ASTM E422-05(2016)
(Test Method)Standard Test Method for Measuring Heat Flux Using a Water-Cooled Calorimeter
Standard Test Method for Measuring Heat Flux Using a Water-Cooled Calorimeter
SIGNIFICANCE AND USE
4.1 The purpose of this test method is to measure the heat flux to a water-cooled surface for purposes of calibration of the thermal environment into which test specimens are placed for evaluation. If the calorimeter and holder size, shape, and surface finish are identical to that of the test specimen, the measured heat flux to the calorimeter is presumed to be the same as that to the sample's heated surface. The measured heat flux is one of the important parameters for correlating the behavior of materials.
4.2 The water-cooled calorimeter is one of several calorimeter concepts used to measure heat flux. The prime drawback is its long response time, that is, the time required to achieve steady-state operation. To calculate energy added to the coolant water, accurate measurements of the rise in coolant temperature are needed, all energy losses should be minimized, and steady-state conditions must exist both in the thermal environment and fluid flow of the calorimeter.
4.3 Regardless of the source of energy input to the water-cooled calorimeter surface (radiative, convective, or combinations thereof) the measurement is averaged over the surface active area of the calorimeter. If the water-cooled calorimeter is used to measure only radiative flux or combined convective-radiative heat-flux rates, then the surface reflectivity of the calorimeter shall be measured over the wavelength region of interest (depending on the source of radiant energy). If nonuniformities exist in the gas stream, a large surface area water-cooled calorimeter would tend to smooth or average any variations. Consequently, it is advisable that the size of the calorimeter be limited to relatively small surface areas and applied to where the heat-flux is uniform. Where large samples are tested it is recommended that a number of smaller diameter water-cooled calorimeters be used (rather than one large unit). These shall be located across the heated surface such that a heat-flux distribution can ...
SCOPE
1.1 This test method covers the measurement of a steady heat flux to a given water-cooled surface by means of a system energy balance.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E422 − 05 (Reapproved 2016)
Standard Test Method for
Measuring Heat Flux Using a Water-Cooled Calorimeter
This standard is issued under the fixed designation E422; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1. The water-cooled annular guard ring serves the purpose of
preventing heat transfer to the sides of the calorimeter and
1.1 This test method covers the measurement of a steady
establishes flat-plate flow. An energy balance on the system
heatfluxtoagivenwater-cooledsurfacebymeansofasystem
(the centrally located calorimeter in Fig. 1) requires that the
energy balance.
energy crossing the sensing surface (A,in Fig. 1)ofthe
1.2 The values stated in SI units are to be regarded as
calorimeter be equated to the energy absorbed by the calorim-
standard. No other units of measurement are included in this
eter cooling water. Interpretation of the data obtained is not
standard.
within the scope of this discussion; consequently, such effects
1.3 This standard does not purport to address all of the
as recombination efficiency of the surface and thermochemical
safety concerns, if any, associated with its use. It is the state of the boundary layer are outside the scope of this test
responsibility of the user of this standard to establish appro-
method. It should be noted that recombination effects at low
priate safety and health practices and determine the applica- pressurescancauseseriousdiscrepanciesinheatfluxmeasure-
bility of regulatory limitations prior to use.
ments (such as discussed in Ref (1)) depending upon the
surface material on the calorimeter.
2. Referenced Documents
3.3 For the particular control volume cited, the energy
2.1 ASTM Standards:
balance can be written as follows:
E235Specification for Thermocouples, Sheathed, Type K
E 5 mC ∆T 2∆T /A (1)
@ ~ !#
CAL p 0 1
and Type N, for Nuclear or for Other High-Reliability
Applications where:
−2
E = energy flux transferred to calorimeter face, W·m
CAL
3. Summary of Test Method −1
m = mass flow rate of coolant water, kg·s
−1 −1
C = water specific heat, J·kg ·K ,
3.1 A measure of the heat flux to a given water-cooled
p
∆T = T —T calorimeter water bulk temperature rise
surface is based upon the following measurements: (1)the
0 0 0
2 1
during operation, K,
water mass flow rate and (2)the temperature rise of coolant
∆T = T —T =calorimeter water apparent bulk tempera-
water. The heat flux is determined numerically by multiplying 1 2 1
ture rise before operation, K,
the water coolant flow rate by the specific heat and rise in
T = water exhaust bulk temperature during operation, K,
temperature of the water and dividing this value by the surface 0
T = water inlet bulk temperature during operation, K,
area across which heat has been transferred. 1
T = water exhaust bulk temperature before operation, K,
3.2 The apparatus for measuring heat flux by the energy-
T = water inlet bulk temperature before operation, K,
balance technique is illustrated schematically in Fig. 1.Itisa
and
typical constant-flow water calorimeter used to measure stag-
A = sensing surface area of calorimeter, m .
