1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 1934:1998 The Europ
2、ean Standard EN 1934:1998 has the status of a British Standard ICS 91.120.10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Thermal performance of buildings Determination of thermal resistance by hot box method using heat flow meter MasonryThis British Standard, having been p
3、repared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 July 1998 BSI 1998 ISBN 0 580 29671 7 BS EN 1934:1998 Amendments issued since publication Amd. No. Date Text affected National foreword This British Stand
4、ard is the English language version of EN 1934:1998. The UK participation in its preparation was entrusted by Technical Committee RHE/9, Thermal insulating materials, to Subcommittee RHE/9/2, Thermal properties of insulating materials, which has the responsibility to: aid enquirers to understand the
5、 text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can b
6、e obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “F
7、ind” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from leg
8、al obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 17 and a back cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart, 36 B-
9、1050 Brussels 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1934:1998 E EUROPEAN STANDARD EN 1934 NORME EUROPE ENNE EUROPA ISCHE NORM March 1998 ICS 91.060.10; 91.080.30; 91.120.10 Descriptors: Buildings, walls, laboratory t
10、ests, measurements, thermal properties, thermal resistance, heat transfer, fidelity calibration English version Thermal performance of buildings Determination of thermal resistance by hot box method using heat flow meter Masonry Performance thermique des ba timents De termination de la re sistance t
11、hermique selon la me thode de la bo te chaude avec fluxme tre Maonnerie Wa rmetechnisches Verhalten von Geba uden Messung des Wa rmedurchlawiderstandes Heizkastenverfahren mit dem Wa rmestrommesser Mauerwerk This European Standard was approved by CEN on 24 January 1998. CEN members are bound to comp
12、ly with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Sec
13、retariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the off
14、icial versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 1934:1998 BSI 1998 Foreword This E
15、uropean Standard has been prepared by Technical Committee CEN/TC 89, Thermal performance of buildings and building components, the Secretariat of which is held by SIS. This European Standard is one of a package on measurements with hot box apparatus. The basic principles of the method and the guarde
16、d and calibrated implementations are described in EN ISO 8990. In this European Standard the basic principles of the method and the implementation of a heat flow meter in a hot box for measurements on masonry is described, keeping the style and structure as similar as possible to EN ISO 8990:1996. T
17、he numbering of clauses in this European Standard follows the clause numbering in EN ISO 8990:1996. In the same package of European Standards the procedure to test window panes, window frames, complete windows and doors in a hot box are described. This European Standard shall be given the status of
18、a national standard, either by publication of an identical text or by endorsement, at the latest by September 1998, and conflicting national standards shall be withdrawn at the latest by September 1998. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the fo
19、llowing countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Contents Page Foreword 2 Introduction 3
20、 1 Scope 3 2 Normative references 3 3 Definitions, symbols and units 4 4 Principle of the method 4 5 Limitations and sources of errors 6 6 Apparatus design 7 7 Performance evaluation and calibration 12 8 Test procedure 13 9 Accuracy and reproducibility 14 10 Test report 15 Annex A (normative) Calibr
21、ation of heat flow meters 16 Annex B (informative) Bibliography 17Page 3 EN 1934:1998 BSI 1998 Introduction Many masonry elements are such that in practice the heat transfer through them is a complex combination of conduction, convection, radiation and mass transfer. The method described in this sta
22、ndard determines the total amount of heat transferred from one side of the specimen to the other for a given temperature difference in defined testing conditions. However, the heat transfer properties often depend on the specimen itself and on the boundary conditions, specimen dimensions, direction
23、of heat transfer, temperatures, temperature differences, air velocities and relative humidity. In consequence the test conditions either replicate those of the intended application or are convertible to them. For ease of intercomparison of results, conventional testing conditions are adopted during
24、the tests. Tested values are the base used in conversion procedures to get the appropriate design values. The results obtained from a single specimen are not necessarily representative or applicable to all samples of a masonry wall and product standards should be consulted for appropriate sampling.
