1、Designation: C 177 04Standard Test Method forSteady-State Heat Flux Measurements and ThermalTransmission Properties by Means of the Guarded-Hot-PlateApparatus1This standard is issued under the fixed designation C 177; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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
3、. 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 ap
4、paratus 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
5、-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-dures
6、 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. Theus
7、er should consult the standard practices on the single-sidedmode of operation, Practice C 1044, and on the line sourceapparatus, Practice C 1043, 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 TestMethods C 976 or C 236 for guidance in testing these systems.1.9 Calculations of thermal transmission properties basedupon measurements using this method shall be performed inconformance with Pr
12、actice C 1045.1.10 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 a
13、nd systems.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 t
14、o theiraccuracy. 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
15、 offer difficulties 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 dire
16、ct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 1942. Last previous edition approved in 1997 as C 177 97 .2The boldface numbers given in parentheses refer to the list of references at theend of this
17、standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.modifying the apparatus, to become a designer or builder, orboth, on whom the demands for fundamental understandingand careful experimental technique are even greater. Standard
18、-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 moun
19、ting 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 prin
20、ciples 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 the
21、report. A discussion of thesignificant error factors involved is included.1.14 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly. Either SI or Imperial units may be used in the report,unless otherwise specified.1.15 This standard
22、 does not purport to address all of thesafety concerns, if any, associated with 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 stateme
23、nts are given in Note 21.1.16 Major sections within this test method are arranged asfollows:Section SectionScope 1Referenced Documents 2Terminology 3Summary of Test Method 4Significance and Use 5Apparatus 6Specimen Preparation and Conditioning 7Procedure 8Calculation of Results 9Report 10Precision a
24、nd 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 of Thickness A1.1Measuring Thickness A1.2Limitations Due to Apparatus A1.
25、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 or Thermal Resistivity Error Analysis A1.9Uncertainty Verification A1.10
26、2. Referenced Documents2.1 ASTM Standards:3C 168 Terminology Relating to Thermal InsulationC 236 Test Method for Steady-State Thermal Performanceof Building Assemblies by Means of a Guarded Hot Box4C 518 Test Method for Steady-State Thermal TransmissionProperties by Means of the Heat Flow Meter Appa
27、ratusC 687 Practice for Determination of Thermal Resistance ofLoose-Fill Building Insulation4C 976 Test Method for Thermal Performance of BuildingAssemblies by Means of a Calibrated Hot BoxC 1043 Practice for Guarded-Hot-Plate Design Using Cir-cular Line-Heat SourcesC 1044 Practice for Using a Guard
28、ed-Hot-Plate Apparatusor Thin-Heater Apparatus in the Single-Sided ModeC 1045 Practice for Calculating Thermal TransmissionProperties Under Steady-State ConditionsC 1058 Practice for Selecting Temperatures for Evaluatingand Reporting Thermal Properties of Thermal InsulationE 230 Specification for Te
29、mperature-Electromotive Force(EMF) Tables for Standardized ThermocouplesE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 8302 Thermal InsulationDetermination of Steady-State Areal Thermal Resistance and Related PropertiesGuarded-Ho
30、t-Plate Apparatus52.3 ASTM Adjuncts:ASTMTable of Theoretical Maximum Thickness of Specimens andAssociated Errors6Descriptions of Three Guarded-Hot-Plate Designs6Line-Heat-Source Guarded Hot-Plate Apparatus73. Terminology3.1 Definitions:3.1.1 For definitions of terms and symbols used in this testmeth
31、od, refer to Terminology C 168 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 an isothermal boundary at the outside surface of theauxiliary insulation.3.2.2 auxiliary insulation, ninsulation placed on
32、the backside of the hot-surface assembly, in place of a second testspecimen, when the single sided mode of operation is used. (Synonymbackflow specimen.)3.2.3 cold surface assembly, nthe plates that provide anisothermal boundary at the cold surfaces of the test specimen.3For referenced ASTM standard
33、s, 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.4Withdrawn.5Available from American National Standards Institute, 11 W. 42nd St., 13thFloo
34、r, New York, NY 10036.6Available from ASTM Headquarters, Order Adjunct: ADJCO177.7Available from ASTM Headquarters, Order Adjunct: ADJC1043.C1770423.2.4 controlled environment, nthe environment in whichan apparatus operates.3.2.5 guard, npromotes one-dimensional heat flow. Pri-mary guards are planar
35、, 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 assembly and two isothermal coldsurface assemblies.3.2.7 guarded-hot-plate, nthe inner (rectangular or circu-lar) plate of the hot surface asse
36、mbly, 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 specimen(s) and guarding for themeter section.3.2.9 metered section, nthe portion of the test specimen(or auxiliary insulation) through which t
37、he 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 two specimens, each specimenplaced on either side of the hot surface assembly.3.2.11 mode, single-sided, noperation of the guarded-hot-plat
38、e 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 system that define the ability of a material orsystem to transfer heat such as thermal resistance, thermalconductance, thermal conductivity a
39、nd thermal resistivity, asdefined by Terminology C 168.3.3 Symbols:SymbolsThe symbols used in this testmethod have the following significance:3.3.1 rm specimen metered 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
40、.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 metered 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
41、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 guard 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 t
42、he 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, 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
43、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 resistance, 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,
44、 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 of a guarded heaterunit, comprised of a center metering area and concentricseparately heated guards, and
45、 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 sided apparatus.Insulation thermal properties are calculated from measure-ments of metering area, energy in
46、put, 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 temperatureconditions.4. Summary of Test Method4.1 Fig. 1 illustrates the main components of the idealizedsyst
47、em: two isothermal cold surface assemblies and a guarded-hot-plate. The guarded-hot-plate is composed of a meteredsection thermally isolated from a concentric primary guard bya definite separation or gap. Some apparatus may have morethan one guard.The test specimen is sandwiched between thesethree u
48、nits as shown in Fig. 1. In the double-sided mode ofmeasurement, the specimen is actually composed of twopieces. The measurement in this case produces a result that isFIG. 1 General Arrangement of the Mechanical Components ofthe Guarded-Hot-Plate ApparatusC177043the average of the two pieces and the
49、refore 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 C 1044. For guidance in the use of a guarded-hot-plateincorporating the use of a line source heater, refer to PracticeC 1043.4.1.1 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 wh
