ASTM C1045-2007(2013) Standard Practice for Calculating Thermal Transmission Properties Under Steady-State Conditions《稳态条件下热传递性能计算的标准实施规程》.pdf

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1、Designation: C1045 07 (Reapproved 2013)Standard Practice forCalculating Thermal Transmission Properties Under Steady-State Conditions1This standard is issued under the fixed designation C1045; the number immediately following the designation indicates the year oforiginal adoption or, in the case of

2、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.1. Scope1.1 This practice provides the user with a uniform procedurefor calculating the thermal transmission

3、 properties of a materialor system from data generated by steady state, one dimensionaltest methods used to determine heat flux and surface tempera-tures. This practice is intended to eliminate the need for similarcalculation sections in Test Methods C177, C335, C518,C1033, C1114 and C1363 and Pract

4、ices C1043 and C1044 bypermitting use of these standard calculation forms by refer-ence.1.2 The thermal transmission properties described include:thermal conductance, thermal resistance, apparent thermalconductivity, apparent thermal resistivity, surface conductance,surface resistance, and overall t

5、hermal resistance or transmit-tance.1.3 This practice provides the method for developing theapparent thermal conductivity as a function of temperaturerelationship for a specimen from data generated by standardtest methods at small or large temperature differences. Thisrelationship can be used to cha

6、racterize material for compari-son to material specifications and for use in calculationprograms such as Practice C680.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This practice includes a discussion of the definition

7、s andunderlying assumptions for the calculation of thermal trans-mission properties. Tests to detect deviations from theseassumptions are described. This practice also considers thecomplicating effects of uncertainties due to the measurementprocesses and material variability. See Section 7.1.6 This

8、practice is not intended to cover all possible aspectsof thermal properties data base development. For newmaterials, the user should investigate the variations in thermalproperties seen in similar materials. The information containedin Section 7, theAppendix and the technical papers listed in theRef

9、erences section of this practice may be helpful in determin-ing whether the material under study has thermal propertiesthat can be described by equations using this practice. Someexamples where this method has limited application include:(1) the onset of convection in insulation as described inRefer

10、ence (1);(2) a phase change of one of the insulationsystem components such as a blowing gas in foam; and (3) theinfluence of heat flow direction and temperature differencechanges for reflective insulations.2. Referenced Documents2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationC177

11、 Test Method for Steady-State Heat Flux Measure-ments and Thermal Transmission Properties by Means ofthe Guarded-Hot-Plate ApparatusC335 Test Method for Steady-State Heat Transfer Propertiesof Pipe InsulationC518 Test Method for Steady-State Thermal TransmissionProperties by Means of the Heat Flow M

12、eter ApparatusC680 Practice for Estimate of the Heat Gain or Loss and theSurface Temperatures of Insulated Flat, Cylindrical, andSpherical Systems by Use of Computer ProgramsC1033 Test Method for Steady-State Heat Transfer Proper-ties of Pipe Insulation Installed Vertically (Withdrawn2003)3C1043 Pra

13、ctice for Guarded-Hot-Plate Design Using Circu-lar Line-Heat SourcesC1044 Practice for Using a Guarded-Hot-Plate Apparatus orThin-Heater Apparatus in the Single-Sided ModeC1058 Practice for Selecting Temperatures for Evaluatingand Reporting Thermal Properties of Thermal InsulationC1114 Test Method f

14、or Steady-State Thermal TransmissionProperties by Means of the Thin-Heater Apparatus1This practice is under the jurisdiction of ASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Sept. 1, 2013. Published Janu

15、ary 2014. Originallyapproved in 1985. Last previous edition approved in 2007 as C1045 07. DOI:10.1520/C1045-07R13.2For 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 th

16、e standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1C1199 Test Method for Measuring the Steady-State

17、ThermalTransmittance of Fenestration Systems Using Hot BoxMethodsC1363 Test Method for Thermal Performance of BuildingMaterials and Envelope Assemblies by Means of a HotBox ApparatusE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aL

18、ot or Process3. Terminology3.1 Definitions The definitions and terminology of thispractice are intended to be consistent with Terminology C168.However, because exact definitions are critical to the use of thispractice, the following equations are defined here for use in thecalculations section of th

19、is practice.3.2 SymbolsThe symbols, terms and units used in thispractice are the following:A = specimen area normal to heat flux direction, m2,C = thermal conductance, W/(m2 K),hc= surface heat transfer coefficient, cold side,W/(m2 K),hh= surface heat transfer coefficient, hot side,W/(m2 K),L = thic

