1、Designation: C1774 13Standard Guide forThermal Performance Testing of Cryogenic InsulationSystems1This standard is issued under the fixed designation C1774; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 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 guide provides information for the laboratorymeasurement of the steady-state thermal transmission proper-ties and heat flux of
3、thermal insulation systems under cryo-genic conditions. Thermal insulation systems may be com-posed of one or more materials that may be homogeneous ornon-homogeneous; flat, cylindrical, or spherical; at boundaryconditions from near absolute zero or4Kupto400K;andinenvironments from high vacuum to an
4、 ambient pressure of airor residual gas. The testing approaches presented as part of thisguide are distinct from, and yet complementary to, otherASTM thermal test methods including C177, C518, and C335.Akey aspect of this guide is the notion of an insulation system,not an insulation material. Under
5、the practical use environmentof most cryogenic applications even a single-material systemcan still be a complex insulation system (1-3).2To determinethe inherent thermal properties of insulation materials, thestandard test methods as cited in this guide should be con-sulted.1.2 The function of most
6、cryogenic thermal insulationsystems used in these applications is to maintain large tem-perature differences thereby providing high levels of thermalinsulating performance. The combination of warm and coldboundary temperatures can be any two temperatures in therange of near0Kto400K.Cold boundary tem
7、peraturestypically range from4Kto100K,butcanbemuch highersuch as 300 K. Warm boundary temperatures typically rangefrom 250 K to 400 K, but can be much lower such as 40 K.Large temperature differences up to 300 K are typical. Testingfor thermal performance at large temperature differences withone bou
8、ndary at cryogenic temperature is typical and repre-sentative of most applications. Thermal performance as afunction of temperature can also be evaluated or calculated inaccordance with Practices C1058 or C1045 when sufficientinformation on the temperature profile and physical modelingare available.
9、1.3 The range of residual gas pressures for this Guide isfrom 10-7torr to 10+3torr (1.33-5Pa to 133 kPa) with differentpurge gases as required. Corresponding to the applications incryogenic systems, three sub-ranges of vacuum are also de-fined: High Vacuum (HV) from 10-6torr to 10-3torr (1.333-4Pa t
10、o 0.133 Pa) free molecular regime, Soft Vacuum (SV)from 10-2torr to 10 torr (from 1.33 Pa to 1,333 Pa) transitionregime, No Vacuum (NV) from 100 torr to 1000 torr (13.3 kPato 133 kPa) continuum regime.1.4 Thermal performance can vary by four orders of mag-nitude over the entire vacuum pressure range
11、. Effective thermalconductivities can range from 0.010 mW/m-K to 100 mW/m-K. The primary governing factor in thermal performance isthe pressure of the test environment. High vacuum insulationsystems are often in the range from 0.05 mW/m-K to 2mW/m-K while non-vacuum systems are typically in the rang
12、efrom 10 mW/m-K to 30 mW/m-K. Soft vacuum systems aregenerally between these two extremes (4). Of particular de-mand is the very low thermal conductivity (very high thermalresistance) range in sub-ambient temperature environments.For example, careful delineation of test results in the range of0.01 m
13、W/m-K to 1 mW/m-K (from R-value 14,400 to R-value144) is required as a matter of normal engineering applicationsfor many cryogenic insulation systems (5-7). The applicationof effective thermal conductivity values to multilayer insula-tion (MLI) systems and other combinations of diversematerials, bec
14、ause they are highly anisotropic and specialized,must be done with due caution and full provision of supportingtechnical information (8). The use of heat flux (W/m2) is, ingeneral, more suitable for reporting the thermal performance ofMLI systems (9-11).1.5 This guide covers different approaches for
15、 thermalperformance measurement in sub-ambient temperature envi-ronments. The test apparatuses (apparatus) are divided into twocategories: boiloff calorimetry and electrical power. Bothabsolute and comparative apparatuses are included.1.6 This guide sets forth the general design requirementsnecessar
16、y to construct and operate a satisfactory test apparatus.1This test method is 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 February 2014. DOI: 10.1520/C1
17、774-13.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1A wide variety of apparatus constructions, test conditions, andoperating conditions
