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ORNL





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O'RNI - AC - OFFICIAL
MAR 23 1965
ORNU B-1068
A716.5
20.1 cery. 6501044-5 g
DYNAMIC GAS THERMOMETRY: MIASTO


20.1
ORNI -AIC - Olli
--- LEGAL NOTICE -
DYNAMIC GAS THERMOMETRY
E. W. Hagen
Instrumentation and Controls Division
This resort was prepared as an account of Coronament sponsored work. Noluber the Unilad
Suter, mor the Commission, sor my person acua on behalf of the Coa miontan:
A. Make. any warriaty or reproseatation, expres.md or imaidd, win roopert the accu.
racy, completenes., or wwetulber, of the laformation contained in to report, or that there wa.
of any lalor malina, apparatus, wethod. or proces. (klound ta wo report may not fairinge
princely owad righto; or
8. Aonme un Itabiliter will respect to the une of, or lor damu.. ro.wun from the
uw of any information, apparstus, molbod, or mocare disclosed la We report.
Ao und in the abovs, "person octag on behalf of the Commisolon" include, nay m.
ployee or contractor of the Comminolas, or employee of such contractor, to the extent that
auch employs or cont'actor of the Compiuloa, or employs of anxa contractor preparer,
disseminates, o provides acc... to. any informuoa pinnat to do employ mat os' codiraci
with the Commusloa, or Al, employment mul sub contractor,
A study of dynamic gas thermometry utilizing small throated, sonic
flow nozzles for making in-reactor high-temperature measurements and for
application to cther high-temperature measuring problems has been under
investigation at ORNL. The study was begun when application of a
pneumatic themperature-measuring (PTM) system was proposed for the EGCR.
By this method, space temperatures are determined from the predictable
temperature-pressure relation of a gas flowing at sonic velocity through
two nozzles in series. The investigation is directed toward developing
a general-purpose temperature measuring system that will be unaffected
by prolonged exposure to temperatures in excess of 1000 F or to radio-
activity.
If a practical system is to be developed, stable nozzle-flow per-
formance is required; therefore, nozzles made from selected materials
to determine their long-term stability and accuracy in the
ORNL Experimental Gas-Cooled Reactor (EGCR) and the feasibility of using
very small nozzles (approx 0.010-in. throat) for other temperature
measuring problems. Since a slight change in the physical character-
istics of small nozzles can appreciably alter the flow calibration, the
effects of simulated EGCR gas conditions, without the abrasive constit-
uents, were investigated. Extended time tests on three nozzles fabri-
cated from types 304 and 321 stainless steels and from Inconel were
conducted. Nozzle calibrations are shown in rig. 20.1 where 100 hr of
continuous testing is the equivalent of a minimum of 2.65 yr of cyclic
operation in the EGCR. In each case, a shift in the value of the flow
coefficient was noted at a second calibration after 150 hr of high-
temperature operation. This shift was apparently caused by changes in
the material which altered the nozzle geometry and the dynamics of the
gas-to-surface boundary conditions. Because of this phenomenon, PTM
nozzles are preaged or conditioned for a minimum of 150 hr before final
calibration and after they have been installed into probes.
OINI - AEC - OFFICIAL
Three other nozzles were tested for flow-coefficient stability by
thermally cycling them from 200 to 1200°F (rise time of 10 min, holding
time at 1200F for 5 min, cooling time of 20 min) and by exposing them
to sonic flow velocities in a helium atmosphere at temperatures from
1000 to 1600°F for extended periods of time. Two of the nozzles were
made from type 304 stainless steel, since nozzles made of this material
will be used in the EGCR-PTM system. As expected, the smallest nozzle
showed the largest percentage change in flow coefficient, and the largest
nozzle showed the smallest change (Table 20.1). Only the total change
in value of Plow coefficient is shown, because neither the elapsed time
for each test nor the time between calibration checks was the same for
these tests.
ORNI - AIC - OFFICIAL
MATENI CLEARATICI. OR1236. First To
THE PUBLIC IS APPROVED. PROR:1805
ARE ON FILE IN THE RECE.11716 SECNON.
IV1110-IV - INTO
WIJI:10 - ) IV - INVO
ORNL-LR - DWG 75050
C, FLOW COEFFICIENT = ACTUAL FLOW
RATE/THEORETICAL FLOW RATE
INITIAL CALIBRATION
150 hr CALIBRATION
500 hr CALIBRATION
0.99



