1、BRITISH STANDARDBS EN 14705:2005Heat exchangers Method of measurement and evaluation of thermal performances of wet cooling towersThe European Standard EN 14705:2005 has the status of a British StandardICS 27.060.30; 27.200g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48
2、g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 14705:2005This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 July 2005 BSI 28 July 2005ISBN 0 580 46406 7National
3、 forewordThis British Standard is the official English language version of EN 1274:2005.The UK participation in its preparation was entrusted to Technical Committee RHE/30, Heat exchangers, which has the responsibility to: aid enquirers to understand the text; present to the responsible internationa
4、l/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 committee can be obtained on request to its secreta
5、ry.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogueunder the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue o
6、r 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.Summary of pagesThis document comprise
7、s a front cover, an inside front cover, the EN title page, pages 2 to 62, an inside back cover and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUR
8、OPISCHE NORMEN 14705June 2005ICS 27.060.30; 27.200English versionHeat exchangers - Method of measurement and evaluation ofthermal performances of wet cooling towersEchangeurs de chaleur - Mthode de mesure et valuationdes performances thermiques des arorfrigrantshumidesWrmeaustauscher - Verfahren zur
9、 Messung undBewertung der wrmetechnischen Leistungskenndaten vonNasskhltrmenThis European Standard was approved by CEN on 24 March 2005.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national s
10、tandard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards 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 other
11、language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
12、Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagemen
13、t Centre: rue de Stassart, 36 B-1050 Brussels 2005 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14705:2005: EEN 14705:2005 (E) 2Contents pageForeword 31 Scope .42 Normative references .43 Terms, definitions and symbols 53.1 Terms
14、and definitions.53.2 Symbols.74 Performance tests General115 Guarantee 125.1 General 125.2 Guarantee documents 125.3 Validity conditions for measurements 136 Test procedure 156.1 Test parameters 156.2 Quantities to be measured .156.3 Quantities to be determined.176.4 Measurements and calculation of
15、the mean quantities .176.5 Arrangement of measuring devices 246.6 Measuring apparatus 297 Conducting the performance tests307.1 Definition of a test.307.2 Duration of the test .318 Calculation methods.348.1 General 348.2 Methods .349 Evaluation of thermal performances .389.1 General 389.2 Basic ther
16、mal performance test evaluation 389.3 Extended thermal performance test evaluation3910 Test tolerance4710.1 General 4710.2 Error created by non-measurable systematic deviations of operating parameters.47Annex A (informative) Performance curves50Annex B (normative) Requirements concerning the measuri
17、ng apparatus used for the tests 54Annex C (normative) Calculation of the evaporated water flow rate 56Annex D (normative) Reminders on error calculations .59Annex E (normative) Cold water temperature correction for heat added by pump.61Bibliography.62EN 14705:2005 (E) 3Foreword This European Standar
18、d (EN 14705:2005) has been prepared by Technical Committee CEN/TC 110 “Heat exchangers”, the secretariat of which is held by BSI. 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 2005, and
19、 conflicting national standards shall be withdrawn at the latest by December 2005. This document includes a Bibliography. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium
20、, 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. EN 14705:2005 (E) 41 Scope This European Sta
21、ndard specifies requirements, test methods and acceptance tests for thermal performances pumping head verification of wet cooling towers and plume abatement for wet/dry cooling towers. This European Standard is applicable to natural draught wet cooling towers (see in 3.1.2.2) fan assisted natural dr
22、aught cooling tower (see 3.1.2.3), wet/dry cooling towers (see 3.1.2.4) and “Mechanical draught cooling towers“, except series ones. It specifies the test methods, the apparatus required, the limitation of errors and the method for results examination. The acceptance testing covers the verification
23、of the thermal performance data and pumping head of the cooling tower as specified in the contract between the supplier and the purchaser. If these tests are required then this should be recognized at the time of the contract, as additional fittings, and preparations for the test may be required. De
24、viations from the rules laid down below as well as additions need special agreement between purchaser and supplier and should be documented. This standard does not apply to mechanical draught series wet cooling towers which are dealt with in EN 13741. NOTE Terms like “design“, “values“, “guarantee“
25、and “acceptance“ used in this standard should be understood in a technical but not in a legal or commercial sense. 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 refer
26、ences, the latest edition of the referenced document (including any amendments) applies. EN 306, Heat exchangers - Methods of measuring the parameters necessary for establishing the performance EN 872, Water quality - Determination of suspended solids - Method by filtration through glass fibre filte
27、rs EN 60751, Industrial platinum resistance thermometer sensors (IEC 60751:1983 + A1:1986)EN ISO 5167-1, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 1: General principles and requirements (ISO 5167-1:2003) ISO 14
28、38-1, Water flow measurement in open channels using weirs and Venturi flumes - Part 1: Thin-plate weirs ISO 2975-3, Measurement of water flow in closed conduits - Tracer methods - Part 3: Constant rate injection method using radioactive tracers ISO/TR 3313, Measurement of fluid flow in closed condui
29、ts - Guidelines on the effects of flow pulsations on flow-measurement instruments EN 14705:2005 (E) 53 Terms, definitions and symbols 3.1 Terms and definitions For the purposes of this European Standard, the following terms and definitions apply. 3.1.1 cooling tower apparatus in which water is coole