18、 are covered. Detailed designs are notgiven but must be developed within the constraints of thegeneral requirements. Examples of different cryogenic testapparatuses are found in the literature (12). These apparatusesinclude boiloff types (13-17) as well as electrical types (18-21).1.7 These testing
19、approaches are applicable to the measure-ment of a wide variety of specimens, ranging from opaquesolids to porous or transparent materials, and a wide range ofenvironmental conditions including measurements conductedat extremes of temperature and with various gases and over arange of pressures. Of p
20、articular importance is the ability totest highly anisotropic materials and systems such as multilayerinsulation (MLI) systems (22-25). Other test methods arelimited in this regard and do not cover the testing of MLI andother layered systems under the extreme cryogenic and vacuumconditions that are
21、typical for these systems.1.8 In order to ensure the level of precision and accuracyexpected, users applying this standard must possess a workingknowledge of the requirements of thermal measurements andtesting practice and of the practical application of heat transfertheory relating to thermal insul
22、ation materials and systems.Detailed operating procedures, including design schematicsand electrical drawings, should be available for each apparatusto ensure that tests are in accordance with this Guide. Inaddition, automated data collecting and handling systemsconnected to the apparatus must be ve
23、rified as to theiraccuracy. Verification can be done by calibration and compar-ing data sets, which have known results associated with them,using computer models.1.9 It is impractical to establish all details of design andconstruction of thermal insulation test equipment and toprovide procedures cov
24、ering all contingencies associated withthe measurement of heat flow, extremely delicate thermalbalances, high vacuum, temperature measurements, and gen-eral testing practices. The user may also find it necessary, whenrepairing or modifying the apparatus, to become a designer orbuilder, or both, on w
25、hom the demands for fundamentalunderstanding and careful experimental technique are evengreater. The test methodologies given here are for practical useand adaptation as well as to enable future development ofimproved equipment or procedures.1.10 This guide does not specify all details necessary for
26、 theoperation of the apparatus. Decisions on sampling, specimenselection, preconditioning, specimen mounting andpositioning, the choice of test conditions, and the evaluation oftest data shall follow applicable ASTM Test Methods, Guides,Practices or Product Specifications or governmental regula-tion
27、s. If no applicable standard exists, sound engineeringjudgment that reflects accepted heat transfer principles must beused and documented.1.11 This guide allows a wide range of apparatus design anddesign accuracy to be used in order to satisfy the requirementsof specific measurement problems. Compli
28、ance with a furtherspecified test method should include a report with a discussionof the significant error factors involved as well the uncertaintyof each reported variable.1.12 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.
29、Either SI or Imperial units may be used in the report,unless otherwise specified.1.13 Safety precautions including normal handling andusage practices for the cryogen of use. Prior to operation of theapparatus with any potentially hazardous cryogen or fluid, acomplete review of the design, constructi
30、on, and installation ofall systems shall be conducted. Safety practices and proceduresregarding handling of hazardous fluids have been extensivelydeveloped and proven through many years of use. For systemscontaining hydrogen, particular attention shall be given toensure the following precautions are
31、 addressed: (1) adequateventilation in the test area, (2) prevention of leaks, (3)elimination of ignition sources, (4) fail safe design, and (5)redundancy provisions for fluid fill and vent lines. Thisstandard does not purport to address all of the safety concerns,if any, associated with its use. It
32、 is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.1.14 Major sections within this standard are arranged asfollows:SectionScope 1Referenced Documents 2Terminology 3Summary of T
33、est Methods 4Significance and Use 5Apparatus 6Test Specimens and Preparation 7Procedure 8Calculation of Results 9Report 10Keywords 11AnnexesCylindrical Boiloff Calorimeter (Absolute) Annex A1Cylindrical Boiloff Calorimeter (Comparative) Annex A2Flat Plate Boiloff Calorimeter (Absolute) Annex A3Flat
34、Plate Boiloff Calorimeter (Comparative) Annex A4Electrical Power Cryostat Apparatus (Cryogen) Annex A5Electrical Power Cryostat Apparatus (Cryocooler) Annex A6AppendixRationale Appendix X1References2. Referenced Documents2.1 ASTM Standards:3C167 Test Methods for Thickness and Density of Blanket orBa
