BS-EN-62194-2005.pdf

BRITISH STANDARD BS EN 62194:2005 Method of evaluating the thermal performance of enclosures The European Standard EN 62194:2005 has the status of a British Standard ICS 31.240 ? Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 62194:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 6 January 2006 © BSI 6 January 2006 ISBN 0 580 47195 0 National foreword This British Standard is the official English language version of EN 62194:2005. It is identical with IEC 62194:2005. The UK participation in its preparation was entrusted to Technical Committee EPL/48, Electromechanical components and mechanical structures for electronic equipment, which has the responsibility to: A list of organizations represented on this committee can be 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 Catalogue under 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 application. Compliance with a British Standard 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; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 31 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD EN 62194 NORME EUROPÉENNE EUROPÄISCHE NORM October 2005 CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels © 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 62194:2005 E ICS 31.240 English version Method of evaluating the thermal performance of enclosures (IEC 62194:2005) Méthode d'évaluation de la performance thermique des enveloppes (CEI 62194:2005) Verfahren zur Bewertung der Wärmeleistung von Gehäusen (IEC 62194:2005) This European Standard was approved by CENELEC on 2005-09-01. CENELEC members are 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 the Central Secretariat or to any CENELEC 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 CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Foreword The text of document 48D/324/FDIS, future edition 1 of IEC 62194, prepared by SC 48D, Mechanical structures for electronic equipment, of IEC TC 48, Electromechanical components and mechanical structures for electronic equipment, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62194 on 2005-09-01. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2006-06-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2008-09-01 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 62194:2005 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated: IEC 60297-2 NOTE Harmonized as HD 493.2 S1:1988 (not modified). IEC 60721 NOTE Harmonized in EN 60721 series (not modified). IEC 60917-2 NOTE Harmonized as EN 60917-2:1994 (not modified). IEC 61587-1 NOTE Harmonized as EN 61587-1:1999 (not modified). IEC 61969-1 NOTE Harmonized as EN 61969-1:2000 (not modified). IEC 61969-2 NOTE Harmonized as EN 61969-2:2000 (not modified). IEC 61969-3 NOTE Harmonized as EN 61969-3:2001 (not modified). _ EN 62194:2005 2 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CONTENTS INTRODUCTION.5 1 Scope 6 2 Normative references .6 3 Terms, definitions, symbols and abbreviations.7 3.1 Definition of enclosure design principles 7 3.2 Symbols and abbreviated terms .7 4 Flow chart for establishing the absorption factor 9 5 Evaluation of the heat load . 10 6 Environmental conditions 10 6.1 Outdoor applications10 6.2 Indoor applications 1 1 7 Determination of the enclosure absorption factor .11 7.1 Measurement set-up 11 7.2 Calculation . .13 8 Result and presentation . .13 8.1 Comparison of different enclosure designs .13 8.2 Heat transfer through walls 14 8.3 Airflow between walls 15 8.4 Results for single-wall enclosures 16 8.5 Results for double-wall enclosures (simple method) .17 Annex A (normative) Heat transfer rate 2 0 Annex B (informative) Geometric relations for solar radiation 20 Annex C (informative) Example for single and double wall calculation .22 Annex D (informative) Iteration method for exact results of a double wall enclosure 24 Annex ZA (normative) Normative references to international publications with their corresponding European publications.3 1 Bibliography .30 Figure 1 Enclosure types. .7 Figure 2 Flow chart for establishing the absorption factor9 Figure 3 Example of measurement set-up for enclosure absorption factor .12 Figure 4 Heat transfer through walls .14 Figure 5 Airflow between walls .16 Figure B.1 Geometric angles for solar radiation impact .20 Figure D.1 Thermal model for double wall enclosure .24 Figure D.2 Iteration procedure for double-wall enclosures .26 EN 62194:2005 3 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Table 1 Convection heat transfer coefficients .11 Table 2 Parameters for single-wall enclosure calculation 17 Table 3 Parameters for double-wall enclosure calculation (simple method)18 Table C.1 Given parameters for single-wall enclosure calculation .22 Table C.2 Given parameters for double-wall enclosure calculation (simple method) 23 Table D.1 Given parameters for double wall enclosure calculation 28 Table D.2 Starting values for iterations .28 Table D.3 Results after first iteration block . 