . part of theo openings, . -place, also. in the lower | two. CAUSES, the Lanpera tuts at at thet. ceiling. i ings at. @ certain. hetght, admit ibe hang a AS lat placed in tk in con- ti Sara lyoutain ion, eae reduces the » ie the xreegm lower part of the room. t n fire-places, which supply a much grea admit this a£r warmair at the height would naterally tend: to. remain, fron . these forms of. ‘apparatus: aregable ‘ef suffictently uniform at diffePent | air furnished by them is nearly suf Pout 3 she draught of the chimney. Then there is scarcely’ any ce of air through the dtentees of the doors and windows; the’ air mus t descend to reach the opening of the Bt OP a aear ‘the temperature is equalized. We have also stated that, since the air reaches the chimney at an elevated. temperature, the draught its thereby impreved. The ordinary fire- ‘place is. only sufftetent for warming sm] Drsome. cike bed rooms, as only the radian heat is utilized. With. Fondet''s apparatus, it is possible to warm a room cf con yeideradly greater. ‘eapacity; the rooms of. barracks may be warm ed by the: Calton. fire- places. In- arranging the last, it is ! | HEATING AND: VENTILATION. 160. best not to admit the warm air through openings in the same the air would descend too di- [t pata ~ It ts equal te the height of the the supplyo of air can net aces, where this height is that of ons or mere ‘stories. 5 Stoves are then unsuitable for rooms ecentaining a large numbe of versons, or of invalids, where a powerful ventilation, is © quired, unless.this is obtained by other means. Under ordina ry conditions, they are perfectly adapted to rooms of ordinar size, occupied by seyeral persons, cr for a few hours, like dining rooms. When a draught cf air is established through the stove, tn question may arise, why the air enters the room, and how a quantity eseapes, equalt to that introduced. It. partly escap through the firep pot, as in case of stoves without any enclo sing casing, partly through the crevices around the doors anc windows, or through orifices specially prepared for the esca; cf the foul air. Contaary to waht occurs in fire-placess, there must be a slight excess of pressure in the rooms to force the air outwards. This excess of pressure must be fup- rea yy i ae Hy i @ HEATING AND VENTILATION. 161.. supplied by the warm air, and as the draught-height for hot air stoves is so small, the establishment of this excess of pressure within the room tends to diminish the draught. Hence one should not count too much on ventilation by means of this apparatus. The fire is very easily managed, especially in case of a continuous feed. The facility of regulating thed draught by ‘dampers or registers gives to stoves a certain variability of action, which makes them quite economical. Stoves paciate but léttle heat, as the fire is net usualy visible; the oppesits walls are hot then heated as with fire places. The air of the room ig here warmed by contact with the exterior, ascending rapidly towards the ceilin The hot air usually enters horizontally, which mikexxwixk mixes the air better, than if it escaped vertically, and theh ascedded xexzisaiitz. less directly. The draught of the fire removes a portion of | hat air near the floor: .Still, there is a great difference ‘between the temperatures bree she. floor and 3m ab- ove 1%, sometimes ae to 14° for ordinary, and 8° for ventilating stoves. ‘tot Air Furnaces. ---+ Fire -places and atoves are generally insufficient for an extensive system of heating, and reccurse must be had to the other modes of heating previously descrivec Hot air furnaces are mest econcmical in firs’ ecst; the sole heating surface is that of the furnace itself; "the air is ther. ,transported directly where required. In heating by steam or hot water, @ primary apparatus or boiler is required for heat- ing the water or steam, and then a secondary BPpere tue, where she heat is emitted, whieh. has been received. Furnaces are also constructed of cast ircn, which ig not expensive. But the warm air cannot be transported to any considerable distance without serious losses;, gsesulting from the large — dimensions required for warm Ry ey ducts; these lossés easily amount to 25 per cent of the total heat, and may even attain 5O per cent in rather long PID PE Hence, hot air should not be carried more than 25 nm. In extensive systens, where numerous wings are to be warmed, which are distant from each other, the number of furnaces mus be increased, which takes their first ccs} great, and, their care still more so. A tn directly heating the air, the temperature of the cast ir froh surfaces of the fire poet is entirely unlimited; if a part of the distributing registers are shut, sc_as tor restrict the circulation cf the air without reducing the fire, the heat pre duced ig not removed by a sufficiently strong current of air, and the cast iron becomes rec hot. The air becomes heated, at and the heating is as unhealthy as possible. The possibility ok HEATING AND VENTILATION, ee 2: ef a fire Increases; the wood-work Néar the hot air ducts be- Comes very dry, easily taking fire. For this reason, furnacer are never used for libraries, museums, record offices, ete. The use of projecting wings cr flanges is a great improve- 1 Ment, beacuse this inereases the surface in eontact with the/ air, and the transmission of heat. Still, a current of air 13 pequired, sufficient to carry away the heat produced: this 3 independent of the Nature of the heating surface, and res -~- ults from the section cf the air duets and cf the ownlet for the warm air. Ifa Dart of the registers are closed withcut iminishing the ffre, the ribbed surfaces would become red het as wall as a flat surface. ) It:ts true that a Part of the heat >vassing threugh the trans aitting surfaces Ys radiated into the brick walls enclosing the furnace, and forming tts hot air chamber, but the greater Portion of this heat returns to the air. The use ef bro} ec - tiona is not an abselute protection against accident. Pheir rela advantages are shown under normal conditions; t neat passesm more rapidly, sinee a nore extensive surface j presented to it, the temperatures cof the cast iron fire por eid also of the air are lower; still, the fire pot yields a larger’ suantity of heat. Without sensibly increasing the s ef the apparatus, the true preblem cf obtaining proper heat tay be S0lved, which ig to ‘PansPort the required quantity o heat by means of a large 4m volume of air, whose tenperatur ehould net ve very high. ; ie SO BATt this presupposes a sufficient discharge of air, and t} in addition to a properly arranged furnace, well provortione Supply and distributing ducts are mecessary; lf one adopts Small sections, the insufficient flow of air canner carry w away inom the fire pot the heat recetyed from the fire, anc this eventually becomes red hot; which causes a detertoratior of the apparatus, the passage of carbonic oxide through the ped hot metal, te probabil¢ty of fire, ete. Ft if very easy to take care of hot air furnaces | aspecial when the feed is continuous! This advantage, with the economy im fipst cost, has caused the almost general use of this anvvar wine, venen the air is not to de transported for a considerable Gistunes. Tenee, the hot air furnace scarcely has any rival for, warming Nouses. Like thé @tove, i: is wel} adapted to variation i eity cf heating, between timits suffieientyy distan {a n the inter t for prac- jUlcal neads, Nothing is Cagier, than te modify the combustior Dy Opening or wartially eicsing the chimney damper, the ash- PIL AGO peioet¢. et th the sane area Of grate and a sui i chimney. the apatite y eft fuel used May at least be dc Led Te PAT RR AE » — PR) ch a } a a ct en TG HEATING AND VENTILATION. As for the renewal of.the air hy means of furnaces, we | already noted, that the height cf theh hot airduct usually being several metres, the draught is usually much stronger % than in case of a stove; a sufficient ventilation my then de gensrally obtained by furnaces: the ain ducts supplying the different stories only require to be properly proportioned, as al rged ~ explained. This is preferable -to depending on reg isters hich are merely accessories. The Mite ets are sometimes placed in the floor; although som times necessary, this permits the dust in sweeping to. easily fall inte the hot air ducts, so that the air passing apes these ducts becomes charged with impurities. This air ales renters vertically and ascends too direetly towards the Kei te When the openings are placed vertically and in the lower p Part of the wall, the air enters horizontally and mixes bette with that in the’ room; still, they should not be placad on thy level of the floor, because the warm air would then take up + the dust from the floor. In order to make room fcr the air introduced in this manned an equivalent volume must der. removed; this removal mav cn through the crevices cf the decors and windows, as is most COR: monly the case. But this natural ventilation is very irregus lar, and ventilators, ete., are frequently placed a little bi low the ceiling, through which the air escapes. This is wel but draughts of ccld air may be caused, if the supply of ainr® through the registers be not sufficient to cause a slight ex tess of pressure in the room. In any case, the sections of = the outlet cpenings should not be se large: that a double cum rent, inward and outward, may be established. It is preloaae to make them smaller and more humerous. They sheculd also beg Placed as dar as gossible from the inlet openings, so as tq prevent the formtton od a direct current from ons to the: om er. edhe: the furnace is sometimes added the use of a fireplace in the room to be warmed. This produces as powerful “ventilat iam as mayb be desired: the draught caused by the chimney increaw ges the flow through the furnace; the action of the two appar atuses my be so regulated that they aid each cther, and that ‘there is no entrance or escape of air by the docrs and windows Jt is sufficient to properly propertion both, according to the heights at command, by the methods already ind teated. It igcs ‘evident that the more active the ame lesion, the more heat 7%, hwill be supplied by the furnace : ~~ In case a fire- place be used, we think thatt the inlet open ings should be placed in the floor; if they are in the walls, Pthe horizontal current of het air would pass almost directly: to the ftre-place. The air w\ld then ascend and afterwards =e - = , Mea hy OS Psp Ne m pe als Bien * & 4 ae v8 2 ~HREATING AND VENTILATION. 3 164. ani=toe-enter the fire-place, so that a better mixture oc¢- The’ hot air openings sheuld be partons at a distance | the fire- -place. In buildings of considerable importance, it is absolutely nates dary to add to the heating apparatus, ventilating appara- tus, fire-places, aspirating chimmeys, ventilatchs, etc. ,; - without these, the introduction of warm afr into rooms of con- siderable size would be quite uncertain. ‘ ee by Steam. --- Apparatus for warming by. steam is Jess economical than that for warming with afr, because, Bes the boiler where the heat of the smoke is absorber by @ second system cf apparatus i@ required, where) the restores this heat to the air. But it id practically O bag pranaport hot air to a great distance. Renee nt from each other, it 13 Gecaccars to increase ‘the num =: way of furnaces. The first cost becomes quite large, as wel! as that of looking after the numerous apparatuses. With Steam heating, on the contrary, a single boiler or group of boilers can be placed at che point, under the charge ofa single persen, and steam my be taken to the required dis tances, in all parts of the establishment, without any very appreciable less of heat; the supply pipes are only a few cen timéetres in déameter and their surface is insignificant tn comparison with that of hot air ducts. Thus, the use of stear 4s very advantageous for large systems. Ancther advantage of steam is, that it admits of getting t heating to acd very quickly, cf foreing or reducing it; it very easy to effset the effect of the lowering of the temper sure during the night by a stronger firing a the mernine: t circulation of the steam and the heating can simply be modif- ted by slightly opening or closing the ecu Uh aii This adan- tabllity mkes steam very valuable for intermittent heating, Varying with the season, as that of theatres, for example. One objecticn madé to steam heating it, that it steps toc @ickly, when the steam is shut off: that is the reason of th use of stéeam-water radiators. ‘When the steam is shut off, this water slowly yives upi its heat, and maintains the des red temperature in the recom for a certain time, » it should be noted that all chance of fire disappears wit) “aia mode of heating, for the botlers are placed ocutside the wuatlding to be warmed: only steam pipes are placed in this, and thege are of ‘small diameter and are easily tsolated. T These qualtities are of Breat value for Vitrartes, record cf - eet and museums. «. ~ : ‘Besidas these advantages, gome serious inconveniences must he S > tas aa he c sia eaamaeaieiae oe per eeeny $007 £8 ee ye : HEATING AND VENTILATION. =... OS eT eS, be mentioned, such as ae real complexity of the = Somine and {ts-supervision, eaused by the necessity of regulating the istopeekks of the different pipes and radiators, and.ef provic- ‘ing measn for the air to eseape from the apparatus The return pipes amy also leak at their joints, witch inju- res the floors, walls and ceilings. It is therefore very ese- ential to ¢arefully look after the perfecticn of the joints, if these inconveniences are to be avoided. The objection is also mde, that this apparatus makes diaa- greeable noises, when in begins. to act. This objection is net very sericus; it my easily“be avoided, if the steam supply pipes are suf fietert ly large, so that the velocity of the steam may not be too great on entering the radiators, also King care to remove the air from the pipes and radiators by. means of special stopcocks. But, as already stated, this con- Plicates that service, 9 ! As. for. ventilation in connection withes steam heating, the Same is true, that was stated for hot air furnaces or stoves. The draught height of stoves is hot comparable to that of fur naces. ‘One advantage in’the use of steam is, that the air is hever made too hot, never brought@in contact with surfaces at a re heat. Uf carbonic axide is found to pass into the hot air through. xh xpiknxg,red hot iron, nothing of this kind can cc- cur in steam heating. Alse no smoke cah vass inte the hot air ‘through the joints, of which there ts always some danger in ee best arranged furnaces. The conditions of the ciréulation effd mixture of the se air introduced into the rooms to be warmed, are nearly th same as for hot air apparatus: the same necessity exists ee introducticn and removal of the air. Finally; the use of steam is objected to on account of the danger cf exploston, which actually existed in the apparatus frist constructed, where thes steam was used under high pres - eures. Accidents have occurred, but they have become impessi- ble, sines the use of steam at a pressure but little above that of the atmosohere. Heating. by Hot Weter. ----All that has just been said with regard to steam is applicable to het watér, almost without mod ification; the necessity of two systems of heating surfaces, and the advantage of extensive systems, resulting from the Slight loss of heat through the suppvly pipes: a mild and régu- lar warming, without smoke, ete. Apparatus for hot water has less flexibility and elasticity than that for steam; but, on the contrary, the care of the apparatus is more simple, which is a sericus advantage. The use of hot water is always indi- Cated, when a non-intermittent warming is required, but which . “HEATING AND VENTILATION. “Gelu ace wreer t be ¢ constant and - regular, like that of hospitalee for ex. Mixed Warming. <4: In recent applieations to hospitals, the thres systems cf warming have been combined, using steam, het- and hot air furnaces: By: this” ‘combination At’ Was:.