1、Designation: C1784 13C1784 14Standard 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 oforigin
2、al 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 measurement of non-steady-state heat
3、flow into or out of a flat slab specimen to determine thestored energy (that is, enthalpy) change as a function of temperature using a heat flow meter apparatus (HFMA).1.2 In particular, this test method is intended to measure the sensible and latent heat storage capacity for products incorporatingp
4、hase-change materials (PCM).1.2.1 The storage capacity of a PCM is well defined via four parameters: specific heats of both solid and liquid phases, phasechange temperature(s) and phase change enthalpy (1).21.3 To more accurately predict thermal performance, information about the PCM products perfor
5、mance under dynamicconditions is needed to supplement the properties (thermal conductivity) measured under steady-state conditions.NOTE 1This test method defines a dynamic test protocol for products or composites containing PCMs. Due to the macroscopic structure of theseproducts or composites, small
6、 samplespecimen sizes used in conventional Differential Scanning Calorimeter (DSC) measurements, as specified in E793and E967, are not necessarily representative of the relationship between temperature and enthalpy storage of full-scale PCM products.1.4 This test method is based upon the HFMA techno
7、logy used for Test Method C518 but includes modifications for specificheat and enthalpy change measurements for PCM products as outlined in this test method.1.5 Heat flow measurements are required at both the top and bottom HFMA plates for this test method. Therefore, this testmethod applies only to
8、 HFMAs that are equipped with at least one heat flux transducer on each of the two plates and that havethe capability for computerized data acquisition and temperature control systems. Further, the amount of energy flowing throughthe transducers must be measureable at all points in time. Therefore,
9、the transducer output shall never be saturated during a test.1.6 This test method makes a series of measurements to determine the enthalpy thermal energy storage of a test specimen overa temperature range. First, both HFMAplates are held at the same constant temperature until steady state is achieve
10、d. Steady stateis defined by the reduction in the amount of energy entering the specimen from both plates to a very small and nearly constantvalue. Next, both plate temperatures are changed by identical amounts and held at the new temperature until steady state is againachieved. The enthalpyenergy a
11、bsorbed or released by the specimen from the time of the temperature change until steady state isagain achieved will be recorded. Using a series of temperature step changes, the cumulative enthalpy stored or released over acertain temperature range is determined.1.6.1 The specific heats of the solid
12、 and liquid phases are determined from the slope of the sensible enthalpy storage as afunction of temperature, temperature-dependant enthalpy function during sensible heating/cooling, before and after the phasechange process.1.7 Calibration of the HFMA to determine the correction factors for the ent
13、halpyenergy stored within the plate heat fluxtransducers and any material placed between the test specimen and the HFMA plates must be performed following Annex A1.These correction factors are functions of the beginning and ending temperatures for each step, as described in Annex A1.1.8 This test me
14、thod applies to PCMs and composites, products and systems incorporating PCMs, including: dispersedin,including those with PCM dispersed in or combined with,with a thermal insulation material, boards or membranes containingconcentrated or dispersed PCM, etc. Specific examples include solid PCM compos
15、ites and products, loose blended materialsincorporating PCMs, and discretely contained PCM.1 This test method is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Nov. 1, 2013Oct.
16、1, 2014. Published January 2014December 2014. Originally approved in 2013. Last previous edition approved in 2013 asC1784-13. DOI: 10.1520/C1784-13.10.1520/C1784-14.2 The boldface numbers in parentheses refer to the list of references at the end of this standard.This document is not an ASTM standard
17、 and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases on
18、ly the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.9 This test method may be used to characterize material properties, which may or ma
19、y not be representative of actualconditions of use.1.10 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.11 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the resp
20、onsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3C518 Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Met
21、er ApparatusC168 Terminology Relating to Thermal InsulationE793 Test Method for Enthalpies of Fusion and Crystallization by Differential Scanning CalorimetryE967 Test Method for Temperature Calibration of Differential Scanning Calorimeters and Differential Thermal Analyzers2.2 Other Standard:RAL-GZ
22、896 Phase Change Material, Quality Association PCM e.V.3. Terminology3.1 DefinitionsTerminology C168 applies to terms used in this specification.3.2 Definitions of Terms Specific to This Standard:3.2.1 phase change material (PCM), na material that changes it physical state (solid to liquid or vice-v
23、ersa) over a certaintemperature range, used in engineering applications specifically to take advantage of its latent heat storage properties.3.2.2 PCM Active Range, na broad temperature range in which a PCM changes phase from solid to liquid (melting) or liquidto solid (freezing), with associated en
24、thalpy changes.3.2.3 PCM composite, nmaterial embedded with PCM to enhance itits thermal performance.3.2.4 PCM product, nmaterial amended to include energy storage capabilities via inclusion of PCM or PCM composites.3.2.5 PCM system, narray or assembly of PCM products.3.3 Symbols and UnitsThe symbol
25、s used in this test method have the following significance:3.3.1 AHFMA metering area, m2.3.3.2 Chft(Tbegin,Tend)correction factor for heat storage in the heat flux transducers, J/(m2-C).3.3.3 Cother(Tbegin,Tend)correction factor for heat storage in other materials used to surround the test specimen,
26、 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, defined at a temperature greater than the upper limit of the PCM ActiveRange, J/kg-C.3.3.6 cpM,Aareal specific heat of a melted PCM product, defined at a temperature greater than t