nation region heat flux to a flat-faced specimen. Other calo-
3.4 An examination of Eq 1 shows that to obtain a value of
rimeter shapes can also be easily used. The heat flux is
the energy transferred to the calorimeter, measurements must
measuredusingthecentralcircularsensingarea,showninFig.
be made of the water coolant flow rate, the temperature rise of
the coolant, and the surface area across which heat is trans-
1 ferred. With regard to the latter quantity it is assumed that the
This test method is under the jurisdiction of ASTM Committee E21 on Space
Simulation andApplications of SpaceTechnology and is the direct responsibility of
surface area to which heat is transferred is well defined. As is
Subcommittee E21.08 on Thermal Protection.
indicatedinFig.1,thedesignofthecalorimeterissuchthatthe
Current edition approved April 1, 2016. Published April 2016. Originally
heat transfer area is confined by design to the front or directly
approved in 1971. Last previous edition approved in 2011 as E422–05(2011).
heated surface. To minimize side heating or side heat losses, a
DOI: 10.1520/E0422-05R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
the ASTM website. this test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E422 − 05 (2016)
FIG. 1 Steady-State Water-Cooled Calorimeter.
water-cooled guard ring or shroud is utilized and is separated radiative heat-flux rates, then the surface reflectivity of the
physicallyfromthecalorimeterbymeansofanairgapandlow calorimeter shall be measured over the wavelength region of
conductivity bushing such as nylon. The air gap is recom- interest (depending on the source of radiant energy). If non-
mended to be no more than 0.5 mm on the radius. Thus, if
uniformities exist in the gas stream, a large surface area
severe pressure variations exist across the face of the
water-cooled calorimeter would tend to smooth or average any
calorimeter, side heating caused by flow into and out of the air
variations. Consequently, it is advisable that the size of the
gap will be minimized. Also, since the water-cooled calorim-
calorimeter be limited to relatively small surface areas and
eter and guard ring operate at low surface temperatures
appliedtowheretheheat-fluxisuniform.Wherelargesamples
(usually lower than 100°C) heat losses across the gap by
aretesteditisrecommendedthatanumberofsmallerdiameter
radiant interchange are negligible and consequently no special
water-cooled calorimeters be used (rather than one large unit).
calorimetersurfacegapfinishesarenecessary.Dependingupon
These shall be located across the heated surface such that a
the size of the calorimeter surface, large variations in heat flux
heat-flux distribution can be described. With this, a more
may exist across the face of the calorimeter. Consequently, the
detailed heat-flux measurement can be applied to the specimen
measured heat flux represents an average heat flux over the
test and more information can be deduced from the test.
surface area of the water-cooled calorimeter.The water-cooled
calorimeter can be used to measure heat-flux levels over a
5. Apparatus
2 2
range from 10 kW/m to 60 MW/m .
5.1 General—The apparatus shall consist of a water-cooled
4. Significance and Use
calorimeter and the necessary instrumentation to measure the
heat transferred to the calorimeter.Although the recommended
4.1 The purpose of this test method is to measure the heat
instrumentation accuracies are state-of-the-art values, more
fluxtoawater-cooledsurfaceforpurposesofcalibrationofthe
rugged and higher accuracy instrumentation may be required
thermal environment into which test specimens are placed for
for high pressure and high heat-flux applications.Anumber of
evaluation. If the calorimeter and holder size, shape, and
materials can be used to fabricate the calorimeter, but OFHC
surface finish are identical to that of the test specimen, the
(oxygen free high conductivity) copper is often preferred
measured heat flux to the calorimeter is presumed to be the
because of its superior thermal properties.
sameasthattothesample’sheatedsurface.Themeasuredheat
flux is one of the important parameters for correlating the
5.2 Coolant Flow Measurement—The water flow rate to
behavior of materials.
