1、PUBLISHED DOCUMENT PD CR 14378:2002 CR 14378:2002 Incorporating Corrigendum No. 1 Ventilation for buildings Experimental determination of mechanical energy loss coefficients of air handling components ICS 91.140.30 PD CR 14378:2002 This Published Document, having been prepared under the direction of
2、 the Engineering Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 6 May 2002 BSI 15 January 2003 ISBN 0 580 39422 0 National foreword This Published Document reproduces verbatim CR 14378:2002, including Corrigendum July 2002. T
3、he UK participation in its preparation was entrusted to Technical Committee RHE/2, Air distribution and air diffusion, 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 impl
4、ement 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 do
5、es not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK int
6、erests 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 CR title page, pages 2 to 24, an inside back cover and a back cover. The BSI copyright date displayed in this doc
7、ument indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments 14069 Corrigendum No. 1 15 January 2003 Replacement of Figure A.4, Figure A.5, and Figure A.6CENREPORT RAPPORTCEN CENBERICHT CR14378 January2002 ICS Englishversion VentilationforbuildingsExp
8、erimentaldeterminationof mechanicalenergylosscoefficientsofairhandlingcomponents ThisCENReportwasapprovedbyCENon10November2001.IthasbeendrawnupbytheTechnicalCommitteeCEN/TC156. CENmembersarethenationalstandardsbodiesofAustria,Belgium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Iceland,Irela
9、nd,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2002CEN Allrightsofexploitationinanyformandbyanymeansreserved wor
10、ldwideforCENnationalMembers. Ref.No.CR14378:2002E Incorporating corrigendum July 2002CR14378:2002(E) 2 CONTENTS Foreword3 1 Scope 4 2 Normativereferences 4 3 Termsanddefinitions . 4 4 Testmethod. .4 4.1 Principle4 4.2 Testinstallation. .6 4.3 Rectangularandothernoncircularductsandcomponents 7 4.4 Me
11、asurements7 4.5 Calculationmethod .8 4.6 Calculationofuncertainties 9 4.7 Numberoftestpoints. .11 4.8 Presentationofdata 11 AnnexA 12 A.1 Componentswithinletdifferentfromoutlet(divergingorconverging)12 A.2 Componentswithfreeinlets. 12 A.3 Componentswithfreeoutlets 13 A.4 Componentswithtwoinlets(conv
12、ergingjunctions). 14 A.5 Componentswithtwooutlets(divergingjunctions). .17 A.6 Componentswithoutswirl 18 AnnexB .20 B.1 Flowratemeasurement. 20 B.2 Pressuremeasurement .21 B.3 Temperaturemeasurement. 23 B.4 Humiditymeasurement .23 Bibliography24CR14378:2002(E) 3 Foreword ThisTechnicalReporthasbeenpr
13、eparedbyTechnicalCommitteeCEN/TC156,Ventilationforbuildings,the secretariatofwhichisheldbyBSI. Thisreportshouldbeconsideredwithaseriesofstandardsforductworkusedforventilationandair conditioningofbuildingsforhumanoccupancy. ThepositionofthisreportinthefieldofmechanicalbuildingservicesisshowninFigure1
14、. MechanicalBuilding Services Controlsystems Ventilationandair conditioningsystems Heatingsystems Airhandlingunits Ductwork Installation Circularsheet metalducts Dimensions Circularsheetmetal ductsStrengthand leakage Rectangularsheet metalducts Strengthand leakage Hangersand supports Rectangularshee
15、t metalducts Dimensions Measurementof ductsurfacearea Requirementsfor ductwork componentsto facilitate maintenance Flanges Identification Flexibleducts Determinationof mechanical energyloss Ductworkmade ofinsulation ductboards Figure1 PositionofCR14378inthefieldofmechanicalbuildingservicesCR14378:20
16、02(E) 4 1Scope ThisTechnicalReportspecifiesunifiedtestproceduresandconditionsfortheexperimentaldeterminationof mechanicalenergylosscoefficientsforductworkcomponentssuchasducts,bends,diffusors,converging junctionsanddivergingjunctions. 2 Normativereferences ThisTechnicalReportincorporatesbydatedorund