-s .. , to retain the advantages of each system, dovitar ues ite. inconeniances. on is. yaehane onployed for transport ing- ‘the nad: generated this also nupplies @ motor for.accesso- Le: yf a special botler, a s would de, the : sgh bate ‘been uiped<". Every compli =. i ce ka « ofa pol the air become by the steam. serene ra. Tha veby tata ined. y has, to. phen San | a vertical duct, fren - inte eyeten appears to Sen aay the antages ae it is: ra they complicated. ‘this. mode of eraing igs not Pereran ly econonica); when thie. prdoucts ‘Of | combustion. directly pass into the room to be warn- ‘ed, the heat. As: completely utilized, and the economical dis- advantage. considerably reduced, ‘but. this unhealthy mode of heating can only be accepted for vyestibules, shops, etc., where the air is frequently renewed. | When the products of combustion are removed, the utilization of the heat is nearly the same as in stoves or hot air furna- ees; but, the heat furnished by oe gas being: glass walle, the haat is considerable. Heating: oy gas is proper only under certain gonad tt tens: when rooms of but moderate size are heated, only intermittently; er ‘for a few minutes, as deessing and bath rooms, etc. [fa fire were lighted ina fire- place, then fuel brought into rihely cz “peted rooms, this would be so inconvenient, that yas would be ; preferred under such circumstances, Cas cannot be used for regular kekaingx heating. wc HEATING AND Vat TILATTON. VEN MLARION. aes at qohioey we will, ‘now ind{cate the pre- pa ee to. ibe pala | for ‘removing from the room a quantity cf . So ened ce Peat ein sufficient for the ere Shane 2 3 of be very va ete). Pacsnee ice to the season, ss, temperature, the dimensions of the more or less rs; besides, the air couhd not ‘be: removed with cert- athe points where a is most vitiated; the purest. ate. in the room, finally; i wollte often aan wi ek aould ee almost cepaasg once le poe the a ee PraAngemeats, apo ch 1s ei m of ventilation: thi. eittaa a heloiee “tae RUT" “rooms” beciped ae a cohbitderas) p. number of persons. It is further necessary to remark, that in winter, .¢f th apparatus produces a certain supply. of air, which eduses a cor Pesponding escapes, ‘nothing of the kind exists in eammer, when pakoy means of ventilating the room exists, other than that of opening the doors and windows, unless recourse be nad .to spe- cial arrangements; this primitive process ts not“generally applicable; it becomes dangerous at night, and the currents ‘Of: air ghia’ produced render the room uninhabitable in the day- time. Hence, after having examthed the different systems em- pleved for winter. ventilation in detail, we will itndtcate the -preeautions to be taken, that the apparatus may be equally satisfactory for the requirements of summer ventilation. _ fvery system cf ventilation comprises the introducticn and the removal of air. We will successively tndicate the princi ‘pal conditions required to Babigty both, tes BAT =m at (BE SOS ‘ ‘ rd aay & c i t 2 eae 1.2: 4 P vg i : tot soa ane 4 ; , Sits Yet a a Ar Beran * . 3 HEATING AND VENTILATION. .. é Tes. \ Introduction of Air. --- Air is introduced by heating ap- paratus, or threush special ducts, arranged similarly to these of this apparatus. The precauticns are to be taken, which hae have already been mentioned in treating of heating. Care must be taken that the air tnlets are not exposed to unhealthy ema- nations, to any dampness cr gas from the soil, impregnated with it, from sewers, etc.,; these must also be as far removed as possible from the outlets for vitiated air, so that there my be no fear of its return through the tniet ducts. Frequently, in order to obtain purer and freshter air in summer, it is taken from above the roofs, through vertical ai: shafts. All emenations are thereby avcided. It has been muck iisputed, whether the air is fresher in summer at a certain height, or at the level of the graound: observations show the former to be true, though the reverse is often the case. The important point is to place the inlet opening in a well venti- lated place, secure from anything injurious, or from the @f- fect of surfaces, which might heat the air in summer, or in winter produce currents of a direction opposed to that of the hraught. : : [It is important that these ducts should be sufficiently Large, that the maximum velocity of the air may not exceed a Maximum of one metre. The greater the velccity, the greater he resistances and the losses in ventilation. Hence, the himensions and number of the ducts should be increased as much nS permitted by the location; that is the reason why the ar- angement Of these ducts should be made by the architect; when his is done afterwards, as frequently cecurs, ina building piready erected, it is difficult to find sufficient room for he due&Ss and flues, required for heating and ventilation, and he carrying-out of these operations is always affected there} When, froma necessity of arrangement, a single duct intro- puces the cold air, which is distributed to several stories, are must be taken to insert partitions or divisions, extended sufficiently far to enstre an equal distribution to the dif- ferent stories. The velocity should be reduced as much as possibdle in air Shafts, especailly at the points where this air enters the rooms, So that thisv velocity may be sufficiently amll, that tae © rrent of cold atr may not fal] upon the occupants: this current must be dispersed in the surrounding air on its entr- aneé, which only occurs with small velocities: it is therefore necessary to increase the number of the shafts, the number of the inlet orifices, and thetr areas. In England, the air is frequently intreduced through the in- terstices of the floors, which are covered by carpets, to bet- ter disperse the currents of air. But this has the incconvyen. AP ae aa nt a ae ak A H@APING AND VeNethAPTON. 189 okie of constantly raising the dust. The position of the inlet openings and their inclination should also be studied, so that the air current, may neither fall.cn the persons, nor enter at the height of the lungs. Temperature of the Air. --- The temperature, which should be maintained in occupied rooms, varies with the duration and the frode of occupancy, with the gpeater or less activity req- uired in ventilation; the more frequently the air ts renewed, the higher should its temperature be. The average temperature in churches should be 142 18 to 16 in offices; ¥6 to 17 in hospttals; oven 18 to 20 in theatres. : During winter, this temperature is easily regulated by the. heatétng apparatus; but this is net always the case in summer; the air is usually introduced at the external temperature, which may be higher than that desired in the interior, so that it cannct always be lowered to the desired point. where eel - lars of sufficient depth and great size exist, the air my be passed through them and thereby cooled a, littl®, whch progres ses but slowly, in proportion to their great size. , D But this only produces sensible results, when the cellars are quite large: the air will finally heat the walls of the cellar, if {t be not very large. In England, for cooling and at the same time purifying the air, it {s sometimes. passed through a layer of pieces of coke, supplied with a constant stream of water, faftling on its upper part; a shaft has also been filled with ceke, moistened by a jet at top, the air ascending and passing slowly through the coke. Recourse has algo been had to jets of water through capil - lary orifices in a water pipe,: thrown across the air duct. This water, mostly reduced to drops and offering a great surf ace, partly evaporates, which! lowers the temperature cf the aftr as much as 6 or 10°. aS Cocling mixtures have also been tried, but these systems are complicated, expensive, and hardly adapted for prac’ \eo- The production of cold by ammonia, ether or sulphurcus acic applied to the manufacture of ice on a large scale, cannct be advanaageously used for the simple requirements of ventilation Cooling by the expansion of gases wil! perhaps ~be better a- dapted in future to the applications here considered. Air its compressed by a steam engine, Icsing a portion of its heat, which is collected®by water in the. jackets of the compression eylinders, and my be utilized for other purposes. The air ‘being cooled, it is allowed to expand freely, cooling consid - erably in expanding to its original volume. .It ts evident that with a sBteam boiler for the service of the estadlishment or for warming, an air compressor might easily be adied , ra HRATING AND VENT LATION. : 170 dc iven by steam in Summer, and that the hot water could be used in kitchens, for service, baths, or for industrail pur- poses. pha difficulty has not yet been practically sclved. We shauld recollect,, in speaking of the temperature at whic the air should be maintained) that. account mist be taken of the heat produced: by the respiration or, transpiration of the occupants, or by lighting. When the quantity of warm air or cold. air to be introduced haa been determined, and its temper ature, {t must be considered that each person produces about 100 calories’ per hour; a candle 100 calories also; an ordinar} lamp from-300 to 400; a gas burned from 600 to 800 calories per hour, according to the quantity of gas burned: on an aver age, about 700 calories are produced by the eombust ton. ef 100 litres of gas. Removal.of the Air. ---.The removal of the air ti most fre quently effected by the draught of chimneye.. In the more sim ple arrangements, the draught..is produced in the chimneys by the difference of the temperatures of the internal and exter- nal air. + This draught. is very irregular, since it depends on this difference of temperature, and is generally insufficient, so that tn buildings. of some importandé, it is necéssary to warm the foul air by & fire of apparatus placed in the aspira ting chimney. The draught is thus increased, and at the same time, the ventilation may ve con ipal led by méans of the warm- ing of the air removed. The ducts, which transport. the air from the rooms to the aspirating chimney are arranged similarly to the ducts for fresh air, so that the same observations apply equally to bot The velocity should not| exceed a metre to avoid too much loss from friction. At points, where the air is ‘Pemoved from the. room, the velc city should be fess than in the ducts, to avoid currents of air injurious to persons near the outlet osenings; still, this inconvenience is less sensible for the removal that the intro duction of airs. Morin's experiments show that air passing intd a room through an orifice retains its form of a jet, its vele efty, and directly impinges on obstacles, while the aspiratec 2tr flows from all directions. towards the outlet opening, whib whieh it therefore reaches with a slight velocity. The velo¢city)of the warmed air in the aspirating chimney mug must be at least: 2m, eontrary te the statements .for interme diate duets, so as te ensure sufficient stability of. the cur- rent, in sptte of the efiect cf plunging winds, and of ether obstacles to..the draught, des cribad ‘in Speaking of. ordinary chimneys. The cocling of the removed alr must be prevented as much as gossible, or this must be compensated by+an excess of 3 om ” 5 a DAAC » “HEATING*AND VENTILAT LON, 1 V7} ont faa, R The cooling ef the removed air muigt be prevented ye much as possible, or this must be compensated by: ‘an excess yf, heat; therefore, aspirating chimneys are frequently cons- ‘pucted of stone masonry. *The top of the chimney must be furnished With a cap to pre- vent the entrance of the rain, andp protect it from plunging winds: cowls and ventilating apparatus are emploved, As already stated,. the outlet openings must not. be so néar the inlet openings that any. foul air may enter through then. Pinally, when air ts to be removed from several stories, care mist be taken to sufficiently prolong the duct from one )story before it: ends in the main chimney, that one of