ASTM C177-2019 Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus.pdf

1、Designation: C177 19Standard Test Method forSteady-State Heat Flux Measurements and ThermalTransmission Properties by Means of the Guarded-Hot-PlateApparatus1This standard is issued under the fixed designation C177; the number immediately following the designation indicates the year oforiginal adopt

2、ion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense

3、.1. Scope1.1 This test method establishes the criteria for the labora-tory measurement of the steady-state heat flux through flat,homogeneous specimen(s) when their surfaces are in contactwith solid, parallel boundaries held at constant temperaturesusing the guarded-hot-plate apparatus.1.2 The test

4、apparatus designed for this purpose is known asa guarded-hot-plate apparatus and is a primary (or absolute)method. This test method is comparable, but not identical, toISO 8302.1.3 This test method sets forth the general design require-ments necessary to construct and operate a satisfactoryguarded-h

5、ot-plate apparatus. It covers a wide variety of appa-ratus constructions, test conditions, and operating conditions.Detailed designs conforming to this test method are not givenbut must be developed within the constraints of the generalrequirements. Examples of analysis tools, concepts and proce-dur

6、es used in the design, construction, calibration and opera-tion of a guarded-hot-plate apparatus are given in Refs (1-41).21.4 This test method encompasses both the single-sided andthe double-sided modes of measurement. Both distributed andline source guarded heating plate designs are permitted. The

7、user should consult the standard practices on the single-sidedmode of operation, Practice C1044, and on the line sourceapparatus, Practice C1043, for further details on these heaterdesigns.1.5 The guarded-hot-plate apparatus can be operated witheither vertical or horizontal heat flow. The user is ca

8、utionedhowever, since the test results from the two orientations may bedifferent if convective heat flow occurs within the specimens.1.6 Although no definitive upper limit can be given for themagnitude of specimen conductance that is measurable on aguarded-hot-plate, for practical reasons the specim

9、en conduc-tance should be less than 16 W/(m2K).1.7 This test method is applicable to the measurement of awide variety of specimens, ranging from opaque solids toporous or transparent materials, and a wide range of environ-mental conditions including measurements conducted at ex-tremes of temperature

10、 and with various gases and pressures.1.8 Inhomogeneities normal to the heat flux direction, suchas layered structures, can be successfully evaluated using thistest method. However, testing specimens with inhomogeneitiesin the heat flux direction, such as an insulation system withthermal bridges, ca

11、n yield results that are location specific andshall not be attempted with this type of apparatus. See TestMethod C1363 for guidance in testing these systems.1.9 Calculations of thermal transmission properties basedupon measurements using this method shall be performed inconformance with Practice C10

12、45.1.10 In order to ensure the level of precision and accuracyexpected, persons applying this standard must possess aknowledge of the requirements of thermal measurements andtesting practice and of the practical application of heat transfertheory relating to thermal insulation materials and systems.

13、Detailed operating procedures, including design schematicsand electrical drawings, should be available for each apparatusto ensure that tests are in accordance with this test method. Inaddition, automated data collecting and handling systemsconnected to the apparatus must be verified as to theiraccu

14、racy. This can be done by calibration and inputting datasets, which have known results associated with them, intocomputer programs.1.11 It is not practical for a test method of this type toestablish details of design and construction and the proceduresto cover all contingencies that might offer diff

15、iculties to aperson without technical knowledge concerning theory of heatflow, temperature measurements and general testing practices.The user may also find it necessary, when repairing or1This test method is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsi

16、bility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Jan. 1, 2019. Published January 2019. Originallyapproved in 1942. Last previous edition approved in 2013 as C177 13. DOI:10.1520/C0177-19.2The boldface numbers given in parentheses refer to the list of references at theend

17、of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDev

18、elopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1modifying the apparatus, to become a designer or builder, orboth, on whom the demands for fundamental understandingand careful experimental technique ar

19、e even greater. Standard-ization of this test method is not intended to restrict in any waythe future development of new or improved apparatus orprocedures.1.12 This test method does not specify all details necessaryfor the operation of the apparatus. Decisions on sampling,specimen selection, precon

20、ditioning, specimen mounting andpositioning, the choice of test conditions, and the evaluation oftest data shall follow applicable ASTM Test Methods, Guides,Practices or Product Specifications or governmental regula-tions. If no applicable standard exists, sound engineeringjudgment that reflects acc

