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ASTM E434-71(2002)

(Test Method)

Standard Test Method for Calorimetric Determination of Hemispherical Emittance and the Ratio of Solar Absorptance to Hemispherical Emittance Using Solar Simulation

Standard Test Method for Calorimetric Determination of Hemispherical Emittance and the Ratio of Solar Absorptance to Hemispherical Emittance Using Solar Simulation

ABSTRACT
This test method covers measurement techniques for calorimetrically determining the ratio of solar absorptance to hemispherical emittance using a steady-state method, and for calorimetrically determining the total hemispherical emittance using a transient technique. The main elements of the apparatus include a vacuum system, a cold shroud within the vacuum chamber, instrumentation for temperature measurement, and a solar simulator. Any type of coating may be tested by this test method provided its structure remains stable in vacuum over the temperature range of interest. The substrate shall be machined from flat stock and to a size proportioned to the working area of the chamber.
SCOPE
1.1 This test method covers measurement techniques for calorimetrically determining the ratio of solar absorptance to hemispherical emittance using a steady-state method, and for calorimetrically determining the total hemispherical emittance using a transient technique.
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.

General Information

Status
Historical
Publication Date
20-Jun-1971
ICS
27.160 - Solar energy engineering
Technical Committee
E21 - Space Simulation and Applications of Space Technology
Drafting Committee
E21.04 - Space Simulation Test Methods
Current Stage
Ref Project

Relations

Replaces
ASTM E434-71(1996)e1 - Standard Test Method for Calorimetric Determination of Hemispherical Emittance and the Ratio of Solar Absorptance to Hemispherical Emittance Using Solar Simulation
Effective Date
21-Jun-1971
Replaced By
ASTM E434-10 - Standard Test Method for Calorimetric Determination of Hemispherical Emittance and the Ratio of Solar Absorptance to Hemispherical Emittance Using Solar Simulation
Effective Date
01-Nov-2010
Referred By
ASTM E781-86(2023) - Standard Practice for Evaluating Absorptive Solar Receiver Materials When Exposed to Conditions Simulating Stagnation in Solar Collectors with Cover Plates
Effective Date
21-Jun-1971
Referred By
ASTM E512-94(2020) - Standard Practice for Combined, Simulated Space Environment Testing of Thermal Control Materials with Electromagnetic and Particulate Radiation
Effective Date
21-Jun-1971
Referred By
ASTM E744-07(2022) - Standard Practice for Evaluating Solar Absorptive Materials for Thermal Applications
Effective Date
21-Jun-1971

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ASTM E434-71(2002) - Standard Test Method for Calorimetric Determination of Hemispherical Emittance and the Ratio of Solar Absorptance to Hemispherical Emittance Using Solar SimulationASTM E434-71(2002) - Standard Test Method for Calorimetric Determination of Hemispherical Emittance and the Ratio of Solar Absorptance to Hemispherical Emittance Using Solar Simulation
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ASTM E434-71(2002) - Standard Test Method for Calorimetric Determination of Hemispherical Emittance and the Ratio of Solar Absorptance to Hemispherical Emittance Using Solar Simulation
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:E434–71 (Reapproved 2002)
Standard Test Method for
Calorimetric Determination of Hemispherical Emittance and
the Ratio of Solar Absorptance to Hemispherical Emittance
1
Using Solar Simulation
This standard is issued under the fixed designation E434; 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 deformation under vacuum conditions. The radiant energy
absorbedbythespecimenfromthesolarsourceandemittedby
1.1 This test method covers measurement techniques for
the specimen to the surroundings cause the specimen to reach
calorimetrically determining the ratio of solar absorptance to
anequilibriumtemperaturethatisdependentuponthe a/´ratio
hemispherical emittance using a steady-state method, and for
of its surface.
calorimetrically determining the total hemispherical emittance
3.3 In the dynamic radiative method of measuring total
using a transient technique.
hemispherical emittance, the specimen is heated with a solar
1.2 This standard does not purport to address all of the
simulation source and then allowed to cool by radiation to an
safety concerns, if any, associated with its use. It is the
evacuated space chamber with an inside effective emittance of
responsibility of the user of this standard to establish appro-
unity.Fromaknowledgeofthespecificheatofthespecimenas
priate safety and health practices and determine the applica-
a function of temperature, the area of the test specimen, its
bility of regulatory limitations prior to use.
mass,itscoolingrate,andthetemperatureofthewalls,itstotal
2. Referenced Documents
hemispherical emittance may be calculated as a function of
2
temperature.
2.1 ASTM Standards:
E349 Terminology Relating to Space Simulation
4. Apparatus
3. Summary of Test Method 4.1 The main elements of the apparatus include a vacuum
system, a cold shroud within the vacuum chamber, instrumen-
3.1 In calorimetric measurements of the radiative properties
tation for temperature measurement, and a solar simulator.
of materials, the specimen under evaluation is placed in a
4.2 Theareaofthethermalshroudshallnotbelessthan100
vacuumenvironmentundersimulatedsolarradiationwithcold
timesthespecimenarea(controlledbythespecimensize).The
surroundings. By observation of the thermal behavior of the
inner surfaces of the chamber shall have a high solar absorp-
specimen the thermophysical properties may be determined by
tance (not less than 0.96) and a total hemispherical emittance
an equation that relates heat balance considerations to measur-
3
of at least 0.88 (painted with a suitable black paint), and shall
able test parameters.
be diffuse. Suitable insulated standoffs shall be provided for
3.2 Inatypicalmeasurement,todetermine a/´asdefinedin
suspending the specimen. Thermocouple wires shall be con-
Definitions E349, the side of the specimen in question is
nected to a vacuumtight fitting where the temperature of
exposed to a simulated solar source, through a port having
feedthrough is uniform. Outside of the chamber, all thermo-
suitable transmittance over the solar spectrum. This port, or
couples shall connect with a fixed cold junction.
window, must be of sufficient diameter that the specimen and
4.3 The chamber shall be evacuated to a pressure of
radiation monitor will be fully irradiated and must be of
−6
1 310 torr (0.1 mPa) or less at all times.
sufficient thickness that it will maintain its strength without
4.4 The walls of the inner shroud shall be in contact with
coolant so that their temperature can be maintained uniform at
1
This test method is under the jurisdiction of ASTM Committee E21 on Space all times.
Simulation andApplications of SpaceTechnology and is the direct responsibility of
4.5 A shutter shall be provided in one end of the chamber
Subcommittee E21.04 on Space Simulation Test Methods.
which can be opened to admit a beam of radiant energy from
Current edition approved April 10, 2002. Published April 2002. Originally
a solar simulator. When open, this shutter shall provide an
approved in 1971. Last previous edition approved in 1996 as E434–71 (1996).
DOI: 10.1520/E0434-71R02.
apertureadmittingthefullsimulatorbeam.Whentheshutteris
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
3
Standards volume information, refer to the standard’s Document Summary page on Nextel Brand Velvet Coating 401-C10 Black, available from Reflective
the ASTM website. Products Div., 3M Co., has been found to be satisfactory.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West C
...