the cur | rents. of foul air may not be more powerful than the others, | occupy the entire chimney, shutting off the others; this acaution is also useful, when certain ducts draw more strong y than. ethers, that the air may not enterthrough the fatter, “thus reversing their action. . . Systema of Ventilation 5 iration. --- The vittated air brought. from the different steries by the ducts may é remov & es several different ways. Through vertical ducts, which prolong the horizontal! ducts foe each story, the air may be taken to the upper story, where all the ducts unite in a single aspirating chimney. The vitt ated ‘air is then heated in the upper story. This is termed “Upward Aspiratton".. . A central chimney extending through the entire height of the ‘stories may be arranged, into which the horizontal ducts dir- pect ly terminate; the heating then occurs at its lower end. .. This system. ts termed "Horizontal Aspiration’. ) The duets may also be carried down to a collecting chambers placed at the lowest point cf the cellar, and which opens into the ehimney there; this is called ‘Downward Aspiration". *Finally, certain constructors employ a mixed system compos ed of the first and third systems; the upper stories have upward aspiration, while the lower ones are furnished ial: downward wr ake oy We will study each of these aspirating sys teme snd indicate the mode ¢f computing the draught of each, and of determining their vrinetpal dimensions. i Warming the Afr removed. --- Whatever system be adcpted, i is necessary to heat the foul air in the aspirating chimney. the most simple means is to place a grate in the chimney it- Ba1f, on which fuel may be burned. To obtain acces to this, t is usually placed at/ the bottom of the chimney, below the point of admission of the foul air. The smoke directly mixes with the air and all the heat of the fuél is utilized. With Om oe as bV Fe ee 4% Ty, Wea mee Sen, S i e $ a Ties aD) ae | pREATING AND VENTILATION, 7:2. DT RERA ahranzonelt . it ts eerential that the draught be assure “SP avoid all return of the gmoke inta the atr duets. The fire “@yace may also be placed at the side of the chimney, with aa lich 1t commintcates; the openings for firing and cleaning ane placed on the outer sides and are more easily accessible (than in the ftfrst arrangement. é The air is. moet frequently heated by the smoke pipe of a hot {Yr furnace. in winter, the heat contained in the smoke and @t emploved tn warming the fresh air is thus utilized: during the summer, a small quantity of fuel {@ burned in a specia! Beto the smoke passing through the Pipe of the furnace, with ; in the first, {t is nowhing at the bottom, ts maximum at the tep. As the draught depence erature, it results that the same chimney removes in the: fires case, than in the second. Lilie eneral principle, that the foul air should be ped is Tow a potnt as Possible; we shall therefore find | @conomical advantace to be entirely on the side of the sys tem cf "downward aspiration", in the examples te be censidered hereafter, egy We will in¢identally remark, that for ventilation, the heat produced by the fires in the heating apparatus may be utilized espectalily in the case cf ordinary stoves placed in thé rooms to be warmed, whough we must beware of any allusions in regard 40 the value cof this; a single fire only remcves from 10 to 20 ‘™c. of air per kilo of fuel at most, and these figures are insignificant in comparison with the volume of air, which may be removed by using a kilo of fue] with any cthersystem of ventilation, | . The foul air may also be warmed by gas burned in the aspira- ~ting chimney. The apparatus is very simple, eonsisting only of a burner or series of burners. This mode of: ventilation has been Sspecially employed for ventilating water closete, where the gas can also be utilized for lighting; it is-suffi- cient to arrange an opening in the aspirating flue at the same height as the burners, covering this with slags. DeRelacouk.: ‘HEATING AND ‘VENTILATION, : 193. eight as) ‘the etenor, covering this with glass. This very dimple and efficient arrangement is unforturately siege 2 en Aecount of. the. high vrice of gas. ~ Cees oe in England, the. ordinary chimneys” for heating are ‘also much nged ‘for ventilation. — It has been geen that these. fire- places are of very moderate aug. for warming, but are really aspire- ting ehimn neye. The advant | of this arrangement, | very fre- Gosh Lao employed for. 19 ‘ abe | i a rte ith sie ie results; the great. ‘ineonventence | yentilation are. inseperably connected, 1ld nor fo ow the same variations as aetive in summer, when there ce Flee ventila-- “Rot to be the cae. nd eet las Boe: © by “sadtastone ut fer the wards of ? t aT phe Hear™ is. caeniest eft De ‘ore flue; improvements, which convert fire-places into hot 38, the e cnomical effieiencg is. ELS ea ees tc 2 © her modes of warming. : 181 fu ! very abundant wii, costs very ‘ calitie so that. the ladt objection ts of tance there. _ es ic 3, the wards oc ‘hespitals and ks a @ there generally smaller than is the cus- > that the Becond objection As of less imper- “Finally, te remedy the ineonvenience resul- ting | from the mtuad: dependence of. warming and ventilation, the Mnglish take. care. to add te the. fire-places: a very care- ruth y. arranged | ‘system, principally for natural. ventilation, which corrects the. irregularites ef ventilatenn pesulting from: ene. / fire. Zach room has ‘at least two cpenings for admission ef air,” ‘one supplytng the fire-place, the other. ‘feeding a spe- etal. foul air duct, whose action aids. that. of. the. fire- oa seb, This: vertical foul air duct is always. placed at ‘one Bide, not | epposite the. fireplace; the inlet. openings are as far as pos- stole. fron. the fire- pla and the, foul: ae ‘ducts i t is sought to aroid the. establishment of or ‘circulation ina portion ef th “the room only. — Besides, the. inlet openings and the crifices rete inp. access to the foul air duct, are located in the upper part. of: the room | ‘Experience appears tc have shown thas tc be athe best. arrnagement for marae the Mapnine: and ventilation as uni form as possible. | “The: proportions adopted are as oliove: one square inch in aoe for. each: 50 cube. aan pee the foul air duet of the up-. Se Bs a bse a . ; ee. ee p: «ore yale j q i ' hs : { nae HEATING AND VENT LAT IONL. : olf a eed, « ‘ , which corresponds to 4.8 84. centin. per mc. . pees” the Tie rest being. more, igo lace ‘and gives: more flexibility to the euuita. less aTue. that the natural ventilation produced, tar | ir duct depends cn the difference of om and. that of the exterior; this ht; the ventilation dees net ab- ut becomes quite Laree or and in- | bi bpeningbs. --- It ee just been a he openings for admission and extraction ed n the upper ‘part of the room, that for th fire -place. being at the bottom. To de- is is or. if net mest pational, the movemente oom must be considered, “according to the | es for admission and extraction cf Ss te remember that the a ~f One ithe es BAA? ahs y Qa zy 5 33 - Aga s ’ P : o aes so ee air. of the lower part would be ae. HIDE OL quite warm. aes aw lay- ons! erica ot ee oan would De ye stagnant — warm air, and the air of the room would \ ~e @ on the contrary, the inlet orifices ware placed in the ‘upper part, as in } , it is evident) that the entering cold fair is compelled t© pass through the layers ¢f warm air, which - is agitated by ita passage, and carried along towards the fire ‘place. The temperatures are thus more uni form- and the air is more regularly renewed. $ ” doclivicd "HEATING AND. VaN? LATION. Weg ky aed ae 3 As for “the. outlet openings, if they are placed in the upper Fea part, “the warmest air is removed, which is inconvenient frem the othe of wes view of heating; Still, this arrangement has ‘the advantage, which probably caused tte adoption, that the foul air is at the same time removed at the bottom through the fire-place, and at the tep through the flue... As for-the great (cest of the fuel, that ineonvenience is mach less in England than eleewhere. Besides, this. arrangement has great advanta- ges in summer ventithation, as will be seen hereafter. ‘ arming bY & Stove. -~- When a fire-place is used for warm- 6 air is always removed in the lewer part, and may de ced a@ desired. But if the heating be by. a stove, on ontrary, ‘the atr mst be introduced in the lower part, tlet poe on Le can. be Placed above.or below. Ree sf the outlet openings be placed near the ceiling as in No mS the warm air Ui » from the steve passes directly towards these openings .and immediately passes out. The room. is filled with ccld air, and the renewal of the air is very im- perfect. If the foutlet openings are * le¢ated below, as in No’ 4, a double ; the very warm.air, which leaves the stcve he: eeiking; to make reom for this, an equal velume r muse escape in the lower part. A cireulaticn is “esta d. shed, suitable for making the ‘temperature. uhi form, *, Maha bela the atr. in the different. parts cf the recom. Tt it. 18. eviden nt Ec nied =e heat - carried away Z DO Atet: his Furnace. _.. When the ogt at is done air furnace, Dy ores or by het water, the inlet and a ee SOR CNS outlet openings can be % ZY qr 7 | ee placed where pre ferred. To place both kinds cf openings in the upper part would be a bad arrange - ment, eines the air would Pass dineetiy from cone to Nee WE the other; this ineonven- Etence would be mach less if the openings ware placed. below, as Pin No 5, for the warm air would tend to ascend, which would | oppose 3 direct passage to the outlet openings. [pr a room cf Pat Be size, this arrangement might be very acceptable. It . -furthishes a vretty good renewal of ‘the alr, with a great nit - formity ef température, on account cf she mixture of the lay- ers of aim: Still, it has the disadvantage that het air open- Bn te et > Pin AD nant the warmat rp c = 7 as : BEAT ING: AND VENTILATION. — i7é. layers of ait: ei lay “it has the disadvantage thatowiew atr 0} ngs near ‘the, floor gixeet the warm air towards persons | the: ‘Boom. ete {as on No @, the warm-air ‘openings. are placed verew; and et openings abeve, ‘the fresh air would pass too dir- va rds the latter, a ant ‘too great a loss of heat would m % bie ae : ' © geal f 3 n @ lacs combi A 7, the inlet. openings are lcca- ia near the ceiling and the outlets near the floor. The | t then tend t end; it is in some degree a the @ room, Wa ORS Y ou ae here is ne ‘Tess nes hiaa iy ait ena ‘denser air biting: wee ee Ain the upper : Our Ua soves tote well on the. fact, that. the intro - Ue the tnlet 2 a y tron ene roth * a agte pig aele but the pete air ay 11) eh i ty eat to obtain. as low a temperature Oe . Yeu and outlet openings. are near the nati te g, re ‘Ne 10, the fresh air falls, from ce greater density, and: the. warts aif is 4A pemoved, Ava tig isa gocd arrangement. | Finally if the inlet be belew and the ourlst above, as in No fen the war- mest air is’ still removed, and the ar- rangement may be cone (deed a good one. To compare the two last arrangements . oy Tas “BRATING AND. VENTILATION, es 197 ee fourth his. the inconvenience of letting the fresh air des- cend too directly on the occupants, and at the. same time of- fering too direct a passage for the escape of the atr. No 10 | 7 t mixture, and does not permit the fresh ecupants; it only peaches the lower ted and partially warmed: this ar- onvenience. ,» unless the stcry is Te rehark case iD, abit pe pete: atmosphere, and the éiprrent \é fl bf, OR: the contrary, the owest, ah oe may. pesult from the act- : 3 ly occur, or the room is suppliéd r from. cellars, ‘ete., the current «is then rever- ds ITE ah ris. warmed — in the aspirating chimney: this in- convents ce § less to ‘be feared. se From all this 1t Pesults taht, in a ‘general way, the outlet ppenings for sumer ‘service should rather be placed in the up- per part. — The opposite arrangement {s bést. for winter. Hence ait the aspirating. flues sheuld have openings near the fleor and the ceiling. | ‘The lower ones are dati vans in ite ee the upper ones. ify sumer, 3 4 But the mo: ‘t imporasant. oh eit’ ae to madleiply. and Beatter the inlet and outlet openings as. much as’ poss gible. Volume of Air required. --- A difference of opinion has ee existed as to the a ie of air required in propertion te the nium! er of ‘persons occupying the. room. Theoretical consic- erations are hree of small value, as experience | can alone de- cide. ‘a ate Ge feo veatiy eee to eet geectae at wkat moment the air becomes. dangerous for respiration. We know that res- piration produces carbonic acid, whieh accumulates in the air, pif this be not eonstanly renewed. en ae ee so oh a | ania 42a a a om £& to satisfy ‘tthe requirements. ef both winter and Bummer service ~ Sore ads « bee ak oi he slat gyre tk » HRATING AND VENTILATION. ee | 178. hige hday he. not constantly renewed, but earbenic acid is not o itself. absolutely injurious; if ite presence in large quanti produces. injurious results, this is beeause this gas cecupies “the place of the oxygen, required for respiration. ‘Tt if also known that air, which ta tco damp or teo dry, : causes. disagreeable sensations, aK may, exert an injuricus ef feet on the respiratory organs; ‘4s then necessary to main- stain a. certain degree of ere ie by disseminating the wa- ter vapor produced by respiration through a suffictent yolume of air. But {t is not the excess or abcence of humidity whih renders the air deleterious, as atr vitiated by respiration quieyly becomes. 2 Spectal hhenomena are produced in the. resoired air, which “are not yet understood; mMiasmas or.germs pass into the atmos- phere, ‘atid develop, ferment, deeompose, @6te., according to nu merous. explanations having some connection with the realtty, but. which have no fixed basis. The cdor is still the most ce tain. indfeatién ef a vititated atmosphere. It is. well © know that the averkge proportion of earbontc acid. in the air is .0005; that the respiration of an adult pre “ad it 20. grammes of acid per hour; that if the propert- ion’ of: this. gas in the air ts not to exceed «O01, 20 m. ©. of air. must be supplied for each person per hour. A man alse produces about 60 grammes of water vapor per hou Lf the ‘surrounding air be half staurated, it contains about (6.4 grammes of water per mc., and if the degree cf saturatio shall not. exceed three-fourths, corresponding to §.