35、tt Thermal InsulationsC168 Terminology Relating to Thermal InsulationC177 Test Method for Steady-State Heat Flux Measure-ments and Thermal Transmission Properties by Means ofthe Guarded-Hot-Plate ApparatusC335 Test Method for Steady-State Heat Transfer Propertiesof Pipe InsulationC518 Test Method fo
36、r Steady-State Thermal TransmissionProperties by Means of the Heat Flow Meter Apparatus3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summar
37、y page onthe ASTM website.C1774 132C520 Test Methods for Density of Granular Loose FillInsulationsC534 Specification for Preformed Flexible Elastomeric Cel-lular Thermal Insulation in Sheet and Tubular FormC549 Specification for Perlite Loose Fill InsulationC552 Specification for Cellular Glass Ther
38、mal InsulationC578 Specification for Rigid, Cellular Polystyrene ThermalInsulationC591 Specification for Unfaced Preformed Rigid CellularPolyisocyanurate Thermal InsulationC680 Practice for Estimate of the Heat Gain or Loss and theSurface Temperatures of Insulated Flat, Cylindrical, andSpherical Sys
39、tems by Use of Computer ProgramsC740 Practice for Evacuated Reflective Insulation In Cryo-genic ServiceC870 Practice for Conditioning of Thermal Insulating Ma-terialsC1029 Specification for Spray-Applied Rigid Cellular Poly-urethane Thermal InsulationC1045 Practice for Calculating Thermal Transmissi
40、on Prop-erties Under Steady-State ConditionsC1058 Practice for Selecting Temperatures for Evaluatingand Reporting Thermal Properties of Thermal InsulationC1482 Specification for Polyimide Flexible Cellular Ther-mal and Sound Absorbing InsulationC1484 Specification for Vacuum Insulation PanelsC1594 S
41、pecification for Polyimide Rigid Cellular ThermalInsulationC1667 Test Method for Using Heat Flow MeterApparatus toMeasure the Center-of-Panel Thermal Resistivity ofVacuum PanelsC1728 Specification for Flexible Aerogel InsulationE230 Specification and Temperature-Electromotive Force(EMF) Tables for S
42、tandardized ThermocouplesE408 Test Methods for Total Normal Emittance of SurfacesUsing Inspection-Meter TechniquesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:4ISO 21014 Cryogenic Vessels: Cryogenic Insulation Perfor-mance3. Termino
43、logy3.1 DefinitionsTerminology of standards C168, C680, andC1045 applies to the terms used in this standard unlessotherwise noted. Properties based on specimens tested underthe conditions specified may not be representative of theinstalled performance if the end use conditions differ substan-tially
44、from the test conditions. The temperature dependences ofthe thermal performance of a given insulation test specimen,particularly those at large temperature differentials that arecommon to most cryogenic insulation systems, are generallyexpected to be significant and non-linear in nature. For details
45、on testing or analysis in the thermal characterization of aspecific material, C1045, Section 6, Determination of theThermal Conductivity Relationship for a Temperature Range,should be consulted.3.2 Definitions:3.2.1 cryogenic insulation systemsencompass a widerange of material combinations and therm
46、al performancelevels. Examples of the effective thermal conductivity ofdifferent systems and the widely varying thermal performanceranges are shown in Fig. 1.3.2.2 insulation test specimenan insulation test specimenis composed of one or more materials, homogeneous ornon-homogeneous, for which therma
47、l transmission propertiesthrough the thickness of the system are to be measured undersub-ambient conditions.3.2.2.1 DiscussionAn insulation test specimen may con-sist of a single material, one type of material in several discreteelements, or a number of different materials working in aspecialized de
48、sign configuration. In reality, a test specimen isalways a system, either a single material (with or withoutinclusion of a gas) or a combination of materials in differentforms. Forms of insulation test specimens may be bulk-fill,powder, blanket, layered, clam-shell, panels, monoliths, orother type c
49、onfigurations. Examples of materials include foams(closed cell or open cell), fibrous insulation products, aerogels(blankets or bulk-fill or packaged), multilayer insulationsystems, clam shells of foams of cellular glass, compositepanels, polymeric composites, or any number of bulk-fillmaterials such as perlite powder and glass bubbles.3.2.3 multilayer insulation (MLI)insulation systems com-posed of multiple radiation shields physically separated toreduce conductive heat transfer. The radiation shields are thinplastic membranes (usually polyester or polyimide films)coated o
