Energy44(2012)996e1004
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Effectofasuperheatingandsub-coolingheatexchangertotheperformanceofagroundsourceheatpumpsystem
KadirBakirci*,DeryaColak1
DepartmentofMechanicalEngineering,AtatürkUniversity,25240Erzurum,Turkey
articleinfo
Articlehistory:
Received15November2011Receivedinrevisedform13April2012
Accepted20April2012
Availableonline7June2012Keywords:
GroundsourceheatpumpGroundheatexchangerColdclimateHeating
SuperheatingSub-cooling
abstract
Theaimofthisstudyistoevaluatetheeffectofasuperheatingandsub-coolingheatexchanger(SHCHE)totheperformanceofgroundsourceheatpumpsystemforclimaticconditionofErzurumhavingcoldclimateinTurkey.Forthispurpose,anexperimentalset-upwasconstructed.Theexperimentalapparatusconsistsofaseriesgroundheatexchanger(GHE),aliquid-to-liquidvaporcompressionheatpump,watercirculatingpumpsandothermeasurementequipments.Inthisstudy,theperformanceofthesystemswithandwithoutSHCHEwasexperimentallyinvestigated.Theexperimentswereperformedin2010forJanuaryandFebruarywhicharethecoldestmonthsoftheheatingseason.Theexperimentallyobtainedresultswereusedtocalculatethepowervaluesofthemainsystemequipments,thecoef cientofperformanceoftheheatpump(COP)andtheoverallsystem(COPS)forsystemswithandwithoutSHCHE.
Ó2012ElsevierLtd.Allrightsreserved.
1.Introduction
Turkey’sdemandforenergyandelectricityisincreasingrapidly.Turkeyisheavilydependentonexpensiveimportedenergyresourcesthatplaceabigburdenontheeconomy.Aswouldbeexpected,therapidexpansionofenergyproductionandconsumptionhasbroughtwithitawiderangeofenvironmentalissuesatthelocal,regional,andgloballevels.Withrespecttoglobalenvironmentalissues,Turkey’scarbondioxide(CO2)emissionshavegrownalongwithitsenergyconsumption.Stateshaveplayedaleadingroleinprotectingtheenvironmentbyreducingemissionsofgreenhousegases.Inthisregard,renewableenergyresourcesappeartobeoneofthemostef cientandeffectivesolutionsforcleanandsustainableenergydevelopmentinTurkey.Turkey’sgeographicallocationhasseveraladvantagesforextensiveuseofmostoftheserenewableenergysources[1].
Infuturetheworld’senergysupplymustbecomemoresustainable.Thiscanbeachievedbothbyamoreef cientuseofenergyandbyrelyingonrenewablesourcesofenergy,particularlywind,hydropower,solarandgeothermalenergy[2].Turkeyisan
*Correspondingauthor.Fax:þ904422360957.E-mailaddress:abakirci@atauni.edu.tr(K.Bakirci).1
Presentaddress:Directoryofthe12thRegionofHighways,25080Erzurum,
Turkey.
0360-5442/$eseefrontmatterÓ2012ElsevierLtd.Allrightsreserved.doi:10.1016/j.energy.2012.04.049
energyimportingnationwithmorethanhalfofourenergyrequirementsmetbyimportedfuels.Airpollutionisbecomingasigni cantenvironmentalconcerninthecountry.Achievingsolutionstoenvironmentalproblemsthatwefacetodayrequireslong-termpotentialactionsforsustainabledevelopment.Forthegovernmentsorsocietiestoattainsustainabledevelopment,muchefforthastobedevotedtoutilizingsustainableenergyresourcesintermsofrenewableenergies[3,4].
TheGSHP(groundsourceheatpump)isoneoftheef cientandsustainablemethodstoprovidespaceheatingandhotwaterforvariouskindsofbuildings.TheGSHP,worksbymeansofthevaporcompressioncycle,whichcoolsacirculating uidthat owsthroughasystemofclosedloops.Theseloopsareburiedwithinthegroundeitherhorizontally,iflandspacepermits,orverticallybymeansofboreholes.Thedirectionofheat owisfromthegroundtothecooler uidandthisheatisupgradedtoahighertemperaturethroughthevaporcompressioncyclefordeliverytothebuilding[5].Thegroundsourceheatpumpsprovideanewandcleanwayofheatingbuildingsintheworld.Theymakeuseofrenewableenergystoredintheground,providingoneofthemostenergy-ef cientwaysofheating.Theyaresuitableforawidevarietyofbuildingtypesandareparticularlyappropriateforlowenvironmentalimpactprojects[6].
Intheliterature,anumberofinvestigationshavebeencon-ductedbysomeresearchersinthedesign,modelingandtestingoftheGSHPsystems[7e18].HealyandUgursal[8]haveinvestigated
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theeffectofvarioussystemparametersontheGSHPperformanceusingacomputermodel.TheyhavealsocarriedoutacomparativeeconomicevaluationtoassessthefeasibilityofusingaGSHPinplaceofconventionalheating/coolingsystemsandanairsourceheatpump.Floridesetal.[9]carriedoutastudyonthegeothermalcharacteristicsofthegroundandthepotentialofusinggroundcoupledheatpumpsinCyprus.Yuetal.[11]designedaconstanttemperatureandhumiditysystemdrivenbyagroundcoupledheatpumpandconstructedinanarchivesbuildingofShanghai.TheexperimentalresultsunderweatherconditioninShanghaiwereanalyzedand,theinvestigationoftheexperimentinayearwaspresented.Pulatetal.[15]haveinvestigatedtheperformanceofthehorizontalclosed-loopwater-to-airgroundsourceheatpumpsystemincludingtheeffectofvariousparameterssuchasleavingtemperatureofgroundheatexchangerunitandoutdoortemper-atureforwinterclimaticconditionofBursa,Turkey.Blumetal.[16]determinedandassessedtheeconomicandtechnicalfactorsthatin uencethedesignandperformanceoftheGSHPsystemsinprivatehouseholds.