€@ grammes per mC. 20 me. of air must. be ee aaah to each person per F hour, re Lene But if the Sor toindin Bair were a aka two-thirds saturate -eontaining 6.5 grammes, €0 mc. of air would be required per person per hour, so as not to exceed three-fourths saturation. Although thess observations my.be only indirectly connecta with the true causes of the tnsalubrity of the air, it ts no less. true that the proportion of carbonic acid and water in the ‘air increases with its insalubrity, and that there exists a@ certain rélation between these two phenomena. Fence, one phoula no® be surprésed if experience leads him to adopt fic- ‘es which nearly accord with the fotiowtng. preceding. Tt is now generally admitted that I8 m.ec. fer each ohtids and 25 for each adult, ts a mintmum which {it {s imprudent tc ‘lessen. Whenever any special cause of insaluBrity is added tc the ordinary results of resptration and transpiration, the preceding figures should be materially tnereaséd. The following are generally adopted: For infant schcols, 15 to 20 me. per hour per person. HRATING AND VENTILATION. Sete © ‘For ordinary living rooms, AO 40 60 tEc. “Siw: For hospital wards and unhealthy workshops, @0 to 100. or surgical wards of hospitals, 180 mc. ‘small-pox hospitals, 200 m.c.. “For lying-in hospitals, 300 mc. For stables, per horse, 160 to 200 mc. “the lighting is of some importance, an additional vol - air is required, based on the following: yr a candle, 6 mc. per hour. a lamp with large burner, 24 mc. | h gas’ burner consuming 100 litres hourly, 25 me ‘ ,that in spite of the dif-. density, a greater provort fon of carbenic acid is @ upper, than in the lower portion cf a room. [t irst sight, that a heavy gas like carbonic acid to remain near the floor, but the different gases x with each other, the carbonie acid being dif- ugh the entire mess cf air. The same is probably ee eects acid. ases lighter than air, like ammonia, whey are alse cd. pafough a room and do not collect in its upper i. the lower, rather than in the upper, part of é pyentilared. “HEARING AND VENTILATION. Ee _ NATURAL 3 PILATION. ‘DESCRIPTION. c o§ | 2. Action. --- We have already seen that a “Circulation Ng air may be established ‘by a simple difference of the .temperatures ‘of the internal and external air. During winter, the tempera the air in the room is almost always higher than than mosphere; alse, the draught caused by the heating ap ings air into the room and remeves a corresponding tl, this removal must not be tco difficult, or the | of air would be materially reduced, if not Stop - ally, any obstacle to the removal, eager one to fon as well. mmer, the internal temperature is usually ‘lower P the atmosphere. Hence, with an opening in the wnother in the lower ee the air enters the uppe mut of the lower opening, the air ni the room dein aht outside Lt ontrary, ‘the internal temperature is ee uld- enter below and escape poh’ the air of lightest. ; th walis of sufficient tigclknoas and sheltered | cecupiad by few persons, the descendin ig current Wot case will be found. In a rceom occupied by a eon number of persons or during the night, when the @x - soe the internal retaining the warmth accumu la - the ascending currents of the second case ; summer or winter, the movement of ahe aixgay the crevices of the doors and windows. I[t is that, under ordinary conditions, 5 or 6 mec. of air But we have times stated that this mode of ventilation is trregu- d frequently insufficient. Also, that the walls are dc completely prevent the passage of air, when there is a ‘ ifference of pressure internally and externally; the of the walls is suffteient to pass, in certain cases wae Ge Of aif. per hour and per ms. of surface. This an interesting fact, but it cannot be made sAhe basis of -an fFeient system cf ventilation. | @fPrintipal Arrangements. --- Movable transoms are frequent! | pMaced in the walle or the windows, but this permits the cold pire to fall too directly on the heads of the occupants of the room: so it is essential to place them close to the ceiling, “and at an inclination, so that this is thrown on. the ceiling, @ine there dispersed. These openings are also furniahse wit utings, which divide the air current. 16h. ig rae nace veil of hetght to estab- : og i inner pipe isa Itt Ure ‘entering air. ‘etroulates | ‘ie ‘the space pipe 8 This. apparatus 42. usually fixed | pote. the room, ashe inner pipe being © aes eae acting in Neigh hth of Maver is also an aspirating But Pipes) obi a aed some of these , the others removing air. This duct Hd nashog on four nee covered Ny ting **> pan] Cae : | ie eons , af. it is tHouiht proper to take he tres air from above the roof; or it may enter throvk | 10 ntal duets to the floors, through those of the not_ used druing = yi etc. eke aaa POs - oP erdae of eed iee to that of any ! necting the room and the exterficr; the effect f thetr. action. ts: determined in precigely the same manner as pfor ordinary diumse a) *s Wes will now show’ how to estimpe ‘the volume of air removed 3C-= pe ee te ee ae PE eeiUiomccgte HEATING AND VENTILATION, - | ‘162, yan Appanconen? of this kind, merely in consequence of the fference of the internal and; external temperatures, without rming | ‘the air remeved. HONS a | PHRORETICAL FORMULAE. | ae Let % -- temperature of the Poem, Q@ -- the exbortey tempera- “ture, H -- vertical height of the duct; in treating of the “draught cf chimneys, we have shown that the theoretical veleci . +Y,, of the air at the outlet is: ¢ v -- ++ BBE H(t - 9) 1+ a0 an valogiaybet access er the cold air, taken at the exter-_ ae nal heey ts: hes od Vii > a9) oe at Ae Hewes: suppressing the. term \T + 20, which differs little or eS we ‘have: cae . 2868 id aaa Q) sa ; ot + at [hts te. “tne: Riese bien] velocity ef the atr. Its actual ve- ous is reduced by resistances: for evacuating ducts for na- tural ventilation, their arrangement being usually quite sim- ple, and leading the air directly te the rocf, the friction fg the scle element to be considered. ne Letting K ~- coeffictent cf reduction due to friction, the Looe velocity will bev -- K V or vy’ -- FV’, and the our- PSN. or inlet of the duct. This coefficient depends on the ratio of the length of the duet to its side or diameter; Table46, which is a reproducticn ees Table ‘20, permits its value to. fe | found at once. Knowing ‘the velocity of the air, the volume removed per sec- an or. per. hour is easily found. If the section of the duct be By then s bs oS she Te lame per secend, and abo 8 Vv -- the ees per*hour. =~ * | ‘ _ PRACTICAL, ‘RESULTS AND APPLICATIONS. Graphical Tables. --- Table 47 is intended to Sage the . computations, and give the theoretical! velocity V, when the hetght of the duet and the difference of the internal and ex- ternal temperatures are known. To use it, first find the pred uct of this hetght H and the difference of temperature (t - 9) the value of this product being fem on the horizental scale; _ the ecerresponding theoretical velocity is mrked cn the verti- eal seale. The temperature written on each curve is that cf the interior of the room. By: means of Table 46, which givés _ the value of the ccefftcient of reduction K , we will solve | tkerwurtexs (the various yestions preposed. a Bxample 1. --- Assume the apparatus to act dur tag the mon DO genths of heating. The external temperature is - 5} a hot air ' furnace mintains an internal temperature of + 15. 1000 mc. ye ey Mipinedt ent: HEARING AND VENTILATION. > s:s«*DB ir are ‘to ‘be removed per hour, or about 300 litres per nd, dugh two Me nas aed ducts. Bis Tt. high, The total Dlookubs rhe d¥ tharckes of tem- Seep ee x er ie 320. Ascend a ertical 320 ‘s 5, and a horizoen- tal gives about 4.5 mo! an st : the velocity. ext. : t of redu 7 Him tel | length of the “tts side_ te ‘be .26 mm: — O79. fat a as else daand side é d be abeut . 27 m. ftead of square, its area quare secticn being Say « 19uld at least be .20 X . 40. Saab eed be increased, as no ac- eacncehertiggd at inlets, bends, Hane as re ‘the hias 3 @ for. abe second story 78 12). |, differance of tem- per ; product 280. ‘BY Tale Av, Ane theoretica! velo- Betty is So Bee De an ae | Me do determine’ the coefféctent. of ‘reduction, the total length of this duce being but 23 m , assuming its side ries 2AM... the fatto Ld -- 82, a Table 46 makes K -- .43.° The actual velocity. “is. then . X 4.08 -- 1.70 Ble, With two ey as in the first story, each must remove 125 “Jitres; with a veloetty of 1.7 m., the side of each should be about. aT Thy ‘or. between . 27 and .28.. The ducts of the first and” second Stories should then have about ae ual sections ro Ay RATING AND. VENTILATION. SE ieee, cae aga ‘Stories should then have about equal ‘sections, 4 explained. ‘bythe facet; that if the draught be less” he Quinte BAN, the volume of ats to be removed is alse. Bel : Soppose. the ie ae of the two ducts to be= > BR 28 Me with the same heights, how much air would ther ve. ae summer, the external and internal temperatures betng and |! for. example. y For a first story, with a’ Hed ght of 16 m. and a difference ' temperature of 3) the. product is 48; the corresponding the- i velocity. is about 1.75 m. The Patio Ld -- 92, and in Bee The actual. velocity - 45 K 1.78 +) .74 om. he volume removed -- .28 ce PaO ae 7A -- abeut .O8f8 mec. ver cond, “oF 208 io, ‘per hour. Two ducts would pemove about For tne Becend : story, “the height th. 13. m., difference of tem perature 3% their product is 39. The theoretical velocity ts arly 1, 60m. The ratio Lapa -- 82, maktitg K -- .43., The tual velocity ie AG OT BO Gs Bo m The discharge then e “+ BB a .GS == . 054 mc. per deccna, or 194 mo. per - ™wo ducts remove 388 m.e. per hour. . is apparent ‘that the volume removed would be cons iderably Atminished . in summer, on account of the necessarily smaller fferen of temperature. ifferrance became sero), ‘the ventilation would imme- Lely cease, only recommencing after the warming of the in- ernal air by respiration. The. external &émperature may be higher than that of the in- “terior; then, in spite of the warming of the afr by respira- P tion, the circulation could not be bstablished tn the same sense as before, but it would be peversed,a and. its velocity of circulation ean be found by means of the formulae and tab- les prevtously employed; only, the difference (t - @) would ave to be the excess of the external above the internal temp, erature, -- (9 - t). This tnflux of warm air into the room would be agreeable, anc besides, {t would soon warm the inter- dor of the poom, so that the circulation would soon slacken anil even completely cease. . These observations show that we cannot depend with certainty On Natug#al ventilation in summer; it cannot in any case be considered as a regular means of causing a renejal of the air. y! Note on the mest general Case. --- In the preceding, fric- tion has been assumed to’bhe the sole element of resistance, which it was important to consider. Thig is usually the oane:. for. the forms of ducts for natural ventilation will usually be very simple, free from very numerous bends, changes of section etc. The coefficient K may be taken Slightly smaller, to take account of these necessary resistances. i] Lee oh a. ¥ ig Ey.) HEATING AND VENTILATION, 185. + Se pies triet account were required of all these other ele- f loss, the mode cf procedure would be as follows. By méans of athe Craphical Tables 22 to 30, the losses corres pond- ing to changes of section,, bends, and friction, are to. be de- termined. Where a change of section occurs, the values D, C, E, and F, which express the losses of |e (page ¥7), should be mbltiplied by the ratios + s , s being the section cf the outlet orifices, and s the section’ at the part consid. The total of these losses ts to be feund as exvlained in cur “the flow ind vette thus obtaining the value R,of the istance. : @ coefficient by which the thecratical velocity must be iplied, to obtain the ac thal yelocity, reduced by all fstances, will be 1 -=. (1+). Table 48 directly gives the value of this coefficient. ‘Thus, by Table 47, the theoretical velocity of escape of the aS re found to be 2 m But the duct.ts 30 m long and . 