30、d down by heat exchange with ambient air 3.1.2 wet cooling tower cooling tower in which the heat exchange between the water and the air is achieved by a direct contact 3.1.2.1 mechanical draught wet cooling tower wet cooling tower where the air circulation is produced by a fan 3.1.2.1.1 series type
31、mechanical draught wet cooling tower mechanical draught wet cooling tower, the design of which is fixed and described in the manufacturers catalogue and for which the performance data are available, which allows tests evaluation over the defined range of operating conditions 3.1.2.1.2 non series typ
32、e mechanical draught wet cooling tower mechanical draught wet cooling tower, the design of which is project dependent and for which the performance data and test evaluation at specific operating conditions may be subject to agreement 3.1.2.2 natural draught cooling tower wet cooling tower where the
33、air circulation is produced only by a density difference between the cold air outside the cooling tower and the hot air inside 3.1.2.3 fan assisted natural draught cooling tower natural draught cooling tower with the addition of fan to boost the draught 3.1.2.4 wet/dry cooling tower (reduced plume c
34、ooling tower) cooling tower comprising two parts. In the first part, the heat exchange between the water and the air is achieved by direct contact and through a tight wall in the second part 3.1.2.4.1 reduced plume wet/dry cooling tower wet/dry cooling tower designed for plume abatement 3.1.2.4.2 wa
35、ter conservation wet/dry cooling tower wet/dry cooling tower designed for water conservation 3.1.3 air flow total quantity of air, including associated water vapour flowing through the tower 3.1.3.1 counterflow where air and water flows are in opposite direction in the filling EN 14705:2005 (E) 63.1
36、.3.2 cross flow where air flows perpendicular to the water in the filling 3.1.4 ambient wet (dry) bulb temperature wet (dry) bulb temperature of air measured windward of the tower and free from the influence of the tower 3.1.5 approach difference between recooled water temperature and inlet air wet
37、bulb temperature 3.1.6 inlet water flow quantity of hot water flowing into the tower 3.1.7 cold water basin device underlying the tower to receive the recooled water from the tower and direct its flow to the suction line or sump 3.1.8 cooling range difference between the hot water temperature and th
38、e recooled water temperature NOTE The term “range“ is also applied to this definition, but is regarded as a non-preferred term. 3.1.9 drift loss water lost from the tower as liquid droplets with the same chemical characteristics as the circulating water, entrained in the outlet air 3.1.10 heat load
39、rate of heat to be removed from the water within the tower 3.1.11 hot water temperature temperature of inlet water 3.1.12 inlet air wet (dry) bulb temperatures average wet (dry) bulb temperatures of the inlet air; including any recirculation effect 3.1.13 make-up water added to the circulating water
40、 system to compensate for water loss from the system by evaporation, drift, purge and leakage 3.1.14 purge (blow down) water discharged from the system to control concentration of salts or other impurities in the circulating water 3.1.15 recooled water temperature average temperature of the water at
41、 the cold water basin discharge excluding the effect of any make-up entering the basin or at the exhaust of the exchanger for wet/dry cooling tower EN 14705:2005 (E) 73.1.16 recirculation portion of the outlet air that re-enters the tower 3.1.17 interference intake of outlet air of adjacent cooling
42、towers 3.1.18 tower pumping head total head of water required at the inlet to the tower, to deliver the inlet water through the distribution system 3.1.19 surfacic flow inlet water flow expressed in quantity per unit of plan packing area of the tower 3.1.20 wet (dry) bulb temperature the temperature
43、 indicated by an adequately ventilated and wetted (non-wetted) thermometer in the shade and (where applicable) protected from any radiation effect 3.1.21 atmospheric gradient air dry bulb temperature variation with altitude expressed in degree Celsius per 100 m 3.2 Symbols For the purposes of this E
44、uropean Standard, the symbols of Table 1 shall apply. EN 14705:2005 (E) 8Table 1 Symbols Designated parameters Units A Transfer surface per unit of volume m-1a Angle of an elbow degree ap Approach (tc- tw) KC Heat coefficient - CEV Evaporation coefficient related to the difference in water content k
45、gm-2s-1CFLoad loss coefficient - CFV Evaporation coefficient related to the difference in water content kgm-2s-1CSSpecific water consumption kgJ-1cpaMass heat capacity of the air at constant pressure Jkg-1K-1cpeMass heat capacity of the water Jkg-1K-1cpvMass heat capacity of the vapour at constant p
46、ressure Jkg-1K-1D10Direction of the reference wind in relation to the north degree d Hydraulic diameter m FpFan motor power kW FpGGuaranteed fan motor power kW g Gravity acceleration ms-2H Draught height m h Mass enthalpy of the air Jkg-1h1 Mass enthalpy of the air at the air inlet calculated from p
47、a, ts and Jkg-1h2Mass enthalpy of the saturated hot air at the air outlet downstreamfrom the drift eliminators Jkg-1hsMass enthalpy of the saturated moist air at the water temperature Jkg-1hs1, hs2Mass enthalpy of the saturated moist air at the water temperature with 1 = inlet, 2 = outlet Jkg-1k Num
48、ber of tests meqKAVMerkel number - LvtWater vaporization latent heat at temperature t Jkg-1m Circulating water volume flow rate at the cooling tower inlet m3s-1mbCalculated blow-down water volume flow rate m3s-1mbmMeasured blow-down water volume flow rate m3s-1(to be continued) EN 14705:2005 (E) 9Ta
49、ble 1 (continued)Symbols Designated parameters Units mEEvaporated water volume flow rate m3s-1mmMake-up water volume flow rate m3s-1m0Number of a wind velocity class mpVolume flow rate of water entrained by drift losses m3s-1N Characteristic index of nominal pattern n Constant exponent of the exchange law nbNumber of tests per m0class nbm Number of recorded values for each test P Thermal load kW paAtmospheric pressure Pa pvsSaturating vapour pressure Pa psStatic pressure Pa pvPartial pressure of vapour in the air Pa qmasDry air mass flow r