each component of the calorimeter shall be chosen to cool the
4.2 The water-cooled calorimeter is one of several calorim-
apparatus adequately and to ensure accurately measurable rise
eterconceptsusedtomeasureheatflux.Theprimedrawbackis
inwatertemperature.Theerrorinwaterflowratemeasurement
its long response time, that is, the time required to achieve
shall be not more than 62%. Suitable equipment that can be
steady-stateoperation.Tocalculateenergyaddedtothecoolant
used is listed in Ref (2) and includes turbine flowmeters,
water, accurate measurements of the rise in coolant tempera-
variableareaflowmeters,etc.Caremustbeexercisedintheuse
ture are needed, all energy losses should be minimized, and
of all these devices. In particular, it is recommended that
steady-state conditions must exist both in the thermal environ-
appropriate filters be placed in all water inlet lines to prevent
ment and fluid flow of the calorimeter.
particles or unnecessary deposits from being carried to the
water-coolingpassages,pipe,andmeterwalls.Waterflowrates
4.3 Regardless of the source of energy input to the water-
and pressure shall be adjusted to ensure that no bubbles are
cooled calorimeter surface (radiative, convective, or combina-
tions thereof) the measurement is averaged over the surface formed (no boiling). If practical, the water flowmeters shall be
placed upstream of the calorimeter in straight portions of the
activeareaofthecalorimeter.Ifthewater-cooledcalorimeteris
used to measure only radiative flux or combined convective- piping. The flowmeter device shall be checked and calibrated
E422 − 05 (2016)
periodically. Pressure gages, if required, shall be used in 6. Procedure
accordance with the manufacturer’s instructions and calibra-
6.1 It is essential that the environment be at steady-state
tion charts.
conditions prior to testing if the water-cooled calorimeter is to
5.3 Coolant Temperature Measurement—The method of give a representative measure of the heat flux.
temperature measurement must be sufficiently sensitive and
6.2 After a sufficient length of time has elapsed to assure
reliable to ensure accurate measurement of the coolant water
constantmassflowofwateraswellasconstantinletandoutlet
temperature rise. Procedures similar to those given in Specifi-
water temperature, place the system into the heat-source
cation E235, Type K, and Ref (3) should be followed in the
environment. Steady-state operation has been assured if the
calibrationandpreparationoftemperaturesensors.Thebulkor
inlet and exhaust water temperature, and water flow rates are
average temperature of the coolant shall be measured at the
steadyandnotchangingwithtime.Inparticularthewaterflow
inlet and outlet lines of each cooled unit. The error in
rates should not change during operation. After removing the
measurement of temperature difference between inlet and
calorimeter from the environment, record the inlet water
outlet shall be not more than 61%. The water temperature
temperature and flow rates so that they can be compared with
indicating devices shall be placed as close as practical to the
pretest values. Changes between pre- and post-test water
calorimeter’s heated surface in the inlet and outlet lines.
temperature rise may indicate deposit buildups on the calorim-
However, care must be exercised so as not to place the
eterbackfaceorcoolingpassageswhichmayaltertheresultsof
temperature sensors where there is energy exchange between
the measurement of energy transfer.
the incoming (cold) water and the outgoing (heated) water.
6.3 To ensure consistent heat-flux data, it is recommended
Thisoccursmostreadilyatflowdividersandatthecalorimeter
that measurements be repeated with the same apparatus. A
sensing surface. No additional apparatus shall be placed in the
further check on the measurement of heat flux using a
line between the temperature sensor and the heat source. The
water-cooledcalorimeterwouldbetouseadifferentmassflow
temperature measurements shall be recorded continuously to
of water through the calorimeter for different test runs. No
verifythatsteady-stateoperationhasbeenachieved.Reference
significant difference in heat-flux measurements should be
(2) lists a variety of commercially available temperature
noted with the change in water flow rate for different test runs.
sensors. Temperature sensors which are applicable include
liquid-in-glass thermometers, thermopiles, thermocouples, and
7. Heat-Flux Calculation
thermistors.Duringoperationoftheheatsource,careshouldbe
7.1 The quantities as defined by Eq 1 shall be calculated
taken to minimize deposits on the temperature sensors and to
based on the bulk or average temperature rise of the coolant
eliminateanypossibilityofsensorheatingbecauseofspecimen
water for each water-cooled section of the calorimeter. The
radiation to the sensor. In addition, all water lines should be
choiceofunitsshallbeconsistentwiththemeasuredquantities.
shielded from direct-flow impingement or radiation from the
test environment.