30 m. sqhare,. with. four rounded bends, and two abrupt bends at 60. Required. its. aetual velocity. There Ag: an. @brupt reduction at the inlet, when the air pas- soe, from the room into the duet, which is 45 by Table 23. Pesvidh teh «ng the ecefféctont ©: for each rounded bend is .3& @ val > of for each angular bend averages .75, or 1.50 for the two bends. _ .The ratio (he ef: ‘the engin to. ae side, -- 100, and for Pehae? ratio#, F -- 4.50 by Table 27. The total! ef these losses ~<« .45 + 1.40 41.5024 4.50 -- PC OBy i: Taking this value on the horizontal scale of Table 48, we obtain..32Z on the vertical scale as the coefficient of He - duction The aetual velocity ins Be Se OO. = . EA mm. The Table just: given. serves for all computations of the kind when, after estimating ‘the resistances, it is desired to finc the corresponding reduction of velccity. It may be employed “incall bik paso of wong lation pPreated hereafter. re 3 HEATING AND VENTILATION, f* 186 R VENTILATION BY HORIZONTAL ASPIRATION. --~ We have previously deseribed the = Ae arrangement of this mode of ed Bag 3 draught, which is also rep- i vo Te pepented in the accompany- 5 prs Mee wa tng figure, the air ‘fs in- bh ',' troduced into the room ‘through the ducts of a hot SA ee ee AR gee - Oggi EIT, VOILE. AP furnace, of-a stove, or oo Ge : y Zo 6S through spectal horizontal YA | Z 7 duets, from the céllar, the a7 i: Z ae if, ete.; hence, the . TYE: ZZ BLL | Je@ngths of these ducts may @ Zo (be quite variable. aA Z Po. BY a special system the ae 2 wiair tg then remeved to a Ys a a oe vs commen chimney J, usually Tig || @zmmmaaaa Scentrally located, where hasan 4 : A ‘, the foul air is then warmed Z 2 ‘by the smoke pipe F of a Z * |i furnace L, by a special 4 | .fire-place C, or by hot wa- ayy || tey or steam pipes, etc. ''This ensures the draught ( and may be regularly employ ed in all seasons and at ine 4 r all temperatures. wae | «6 The velocity may at mest ees cae te be | to.1.2m in the ex- tracting ducts, but should at least be 2m, in.the aspirating chimney, to as- sure a regular discharge. v In the system of horizontal aepia@ation, the section of the aspirating chimney | should vary at each story, proportionally te the vol- ume of air passing through ume required to pass it per second, by thie velocity. - PO eR at, ai ‘ TSN ats: HEATING AND VENTILATION. | eB « bts necesaary to so regulaté the warming of the foul air as to" actually produce the draught thus as sumed in advance; this is. SARS seerely. x6 ae the regulation of the quantity of Lfuel- r ban a “phe. thoes. Bipres ciae. pnts pit pani of Pe hae: remains the game as in actual opr ee eon the theeret teal bis hae -etng: 22 ae BS ae Mea a3" gr a) at e the eer er the. oe eves being oles | A a? the external temperature. iia thes.» very simole and frieeton . But in the much more Lific al ventilation, it se tc This is Sac tah. "Tab le Ag ma ¥ ves oo actual velo- Vode la atte sum of ble must be Peateint au by the qquare bs, OF ‘the ‘same ge eh of or melo - obviate the nee Sraaat A ae ct aty ata be of three ysement ig to be wentilated; the chimey is cent- a nearly equal number of rooms on each story; it must Valera: troteach’ story on.all- etdes, at Least 500 mee fa per hour or 140 litres per second; abeut ‘1000 m.¢. from each story per hour or 280 litres p > second. This makes a total of 4000 mec. per hour for the ‘four. stories. The heights or. the stories. ‘and of, the aapirat ing chimney given in the figure... (Pag ge/st). epee Assume * the external temperature Fo. he a an average for of a PE 20 of POR Ge “RRATING ANT VONTILAT [ON. a hc P88 abe ae of warming. - The. dimensions of the principal parts 3 of. ‘the System, and” the quantity of fuel requilred to produce Vay th, pempera ture capable of giving the desired draught, are t be Pounds. 3. at Gel te te will examine ‘the eondttion. of Geen ctory Subceatye fy | Third Stor <= The. Tength of thé fresh air ducts supp}; : “ing the» Bpon. is gtven by the tabs ae as well as the number of ben de. ers 87h: ae mai tes | he extracting duet s also indicated on “the plan. Assume it to have two bends :O m Seioles ae ‘the ee) in the ex ak ant atiace: tor fresh. air; 2m. for the vertica] section of either extracting or fresh a 0 that its. side ts .376 m, ¢ifsquare. Bate for admissicn, and also for extractio 40 distribute the air to several! points, 1 these secondary branches must be slight, vir my not enter the room with an inconvenient. t may then be neglected. Still By te ‘cons ider them, by assuming the length of t greate ‘whan is: actually the case. The num ‘¥ b But it is usu consider Seda branches; it ts sufficient erally mate the. elements of. resiatance in the prin- uct and especially ite developed Yength. te ‘two ducts are. ‘preferred tof one, the side ef each should be. - 27 m. ng) total length would be doubled, -- 2 X 20 -- 40 . ments might be_ introduced into subsequent compu ta - ‘mode of calculation being unchanged. J eding remarks are equally applicable to the extract The air is usually remoyed from the room through fices connected with the principal duet by as mn ut ne ve elecity. in these branches being small, ss may be neglected. — If this were. Bbewi se, rodedur has just. been indicated. -* , nt po ts. being fixed, the sections cf differ- ent , PARLE OR tne” chimney are determined by. the condttion that the velocity shell uniformly be 2m. The upper portion. must remove. 4000 mc. ‘per ‘hour, or 1. Illm.c. per second. It section is ‘then. Tidllet 2 -- 56 a Pt ite side .7h m., if sq The second portion only serves three stories, removing 3000 mc. per hour, or .64 mc. per SOR ORT WATE: ‘section ts .42 me and side. eee; m. pea tt The third portion only iecha ree 2000. m. pre hour, - 855 several o Pango 4 ELOmme® Sela: ¥ ” . can AS 46 ent mt mite to brigie’! no} DS Sei : ape AND VENTILATION, = 788. .28 me., and side .53 m 98 1000 mc. per hour, .2& per second he and Bide TS ey cw WwW : oC a. losses, indteating the el- red for the use of ieaoly. Graphical Table, given by | -eommence with the resistances in the cucts, after- dering the apsirating chimney. (In this and the sue nds are assumed to be rounded, sO as x. Uf anediany. Noh nes 30 by 1.00) at entrance of frock atr auer, vatio 0. O. 45 eo 2 ae “30 ais 0. 60 75 -- 53. (No 27 yo) 2.60 ; © Sabo Feem, ratio Q- : oa — | 1.00 4.55" 0. 45 pene dtameter, more. 7 Seen are é 0. 80 “+ 40. o, ary Rs, pct : velo- ape eg to. a ms | the ratio of ‘ Tp 2. 5 (No. 22) 0. 20 ed b casi enprance to “eatmney (Xo. 28). 0.30 3.45 otal. i | 8. Q0 ws t velocity. tn ‘catia’ portion. of the circulation is an that at. the outlet of the chimney, we mst multiply theliat lcipeee Cal the ratio of the yelocities, these Ked - then 6.00 X Merde BP00L 37" sistance ‘tn. ‘the dues is then peerenen by 2.00 ine shimney. eae (le te. WP ee (No. 27) 0.80 aia’ Totaly 2 were, "2. 80 - pia we will. ‘take 3.00, ‘for evra) as the Vike of R.,#% the tc- tal resistance. Then JT+R -- 4,00; K -- LY +R) -- - 59, the coefficient of peducticon. to be applied to the theoretical velocity. Knowing ‘R, the value of this: coefficient may be direerly | obtained by Table 46. The theoretical velocity ¢s found by the same process a1 - ready applied for natural ventilation. + For a first. trial, we will assume oe Sompeta tune as ‘the foul air to be 204. after being heated in the aspirating flue. uxternal temperature eh Raph acne! 23. Height of chimney 4- bove thtrd story 12 m Phen 23 Xx” -. 276. nding Sot u- “Or which gives 4.00 on the vertical.scale oretical velocity for these. eeeuEDs tons. tual velocity -- .50 X 4.00 -- 2m., which being the Pree tty y: the penpera ture of the heated air should be @ he leet conte,» we find a eiseicy in the upper part , 2 ae to. Ppiy #1600 m.¢. from the third the ae should “The gee piitecence’ ya that the : “chimney is increased by 5 m.; this por- is 5. m high and its side is .65 m To aes to. Be she io haan ror the third story -~5 a. 65 -- 6 0. 40 3. 20 f temperature ae By cw pee ig. 23: the ‘Then 23 X17 -- 3€). With 39! and 29, is Se. of: 4.8 m. The actua 1 ioe cohen in the itis he chee Bigs in the third, it would be assuredly be the ond; if the volume of air removed were to the apsumed quantity, the draught could be y registers, which reduce the section and discharge st i ne The fesistance is inereased by the fric-. he new portion of the chimney, ie age hetght. ts 6 m he result for the & Seond story: — | 3. 20 Hg earns 10. aura a | : 0. 50 NEY Na Yi pie aes Aa -3.70 + 3.70 and, K/.- 0. 46. ah 3 oe | + wt the height and difference of. temperature -- BOR For this and 29, Table 47 gives a theoretical i¥ © _ 5.40 m The actual ‘welocity =~ -46 X 5.4 -- 2,48 hat the draught increases for the lower stories. ee, ye to result for first story: 3..70 Lira - - 6 4538 -- 16. We 27). 0.80 ly Total. 4.50 As. R - 4.50, K -- about Cas, the product tg 23 KX 28 -- 644 Table 47 gives a ‘theoretical velocity of 6.15 m., and the true ‘velocity “2, 43 X 6.15 -- 2.64 m ~ Draught still greater. Sec a Bi | % “HEATING | AND. VENTILATION. a “191. rature of the foul air being raised to ee ‘the ve- ir tends to ‘become greater in the ee stort®s— But the current of foul air from the hbase- ef Jess velocity on the first story; ‘ita veLpenray is lest, iP aer eee tne oh aseurod by. the mode of Maipute> e ee the other stories NS ae Ae pail the pera | 3 ahs aed ee ae resistance from the Bren @ required te Roe | cases , the extracted air is warmed by burning gas gas or 1.5 me. produces 10000 calories, of a out 9000 can be practitally utilized, 2.9 to 3.0 6 burned per hour, increasing the cost; but gas ised in some. cases with advantage, being so easily ar- € ally. when the same gas: is alao used for lighting my pe practically assumed that I mc. ef gas will 7. 65. OF air aS an aysrage. g Surface. --- When the foul air is warmed in the a 9y the pipe of: a@ stove or ne the surface of; pthisi ust Toundsc ys. 2 the apparatus: is specially employed. for warming the foul r, it acts precisely like a stove or furnace, transmitting 11 its heat to the air. Under these conditions, we may as- ame 3000 calories to be trnasmitted per hour, perms. of parte surface. — rah she “ibe example, about 17000 calories being requi - Ci IE ate oT | 7D LAT IA oe. 182. the. surface ‘must be. 5.83 ms. If its totaT 4 f ed mounter onan ct Aue ays mus t be .21 m Nt beats xs ioe teas Le been aa oee Ily Gooled by warming air. he) heat which can yet be supplied — aonb smoke iia Sy on a Bt ve Pe, “The heat: @>) ‘transmitted by the tuh eg. urnish 1200 calories. ‘Therefore, the’ : 7 1200 ~- 14.6 ogee which, , and a ie » in if they Paieh the Hest. requt- it is 623sy to ue a eapestahy Or heat’ ar oddbed does not me be wa med owe CAs \pepehing the asptratin pom air is e) De any i t ‘HEATING AND’ VENTILATION. 193. WINTER VENTILATION. UPWARD ASPIRATION, ica] a Ces Bie oe The arrangement of thts system of Bi ) aspiration has» already been indieated. “The air is. introduced as in the preced- i ing cases. fhe extracting ducts unite eye in a principal duct, waren, Sih Ok “duets the foul air to the chimne ig is. warmed , “as in Ractventel: as pi - abel BYa. ‘special fire, or by hot : ‘This. a ye bone of Wasp Oia oni is more complex than the. former, being caused a one one Clee vad the air in the ver- Yy, Sd A. PULL DLL fe hee dunatdared: to ee the temperature Abas, VAR py | yy f TUE LLL sot Bo the velocity of the air in. ering the chimney is: wae piweee \ de dea Ge venetlee ‘vaclecal, pe TB aah ee AS ia weoT RG 8) aCe on rar This. hain is complex, but ts: easi- Ay simplified by suppressing the fact- ors 1+ a@ and (1 + at" ) ie Cb at’ ), which are of merely secondary hos: ee mauel es the formula to: ee) POL ee 9) \ The’ MeN 1s not Peters thy affected by, sed suppression. ‘Thus, - ‘assuming | ae (12, RY +4 ABS £ ws 40 and oO -- 0, the _ first formla gives. @. 40 mh. ag the theoretical velocity, and , the: second about @.30m This difference my be neglected in the kind of computations now considerad. _Craphtcal Table 47 will serve fn this Mi au ag ete. * £ * wTING AND “VENTILATION. = eh t984): 3 or table AZ WALL gerve in this case; but the. tempera- » & for each cf the curves is here the temperature t* fin. ehimney; it is aleo necessary to. take the sum of h(t*- 6) AMA Q) instead of H(t - @). <-- Assume the building previcusly Studi ed is be warmed by upward aspiration. 11000 mc. of air are to be er ed id each story ,; Making 4000 in all. We assume the Sly ens same. ‘The heights are given in shee figcire: the 3 velocities wee required, 1m. in the ducts,—-and 2m. in in ~eections cf the dects remain as befere; that “chimney is here uniform, ite side being .75 m., area th horizontal upper col Looe duct, jotned by the ng, and discharges 2000 m.c. into the chimney, with te Agls se Lae ite. section must then equal. inet of the conte the successive nee for each story. 4, %5 Teeotiwn de e@¢ion, ratio 0. (Ne 22). 0. 46 gled bende, rounded, diameter more 5... (No 26) > 3 0. 80 n hori sontal duets. Lapa -- 1B +. 375 ce ae | see 1.80 , L+ed -- Ks . oe 27) £00 end at aheuney: (No. 26). | O. 30 Pupt contraction, velocity changing from 1 to 2 iy ke of sections 1 2, (No. 22) 0..20 4. 45. : , Total. , : 8. 00 “Stoce tHe: velocity in the chimney is 2 ad l.tn the duets +418 necessary to multiply by the square of the ratio go 9. ich gives as the total resistance of the duct: 2. 25. rietten in veghesies deo Lat-d -- 183-.75 -- 16. (No. 27) 0. 80 be ae SS O6 - we will take 3. 50, for example, as the value of R, slightly increasing | the fecult. Then. K.--" nearly .47. (Table 47). Y . Assume the temperature %* in chimney to be 33° , oe =- eB: Rfor, the average of months of heating. The difference is 27° sand’ the protluct is 27 X 12 -- 324. | By Table 47, for 324 and a temperature of 3s: the thecreti - Pca) velocity is 4.3m The actual velocity -- .47 X 4.3 -- a4 O2 m. This being very nearly the velceity required in the chimney, 3g wil! be the Pemperature required for the 4 aoe ré bien gos gi aiht ee bang lh hae i gum ceqestonsegot Sree. Laat ag pete ‘Bae bite: ope HEATING AND VENTILATION. “temperature required for. the foul air. 3 yY. --- To estimate the total resistance in the 2 r and extracting. ducts, as far as the chimney, it will cient te add the. resistances. due-te the vertica! duct, igh and which. doen not exist in the third Ul ct Are 28) a Ris 13, die 27 2 ‘ Of das reasons Bach pire 2:75 as Seah ON Sa ae Q. 80 ‘3 AO a OS aa 3.55 Se a oa aay the product a7 ee » Since the height: of the vertical as. fer the thrid story, - -and the temperatures of the external air are 33 and. 6. Pease | i - 8 £8 =- 45, the height of y the temperature’ in the groom, and asthe: TaRSen: of” the duct, it is assumed that se ‘Near the eatlings {f, as in the figure, it he 1 pees he floor, this length should be +45 by combining. the’ two products. Table 47 | oP Maleing A x 4.66 ©+ 2.10m., which dite: {ttle eds the oe tyend for the upper story. E_ Stor - ee . 10, 30 ee m of duct. Lid - ang, (No 27 ) : 0.70 Wetalo og. i 11.00 | ne-fourth, to, bring. to velocity of 2 m. 2.78 he chimney. i . \ QO. 80 K -- nearly. 48. ae The firet Product, er. the chimney, remins 324; the second, | “for the duct, -=- 9X 10 -- 80; the difference of temperature ry Ley? and the length of duct 10 m. 5 ne total =- 324 490 -- 414. For this and a temperature of 33h Table 47 gives a theoretical velocity of 4.75 m The actual velocity is .48 X 4.75 -- 2,18: $8 Va) Mee “mek- be Ae HEATING AND VENTILATION, Ma ene ae 186 not. eek: different from that for the upper atorye ‘ Basement Story. --- As before, add the friction in the ex =. cess of ueneeh of duet, te these previously fund. Diet. Bm. ak Tonger. ne | cea \ Retéstances for first story: : 1. 