20、kness of a slab in heat transfer direction, m,Lp= metering area length in the axial direction, m,q = one-dimensional heat flux (time rate of heat flowthrough metering area divided by the apparatusmetering area A), W/m2,Q = time rate of one-dimensional heat flow through themetering area of the test a

21、pparatus, W,r = thermal resistivity, K m/K,ra= apparent thermal resistivity, K m/K,rin= inside radius of a hollow cylinder, m,rout= outside radius of a hollow cylinder, m,R = thermal resistance, m2 K/W,Rc= surface thermal resistance, cold side, m2 K/W,Rh= surface thermal resistance, hot side, m2 K/W

22、,Ru= overall thermal resistance, m2 K/W,T = temperature, K,T1= area-weighted air temperature 75 mm or more fromthe hot side surface, K,T2= area-weighted air temperature 75 mm or more fromthe cold side surface, K,Tc= area-weighted temperature of the specimen coldsurface, K,Th= area-weighted temperatu

23、re of specimen hot surface,K,Tin= temperature at the inner radius, K,Tm= specimen mean temperature, average of two oppo-site surface temperatures, (Th+ Tc)/2, K,Tout= temperature at the outer radius, K,T = temperature difference, K,Ta-a= temperature difference, air to air, (T1 T2), K,Ts-s= temperatu

24、re difference, surface to surface,(Th Tc), K,U = thermal transmittance, W/(m2 K), andx = linear dimension in the heat flow direction, m, = thermal conductivity, W/(m K),a= apparent thermal conductivity, W/(m K),(T) = functional relationship between thermal conductiv-ity and temperature, W/(m K),exp=

25、 experimental thermal conductivity, W/(m K),m= mean thermal conductivity, averaged with respect totemperature from Tcto Th, W/(m K), (see sections6.4.1 and Appendix X3).NOTE 1Subscripts h and c are used to differentiate between hot sideand cold side surfaces.3.3 Thermal Transmission Property Equatio

26、ns:3.3.1 Thermal Resistance, R, is defined in TerminologyC168. It is not necessarily a unique function of temperature ormaterial, but is rather a property determined by the specificthickness of the specimen and by the specific set of hot-sideand cold-side temperatures used to measure the thermal res

27、is-tance.R 5A Th2 Tc!Q(1)3.3.2 Thermal Conductance, C:C 5QATh2 Tc!51R(2)NOTE 2Thermal resistance, R, and the corresponding thermalconductance, C, are reciprocals; that is, their product is unity. These termsapply to specific bodies or constructions as used, either homogeneous orheterogeneous, betwee

28、n two specified isothermal surfaces.3.3.3 Eq 1, Eq 2, Eq 3, Eq 5and Eq 7-13 are for rectangularcoordinate systems only. Similar equations for resistance, etc.can be developed for a cylindrical coordinate system providingthe difference in areas is considered. (See Eq 4 and Eq 6.) Inpractice, for cyli

29、ndrical systems such as piping runs, thethermal resistance shall be based upon the pipe external surfacearea since that area does not change with different insulationthickness3.3.4 ApparentThermal conductivity, a, is defined in Ter-minology C168.Rectangular coordinates:a5QLA Th2 Tc!(3)Cylindrical co

30、ordinates:a5Qlnrout/rin!2 Lp Tin2 Tout!(4)3.3.5 Apparent Thermal Resistivity, ra, is defined in Termi-nology C168.Rectangular Coordinates:ra5A Th2 Tc!QL51a(5)Cylindrical Coordinates:ra52 Lp Tin2 Tout!Qlnrout/rin!51a(6)NOTE 3The apparent thermal resistivity, ra, and the correspondingthermal conductiv

31、ity, a, are reciprocals, that is, their product is unity.These terms apply to specific materials tested between two specifiedisothermal surfaces. For this practice, materials are considered homoge-neous when the value of the thermal conductivity or thermal resistivity isnot significantly affected by

32、 variations in the thickness or area of thesample within the normally used range of those variables.C1045 07 (2013)23.4 Transmission Property Equations for ConvectiveBoundary Conditions:3.4.1 Surface Thermal Resistance, Ri, the quantity deter-mined by the temperature difference at steady-state betwe

33、en anisothermal surface and its surrounding air that induces a unitheat flow rate per unit area to or from the surface. Typically,this parameter includes the combined effects of conduction,convection, and radiation. Surface resistances are calculated asfollows:Rh5A T12 Th!Q(7)Rc5A Tc2 T2!Q(8)3.4.2 S

