CEN TR 14613-2003 Thermal performance of building materials and components C Principles for the determination of thermal properties of moist materials and components《建筑材料和组件的热性能 潮湿.pdf

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1、PUBLISHED DOCUMENTPD CEN/TR 14613:2003Thermal performance of building materials and components Principles for the determination of thermal properties of moist materials and componentsThe European Standard CEN/TR 14613:2003 has the status of a British StandardICS 91.100.01; 91.120.10g49g50g3g38g50g51

2、g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58PD CEN/TR 14613:2003This Published Document was published under the authority of the Standards Policy and Strategy Co

3、mmittee on 12 December 2005 BSI 12 December 2005ISBN 0 580 47345 7National forewordThis Published Document is the official English language version of CEN/TR 14613:2003.The UK participation in its preparation was entrusted to Technical Committee B/540, Energy performance of materials, components and

4、 buildings, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue u

5、nder the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct ap

6、plication. Compliance with a Published Document does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; m

7、onitor related international and European developments and promulgate them in the UK.Summary of pagesThis document comprises a front cover, an inside front cover, the CEN/TR title page, pages 2 to 29 and a back cover.The BSI copyright notice displayed in this document indicates when the document was

8、 last issued.Amendments issued since publicationAmd. No. Date CommentsTECHNICAL REPORTRAPPORT TECHNIQUETECHNISCHER BERICHTCEN/TR 14613December 2003ICS 91.100.01; 91.120.10English versionThermal performance of building materials and components Principles for the determination of thermal properties of

9、 moistmaterials and componentsPerformances thermiques des matriaux et composantspour le btiment Principes pour la dtermination desproprits thermiques des matriaux et composantshumidesThis Technical Report was approved by CEN on 24 July 2003. It has been drawn up by the Technical Committee CEN/TC 89.

10、CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and UnitedKingdom.EUROPEAN COMMITTEE FOR STANDARDIZATI

11、ONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2003 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. CEN/TR 14613:2003 E2ContentsPageForeword3Introduction .41 Backgrou

12、nd 41.1 General41.2 Needs related to standardisation .41.3 Scope of this technical report 52 References53 Terms, definitions, symbols and units 63.1 Terms and definitions63.2 Symbols and units .64 Moisture effects on heat transfer .65 Measurement procedures, dry material.76 Measurement procedures, m

13、oist material.86.1 Introduction 86.2 Conditioning.86.3 Errors due to moisture redistribution96.3.1 General96.3.2 Moisture movement small enough to neglect effects of phase changes 96.3.3 Measurements at moisture equilibrium.157 Measurement procedures Effects of moisture in hot box measurements .187.

14、1 Background 187.2 Determination of R* in a hot box 197.3 Estimation of errors due to moisture.19Annex A (informative) Estimation of stabilization time 21Annex B (informative) Experimental determination of moisture distribution 24Annex C (informative) A method for the theoretical estimation of the m

15、oisture distribution26Annex D (informative) A method of calculation ll * at moisture equilibrium.27Annex E (informative) Some basic equations for heat and moisture transfer used in this technicalreport.28CEN/TR 14613:20033ForewordThis document (CEN/TR 14613:2003) has been prepared by Technical Commi

16、ttee CEN /TC 89 “Thermalperformance of buildings and building components“, the secretariat of which is held by SIS.Annexes A, B, C, D and E are informative.CEN/TR 14613:20034Introduction1 Background1.1 GeneralCEN/TC 89/WG 8 has developed standards for determination of thermal properties of various m

17、asonry materialsused in building envelopes, e.g. brick and lightweight concrete. In the work, considerable effort has been put intothe development of methods of testing moist materials and estimating the errors in such measurements. This reportdescribes some of the background material that has been

18、developed as part of the standardisation work and whichhas provided a basis for formulation of the standards.In this report it is assumed that the thermal properties are being determined using hot plate, heat flow meter or hotbox apparatus and steady state conditions in accordance withEN 12664, Ther

19、mal performance of building materials and products Determination of thermal resistance bymeans of guarded hot plate and heat flow meter methods Dry and moist products of medium and lowthermal resistance;EN ISO 8990, Thermal insulation Determination of steady-state thermal transmission properties Cal

