BS EN ISO 9288-1996 Thermal insulation - Heat transfer by radiation - Physical quantities and definitions《隔热 散热传递 物理量和定义》.pdf

1、BRITISH STANDARD BS EN ISO 9288:1996 Thermal insulation Heat transfer by radiation Physicalquantities and definitions The European Standard EN ISO 9288:1996 has the status of a BritishStandard ICS 01.040.91; 01.060.20; 91.120.10BSENISO9288:1996 This British Standard, having been prepared under the d

2、irectionof the Engineering SectorBoard, was published underthe authority of the Standards Board and comesintoeffect on 15July1996 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference RHE/9 Special announcement BSINews August 1994 ISBN 0 580 23283 2 Commit

3、tees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee RHE/9, Thermal insulating materials, upon which the following bodies were represented: Autoclaved Aerated Concrete Products Association Chartered Institution of Building Services

4、Engineers Combustion Engineering Association Concrete Block Association Cork Industry Federation Cranfield University Department of Health Department of the Environment (Building Research Establishment) Department of Trade and Industry (National Physical Laboratory) Electricity Association Eurisol (

5、UK Mineral Wool Association) European Phenolic Foam Association Gypsum Products Development Association Power Generation Contractors Association (PGCA BEAMA Ltd.) Royal Institute of British Architects Thermal Insulation Manufacturers and Suppliers Association (TIMSA) Thermal Insulations Contractors

6、Association The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Calcium Silicate Brick Association Limited Institute of Refrigeration SGS United Kingdom Ltd. Amendments issued since publication Amd. No. Date CommentsBSENISO9288:1996 BSI 11-19

7、99 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Introduction 3 1 Scope 3 2 Normative references 3 3 General terms 3 4 Terms related to surfaces either receiving, transferring or emitting a thermal radiation 5 5 Terms related to surfaces emitting a thermal

8、 radiation 7 6 Terms related to opaque or semi-transparent surfaces receiving a thermal radiation 9 7 Terms related to a semi-transparent medium receiving a thermal radiation Combined conduction and radiation heat transfer 11 Annex A (informative) Bibliography 18 Alphabetical Index 19 Figure 1 Elect

9、romagnetic wave spectrum 4 Figure 2 Definition of the intensity 16 Figure 3 Definition of the radiance 16 Figure 4 Thermal resistance versus thickness 17 Table 1 Summary of the concepts 15 List of references Inside back coverBSENISO9288:1996 ii BSI 11-1999 National foreword This British Standard has

10、 been prepared by Technical Committee RHE/9, and is the English language version of EN ISO 9288 Thermal insulation Heat transfer by radiation Physical quantities and definitions, published by the European Committee for Standardization (CEN). It is identical with ISO9288:1989 published by the Interna

11、tional Organization for Standardization (ISO). EN ISO 9288 was produced as a result of international discussion in which the UK took an active part. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct

12、 application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO 7345:1987 BS EN ISO 7345:1996 Thermal insulation. Physical quantities and definitions (Identical) ISO 9251:1987 BS EN

13、 ISO 9251:1996 Thermal insulations. Heat transfer. Conditions and properties of materials. Vocabulary (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN ISOtitle page, pages2to20, an inside back cover and a back cover. This standard has bee

14、n updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 9288 May 1996 ICS 01.040.91; 01.060.20; 91.120.10 Descriptors: Thermal insulation, radiation, heat

15、 transfer, quantities, units of measurement, symbols, definitions Englishversion Thermal insulation Heat transfer by radiation Physical quantities and definitions (ISO 9288:1989) Isolation thermique Transfert de chaleur par rayonnement Grandeurs physiques et dfinitions (ISO 9288:1989) Wrmeschutz Wrm

16、ebertragung durch Strahlung Physikalische Gren und Definitionen (ISO 9288:1989) This European Standard was approved by CEN on 1995-01-05. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a nationa

17、l standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any o

18、ther 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 official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland

19、, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1996 Copyright reserved to CEN

20、 members Ref. No. EN ISO 9288:1996 EENISO9288:1996 BSI 11-1999 2 Foreword The text of the International Standard from Technical Committee ISO/TC 163, Thermal insulation, of the International Organization for Standardization (ISO) has been taken over as a European Standard by Technical Committee CEN/

21、TC 89, Thermal performance of buildings and building components, the secretariat of which is held by SIS. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 1996, and conflicting national st

22、andards shall be withdrawn at the latest by November 1996. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland,

23、Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.ENISO9288:1996 BSI 11-1999 3 Introduction This International Standard forms part of a series of vocabularies related to thermal insulation. The series will include ISO 7345:1987, Thermal insulation Physic

24、al quantities and definitions. ISO 9229, Thermal insulation Thermal insulating materials and products Vocabulary 1) . ISO 9251:1987, Thermal insulation Heat transfer conditions and properties of materials Vocabulary. ISO 9346:1987, Thermal insulation Mass transfer Physical quantities and definitions

25、. 1 Scope This International Standard defines physical quantities and other terms in the field of thermal insulation relating to heat transfer by radiation. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this Internati

26、onal Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members

27、 of IEC and ISO maintain registers of currently valid International Standards. ISO 7345:1987, Thermal insulation Physical quantities and definitions. 3 General terms 3.1 thermal radiation electromagnetic radiation emitted at the surface of an opaque body or inside an element of a semi-transparent vo

28、lume the thermal radiation is governed by the temperature of the emitting body and its radiative characteristics. It is interesting from a thermal viewpoint when the wavelength range falls between0,1 4m and 100 4m (see Figure 1) 3.2 heat transfer by radiation energy exchanges between bodies (apart f

29、rom one another) by means of electromagnetic waves these exchanges can occur when the bodies are separated from one another by vacuum or by a transparent or a semi-transparent medium. To evaluate these radiation heat exchanges it is necessary to know how opaque and semi-transparent bodies emit, abso

30、rb and transmit radiation as a function of their nature, relative position and temperature 1) To be published.ENISO9288:1996 4 BSI 11-1999 3.3 classification of the physical terms associated with thermal radiation physical terms associated with thermal radiation are classified according to two crite

31、ria: spectral distribution spatial distribution (directional) of the radiation. these physical terms are: total, if they are related to the entire spectrum of thermal radiation (this designation can be considered as implicit); spectral or monochromatic, if they are related to a spectral interval cen

32、tred on the wavelength ; hemispherical, if they are related to all directions along which a surface element can emit or receive radiation; directional, if they are related to the directions of propagation defined by a solid angle around the defined direction. 3.4 classification of materials in relat

33、ion with radiative transfer opaque medium: Medium which does not transmit any fraction of the incident radiation the absorption, emission, reflection of radiation can be handled as surface phenomena semi-transparent medium: Medium in which the incident radiation is progressively attenuated inside th

34、e material by absorption or scattering, or both the absorption, scattering and emission of radiation are bulk (volume) phenomena the radiative properties of an opaque or semi-transparent medium are generally a function of the spectral and directional distribution of incident radiation and of the tem

35、perature of the medium NOTEThermal insulating materials are generally semi-transparent media. Figure 1 Electromagnetic wave spectrumENISO9288:1996 BSI 11-1999 5 Symbol for quantity Symbol for SIunit (including multiple or sub-multiple) 4 Terms related to surfaces either receiving, transferring or em

36、itting a thermal radiation 4.1 radiant heat flow rate; radiant flux: Heat flow rate emitted, transferred or received by a system in form of electromagnetic waves. W NOTEThis is a total hemispherical quantity. 4.2 total intensity: Radiant heat flow rate divided by the solid angle around the direction