17、atedreference,provisionsfromotherpublications.These normativereferencesarecitedattheappropriateplacesinthetextandthepublicationsarelistedhereafter. Fordatedreferencesthesubsequentamendmentstoorrevisionsofanyofthesepublicationsapplytothis TechnicalReportonlywhenincorporatedinitbyamendmentorrevision.F
18、orundatedreferencesthelatest editionofthepublicationreferredtoapplies(includingamendments). CR12792 Ventilationforbuildings Symbols,unitsandterminology ISO5221 Airflowmeasurementinanairhandlingduct. 3 Termsanddefinitions Forthepurposesofthisreport,thetermsanddefinitionsandsymbolsareprincipallyinacco
19、rdancewithCEN TechnicalReportCR12792. 4 Testmethod 4.1Principle Inprincipleitispossibletogiveadefinitionofenergylossproducedbyacomponentofairdistribution systems. Figure2 Diagrammaticrepresentationofenergyflow Themechanicalenergylossintheflowwithinatypicalcomponent,asrepresentedinFigure2,isequaltoth
20、e differencebetweentheenergyenteringthecomponentthroughsectionIandtheenergyleavingthe componentthroughsection2. ByapplyingthegeneralizedBernoulliformulawhichtakesintoaccountthefactthattheairiscompressible, thereforeitsdensityvariesthroughthecomponent,andthat itisarealfluid,thevelocitydistributionina
21、 sectionbeingnonuniform,theenergylossperunitmass(J/kg)isexpressedby: 12 12CR14378:2002(E) 5 2 1 2 2 12 2 1 1 12 2 1 2 1 2 2 Z Z g v v p p p y m A m A (1) where y istheenergylossperunitmass pistheabsolutepressure V m isthemeanflowvelocity Zisthealtitude 12 isthefluiddensity g isthefreefallacceleratio
22、n A isthekineticenergyfactor Thekineticenergyfactor A canbedeterminedbyPitottubeexplorationinthecrosssectionunder consideration.Thedensity 12 dependsontheflowvariationthroughthecomponent. Inpracticethepresenceofanairhandlingcomponentinaductsystemmodifiestheflowstructureupstream anddownstreamofthecom
23、ponent.Forthisreasonthepracticaldeterminationofthemechanicalenergy lossesisgenerallymadeonthetestinstallationasshowninFigure3. Figure3 Diagrammaticrepresentationofthetestinstallation Astraightductofthelength L 01 isinstalledupstreamofthecomponentandastraightductofthelength L 23 downstream.Themeasure
24、mentsections(0upstreamand3downstream)areconsequentlydistant fromthecomponent.Fromthetestvaluesobtainedinthesesectionsthecharacteristicsoffloware calculatedforthesectionsIand2andthenusedinthegeneralizedBernoulliformulatoobtainthe mechanicalenergyloss. Thechoiceoflengths L 01 andL 23 andtheassumptions
25、concerningtheflowthroughtheseductsectionscan causedifferencesinthefinalresults.Thereforeanagreementonthechoiceoflengthsshallbeestablished beforethestartoftheexperimentalwork. Thereisnointrinsicvalueofenergylosscoefficientforanairhandlingcomponent.Foreachupstreamflow conditionadifferentvaluewillbefou
26、nd.Consequentlytheuseofalongstraightductupstreamofthe componentisjustoneofmanypossibleconditions.Howeverthedifferentlengthsofthisductanddifferent entryconditionscanproducevariations in theflowpattern. Therefore,itisimportanttospecifyindetailallcharacteristicsoftheinstallationupstreamofthecomponent.
27、Theupstreamstraightductshallhavealengthequalto200andaspecifiedperforatedplateattheentrance. Themeasuringsectionshallbelocatedatadistance5Dfromthecomponent. 0123 0123 L 01 L 23CR14378:2002(E) 6 Thedownstreamflowpatternisdependentonthecomponentundertest.Usuallyaverylongstraightductis usedandthemeasuri
28、ngsectionisadistanceawayinordertoallowforthecorrectmeasurement.Theenergy lossoftheductingshallbetakenintoaccountinthecalculationoftheenergylosscoefficientofthe componentundertest.Forthesamelengthofstraightductthisenergylossmaybeverydifferentdepending ontheflowpattern(essentiallyinthepresenceorinthea
29、bsenceofswirl). Astheactuallossisnotknowntheconventionalenergylosscorrespondingtothefullyestablishedflow withoutswirlisnormallyused. Aspecifiedflowstraightener(asusedforfanperformancetestingspecifiedinISO5221)insteadofaverylong duct,(itcanbeaslongas40 D) shallbeinstalledimmediatelydownstreamofthecom
