【正文】 stalled into thegroundcoupled loop, is constructed and tested for the first timeonthebasisofauniversitystudyperformedinthecountry[8–10].(ii)ThetheoreticalperformanceevaluationofahorizontalGSHPwith R22 designed. Although many installations of GSHPsystems worldwide have been realized, the exergetic evaluationstudiesofthesesystemsareverylimited(.[8,11]).This studyalsodescribesaneasytofollowprocedureforexergyanalysisofsolar assisted vertical and horizontal GSHP systems and how toapplythisproceduretoassesstheheatingsystemperformancebycalculating the exergy destructions.2. Description of the systems studiedThe university studies on GSHPs at the Turkish universitiescan be classified into two categories: theoretically andexperimentally. These studies have been reviewed by theauthors in more detail elsewhere [12].. Ground source heat pump system IA schematic diagramof the constructedexperimental systemis illustrated in Fig. 1. This system mainly consists of threeseparate circuits as follows: (i) the ground coupling circuit withsolarcollector(brinecircuitorwater–antifreezesolutioncircuit),Buildings 39 (2020) 66–75 67u usefulv water vaporvalve expansion valvewa water–antifreeze solution(ii) the refrigerant circuit (or a reversible vapour pressioncycle)and(iii)thefancoilcircuitforheating(watercircuit).Themain characteristics of the elements of the solar assisted groundsourceheatpumpsystemaregiveninTable1,wherethenumbers.Conversion from the heating cycle to the cooling cycle isobtained by means of a fourway valve. To avoid freezing thewater under theworking condition and during thewinter, a 10%O. Ozgener, A. Hepbasli/Energy and Buildings 39 (2020) 66–7568groundethyl glycol mixture by weight was prepared. The refrigerantcircuit was built on the closed loop copper tubing. The workingFig. 1. Schematic of the solar assistedstudied was installed at Solar Energy Institute of Ege University(latitude 388240N, longitude 278500E), Izmir, Turkey.Table 1Measured parameters along with their total uncertainties of the ground source heatItemAverage maximum energy consumption of all systemAverage power input to the pressorPower input to each one of the brine and water circulating pumpsTotal power input to the fan of the fancoil unitCurrent of antifreeze solution circulating pump at the ground heat exchanger sideCurrent of the water circulating pump at the fan coil sideMaximum phase to phase voltage (VLL)Average/maximum phase voltages (V/VLN)Average phase to phase voltageTotal maximum current (SA)Frequency (Hz)Average power factor (cos C)Average evaporation/condensation (low/high) pressuresAverage evaporating/condensing temperaturesTemperatures of water at the inlet and outlet of groundheat exchangerAverage temperature of water at solar collector outletSupply/return water temperatures of the fancoil unitVolumetric flow rates of the brine/refrigerantOutdoor/solar collector surface temperaturesOutdoor/laboratory inside design relative humiditiesSolar radiation outside the laboratoryWind velocity at a height of 12 mLength (width) of the collector. Ground source heat pump system IIsource heat pump system [8–10].The GSHP system II theoretically designed as shown inFig. 2. Some similar applications of these systems areavailable in the literature (. [4,13]). It will heat and cool apump system I in average [8–10]Nominal value Unit Total uncertainty (%) kW kW kW kW A A 407 V 220/232 V 380 V A 50 Hz Dimensionless C03/ 8C 8C 52/42 8C C03m3/s 0/10 8C W/m m/s () m gy andtest room with a floor area of 10 m2in Ege University, Izmir,Turkey for the performance test purposes. The heating andcooling loads of the test room are and kW at designconditions, respectively. This system alsowill consist of threeseparate circuits, as explained in the GSHP system I. It differsfrom the first system as follows: (i) a ground heat exchangerO. Ozgener, A. Hepbasli/EnerFig. 2. A schematic of the ground source heat pump system II designed andinvestigated.will be horizontally buried with depths of 1 m, (ii) an aircooled condenser is selected, while the first system has awatercooled condenser, and (iii) the fluid circulating throughthe ground heat exchanger will consist of a 20% ethyl glycolmixture.The theoretical and experimental results evaluated for theGSHP system I are based on the heating seasons of 2020–2020and2020–,thedata usedfortheGSHPIIsystemare obtained from the experimental values [4,13] and theauthors’ assumptions.3. ModellingFor a general steadystate, steadyflow process, the threebalance equations, namely mass, energy and exergy balanceequations,areemployedtofindtheheatinput,therateofexergydecrease, the rate of irreversibility, and the energy and exergyefficiencies [8,11].. Energetic modellingIngeneral,themassbalanceequationcanbeexpressedintherate form as:X˙min188。,withall energy terms as follows:˙Q 254。˙Q。out188。wa240。 (4)The heat rejection rate in the condenser is calculated by:˙Qcond188。 ˙mref240。h2sC0 h1222。 ˙mairCp。air222。˙Qcond(11)Buildings 39 (2020) 66–75 69˙Wp254。wa240。inC0˙Exmass。˙Exdest(14)where˙Qkis the heat transfer rate crossing the boundary attemperature Tkatlocation k,˙Wtheworkrate,ctheflowexergy,h the enthalpy, s the entropy, and the subscript zero indicatesproperties at the restricted dead state of P0and T0.The specific exergy (flow exergy) of refrigerant (or water) isThe exergy rate is calculated by:˙Ex 188。HE188。 ˙mwa240。w188。s C0 s0222。a254。240。C138254。RaT0ln240。1254。1254。1:6078v222。g (16)where the specific humidity ratio is:v 188。˙ExoutC0˙Exin222。cinC0cout222。cinC0cout222。ccold。c