1、November 2008DEUTSCHE NORM English price group 21No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 27.220; 91.120.10!$Rg
2、“1476899www.din.deDDIN EN ISO 12241Thermal insulation for building equipment and industrial installations Calculation rules (ISO 12241:2008)English version of DIN EN ISO 12241:2008-11Wrmedmmung an haus- und betriebstechnischen Anlagen Berechnungsregeln (ISO 12241:2008)Englische Fassung DIN EN ISO 12
3、241:2008-11SupersedesDIN EN ISO 12241:1998-06www.beuth.deDocument comprises 53 pagesDIN EN ISO 12241:2008-11 2 National foreword This standard has been prepared by Technical Committee ISO/TC 163 “Thermal performance and energy use in the built environment”, Subcommittee SC 2 “Calculation methods” in
4、 collaboration with Technical Committee CEN/TC 89 “Thermal performance of buildings and building components” (Secretariat: SIS, Sweden). and Civil Engineering Standards Committee), Technical Committee NA 005-56-10 AA Dmmarbeiten an technischen Anlagen. The DIN Standards corresponding to the Internat
5、ional Standards referred to in clause 2 of the EN are as follows: ISO 7345 DIN EN ISO 7345 ISO 9346 DIN EN ISO 9346 ISO 10211 DIN EN ISO 10211 ISO 23993 DIN EN ISO 23993 ISO 13787 DIN EN ISO 13787 To improve the applicability of this standard, the following symbols are presented in addition to those
6、 specified in subclause 3.2: Symbol Definition Unit lequivalent length m 2thermal conductivity of the second layer W/(m K) Amendments This standard differs from DIN EN ISO 12241:1998-06 as follows: a) A method for the determination of correction terms for thermal transmittance and linear thermal tra
7、nsmit-tance of pipes has been included. Previous editions DIN EN ISO 12241: 1998-06 The responsible German body involved in its preparation was the Normenausschuss Bauwesen (Building DIN EN ISO 12241:2008-11 3 National Annex NA (informative) Comparison of symbols according to this standard and VDI 2
8、055 Definition DIN EN ISO 12241 VDI 2055 Heat flow rate .Q Density of heat flow rate q q Linear density of heat flow rate ql qlCelsius temperature Surface coefficient of heat transfer h Enthalpy h h Thermal transmittance U k Thickness d s Time t t Air velocity v w Diameter D d Height H H Thermal res
9、istance R R Linear thermal resistance RlRlin m K/W Perimeter P U Surface resistance of heat transfer Rsl/ DIN EN ISO 12241:2008-11 4 National Annex NB (informative) Bibliography DIN EN ISO 7345, Thermal insulation Physical quantities and definitions DIN EN ISO 9346, Hygrothermal performance of build
10、ings and building materials Physical quantities for mass transfer Vocabulary DIN EN ISO 10211, Thermal bridges in building construction Heat flows and surface temperatures Detailed calculations DIN EN ISO 23993, Thermal insulation products for building equipment and industrial installations Determin
11、ation of design thermal conductivity DIN EN ISO 13787, Thermal insulation products for building equipment and industrial installations Determination of declared thermal conductivity VDI 2055, Thermal insulation for heated and refrigerated industrial and domestic installations Calculations, guarantee
12、s, measuring and testing methods, quality assurance, supply conditions EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 12241 June 2008 ICS 91.140.01; 91.120.10 Supersedes EN ISO 12241:1998English Version Thermal insulation for building equipment and industrial installations - Calculation ru
13、les (ISO 12241:2008) Isolation thermique des quipements de btiments et des installations industrielles - Mthodes de calcul (ISO 12241:2008) Wrmedmmung an haus- und betriebstechnischen Anlagen - Berechnungsregeln (ISO 12241:2008) This European Standard was approved by CEN on 1 May 2008. CEN members a
14、re bound to comply 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
15、 the CEN Management Centre 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 CEN Management Centre has the sa
16、me status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
17、Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means res
18、erved worldwide for CEN national Members. Ref. No. EN ISO 12241:2008: E2 DIN EN ISO 12241:2008-11 EN ISO 12241:2008 (E) Contents Page Foreword3 Introduction .4 1 Scope 5 2 Normative references 5 3 Terms, definitions and symbols.5 3.1 Terms and definitions .5 3.2 Definition of symbols 6 3.3 Subscript
