SIST EN ISO 9288:1997
(Main)Thermal insulation - Heat transfer by radiation - Physical quantities and definitions (ISO 9288:1989)
Thermal insulation - Heat transfer by radiation - Physical quantities and definitions (ISO 9288:1989)
Contains general terms, terms related to surfaces either receiving, transferring or emitting a thermal radiation, terms related to surfaces emitting a thermal radiation, terms related to opaque or semi-transparent surfaces receiving a thermal radiation, terms related to a semi-transparent medium receiving a thermal radiation, and their definition.
Wärmeschutz - Wärmeübertragung durch Strahlung - Physikalische Größen und Definitionen (ISO 9288:1989)
Diese Internationale Norm definiert physikalische Größen und andere Begriffe, die sich auf den Bereich des Wärmeschutzes für Wärmeübertragung durch Strahlung beziehen.
Isolation thermique - Transfert de chaleur par rayonnement - Grandeurs physiques et définitions (ISO 9288:1989)
La présente Norme internationale définit des grandeurs physiques et d'autres termes du domaine de l'isolation thermique liés au transfert de chaleur par rayonnement.
Toplotna izolacija - Prenos toplote s sevanjem - Fizikalne količine in definicije (ISO 9288:1989)
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wärmeschutz - Wärmeübertragung durch Strahlung - Physikalische Größen und Definitionen (ISO 9288:1989)Isolation thermique - Transfert de chaleur par rayonnement - Grandeurs physiques et définitions (ISO 9288:1989)Thermal insulation - Heat transfer by radiation - Physical quantities and definitions (ISO 9288:1989)91.120.10Toplotna izolacija stavbThermal insulation01.060Quantities and units01.040.91Gradbeni materiali in gradnja (Slovarji)Construction materials and building (Vocabularies)ICS:Ta slovenski standard je istoveten z:EN ISO 9288:1996SIST EN ISO 9288:1997en01-december-1997SIST EN ISO 9288:1997SLOVENSKI
STANDARD
SIST EN ISO 9288:1997
SIST EN ISO 9288:1997
SIST EN ISO 9288:1997
INTERNATIONAL STANDARD ’ -IS0 9288 First edition 1989-12-01 Thermal insulation - Heat transfer by radiation - Physical quantities and definitions lsola tion thermique - Transfert physiques et de’finitions de chaleur par ra yonnement - Grandeurs Reference number IS0 9288 : 1989 (E) SIST EN ISO 9288:1997
Is0 9288 : 1989 (El Contents Page Foreword . Introduction . 1 Scope . 2 Normative reference . 3 Generalterms . 4 Terms related to surfaces either receiving, transferring or emitting a thermal radiation . 5 Terms related to surfaces emitting a thermal radiation. . 6 Terms related to opaque or semi-transparent surfaces receiving a thermal radiation . 7 Terms related to a semi-transparent medium receiving a thermal radiation - Combined conduction and radiation heat transfer . Annex A Bibliography . Alohabeticalindex . 0 IS0 1989 . . . III iv 1 1 1 2 4 6 9 16 17 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case postale 56 l CH-1211 Geneve 20 l Switzerland Printed in Switzerland ii SIST EN ISO 9288:1997
IS0 9288 : 1989 (El Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 9288 was prepared by Technical Committee ISO/TC 163, Thermal insulation. Annex A of this International Standard is for information only. . . . Ill SIST EN ISO 9288:1997
IS0 9288 : 1989 (El Introduction This International insulation. Standard forms part of a series of voca bu I aries related to thermal The series will include IS0 7345 : 1987, Thermal insulation - Physical quantities and definitions. IS0 9229 : - 1 1, Thermal insulation - Thermal insulating materials and products - Vocabulary. IS0 9251 : 1987, Thermal insulation - Heat transfer conditions and properties of materials - Vocabulary. IS0 9346 : 1987, Thermal insulation - Mass transfer - Physical quantities and defini- tions. I) To be published. SIST EN ISO 9288:1997
INTERNATIONAL STANDARD IS0 9288 : 1989 (E) Thermal insulation - Heat transfer by radiation - Physical quantities and definitions 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 International 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 encour- aged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. I SO 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 volume. 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 be- tween 0,l pm and 100 pm (see figure 1). 3.2 heat transfer by radiation: Energy exchanges between bodies (apart from 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 ex- changes it is necessary to know how opaque and semi- transparent bodies emit, absorb and transmit radiation as a function of their nature, relative position and temperature. Thermal radiation -0,1~m-100~m w Solar radiation ~O,lpm-3~m h IO4 IO3 102 IO' 100 IO-' IO-2 IO-3 , Waveiength (pm) v Ibl' lb'2 $0'3 11o14 iO'5 IiP 110'7 Frequency (s - ’ ) Infrared Ultraviolet -0,7pm-IOOO~m -0,4pm-IO-* pm Visible -0,4 pm-O,7 brn Figure 1 - Electromagnetic wave spectrum SIST EN ISO 9288:1997
