1、Designation: C 1045 07Standard Practice forCalculating Thermal Transmission Properties Under Steady-State Conditions1This standard is issued under the fixed designation C 1045; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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.1. Scope1.1 This practice provides the user with a uniform procedurefor calculating the thermal transmission properties of
3、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 C 177, C 335, C 518,C 1033, C 1114 and C 1363 and Practices C 10
4、43 and C 1044by permitting use of these standard calculation forms byreference.1.2 The thermal transmission properties described include:thermal conductance, thermal resistance, apparent thermalconductivity, apparent thermal resistivity, surface conductance,surface resistance, and overall thermal re
5、sistance 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 characterize
6、 material for compari-son to material specifications and for use in calculationprograms such as Practice C 680.1.4 The SI unit values used in this practice are consideredstandard.1.5 This practice includes a discussion of the definitions andunderlying assumptions for the calculation of thermal trans
7、-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 practice is not intended to cover all possible aspectsof thermal
8、 properties data base development. For new materi-als, the user should investigate the variations in thermalproperties seen in similar materials. The information containedin Section 7, theAppendix and the technical papers listed in theReferences section of this practice may be helpful in determin-in
9、g 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 inReference (1);(2) a phase change of one of the insulationsystem com
10、ponents 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:2C 168 Terminology Relating to Thermal InsulationC 177 Test Method for Steady-State Heat Flux Measure-ments and Th
11、ermal Transmission Properties by Means ofthe Guarded-Hot-Plate ApparatusC 335 Test Method for Steady-State Heat Transfer Proper-ties of Pipe InsulationC 518 Test Method for Steady-State Thermal TransmissionProperties by Means of the Heat Flow Meter ApparatusC 680 Practice for Estimate of the Heat Ga
12、in or Loss andthe Surface Temperatures of Insulated Flat, Cylindrical,and Spherical Systems by Use of Computer ProgramsC 1033 Test Method for Steady-State Heat Transfer Prop-erties of Pipe Insulation Installed Vertically3C 1043 Practice for Guarded-Hot-Plate Design Using Cir-cular Line-Heat SourcesC
13、 1044 Practice for Using a Guarded-Hot-Plate Apparatusor Thin-Heater Apparatus in the Single-Sided ModeC 1058 Practice for Selecting Temperatures for Evaluatingand Reporting Thermal Properties of Thermal InsulationC 1114 Test Method for Steady-State Thermal TransmissionProperties by Means of the Thi
14、n-Heater ApparatusC 1199 Test Method for Measuring the Steady-State Ther-mal Transmittance of Fenestration Systems Using Hot BoxMethodsC 1363 Test Method for Thermal Performance of BuildingMaterials and Envelope Assemblies by Means of a HotBox Apparatus1This practice is under the jurisdiction of AST
15、M Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Nov. 1, 2007. Published November 2007. Originallyapproved in 1985. Last previous edition approved in 2001 as C 1045 01.2For referenced ASTM standards, visit the
16、 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.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19
17、428-2959, United States.E 122 Practice for Calculating Sample Size to Estimate,With Specified Precision, the Average for a Characteristicof a Lot or Process3. Terminology3.1 Definitions The definitions and terminology of thispractice are intended to be consistent with Terminology C 168.However, beca
18、use exact definitions are critical to the use of thispractice, the following equations are defined here for use in thecalculations section of this 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 c
19、onductance, W/(m2 K),hc= surface heat transfer coefficient, cold side,W/(m2 K),hh= surface heat transfer coefficient, hot side,W/(m2 K),L = thickness 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 flowthroug
20、h metering area divided by the apparatusmetering area A), W/m2,Q = time rate of one-dimensional heat flow throughthe metering area of the test apparatus, 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 holl
21、ow 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,Ru= overall thermal resistance, m2 K/W,T = temperature, K,T1= area-weighted air temperature 75 mm or morefrom the hot side surface, K,T2= area-weighted air
22、 temperature 75 mm or morefrom the cold side surface, K,Tc= area-weighted temperature of the specimen coldsurface, K,Th= area-weighted temperature of specimen hot sur-face, K,Tin= temperature at the inner radius, K,Tm= specimen mean temperature, average of two op-posite surface temperatures, (Th+ Tc
23、)/2, K,Tout= temperature at the outer radius, K,DT = temperature difference, K,DTa-a= temperature difference, air to air, ( T1 T2), K,DTs-s= temperature difference, surface to surface,(Th Tc), K,U = thermal transmittance, W/(m2 K), andx = linear dimension in the heat flow direction, m,l = thermal co
24、nductivity, W/(m K),la= apparent thermal conductivity, W/(m K),l(T) = functional relationship between thermal conduc-tivity and temperature, W/(m K),lexp= experimental thermal conductivity, W/(m K),lm= mean thermal conductivity, averaged with respectto temperature from Tcto Th, W/(m K), (seesections
25、 6.4.1 and Appendix X3).NOTE 1Subscripts h and c are used to differentiate between hot sideand cold side surfaces.3.3 Thermal Transmission Property Equations:3.3.1 Thermal Resistance, R, is defined in TerminologyC 168. It is not necessarily a unique function of temperature ormaterial, but is rather
26、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 resis-tance.R 5A Th Tc!Q(1)3.3.2 Thermal Conductance, C:C 5QA Th2 Tc!51R(2)NOTE 2Thermal resistance, R, and the corresponding thermal con-ductance,
