Research Article Performance Assessment of a …downloads.hindawi.com/journals/ijce/2016/5710560.pdfCV = in out, CV = + + in out , CV = 0 1 + + 0 CV + in out CV, whereexergyofanystream

Research ArticlePerformance Assessment of a Hybrid Solar-Geothermal AirConditioning System for Residential Application EnergyExergy and Sustainability Analysis

Yasser Abbasi Ehsan Baniasadi and Hossein Ahmadikia

Department of Mechanical Engineering Faculty of Engineering University of Isfahan Hezar Jerib AvenueIsfahan 81746-73441 Iran

Correspondence should be addressed to Ehsan Baniasadi ebaniasadienguiacir

Received 4 December 2015 Revised 7 January 2016 Accepted 12 January 2016

Academic Editor Pouria Ahmadi

Copyright copy 2016 Yasser Abbasi et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

This paper investigates the performance of a ground source heat pump that is coupled with a photovoltaic system to provide coolingand heating demands of a zero-energy residential building Exergy and sustainability analyses have been conducted to evaluate theexergy destruction rate and SI of different compartments of the hybrid system The effects of monthly thermal load variationson the performance of the hybrid system are investigated The hybrid system consists of a vertical ground source heat exchangerrooftop photovoltaic panels and a heat pump cycle Exergetic efficiency of the solar-geothermal heat pump system does not exceed10 percent and most exergy destruction takes place in photovoltaic panel condenser and evaporator Although SI of PV systemremains constant during a year SI of GSHP varies depending on cooling and heating mode The results also show that utilizationof this hybrid system can reduce CO

2emissions by almost 70 tons per year

1 Introduction

Theenergy consumption for residential applications is almostone-third of the worldrsquos primary energy demand while it israpidly increasing due to population growth and improve-ment in human life standards [1 2] Currently most ofthe required energy in this sector is supplied by high-temperature sources to meet low-temperature heating needsThese energy crises besides environmental degradation ofearth global warming and depletion of natural resourceshave encouraged researchers to investigate the possibility ofusing environmentally benign energy resources to drive lowexergy systems that is solar systems ground source heatexchangers and so forth with working temperatures close toenvironment temperature Low exergy systems are basicallyair conditioning systems that utilize low grade energy ofsustainable sources to provide heating and cooling effects ata temperature close to room temperature [3]

As a promising approach in energy conservation heatpumps can be combined with renewable energy sources toprovide a low exergy cooling and heating system Among the

renewables geothermal wind and solar are more adoptableto sustainable buildings Most of the research and devel-opments in renewable energy based systems for residentialapplication are conducted to provide hot water heatingcooling and ventilation by heat pumps or vapor-powercycles [4ndash6] Ground source heat pumps (GSHP) integratedwith certain types of low-temperature distribution systemhave been identified as the most efficient and ecofriendlyheating and cooling technology for various climates Thesesystems are energy efficient and they are designed basedon the relatively constant temperature of the ground tosupply heating during the winter and cooling during thesummer Vertical closed-loop systems are the most efficientthough themost expensive configuration because the subsoillevel of temperature increases and stabilizes with depth[7ndash9] Analyses of GSHP have been widely conducted inliterature from energetic and exergetic points of view [10ndash13]Integration of ground source heat pumps with photovoltaicsystem is a promising option to supply electricity hot waterand heating and cooling effects for off-network communitiesand remote areas [14ndash16]

Hindawi Publishing CorporationInternational Journal of Chemical EngineeringVolume 2016 Article ID 5710560 13 pageshttpdxdoiorg10115520165710560