304 STAINLESS STEEL
(0.0232-in. NOZZLE),
095 1321 STAINLESS STEEL
(0.019-in. NOZZLE)
098 LINCONEL (0.020-in. NOZZLE).
0.98
0.97
C, FLOW COEFFICIENT
C, FLOW COEFFICIENT
C, FLOW COEFFICIENT
20.2
0.96
0.95
EGCR PTM
OPERATING
RANGE
EGCR PTM
OPERATING
RANGE
EGCR PTM.
OPERATING |
RANGE
0.95
0.94
6
8 105
104
6
8 109
108
6
4
REYNOLDS NO.
8 105
4
REYNOLDS NO.
4
REYNOLDS NO.
Fig. 20.1. PTM Nozzles-Flow Coefficient Stability.
ORMI - AIC - OISICIAL
ORNI - AIC - OFFICIAL
ORNI - AEC - OFFICIAL
ORNI - TIC-OITicTÃO
20.3
Table 20.1.
Change in Flow Coefficients of Nozzles After
Thermal Cycling and Sonic Flow
Throat Number of Hours in
Diameter Thermal Sonic
(in.) Cycles Flow
Change in
Coefficient,
Nozzle
Number
Material
0.005
20
50
-25
109
Type 304
stainless steel
Type 304
stainless steel
Chromium Carbide
0.0115
195
62
-8.1
150
0.023
82
393
-2.0
Unlike earlier reported tests on nozzle material stability, the
shape of the flow-coefficient curve did not change during these test runs.
However, changes were caused by welding and brazing the nozzles into
sections of test loop tubing (Fig. 20.2).
An investigation was begun to explore the applicability of the
relatively inexpensive cemented carbides to PTM. Small nozzles were
made in samples of tungsten-carbide with a cobalt binder and in chromium-
carbide with a nickel binder. Development of a satisfactory mounting
technique remains the principal problem. Brazing with either copper or
a nickel-palladium alloy into stainless steel holders has not produced
an acceptable bond. Microscopic examinations revealed small cracks in
the carbide nozzles, probably caused by differential expansion between
the stainless steel holder and the carbide materials.
ing the nozzle first into & collar of a metal having an inter-
mediate coefficient of thermal expansion has produced promising results.
A chromium-carbide nozzle was pressed-fitted into a copper ring, and the
unit was pressed into a type 304 stainless steel holder having the same
wall thickness as that of the copper ring. This assembly was then copper
brazed. Repeated cycling in an argon atmosphere from 200 to 1200 °F pro-
duced no evidence of leakage, nozzle cracking, or deformation of the
nozzles.
ORNI - AEC - OFFICIAL
-carbide nozzles were operated from 200 to 1500°F with
a maximum deviation of 0.5% after 1000 hr. An inadvertent furnace
temperature excursion to 1700 °F caused the nozzles to deform. TWO
chromium-carbide nozzles have been substituted and are being initial.ly
tested at 1000°F. For temperatures below 1600°F, these cemented
materials may find satisfactory use in radiation environments, but
higher temperatures will cause a reorientation of the granular particles
in the material and result in a changed nozzle flow calibration.
While sapphire appears to be a desirable material, its leak-tight
mounting into an appropriate high-temperature metal holder presents a
problem. Also, from other work, the flow performance for small sapphire
ORNI - AC - OFFICIAL
W.91110-51051NO:
UNCLASSIFIED
ORNL-DWG 63-2402


CHROMIUM CARBIDE
(0.023-in. NOZZLE)
C, FLOW COEFFICIENT
C,FLOW COEFFICIENT
20.4
304 STAINLESS STEEL
(0.0115-in. NOZZLE)
44 UNMOUNTED NOZZLE
2 AFTER BRAZING OR
WELDING
3 AFTER THERMAL CYCLING
14 AFTER SONIC FLOW
• TESTING
.
· 0.80
104
. 2 4 6x104
REYNOLDS NO.
104
2 4 6x104
REYNOLDS NO.
Fig. 20.2. Stability of Flow Coefficients for Stainless Steel and
Chromium Carbide Nozzles.
ORNI - AIC - OFFICIAL
ONNI - AIC - OIFICIAL
ORNI - Atvorniciar
20.5
orifices was found to change when thermally cycled. However, these
their performance for long-time (months) flow measurement is unknown.
A temperature measuring system utilizing miniature nozzles,
0.0025. and 0.005-in. throat diameter and made from type 304 stainless
steel welded into 1/8-in. stainless steel tubing, has successfully
measured furnace temperatures up to 1600°F. Although the repeatability
of the system was within 0.1%, the ratio of the computed temperature
obtained from the system to the actual furnace temperature was not
constant. It varied linearly with the high temperature. This discrep-
ancy was traced to a change in the effective throat area of the hot
nozzle caused by material instability and partial plugging by foreign
particles.
A practical lower limit of 0.015 in. was found for nozzle throat
diameters during the stability testing of nozzle flow coefficients.
Smaller diameters are too prone to plug, and slight changes in the
throat cross-sectional area cause great changes in nozzle calibration;
hence, there are large indicated temperature errors in the measuring
unit. Therefore, the practicability of pneumatic temperature measure-
ments utilizing sonic flow nozzles remains dependent on finding a
suitable high-temperature nozzle material.
In cooperation with the EGCR-PTM program, a life test on a one-
third-scale nozzle was conducted in an environment simulating reactor
operating conditions of pressure, temperature, and gas composition.
The nozzle flow coefficient was checked and monitored throughout
1300 hr of continuous testing, which is the equivalent of 17.8 yr of
service in the proposed PTM system. At this constant temperature of
1050 F, the flow coefficient stabilized within 150 hr, and the final
value differed from the initial value by 0.75%; variations after the
first 150 hr were not discernible. The change of 0.75% amounts to
an error of +25°F .
The requirements for studying the stability of EGCR-PTM nozzles
were determined and a closed-loop test facility was constructed
(Fig. 20.3). The test loop simulates PTM flow conditions during EGCR
operation with the exception of radiation and solid particulates in
the gas stream. Essentially, the test nozzles are soaked in the
reactor helium gas mixture at 300 psia and 1030°F and are subjected to
sonic flow through the throat for 15 sec once every 10 min. The
nozzles tested in this loop are fabricated from Inconel and from type
304 stainless steel, nitrided. The latter are typical of those to
be installed into the EGCR Periodically the nozzles are removed from
and calivreted. Any change in the value for the flow
coefficient from the initial pretest value is attributed to a change
in the nozzle throat geometry and is expressed as a cemperature error
in the PTM system (Fig. 20.4). Life testing is being continued, and
ORNE AEC - OFFICIAL
ORNI - AIC - OFFICIAL
have not stabilized. Based on a calibration after 512 days, the error
W11110 - IV - INTO
T
10-3V-INIO
UNCLASSIFIED
ORNL-OWG 64-5607