27、 C, are reciprocals; that is, their product is unity. These termsapply to specific bodies or constructions as used, either homogeneous orheterogeneous, between 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
28、resistance, etc.can be developed for a cylindrical coordinate system providingthe difference in areas is considered. (See Eq 4 and Eq 6.) Inpractice, for cylindrical systems such as piping runs, thethermal resistance shall be based upon the pipe external surfacearea since that area does not change w
29、ith different insulationthickness3.3.4 ApparentThermal conductivity, la, is defined in Ter-minology C 168.Rectangular coordinates:la5QLA Th2 Tc!(3)Cylindrical coordinates:la5Q lnrout/rin!2 p LpTin2 Tout!(4)3.3.5 Apparent Thermal Resistivity,ra, is defined in Termi-nology C 168.Rectangular Coordinate
30、s:ra5A Th2 Tc!QL51la(5)Cylindrical Coordinates:ra52 p LpTin2 Tout!Q ln rout/ rin!51la(6)NOTE 3The apparent thermal resistivity, ra, and the correspondingthermal conductivity, la, are reciprocals, that is, their product is unity.These terms apply to specific materials tested between two specifiedisot
31、hermal surfaces. For this practice, materials are considered homoge-neous when the value of the thermal conductivity or thermal resistivity isnot significantly affected by variations in the thickness or area of thesample within the normally used range of those variables.C10450723.4 Transmission Prop
32、erty Equations for ConvectiveBoundary Conditions:3.4.1 Surface Thermal Resistance, Ri, the quantity deter-mined by the temperature difference at steady-state between anisothermal surface and its surrounding air that induces a unitheat flow rate per unit area to or from the surface. Typically,this pa
33、rameter 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 Surface Heat Transfer Coeffcient, hi, is often calledthe film coefficient. These coefficients are calculated as fol-lows:hh5QA T12 Th!51Rh
34、(9)hc5QA Tc2 T2!51Rc(10)NOTE 4The surface heat transfer coefficient, hi, and the correspondingsurface thermal resistance, Ri, are reciprocals, that is, their product isunity.These properties are measured at a specific set of ambient conditionsand are therefore only correct for the specified conditio
35、ns 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 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 t
36、he body or assemblyand of the two surface resistances and may be calculated asfollows:Ru5A T12 T2!Q(11)5 Rc1 R 1 Rh3.4.4 Thermal Transmittance, U (sometimes called overallcoefficient of thermal transfer), is calculated as follows:U 5QA T1 T2!51Ru(12)The transmittance can be calculated from the therm
37、al con-ductance and the surface coefficients as follows:1/U 5 1/hh! 1 1/C! 1 1/hc! (13)NOTE 5Thermal transmittance, U, and the corresponding overallthermal resistance, Ru, are reciprocals; that is, their product is unity. Theseproperties are measured at a specific set of ambient conditions and areth
38、erefore only correct for the specified conditions of the test.4. Significance and Use4.1 ASTM thermal test method descriptions are complexbecause of added apparatus details necessary to ensure accurateresults.As a result, many users find it difficult to locate the datareduction details necessary to
39、reduce the data obtained fromthese tests. This practice is designed to be referenced in thethermal test methods, thus allowing those test methods toconcentrate on experimental details rather than data reduction.4.2 This practice is intended to provide the user with auniform procedure for calculating
40、 the thermal transmissionproperties of a material or system from standard test methodsused to determine heat flux and surface temperatures. Thispractice is intended to eliminate the need for similar calculationsections in the ASTM Test Methods (C 177, C 335, C 518,C 1033, C 1114, C 1199, and C 1363)
41、 by permitting use ofthese standard calculation forms by reference.4.3 This practice provides the method for developing thethermal conductivity as a function of temperature for aspecimen from data taken at small or large temperaturedifferences. This relationship can be used to characterizematerial f
42、or comparison to material specifications and for usein calculations programs such as Practice C 680.4.4 Two general solutions to the problem of establishingthermal transmission properties for application to end-useconditions are outlined in Practice C 1058. (Practice C 1058should be reviewed prior t
43、o 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 is to measure each product over theentire temperature range of application conditions and to usethese data to establish
44、the thermal transmission propertydependencies at the various end-use conditions. One advantageof the second approach is that once these dependencies havebeen established, they serve as the basis for estimating theperformance for a given product at other conditions.WarningThe use of a thermal conduct
45、ivity 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 used to generate the curve.5. Determination of Thermal Transmission Properties fora Specific Set of Temperature Conditions
46、5.1 Choose the thermal test parameter (l 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, tempera-tures, dimensions. Recall that the selected test parameter mightlimit the selection of the thermal test method us
47、ed in 5.2.5.2 Select the appropriate test method that provides thethermal test data required to determine the thermal transmis-sion property of interest for the sample material being studied.(See referenced papers and Appendix X1 for help with thisdetermination.5.3 Using that test method, determine
48、the required steady-state heat flux and temperature data at the selected testcondition.NOTE 6The calculation of specific thermal transmission propertiesrequires that: (1) the thermal insulation specimen is homogeneous, asdefined in Terminology C 168 or, as a minimum, appears uniform acrossthe test a
49、rea; (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 temperature difference acrossthe specimen) are known; and in the case of a hot box systems test, bothair curtain temperatures must be kno