00 *s Friction in @m of duct. L+-d -- 16. (No 27) — . 80 p be Weta oa) ‘One: fourth of this, as before, about. Resistance in chimney. — | ULES Wotal. . Peet -< - nearly . 45. Te. the constant product add 324 dad 9 KX 16 -- 144 the tota ‘i (468. Table 47 then gives a theoretical velocity of 8B. 20 e actual Leothceng -- 45 Kh. BLS0 eZ, BA Mm, ) r to ‘the: lower hhory, the dpauent will be very ehcy (ole oe n ease of horizontal aspiration, it would be sufficient to perform the ecmputaticns for the upper story only, neglecting the oth for which the draught is assured. ity of Fuel. --- The faw! air leaves the rooms-at 15° be heated 18 te bring it te 33. The quantity‘of hea for the total volume’ Of, 4000 mc. -- .312 X 18 X 40 ‘Calortes. Then 22484-47000 -- about 3.20 kilos of Sout pot ew burned, considera Paty: more than in the first case which Pesults f rom taking the air from the upper part of the stories, the height of the column of heated air. then being le fess, requiring more fuel to produce an equal velocity. If the warming is done by gas, steam or hot water pipes, Proceed, as. An the preceding case. 7 es 2 “ht Pistia 2 ~" y | HEATING AND VENTILATION. | Pa ae tare “WINTER VENTILATION. - DOWNWARD ASPIRATION. ~~ ~ Theoretical Formulae. :--- The principle of this mode of Pee year Set el ge ee aspiration, inv ted by M. Crou- velle, tet that the foul air shz BAe St | be warmed at as Wat mlm Bs low a point as PAN ee ae: eee possible, so tha a the extracting ducts descend te the basement in 1 order to reach - the chimney, in« ~ -gtead of being "horizontal or as NW cending, as in t | the two precedan os Systems. — A reversed sy- phen is thus fe SNWoed, the draught _ -4dn this being p - | duced by the legg ; density of the _, heated air in th \SEE chimmey; but the , temperature of the air in the descending ducts | {fe the same as ant in the rooms, 15 } for exwmple; ite )» density is less than that of the ? external air, so that a draught i seca Ph. the inverse sense ‘Gis | ¢ . 18 estadlished t Bi Bellet eh tae the descending a | ) Die Pan nae ‘ LA LELLLLEZLLEL LBA LPLLLL A CHL eZ LEE TLEDECACOLOELL, YZ \) iN : | ERE GIW'W. —] 238 = * ou — 5 PT &, 2S aa eA Se 1 rare wean CT : __ HEATING AND varriarron oe aS well as the formula - for the. Pe bert - velotity of. smoke. dischagre. Referring’ “to tite’ erolanaticn ously given, {t ts eastly seen that neglecting the fac- rat and } 40, which very slightly modifies the true will be: (t*— 9) + h’ (t'— t’) | ata ets velocity y from which the duets descend; h’, the vertica! hei gh ‘Wand @ , ane. the temperatures in the chim- in the A and room, and of the external air. ; a DL Table. --- The Craphical Table 47 may be used ‘tn t 8 case as before. The difference of temperature. to be in- trod d in the geecond term ts t* - t’, orthhat betw Snathe TAD nak in the ducts and in the chimney. | { --+ Apply this mode to the same building. 68 air to be removed per nour from each story, or iall. The lengths and sections of the ducts remain ser ry game, with the came velocities required. The sec- Tareuue sion) as ‘before. A Extraction. brut contraction, ratio 0. (Ne 22). 3 O. 45 me rounded Fight angled bends, diameter more . thane Bee. e, yaa), SO Friction, horizontal ducts. L+d -- 1b 4. 375 ae SRO, OMS 27) 6 | i. 0 One bend, @ntrance of duct. (No 26). 0. 390 Fricvton in duct, Led -- 16 4.375 -- 33. mute woe IO One bend, lowsor horizontal main duet. (No 26). ©. 30 Frictton in do. L+d@ -- 25+.75 -- 33. | 1.70 Bend at chimney. (No. 28). : aoe 0, 30°. |Contaretion, entrance to ehimney, ratio 1-2. $0. 20.7.75 -? Potate 12530 30 Multiply 12. 30: by 177 to change velocity fron } to on. which gives ne 3. OT Friction in chimney. L+-d -- 33 #.75 -- 44..(No 27) 2.20 . Total. a ys ‘Take R -- say 5.50, and K -- .39. . Form the two products h(t‘- 6) and h'(t'- t') to determine ‘the theoretical velocity. The height h’ of the descending i si Y ahaay: Saat Baer | tT ha “7 HEATING AND VENTILATION. - 189 gs for thas story is 2] m.; the total height of the’ chimney 8 its excess in height is h -- 12m. 8 “tor a trial, the temperature t' of the heated air to) b re thas ‘of the. atmosphere being 6, their difference is 20} the first product -- 12:X 20 ~~ -240. The temperature t? of the air in the room being 15, for ex- ample, the difference t' -t' -- 11% The secend product is then SAN EC Eo <= 2a), making: ‘a total of 471. For this. value and @ temperature of 265 ‘Fable 47 gives a theoretical velocity. es 6.35 m The actual velocity -- .38 xX 7 2. nearl the required velocity. The air mist un The only difference for the second story he height of the vertical duct is 5 m. less, so that ton is.to be correspondingly reduced. Piction is; Laid -- 5 +-.375 -- 13. 0. 70. sg to be deducted from the resistances in the extractigz hich te done as follows; in changing the velocity ., we take one-fourth, say .17. This is to b6 rom the resistance found for the upper story, 5. | : be fas. Phen K --+ .:40, ght h’ is then 21 -- 18 m.; the excess of height ey is 1245 -- DE ve the differences of tempera- -— 340; the other is 16 xX 11 -- ; their. ‘sum is 516.: For this value and a temperature 26° le a? gives the theoretical velocity 5.55. The actual ve- Ag oe XK 5.55 -- 2.22 m., nearly the same as found for --- The same deducticn is to be made as for the ducts being 5 m shorter. The tcta! | 19 xee 8, 16, - sR. Then K-- about Ls ene, ae hi of the ducts -- 16-6 --.11 m3 the exce hh oe isiaht -- 17 1 8 -- 22m. Temperatures the same. The products are 22 X 20 -- “240, and PAs oe tele tote! ‘BGT. For this and a temperature of 26, Table 47 gives the isoretical valocity 5.75 m The actual velocity -- .40 X ye Be 30° mM, _ Basement Story. --- The deducticn is a little 2s cegieh Se as | the height of the lower story is @m. instead of 5 m; its va Fue is similarly found to be .20 instead of .17. /) The total resistance -- 5.1€ - .20 -- 4. be ok? ead. The products become 28 X 20 -- 560, and 6 X id -- 55.) Thet | total is 615. Table 47 gives 6.10 um ap the theoretical ve- Flecity. The actual velocity -- 6.10 X .4) -- 2.50 m. The variations of velocity from one story to another are no Bee ors laready meade on horizontal aspiration 2001 : ox RAPES. p hs x drafind = og eet 4a 474 ep Tae 800 is evident, | RK is Paurtevent to ioertor “required ‘computations for ae upper story only, neglectin lower. story, Tor) which the draught is. assured. [t will 11 be necessary to mke computations for each, if the con- be satisfied are different for each. Each story ‘be burned, --- The fou! air is to be _ a difference ef 11, 4000 me. of at => 13728 calories, “say 13800. Then fe coal per hour. [f gas, smeke Pe ands oend heaton SYS -- bec ee Speedie, and Oe acend oy ‘the service Sheree) of extraction of the dir vary fre rom 2.02 to 2.34 m with upward aspire with downward aspiration; from 2. Of aspiration. | Bren in the mest unfa ,, the extreme limits are so near each is easily made unfform in all stories we. have alec shown that a untform gh itself, the stronger draught of the sade i eaconad ew more one of the up- Fu Xs st. We found pees aspiration to require norizontal, t accieds kilos; downirs rd only and down - is then | the most ‘costly system, n regard ie economy, Be teat as uni formi ty of hg Oe wa, favored by increasing the height cf tk d aspiration should then almost invariably d being preferred, unless very serios ob- eho | abide. wet the building. % te \ \ LLB 7 tems. ‘The computa - tions for this arrang ment are tdentical with thoge previously ae 4 “ q P * : . are bee 24’ red ia eee an HE EATING AND VENTILATION, | oeuen ! oes DENT LLATION, _<-- During the summer seagon, the Textate Tee removing the air from the interior, ce mer from without. La of. suets, | simple ay eh oe eee or Levan ‘rooms, Ave ahem ea he. upper oper , Pour ip cee to facicitate O° oe the action of i “ueeatechisie’ a and LHe Sections re Ry “A Di bagi given for natural . ae eek are employed, the reduc- locity. will be quite gmat: the tem mion at entrance, bends, ate. , bu me the eceffictent of reauetion oa 3; two- thirds cr cone half the ae the Ghccan velocity of the air before, oe the co- Sith The. mode of “computation es similar, i th vote, cas@ the temperature of the air remoy ed Pas that. ‘of the recom 3 erature should first be found; the quantity ef h | sad by respiration te’ known, aa we) i as that loaet throu; the walls; the difference is the. heat remaining in the recon, whitch heat | mie interior air. Uf; for example, the volume of Oa te Removed. te giver, the temperature produced b? ig quantt Ay ‘of meas apr! ted: to “thie Volume of mir is easily pA ee OF tie: POM EER EY, ws limiti~: maximum temmerature is ‘the volume Gf Wie may then be found, 80; that the tempera: Mav not exce@d the limit, receiving thie quantity of heat. Application. Zxample saa school dormitory {sa te Weniilated in summer; it fs 6.5 X 1@MZB m., and 4.t o| aqageaar on JS bea ie Tan ‘yo tes, ae Syste DATING: og ENT ILAT ION: be Aueye 16° m.¢. cf bi kG to. ve memoved our, g° eo jaan! Wenderatire mus t net eae. ri 205. ce Required the sections of the outlet roi fi ce Sing SEU ness laters. ne r KA 2.90 de ep. ae ar: ‘ 65 Roganen: Rotereel ape guverial. ben- ves a lcss of ia) calcries” per hour per 2 Pies per m. 8. of wal; i BOY 5.or 6 220. 540, 7E8. TESS cals. ‘ yt hg thea. aah adult furnishes, 80 baie ke 60 for a. child. Then 60 x 28 -- _1€80 Ce! - as wo hoe! ‘assumed, Ve ‘eo oners the ‘pemoval of 500 mec. of air ae ec esd second, for ied ego reasons. ist: eee che admission of the air through the crev i- the doors and windows - and aise th the escape cf the air Te avoid. error, assume its velocity to be reduced OUT .70m. The total sectional area fer escape of ve M404L. 70 -- .20 ms. This area is required erin ‘but would be more than necessary in winter, when Nenbtgd a eatetere. Openings for admission Bt air ane their sec- mt pl eee Sn none the roora to be Ronin with a hor tee aesta line duct. An apparatus for warming the air re- i is placed in the cumrse of the ducts. The draught Lheight! is 1E mo; the external temperature, and that to be main “vara a the room, is 152 500 mec. are to be removed per Phour, or .150 per second. A 1B, order that the air may gel. alias into the atmos- OT a 2 4s Rey, " HEATING AND VENTILATION. 204. sipeephere’s at thevoutlet acl eel we assume the velocity in. the duct to be Sm. Commence by arbitrarily geehming the elevation of the temp- erature of the air removed ; assume this to be 20; the air then escapes at 35° «CC : br The product H(t - Q) -- 15 X 20 -- 300. For 300 and t -- 8 Table 47 gives a theoretical veloéity of 4.10 m THis is te be retluced to 2 m., se that the coefficient of reduction is 2.00 +4 4.10 -- .49. On Table 48, follow a horizonta! through 49, to its intersectiva with the curve for M -- .O45 for ord- inary chimneys; a vertical Jy gk hte this point gives on the hcr izontal seale 70 -- Ltd. / Since L -- 15 m, d must -- .22m, {f the aspirating flue opens directly into. the room +t be wen- tilated. If the foul air had te pass through a horizontal! duct to: reach. the aspirating chimney, to L must be added the Tength of that duct. Also, if the fresh air did net directly enter the room, it would be necessary to take account of the resistance itn the Tregh air duct. [t remains to see whether the temperature of the foul air removed if as assumed, and whevhes the desired discharge is assured. This disckarge Sime we oe Xk 2.90 --. 097 me., in- stead Or -150 mc.; this result being too smll, it is neces- sary to diminish the: témperature; assume t -- 3 Under these conditions, and by the same mode of prodedure, H(t: = @)) <= 270, me V -- 3.85; the coefficient of reduct - ion would be 2. 00 at -85 -- .52; then. L+-d -«- x about 60, so that d -- .25. The ec then ae Ob x SE x. BOO ¢.- e128 which ts still a little too small. - The’ temperature is then 32) and the side of the secticn about .27 m. Next esitmate the quantity of fuel required to maintain the ventilation, The temperature of the air must be increased 17: e€ach m.c. absorts about .312 calorie for an increase of 1; henee §00 a » 312 X 17-7000 -- .38, say.4, kilo of fuel required per hou lf the atr is net directly heated by the cembution cf the fuel, but by means of hot air, hot water or steam pipes, thi bur rae must be sufficient to supply 500 X .318 X 17 -- 265 calories. [t is sufficient te refer to previous Statements concerning these different modes of heating, te determine the required surface. Exampie 3. --- Suppose that instead of the mean temperature of 155 the’atmosphere is at 30? Assume a8 a first hypothesis, that the air removed is he 20, whence t -- 50. As before, Hit - 6) --300, whence V 3. 9 m. by Table 47; the ccefficient of reduction should be y 2. 00-4 3.980 -- .513, and d --- .28. The discharze then -- -20 % .25 X 2 -- .125, which is tco small. Bee Pe ibe a ate 9 HEATING AND VENTILATION, . 206. Assume t -- 48; the same process gives d -- about -29;. and the SNe aeons hos X.29 X.2 -- .166, whfch is teo large. Then m should be .26 m én its et and 49° be the temp - “the air removed. Mi et then de heated 49 30 hg, which requires 19. ee 42 kilo. ot coal per hour. re used for fuel, .30 kilo of gas, sx i hour are. required Oe: bie ea ae the But, as the s are. required, than ume er ‘air; Still, chim- eing ae m. , Sand ine side af ae eae the volume of air removed, : “ Sab doaier aah is 30° “then H(t = 9} , BY Dablo 47, velocity -- 3.60 mm : Maple 4G mikes K -- . 56; the actus The discharge -- .30 X .30 @ the air to bas. heated ie waking 1% ati80°° The velocity then -- 5. 