28 Table D.4 Results after second iteration block 29 EN 62194:2005 4 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTRODUCTION When installing enclosures with electronic components, the climatic conditions are very important, as the function of the electronics is affected by the ambient temperature. Because of heat load and solar radiation, the enclosures become hot. Since the heat transfer via the enclosure surface is often not sufficient, a climate control unit may be required to maintain tolerable enclosure internal conditions. For the enclosure design, the effect of the solar radiation was either estimated via the solar constant or added with a fixed value for heat load. Closer observation of the radiation allows for a more accurate and cost-efficient method of enclosure thermal performance evaluation. There are existing standards defining the environmental conditions: for outdoor enclosures, IEC 61969-3 and EN 300 019 and, for indoor enclosures, IEC 60721, EN 300 019, and IEC 61587-1. Dimensional standards referred to for outdoor enclosures are IEC 61969-1 and IEC 61969-2, and, for indoor enclosures, IEC 60297-2, EN 300 119 and IEC 60917-2. As requested by users and manufacturers, a unified heat management property of empty enclosures had to be developed. This standard establishes a method of thermal performance evaluation for enclosures. EN 62194:2005 5 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI METHOD OF EVALUATING THE THERMAL PERFORMANCE OF ENCLOSURES 1 Scope This International Standard provides a method of thermal performance evaluation for empty indoor enclosures according to IEC 60917 and IEC 60297, and, for outdoor enclosures according to IEC 61969. This standard contains criteria to determine the thermal absorption factors relating to principles of enclosure design; internal heat load; sun radiation. The enclosure absorption factor is intended to provide a common value for comparing and selecting enclosures built in accordance with this standard. 2 Normative references The following referenced documents 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. IEC 60297 (all parts), Dimensions of mechanical structures of the 482,6 mm (19 in) series IEC 60721-2-4, Classification of environmental conditions Part 2-4: Environmental condi- tions appearing in nature Solar radiation and temperature IEC 60917 (all parts), Modular order for the development of mechanical structures for electronic equipment practices IEC 61969 (all parts), Mechanical structures for electronic equipment Outdoor enclosures EN 62194:2005 6 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 3 Terms, definitions, symbols and abbreviations 3.1 Definition of enclosure design principles The enclosure design influences heat flow. The following enclosure types are defined and illustrated in Figure 1. A Single-wall B Double-wall (with insulation/without insulation/with or without airflow) C Single-wall and sun-shield D Double-wall and sun-shield (with insulation/without insulation/with or without airflow) A B C, D IEC 1258/05 Figure 1 Enclosure types 3.2 Symbols and abbreviated terms A Area of the surfaces of the enclosure excluding the bottom in square metres (m2) A Material absorption factor E A Enclosure absorption factor AW Cross-section of the double wall in square metres (m2) aw Wall azimuth angle a0 Sun azimuth angle cF Corrective factor for double-wall calculation (simple method) cp,air Specific heat capacity of air in joules per kilogram and per kelvin (J/(kg K) h Sun-height angle k Heat transfer rate in watts per square meter and per kelvin (W/(m2 K) P Heat load in watts (W) EN 62194:2005 7 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 8 10 Tr Q ? Heat transfer through enclosure walls caused by transmission in watts (W) vent Q ? Heat transfer transported by the airflow between the double wall in watts (W) dif q? Diffuse solar radiation in watts per square metre (W/m2) g q? Solar radiation received on horizontal surfaces in watts per square metre (global radiation) (W/m2) i q? Specific internal heat load in watts per square metre (W/m2) s q? Solar total radiation received through the atmosphere in watts per square metre (W/m2) (normal direction to the sun) w q? Solar radiation (direct and diffuse) on the enclosure wall in watts per square metre (W/m2) sj Material thickness of material j used for the wall in metres (m) TA Ambient air temperature in kelvins (K) TW Wall temperature on the outside of the enclosure in kelvins (K) ta Ambient temperature in degrees Celsius (°C) ta,max Maximum ambient temperature in degrees Celsius (°C) ti Average temperature inside the enclosure in degrees Celsius (°C) ti,max Maximum allowed temperature inside the enclosure in degrees Celsius (°C) tm Air temperature between the double wall in degrees Celsius (°C) tw Wall temperature on the outside of the enclosure in degrees Celsius (°C) twi Wall temperature of the interior wall of a double-wall enclosure in degrees Celsius (°C) w Wind speed in metres per second (m/s) ww Air speed between the double wall in metres per second (m/s) ka Convection heat transfer coefficient outside in watts per square metre and per kelvin (W/(m2 K) ki Convection heat transfer coefficient inside in watts per square metre and per kelvin (W/(m2 K) rad Radiation heat transfer coefficient in watts per square metre and per kelvin (W/(m2 K) Emissivity of the enclosure surface treatment Incident angle j Thermal conductivity of material j used for the wall in watts per metre and per kelvin (W/(m K) air Density of air in kilograms per cubic metre (kg/m3) EN 62194:2005 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 9 4 Flow chart for establishing the absorption factor The flow chart shown in Figure 2 describes the different steps that are necessary for the determination of the thermal performance of the enclosure. The details of the different steps are explained in the clauses following this chart. Evaluation of the heat load (see Clause 5) Definition of the environmental conditions (see Clause 6) Outdoor application: Maximum ambient temperature Thermal criteria Solar radiation Wind Indoor application: Maximum ambient temperature Thermal criteria Enclosure absorption factor known? Result and presentation (see Clause 8) Determination of the enclosure absorption factor (see Clause 7) NO YES IEC 1259/05 Figure 2 Flow chart for establishing the absorption factor EN 62194:2005 Licensed Copy: sheffieldun sheffieldun, na, Sat Nov 11 08:34:12 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 10 5 Evaluation of the heat load For thermal performance it is important to understand the heat load in the interior of the enclosure. If the