7.2 Variance analyses of heat-source conditions shall pro-
5.3.1 Ifatallpracticalathermocoupleshallbeplacedonthe
vide a sound basis for estimation of the reproducibility of the
water-cooled side of the heated calorimeter surface. Although
thermal environment. Refs (4) and (5) may provide a basis for
this surface temperature (water side) measurement is not used
error analysis of the measurements.
directly in the calculation of heat flux it is necessary for the
8. Report
calculation of the surface temperature (front face) used in the
correction of the measured heat flux to walls of different
8.1 In reporting the results of the measurement tests, the
temperatures.
following steady-state data shall be reported:
8.1.1 Dimensions of the calorimeter configuration active
5.4 Recording Means:
surface and guard ring,
5.4.1 Sincemeasurementoftheenergytransferrequiresthat
8.1.2 Calorimeter coolant water flow rate,
thecalorimeteroperateasasteadystatedevice,allcalculations
8.1.3 Temperature rise of calorimeter coolant water,
will use only measurements taken after it has been established
8.1.4 Calculated heat flux,
that the device has achieved steady operating levels. To assure
8.1.5 Front surface temperature (if measured or calculated),
steady flow or operating conditions the above mentioned
and
parameters shall be continuously recorded such that instanta-
8.1.6 Variance of results.
neous measurements are available to establish a measure of
steady-state operation.Wherever possible it is highly desirable
9. Measurement Uncertainty
that the differential temperature (∆T) be made of the desired
parameters rather than absolute measurements. 9.1 There are a number of methods that can be used for the
5.4.2 In all cases, parameters of interest, such as water flow determination of measurement uncertainty. A recent summary
rates and co
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E422 − 05 (Reapproved 2011) E422 − 05 (Reapproved 2016)
Standard Test Method for
Measuring Heat Flux Using a Water-Cooled Calorimeter
This standard is issued under the fixed designation E422; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the measurement of a steady heat flux to a given water-cooled surface by means of a system energy
balance.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
E235 Specification for Thermocouples, Sheathed, Type K and Type N, for Nuclear or for Other High-Reliability Applications
3. Summary of Test Method
3.1 A measure of the heat flux to a given water-cooled surface is based upon the following measurements: (1) the water mass
flow rate and (2) the temperature rise of coolant water. The heat flux is determined numerically by multiplying the water coolant
flow rate by the specific heat and rise in temperature of the water and dividing this value by the surface area across which heat
has been transferred.
3.2 The apparatus for measuring heat flux by the energy-balance technique is illustrated schematically in Fig. 1. It is a typical
constant-flow water calorimeter used to measure stagnation region heat flux to a flat-faced specimen. Other calorimeter shapes can
also be easily used. The heat flux is measured using the central circular sensing area, shown in Fig. 1. The water-cooled annular
guard ring serves the purpose of preventing heat transfer to the sides of the calorimeter and establishes flat-plate flow. An energy
balance on the system (the centrally located calorimeter in Fig. 1) requires that the energy crossing the sensing surface (A, in Fig.
1) of the calorimeter be equated to the energy absorbed by the calorimeter cooling water. Interpretation of the data obtained is not
within the scope of this discussion; consequently, such effects as recombination efficiency of the surface and thermochemical state
of the boundary layer are outside the scope of this test method. It should be noted that recombination effects at low pressures can
cause serious discrepancies in heat flux measurements (such as discussed in Ref (1)) depending upon the surface material on the
calorimeter.
3.3 For the particular control volume cited, the energy balance can be written as follows:
E 5 @mC ~ΔT 2 ΔT !#/A (1)
CAL p 0 1
where:
−2
E = energy flux transferred to calorimeter face, W·m
CAL
−1
m = mass flow rate of coolant water, kg·s
−1 −1
C = water specific heat, J·kg ·K ,
p
ΔT = T — T calorimeter water bulk temperature rise during operation, K,
0 0 0
2 1
ΔT = T — T = calorimeter water apparent bulk temperature rise before operation, K,
1 2 1
This test method is under the jurisdiction of ASTM Committee E21 on Space Simulation and Applications of Space Technology and is the direct responsibility of
Subcommittee E21.08 on Thermal Protection.