20、ibratedand guarded hot box (ISO 8990:1994);EN 1934, Thermal performance of buildings Determination of thermal resistance by hot box method usingheat flow meter Masonry.1.2 Needs related to standardisationIn the future European system for the design of thermal performance of buildings, the declared t

21、hermal value andthe design thermal values are of special importance.declared thermal valueexpected value of a thermal property of a building material or product- assessed from measured data at reference conditions of temperature and humidity;- given for a stated fraction and confidence level;- corre

22、sponding to a reasonable expected service lifetime under normal conditionsThere is consequently a need to have a method to determine the hygrothermal transmissivity, l *, at a moisturecontent corresponding to the reference condition of humidity. An alternative could be to determine l * at severaloth

23、er moisture contents (including dry) and establish a relationship for conversion to reference moisture content.design thermal valuevalue of thermal property of a building material or product under specific external and internal conditions whichcan be considered as typical of the performance of that

24、material or product when incorporated in a buildingcomponentDetermination of the design value requires knowledge of the relationship between l * and moisture content andabout expected moisture contents and movements under service conditions.Measurements on moist materials are complicated and time-co

25、nsuming. Therefore these measurements are notnormally routine measurements but performed at special occasions to establish the necessary relationships foreach material, product or building component.CEN/TR 14613:200351.3 Scope of this technical reportThe theoretical background for the effects of moi

26、sture on heat transfer, which is given here, is valid for all types ofmaterials, but the applications and detailed guidelines have been developed with a specific type of material in mind:masonry with medium or high thermal conductivity, the physical characteristics of which can be roughly expresseda

27、s follows:hygrothermal transmissivity l * 0,10 W/(m K)vapour permeability dv10 kg/m3(between 50 % RH and 80 % RH)(“hygroscopicity”)This document is restricted to moisture contents in the hygroscopic range, where moisture content is in equilibriumwith 95 % relative humidity or lower. For most buildin

28、g materials, moisture content in equilibrium with air having upto 95 % relative humidity is usually below the threshold value where the flow of liquid takes place. This value isoften called critical saturation, when expressed as the fraction of voids with liquid, or critical moisture content whenexp

29、ressed as a specific moisture content. For higher moisture contents, reference is made to ISO 10051.Preferred moisture contents are:a) in equilibrium with 50 % relative humidity (due to the requirements in the material specifications);b) in equilibrium with 80 % relative humidity (because this level

30、 is sometimes considered as “the practicalmoisture content“).2 ReferencesEN 1934, Thermal performance of buildings Determination of thermal resistance by hot box method using heatflow meter Masonry.EN 12429, Thermal insulation products for building applications Conditioning to moisture equilibrium u

31、nderspecified temperature and humidity conditions.EN 12664, Thermal performance of building materials and products Determination of thermal resistance bymeans of guarded hot plate and heat flow meter methods Dry and moist products of medium and low thermalresistance.EN ISO 8990, Thermal insulation D

32、etermination of steady-state thermal transmission properties Calibrated andguarded hot box (ISO 8990:1994).EN ISO 10456, Building materials and products Procedures for determining declared and design thermal values(ISO 10456:1999).ISO 10051, Thermal insulation Moisture effects on heat transfer Deter

33、mination of thermal transmissivity of amoist material.CEN/TR 14613:200363 Terms, definitions, symbols and units3.1 Terms and definitionsFor the purposes of this CEN Technical report the terms and definitions in EN 12664 apply.3.2 Symbols and unitsSymbol Quantity UnitDwmoisture diffusivity m2/sR ther

34、mal resistancem2K/WR* thermal resistance of a moist componentm2K/WT thermodynamic temperature Kg density of moisture flow ratekg/(m2s)gvdensity of vapour flow rate kg/(m2s)hespecific latent enthalpy of evaporation or condensation W s/kgl half specimen thickness mp partial vapour pressure Pat time su

35、 moisture content mass by mass kg/kgv humidity by volume kg/m3vsathumidity by volume at saturation kg/m3w moisture content mass by volume kg/m3dpvapour permeability with regard to partial vapour pressure kg/(m s Pa)dvvapour permeability with regard to humidity by volume m2/sx moisture differential c