34、urface Heat Transfer Coeffcient, hi, is often calledthe film coefficient. These coefficients are calculated as fol-lows:hh5QA T12 Th!51Rh(9)hc5QA Tc2 T2!51Rc(10)NOTE 4The surface heat transfer coefficient, hi, and the correspondingsurface thermal resistance, Ri, are reciprocals, that is, their produ

35、ct isunity.These properties are measured at a specific set of ambient conditionsand are therefore only correct for the specified conditions of the test.3.4.3 Overall Thermal Resistance, RuThe quantity deter-mined by the temperature difference, at steady-state, betweenthe air temperatures on the two

36、sides of a body or assembly thatinduces a unit time rate of heat flow per unit area through thebody. It is the sum of the resistance of the body or assemblyand of the two surface resistances and may be calculated asfollows:Ru5A T12 T2!Q(11)5 Rc1R1Rh3.4.4 Thermal Transmittance, U (sometimes called ov

37、erallcoefficient of thermal transfer), is calculated as follows:U 5QA T12 T2!51Ru(12)The transmittance can be calculated from the thermal con-ductance and the surface coefficients as follows:1/U 5 1/hh!11/C!11/hc! (13)NOTE 5Thermal transmittance, U, and the corresponding overallthermal resistance, R

38、u, are reciprocals; that is, their product is unity. Theseproperties are measured at a specific set of ambient conditions and aretherefore only correct for the specified conditions of the test.4. Significance and Use4.1 ASTM thermal test method descriptions are complexbecause of added apparatus deta

39、ils necessary to ensure accurateresults.As a result, many users find it difficult to locate the datareduction details necessary to reduce the data obtained fromthese tests. This practice is designed to be referenced in thethermal test methods, thus allowing those test methods toconcentrate on experi

40、mental details rather than data reduction.4.2 This practice is intended to provide the user with auniform procedure for calculating the thermal transmissionproperties of a material or system from standard test methodsused to determine heat flux and surface temperatures. Thispractice is intended to e

41、liminate the need for similar calculationsections in the ASTM Test Methods (C177, C335, C518,C1033, C1114, C1199, and C1363) by permitting use of thesestandard calculation forms by reference.4.3 This practice provides the method for developing thethermal conductivity as a function of temperature for

42、 aspecimen from data taken at small or large temperaturedifferences. This relationship can be used to characterizematerial for comparison to material specifications and for usein calculations programs such as Practice C680.4.4 Two general solutions to the problem of establishingthermal transmission

43、properties for application to end-useconditions are outlined in Practice C1058. (Practice C1058should be reviewed prior to use of this practice.) One is tomeasure each product at each end-use condition. This solutionis rather straightforward, but burdensome, and needs no otherelaboration. The second

44、 is to measure each product over theentire temperature range of application conditions and to usethese data to establish the thermal transmission propertydependencies at the various end-use conditions. One advantageof the second approach is that once these dependencies havebeen established, they ser

45、ve as the basis for estimating theperformance for a given product at other conditions.Warning The use of a thermal conductivity curve developedin Section 6 must be limited to a temperature range that doesnot extend beyond the range of highest and lowest test surfacetemperatures in the test data set

46、used to generate the curve.5. Determination of Thermal Transmission Properties fora Specific Set of Temperature Conditions5.1 Choose the thermal test parameter ( or r, R or C, U orRu) to be calculated from the test results. List any additionalinformation required by that calculation i.e. heat flux,t

47、emperatures, dimensions. Recall that the selected test param-eter might limit the selection of the thermal test method used in5.2.5.2 Select the appropriate test method that provides thethermal test data required to determine the thermal transmis-sion property of interest for the sample material bei

48、ng studied.(See referenced papers and Appendix X1 for help with thisdetermination.5.3 Using that test method, determine the required steady-state heat flux and temperature data at the selected testcondition.NOTE 6The calculation of specific thermal transmission propertiesrequires that: (1) the therm

49、al insulation specimen is homogeneous, asdefined in Terminology C168 or, as a minimum, appears uniform acrossthe test area; (2) the measurements are taken only after steady-state hasbeen established; ( 3) the heat flows in a direction normal to the isothermalsurfaces of the specimen; (4) the rate of flow of heat is known; (5) thespecimen dimensions, that is, heat flow path length parallel to heat flow,and area perpendicular to heat flow, are known; and (6) both specimensurface temperatures (and equivalently, the