1、Designation:C 351 92b(Reapproved 1999)e1Standard Test Method forMean Specific Heat of Thermal Insulation1This standard is issued under the fixed designation C 351;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revis
2、ion.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.e1NOTESection 6.1.3.1 was editorially updated in June 2007.1.Scope1.1 This test method covers the determination of meanspecific heat of thermal
3、 insulating materials.The materialsmust be essentially homogeneous and composed of matter inthe solid state.1.2 This test method employs the classical method ofmixtures.This provides procedures and apparatus simpler thanthose generally used in scientific calorimetry,an accuracy thatis adequate for m
4、ost thermal insulating purposes,and a degreeof precision that is reproducible by laboratory technicians ofaverage skill.While this test method was developed for testingthermal insulations,it is easily adaptable to measuring thespecific heat of other materials.1.3 The test procedure provides for a me
5、an temperature ofapproximately 60C(100 to 20C temperature range),usingwater as the calorimetric fluid.By substituting other calorimet-ric fluids the temperature range may be changed as desired.1.4 The values stated in SI units are to be regarded as thestandard.1.5 This standard does not purport to a
6、ddress 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.2.Referenced Documents2.1 ASTM Standards:2E 1 Specificati
7、on for ASTM Liquid-in-Glass Thermometers3.Terminology3.1 Definitions:3.1.1 mean specific heatthe quantity of heat required tochange the temperature of a unit mass of a substance onedegree,measured as the average quantity over the temperaturerange specified.(It is distinguished from true specific hea
8、t bybeing an average rather than a point value.)The unit ofmeasurement is J/kgK.3.1.2 thermal capacitythe amount of heat necessary tochange the temperature of the body one degree.For a homo-geneous body it is the product of mass and specific heat.For anonhomogeneous body it is the sum of the product
9、s of massand specific heat of the individual constituents.Thermalcapacity has the units of J/K.3.1.3 thermal diffusivitythe ratio of thermal conductivityof a substance to the product of its density and specific heat.Common unit for this property is m2/s.3.1.4 water equivalentthe mass of water that r
10、equires thesame amount of heat as the given body in order to change itstemperature by an equal amount.4.Summary of Test Method4.1 The method of mixtures used in this test method consistsessentially of adding a known mass of material at a known hightemperature to a known mass of water at a known lowt
11、emperature and determining the equilibrium temperature thatresults.The heat absorbed by the water and the containingvessel can be calculated and this value equated to the expres-sion for the heat given up by the hot material.From thisequation3the unknown specific heat can be calculated.5.Significanc
12、e and Use5.1 Mean specific heat is an essential property of a thermalinsulating material when the latter is used under conditions ofunsteady or transient heat flow.It is a part of the parameter,thermal diffusivity,which governs the rate of temperaturediffusion through insulation.It is a basic thermo
13、dynamicproperty of all substances,the value of which depends uponchemical composition and temperature.NOTE1Specific heat of insulations,as measured by this test method,using small specimens of a multi-component composite or of a low-density product that has to be highly compressed,may not be directl
14、yapplicable for use in calculations involving transient thermal response.1This test method is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Aug.15,1992.Published October 1992.Ori
15、ginallyapproved in 1954.Last previous edition approved in 1999 as C 351 92b(1999).2For referenced ASTM standards,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 ont
16、he ASTM website.3Weber,R.L.,Heat and Temperature Measurement,Prentice-Hall,New York,NY,1950.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.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 The applicability of the results will depend upon a system being analyzed,the desired accuracy,and the relative amounts,and specific heats o