PRESSURE
RELIEF
COMPRESSOR
SHUT-DOWN
CIRCUIT
PREHEATER
POWER SUPPLY
TEST FURNACE
SUPPLY
PRESSURE
SWITCH
PRESSURE
SWITCH
TEMPERATURE
CONTROLLER
TEMPERATURE
CONTROLLER
TEMPERATURE
SWITCH
TEMPERATURE
SWITCH
20.6
NOZZLE UPSTREAM
PRESSURE
REGULATOR
UIT
WATER
HYDRANT
NOZZLE TEST
FURNACE
GAS PREHEATER
TO DRAIN
CYCLE
TIMER
AIR
HYDRANT
ATMOSPHERE
VENT
HIGH PRESSURE
ACCUMULATORS
DIAPHRAGM
COMPRESSOR
LOW PRESSURE
DUMP TANKS
MAKE-UP
GAS CYLINDER
ORNI - AC-OISICIAL
ORNL-AIC - OFFICIAL
รมะ - พะ๐
NO. C3180. 1o DIVISIONS M'EN INOM DOIM WAYS 10 X 100 DIVISIONS,
PRIMILO IH U.S.A. ON (ILARINI 11.6.
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TEMPERATURE TERROR TEJE
WOOD
DUAL CURVES: SHOW THE TO
AND BOTTOM RESPECTIVELY.
OP! THE EGCR PIM
OPERATING RANGE
..
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antype
20.7
-
100 1120 1140 160 180 200 220 240 260 280 100. 320.349. 360
SIMULATED EGCA TM. OPERATION : TEST: :2002 TIME DAYS..
-
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EMPERATURE ERROR
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Gotta HHHH NOTESEE ABOVE NOTA
HILD
I LLIDHEIT
20.40:11601180 1700 1120:140: 160 180 200 220 240 260 280 300 320 340 360
DI SIMULATEDILEGRIPIMORERATION - ZEST|400P TIME, DRYS. :
ORNI -AIC - OFFICIAL
Fig. 20.4. Stability of WGCR-PTM Nozzle Flow Coefficient.
ORNI AIC - OLNICIAL
Lochained initiatedniided nimesidad donddabbuinidin
-anak and audu
9XNL - AEC - OFFICIAL
ORNI-MIC-OINICIAL
20.8
in the PTM system due to the coefficient drift to date would be from
+85 to +104 °F for the low and the high portions of the PTM range,
respectively. At present, the drift rate appears to be decreasing in
both test nozzles, but this may be due to cresting of another cycle
(Fig. 20.4).
ORNE - AEC - OFFICIAL
ORNI - AC - OFFICIAL
DATE FILMED
| 5 / 14 / 65







SL
VALERY
TITAN
iti
:
.
..
.
- LEGAL NOTICE

This report was prepared as an account of Government sponsorert work. Neither the United
States, nor the Commission, nor any person acting on behalf of the Commission:
A. Makes any warranty or representation, expressed or implied, with respect to the accu-
racy, completeness, or usefulness of the information contained in this report, or that the use
of any information, apparatus, method, or process disclosed in this report may not Infringe
privately owned rights; or
B. Assumes any liabilities with respect to the use of, or for damages resulting from the
use of any information, apparatus, method, or process disclosed in this report,
As used in the above, "person acting on behalf of the Commission" includes any em-
ployee or contractor of the Commission, or employee of such contractor, to the extent that
such employee or contractor of the Commission, or employee of such contractor prepares,
disseminates, or provides access to, any information pursuant to his employment or contract
with the Commission, or his employment with such contractor.
L
!
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TA
END
t.
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