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ID:36776599
大小:320.87 KB
页数:6页
时间:2019-05-15
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1、ChrisChampagneAE597JHomework#1ComputationalFluidDynamicsandDoubleSkinFacadesIntroduction:IntheHVACfield,thereisaneedtovalidateaproposeddesigntoensureproperperformance.Oneoftwomethodsistypicallyused:experimentalornumerical.Althoughexperimentalvaluesareveryreliablewhenperformedinacontrolledenvironme
2、nt,thereareseveralmajordrawbackstothisapproach.Itisexpensiveandtimeconsuming.ComputationalFluidDynamics(CFD)isanumericalapproachthatisinformativewhilealsosavingtimeandmoney.Experimentscanberepeatedmorerapidlytoensureaccuracyandtoslightlyaltervariablestoseehowperformanceisaffected.Thethermalenviron
3、mentofaspacecanbedescribedusingthevelocity,temperature,pressureandsmokeconcentrationdiagramsthatCFDcanproduce.ThedrawbacksofCFDarethattheprogramsusedrequireacomputerwithlargeamountsofmemoryandprocessorspeedandtobetrulyaccurate,theCFDresultsmustbeverifiedexperimentally.DoubleSkinFacades:Thebuilding
4、thatIamstudyingformyseniorthesisistheManulifeFinancialU.S.OperationsHeadquartersinBoston,Massachusetts.Oneofthemostuniquefeaturesofthebuildingisitsexteriorfacade.Itisafullyglazed8"doubleskincurtinwallfaçade(alsoknownbyseveralothernamesincludingactivewallandventilatedcavitywall).Thistechniqueispopu
5、larinEuropebuthasnotusedveryoftenintheUnitedStates.Themainadvantageofaddingasecondsheetofglassbehindthedoubleglazingisthetemperaturedifferencesbetweentheairintheroomandthesurfaceoftheglasswallisreduced.Thisimprovesthethermalcomfortconditionsintheofficespaceneartheexteriorwallsandalsoreducesenergyc
6、ostsforheatinginwinterandcoolinginsummer.Theheatinsulationpropertiesarebetterthanthatofanormal,doubleglazing,becauseoftheextrainsulatingpropertiesoftheventilatedcavity.AnexampleofasimplifiedtypeofthisfacadecanbefoundinFigure1.CFDApplication:CFDcanbeusedtogaininsightintomultipleglazingperformancean
7、dalsooptimizethedesignandoperationofmultipleglazingsystemssuchasairflowwindowsordoubleskinfacadesintermsofenergyefficiencyandthermalcomfort(Gan,2001).Airflowandheattransfercanbedemonstrated.CFDcanbeusedtopredictt
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