ASTM E2684-17
(Test Method)Standard Test Method for Measuring Heat Flux Using Surface-Mounted One-Dimensional Flat Gages
Standard Test Method for Measuring Heat Flux Using Surface-Mounted One-Dimensional Flat Gages
SIGNIFICANCE AND USE
5.1 This test method will provide guidance for the measurement of the net heat flux to or from a surface location. To determine the radiant energy component the emissivity or absorptivity of the gage surface coating is required and should be matched with the surrounding surface. The potential physical and thermal disruptions of the surface due to the presence of the gage should be minimized and characterized. For the case of convection and low source temperature radiation to or from the surface it is important to consider how the presence of the gage alters the surface heat flux. The desired quantity is usually the heat flux at the surface location without the presence of the gage.
5.1.1 Temperature limitations are determined by the gage material properties and the method of application to the surface. The range of heat flux that can be measured and the time response are limited by the gage design and construction details. Measurements from 10 W/m2 to above 100 kW/m2 are easily obtained with current sensors. Time constants as low as 10 ms are possible, while thicker sensors may have response times greater than 1 s. It is important to choose the sensor style and characteristics to match the range and time response of the required application.
5.2 The measured heat flux is based on one-dimensional analysis with a uniform heat flux over the surface of the gage surface. Because of the thermal disruption caused by the placement of the gage on the surface, this may not be true. Wesley (3) and Baba et al. (4) have analyzed the effect of the gage on the thermal field and heat transfer within the surface substrate and determined that the one-dimensional assumption is valid when:
where:
ks = the thermal conductivity of the substrate material, R = the effective radius of the gage, δ = the combined thickness, and k = the effective thermal conductivity of the gage and adhesive layers.
5.3 Measurements of convective heat flux are part...
SCOPE
1.1 This test method describes the measurement of the net heat flux normal to a surface using flat gages mounted onto the surface. Conduction heat flux is not the focus of this standard. Conduction applications related to insulation materials are covered by Test Method C518 and Practices C1041 and C1046. The sensors covered by this test method all use a measurement of the temperature difference between two parallel planes normal to the surface to determine the heat that is exchanged to or from the surface in keeping with Fourier’s Law. The gages operate by the same principles for heat transfer in either direction.
1.2 This test method is quite broad in its field of application, size and construction. Different sensor types are described in detail in later sections as examples of the general method for measuring heat flux from the temperature gradient normal to a surface (1).2 Applications include both radiation and convection heat transfer. The gages have broad application from aerospace to biomedical engineering with measurements ranging form 0.01 to 50 kW/m 2. The gages are usually square or rectangular and vary in size from 1 mm to 10 cm or more on a side. The thicknesses range from 0.05 to 3 mm.
1.3 The values stated in SI units are to be regarded as the standard. The values stated in parentheses are provided for information only.
1.4 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.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2684 − 17
Standard Test Method for
Measuring Heat Flux Using Surface-Mounted One-
1
Dimensional Flat Gages
This standard is issued under the fixed designation E2684; 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 Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.1 This test method describes the measurement of the net
Barriers to Trade (TBT) Committee.
heatfluxnormaltoasurfaceusingflatgagesmountedontothe
surface. Conduction heat flux is not the focus of this standard.
2. Referenced Documents
Conduction applications related to insulation materials are
2.1 ASTM Standards:
coveredbyTestMethodC518andPracticesC1041andC1046.
C518Test Method for Steady-State Thermal Transmission
The sensors covered by this test method all use a measurement
Properties by Means of the Heat Flow Meter Apparatus
of the temperature difference between two parallel planes
C1041Practice for In-Situ Measurements of Heat Flux in
normaltothesurfacetodeterminetheheatthatisexchangedto
Industrial Thermal Insulation Using Heat Flux Transduc-
or from the surface in keeping with Fourier’s Law. The gages
ers
operate by the same principles for heat transfer in either
C1046Practice for In-Situ Measurement of Heat Flux and
direction.
Temperature on Building Envelope Components
1.2 Thistestmethodisquitebroadinitsfieldofapplication,
C1130Practice for Calibrating Thin Heat Flux Transducers
size and construction. Different sensor types are described in
3. Terminology
detail in later sections as examples of the general method for
measuring heat flux from the temperature gradient normal to a
3.1 Definitions of Terms Specific to This Standard:
2
surface (1). Applications include both radiation and convec-
3.1.1 heat flux—the heat transfer per unit area, q, with units
2 2
tion heat transfer. The gages have broad application from
of W/m (Btu/ft -s). Heat transfer (or alternatively heat-
aerospace to biomedical engineering with measurements rang-
transfer rate) is the rate of thermal-energy movement across a
2
ing form 0.01 to 50 kW/m . The gages are usually square or
system boundary with units of watts (Btu/s). This usage is
rectangular and vary in size from 1 mm to 10 cm or more on
consistent with most heat-transfer books.
a side. The thicknesses range from 0.05 to 3 mm.
