1、Designation: C1667 09C1667 15Standard Test Method forUsing Heat Flow Meter Apparatus to Measure the Center-of-Panel Thermal Resistivity Transmission Properties ofVacuum Insulation Panels1This standard is issued under the fixed designation C1667; the number immediately following the designation indic
2、ates 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 measurement of
3、steady-state thermal transmission through the center of a flat rectangularvacuum insulation panel using a heat flow meter apparatus.1.2 Total heat transfer through the non-homogenous geometry of a vacuum insulation panel requires the determination ofseveral factors, as discussed in Specification C14
4、84. One of those factors is the center-of-panel thermal resistivity. Thecenter-of-panel thermal resistivity is an approximation of the thermal resistivity of the core evacuated region.1.3 This test method is based upon the technology of Test Method C518 but includes modifications for vacuum insulati
5、on panelapplications as outlined in this test method.21.4 This test method shall be used in conjunction with Practice C1045 and Practice C1058.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purp
6、ort to address all of the safety concerns, if any, associated with its use. It is the responsibilityof 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:3C168
7、Terminology Relating to Thermal InsulationC518 Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter ApparatusC740 Practice for Evacuated Reflective Insulation In Cryogenic ServiceC1045 Practice for Calculating Thermal Transmission Properties Under Steady-State
8、 ConditionsC1058 Practice for Selecting Temperatures for Evaluating and Reporting Thermal Properties of Thermal InsulationC1484 Specification for Vacuum Insulation PanelsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE177 Practice for Use of the Term
9、s Precision and Bias in ASTM Test Methods3. Terminology3.1 DefinitionsTerminology C168 applies to terms used in this specification.3.2 Definitions of Terms Specific to This Standard:3.2.1 center-of-panelthe location at the center of the largest planar surface of the panel, equidistant from each pair
10、 of oppositeedges of that surface.3.2.2 center-of-panel apparent thermal resistivitythe thermal performance of vacuum insulation panels includes an edge effectdue to heat flow through the barrier material and this shunting of heat around the evacuated volume of the panel becomes more1 This test meth
11、od 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 April 1, 2009Oct. 1, 2015. Published May 2009October 2015. Originally approved in 2007. Last previous edition approved in 20
12、072009 asC166707.09. DOI: 10.1520/C1667-09.10.1520/C1667-15.2 All references to particular sections of Test Method C518 within this document refer to the 20042010 edition of Test Method C518.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at servi
13、ceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. B
14、ecauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 10
15、0 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1prevalent with greater barrier thermal conductivity, as shown in Fig. 1. For panels larger than a minimum size (as described inAnnex A1), the center-of-panel apparent thermal resistivity is a close approximation of the
16、 intrinsic core thermal resistivity of thevacuum insulation panel. The effective thermal performance of a panel will vary with the size and shape of the panel.3.2.2.1 DiscussionThermal resistivity, the reciprocal of apparent thermal conductivity, is used when discussing the center-of-panel thermal b
17、ehavior.3.2.3 corethe material placed within the evacuated volume of a vacuum insulation panel. This material may perform any orall of the following functions: prevent panel collapse due to atmospheric pressure, reduce radiation heat transfer, and reducegas-phase conduction. The apparent thermal con
18、ductivity of the core, or core, is defined as the apparent thermal conductivity ofthe core material under the same vacuum that would occur within a panel, but without the barrier material. This is the apparentthermal conductivity that would be measured in a vacuum chamber without the barrier materia
19、l.3.2.4 effective panel thermal resistance (effective panel R-value)this value reflects the total panel resistance to heat flow,considering heat flow through the evacuated region and through the barrier material. Depending on the thermal conductivity of thebarrier material and the size of the panel,