15, and the xtetua | veloctiy 63m. The diacharge -- BEB. ma. ¢. d $@ examples enable us to state that, with the same sect- et 3a ff “aay he ducta, | ‘an increased heating increases the i a : As F BE ‘ime : Cy Sark \ ‘ leg a Wane ‘ie a £ we dae (em pals LR ee Z ¥ if edie HEATING AND VENTILATION, | 206. MECHANICAL VENTILATION. "DESCRIPTION OF APPARATUS. % yal Syed of Action of Fans. --- [fa cylinder, hazing in- ‘temnal partitions and being filled with dir, be rotated around ee ham this angeiade shh. ? ia eemminicated to the air eee it oa! ‘ ie axis, and Senda to. fohee che: air tow- ean, heat is rarefied near thee ete In. the convex surface, the air escapes; the canter of the. ends, — the air enters Eng. se which Ana hell account of the difference es - hed be tween the exte pr ¥ ting Rausiia omitted, the draught duct a aspirator. These. different na- nligand of stp cn As dia a uTtey, arian by “Stratght or curved arms are at- wings, by which oe Mote eeaae rey es. The ap- Paratus may be placed ei- ther vertically or horiz- ontally. Ths annexed fig ures indicate the arrange ments in use. The air en ters through the duct B, connected with the cpening of the fan by the curved portions, this opening us- ually being smller than the seeticn of the duct. The mouth of the duct is heim Mig dees an oe ae ‘furnished with an bearing par, tomate the support of the shaft, its other end resting on the support. ee A solid plate EE ig mounted on the ama re and carries the vanes A A. The air enters around the Shaft, comes in contact with the plate, and is thrown off around the circumference by ; aoe sath eo MES ey cc a % Seren ie ike te Le dnieY Poin ad , oes ‘ <9 Drage SS : : Soo ; Sorte, Sees TE , ie AND VENTILATION, 207. the vanes. . the pict} alone os alte Bto effect Pe The arrangement is similar, when <1 the axis is vertical; its lower 7 nd then rests in a step-vearing c . Bupported by the var across the “mouth of the aspirating duct B.;- the upper end is held in place by the neck a. | To prevent the air from escaping. Pienee? the vanes, they are some- Late times. placed between the plate & and a. flange non, which. ee serves to support them, The air then escapes: horizontally steal coon vanes. .A projection s : ees: also dips into a cireu lar channel filled with water, thus forn- ing a.water-jcitnt, pre yenting all return of the air. This arrange ment is only applica- dle when the velocity . of rotation of the ven tilator ia not great as the water would then be thrown out, ‘and the ‘channs! soon VTC emptied. | ‘ The: apparatus ef wl. Guibal ‘is also used, especially for the “éntilation of mine and ig usually const- ructed of very large size. The aspirated atr enters directly through the orifice 3, and-is expelled by the bys vanes A A, which move as indieated by the arrow. These vanes are connected by an armature, which strengthens the whole The air is either discharged diractly through the epening H, or more frequently into a chimney enlarged upwards, its lower section being about one-third the upper. The diameter es, ae aT Gir aoe f aie Pee ARR « 6 BYR PEN CHER READ eas ai : 4 ig wage pif) Me Ge Py eo HEATING AND VENTILATION. 208. of Acad opening B is commonly one-third the diameter of the fa: itself This fan has @ shell C, with an opening for the 4geape of the ain, occupying about: one fourth its ecireumfertnce. It really a blowar. It ig very imporatnt to regulate the opening according to the rate of speed of the apparatus, and the height and sectior ef the chimney: the opening is therefore furnished with a mcev able and #elnted valve, sliding between guides, which can be adjusted from above. This fan, whese diameter is @ or 10 m., should move slowly, about &0 resolutions per minute. It is” a general rule for fans, that their speed should niminish as their diameter incr eases. Otherwise, their peripheral velocity might destroy them. Foe Blowers. --- Thesa fans are arranged nearly like thoge al - ready described. B is the opening for admission cf air, A ar the vanes supported by the arms E,, Which are fasteneca to ti axis: 2 hollow shell T receives the air eacaping. between ib Vanes, and guides it to the discharge duct R. This appaxzatus is frequently double, receiving the air on both sides and ex- pelling it through a single duct R. It. is then wet! to se ar range the parts: EB as to form a complete partition, separating the two halves of the fan. The air entering at the right niet en check that entering at he B: HEATING AND ‘VENPLLA? LON, 3 i209. not then check that eneering at the left, an advantage, as al! shock or. change. of secticn causes a useless loss of force. The radial vanes are evidently mcre distant from each othe as the distance from the ¢snter increases; if the side guide were parallel, the air passage would inersas e in size, Sa would: cause a continula change of velccity and resulting les- ses of force, This. variation of velocity would also cass a roraing, which becomes very oppressive, if the fan is in an eceupied building. This chage of section is then usually cem- pensated by eaus ing the side guides to approach”each other, B80 that the section remains constant. Some constructors even ar- range these guides:-se as to contract the air passage. The shell T may be concentric with the ventilator as in the figure: but 4b is preferable te give it an excentric ferm, pre dueed by a spiral; from the point M the passage fcr the air thrown out. by the vanes eccupi eg. an increasing section until it terminates in the duct R; the distance between the shell | he circumference of the vanes continulally 7incfeasing. va haye just indicated a means cf regulating the passage of the air between the vanes by making the guides k approach each other; the guides may be fixed, the vanes only rotating, er des may be. attached to the edges of the vanes, connect- ing them and. rotating with them. But, in sither case, tne construction ste more complicated, than if the guides are par- All these diffica! - ties may be solved by arranging the vanes as in the left adjacent figure; the distance between two consscu- tive vanes then ‘being constant, the guides ‘may be parallel. The vanes may’also be curved, so that the normal distance bet- ween two vanes. is constant for their whele length. any con- atructors prefer 3 curved form for the vanes, s@ aB to effset offer to the atr a passage sulted to its resultant motion, compesed cf its radia! moticn and rotation with the apparatus {teelf. Most commiénly, the vanes are radia! with curved tips. The interior is also sometimes furnished with fixed vanes, to guide the air in the proper direction, after it enters the apparatus. he number of vanes is very variable; in some fnas there are of Ai he att 4 " . Py sie ig FY A a . HRAPING AND VENTILATION, 210. ‘ey € or 6; they are quite numerous in cthers > 2A email number is generally best suited to a large ete where they: Cannot be increased without great _ gost, and. when the length of the passage between the wings is e€fficient, for the air to fianally D calhbpsbpeey oe oa motion cf the whe Ie “eat on 3 pir ors and << The arrangement of this kind of fan differs in no way from that a)l- readyd deseri bed. : Bur @ lateral duct B is added, through which the aspirated air passes. These fans my be deuble, like bbowers. fhe general arrangement of the apparatus comprises an.aspi - rating duct B, which is made as large as posetvle, so as to reduce the resistance to the moticn of the air; this duet is connected with the opening 0 by means of a conical tube, through which the air enters the’ fan, this. opebing being much gma ller. ' he fan V is then driven by the pulley p and forces the ai into the large duct &R, connected with the outlet opening 0’ @ tuve N. The most suitable angle for this connecting cons from 6 to &,which is also evident from an examination cf Ta- bles 24 and 28%. Customary dimensicns cf Fans. Excepting for mines, the diameters of fans ac not usually exceed I to 3m. The inter- nal¥diameter varies wrx between the third and the half of the external: these limite should net be passed. The breadth of . AND VENTILATION. ‘for i fer single at is from the qu Pe iati ss 5O to eo pexolutions per minute fe very large fans: 1000 and a ed more for small ones. There ig an advantage in increasing the speed as TD ahteh as permitted by the solidity of the construc- ‘tion, for the efficiency cf the apparatus inereas- es with the ve elocity of es ty he rotation. te reassure produced oy! fans, which varies with their Sy oh pad is generally. between €0 and 180 mm. of nea cues ma of a Pk cps. OF: air. 3 5 te an as oS. ee ee "Weare AND VENTILATION. about 25 to ne We shall hocietite. give the mode of determining the dimen- sions. of centrifugal | fangs. For a rough approximation, preceed as ‘follows: the. er diameter of Eee © pened cs yanes iy | ag ‘*& he bie q, Be henum i ce ae It My, She. section of the n Stanateny tte area is : - 210 mc. ee SS ay. ee : : great oe PMelieolial Sérew Ventila- VO poRs. --- These are ccmpce- sed of a helix mounted cn an axis, the retation of which forces the air along the cylinder, within which 3 | ‘ it is placed. Thus, an ap- Sec clean ge es paratus cf 5 m. diameter, = Mla — : having a screw of the same Se eae -externald diameter, its pitch being 3.8 m, making 18° revolutions, discharged Il me., according te ex- Rae periments. : _Instead ofa cont inucus helix, detached portions of a helix y be attached to the shaft; the length of the pitch cf each ie? 7 ey i HEATING AND VENTILATION. i | AC ig f vanes consequent ly varying from 3 to 6. | “a4 ot kona BP OAT US is. eas 20 to 30 per cent. os 4 = RSP 59 i ed eee 8 ina double fan, each side Q-+ 2 instead of Q. lg. --- The radius of-the cpening Ses between the vanes, ig general - ae i ply dha tive 80 as to oleae the The pressure es the air with on leaving : ig next to. be found. This mist overcome ‘all resistances fren fricticn, bende, mges of. secticn, leaving an excess ef pressure suf fi - 1 part to the air a as ott | ecrrespond ing tc the re- Charge. . stances are. ‘computed as in an ordinary air ee etion of the air duct is known; the velume of air dis- . ed is fixed; the velocity is then found. It is then easy termine the resistances in‘this duct, due to friction, ete “Phe ame method — is applied te a plenum duct: the resistance ine this part cf the circulation cf air is then known. OS. this must be added the Icse_ from changes cf secticn; “there- is usually a contraction at the inlet to the fan, as in- dicated in the figure cnp pageg//, for the inlet channel is Mee : HEATING AND VENT (LAT TON, 214. mad? as. pe as possibls, to reduces these losses... The coef- fei gaat a ciee Vata reduction Ps balan from Table 23, and mu: : ae pinging | Ry Table 25, the value of the coefficient ‘may ‘be found, which is to be multiplied by v'*# 2 g, in crder - : Dh os dhe tose due. ee that Ceplasenia ge oye ‘SSdeaing at ey ‘hllavemese.. and Mau thereso. the height “requ huey produce the velocity y at the outlet of the duet, whic Bes “+ 2g, we have the total pressure. This should be “iner@ased by Gn? < fouthh, to allew fer the losses within the fan Pree! ae ae | 5 falocitty AS ae Outlet. --- The velocity v’ mast be known, in order ito Correctly determine: the loss at the outlet of the fan. Tb © find this velocity, ‘the outer radius of the vanes ‘aust ti st have been found, and which has not yet been compnu- ted. ‘Pra: biealty, it is best to assume this outer radius at firgty about twice the inner radius. Im @ general way, let r -- the ratio R, +- Ro cf the outer to the! vphiner radius of the vanes; then.v’-- .1047 NR, i+ Poet the’ pir. ascapes. radially from the vanes. If this escapes at a mean angle of) 45° with the radius, W -- .Aga7-QR$fAPZC er owe Tv -- $1047 NRW Frm 1.40 r. rie will: ‘easily be seen which cf these formulae shculd be us edy. or whether an intermediate value should be taken. ak ee first trial, assume y -- 2., for example; the outlet Vale) Gy. is thed to be found, the section of the rol fice, and ts een na ‘to de Been better this assumption déffers | anage from the results to be obtained hereafter. bei --- When the air escapes radial- -- Re --/RE + 685273 H+ Ni i : ae @ outer radius should be: ~~ NS ' HRhere represents a ee ain fot nape’ eal to the pressure produced by the fan. This equals the pressure previcusly \ found, multiplted by .0013, the ratio of densities of air and "water. -o (Uf the value of R’ thus found, differs too much from that "assumed in order to compute £z_.H, the computation is repeated /with an intermediate value, which will almost alwgys give a | sufficiently close approximation. Prey wey ae ate its a aa > } ; Imarmyc AND VENTILAFTION. : OLS. _--- The breadth b,of the inner ends Td be. 40 R, though it may be .50 R. a nearly constant section from the inne of the vanes. Radial vanes diverge Eavcnk rapreniie ¢ Bi miniehine their width. Their ety b, Re SR, if the the vreadth should. be an 34 tacharge ° and have de- Soe ocala wee is E. 2 ° arranged, that the sect then Meee ae ns ahs vanes. approximately determined as already m; the quotient MH-+t+N*is on the hori ie point on this seale, representing the odie vertidal toghe curve eens ae etecy at the Butter: the rat to Ry Rois “Phe pressure im = he Commence by find oe ig on ahs: herizental Seale. Since ently emj ® us ! on. ithe Caner “hand, “eh gim- annene employed te dirve the er acting on the engiffe, car- heat, unless Ate is an expansion | Paley a of the machine them Het Pecsttevion will Py 4 a the 4 fatne ett at pa sides; the may be regulated, “tndependently ent ae faged Maes! sar the air Ss ae ‘forked Pagiiiation. “and explain ;ions in past years. This system may be of the, importance of the buildings jus oa f very yenpers rs machinery and apparatus, or whe eins be cola motive force is ear og \ aed a ss yar ve aT EE yi ae Met res tc Feet. } tae EP ree HEB oh a : ie Tes ee foe Metres. Fest. Be 3. A80F Be 6.5817 Sey $. £426 i Ae 13, 1235 &. (16, 4043 (18, G£62 he 22. 8661 i ee 28. 2470. eae sdae lisa ‘Metres. to fneiiae Ot. Metres. Inches. oe 39, 3704. ae 78.7409 “11801113 - 157. 4817 196. 2622 | 236. 2226 275. 5930 314. $€35 354, 3339 Square Metres ipaq, Met. + Sq. Ft. i 10.764! er Alia. BABE. << sn 3. 32. 2923 ck 43, OBG 4 Bi 53. 8205 * 6. 64, $848 fe 75, 3467 8. 86.1128 9. $6. 8762 + ee OAARMP WY i. | « to Square Feet. hs ogee Owbie Metres to Cubic Fest. Cub. Met. 70. 6313 105. ©4629 L141. 26238 176. 5781 21). BE38 247. 2094 272. 5250 31. B40 CMD sce be 638. 