3.1.2 heat-transfer coeffıcient, (h)—an important parameter
2 2
1.3 The values stated in SI units are to be regarded as the
inconvectiveflowswithunitsofW/m -K(Btu/ft -s-F).Thisis
standard. The values stated in parentheses are provided for
defined in terms of the heat flux q as:
information only.
q
h 5 (1)
1.4 This standard does not purport to address all of the
∆T
safety concerns, if any, associated with its use. It is the
where ∆T is a prescribed temperature difference between the
responsibility of the user of this standard to establish appro- surface and the fluid. The resulting value of h is intended to
be only a function of the fluid flow and geometry, not the
priate safety and health practices and determine the applica-
temperature difference. If the surface temperature is non-
bility of regulatory limitations prior to use.
uniform or if there is more than a single fluid free stream
1.5 This international standard was developed in accor-
temperature, the proper definition of ∆ T may be difficult to
dance with internationally recognized principles on standard-
specify (2). It is always important to clearly define ∆T when
ization established in the Decision on Principles for the
calculating the heat-transfer coefficient.
3.1.3 surfaceemissivity,(ε)—theratiooftheemittedthermal
radiation from a surface to that of a blackbody at the same
1
This test method is under the jurisdiction of ASTM Committee E21 on Space
temperature.Surfacesareassumedtobegraybodieswherethe
Simulation andApplications of SpaceTechnology and is the direct responsibility of
Subcommittee E21.08 on Thermal Protection. emissivity is equal to the absorptivity.
Current edition approved Sept. 1, 2017. Published October 2017. Originally
approved in 2009. Last previous edition approved in 2009 as E2684–09. DOI: 4. Summary of Test Method
10.1520/E2684-17.
2
4.1 A schematic of the sensing technique is illustrated in
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this test method. Fig. 1. Temperature is measured on either side of a thermal
Copyright © ASTM International, 100 Ba
...
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: E2684 − 09 E2684 − 17
Standard Test Method for
Measuring Heat Flux Using Surface-Mounted One-
1
Dimensional Flat Gages
This standard is issued under the fixed designation E2684; 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 describes the measurement of the net heat flux normal to a surface using flat gages mounted onto the
surface. Conduction heat flux is not the focus of this standard. Conduction applications related to insulation materials are covered
by Test Method C518 and Practices C1041 and C1046. The sensors covered by this test method all use a measurement of the
temperature difference between two parallel planes normal to the surface to determine the heat that is exchanged to or from the
surface in keeping with Fourier’s Law. The gages operate by the same principles for heat transfer in either direction.
1.2 This test method is quite broad in its field of application, size and construction. Different sensor types are described in detail
2
in later sections as examples of the general method for measuring heat flux from the temperature gradient normal to a surface (1).
Applications include both radiation and convection heat transfer. The gages have broad application from aerospace to biomedical
2
engineering with measurements ranging form 0.01 to 50 kW/m . The gages are usually square or rectangular and vary in size from
1 mm to 10 cm or more on a side. The thicknesses range from 0.05 to 3 mm.
1.3 The values stated in SI units are to be regarded as the standard. The values stated in parentheses are provided for information
only.
1.4 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.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C518 Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus
C1041 Practice for In-Situ Measurements of Heat Flux in Industrial Thermal Insulation Using Heat Flux Transducers
C1046 Practice for In-Situ Measurement of Heat Flux and Temperature on Building Envelope Components
C1130 Practice for Calibrating Thin Heat Flux Transducers
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
2 2
3.1.1 heat flux—the heat transfer per unit area, q, with units of W/m (Btu/ft -s). Heat transfer (or alternatively heat-transfer
rate) is the rate of thermal-energy movement across a system boundary with units of watts (Btu/s). This usage is consistent with
most heat-transfer books.
2 2
3.1.2 heat-transfer coeffıcient, (h)—an important parameter in convective flows with units of W/m -K (Btu/ft -s-F). This is
defined in terms of the heat flux q as:
q
h 5 (1)
ΔT
where ΔT is a prescribed temperature difference between the surface and the fluid. The resulting value of h is intended to be
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 June 15, 2009Sept. 1, 2017. Published August 2009October 2017. Originally approved in 2009. Last previous edition approved in 2009 as
E2684–09. DOI: 10.1520/E2684-09.10.1520/E2684-17.
2
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
1
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E2684 − 17
only a function of the fluid flow and geometry, not the temperature difference. If the surface temperature is non-uniform or if
there is more than a single fluid free stream temperature, the proper definition of Δ T may be difficult to specify (2). It is al-
ways important to clearly define ΔT when calculating the he
...
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