27、he upper limit of the PCMActive Range, J/m2-C.3.3.7 cpM,Vvolumetric specific heat of a melted PCM product, defined at a temperature greater than the upper limit of the PCMActive Range, J/m3-C.3.3.8 cpFspecific heat of a frozen PCM product, defined at a temperature less than the lower limit of the PC
28、M Active Range,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 PCM ActiveRange, J/m2-C.3.3.10 cpF,Vvolumetric specific heat of a frozen PCM product, defined at a temperature less than the lower limit of the PCMActive Range, J/m
29、3-C.3.3.11 Eheat flux transducer output, V.3.3.12 ffraction of total PCM mass in the sample that has undergone phase change, dimensionless.3.3.13 henthalpy, J/kg.3.3.14 hAareal 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 p
30、er unit area, J/m2.3.3.18 kthermal conductivity, W/m-K.3.3.19 Lthickness of the test specimen, usually equal to the separation between the hot and cold plate assemblies duringtesting, m.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceast
31、m.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.C1784 1423.3.20 Nnumber of heat flux readings at a specific temperature step.3.3.21 qheat flux (heat flow rate, Q, through area A), W/m2.3.3.22 qequilibriumaverage heat flux a
32、t the end of a specific temperature step, W/m2.3.3.23 Qheat flow rate in the metered area, W.3.3.24 Rthermal resistance, (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 temperature step, C.3.3.28 Tendending t
33、emperature for each temperature step, C.3.3.29 TLlower temperature limit of the PCM Active Range, C.3.3.30 TUupper temperature limit of the PCM Active Range, C.3.3.31 Ttemperature difference during a temperature step (Tend Tbegin), C.3.3.32 thermal diffusivity, m2/s.3.3.33 (bulk) density of the mate
34、rial tested, kg/m3.3.3.34 thermal conductivity, W/(mK).3.3.35 time interval, s.3.3.36 time interval corresponding to each individual flux 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 to liq
35、uid or liquid to solid.3.4.4 i,kindex denoting ith, kth member of a series.3.4.5 Llower.3.4.6 Mmelted, liquid.3.4.7 Uupper.3.4.8 Vvolumetric, per m3.4. Summary of Test Method4.1 This test method describes a method of using a heat flow meter apparatus (HFMA) to perform heat flux measurements onsample
36、s exposed to dynamic, that is non-steady-state, temperature conditions.The HFMAplates are allowed to stabilize at a certainidentical temperature, above or below the PCM Active Range, and then their temperatures are incrementally decreased orincreased.The plates are allowed to stabilize after each te
37、mperature step and the enthalpy change of the test specimen is determinedfor each step change in temperature, hence the dynamic nature of the test.NOTE 2Since the dynamicportion of the test method does not involve measurements made under steady-state conditions, nor lead to determinationof steady-st
38、ate thermal transmission properties, the Test Method C518 cannot be used.4.1.1 The test method is specifically designed to address materials and products that undergo physical changes with latent heatabsorption or release during the course of the test. In particular, a phase transition will occur wi
39、thin PCM products, when the testtemperatures span the PCM Active Range.4.2 The object of the test, especially for a PCM product, is generally to determine the temperature dependence of the enthalpystorage characteristics of the specimen.5. Significance and Use5.1 Materials used in building envelopes
40、 to enhance energy efficiency, including PCM products used for thermal insulation,thermal control, and thermal storage, are subjected to transient thermal environments, including transient or cyclic boundarytemperature conditions. This test method is intended to enable meaningful PCM product classif
41、ication, as steady-state thermalconductivity alone is not sufficient to characterize PCMs.NOTE 3This test method defines a dynamic test protocol for complex products or composites containing PCMs. Due to the macroscopic structureof these products or composites, conventional measurements using a Diff
42、erential Scanning Calorimeter (DSC) as specified in E793 and E967, which usevery small samples,specimens, are not necessarily representative of the relationship between temperature and enthalpy storage of full-scale PCM productsdue to the samplespecimen size limitation.5.2 Dynamic measurements of th
43、e thermal performance of PCM products shall only be performed by qualified personnel withunderstanding of heat transfer and error propagation. Familiarity with the configuration of both the apparatus and the product isnecessary.5.3 This test method focuses on testing PCM products used in engineering
44、 applications, including in building envelopes toenhance the thermal performance of insulation systems.5.3.1 Applications of PCM in building envelopes take multiple forms, including: dispersed in, or otherwise combined with, athermal insulation material; a separate object implemented in the building
45、 envelope as boards or membranes containingC1784 143concentrated PCM that operates in conjunction with a thermal insulation material. Both of these forms enhance the performanceof the structure when exposed to dynamic, that is, fluctuating, boundary temperature conditions.5.3.2 PCMs can be studied i
46、n a variety of forms: as the original “pure” PCM; as a composite containing PCM and otherembedded materials to enhance thermal performance; as a product containing PCM or composite (such as micro- ormacro-encapsulated PCM); or as a system, comprising arrays or assemblies of PCM products.5.4 This tes
47、t method describes a method of using a heat flow meter apparatus to determine key properties of PCM products,which are listed below. Engineers, architects, modelers, and others require these properties to accurately predict the in-situperformance of the products (2).5.5 The objective is generally to
48、 conduct a test under temperature conditions that will induce a phase transition (for example,melting or freezing) in the PCM product during the course of the test.5.6 Determination of thermal storage properties is the objective of this test method, and key properties of interest include thefollowin
49、g:5.6.1 PCM Active Range, that is temperatures the temperature interval over which the phase transitions occur, for both meltingand freezing of the PCM product or composites containing PCMs.5.6.2 Specific heat of the fully melted and fully frozen product, defined outside the PCM Active Range.5.6.3 Enthalpy change as a function of temperature, h(T),h(T). including both sensible and latent components.5.6.4 Enthalpy plotEnthalpy plota a histogram or table that indicates the change in enthalpy asso