25、The design and operation of the heat flow meter hot box is a very complex subject. It is essential that the designer and user of such apparatus has a thorough background knowledge of heat transfer, and has experience of precision measurement techniques. For a particular specimen it should be decided
26、 whether the method is applicable or whether other measurement methods or calculations are more suitable. For homogeneous specimens the guarded hot plate apparatus (see ISO 8302) or the heat flow meter apparatus (see ISO 8301) should be preferred. For specimens not meeting the homogeneity criteria o
27、f 6.2.1 of this standard, or with a possibility of convection within internal cavities, the metering section of a heat flow meter might not cover a representative portion of the specimen: for such specimens the use of a guarded or calibrated hot box apparatus of suitable size should be considered (s
28、ee EN ISO 8990). 1 Scope This standard establishes the principles and criteria to be complied with for the determination of the laboratory steady-state heat transfer properties of masonry walls in a hot box by means of a heat flow meter mounted on one face of the masonry wall to be tested (i.e. the
29、test specimen). It describes the apparatus, measurement technique and necessary data reporting. It does not, however, specify a particular apparatus design since requirements vary particularly in terms of size, and also to a lesser extent, in terms of operating conditions. The property that is measu
30、red is the surface-to-surface thermal resistance of the specimen, provided that the metering section of the heat flow meter covers a representative portion of the specimen, and the homogeneity criteria of 6.2.1 are met. From these measurements the thermal resistance for application in buildings is d
31、erived. The thermal transmittance of a masonry wall can then be calculated from this value with standardized surface coefficients. This standard is applicable to measurements on both dry and moist specimens, provided that the conditions indicated in 5.3.3 are met. The influence of moisture content o
32、n the thermal properties of masonry can be taken into account by measurements at different moisture contents of the specimen in the range of the practical moisture content including the dry state, which corresponds to the most frequent testing condition. The method is also suitable for horizontal el
33、ements such as ceilings and floors. 2 Normative references This standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequ
34、ent amendments to or revisions of any of these publications apply to this standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred applies. EN ISO 6946, Building components and building elements Thermal resistance and therm
35、al transmittance Calculation method (ISO 6946:1996). EN ISO 7345, Thermal insulation Physical quantities and definitions (ISO 7345:1987). EN ISO 8990:1996, Thermal insulation Determination of steady-state thermal transmission properties Calibrated and guarded hot box (ISO 8990:1994). ISO 8301:1991,
36、Thermal insulation Determination of steady-state thermal resistance and related properties Heat flow meter apparatus. ISO 8302:1991, Thermal insulation Determination of steady-state thermal resistance and related properties Guarded hot plate apparatus.Page 4 EN 1934:1998 BSI 1998 1) For more informa
37、tion see EN ISO 8990:1996, annex A. 3 Definitions, symbols and units 3.1 Definitions For the purposes of this standard, the definitions in EN ISO 7345 and EN ISO 8990:1996 and the following definitions apply. 3.1.1 mean radiant temperature 1) appropriate weighting of the temperatures of surfaces “se
38、en” by the specimen for the purpose of determining the radiant heat flow rate to or from the surface of the specimen 3.1.2 environmental temperature 1) appropriate weighting of air and radiant temperatures, for the purpose of determining the heat flow rate to the surface of the specimen 3.1.3 modera
39、tely inhomogeneous specimen specimen which, when tested, meets temperature uniformity criteria as stated in 5.3.2 3.2 Symbols and units Symbol Quantity Unit A area perpendicular to the density of heat flow rate m 2 R s surface thermal resistance m 2 K/W R t specimen thermal resistance (surface-to-su
40、rface) m 2 K/W R T total thermal resistance (environment to environment) m 2 K/W T a air temperature K T n environmental temperature K T r mean radiant temperature K T s surface temperature K U thermal transmittance (1/R T ) W/(m 2 K) d specimen thickness m f calibration factor of the heat flow mete
41、r W/(mVm 2 ) g guard width m h surface coefficient of heat transfer (1/R si or 1/R se ) W/(m 2 K) l half-side of the metering section m p metering section perimeter m q density of heat flow rate W/m 2 DT g temperature difference between metering and guard section K Symbol Quantity Unit F 1 heat flow
42、 rate through the metering section of the specimen W F 2 imbalance heat flow rate between guard section and metering section in the specimen W F 2 9 portion of the imbalance heat flow rate F 2 credited to the average temperature imbalanceDT g W F 2 0 portion of the imbalance heat flow rate F 2 credi
43、ted to temperature non-uniformity on guard section and metering section W F 5 heat flow rate at the edge of the specimen W l f thermal conductivity of the heat flow meter W/(mK) l s thermal conductivity of the material of the specimen in contact with the heat flow meter W/(mK) Subscripts For the pur
44、poses of this standard, the following subscripts apply, i internal, usually hot side e external, usually cold side * moist specimen 4 Principle of the method 4.1 Principle of the apparatus The heat flow meter hot box apparatus is intended to reproduce the boundary conditions of a specimen in steady
45、state conditions between two environments, each at uniform temperature. A specimen is then placed between a hot and a cold chamber in which environmental temperatures are imposed. Heat exchanged at the surfaces of the test specimen involves both convective and radiative contributions. The former dep
46、ends upon air temperatures and air velocity, and the latter depends upon the temperatures and the total hemispherical emissivities of the specimen surfaces and of surfaces “seen” by the test specimen surfaces. The effect of the heat transfer by convection and radiation are conventionally combined in
47、 the concept of an “environmental temperature” and a surface heat transfer coefficient. For this method it is important to limit non-uniformities of temperature on the surface of the specimen and it is not necessary to reproduce exactly end use surface coefficients of heat transfer and environmental
48、 temperatures.Page 5 EN 1934:1998 BSI 1998 NOTE Heat flows at a rate F 1 through the metering area A=( 2l ) 2 ; in the metering area the density of heat flow rate, q, is expected to be uniform; F 2 is an imbalance heat flow rate parallel to the specimen; F 5 is the transverse heat flow rate at the e
49、dge of the specimen; g is the guard width. Figure 1 Principle of a heat flow meter hot box apparatus 4.2 Determination of the density of heat flow rate On the hot side of the specimen a heat flow meter is mounted to measure the density of heat flow rate, q, passing through the specimen and crossing a surface, of area A, located at its centre, see Figure 1. Over this surface, called hereafter the metering section, it is necessary that the density of heat flow rate is sufficiently uniform. The metering