2 International Journal of Chemical Engineering

Combination of different renewable energy sources tomeet the demands of a sustainable building is widely studiedLi et al [17] described a rooftop hybrid heat pump systemthat uses wind and solar energy to provide hot water heatingand cooling from energy exergy and environmental pointof view Mikati et al overviewed a small-scale distributedpower system that contains photovoltaic arrays small-scalewind turbines and an electric grid connection [18] Dai etal conducted an experimental study to evaluate the effectof operation modes on the heating performance of a solarassisted ground source heat pump system (SAGSHPS) [19]Moreover different concepts of solar assisted heat pumpsystems with ground heat exchanger are simulated accordingto IEA SHC Task44HPP Annex38 reference conditionsusing TRNSYS softwareThe dependency of system efficiencyon seasonal performance factor and possible shortening ofthe ground heat exchanger by minimum temperature atthe ground heat exchanger inlet are evaluated [20] Theperformance of a new system for cooling of solar PV panelscalled Ground-Coupled Central Panel Cooling System (GC-CPCS) which is in operation at the Energy Park of RajivGandhi Proudyogiki Vishwavidyalaya (RGPV) is studiedby Sahay et al [21] Exergy analysis of photovoltaic systemhas been conducted broadly Sobhnamayan et al [22] haveinvestigated an optimized solar photovoltaic thermal (PVT)water collector based on exergy concept Exergy analyses ofphotovoltaic (PV) and photovoltaicthermal (PVT) systemswere presented by Saloux et al [23] Gholampour et al[24] have evaluated the performance of the PVUTC andUTC systems by introducing energy efficiency as a functionof electrical-to-thermal ratio number and also the secondlaw efficiency Exergy and economic evaluation of thermalphotovoltaic (PVT) water based collectors for differentclimates in Iran have been conducted by Jahromi et al [25]

In this study an exergy analysis is conducted to investigatethe performance of an integrated PV-GSHP system forspace heating and cooling of a remote building A generalarrangement schematic view of the system is illustrated inFigure 1 The required area of SPV panels and GSHP neededlength are calculated for the hybrid air conditioning systemof a 200m2 building in a remote area The effect of differentclimates on system performance is investigated based on themeteorological data of three cities of Iran (Isfahan Yazdand Shahrekord) It is assumed that the building structureis identical for all climate case studies however the coolingand heating loads solar irradiation and ground depth tem-perature are different The analysis is based on the monthlyaveraged energy demands of the building It is assumed thatheat and electricity can be stored during daytime An energyexergy and sustainability analysis is conducted to evaluate thefeasibility of utilizing solar assisted ground source heat pump(GSHP) for air conditioning purposes

2 System Analysis

21 Heating and Cooling Load A remote building with200m2 area located in Isfahan (elevation 1590m) is consid-ered to study the performance of an integrated geothermalheat pump and photovoltaic system that provides heating and

Battery groups

Solar irradiation Photovoltaic panel

N

(electricity storage)Heat pump

unit

Gro

und

sour

ce h

eat e

xcha

nger

Figure 1 Schematic viewof the solar assistedGSHPair conditioningsystem

cooling loads The system performances are compared fordifferent cities of Iran including Yazd (elevation 1216m) andShahrekord (elevation 2061m) Figure 1 shows a schematicview of the residential building and the solar assisted geother-mal heat pumpThe heating cooling and hot water demandsof the building are calculated based on outdoor designconditions of each city on an hourly basis

22 System Description Figure 3 shows a flow diagram of theintegrated solar assisted GSHP system that operates as an off-grid energy system for the specified residential building Itconsists of three main loops

(1) The ground loop delivers heat energy (in coolingmode) to ground sublayers or takes heat energy (inheating mode) from the ground A circulating pumpcirculateswater as aworking fluid in the loop (stream1) Heat is exchanged with the ground via a networkof 119899 number of GSHXs with overall efficiency of 120578

119892119909

The ground temperature 119879119892is almost constant during

a year(2) The primary loop is basically a Rankin refriger-

ation cycle that consists of two heat exchangerswith exchangeable functions depending on coolingor heating season In heating mode the first heatexchanger takes heat from the ground loop as anevaporator while the other heat exchanger deliversheat to the secondary loop as a condenser In coolingmode the first heat exchanger delivers heat to theground loop as a condenser and the other extractsheat from the secondary loop as an evaporatorA compressor pressurizes refrigerant R-134a in theprimary loop A 4-way valve is adopted to switch