21、epted heat transfer principles must beused and documented.1.13 This test method allows a wide range of apparatusdesign and design accuracy to be used in order to satisfy therequirements of specific measurement problems. Compliancewith this test method requires a statement of the uncertainty ofeach r

22、eported variable in the report. A discussion of thesignificant error factors involved is included.1.14 Major sections within this test method are arranged asfollows:Section SectionScope 1Referenced Documents 2Terminology 3Summary of Test Method 4Significance and Use 5Apparatus 6Specimen Preparation

23、and Conditioning 7Procedure 8Calculation of Results 9Report 10Precision and Bias 11Keywords 12FiguresGeneral Arrangement of the Mechanical Components of the Guarded-Hot-Plate ApparatusFig. 1Illustration of Heat Flow in the Guarded-Hot-Plate Apparatus Fig.2Example Report Form Fig. 3AnnexesImportance

24、of Thickness A1.1Measuring Thickness A1.2Limitations Due to Apparatus A1.3Limitations Due to Temperature A1.4Limitations Due to Specimen A1.5Random and Systematic Error Components A1.6Error Components for Variables A1.7Thermal Conductance or Thermal Resistance Error Analysis A1.8Thermal Conductivity

25、 or Thermal Resistivity Error Analysis A1.9Uncertainty Verification A1.101.15 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.16 This standard does not purport to address all of thesafety concerns, if any, associated with its

26、use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific precautionary statements are given in Note 22.1.17 This international standard was develope

27、d in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documen

28、ts2.1 ASTM Standards:3C168 Terminology Relating to Thermal InsulationC518 Test Method for Steady-State Thermal TransmissionProperties by Means of the Heat Flow Meter ApparatusC687 Practice for Determination of Thermal Resistance ofLoose-Fill Building InsulationC1043 Practice for Guarded-Hot-Plate De

29、sign Using Circu-lar Line-Heat SourcesC1044 Practice for Using a Guarded-Hot-Plate Apparatus orThin-Heater Apparatus in the Single-Sided ModeC1045 Practice for Calculating Thermal Transmission Prop-erties Under Steady-State ConditionsC1058 Practice for Selecting Temperatures for Evaluatingand Report

30、ing Thermal Properties of Thermal InsulationC1363 Test Method for Thermal Performance of BuildingMaterials and Envelope Assemblies by Means of a HotBox ApparatusE230 Specification for Temperature-Electromotive Force(emf) Tables for Standardized ThermocouplesE691 Practice for Conducting an Interlabor

31、atory Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 8302 Thermal InsulationDetermination of Steady-State Areal Thermal Resistance and Related PropertiesGuarded-Hot-Plate Apparatus42.3 ASTM Adjuncts:ASTMTable of Theoretical Maximum Thickness of Specimens andAssociated Errors5De

32、scriptions of Three Guarded-Hot-Plate Designs5Line-Heat-Source Guarded Hot-Plate Apparatus63. Terminology3.1 For definitions of terms and symbols used in this testmethod, refer to Terminology C168 and the following subsec-tions.3.2 Definitions of Terms Specific to This Standard:3.2.1 auxiliary cold

33、surface assembly, nthe plate thatprovides an isothermal boundary at the outside surface of theauxiliary insulation.3.2.2 auxiliary insulation, ninsulation placed on the backside of the hot-surface assembly, in place of a second testspecimen, when the single sided mode of operation is used.(Synonymba

34、ckflow specimen.)3.2.3 cold surface assembly, nthe plates that provide anisothermal boundary at the cold surfaces of the test specimen.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume inf

35、ormation, refer to the standards Document Summary page onthe ASTM website.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.5Available from ASTM Headquarters, Order Adjunct: ADJC0177.6Available from ASTM Headquarters, Order

36、 Adjunct: ADJC1043.C177 1923.2.4 controlled environment, nthe environment in whichan apparatus operates.3.2.5 guard, npromotes one-dimensional heat flow. Pri-mary guards are planar, additional coplanar guards can be usedand secondary or edge guards are axial.3.2.6 guarded-hot-plate apparatus, nan as