20、 the effective thermal resistance may be significantly less than the product of thecenter-of-panel apparent thermal resistivity and the panel thickness. The effective thermal resistance is based on the edge-to-edgearea covered by the vacuum insulation panel, that is, the entire panel. The effective
21、thermal resistance will also vary with the panelmean temperature.3.2.4.1 DiscussionThermal resistance, the reciprocal of thermal conductance, is used when discussing the effective thermal performance of the panel.This value includes the effect of the actual panel dimensions, including the panel thic
22、kness.3.2.5 evacuated or vacuum insulationsinsulation systems whose gas phase thermal conductivity portion of the overallapparent thermal conductivity has been significantly reduced by reduction of the internal gas pressure. The level of vacuum willdepend on properties of the composite panel materia
23、ls, and the desired effective panel thermal resistance.43.2.6 panel barrierthe material that envelops the evacuated volume and is used to separate the evacuated volume from theenvironment and to provide a long term barrier to gas and vapor diffusion.4 For further discussion on heat flow mechanisms i
24、n evacuated insulations, see Practice C740 on Evacuated Reflective Insulation in Cryogenic Service.FIG. 1 Side View of a Vacuum Insulation Panel Showing Edge Heat Flow and the Center-of-Panel RegionC1667 1523.2.7 sealany joint between two pieces of barrier material.3.3 Symbols and Units: Abarrier =
25、area of the barrier perpendicular to the largest panel faces, m2Acore = area of the largest panel face covering the core material, m2C = calibration standard conductance, W/m2-KE = heat flux transducer output, VLpanel = panel thickness, mLcalibration standard = thickness of a single layer of the cal
26、ibration standard material, mLcalibration standard, target = target total thickness of the calibration standard material, mq = heat flux through the panel, W/m2Qbarrier = heat flow through the barrier material, WQcenter-of-panel = estimated heat flow at the transducer (as calculated by the model), W
27、Qcore = heat flow through the core region, WRcalibration standard = thermal resistivity of the calibration standard, m-K/WRcenter-of-panel = center of panel thermal resistivity, m-K/WS = calibration factor, (W/m2)/VTc = specimen cold surface temperature, KTh = specimen hot surface temperature, Ktbar
28、rier = thickness of the barrier material, mW1, W2 = panel width, panel length, muc = combined standard uncertaintyun = uncertainty component, for example, standard uncertainty for the measurementZedge = an approximate estimate of the ratio of the heat flow through the barrier material to the heat fl
29、ow through the corematerial, dimensionlessbarrier = thermal conductivity of the barrier material, W/m-Kcore = apparent thermal conductivity of the core region, W/m-K4. Summary of Test Method4.1 This test method describes a modified application of Test Method C518 to evacuated panels. These panels fa
30、ll outside thescope ofTest Method C518, both in their non-homogeneity and in the current lack of specimens having an accepted reference valuethat are of similar size and have the necessary thermal characteristics. Therefore, modifications are necessary in the areas ofapparatus calibration, plate sep
31、aration, test procedures, precision and bias, and reporting.NOTE 1Primary calibration standards, using vacuum insulation panels, have not been prepared for this class of products due to uncertainties abouttheir long-term stability characteristics.5. Significance and Use5.1 Heat flow meter apparatus
32、are being used to measure the center-of-panel portion of a vacuum insulation panel, whichtypically has a very high value of thermal resistivity (that is, equal to or greater than 90 m-K/W). As described in SpecificationC1484, the center-of-panel thermal resistivity is used, along with the panel geom
33、etry and barrier material thermal conductivity, todetermine the effective thermal resistance of the evacuated panel.5.2 Using a heat flow meter apparatus to measure the thermal resistivity of non-homogenous and high thermal resistancespecimens is a non-standard application of the equipment, and shal
34、l only be performed by qualified personnel with understandingof heat transfer and error propagation. Familiarity with the configuration of both the apparatus and the vacuum insulation panelis necessary.5.3 The center-of-panel thermal transmission properties of evacuated panels vary due to the compos
35、ition of the materials ofconstruction, mean temperature and temperature difference, and the prior history. The selection of representative values for thethermal transmission properties of an evacuated panel for a particular application must be based on a consideration of these factorsand will not ap
