1、Designation: C1784 13Standard Test Method forUsing a Heat Flow Meter Apparatus for Measuring ThermalStorage Properties of Phase Change Materials andProducts1This standard is issued under the fixed designation C1784; the number immediately following the designation indicates the year oforiginal adopt
2、ion 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 measurement of non-steady-state heat flow int
3、o or out of a flat slab specimen to determinethe stored energy (that is, enthalpy) change as a function oftemperature using a heat flow meter apparatus (HFMA).1.2 In particular, this test method is intended to measure thesensible and latent heat storage capacity for products incorpo-rating phase-cha
4、nge materials (PCM).1.2.1 The storage capacity of a PCM is well defined via fourparameters: specific heats of both solid and liquid phases,phase change temperature(s) and phase change enthalpy (1).21.3 To more accurately predict thermal performance, infor-mation about the PCM products performance un
5、der dynamicconditions is needed to supplement the properties (thermalconductivity) measured under steady-state conditions.NOTE 1This test method defines a dynamic test protocol for productsor composites containing PCMs. Due to the macroscopic structure of theseproducts or composites, small sample si
6、zes used in conventional Differ-ential Scanning Calorimeter (DSC) measurements, as specified in E793and E967, are not representative of the relationship between temperatureand enthalpy storage of full-scale PCM products.1.4 This test method is based upon the HFMA technologyused for Test Method C518
7、but includes modifications forspecific heat and enthalpy change measurements for PCMproducts as outlined in this test method.1.5 Heat flow measurements are required at both the top andbottom HFMA plates for this test method. Therefore, this testmethod applies only to HFMAs that are equipped with at
8、leastone heat flux transducer on each of the two plates and that havethe capability for computerized data acquisition and tempera-ture control systems. Further, the amount of energy flowingthrough the transducers must be measureable at all points intime. Therefore, the transducer output shall never
9、be saturatedduring a test.1.6 This test method makes a series of measurements todetermine the enthalpy storage of a test specimen over atemperature range. First, both HFMA plates are held at thesame constant temperature until steady state is achieved.Steady state is defined by the reduction in the a
10、mount of energyentering the specimen from both plates to a very small andnearly constant value. Next, both plate temperatures arechanged by identical amounts and held at the new temperatureuntil steady state is again achieved. The enthalpy absorbed orreleased by the specimen from the time of the tem
11、peraturechange until steady state is again achieved will be recorded.Using a series of temperature step changes, the cumulativeenthalpy stored or released over a certain temperature range isdetermined.1.6.1 The specific heats of the solid and liquid phases aredetermined from the slope of the sensibl
12、e enthalpy storage asa function of temperature, before and after the phase changeprocess.1.7 Calibration of the HFMA to determine the correctionfactors for the enthalpy stored within the plate heat fluxtransducers and any material placed between the test specimenand the HFMA plates must be performed
13、 following Annex A1.These correction factors are functions of the beginning andending temperatures for each step, as described in Annex A1.1.8 This test method applies to PCMs and composites,products and systems incorporating PCMs, including: dis-persed in, or combined with, a thermal insulation mat
14、erial,boards or membranes containing concentrated or dispersedPCM, etc. Specific examples include solid PCM compositesand products, loose blended materials incorporating PCMs, anddiscretely contained PCM.1.9 This test method may be used to characterize materialproperties, which may or may not be rep
15、resentative of actualconditions of use.1.10 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.11 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is the1This test method is
16、 under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Nov. 1, 2013. Published January 2014. DOI: 10.1520/C1784-13.2The boldface numbers in parentheses refer to the list of references at
17、 the end ofthis standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prio
18、r to use.2. Referenced Documents2.1 ASTM Standards:3C518 Test Method for Steady-State Thermal TransmissionProperties by Means of the Heat Flow Meter ApparatusC168 Terminology Relating to Thermal InsulationE793 Test Method for Enthalpies of Fusion and Crystalliza-tion by Differential Scanning Calorim
