ASTM E457-08
(Test Method)Standard Test Method for Measuring Heat-Transfer Rate Using a Thermal Capacitance (Slug) Calorimeter
Standard Test Method for Measuring Heat-Transfer Rate Using a Thermal Capacitance (Slug) Calorimeter
SIGNIFICANCE AND USE
The purpose of this test method is to measure the rate of thermal energy per unit area transferred into a known piece of material (slug) for purposes of calibrating the thermal environment into which test specimens are placed for evaluation. The calorimeter and holder size and shape should be identical to that of the test specimen. In this manner, the measured heat transfer rate to the calorimeter can be related to that experienced by the test specimen.
The slug calorimeter is one of many calorimeter concepts used to measure heat transfer rate. This type of calorimeter is simple to fabricate, inexpensive, and readily installed since it is not water-cooled. The primary disadvantages are its short lifetime and relatively long cool-down time after exposure to the thermal environment. In measuring the heat transfer rate to the calorimeter, accurate measurement of the rate of rise in back-face temperature is imperative.
In the evaluation of high-temperature materials, slug calorimeters are used to measure the heat transfer rate on various parts of the instrumented models, since heat transfer rate is one of the important parameters in evaluating the performance of ablative materials.
Regardless of the source of thermal energy to the calorimeter (radiative, convective, or a combination thereof) the measurement is averaged over the calorimeter surface. If a significant percentage of the total thermal energy is radiative, consideration should be given to the emissivity of the slug surface. If non-uniformities exist in the input energy, the heat transfer rate calorimeter would tend to average these variations; therefore, the size of the sensing element (that is, the slug) should be limited to small diameters in order to measure local heat transfer rate values. Where large ablative samples are to be tested, it is recommended that a number of calorimeters be incorporated in the body of the test specimen such that a heat transfer rate distribution across the heated surface...
SCOPE
1.1 This test method describes the measurement of heat transfer rate using a thermal capacitance-type calorimeter which assumes one-dimensional heat conduction into a cylindrical piece of material (slug) with known physical properties.
1.2 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.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
Note 1—For information see Test Methods E 285, E 422, E 458, E 459, and E 511.
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Designation: E457 − 08
StandardTest Method for
Measuring Heat-Transfer Rate Using a Thermal Capacitance
1
(Slug) Calorimeter
This standard is issued under the fixed designation E457; 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 3.1.1 Density and specific heat of the slug material,
3.1.2 Length or axial distance from the front face of the
1.1 This test method describes the measurement of heat
cylindrical slug to the back-face thermocouple,
transfer rate using a thermal capacitance-type calorimeter
3.1.3 Slope of the temperature—time curve generated by
which assumes one-dimensional heat conduction into a cylin-
the back-face thermocouple, and
drical piece of material (slug) with known physical properties.
3.1.4 Calorimeter temperature history.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.2 The heat transfer rate is thus determined numerically by
responsibility of the user of this standard to establish appro-
multiplyingthedensity,specificheat,andlengthoftheslugby
priate safety and health practices and determine the applica-
the slope of the temperature–time curve obtained by the data
bility of regulatory limitations prior to use.
acquisition system (see Eq 1).
1.3 The values stated in SI units are to be regarded as
3.3 The technique for measuring heat transfer rate by the
standard. No other units of measurement are included in this
thermal capacitance method is illustrated schematically in Fig.
standard.
1.Theapparatusshownisatypicalslugcalorimeterwhich,for
NOTE 1—For information see Test Methods E285, E422, E458, E459,
example, can be used to determine both stagnation region heat
and E511.
transfer rate and side-wall or afterbody heat transfer rate
values.Theannularinsulatorservesthepurposeofminimizing
2. Referenced Documents
heat transfer to or from the body of the calorimeter, thus
2
2.1 ASTM Standards:
approximating one-dimensional heat flow. The body of the
E285Test Method for Oxyacetylene Ablation Testing of
calorimeter is configured to establish flow and should have the
Thermal Insulation Materials
same size and shape as that used for ablation models or test
E422Test Method for Measuring Heat Flux Using a Water-
specimens.
Cooled Calorimeter
3.3.1 For the control volume specified in this test method, a
E458Test Method for Heat of Ablation
thermal energy balance during the period of initial linear
E459Test Method for Measuring Heat Transfer Rate Using
temperatureresponsewhereheatlossesareassumednegligible
a Thin-Skin Calorimeter
can be stated as follows:
E511TestMethodforMeasuringHeatFluxUsingaCopper-
EnergyReceivedbytheCalorimeter ~frontface!