International Journal of Chemical Engineering 3

cooling and heating mode functions by reversing therefrigerant flow direction

(3) The secondary loop exchanges heat via a fan-coilheat exchanger with the air conditioned space Apump is used to circulate water through the loopThe photovoltaic system supplies the required electricpower of pumps compressor and the fan-coil Thissystem includes PV panels convertor and batteriesThe batteries store the generated electricity by the PVsystem during daytime

3 Energy and Exergy Analyses

The following assumptions are considered for calculatingenergy and exergy of the streams

(a) All of the processes are steady

(b) Potential and kinetic energy of the streams are negli-gible and no chemical reactions exist

(c) The compressor mechanical and electrical efficienciesare 80 and 70 respectively

(d) Air is an ideal gas and its specific heat is constant

(e) The dead state conditions are selected as 1198790= 10∘C

and 1198750= 101325 kPa

(f) The thermodynamic properties of water air and R-134a are calculated using the EES software package

(g) The mass flow rate calculations are made by EESsoftware

The case studies are also performed based on the assumptionsin Table 1

31 Ground Source Heat Pump Based on the aforementionedassumptions mass energy and exergy balance equationsare applied to find the output power heat gain rate ofexergy destruction and energy and exergy efficiencies Thegoverning equations are as follows [26 27]

119889

119889119905(119872CV) = sum

in minussum

out

119889

119889119905(119864CV) = + +sum

inℎ minussum

outℎ

119889

119889119905(ΦCV) = [sum

119894(1 minus

1198790

119879119894

)] + [ + 1198750

119889

119889119905(forallCV)]

+sumin120595 minussum

out120595 minus CV

(1)

where exergy of any stream (120595) is defined as

120595 = (ℎ minus ℎ0) minus 1198790(119904 minus 1199040) +

1198812

2+ g119911 (2)

Table 1 Main assumptions for analysis (Isfahan case study monthof January)

Parameter ValueGeneral parametersDesign temperature 225 (∘C)Dead state temperature 10 (∘C)Ground temperature 17 (∘C)Thermal load 101 (kW)Solar irradiance 02 (kWmminus2)Battery efficiency 70Power conversion efficiency 18GSHX parametersWorking fluid WaterInlet temperature 5 (∘C)Outlet temperature 15 (∘C)Soil resistance 230 (kWminus1m ∘C)Ground pump efficiency 80Ground heat exchanger efficiency 80Heat pump parametersEvaporator pressure 200 (kPa)Condenser pressure 800 (kPa)Refrigerant R-134aCondenser efficiency 80Evaporator efficiency 80Compressor efficiency 80Expansion valve efficiency 80Room heater parametersWorking fluid WaterInlet temperature 20 (∘C)Outlet temperature 30 (∘C)Fan-coil heat exchanger efficiency 80Fan-coil pump efficiency 80

311 Heat Transfer Process in Fan-Coil Therate of exergy thatis delivered to room due to thermal (Φload) is

Φload = load (1 minus1198790

119879119889

) (3)

where load is the heating or cooling load of the buildingand 119879

119889is indoor design temperature of the building The

irreversibility rate in the air conditioning heat exchanger is

fan-coil = Φload plusmn (120595in minus 120595out) (4)

312 Compression Process In the hybrid cycle the inputexergy required for compression process either in pumpsor in compressor is delivered from the photovoltaic systemwith energy efficiency of 15 percent By neglecting frictionalheating the rate of irreversibly for compression process is

pump = pump + (120595in minus 120595out) (5)

The irreversibility due to energy conversion deficiency inelectric motors can be written as

electric-motor = PV (1 minus 120578119901119890) (6)


minus5

0

5

10

15

20

25

30

35

40

45

50

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Yazd_T_GYazd_T_EShahrekord_T_G

Shahrekord_T_EIsfahan_T_GIsfahan_T_E

Tem

pera

ture

(∘C)

(a)

0

5

10

15

20


Load

s (kW

)