19、s 7 4 Calculation methods for heat transfer.7 4.1 Fundamental equations for heat transfer7 4.2 Surface temperature. 18 4.3 Prevention of surface condensation. 21 4.4 Determination of total heat flow rate for plane walls, pipes and spheres 24 5 Calculation of the temperature change in pipes, vessels
20、and containers 25 5.1 Longitudinal temperature change in a pipe . 25 5.2 Temperature change and cooling times in pipes, vessels and containers 26 6 Calculation of cooling and freezing times of stationary liquids 26 6.1 Calculation of the cooling time for a given thickness of insulation to prevent th
21、e freezing of water in a pipe. 26 6.2 Calculation of the freezing time of water in a pipe 28 7 Determination of the influence of thermal bridges . 29 7.1 General. 29 7.2 Calculation of correction terms for plane surfaces 30 7.3 Calculation of correction terms for pipes 30 8 Underground pipelines 31
22、8.1 General. 31 8.2 Calculation of heat loss (single line) without channels 31 8.3 Other cases . 33 Annex A (normative) Thermal bridges in pipe insulation 34 Annex B (informative) Projecting thermal bridges of roughly constant cross-section 37 Annex C (informative) Examples 42 Bibliography. 49 3 For
23、eword This document (EN ISO 12241:2008) has been prepared by Technical Committee ISO/TC 163 “Thermal performance and energy use in the built environment“ in collaboration with Technical Committee CEN/TC 89 “Thermal performance of buildings and building components” the secretariat of which is held by
24、 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 December 2008, and conflicting national standards shall be withdrawn at the latest by December 2008. Attention is drawn to the possibility tha
25、t some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 12241:1998. According to the CEN/CENELEC Internal Regulations, the national standards organizat
26、ions of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romani
27、a, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 12241:2008 has been approved by CEN as a EN ISO 12241:2008 without any modification. DIN EN ISO 12241:2008-11 EN ISO 12241:2008 (E) Introduction Methods relating to conduction are direct math
28、ematical derivations from Fouriers law of heat conduction, so international consensus is purely a matter of mathematical verification. No significant difference in the equations used in the member countries exists. For convection and radiation, however, there are no methods in practical use that are
29、 mathematically traceable to Newtons law of cooling or the Stefan-Boltzman law of thermal radiation, without some empirical element. For convection in particular, many different equations have been developed, based on laboratory data. Different equations have become popular in different countries, a
30、nd no exact means are available to select between these equations. Within the limitations given, these methods can be applied to most types of industrial, thermal-insulation, heat-transfer problems. These methods do not take into account the permeation of air or the transmittance of thermal radiatio
31、n through transparent media. The equations in these methods require for their solution that some system variables be known, given, assumed or measured. In all cases, the accuracy of the results depends on the accuracy of the input variables. This International Standard contains no guidelines for acc
32、urate measurement of any of the variables. However, it does contain guides that have proven satisfactory for estimating some of the variables for many industrial thermal systems. lt should be noted that the steady-state calculations are dependent on boundary conditions. Often a solution at one set o
33、f boundary conditions is not sufficient to characterize a thermal system that operates in a changing thermal environment (process equipment operating year-round, outdoors, for example). In such cases, it is necessary to use local weather data based on yearly averages or yearly extremes of the weathe
34、r variables (depending on the nature of the particular calculation) for the calculations in this International Standard. In particular, the user should not infer from the methods of this International Standard that either insulation quality or avoidance of dew formation can be reliably assured based
35、 on minimal, simple measurements and application of the basic calculation methods given here. For most industrial heat flow surfaces, there is no isothermal state (no one, homogeneous temperature across the surface), but rather a varying temperature profile. This condition suggests the requirement f
