1、Designation:D789614Standard Test Method forThermal Conductivity,Thermal Diffusivity and VolumetricHeat Capacity of Engine Coolants and Related Fluids byTransient Hot Wire Liquid Thermal Conductivity Method1This standard is issued under the fixed designation D7896;the number immediately following the
2、 designation indicates the year oforiginal adoption 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.1.Scope1.1 This test method covers the use
3、of a transient hot wireliquid thermal conductivity method and associated equipment(the System)for the determination of thermal conductivity,thermal diffusivity and volumetric heat capacity of aqueousengine coolants,non-aqueous engine coolants,and relatedfluids.The System is intended for use in a lab
4、oratory.1.2 The System directly measures thermal conductivity andthermal diffusivity without the requirement to input anyadditional properties.Volumetric heat capacity is calculated bydividing the thermal conductivity by the thermal diffusivity ofthe sample measured.1.3 This test method can be appli
5、ed to any aqueous ornon-aqueous engine coolants or related fluid with thermalconductivity in the range of 0.1 to 1.0 W/mK.1.4 This test method excludes fluids that react with plati-num.1.5 The range of temperatures applicable to this test methodis 20 to 100C.1.6 This test method requires a sample of
6、 approximately 40mL.1.7 The System may be used without external pressurizationfor any fluid having a vapor pressure of 33.8 kPa(4.9 psia)orless at the test temperature.1.8 For a fluid having a vapor pressure greater than 33.8 kPa(4.9 psia)at the test temperature,external pressurization isrequired(se
7、e Annex A2).1.9 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.9.1 ExceptionInch-pound units are provided in 1.7,1.8,4.1,7.8,and A2.1 for information.1.10 This standard does not purport to address all of thesafety concerns,if
8、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:2D1176 Practice for Sampling and Preparing Aqueous S
9、olu-tions of Engine Coolants orAntirusts for Testing PurposesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions of Thermal Related Units:3.1.1 density(),nthe mass per unit volume of a sub-stance under specific conditions of pr
10、essure and temperature.Unit:kg/m3.3.1.2 specific heat capacity(Cp),nthe amount of heatrequired to raise the temperature of a unit mass of material by1C.See Annex A1.Unit:J/(kgK).3.1.3 thermal conductivity(),nrate of heat flow understeady conditions through unit area,per unit temperaturegradient in t
11、he direction perpendicular to the area.Unit:W/mK.3.1.4 thermal diffusivity(),na measure of the ability of asubstance to transmit a difference in temperature.Unit:m2/s.3.1.5 volumetric heat capacity(VHC),nthe amount ofheat required to raise the temperature of a unit volume ofmaterial by 1C.Volumetric
12、 heat capacity is the thermalconductivity of a material divided by its thermal diffusivity.Unit:J/m3K.3.2 Definitions of Terms Specific to This Standard:3.2.1 transient hot wire method,na method for measure-ment of thermal properties wherein a thin wire is immersed in1This test method is under the j
13、urisdiction of ASTM Committee D15 on EngineCoolants and Related Fluids,and is the direct responsibility of SubcommitteeD15.22 on Non-Aqueous Coolants.Current edition approved Feb.1,2014.Published June 2014.DOI:10.1520/D7896-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcont
14、act ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 a liquid specimen that is con
15、tained in a sampling cell.Aninstant of current is sent through the wire,heating both the wireand specimen.Immediately afterward,the resistance of thewire is measured with respect to time,while the wire cools.Atemperature-time profile of the specimen is produced and fromthis profile,thermal propertie
16、s are determined.3.2.1.1 dry bath,na temperature control peripheral with acentral heating well that receives the sampling cell containingthe liquid specimen for providing temperatures above ambient.3.2.1.2 heat exchanger and circulator,na temperaturecontrol peripheral consisting of a refrigerated/heated circulatorfor heating and cooling that is connected to a heat exchanger.The heat exchanger has a central well that receives thesampling cell containing the liquid specimen,for providingtemperatur