Shahrekord_CoolingYazd_CoolingIsfahan_Cooling

Shahrekord_HeatingYazd_HeatingIsfahan_Heating

(b)

Figure 2 Monthly variations of environment and ground temperature for different cities (a) and corresponding cooling and heating loadscalculated with available software (b)

313 Evaporator and Condenser Exergy balance for thisprocess is given by

CV = sumin120595 minussum

out120595 (7)

Thus evaporator or condenser lost exergy is

119890119888= (11205951in + 21205952in) minus (11205951out + 21205952out) (8)

314 Throttling Process The exergy loss rate CV in thethrottling valve is

tr = (120595in minus 120595out) (9)

315 Ground Source Heat Exchanger The exergy rate that isextracted from ground Φgeo is

Φgeo = geo (1 minus1198790

119879geo) (10)

where geo is the exchanged heat between the ground andthe working fluid in the heat exchanger loop and 119879geo is theaverage ground temperature in a specific depth

The ground temperature 119879geo is a function of severalparameters It can be calculated using the following equation

119879geo = 119879mean + 1198601015840 cos(120596 (119905 minus 119905

0) minus

119911

119889) times 119890minus119911119889

(11)

where119879mean is annual average temperature (∘C)1198601015840 is temper-ature wave magnitude (∘C) 120596 is temperature wave frequency[2120587(365times24 hours)] 119905

0is time for the warmest day of a year

(hour) 119911 is ground depth (m) and 119889 = radic2120572120596 in which 120572 isheat conductivity of soil (m2hour)

The pipe length of GSHX is calculated by

119871GSHX =geo

119879geo minus 119879119882119866

1

119877tot (12)

where 119877tot is the total thermal resistance of soil pipe andwater and 119879

119882119866is the mean temperature of water flowing

through ground source heat exchanger Considering physicalproperties of polyethylene pipe soil and water the totalthermal resistance is 119877tot asymp 230 kWm

∘CThe exergy destruction rate in the heat transfer process is

GSHX = Φgeo + (120595in minus 120595out) (13)

32 Photovoltaic System Solar Irradiance is ameasure of howmuch solar power can be delivered at a specific locationFigure 4 illustrates the monthly solar irradiation averagedover 22 years for different cities Figure 4 provides theinformation on the available solar irradiation in case of usingPV panel with sun tracking based on [28] This informationis then used to calculate the average daily power generationfrom the photovoltaic system in each month

The actual energy input from solar radiation may bedefined as below [23]

solar = 119860119868119904 (14)

where 119868119904is solar irradiance intensity and is 119860 photovoltaic

panel net area


1

2

3

(2) Evaporator (cooling mode)

Condenser (heating mode)

4

Compressor

g1

g2

g3

r1

r2

r3r4

h3

h2

h1

g (ground flow)r (refrigerant flow)h (home flow)

Ground loop pump

GSHX

Expansion valve

Secondary loop pump

(1) Evaporator(heating mode) Condenser(cooling mode)

Fan-coilheat exchanger

4-wayvalve

Con

vert

or an

d co

ntro

ller

Solar PV panel

(1) GSHX water cycle(2) Refrigerant flow cycle(3) Home water cycle(4) Electricity circuit

Figure 3 Flow diagram of the integrated solar assisted GSHP system

The input exergy of solar radiation is given by [29]

Φinsolar = (1 minus4

3(1198790

119879119904

) +1

3(1198790

119879119904

)

4

) 119868119904119860 (15)

where 119879119904is the sun temperature and is taken as 5777K The

exergy balance for the PV module can be written to find theassociated irreversibility as follows [30ndash32]

Φinsolar = PV + PV (16)

It is shown that PV output exergy can be calculated as

PV = 119881119898119868119898 (17)

where 119881119898is PV voltage and 119868

119898is generated current

The energy conversion efficiency of PV module can bedefined as the ratio of the net electrical output power to theinput energy as below

120578pce =119881119898119868119898

119868119904119860 (18)