Constantan Circular Foil, Heat-Flux Transducer
5EnergyConductedAxiallyIntotheSlug
3. Summary of Test Method
q 5 ρC l ∆T/∆τ 5 MC /A ∆T/∆τ (1)
~ ! ~ !~ !
c p p
3.1 The measurement of heat transfer rate to a slug or
where:
thermal capacitance type calorimeter may be determined from
2
q˙ = calorimeter heat transfer rate, W/m ,
c
the following data:
3
ρ = density of slug material, kg/m ,
C = average specific heat of slug material during the
p
1
temperature rise (∆T), J/kg·K,
This test method is under the jurisdiction of ASTM Committee E21 on Space
Simulation andApplications of SpaceTechnology and is the direct responsibility of
l = length or axial distance from front face of slug to the
Subcommittee E21.08 on Thermal Protection.
thermocouple location (back-face), m,
Current edition approved May 1, 2008. Published June 2008. Originally
∆T =(T − T)=calorimeter slug temperature rise during
f i
approved in 1972. Last previous edition approved in 2002 as E457–96(2002).
exposure to heat source (linear part of curve), K,
DOI: 10.1520/E0457-08.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or ∆τ =(τ −τ)=time period corresponding to ∆T tempera-
f i
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ture rise, s,
Standards volume information, refer to the standard’s Document Summary page on
M = mass of the cylindrical slug, kg,
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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E457 − 08
2
A = cross-sectional area of slug, m .
1
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E457 − 08
FIG. 1 Schematic of a Thermal Capacitance (Slug) Calorimeter
In order to determine the steady-state heat transfer rate with possible decaying processes such as a drop in surface
athermalcapacitance-typecalorimeter,E
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:E457–96 (Reapproved 2002) Designation: E 457 – 08
Standard Test Method for
Measuring Heat-Transfer Rate Using a Thermal Capacitance
1
(Slug) Calorimeter
This standard is issued under the fixed designation E457; 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
1.1 This test method describes the measurement of heat transfer rate using a thermal capacitance-type calorimeter which
assumes one-dimensional heat conduction into a cylindrical piece of material (slug) with known physical properties.
1.2 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.
1.3The values stated in SI units are to be regarded as the standard.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
NOTE 1—For information see Test Methods E285, E422, E458, E459, and E511.
2. Referenced Documents
2
2.1 ASTM Standards:
E285 Test Method for Oxyacetylene Ablation Testing of Thermal Insulation Materials
E422 Test Method for Measuring Heat Flux Using a Water-Cooled Calorimeter
E458 Test Method for Heat of Ablation
E459 Test Method for Measuring Heat Transfer Rate Using a Thin-Skin Calorimeter
2
E511 Test Method for Measuring Heat Flux Using a Copper-Constantan Circular Foil, Heat-Flux Gage Transducer
3. Summary of Test Method
3.1 The measurement of heat transfer rate to a slug or thermal capacitance type calorimeter may be determined from the
following data:
3.1.1 Density and specific heat of the slug material,
3.1.2 Length or axial distance from the front face of the cylindrical slug to the back-face thermocouple,
3.1.3 Slope of the temperature—time curve generated by the back-face thermocouple, and
3.1.4 Calorimeter temperature history.
3.2 The heat transfer rate is thus determined numerically by multiplying the density, specific heat, and length of the slug by the
slope of the temperature–time curve obtained by the data acquisition system (see Eq 1).
3.3 The technique for measuring heat transfer rate by the thermal capacitance method is illustrated schematically in Fig. 1.The
apparatus shown is a typical slug calorimeter which, for example, can be used to determine both stagnation region heat transfer
rate and side-wall or afterbody heat transfer rate values. The annular insulator serves the purpose of minimizing heat transfer to
or from the body of the calorimeter, thus approximating one-dimensional heat flow. The body of the calorimeter is configured to
establish flow and should have the same size and shape as that used for ablation models or test specimens.
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.
1
Current edition approved May 10, 2002. Published December 1996. Originally published as E457–72. Last previous edition E457–72(1990)´ .
Current edition approved May 1, 2008. Published June 2008. Originally approved in 1972. Last previous edition approved in 2002 as E457–96(2002).
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book of ASTM Standards
, Vol 15.03.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
E457–08
FIG. 1 Schematic of a Thermal Capacitance (Slug) Calorimeter
3.3.1 For the control volume specified in this test method, a thermal energy balance during the period of initial linear
temperature response where heat losses are assumed negligible can be stated as follows:
EnergyReceivedbytheCalorimeter ~frontface! (1)
5EnergyConductedAxiallyIntotheSlug
q 5rC l ~DT/Dt! 5 ~MC /A! ~DT/Dt!
c p p
where:
2
q˙ = calorimeter heat transfer rate, W/m ,
c
3
r = density of slug material, kg/m ,
C = average specific heat of slug material during the temperature rise (DT), J/kg·K,
p
l = length or axial distance from front
...
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