36、or numerous calculations to properly model thermal characteristics of any one surface. Furthermore, the heat flow through a surface at any point is a function of several variables that are not directly related to insulation quality. Among others, these variables include ambient temperature, movement
37、 of the air, roughness and emissivity of the heat flow surface, and the radiation exchange with the surroundings (which often vary widely). For calculation of dew formation, variability of the local humidity is an important factor. Except inside buildings, the average temperature of the radiant back
38、ground seldom corresponds to the air temperature, and measurement of background temperatures, emissivities and exposure areas is beyond the scope of this International Standard. For these reasons, neither the surface temperature nor the temperature difference between the surface and the air can be u
39、sed as a reliable indicator of insulation performance or avoidance of dew formation. Clauses 4 and 5 of this International Standard give the methods used for industrial thermal insulation calculations not covered by more specific standards. In applications where it is not necessary to assure precise
40、 values of heat energy conservation or (insulated) surface temperature, or where critical temperatures for dew formation are either not approached or not a factor, these methods can be used to calculate heat flow rates. Clauses 6 and 7 of this International Standard are adaptations of the general eq
41、uation for specific applications of calculating heat flow temperature drop and freezing times in pipes and other vessels. Annexes B and C of this International Standard are for information only. 4 DIN EN ISO 12241:2008-11 EN ISO 12241:2008 (E) 1 Scope This International Standard gives rules for the
42、calculation of heat-transfer-related properties of building equipment and industrial installations, predominantly under steady-state conditions. This International Standard also gives a simplified approach for the treatment of thermal bridges. 2 Normative references The following referenced document
43、s are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 7345, Thermal insulation Physical quantities and definitions ISO 9346, Hygroth
44、ermal performance of buildings and building materials Physical quantities for mass transfer Vocabulary ISO 10211, Thermal bridges in building construction Heat flows and surface temperatures Detailed calculations ISO 13787, Thermal insulation products for building equipment and industrial installati
45、ons Determination of declared thermal conductivity ISO 23993, Thermal insulation for building equipment and industrial installations Determination of design thermal conductivity 3 Terms, definitions and symbols 3.1 Terms and definitions For the purposes of this document, the terms and definitions gi
46、ven in ISO 7345, ISO 9346, ISO 13787 and ISO 23993 apply. 5 DIN EN ISO 12241:2008-11 EN ISO 12241:2008 (E) 3.2 Definition of symbols Symbol Definition Unit A area m2artemperature factor K3C thickness parameter (see 4.2.2) m Crradiation coefficient W/(m2K4) cpspecific heat capacity at constant pressu
47、re kJ/(kgK) D diameter m, mmd thickness m, mmH height m h surface coefficient of heat transfer W/(m2K) l length m m mass kg m mass flow rate kg/h P perimeter m q density of heat flow rate W/m2qdlinear density of heat flow rate for ducts W/m qllinear density of heat flow rate W/m R thermal resistance
48、 m2K/W Rdlinear thermal resistance of ducts mK/W Rllinear thermal resistance mK/W Rlelinear thermal surface resistance mK/W Rssurface resistance of heat transfer m2K/W Rsphthermal resistance for hollow sphere K/W tfrfreezing time h tvcooling time h twptime until freezing starts h T thermodynamic tem
49、perature K U thermal transmittance W/(m2K) Ullinear thermal transmittance W/(mK) Usphthermal transmittance for hollow sphere W/K UBthermal transmittance of thermal bridge W/(m2K) UBadditional term corresponding to installation-related and/or irregular insulation-related thermal bridges W/(m2K) UTtotal thermal transmittance for plane wall W/(m2K) UT,ltotal linear thermal transmittance W/(mK) UT,sphtotal thermal transmittance for hollow sphere W/K v air velocity m/s 6 DIN EN ISO 12241:2008-11 EN ISO 12241:2
