ASTM E744-07(2015)
(Practice)Standard Practice for Evaluating Solar Absorptive Materials for Thermal Applications
Standard Practice for Evaluating Solar Absorptive Materials for Thermal Applications
SIGNIFICANCE AND USE
4.1 The methods in this practice are intended to aid in the assessment of long-term performance by comparative testing of absorptive materials. The results of the methods, however, have not been shown to correlate to actual in-service performance.
4.2 The testing methodology in this practice provides two testing methods, in accordance with Fig. 1.
4.2.1 Method A, which aims at decreasing the time required for evaluation, uses a series of individual tests to simulate various exposure conditions.
4.2.2 Method B utilizes a single test of actual outdoor exposure under conditions simulating thermal stagnation.
4.2.3 Equivalency of the two methods has not yet been established.
SCOPE
1.1 This practice covers a testing methodology for evaluating absorptive materials used in flat plate or concentrating collectors, with concentrating ratios not to exceed five, for solar thermal applications. This practice is not intended to be used for the evaluation of absorptive surfaces that are (1) used in direct contact with, or suspended in, a heat-transfer liquid, (that is, trickle collectors, direct absorption fluids, etc.); (2) used in evacuated collectors; or (3) used in collectors without cover plate(s).
1.2 Test methods included in this practice are property measurement tests and aging tests. Property measurement tests provide for the determination of various properties of absorptive materials, for example, absorptance, emittance, and appearance. Aging tests provide for exposure of absorptive materials to environments that may induce changes in the properties of test specimens. Measuring properties before and after an aging test provides a means of determining the effect of the exposure.
1.3 The assumption is made that solar radiation, elevated temperature, temperature cycles, and moisture are the primary factors that cause degradation of absorptive materials. Aging tests are described for exposure of specimens to these factors.
Note 1: For some geographic locations, other factors, such as salt spray and dust erosion, may be important. They are not evaluated by this practice.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 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: E744 − 07 (Reapproved 2015)
Standard Practice for
Evaluating Solar Absorptive Materials for Thermal
1
Applications
This standard is issued under the fixed designation E744; 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 ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This practice covers a testing methodology for evaluat-
mendations issued by the World Trade Organization Technical
ing absorptive materials used in flat plate or concentrating
Barriers to Trade (TBT) Committee.
collectors, with concentrating ratios not to exceed five, for
solar thermal applications. This practice is not intended to be
2. Referenced Documents
used for the evaluation of absorptive surfaces that are (1) used
2
in direct contact with, or suspended in, a heat-transfer liquid,
2.1 ASTM Standards:
(that is, trickle collectors, direct absorption fluids, etc.); (2)
B537Practice for Rating of Electroplated Panels Subjected
used in evacuated collectors; or (3) used in collectors without
to Atmospheric Exposure
cover plate(s).
E408Test Methods for Total Normal Emittance of Surfaces
Using Inspection-Meter Techniques
1.2 Test methods included in this practice are property
measurement tests and aging tests. Property measurement tests E434Test Method for Calorimetric Determination of Hemi-
spherical Emittance and the Ratio of SolarAbsorptance to
provide for the determination of various properties of absorp-
tive materials, for example, absorptance, emittance, and ap- Hemispherical Emittance Using Solar Simulation
E772Terminology of Solar Energy Conversion
pearance. Aging tests provide for exposure of absorptive
materials to environments that may induce changes in the E781Practice for Evaluating Absorptive Solar Receiver
properties of test specimens. Measuring properties before and Materials When Exposed to Conditions Simulating Stag-
after an aging test provides a means of determining the effect nation in Solar Collectors With Cover Plates
of the exposure. E903Test Method for Solar Absorptance, Reflectance, and
Transmittance of Materials Using Integrating Spheres
1.3 The assumption is made that solar radiation, elevated
G26 Practice for Operating Light-Exposure Apparatus
temperature, temperature cycles, and moisture are the primary
(Xenon-Arc Type) With and Without Water for Exposure
factors that cause degradation of absorptive materials. Aging
of Nonmetallic Materials (Discontinued 2001) (With-
tests are described for exposure of specimens to these factors.
3
drawn 2000)
NOTE 1—For some geographic locations, other factors, such as salt
G90Practice for Performing Accelerated Outdoor Weather-
spray and dust erosion, may be important. They are not evaluated by this
ing of Materials Using Concentrated Natural Sunlight
practice.