IS0 9288 : 1989 (E) 3.3 Classification of the physical terms associated with thermal radiation Physical terms associated with thermal radiation are classified according to two criteria: - 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 spec- tral interval centred on the wavelength A; 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 propaga- tion defined by a solid angle around the defined direction. 3.4 Classification of materials in relation with radiative transfer OPa que m edium : Medium which tion of the incident radiation. does not transmit any frac- The absorption , emission, reflection dled as surface phenomena. of radiation can be han- semi-transparent medium : Medium in which the incident radiation is progressively attenuated inside the material by ab- sorption or scattering, or both. The absorption, scatteri (volume) phenomena. ng and emission of radiation are bulk 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 temperature of the medium. NOTE - Thermal insulating materials are generally semi-transparent 4 Terms related to surfaces either receiving, transferring or emitting 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. NOTE - This is a total hemispherical quantity. 4.2 total intensity: Radiant heat flow rate divided by the solid angle around the direction d’ : iI@ r$-J = - a52 4.3 total radiance: Radiant heat flow rate divided by the solid angle around the direction 0’ and the projected area normal to this direction : LQ = a% a52 a(Acose) 4.4 spectral radiant heat flow rate: Radiant heat flow rate divided by the spectral interval centred on the wavelength A : a@ qr* = - a;l 4.5 spectral intensity: Total intensity divided by the spectral interval centred on the wavelength 2: %2 r.1 = - a Symbol for quantity @ h-2 k2 @A Iszn Symbol for SI unit (including multiple or sub-multiple) w Wlsr W/(m2sr) W/m W/pm W/(srmm) W/(sr+lm) 2 SIST EN ISO 9288:1997
1s0 9288 : 1989 (El radiance : Total 4.6 spectral wavelength A : radiance divided centred on the NOTES 1 Each spectral term AA is related to the corresponding total term A by a relation of the type 00 3A A2 = zorA = s AA dil Each directional term AQ is related to the corresponding hemispherical term A by a relation of the type aA AS2 = GorA = s ASZ da co a*A ADA = aPanorA = s s AQA dil dQ Q=4x 0 2 Total radiance and spectral radiance are oriented quantities (vectors) defined in each point of space where radiation exists (see figure 3), moreover their values are independent of the particular surface used to define them. Sources which radiate with constant La (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) are not oriented quantities and belong to a surface. 47 . spectral radiant density of heat flow rate vector: Z,A = s + LszZp dSZ 4.8 total radiant density of heat flow rate vector: co s + LQAA dS2 dil density of heat flow rate (in the d irection = ;gJ = s -k-d qr,hl LSZAAmn dQ Symbol for quantity %,An Symbol for Si unit (including multiple or sub-multiple) W/(m34 W/(m*-sr+m) W/(m*~pm) W/m3 W/m* W/m3 W/(m*qm) 3 SIST EN ISO 9288:1997
IS0 9288 : 1989 (E) Symbol for quantity 4+ r,An Symbol for SI unit (including multiple or sub-multiple) W/m3 W/(m*=pm) 4.10 forward component of the spectral radiant density of heat flow rate: = imir,A = s j-b q+ r,An LQIA-n dS2 52=2n; 4.11 backward component of the spectral radiant density of heat flow rate: W/(m*+m) 4-- r,An = ;gJ = - s ++ 4- r,h LQAA-n dS2 sz=*n NOTES 1 We can express Qr,An by the following expression : direction n’ , we have isfer al0 1987, 2. ,3; flow meter method. 5 Terms related to surfaces emitting a thermal radiation 51 solids emissio n: Process in which heat (from molecular #, etc.) is transformed into electromagnetic waves. agitation in gases or atomic agitation 5.2 total excitance : Radiant emitting surface : heat flow rate emitted bY a divided by the area of the W/m* M M = - = q,? or qrD aA NOTE - A4 is the areal hemispherical quantity. of the heat flow rate in each point of an surface. It is a total 5.3 spectral wavelength A : excitance : Total excitance divided spectral interval, W/m3 W/(m*qm) aM M.A = - = Q$ or qrTA an SIST EN ISO 9288:1997