36、ply necessarily without modification to all service conditions.6. Apparatus6.1 Follow Test Method C518, Section 5 except use Section 88 of this test method for calibration.7. Specimen Preparation7.1 Vacuum insulation panels are typically rigid and the shape cannot be modified for testing purposes. H
37、owever, to obtainrepresentative thermal values for the panel, the two primary surfaces must be parallel and have limited surface irregularities.7.2 If none of the standard product sizes are appropriate for the heat flow meter apparatus used in this test, then representativetest specimens must be pro
38、duced so that they accurately represent both the same average performance as the production productand the same typical product variability.C1667 1537.3 The specimens shall be of the same thickness as the average thickness to be applied in use.7.4 The minimum panel size for this test is determined b
39、y the size of the heat flux transducer in the heat flow meter apparatus,the overall maximum specimen size limit for the apparatus, the thermal conductivity of the barrier, the thickness of the barrier, andthe thermal conductivity of the core. Annex A1 contains a procedure to estimate the minimum acc
40、eptable panel size.7.4.1 Preferably, specimens shall be of such size as to fully cover the plate assembly surfaces, with an allowance of up to 6 mmon each side to allow room for panel seals.7.4.2 If the width or length, or both, of the specimen are smaller than the apparatus compartment, surround th
41、e specimen withhigh thermal resistance insulation. This surrounding material will reduce edge heat transfer and prevent air circulation around thespecimen.7.5 For panels with smooth parallel surfaces, the specimen thickness is represented by the plate separation.7.6 For panels with irregular surface
42、s, to insure thermal contact with the apparatus surfaces, it is necessary to:7.6.1 Measure the panel thickness with an accuracy of 60.05 mm in at least five locations distributed over the surface of thepanel and use the average of the local values. Care shall be taken so that the contact between the
43、 caliper jaws or the length meterspressure foot does not damage the specimen surface.7.6.2 Record the output of one thermocouple placed on the center of the top and one thermocouple placed on the center of thebottom of the panel. The temperatures recorded by the thermocouples, not the hot and cold p
44、late temperatures, shall be used tocalculate the center-of-panel apparent thermal resistivity.7.6.3 Place one sheet (approximately 3 mm thick) of an elastomeric or soft foam rubber between each side of the panel and thecorresponding apparatus plate. This sheet will improve contact between the contro
45、lled temperature plates and prevent aircirculation between the panel and the plates.8. Calibration8.1 The apparatus shall be calibrated according to Test Method C518 sections 6.1 to 6.5.8.2 Specimens having an accepted reference value with physical and thermal characteristics similar to vacuum insul
46、ation panelsare not yet available.The linearity of the heat flux transducers at very low levels of heat flux must be verified using another method.The apparatus calibration must include the addition of at least one of the modified calibration procedures described in 8.5 and 8.6,that is Modified Cali
47、bration Procedure A or B. As described in 8.7, the two modified procedures can be combined if necessary tomeet uncertainty goals. Although each method magnifies an element of experimental error (as discussed below), it is necessary toaugment the standard Test Method C518 calibration for this particu
48、lar application.8.3 It is not intended that the heat flow meter apparatus calibration be altered based on the results of these supplementaryprocedures. Rather the results will be used by qualified personnel (as described in 5.2) to determine whether a particular heat flowmeter apparatus will give me
49、aningful results for a vacuum panel application, and if so, to provide guidance on interpreting andapplying the Test Method C518 test results.NOTE 2Just as with the standard calibration technique, the supplementary calibration need not be repeated for every test if the equipment has beenstable over a significant period of time. See Test Method C518 section 4.5.1.NOTE 3The heat flow meter apparatus may take a long time to reach a true steady-state condition for low conductance specimens, as described inTest Method C518 section 7.7.3.8.4 In order to evaluate the l