Current edition approved Oct. 1, 2011April 1, 2016. Published April 2012April 2016. Originally approved in 1971. Last previous edition approved in 20052011 as
E422E422 – 05 (2011). – 05. DOI: 10.1520/E0422-05R11.10.1520/E0422-05R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The boldface numbers in parentheses refer to the list of references at the end of this test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E422 − 05 (2016)
FIG. 1 Steady-State Water-Cooled Calorimeter.
T = water exhaust bulk temperature during operation, K,
T = water inlet bulk temperature during operation, K,
T = water exhaust bulk temperature before operation, K,
T = water inlet bulk temperature before operation, K, and
A = sensing surface area of calorimeter, m .
3.4 An examination of Eq 1 shows that to obtain a value of the energy transferred to the calorimeter, measurements must be
made of the water coolant flow rate, the temperature rise of the coolant, and the surface area across which heat is transferred. With
regard to the latter quantity it is assumed that the surface area to which heat is transferred is well defined. As is indicated in Fig.
1, the design of the calorimeter is such that the heat transfer area is confined by design to the front or directly heated surface. To
minimize side heating or side heat losses, a water-cooled guard ring or shroud is utilized and is separated physically from the
calorimeter by means of an air gap and low conductivity bushing such as nylon. The air gap is recommended to be no more than
0.5 mm on the radius. Thus, if severe pressure variations exist across the face of the calorimeter, side heating caused by flow into
and out of the air gap will be minimized. Also, since the water-cooled calorimeter and guard ring operate at low surface
temperatures (usually lower than 100°C) heat losses across the gap by radiant interchange are negligible and consequently no
special calorimeter surface gap finishes are necessary. Depending upon the size of the calorimeter surface, large variations in heat
flux may exist across the face of the calorimeter. Consequently, the measured heat flux represents an average heat flux over the
surface area of the water-cooled calorimeter. The water-cooled calorimeter can be used to measure heat-flux levels over a range
2 2
from 10 kW/m to 60 MW/m .
4. Significance and Use
4.1 The purpose of this test method is to measure the heat flux to a water-cooled surface for purposes of calibration of the
thermal environment into which test specimens are placed for evaluation. If the calorimeter and holder size, shape, and surface
finish are identical to that of the test specimen, the measured heat flux to the calorimeter is presumed to be the same as that to the
sample’s heated surface. The measured heat flux is one of the important parameters for correlating the behavior of materials.
4.2 The water-cooled calorimeter is one of several calorimeter concepts used to measure heat flux. The prime drawback is its
long response time, that is, the time required to achieve steady-state operation. To calculate energy added to the coolant water,
accurate measurements of the rise in coolant temperature are needed, all energy losses should be minimized, and steady-state
conditions must exist both in the thermal environment and fluid flow of the calorimeter.
4.3 Regardless of the source of energy input to the water-cooled calorimeter surface (radiative, convective, or combinations
thereof) the measurement is averaged over the surface active area of the calorimeter. If the water-cooled calorimeter is used to
measure only radiative flux or combined convective-radiative heat-flux rates, then the surface reflectivity of the calorimeter shall
be measured over the wavelength region of interest (depending on the source of radiant energy). If nonuniformities exist in the
gas stream, a large surface area water-cooled calorimeter would tend to smooth or average any variations. Consequently, it is
advisable that the size of the calorimeter be limited to relatively small surface areas and applied to where the heat-flux is uniform.
Where large samples are tested it is recommended that a number of smaller diameter water-cooled calorimeters be used (rather than
one large unit). These shall be located across the heated surface such that a heat-flux distribution can be described. With this, a
more detailed heat-flux measurement can be applied to the specimen test and more information can be deduced from the test.
5. Apparatus
5.1 General—The apparatus shall consist of a water-cooled calorimeter and the necessary instrumentation to measure the heat
transferred to the calorimeter. Although the recommended instrumentation accuracies are state-of-the-art values, more rugged and
E422 − 05 (2016)
higher accuracy instrumentation may be required for high pressure and high heat-flux applications. A number of materials can be
used to fabricate the calorimeter, but OFHC (oxygen free high conductivity) copper is often preferred because of its superior
thermal properties.
