Effect of a superheating and sub-cooling heat exchanger to t(5)

ThedailyaveragevaluesofthemeasureddataandcalculatedresultsaregiveninTable4.Thesevaluesconsistoftheaveragevaluesofthemeasurementsof21recordedfrom8.00a.m.to18.00p.m.withanintervalof30min.AsseeninTable4,thecondensationpressuresinaverageareabout15barand,thisvalueisveryreasonablebecausethemaximumdischargepressurelimitofthecompressoris29bar.

8

8

6Teai-Teao (°C)

6Teai-Teao (°C)

44

2

2

008:00

10:00

12:0014:00Time of day

16:0018:00

008:00

10:0012:0014:0016:0018:00

Time of day

With(Jan. 20)andwithout (Jan. 23)SHCHEWith(Feb. 05)andwithout(Feb. 03)SHCHE

Fig.6.Variationsininlet-outlettemperaturedifferences(TeaiÀTeao)oftheantifreeze-watersolutiontotheGHEunitwithtimeofdayforthesystemswithandwithoutSHCHE.

K.Bakirci,D.Colak/Energy44(2012)996e1004

1003

Table4

MeasuredandcalculatedparametersinaverageforthesystemwithoutSHCHE(January23,2010andFebruary03,2010).Item

Jan.23,Feb.03,Unit

Total

2010

2010

uncertainty(%)MeasuredparametersEvaporationpressure2.642.59BarÆ2.05Condensationpressure14.7714.69BarÆ2.05Temperatureofrefrigerant2.351.52 C

Æ1.01atthecompressorinletTemperatureofrefrigerant81.2781.31

CÆ1.01atthecondenserinletTemperatureofrefrigerant48.4347.73

CÆ1.01atthecondenseroutletTemperatureofrefrigerantÀ7.83À8.24

C

Æ1.01attheevaporatorinletCondensingtemperature54.6054.38

CÆ1.01EvaporatingtemperatureÀ2.95À3.46

CÆ1.01Flowrateofantifreeze-water0.2880.333kgsÀ1

Æ7.15solutionintheevaporatorFlowrateofwaterinthe0.267

0.324

kgsÀ1

Æ7.15

heatingunitorthecondenser

Indoorairtemperature

11.749.73

CÆ1.01Currentofcirculatingpump0.600.60AÆ1.00attheGHE

Currentofcirculatingpump0.690.69AÆ1.00attheheatingunitTwo-phasevoltage220.0220.0VÆ1.00Temperatureof

1.74

1.11

C

Æ1.01

antifreeze-watersolutionattheevaporatorinletTemperatureof

À2.30À2.65

CÆ1.01

antifreeze-watersolutionattheevaporatoroutletSupplywatertemperature49.5648.41

CÆ1.01oftheheatingunit

Returnwatertemperature45.1144.68

C

Æ1.01oftheheatingunit

Powerinputtothecompressor2.001.85kWÆ1.00Calculatedparameters

Powerinputtothecirculating0.1190.119kWÆ3.00pumpattheGHE

Powerinputtothecirculating0.1370.137kWÆ3.00pumpattheheatingunitHeatingloadofthecondenser4.9555.207kWÆ7.23Coolingloadoftheevaporator3.6023.907kWÆ7.23HeatingCOP(theheatpump)

2.4702.809eÆ7.30HeatingCOPS(theoverallsystem)

2.190

2.621

e

Æ7.28

6.Conclusions

Theperformanceofaverticalgroundsourceheatpumpsystemwasinvestigatedexperimentally.Inthestudy,theexperimentalresultsweregivenforthemonthsofJanuaryandFebruaryintheheatingseasonof2010.TheexperimentalresultsindicatethattheaveragevaluesoftheCOPandtheCOPSareapproximately2.31and2.07withSHCHEand2.47and2.19withoutSHCHEinJanuary,whiletheyareapproximately2.73and2.55withSHCHEand2.81and2.62withoutSHCHEinFebruary,respectively.Additionally,theresultsshowthatthesystemswithandwithoutSHCHEarenotverydifferentintermsofthecoef cientofperformancebutthesystemwithSHCHEcanbepreferredforhighercondenseroutlettemperature.

Theheatpumpsystemsareenvironmentallyfriendly.Theinitialcostsoftheheatpumpsystemsarehigher,buttheyhavelowoperating,maintenance,andlifecyclecostsandalongerlifeexpectancythanmostconventionalsystems.Also,theheatpumpsystemsprovideheating,coolingandhotwaterinmanyapplications.Thegroundsourceheatpumpsystemspresent

tremendousenvironmentalbene tswhencomparedtotheconventionalsystems.Therefore,thesesystemscanbeusedtominimizeenvironmentalimpactsandairemission.

Acknowledgment

TheauthorsthanktheAtatürkUniversityResearchFund(ProjectNo:2005/25)andTheScienti candTechnologicalResearchCouncilofTurkey(TUBITAK,ProjectNo:106M068)duetotheir nancialsupportforthisresearch.

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