30、ponentundertest.The correctmeasurementofthepressureisthenpossiblewherethelossinthestraightenerandassociated ductingistakenintoaccountconventionally. Animportantadvantageofthismethodistheeliminationofthenecessitytomeasurethekineticenergyfactor A intheupstreamsectionaswellasinthedownstreamsection.Itis
31、assumedthat A isequaltoone.Ifa particularcomponentproducesaverystrongswirlingflowwithanirregularvelocitydistribution,theenergy lossinthestraightenerwillbefargreaterthantheconventionalvalueusedforthecalculation.Theenergyloss coefficientofthecomponentundertestwillappearhigher. Thesecharacteristicsarep
32、resentedinthiswaybecauseinpracticetherotationalenergyinfluidflowwillbe lostanywayandthislossisproducedbythecomponent(thoughnotjnthecomponentitself).Itwillbenoted thatintheusualmethod(alongstraightductdownstream)thisassumptionisalsoappliedbutthe measurementismoredifficultandthescatterofresultsobtaine
33、dindifferentlaboratoriescanbeimportant. 4.2 Testinstallation ThestandardtestinstallationisshowninFigure4. APerforatedplate BUpstreammeasuringsection . CComponentundertest DFlowstraightener“ETOILE EDownstreammeasuringsection FComplementarymeasuring GFlowratecontrolandmeasurement Figure4 Standardtesti
34、nstallation 01 234 A B C D E F G CR14378:2002(E) 7 Thefollowingspecificationshallbeused: a) Ductdiameter:Equaltothediameterofthecomponentundertest b) Perforatedplateattheinlet: diameterofholes: 5mm distancebetweenaxes: 7,5mm freearea/totalarea: 0,40 c) Ductroughness: Smoothmetalduct d) Flowstraighte
35、ner“ETOILE”inaccordancewiththedrawing Length:20(tolerance1%) Thickness:0,0070 Angle: =45 5 4.3 Rectangularandothernoncircularductsandcomponents Forductsandcomponentswithnoncircularcrosssections(essentiallyrectangularandoval)thenotionofa hydraulicdiametershallbeintroduced.Thehydraulicdiameteriscalcul
36、atedasfourtimesthecrosssection dividedbytheperimeter. Forarectangularcrosssectionwithsides aand b,therefore,thehydraulicdiameter D h isgivenby: b a b a b a b a D h 2 2 4 (2) Thestandardtestinstallationshallbemadewithupstreamanddownstreamductsofthesamecrosssection asthecomponentundertest;using D h in
37、steadofDforthecircularduct,allcalculationswillusethesame formulae. Asanalternativesolutionatestinstallationwithcircularductsmaybeused.Thecomponentundertestshall beconnectedtotheupstreamanddownstreamductsusingatransitionwiththefollowingspecification: thecrosssectionareaofthecircularductshallbeequalto
38、thecrosssectionareaofthecomponent withatoleranceof 10%, Thelengthofthetransitionshallbeequaltoonediameterofthecircularduct, Forthecalculationoftheenergylosscoefficientundertest,theenergylossinthetransitionshallbe consideredequaltothelossinastraightducthavingthesamelength. 4.4Measurements Thefollowin
39、gquantitiesshallbemeasured: a) Atmosphericpressure p a ,Pa b) Airtemperature C, T = 273,15 + K c) AirhumidityfrombothdryandwetbulbordewpointtemperatureCR14378:2002(E) 8 d) Staticpressureinthesection0(meanvalueoffourindividualreadings), p s0 Pa e) Static pressureinthesection3(meanvalueoffourindividua
40、lreadings), p s3 Pa f) Differentialpressurebetweenthesection0and3, p s03 Pa g) Staticpressureinthesection4(meanvalueoffourindividualreadings), p s4 Pa h) Massflowrate(byanappropriatestandardizedmethodasgiveninAnnexB), q m kg/s 4.5Calculation method 4.5.1 Thecalculationmethodisgivenin4.5.2to4.5.9 4.5
41、.2 Theabsolutepressuresarecalculatedforthesections0and3asfollows: 0 0 s a p p p (3) 3 3 s a p p p (4) 4.5.3 Themeanairdensity(whichisassumedtobeconstantthroughoutthetestinstallation)iscalculated from: f T p m 287 (5) where 2 3 0 p p p m (6) andthehumidityfactor f isgivenby: m v p p , f 378 01( 7 ) w
42、here p v isthepartialvapourpressure 4.5.4 TheReynoldsnumberiscalculatedfrom: D q m 4 Re (8) wherethedynamicviscosity isgivenby: 6 10 048 0 1 17 , , (9) 4.5.5 Themeanairvelocityiscalculatedfromthefollowing: 2 4 D q v m (10) 4.5.6 ThepressuresinsectionsIand2arecalculatedfromthefollowing: 2 2 01 0 1 v p p (11)CR14378:2002(E) 9 2 2 23 3 2 v p p (12) where 30 0 01 Re 42 0 005 0 5 , , , (13) and 30 0 1