36、apacity, dw/dj kg/m3l thermal conductivity (at dry state) W(m K)l * hygrothermal transmissivity W/(m K)j relative humidity -4 Moisture effects on heat transferWhen discussing moisture effects on heat transfer it is convenient to divide the density of heat flow rate into threecomponents:a) Heat flow

37、caused by a temperature gradient in a condition of moisture equilibrium i.e. no moisture transfer:xTqdd*al-= (1)l *, the hygrothermal transmissivity (thermal conductivity of a moist material), is an intrinsic material propertydepending on moisture content.CEN/TR 14613:20037b) Convective heat transfe

38、r by moisture flow. The water and water vapour carry their respective enthalpies. Thiscomponent is normally negligible.c) Heat transfer due to phase changes. This effect depends entirely on the occurrence and magnitude ofmoisture transfer in the material. To determine this component it is necessary

39、to know the moisturemovements.The determination of l * is described in ISO 10051. For the purpose of developing a strategy for masonry materials,relevant parts have been extracted from ISO 10051 and in some cases simplified or further elaborated.5 Measurement procedures, dry materialMeasurements on

40、moist materials are complicated and time-consuming. Therefore, routine measurements shall, asfar as possible, be carried out on dry materials. General rules are set down in EN 12664.The test specimen shall be dried to constant mass in a ventilated oven at 105 C to 110 C that takes the air froman env

41、ironment at (23 2) C and (50 5) % relative humidity. Constant mass is considered to have beenestablished when the change of mass during 24 h is less than 0,1 % of the total mass. For thick specimens (0,1 m) a more strict criterion may be needed. The background for the constant mass criterion is give

42、n in annex A.After the drying, the test specimen shall be enclosed in a vapour-tight envelope. The reason for this is primarily toprevent moisture from entering the specimen, condensing in the cold parts of the specimen and thus affecting thedensity of heat flow rate and temperature distribution. Co

43、nsider a test under the following conditions:The density of sensible heat flow rate is()4005,002010,0 =-=q W/m2(2)Assuming that an acceptable density of latent heat flow rate is 1 % of the density of sensible heat flow rate (whichis 0,4 W/m2), then we have the following equation:4,0e=hg (3)whereg is

44、 the rate of moisture accumulation, in kg/(m2 x s);heis the specific enthalpy of condensation (at 10 C) 2480 103J/kg;from which g is calculated73106,11024804,0-=g kg/(m2x s) (4)By dividing by the thickness of the test specimen we get the change in moisture content per time (hour)01,005,03600106,1dd7

45、=-twkg/(m3x h) (5)Most of the moisture accumulation will take place in the guard zone and therefore a requirement20 C0 C0,05 ml = 0,10 W/(m K)qgCEN/TR 14613:2003801,0ddtwkg/(m3x h) (6)is considered reasonable and on the safe side.The envelope shall consequently be impermeable enough to prevent a cha

46、nge in moisture content larger than0,01 kg/(m3x h).The mass of the specimen shall be measured before and after the test, to determine the relative mass changes.A vapour-tight envelope may be omitted if the moisture accumulation in the test specimen during the test is knownto be lower than 0,01 kg/(m

47、3x h) and no visible condensation occurs on the cold plate.NOTE The vapour-tight envelope can change the contact resistance and special precaution should be taken to measurecorrect surface temperatures.6 Measurement procedures, moist material6.1 IntroductionDetermination of l * always requires a tem

48、perature gradient. Normally this causes a redistribution of the moisture inthe material, which leads to two types of problems:a) Redistribution of the moisture. This means that the test is carried out on a specimen with a moisturedistribution, which is no longer uniform. The lower the temperature gr

49、adient, the lower the rate of distribution.The recommendation is consequently not to use an unnecessarily high temperature gradient or long durationof the test.b) Redistribution of the moisture simultaneously induces phase changes (latent heat effects). These effects haveto be well known or negligible during the test. Otherwise it is not possible to determine l *.Observe that using small temperature gradients does not guarantee that phase-change effects will benegligible.There are three options to deal with these problems:1)