37、 : I W/sr 4.3 total radiance: Radiant heat flow rate divided by the solid angle around the directionand the projected area normal to this direction: L W/(m 2 sr) 4.4 spectral radiant heat flow rate: Radiant heat flow rate divided by the spectral interval centred on the wavelength : W/m W/4m 4.5 spec

38、tral intensity: Total intensity divided by the spectral interval centred on the wavelength : I W/(srm) W/(sr4m) 4.6 spectral radiance: Total radiance divided by the spectral interval centred on the wavelength : L W/(m 3 sr) W/(m 2 sr4m) NOTE 1Each spectral term A is related to the corresponding tota

39、l term A by a relation of the type Each directional term A is related to the corresponding hemispherical term A by a relation of the type and ENISO9288:1996 6 BSI 11-1999 NOTE 2Total radiance and spectral radiance are oriented quantities (vectors) defined in each point of space where radiation exist

40、s (see Figure 3), moreover their values are independent of the particular surface used to define them. Sources which radiate with constant L (see 4.3) are called isotropic or diffuse. Intensities are again oriented quantities but belong to a surface (see Figure 2). Radiant flows (total or spectral)

41、are not oriented quantities and belong to a surface. 4.7 spectral radiant density of heat flow rate vector: W/(m 2 4m) 4.8 total radiant density of heat flow rate vector: W/m 3 W/m 2 4.9 spectral radiant density of heat flow rate (in the direction ): W/m 3 W/(m 2 4m) 4.10 forward component of the sp

42、ectral radiant density of heat flow rate: W/m 3 W/(m 2 4m) when 4.11 backward component of the spectral radiant density of heat flow rate: W/(m 2 4m) NOTE 1We can express q r,nby the following expression: NOTE 2In combined unidirectional conduction and radiation heat transfer along a direction , we

43、have where is the density of heat flow rate as defined in ISO 7345:1987, 2.3; is the density of heat flow rate by conduction; is the total radiant density of heat flow rate vector; can be determined experimentally with the guarded hot plate or heat flow meter method. Symbol for quantity Symbol for S

44、Iunit (including multiple or sub-multiple) q r , q r n q r,n q + r,n n 0 q r,n n q n q cd,n q r,n q nENISO9288:1996 BSI 11-1999 7 5 Terms related to surfaces emitting a thermal radiation 5.1 emission: Process in which heat (from molecular agitation in gases or atomic agitation in solids, etc.) is tr

45、ansformed into electromagnetic waves. 5.2 total excitance: Radiant heat flow rate emitted by a surface divided by the area of the emitting surface: M W/m 2 NOTEM is the areal density of the heat flow rate in each point of an emitting surface. It is a total hemispherical quantity. 5.3 spectral excita

46、nce: Total excitance divided by the spectral interval, centred on the wavelength : M W/m 3 W/(m 2 4m) 5.4 black body, (full radiator or Planck radiator): The black body is one that absorbs all the incident radiation for all wavelengths, directions and polarizations. At a given temperature, for each

47、wavelength it emits the maximum thermal energy (maximum spectral excitance). For this reason and because rigorous laws define its emission, the emission of real bodies is compared with that of the black body. NOTETerms related to black body bear a superscript notation ( ). 5.5 black body total excit

48、ance: It is expressed by the Stefan-Boltzmann law: M W/m 2 M = T 4 where is equal to 5,67 10 8W/(m 2 K 4 ); T is the absolute temperature of the black body. 5.6 black body spectral excitance: It is expressed by Plancks law which relatesto the wavelength and to the absolute temperature of the black b

49、ody: W/m 3 W/(m 2 4m) where C 1= 2;hc 0 2= 3,741 10 16W/m 2 ; C 2= hc 0 /k = 0,014 388 mK. h and k are, respectively, the Planck constant and the Boltzmann constant, c ois the speed of electromagnetic waves in vacuum. A curve= f() with a maximum at mcan be drawn for each temperature. mis a function of temperature, but the product m T is constant (Wiens “displacement law”): m T = 2,898 10 3mK M andare hemispherical terms. Sym