315@ Pc Vide : aly. Feet to Metres. Fest. Metres. Ma G, 3048 foe QO. 60f6 a 0.2144 A. 1.2992 5. 1. 5240: €. 1. 8286 Tie Wil ace $. 2. 43584 7 6.7432 Inches to Metres. Inekes. Metres. oat 0. O25 4 sou 0. OBOE m7 QO. O7 62 A, | O. 108E Si. 0.1270 By 0. 1524 fe SO TKe 8. 0 2032 ay CG. 2266 ae HEATING AND VENTILATION. WABLES FOR CHANCING UNI Syuare Feet Eis vdtots L; oe Square Met. Sq. Met. OO 29 1656 27 87 3718 AB AS S574 8503 T432 - 8361 oe99909999 * Cubie Feet to Cubic Mstres. my th Cub. Met. 0. 0283 0, OBEE 0. OF 42 «Loe . 14186 TeSe . 1282 2265 20000 HEATING AND VENTILATION, EE CBT Be cee 8. 28B. Ba50 | an 0. 2265 | Se se a 317. 8408 | 0, 2548 | Klos, to. ite ee. ml Kilos. 0. 4538 0. 9072 1. 3608 1,8144 2. 2880 Vana ee ae e 2.7218 Nr a By ere! tare ae eel Od : en at wr aes 3, 6287 De Uae Bde: ee rk GA 4.0823 igr ae to "Fiireihbie! “Fahrenheit, to Cantigrade. oe Gant Dee. Bah. Deg. ee Fah. Dee- Cent. Deg. eae: Bee EA y iy Cannes 0. BHEC" 11111 1. 8687 fai ee a 7578 SPS OS 3. BB8D 4. 4444 5. OOOO Units to Calories. fone: Units. Heat Units. Calcries. 3. 8833 ©. 2520 TF. S386 . 5040 . 11. 2050 . 7880 ‘1S. 6733 - 0080 L©. B46 . B200 23. £099 .&120 27.7782 - 7840 31.7485 ~ 01860 35. 7149 ® 2680 a & Gt ee 6 wo > “I oS MPR ET canal te 24 ~, ne 5%] _ HEATING AND VENTILATION, © ER AR ‘TABLE OF CONPENTS, \ CP RO ie oS ee ee A ge Ate Reheomanoneld el SO Bee le Se rie See le 4 ee Bi oaide ie Re Fee te a ck Le Ga Re Deeg er GO, Be POM G0 UMsti ee i a OM NOR CS ie Sie a ak PRB OPOLEON EC eatee P es weer PARt toni ee meet. (oo - Conduetibility. Pee Me mee mle ee Re | Vaporisation. - ee et me ee Latent Heat of Vapprization. --°.-... Li “Effect: Ot Feat ane Hregture. a .@ Expansion of a MOLTO, yi hate ot eee Sk a ts eee tet ee of Volume with Pressure.- - . - we | Variation cf Volume with Temperature and es 4 Densities and GT OR Ge ce tees UR es < , _ Volume REA Weteht OT Bia Gn) ne “Combust ten, ere me em ee ee SG, a “Jadle of Calorific Pewees Of Fuels - <9. 2%. ‘lo. Compositicn of Air. - ie ee ee ee SO. Barciny of Air required for Combustion.- - - 11. - + Volume cf Produets of Combustion. - . -.-- 12. Dee Heat carried off. in Products of Combusticn. - 13. Graphical TODA e eee 14. Volume of Air required. - - eS - 15 - FormuFae for Combusticn, Agier ican Units. - -- - - 18, Traneniseton of Heat. throueh Walla. -- = -- - . 2 1... 17. 3 oe note with single Wall exposed. - - Se ee = LF, Delmer 27+ _Eellow Walls, - - Poe! Cee ee ta Cars oR omNrO TGP ye and Ki ee LS 9. oh ¥ * Ceilings and Ficors. - .- ee ee She Ga eeu tek DO. ae Oe ee ee sg Heat produced by BOSDITAtION,. = in = 1008 2 9]. | “Reat produced by Lighting. - - - OM ete oe te Oy hand of Plow Of Gases and Steam - .- - 2 2:2. ea a Le Orifice in a thin Wall. 23. : mow Poessureg.. =. 2 2 ~ = = -+%- 23, -Theoretica!) Velocity. Tees. Wichiliades adh tl ae eRe Be wrecMacee ta evetune, - 92 oo BA. Peemeen Terocteg Hi es ee 24. Prepon in Weteht. i Se. 25. pee ae Penh epaye a rs 25, Peecratee OF Steam «.- 9.9.2. 4. 2k. oR: Pormulae for Atr, Cas, and Steam - - - — 28. OQ 4 “raphieal fables. - ~ . - 222 2 Lf on, ‘ Note relative to Steam, - a PP « VO ONNIYY oor ww . ade eo = “ ERATING AND VENT [LAP OMe 320. sh Pressures. ea Se - ate 2 we = BS, Actual Velocity of Nea coe. - Sg oe nS CHS cca! of io sate and Theor. Velocities. 2°. | : Be ora) Es pine Cees ‘ By toe, = 30. Soe tee me SO, a Rae A em 1 dp rah. eee Bene ee ee ee ape Ye treet: mae ee ce | aes Gee ap 38, Pipes, - A es ne ke oe 1 boa Oe . bok nora AY, syelocittes tn larder ona: smi lier Re Al, phical Table.- - - ---- ------ AB)? 38 of Pressure. - - ee hae’ oe 2 42. ‘Bends, or Changes. of Bitedtton: (= 25). Se Sea. Angular. Bends. - - - - ge tenia hee Toe A, spear Rounded Benda. a Bs 7 OF AP Ni tad Wa RY ay - 42. ‘Frietion in Pipes and Ducts. - - - uni 4S. 7 Ratio of actual and theore st ical “Velsety. 44. ‘Graphical Table. - - ie at eg ait lee f Loss— et; Pressure: -. Bi yin iter ie Flow in Volume and Avetght. .. HEATING AND VENTILATION. Remark on Form of Section. Continuity of Discharge and Results. UME rt ime = > + nike ep on -PuetaTotal Loss of Pressure. - - cereale. Tables. - - - + <---> > : Ducts. Tobie Ain. - Direction and Inclination of Wi Modified Fermula for Draught. - Descending Currents. = -- i- 7 - - - Conditions of Sstablishment. Limit of Hetght. - -'- - - - 7 Obstacle to Descending Current. poiwanme AO. DS eMpTOYSd. Toy nie ect te | “Defective Draught and Admissicn of cold gy Velume of Air required.- - - - -- = -Fire-places fer Wood. - - - - Ceneral Formulae.- - - PATI INC ie VENT LLAT ION. - -_ < ‘ ©. ce ‘proper. MEE OG mon ei eS 2 f Chimney and eélihs: of ‘Room. gircular: ‘Section. - easton ota ties | Tafluenca of Height of Flue. Get ake of Section.’ esnpiera Sotiilas. ee Conditions of preper Action. - - - ; - Diemacions of Chimney and Volume'cf ‘Graphical Da es, ay ws iO ape ie Wee oe ae’ 1 20, Circular Section of Flue. - - - - - - + --- -121. “Ventilating PING Dineeee mH = ee a ety BS. : lighenke of smeky Chimneys and Remedies therefor. - - - -1)24. f | Defective [Introduction of Air. - - - - - -.- -124. ‘ | Temperature of Smoke too lew. - - - - - - - -124. art ane TV OLOONLOW. = sa Ni tm a hai le BA Communi¢ating Fire- Places. - See Se eh eh Oe SE BB, _ Communicating Flues,- - = - - - - - - - - - ,-J] 25. | + Js Plunging Winds. -.- 20 <<) -¢ <9 --- 05) - - we 88. Hot Kg MATNRC GG, eel ee ei ie Ce aie a os Sie SS oS SLB, . Volume and Temperature of the warm gue rie oy 4 “ HRATING AND VENTILATION. Quantity of Fuel to be burned.- - - - nGtane surface, 25.202 - La ee | Heating BALES Ga oe) aS Re ad Seette eh of the Flue.- - - ------ Sect en Of net air Ducts. se ee ee Dimengtone of Boiler. ae ae i ss ‘ Draught of Atr produced dy Radiators. . Supply Pipes; Expansion Chamber. - - - | “High Pressure; Perkins! Bvt emo ae se “Heating? by Cas. Bete Uk Nr. es ane RS oe la. ah tag oh of the different Systems of Heating. Feating with Products of Combustion. - Pita Dineen, 6 6. a a ee SUOV ME Aes ee eae ls ie SSS Mot Mingrumeced. (60%. a) cet Steam Heating. - Be eae ew ett weed Vaart Hot Water Heat ing. Meme en tinge Se ee ee ies Gas Heating.- --+-------+-+-- Ventilation. Ceneral Principles: “<9. 0-05 - + - $ $ 4 ‘ t ‘ 4 f t t ethic thes ome per ‘Second. ees: elocity. of Ce ote co te a teat. Wavles. o.. ee eer Se oe cus bua ese i oat wis +e HEATING AND VENTILATION. Necessity om Ventilation. tees rae oe BEARER EA Ae SBE SeGEUREBE Te Gress aeeeeae: tt mney Ser 2ae me BERG ERMEE ROS EHeeee gees epanansestenseretozeeat min Sesibastesiecaiforinzii! a Eiced SSEsHSBH G5: S000 Pete aca Sr anes go seeeeeaee et + Com sae eal saal eae cram a ¢ oducts o p,. mn // 3 x EEE SSISCEEITE se sfat fst? Saaieatitnms aSOGERGSREEEGsEueGoE< es" s St BRNO Some ecged BEER EE EEE EEE EEE HEHE PEE EE Baa eS eS SBaay sesa7 FEsas of a80 8200 ef 000 ceses sues" Gset0 03070857 °33 Sazag #aseasaaeasesuu{aafs beset sasea/asssstcastaeesessei2;.S¢ Sas azsd oufasonentegsutazsatantat insaicaze! scat eH SSSesHHARECSESEEEEcevbaaa it ocdits al sensassusveeee Birtesssttssits Sri PEPE Ssssesedasssiieti cosas ittaisis safes tantcaesrtaes BSEBazas vas sezesafad ses80 Qatar GuszefzZezzscicsasafosessssstie8 saeegtgccs nT SercSeeees Reeeeeee secennne L, Heat ost ja ble A > > f Oa I ee Siege Oe men eek 6 ee an ates : 3 - See Ps Leiak ah ee FaP aE — . rename Leg pce Aircacd Wiel fable 3. Heal bod wn J? tale €. off Corcheartoncper pil of Pec, Sa ARMREST rae SGU NUNEROGRUNM SHOE al Satan an tasdnaHceHia? an GeHe URAERUAAUCRERERERUGEAUGEGOEIUEN> ANGE HERI OUDEOENOES saa anne ttt a0 ae RaGGE et aceneces CEE DEAR MaRe LER BUNUN) 00000 00CBERRGEORSGRO B. tH ane ESSE CRGHTEGATTGAL SAGHELGGGRIENGUEUCEE CacuRNGEE Pee AEE SUT rg BEROEREE eT SUR RRRE BORE OED i aa PCC eae HIGaaHiM Gn Mt tcoe iuapeauditaatiit COPE aT Ee PONAEDAOGBUGAAGOAOL +c00A 00M G0 LEGS Ga ECGGTOORRT GREET BSONEGH PCUECEL EEE CPEEPECEEL Pee PRG CH! CHORE RT AMMABOG SUAEHURRGUEOCHORUORG ONRUBRBEOHUBER Pree Spoor EE a ee HERB GURERRAR DORR EOER BRE LE Le ag Hp paper BORRHARRRERRH NEY CHAD Bh GSU AURRARB URE RADA Ze RaNERE MERA LES’ SEELLEEL nha Sereeretee CAA eT TOE STE et ae ele HH ey fH pd BRARRENERRRES Bes ue) bt Lad Papp Te THEEEPEEEE rete " Haney Mian PErEEREES EE TA tt PA Pent TARGA Hae: tpt f= Pf pps fb RURERERERELE CT a Bs BRON gh hi Beat fe. hy Leo” Hie? 200° 20° Lee Oho. 280°. 300° premeed hese ke, ge x * alts, Ore loath oily, eppoorce. uoneas Gio: SE SRE Co a Pana : 5 Oe aD | GE ES BE EE Pup AE Ri ee es eo A ype : no é 4 gh AS TR TESA OI a A ES 2 ah SEES LD Tu, Pf tf A ge Pine.03 7 S Yo ate ( WE SS 4 ee. EN Ey, Od SP he al Sie SS cai? Ey Ay 2 0 EN BA, Os SE DAY LD A AAS BEEP ON EF vo AZO V VA ee By) EA OSA KS A ae Ae ee eh eh ay es AON eee ee eT ince OF pe Ay Ae ee ASE Poh (ae AZ Lo Zh A ae Yh oh WMA DB De Mh 0 Na aS? OT 7 ea tor ected oe ee Z4Z ae a OA a SO a as SS Oe ck NB HO Cie lh 8 (Ze T Gk san Ra et B BS Ss Z| ES eS GENK = eS NEEREBNNG RACES PANE NRUNHENGH ANKE TEs N Moar es los , S NONE CS N eee AN LLL A (LLG VAY ZA SENNNERE Z ae ALA LAT 44 Aa ee aw GeSG2RaGREZS APEC BER Eagar anne ah PCED Bue Stet way, TZ ALY Za Be sid (je PEERS eee eee eet i og /2 14 IG [P20 B® 2y° 26° 2 30° BE 34° 36 3k HO eek RESESRE “a ot Cukcucl act O plecwal Geacpucaliccs, Le ~~ Fa | j 4 x m4 " eine | e- =~ S mE Bes + ) ce BSB Se —+ + , } 4 =f e t c oats bis ~~ x 1 =) ~~, a & ») “\ S = Ss é a & A bees a aoe se * stibis mS : i | = err zt ed beat + — :: ce sete fe x : i | cs iM, + 4 ASSN a=. a =: I 4 4 yy: t + + + —}+—_4 +— + + + | + + NI ; ae ‘ ++ S < ae ; a ’ t — , : ; : ; ; nis { i SX) So ~s o = ‘ i sererdezes ss . segue Gceces! rep | Be | eae 6 4 ae t iy TE t \ SS S$ 8 4 pot tt tt Gs AS ‘eel aSeae! Ba sits a i ii 3 all atts ; a a : j 4 ae uf } 4 | 4 } = Siw i EE Sl G3 F es P : eS be iN = Mos S +. a: HP = a Paks = BS Ft a \ os HEL Gee Res sane gece HE le Pa ai art Buna AE : BR fone bt + + e etd eg ek ' } on Be: | i + | N NX 4 \ \ | EN N =i a Ae mean | i Srey) canst ates tees eeod cd aves sal pO eee Bee ore PARE IB He | Pb B28 pe a tht > s Fe : 4 a } HL T rE t e + t t | J : 1 | _ a : : : PS ie segues PE ses t t = we : S, . es IN ie Ng \ fe zi i + + a | us auue Soe e eee Ugueaoe WeEadcaaeaGeoae EASA PACES VLD AL ERA ee at Daan? Gene Renee oes mn aS LN ETRE EPS ENN t iN ee aS + = —T [ : as) S : aS Ge NS ee ee a a NS im AN a = eae ae FE [> ee & se [] : i + E bio RG K. c a i NG & | o Be B&B | i | ua aa Fal a aa 3 3 # - feu eg as Be Ln ~ zest | | +H eS S N : a a B a i ae ze F | Pa a Bs a a ag acs Eee. Bae y/ 6 ECE ECE EGE e A FOTO Ry GUMS villa PAGE0 47.48 DSR RRR Os REE eee Ree eee mine 9 27 d0R IRs aes PE Re ; a SRE/.0 400047 e0n neon es Oe ee ne ee ae Ri eS t a CECE ECE Eee Pett ttt ARRAN ARNG MLO eS SAM Mere aaa CO AA S00 RE DBE ee ee AZ BAW BASE P Anas OSes VAR Po eet oe pet tae Aaa sa seat a, a i sO tt in HB AAG AAA SS OA SEU BR CE BRIG RE ARS SS SEES eT maenene i ERBAUSEE LACH Ne WE IER EME Sees OMe Bee ae Prva Ae CUR eee it Ee a ee a eesepeaenne Sat 57 cad onand enaea tacts stand cntasoxzsa ized casey geeea are aetee f| t/ Seagauussssenogecsaueuilaneesucsaucucedueuany Was BEER EEE EEE Eee BEER EEE EH pee oe Al snoeseoougan CEE EEE CHEECH EEE EEE EERE CEE HCL = | PEE Lt a ee B See eee eee reas cuusa se ceecaasesudusesstfneeseauseeceat scan’, py semua 0obey Benes teens fee! Geeedecesnnaasesasaesedeanen nacneuae 0. 00{ 002, 003 .004% .00%° 006 +007 a 009 OO. Of ald, «0/3. Nah Ne tieeeaien ee wie a any ia re iy ks pe eS ide? ot bathed Ut ; 5 2 bs © Aaa Sees Pht 13% juste % Values of [tel aed Viper, Paes HT 9 53 eB Eg CR 1 ee ee eae ote oe garb SEBBSGRE SIGS SBE RREE Onn | Beogtagps Sek e soatae kas ie Rag bal ed 1 eee eae || Y i ay ae tat ) jeBe || 4 i ¢ i) % mee 1 a ed 8 HS DS 0 Ah) a WD Praia bee bared 4s BN - Pune 9) EM SS Ree a UP aa i Pa ee shi iss eat 18 Sh Ba | ; : wy, © 2a AS Vig OD mae ETS RS SONS SOR, 1a ry ae q bree i Tes te Pi, : ea aS i ud FREON Si te Thay. Values J [+ 2b and Viral. foo" be 2 Fe ear arate Sere coer eeereecesess pa A RS oe $5 pid PAY. PEt see Be SR GSR JS RRA RS GR A AG Bae SS SB Se ESS DS ; ant +4 CoC TPE ge F are Ss a E pee lane a oo 2eB Se DeRNake Ta x es es PS eas 2] on rt | S =i oS sea eT *e Rn sa be ot! wt : ie Semmes 7 tt a mend maak ggugegedn cr BREE B wie a ipo) EI ey WS Re MR HW me en, Pau Jn e & A ty S- / 95° 2 NY UaScmeae 15s. sie SR se sieeieiates BE Pairs Be a 8 + an Sep ise + 36 - ae Ls Bone q |_| cue es i Seceee Tae Cre EEE = ARE bi’ bu bepel ty Gp” re or, Bigs > eee ee ee + jleble ll. Thedpdtival Vilocity, of Gesee, ob vssr> Jorestenes ; ram f —— RA A ee a do RASBERARAL EERE CERES oo | - Pp beseatbaea dedi odtet onitcstace ptt +44 Oui HHH ey reaeae g x a bad Bae Rene had one dees oeeecuaenn v aaaG PCE EE [woe peea en aoe au v, si m | BEE Ee E JA Ld | sa S fot COCCI Sea : BORE GRRRR APRA ARRARN ALE ESTAR eae eee BERRZ32 | SEE NEE Ee 1k a MAVELROUTE TAMAR LA RY SEERERREGUGEGUEGDEEE y eC aan mm 8 3s BaBEn Gant Pe % | BAER zz SERBESGSUEERED? 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Rae oe 3} ’ ber (aa 4 } NM i te wey fe 16 i ik Sap emt thle Th eed om} BRe i — BN ¥ ‘S: : Yar 45 . wh 4 A ne mest act < oS e | maa As B mi : Wigene ¢ eat i i at ya hs Oe 2 a ek Gt Table 32 Chawmene, Dresesyhh, Velocity 44 Cacuye of jrdhee, 4 rs . 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PEPE EER y, 50 5 AN TTT oT Peo a 4B ac RSS So RSSEP aS T4GGREE NEEREEESRESR MGSGEETSS PGRES SERRE IS See ESEShE SR BRRRE SREB HATE Sc eRRBRNERERSERE Ce ee ee eee ee rene BERBER RSS RS RSE RR GRRE EER S EERE ER RS RE R eRe % 40 3:0 35 4. inthe’ TN Zo As £0 £5 0° Bid ‘ Se BS SUNUEus EOGUGGdUG0eSGR00000055n665R0800\ 20058555, ~ + SRBRRERSELSERRESSSESRARENSL EER Se ESSERE ER? uw POE SS eae ee EGSEESREREEREERESS EERESEPE SEES CRRBRBSRESE Seo: 68 eT eee SQRSRSREEN FEECEEEEECEEEEE EEE CEE EEE A en S Ser ad GRR RRR REESE SEER RRRESRSSSE AS ERERERERRRBEEASERER SERS Se SSS SBSRRRSETS ccc Bees! -\& Cette ee eee S TON Re Ss oes te eee eo ee ~ SS MS SSeS ™ ~S ~ > NS ss NS a - sca Synge yy fe spa |B rm Me ER Re eae. Cage 2. EOUESASS Oo fe ARR SS. ne Nee pvt rey Table: 49, Ob neesrncd of: Macived Vey é , 0 TOC ECE TT COO 7 ee eee ee. 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