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Standard Test Method for Calorimetric Determination of Hemispherical Emittance and the Ratio of Solar Absorptance to Hemispherical Emittance Using Solar Simulation

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This test method covers measurement techniques for calorimetrically determining the ratio of solar absorptance to hemispherical emittance using a steady-state method, and for calorimetrically determining the total hemispherical emittance using a transient technique. The main elements of the apparatus include a vacuum system, a cold shroud within the vacuum chamber, instrumentation for temperature measurement, and a solar simulator. Any type of coating may be tested by this test method provided its structure remains stable in vacuum over the temperature range of interest. The substrate shall be machined from flat stock and to a size proportioned to the working area of the chamber.
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5.1 Because there are a number of choices in this test method that depend on different applications and system configurations, it is the responsibility of the user of this test method to specify the details and protocol of an individual system power measurement prior to the beginning of a measurement.  
5.2 Unlike device-level measurements that report performance at a fixed device temperature of 25 °C, such as Test Methods E1036, this test method uses regression to a reference ambient air temperature.  
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1.3.2 Testing of individual photovoltaic modules or systems for comparison to other photovoltaic modules or systems, and  
1.3.3 Testing of photovoltaic systems for the purpose of comparing the performance of photovoltaic systems located in different places.  
1.4 In this test method, photovoltaic system power is reported with respect to a set of reporting conditions (RC) including solar irradiance in the plane of the modules, ambient temperature, and wind speed (see Section 6). Measurements under a variety of reporting conditions are allowed to facilitate testing and comparison of results.  
1.5 This test method assumes that the solar cell temperature is directly influenced by ambient temperature and wind speed; if not the regression results may be less meaningful.  
1.6 The capacity measured according to this test method should not be used to make representations about the energy generation capabilities of the system.  
1.7 This test method is not applicable to concentrator photovoltaic systems; as an alternative, Test Method E2527 should be considered for such systems.  
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2.2 This practice describes a standard procedure for mounting the test specimen, conducting the impact test, and reporting the effects.  
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1.6.2 Mounted on a separate test frame cover plate holder (Type 2 specimen).  
1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.8 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
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4.2 This practice is intended as a screening test for absorber materials and coatings. All conditions are chosen to be representative of those encountered in solar collectors with single cover plates and with no added means of limiting the temperature during stagnation conditions.  
4.3 This practice uses exposure in a simulated collector with a single cover plate. Although collectors with additional cover plates will produce higher temperatures at stagnation, this procedure is considered to provide adequate thermal testing for most applications.
Note 1: Mathematical modeling has shown that a selective absorber, single glazed flat-plate solar collector can attain absorber plate stagnation temperatures as high as 226 °C (437 °F) with an ambient temperature of 37.8 °C (100 °F) and zero wind velocity, and a double glazed one as high as 245 °C (482 °F) under these conditions. The same configuration solar collector with a nonselective absorber can attain absorber stagnation temperatures as high as 146 °C (284 °F) if single glazed, and 185 °C (360 °F) if double glazed, with the same environmental conditions (see “Performance Criteria for Solar Heating and Cooling Systems in Commercial Buildings,” NBS Technical Note 1187).4  
4.4 This practice evaluates the thermal stability of absorber materials. It does not evaluate the moisture stability of absorber materials used in actual solar collectors exposed outdoors. Moisture intrusion into solar collectors is a frequent occurrence in addition to condensation caused by diurnal breathing.  
4.5 This practice differentiates between the testing of spectrally selective absorbers and nonselective absorbers.  
4.5.1 Testing Spectrally Selective...
SCOPE
1.1 This practice covers a test procedure for evaluating absorptive solar receiver materials and coatings when exposed to sunlight under cover plate(s) for long durations. This practice is intended to evaluate the exposure resistance of absorber materials and coatings used in flat-plate collectors where maximum non-operational stagnation temperatures will be approximately 200 °C (392 °F).  
1.2 This practice shall not apply to receiver materials used in solar collectors without covers (unglazed) or in evacuated collectors, that is, those that use a vacuum to suppress convective and conductive thermal losses.  
1.3 The values stated in SI units are to be regarded as the standard.  
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, health, and environmental 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.

