Effect of a superheating and sub-cooling heat exchanger to the performance

Energy44(2012)996e1004

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Energy

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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