G151PracticeforExposingNonmetallicMaterialsinAccel-
1.4 The values stated in SI units are to be regarded as the
erated Test Devices that Use Laboratory Light Sources
standard.
G155PracticeforOperatingXenonArcLampApparatusfor
1.5 This standard does not purport to address all of the
Exposure of Materials
safety concerns, if any, associated with its use. It is the
NOTE 2—In previous editions, G26 was referenced for xenon arc
responsibility of the user of this standard to establish appro-
exposure. It has been replaced with Practices G151 and G155, the
priate safety, health, and environmental practices and deter-
performance based standards, which cover the same apparatus used in
mine the applicability of regulatory limitations prior to use.
Practice G26. The latter had described very specific designs used for
xenon arc exposure.
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1 2
This practice is under the jurisdiction of ASTM Committee E44 on Solar, For referenced ASTM standards, visit the ASTM website, www.astm.org, or
GeothermalandOtherAlternativeEnergySourcesandisthedirectresponsibilityof contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Subcommittee E44.20 on Optical Materials for Solar Applications. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved March 1, 2015. Published April 2015. Discontinued the ASTM website.
3
February 2002 and reinstated as E744–07. Last previous edition approved in 2007 The last approved version of this historical standard is referenced on
as E744–07. DOI: 10.1520/E0744-07R15. www.astm.org.
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...
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: E744 − 07 E744 − 07 (Reapproved 2015)
Standard Practice for
Evaluating Solar Absorptive Materials for Thermal
1
Applications
This standard is issued under the fixed designation E744; 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 practice covers a testing methodology for evaluating absorptive materials used in flat plate or concentrating collectors,
with concentrating ratios not to exceed five, for solar thermal applications. This practice is not intended to be used for the
evaluation of absorptive surfaces that are (1) used in direct contact with, or suspended in, a heat-transfer liquid, (that is, trickle
collectors, direct absorption fluids, etc.); (2) used in evacuated collectors; or (3) used in collectors without cover plate(s).
1.2 Test methods included in this practice are property measurement tests and aging tests. Property measurement tests provide
for the determination of various properties of absorptive materials, for example, absorptance, emittance, and appearance. Aging
tests provide for exposure of absorptive materials to environments that may induce changes in the properties of test specimens.
Measuring properties before and after an aging test provides a means of determining the effect of the exposure.
1.3 The assumption is made that solar radiation, elevated temperature, temperature cycles, and moisture are the primary factors
that cause degradation of absorptive materials. Aging tests are described for exposure of specimens to these factors.
NOTE 1—For some geographic locations, other factors, such as salt spray and dust erosion, may be important. They are not evaluated by this practice.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 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
2.1 ASTM Standards:
B537 Practice for Rating of Electroplated Panels Subjected to Atmospheric Exposure
E408 Test Methods for Total Normal Emittance of Surfaces Using Inspection-Meter Techniques
E434 Test Method for Calorimetric Determination of Hemispherical Emittance and the Ratio of Solar Absorptance to
Hemispherical Emittance Using Solar Simulation
E772 Terminology of Solar Energy Conversion
E781 Practice for Evaluating Absorptive Solar Receiver Materials When Exposed to Conditions Simulating Stagnation in Solar
Collectors With Cover Plates
E903 Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres
G26 Practice for Operating Light-Exposure Apparatus (Xenon-Arc Type) With and Without Water for Exposure of Nonmetallic
3
Materials (Discontinued 2001) (Withdrawn 2000)
G90 Practice for Performing Accelerated Outdoor Weathering of Nonmetallic Materials Using Concentrated Natural Sunlight
G151 Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
G155 Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
NOTE 2—In previous editions, G26 was referenced for xenon arc exposure. It has been replaced with Practices G151 and G155, the performance based
standards, which cover the same apparatus used in Practice G26. The latter had described very specific designs used for xenon arc exposure.
1
This practice is under the jurisdiction of ASTM Committee E44 on Solar, Geothermal and Other Alternative Energy Sources and is the direct responsibility of
Subcommittee E44.05 on Solar Heating and Cooling Systems and Materials.
Current edition approved July 1, 2007March 1, 2015. Published August 2007April 2015. Discontinued February 2002 and reinstated as E744-07. Last previous edition
approved in 19962007 as E744-85(1996).E744-07. DOI: 10.1520/E0744-07.10.1520/E0744-07R15.
2
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.
3
The last approved version of this historical standard is referenced on www.astm.org.
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