1、Designation: C177 10Standard 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 Department of Defense.1. S
3、cope1.1 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 appar
4、atus 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-hot-pl
5、ate 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-dures us
6、ed 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. Theuser
7、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 caution
8、edhowever, 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 specimen co
9、nduc-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 and
10、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, can yie
11、ld 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 C1045.1.
12、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.Detai
13、led 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 theiraccuracy.
14、 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 difficult
15、ies to aperson without technical knowledge concerning theory of heatflow, temperature measurements and general testing practices.The user may also find it necessary, when repairing ormodifying the apparatus, to become a designer or builder, or1This test method is under the jurisdiction ofASTM Commit
16、tee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved June 1, 2010. Published August 2010. Originallyapproved in 1942. Last previous edition approved in 2004 as C177 04 . DOI:10.1520/C0177-10.2The boldface numbers given in
17、 parentheses refer to the list of references at theend of this standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.both, on whom the demands for fundamental understandingand careful experimental technique are even greater. Stand
18、ard-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, preconditioning, specimen m
19、ounting 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 accepted heat transfer p
20、rinciples 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 reported variable in t
21、he report. A discussion of thesignificant error factors involved is included.1.14 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.15 This standard does not purport to address all of thesafety concerns, if any, associated with
22、its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Note 21.1.16 Major sections within this test method are arrange
23、d asfollows:Section SectionScope 1Referenced Documents 2Terminology 3Summary of Test Method 4Significance and Use 5Apparatus 6Specimen Preparation and Conditioning 7Procedure 8Calculation of Results 9Report 10Precision and Bias 11Keywords 12FiguresGeneral Arrangement of the Mechanical Components of
24、the Guarded-Hot-Plate ApparatusFig. 1Illustration of Heat Flow in the Guarded-Hot-Plate Apparatus Fig.2Example Report Form Fig. 3AnnexesImportance of Thickness A1.1Measuring Thickness A1.2Limitations Due to Apparatus A1.3Limitations Due to Temperature A1.4Limitations Due to Specimen A1.5Random and S
25、ystematic Error Components A1.6Error Components for Variables A1.7Thermal Conductance or Thermal Resistance Error Analysis A1.8Thermal Conductivity or Thermal Resistivity Error Analysis A1.9Uncertainty Verification A1.102. Referenced Documents2.1 ASTM Standards:3C168 Terminology Relating to Thermal
26、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 Design Using Circu-lar Line-Heat SourcesC1044 Practice for Us
27、ing a Guarded-Hot-PlateApparatus orThin-Heater Apparatus in the Single-Sided ModeC1045 Practice for CalculatingThermalTransmission Prop-erties Under Steady-State ConditionsC1058 Practice for Selecting Temperatures for Evaluatingand Reporting Thermal Properties of Thermal InsulationC1363 Test Method
28、for Thermal Performance of BuildingMaterials and Envelope Assemblies by Means of a HotBox ApparatusE230 Specification and Temperature-Electromotive Force(EMF) Tables for Standardized ThermocouplesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO
29、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 Errors5Descriptions of Three Guarded-Hot-Plate Designs5Line-Heat-Source
30、 Guarded Hot-Plate Apparatus63. Terminology3.1 Definitions:3.1.1 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 surface assembly, n the plate thatprovides a
31、n 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. (Synonymbackflow specimen.)3For referenced ASTM stan
32、dards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor
33、, New York, NY 10036, http:/www.ansi.org.5Available from ASTM Headquarters, Order Adjunct: ADJC0177.6Available from ASTM Headquarters, Order Adjunct: ADJC1043.C177 1023.2.3 cold surface assembly, nthe plates that provide anisothermal boundary at the cold surfaces of the test specimen.3.2.4 controlle
34、d 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 assembly, con-sisting of a hot surface assem
35、bly 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 center assem-bly providing heat to the speci
36、men(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 guarded-hot-plate apparatus for testing t
37、wo 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 properties, n those propertiesof a material or sys
38、tem 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 Symbols:SymbolsThe symbols used in this testmethod have the following significance:3.3.1 rm specimen met
39、ered section density, kg/m3.3.3.2 rsspecimen density, kg/m3.3.3.3 lthermal conductivity, W/(m K).3.3.4 sStefan-Boltzmann constant, W/m2K4.3.3.5 Ametered section area normal to heat flow, m2.3.3.6 Agarea of the gap between the metered section andthe primary guard, m2.3.3.7 Amarea of the actual metere
40、d section, m2.3.3.8 Asarea of the total specimen, m2.3.3.9 Cthermal conductance, W/(m2K).3.3.10 Cithe specific heat of the ith component of themetered section, J/(kg K).3.3.11 dT/dtpotential or actual drift rate of the meteredsection, K/s.3.3.12 lgthermal conductivity of the material in theprimary g
41、uard region, W/(m K).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 Qheat flow rate in the metered section, W.3.3.18 qheat flux (heat flow rate per unit area), Q, throug
42、harea, 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.3.3.22 Qseedge heat flow between Specimen and Con-trolled Environment, W.3.3.23 Rthermal resistanc
43、e, m2K/W.3.3.24 D Ttemperature difference across the specimen,ThTc.3.3.25 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 ins
44、ulation materials, that consists of 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 o
45、perated as a single or double sided 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 mate
46、rials over a wide range of temperatureconditions.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. The guarded-hot-plate is composed of a meteredsection thermally isolated from a concentric prim
47、ary guard bya definite separation or gap. Some apparatus may have morethan one guard.The test specimen is sandwiched between thesethree units as shown in Fig. 1. In the double-sided mode ofmeasurement, the specimen is actually composed of twoFIG. 1 General Arrangement of the Mechanical Components of
48、the Guarded-Hot-Plate ApparatusC177 103pieces. The measurement in this case produces a result that isthe average of the two pieces and therefore it is important thatthe two pieces be closely identical. For guidance in the use ofthe one-sided mode of measurement, the user is directed toPractice C1044
49、. For guidance in the use of a guarded-hot-plateincorporating the use of a line source heater, refer to PracticeC1043.4.1.1 The guarded-hot-plate provides the power (heat flowper unit time) for the measurement and defines the actual testvolume, that is, that portion of the specimen that is actuallybeing measured. The function of the primary guard, andadditional coplanar guard where applicable, of the guarded-hot-plate apparatus is to provide the proper thermal conditionswithin the test volume to reduce lateral heat flow within theappar