Iso 9288 : 1989 (El 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 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. NOTE - Terms related to black body bear a superscript notation lo). 5.5 black body total excitance: It is expressed by the Stefan-Boltzmann law: MO = UT4 where 0 is equal to 5,67 x IO-* W/(m2mK4); T is the absolute temperature of the black body. 5.6 black body spectral excitance: It is expressed by Planck’s law which relates Mi to the wavelength A and to the absolute temperature of the black body: My = C,A -5 exp(C2M n T) - 1 where Cl = 2dzco* = 3,741 x 1016 W/m*; c* = hcolk = 0,014 388 mmK. h and k are, respectively, the Planck constant and the Boltzmann constant, co is the speed of electromagnetic waves in vacuum. A curveMy = f(A) with a maximum at A, can be drawn for each temperature. ;2, is a function of temperature, but the product Am’ T is constant (Wien’s “displacement law”) : iZ,mT = 2,898x 10B3 mmK MO and My are hemispherical terms. The emission of a black body is isotropic or diffuse, i.e. Lo and LT are independent of the direc- tion (Lambert’s law). The total and the spectral radiance of the black body are expressed by 5.7 emission of real bodies: The evaluation of the emission properties of real materials is made relative to the black body placed in the same conditions of temperature. In general, these properties depend on the nature and surface aspect of the body and vary with wavelength, direc- tion of emission and surface temperature. Symbol for quantity MO Symbol for SI unit (including multiple or sub-multiple) W/m* W/m3 W/(m*mpm) SIST EN ISO 9288:1997
IS0 9288 : 1989 (El 5.8 total directional emissivity : Total radiance, Lsz, emitted by the considered surface, divided by total radiance emitted by the black body, L& at the same temperature: La &a = - LE 5.9 spectral directional emissivity: Spectral radiance, L,,, of the considered surface divi- ded by the spectral radiance emitted by the black body, L&, at the same temperature: Li2A &fJA = - L& 5.10 total hemispherical emissivity: Total hemispherical excitance, M, of the considered surface divided by the total hemispherical excitance of the black body, MO, at the same temperature : M & =p 5.11 spectral hemispherical emissivity: Spectral excitance, MA, of the considered surface divided by the spectral excitance of the black body, My, at the same temperature: MA &A = - Mi 5.12 grey body: Thermal radiator whose hemispherical or directional spectral emissivity is independent of wavelength : &A = &, &$-jl = EQ 5.13 isotropically emitting body: Thermal radiator whose total or spectral emissivity is independent of the direction : EQ = & Q, = q, 5.14 isotropically emitting grey body: Thermal radiator whose emissivity is independent of both wavelength and direction : &ll = &QA = EQ = & These emissivities may vary with temperature : E(T). NOTE - The hypothesis of grey surfaces and isotropic emission, with an emissivity independent of wavelength and direction is generally accepted in computations. In this case the different emissivities of a surface reduce to a single parameter, e. 6 Terms related to opaque or semi-transparent surfaces receiving a thermal radiation When radiant energy of a wavelength A strikes a material surface along a direction d’ inside the solid angle In - a part eDA of the total incident radiation is reflected; Symbol for quantity Symbol for SI unit (including multiple or sub-multiple) SIST EN ISO 9288:1997
~so 9288 : 1989 E) - a part aQA is absorbed inside the material; and - a part zszlz may be transmitted. The three terms aQA, eszA, zszA follow the relationship aQA + em + =G?;\ = 1 Similar relations can be written for spectral, directiona and total terms imply isotropic and incident radiation. a 1 = z 0 = for the black body for opaque bodies I and total hemispherical terms. a = aA; Q = en; r = ~2 for grey bodies a = aaL; Q = ~!s;zA; r = 7s~~ for isotropic or diffuse grey bodies. For a radiation of given direction and wavelength, we have in all cases a&T) = &Q*(T) expres
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