37、sembly, con-sisting of a hot surface assembly and two isothermal coldsurface assemblies.3.2.7 guarded-hot-plate, nthe inner (rectangular or circu-lar) plate of the hot surface assembly, that provides the heatinput to the metered section of the specimen(s).3.2.8 hot surface/assembly, nthe complete ce

38、nter assem-bly providing heat to the specimen(s) and guarding for themeter section.3.2.9 metered section, nthe portion of the test specimen(or auxiliary insulation) through which the heat input to theguarded-hot-plate flows under ideal guarding conditions.3.2.10 mode, double-sided, noperation of the

39、 guarded-hot-plate apparatus for testing two specimens, each specimenplaced on either side of the hot surface assembly.3.2.11 mode, single-sided, noperation of the guarded-hot-plate apparatus for testing one specimen, placed on one side ofthe hot-surface assembly.3.2.12 thermal transmission properti

40、es, nthose propertiesof a material or system that define the ability of a material orsystem to transfer heat such as thermal resistance, thermalconductance, thermal conductivity and thermal resistivity, asdefined by Terminology C168.3.3 SymbolsThe symbols used in this test method havethe following s

41、ignificance:3.3.1 mspecimen metered section density, kg/m3.3.3.2 sspecimen density, kg/m3.3.3.3 specimen thermal conductivity, W/(m K).3.3.4 guardthermal conductivity of the material in theprimary guard region, W/(m K).3.3.5 Stefan-Boltzmann constant, W/m2K4.3.3.6 Ametered section area normal to hea

42、t flow, m2.3.3.7 Agarea of the gap between the metered section andthe primary guard, m2.3.3.8 Amarea of the physical metered section (identified asguarded hot plate in Fig. 1 and Fig. 2), m2.3.3.9 Asarea of the entire specimen, m2.3.3.10 Cthermal conductance, W/(m2K).3.3.11 Cithe specific heat of th

43、e ith component of themetered section, J/(kg K).3.3.12 dT/dtpotential or actual drift rate of the meteredsection, K/s.3.3.13 Lin-situ specimen thickness, m.3.3.14 mmass of the specimen in the metered section, kg.3.3.15 mithe mass of the ith component, kg.3.3.16 msmass of the specimen, kg.3.3.17 Qhea

44、t flow rate in the metered section, W.3.3.18 qheat flux (heat flow rate per unit area), Q, througharea, A, W/m2.3.3.19 Qgelateral edge heat flow rate between primaryGuard and Controlled Environment, W.3.3.20 Qgplateral heat flow rate across the gap, W.3.3.21 Qgrdguard heat flow through Specimen, W.3

45、.3.22 Qseedge heat flow between Specimen and Con-trolled Environment, W.3.3.23 Rthermal resistance, m2K/W.3.3.24 Ttemperature difference across the specimen,ThTc.FIG. 1 General Arrangement of the Mechanical Components ofthe Guarded-Hot-Plate ApparatusFIG. 2 Illustration of Idealized Heat Flow in a G

46、uarded-Hot-PlateApparatusC177 1933.3.25 Tccold surface temperature, K.3.3.26 Thhot surface temperature, K.3.3.27 Tmmean temperature, K, (Th+Tc)/2.3.3.27.1 Discussion The Guarded-Hot-Plate Apparatusprovides a means for measurement of steady state heat fluxthrough insulation materials, that consists o

47、f a guarded heaterunit, comprised of a center metering area and concentricseparately heated guards, and an opposite, similarly sizedcooling plate. Specimens are placed in the space between theheater plate and the cooling plate for testing. The guarded-hot-plate is operated as a single or double side

48、d apparatus.Insulation thermal properties are calculated from measure-ments of metering area, energy input, temperatures, andthickness. The guarded-hot-plate, which provides an absolutemeasurement of heat flux, has been shown to be applicable formost insulating materials over a wide range of tempera

49、tureconditions.4. Summary of Test Method4.1 Fig. 1 illustrates the main components of the idealizedsystem: two isothermal cold surface assemblies and a guarded-hot-plate. It is possible that some apparatuses will have morethan one guard. The guarded-hot-plate is composed of ametered section thermally isolated from a concentric primaryguard by a definite separation or gap. Some apparatus mayhave more than one guard. The test specimen is sandwichedbetween these three units as shown in Fig. 1. In the double-sided mode of measurement