5.2 Coolant Flow Measurement—The water flow rate to each component of the calorimeter shall be chosen to cool the apparatus
adequately and to ensure accurately measurable rise in water temperature. The error in water flow rate measurement shall be not
more than 62 %. Suitable equipment that can be used is listed in Ref (2) and includes turbine flowmeters, variable area flowmeters,
etc. Care must be exercised in the use of all these devices. In particular, it is recommended that appropriate filters be placed in all
water inlet lines to prevent particles or unnecessary deposits from being carried to the water-cooling passages, pipe, and meter
walls. Water flow rates and pressure shall be adjusted to ensure that no bubbles are formed (no boiling). If practical, the water
flowmeters shall be placed upstream of the calorimeter in straight portions of the piping. The flowmeter device shall be checked
and calibrated periodically. Pressure gages, if required, shall be used in accordance with the manufacturer’s instructions and
calibration charts.
5.3 Coolant Temperature Measurement—The method of temperature measurement must be sufficiently sensitive and reliable to
ensure accurate measurement of the coolant water temperature rise. Procedures similar to those given in Specification E235, Type
K, and Ref (3) should be followed in the calibration and preparation of temperature sensors. The bulk or average temperature of
the coolant shall be measured at the inlet and outlet lines of each cooled unit. The error in measurement of temperature difference
between inlet and outlet shall be not more than 61 %. The water temperature indicating devices shall be placed as close as practical
to the calorimeter’s heated surface in the inlet and outlet lines. However, care must be exercised so as not to place the temperature
sensors where there is energy exchange between the incoming (cold) water and the outgoing (heated) water. This occurs most
readily at flow dividers and at the calorimeter sensing surface. No additional apparatus shall be placed in the line between the
temperature sensor and the heat source. The temperature measurements shall be recorded continuously to verify that steady-state
operation has been achieved. Reference (2) lists a variety of commercially available temperature sensors. Temperature sensors
which are applicable include liquid-in-glass thermometers, thermopiles, thermocouples, and thermistors. During operation of the
heat source, care should be taken to minimize deposits on the temperature sensors and to eliminate any possibility of sensor heating
because of specimen radiation to the sensor. In addition, all water lines should be shielded from direct-flow impingement or
radiation from the test environment.
5.3.1 If at all practical a thermocouple shall be placed on the water-cooled side of the heated calorimeter surface. Although this
surface temperature (water side) measurement is not used directly in the calculation of heat flux it is necessary for the calculation
of the surface temperature (front face) used in the correction of the measured heat flux to walls of different temperatures.
5.4 Recording Means:
5.4.1 Since measurement of the energy transfer requires that the calorimeter operate as a steady state device, all calculations
will use only measurements taken after it has been established that the device has achieved steady operating levels. To assure
steady flow or operating conditions the above mentioned parameters shall be continuously recorded such that instantaneous
measurements are available to establish a measure of steady-state operation. Wherever possible it is highly desirable that the
differential temperature (ΔT) be made of the desired parameters rather than absolute measurements.
5.4.2 In all cases, parameters of interest, such as water flow rates and cooling water temperature rises should be automatically
recorded throughout the measurement period. Recording speed or sampling frequency will depend on the variations of the
parameters being recorded. When a strip chart recorder is used, the response time of the recorder shall be 1 s or less for full-scale
deflection. Timing marks should be an integral part of the recorder with a minimum requirement of 1/s.
6. Procedure
6.1 It is essential that the environment be at steady-state conditions prior to testing if the water-cooled calorimeter is to give
a representative measure of the heat flux.
6.2 After a sufficient length of time has elapsed to assure constant mass flow of water as well as constant inlet and outlet water
temperature, place the system into the heat-source environment. Steady-state operation has been assured if the inlet and exhaust
water temperature, and water flow rates are steady and not changing with time. In particular the water flow rates should not change
during operation. After removing the calorimeter from the environment, record the inlet water temperature and flow rates so that
they can be compared with pretest values. Changes between pre- and post-test water temperature rise may indicate deposit buildups
on the calorimeter backface or cooling passages which may alter the results of the measurement of energy transfer.
6.3 To ensure consistent heat-flux data, it is recommended that measurements be repeated with the same apparatus. A further
check on the measurement of heat flux using a water-cooled calorimeter would be to use a different mass flow of water through
the calorimeter for different test runs. No significant difference in heat-flux measurements should be noted with the change in water
flow rate for different test runs.
7. Heat
...
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