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1、AC-02-15-1PerformanceAnalysisofU-Tube,ConcentricTube,andStandingColumnWellGroundHeatExchangersUsingaSystemSimulationApproachCenkYavuzturk,Ph.D.AndrewD.Chiasson,P.E.MemberASHRAEABSTRACTtheirconventionalalternatives.Despitetheseadvantages,commercialgrowt
2、hofthetechnologyhasbeenhinderedbyThedesignlengthofgroundheatexchangersforgeother-highcapitalcostsofthesesystems,ofwhichasignificantmalheatpumpsystemsisstronglydependentontheboreholeportionisattributedtotheground-loopheatexchanger.thermalresistance.Theb
3、oreholethermalresistanceisdefinedbythethermalpropertiesofthematerialsofconstructionandIndesignanddimensioningofground-sourceheatpumpthearrangementofflowchannelsofthegroundheatexchangersystems,theboreholethermalresistanceisanimportantandstronglyinfluenc
4、estheperformanceofageothermalheatparameterthataffectsbothshort-andlong-termtemperaturepumpsystem.Simulationstudiesarepresentedthatexamineresponsesoftheheatpumpsystemand,consequently,hasaandcomparethethermalperformanceofsomeofthemorestronginfluenceonthe
5、designlengthofthegroundheatcommontypesofgroundheatexchangers,suchassingleU-exchanger.Theboreholethermalresistanceisdefinedbyatube,doubleU-tube,concentrictube,andstandingcolumnnumberofdesignvariables,includingthecompositionandwell(withnogroundwaterbleed
6、),usingamathematicalflowrateoftheheattransferfluid,boreholediameter,heatdescriptionforthethermalresistanceofgroundheatexchang-exchangerpipematerial,arrangementoftheflowchannels,ers.Thesystemsimulationsarebasedonashorttimestepandgroutmaterial.Thegreater
7、thethermalresistanceofthegroundheatexchangermodelandareconductedunderanindividualboreholeelements,thelesswillbetheheattransferequivalentsetofconditionsconsideringasmallofficebuild-ratebetweentheheatcarrierfluidandtheearth,thusrequiringing.Resultsshowth
8、atthesingleU-tuberequiresthegreatestanincreasedlengthofthegroundheatexchanger.Giventhatlengthofborefortheconditionssimulated.Theoreticalreduc-thegoalofthedesignengineeristominimizecapitalcostsoftionsintotalborelengthofapproximately22%,3