19、etryE967 Test Method for Temperature Calibration of Differen-tial Scanning Calorimeters and Differential Thermal Ana-lyzers2.2 Other Standard:RAL-GZ 896 Phase Change Material, Quality AssociationPCM e.V.3. Terminology3.1 DefinitionsTerminology C168 applies to terms used inthis specification.3.2 Defi
20、nitions of Terms Specific to This Standard:3.2.1 phase change material (PCM), na material thatchanges it physical state (solid to liquid or vice-versa) over acertain temperature range, used in engineering applicationsspecifically to take advantage of its latent heat storage proper-ties.3.2.2 PCM Act
21、ive Range, na broad temperature range inwhich a PCM changes phase from solid to liquid (melting) orliquid to solid (freezing), with associated enthalpy changes.3.2.3 PCM composite, nmaterial embedded with PCM toenhance it thermal performance.3.2.4 PCM product, nmaterial amended to include energystor
22、age capabilities via inclusion of PCM or PCM composites.3.2.5 PCM system, narray or assembly of PCM products.3.3 Symbols and UnitsThe symbols used in this testmethod have the following significance:3.3.1 AHFMA metering area, m2.3.3.2 Chft(Tbegin,Tend)correction factor for heat storage inthe heat flu
23、x transducers, J/(m2-C).3.3.3 Cother(Tbegin,Tend)correction factor for heat storagein other materials used to surround the test specimen, J/(m2-C).3.3.4 cp(T)specific heat as a function of temperature,J/kg-C.3.3.5 cpMspecific heat of a melted PCM product, definedat a temperature greater than the upp
24、er limit of the PCMActiveRange, J/kg-C.3.3.6 cpM,Aareal specific heat of a melted PCM product,defined at a temperature greater than the upper limit of thePCM Active Range, J/m2-C.3.3.7 cpM,Vvolumetric specific heat of a melted PCMproduct, defined at a temperature greater than the upper limit ofthe P
25、CM Active Range, J/m3-C.3.3.8 cpFspecific heat of a frozen PCM product, defined ata temperature less than the lower limit of the PCM ActiveRange, J/kg-C.3.3.9 cpF,Aareal specific heat of a frozen PCM product,defined at a temperature less than the lower limit of the PCMActive Range, J/m2-C.3.3.10 cpF
26、,Vvolumetric specific heat of a frozen PCMproduct, defined at a temperature less than the lower limit ofthe PCM Active Range, J/m3-C.3.3.11 Eheat flux transducer output, V.3.3.12 ffraction of total PCM mass in the sample that hasundergone phase change, dimensionless.3.3.13 henthalpy, J/kg.3.3.14 hAa
27、real enthalpy, J/m2.3.3.15 hfslatent heat per unit mass, J/kg.3.3.16 hfs,Alatent heat per unit area, J/m2.3.3.17 hVlatent heat per unit area, J/m2.3.3.18 kthermal conductivity, W/m-K.3.3.19 Lthickness of the test specimen, usually equal tothe separation between the hot and cold plate assemblies duri
28、ngtesting, m.3.3.20 Nnumber of heat flux readings at a specific tem-perature step.3.3.21 qheat flux (heat flow rate, Q, through area A),W/m2.3.3.22 qequilibriumaverage heat flux at the end of a specifictemperature step, W/m2.3.3.23 Qheat flow rate in the metered area, W.3.3.24 Rthermal resistance, (
29、m2K)/W.3.3.25 Scalibration factor of the heat flux transducer,(W/m2)/V.3.3.26 Ttemperature, C.3.3.27 Tbeginbeginning temperature for each temperaturestep, C.3.3.28 Tendending temperature for each temperature step,C.3.3.29 TLlower temperature limit of the PCM ActiveRange, C.3.3.30 TUupper temperature
30、 limit of the PCM ActiveRange, C.3.3.31 Ttemperature difference during a temperaturestep (TendTbegin), C.3.3.32 thermal diffusivity, m2/s.3.3.33 (bulk) density of the material tested, kg/m3.3.3.34 thermal conductivity, W/(mK).3.3.35 time interval, s.3.3.36 time interval corresponding to each individ
31、ualflux reading (data value), s.3.4 Subscripts and Superscripts:3.4.1 Aareal, per m2.3.4.2 Ffrozen, solid.3.4.3 fslatent, associated with the transition from solid toliquid or liquid to solid.3.4.4 i,kindex denoting ith,kthmember of a series.3.4.5 Llower.3For referenced ASTM standards, visit the AST
32、M 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.C1784 1323.4.6 Mmelted, liquid.3.4.7 Uupper.3.4.8 Vvolumetric, per m3.4. Summary of Test Method4.1 This te
33、st method describes a method of using a heat flowmeter apparatus (HFMA) to perform heat flux measurementson samples exposed to dynamic, that is non-steady-state,temperature conditions. The HFMA plates are allowed tostabilize at a certain identical temperature, above or below thePCM Active Range, and
34、 then their temperatures are incremen-tally decreased or increased. The plates are allowed to stabilizeafter each temperature step and the enthalpy change of the testspecimen is determined for each step change in temperature,hence the dynamic nature of the test.NOTE 2Since the dynamic portion of the