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ASTM
ASTM E816-15(2023)(Test Method)
Standard Test Method for Calibration of Pyrheliometers by Comparison to Reference Pyrheliometers

SIGNIFICANCE AND USE
4.1 Though the sun trackers employed, the number of instantaneous readings, and the data acquisition equipment used will vary from instrument to instrument and from laboratory to laboratory, this test method provides for the minimum acceptable conditions, procedures, and techniques required.  
4.2 While the greatest accuracy will be obtained when calibrating pyrheliometers with a self-calibrating absolute cavity pyrheliometer that has been demonstrated by intercomparison to be within ±0.5 % of the mean irradiance of a family of similar absolute instruments, acceptable accuracy can be achieved by careful attention to the requirements of this test method when transferring calibration from a secondary reference to a field pyrheliometer.  
4.3 By meeting the requirements of this test method, traceability of calibration to the World Radiometric Reference (WRR) can be achieved through one or more of the following recognized intercomparisons:  
4.3.1 International Pyrheliometric Comparison (IPC) VII, Davos, Switzerland, held in 1990, and every five years thereafter, and the PMO-2 absolute cavity pyrheliometer that is the primary reference instrument of WMO.6  
4.3.2 Any WMO-sanctioned intercomparison of self-calibrating absolute cavity pyrheliometers held in WMO Region IV (North and Central America).  
4.3.3 Any sanctioned or non-sanctioned intercomparison held in the United States the purpose of which is to transfer the WRR from the primary reference absolute cavity pyrheliometer maintained as the primary reference standard of the United States by the National Oceanic and Atmospheric Administration's Solar Radiation Facility in Boulder, CO.7  
4.3.4 Any future intercomparisons of comparable reference quality in which at least one self-calibrating absolute cavity pyrheliometer is present that participated in IPC VII or a subsequent IPC, and in which that pyrheliometer is treated as the intercomparison's reference instrument.  
4.3.5 Any of the absolute radiometers p...
SCOPE
1.1 This test method has been harmonized with, and is technically equivalent to, ISO 9059.  
1.2 Two types of calibrations are covered by this test method. One is the calibration of a secondary reference pyrheliometer using an absolute cavity pyrheliometer as the primary standard pyrheliometer, and the other is the transfer of calibration from a secondary reference to one or more field pyrheliometers. This test method prescribes the calibration procedures and the calibration hierarchy, or traceability, for transfer of the calibrations.
Note 1: It is not uncommon, and is indeed desirable, for both the reference and field pyrheliometers to be of the same manufacturer and model designation.  
1.3 This test method is relevant primarily for the calibration of reference pyrheliometers with field angles of 5° to 6°, using as the primary reference instrument a self-calibrating absolute cavity pyrheliometer having field angles of about 5°. Pyrheliometers with field angles greater than 6.5° shall not be designated as reference pyrheliometers.  
1.4 When this test method is used to transfer calibration to field pyrheliometers having field angles both less than 5° or greater than 6.5°, it will be necessary to employ the procedure defined by Angstrom and Rodhe.2  
1.5 This test method requires that the spectral response of the absolute cavity chosen as the primary standard pyrheliometer be nonselective over the range from 0.3 μm to 10 μm wavelength. Both reference and field pyrheliometers covered by this test method shall be nonselective over a range from 0.3 μm to 4 μm wavelength.  
1.6 The primary and secondary reference pyrheliometers shall not be field instruments and their exposure to sunlight shall be limited to calibration or intercomparisons. These reference instruments shall be stored in an isolated cabinet or room equipped with standard laboratory temperature and humidity control.
Note 2: At a laboratory where cali...

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