35、 test method does notinvolve measurements made under steady-state conditions, nor lead todetermination of steady-state thermal transmission properties, the TestMethod C518 cannot be used.4.1.1 The test method is specifically designed to addressmaterials and products that undergo physical changes wit
36、hlatent heat absorption or release during the course of the test. Inparticular, a phase transition will occur within PCM products,when the test temperatures span the PCM Active Range.4.2 The object of the test, especially for a PCM product, isgenerally to determine the temperature dependence of thee
37、nthalpy storage characteristics of the specimen.5. Significance and Use5.1 Materials used in building envelopes to enhance energyefficiency, including PCM products used for thermal insulation,thermal control, and thermal storage, are subjected to transientthermal environments, including transient or
38、 cyclic boundarytemperature conditions. This test method is intended to enablemeaningful PCM product classification, as steady-state thermalconductivity alone is not sufficient to characterize PCMs.NOTE 3This test method defines a dynamic test protocol for complexproducts or composites containing PC
39、Ms. Due to the macroscopicstructure of these products or composites, conventional measurementsusing a Differential Scanning Calorimeter (DSC) as specified in E793 andE967, which use very small samples, are not representative of therelationship between temperature and enthalpy storage of full-scale P
40、CMproducts due to the sample size limitation.5.2 Dynamic measurements of the thermal performance ofPCM products shall only be performed by qualified personnelwith understanding of heat transfer and error propagation.Familiarity with the configuration of both the apparatus and theproduct is necessary
41、.5.3 This test method focuses on testing PCM products usedin engineering applications, including in building envelopes toenhance the thermal performance of insulation systems.5.3.1 Applications of PCM in building envelopes takemultiple forms, including: dispersed in, or otherwise combinedwith, a the
42、rmal insulation material; a separate object imple-mented in the building envelope as boards or membranescontaining concentrated PCM that operates in conjunction witha thermal insulation material. Both of these forms enhance theperformance of the structure when exposed to dynamic, that is,fluctuating
43、, boundary temperature conditions.5.3.2 PCMs can be studied in a variety of forms: as theoriginal “pure” PCM;asacomposite containing PCM andother embedded materials to enhance thermal performance; asa product containing PCM or composite (such as micro- ormacro-encapsulated PCM); or as a system, comp
44、rising arraysor assemblies of PCM products.5.4 This test method describes a method of using a heat flowmeter apparatus to determine key properties of PCM products,which are listed below. Engineers, architects, modelers, andothers require these properties to accurately predict the in-situperformance
45、of the products (2).5.5 The objective is generally to conduct a test undertemperature conditions that will induce a phase transition (forexample, melting or freezing) in the PCM product during thecourse of the test.5.6 Determination of thermal storage properties is the ob-jective of this test method
46、, and key properties of interestinclude the following:5.6.1 PCM Active Range, that is temperatures over whichthe phase transitions occur, for both melting and freezing of thePCM product or composites containing PCMs.5.6.2 Specific heat of the fully melted and fully frozenproduct, defined outside the
47、 PCM Active Range.5.6.3 Enthalpy change as a function of temperature, h(T),including both sensible and latent components.5.6.4 Enthalpy plota histogram or table that indicates thechange in enthalpy associated with incremental temperaturechanges that span the tested temperature range.5.6.5 Enthalpy o
48、f phase transition during the PCM meltingand freezing processes in materials and composites containingPCMs.5.7 PCM products often possess characteristics that compli-cate measurement and analysis of phase transitions during atest. Following are some of the known issues with PCMs:5.7.1 Imprecise PCM
49、Active RangePCMs in general donot have precise melting or freezing temperatures, and theentire active temperature range, from the beginning to the endof phase transitions, must be determined.NOTE 4The onset of freezing will not necessarily coincide with theend of melting. Therefore, the freeze and melt enthalpy curves must beindependently defined to determine the PCM Active Range.5.7.2 Multiple Phase TransitionsMany PCMs exhibit asolid-solid transition with significant latent heat effects attemper