33 Overall System Analysis The input exergy to the hybridcycle is received from the geothermal source (Φgeo) and pho-tovoltaic system (ΦPV) The desired exergy that is deliveredto the house isΦload Therefore the second low efficiency forthe hybrid cycle is

120578II =Φload

Φgeo + ΦPV (19)


0

1

2

3

4

5

6

7

8


ShahrekordIsfahanYazd

Mon

thly

aver

age i

rrad

iatio

n (k

Wh

m2

dayminus

1)

Figure 4 Monthly average solar irradiation for different cities

Total exergy losses are calculated by

total = GSHX + evaporator + condenser + tr

+sum(pump + electric-motor) (20)

34 Sustainability Analysis Exergy analysis can be furtherextended to investigate the sustainability of the cycle either atdesign stage or for the existing condition The sustainabilityindex gives useful information about how exergy efficiency ofsubsystems affects the sustainability of the energy resourcesand overall system Higher sustainability index indicatesmore sustainability of the process or systemThe sustainabil-ity index (SI) is defined as [29]

SI = 1

1 minus Ψ (21)

where

Ψ =output exergyinput exergy

(22)

It is also useful to investigate the performance of the sub-systems using relative irreversibility (RI) that is the ratio ofthe subsystem exergy destruction rate

119904to the overall system

exergy destruction rate tot

RI =119904

tot (23)

4 Results and Discussions

41 Exergy Flow Diagram Figure 5 illustrates a Grassmanndiagram of the hybrid systemThe flow of exergy from energysources for example solar and geothermal energy usefulexergy delivered to building and exergy destruction areshown quantitativelyThe results are related based on Isfahan

climate in January It can be concluded that most exergydestruction takes place in photovoltaic modules Around82 of the total incident solar exergy is captured by thephotovoltaic system of which about 76 is destroyed dueto energy conversion deficiencies of the PV panels From24 of the input solar exergy that is delivered to the batterystorage compressor and pumps about 15 is destructeddue to irreversibility in these components as well as AC-DC converter Therefore almost 10 of solar irradianceexergy would be converted to useful work in the pumps andcompressor Improvement in energy conversion efficiency ofthemechanical and electrical equipmentrsquos and heat exchangerredesign can avoid exergy losses to some extent On theother hand about 67 of the total input exergy from GSHPsystem that is delivered to the evaporator condenser andother heat exchangers is lost due to irreversibility in heattransfer processes

42 Exergy Efficiency The variation of exergy efficiency ofthe system during a year is illustrated in Figure 6 The exergyefficiency of the hybrid cycle is almost constant during thehot season and it is at its lowest value of 2 During the coldseason however the efficiency of the system would increaseThe exergy efficiency is highly dependent on the GSHPperformance During hot seasons ground temperature andambient temperature are more close to each other comparedto the cold season It will cause low geothermal exergyinput during the hot season Although during cold seasonscooling mode and ambient temperature are so variable (incomparison to the hot season) ground temperature remainsnearly constantThis fact causes a variable geothermal exergyinput in cold seasons As solar exergy is relatively less variableduring cold seasons exergy efficiency of the system is highlydependent on geothermal subsystem exergy efficiency Onthe other hand the highest exergy efficiency values are forthe coldest season of Jan and Dec During these seasons thegeothermal system has a better performance because of thehighest difference between ground depth temperature andambient temperature in cold seasons

43 Sustainability and Relative Irreversibility Analysis Fig-ures 7 and 8 represent the sustainability index of the twomain energy harvesting compartments namely photovoltaicand geothermal systems as well as the integrated cycle Asexergy input from the solar system is far greater than thegeothermal system (due to extensive destruction of PV sys-tem) sustainability index of the integrated system is relativelyconstant as the solar system It can be observed from Figure 7that PV system sustainability has limited dependency on deadstate temperature It can be also concluded from (15) thatthe difference between temperature of the sun and dead statetemperature compensates the effect of this parameter on theinput exergy from the sun to the PV system As shown inFigure 8 the PV system sustainability index is 12 during ayear On the other hand the sustainability index of GSHPsystem is a function of dead state temperature Since in thisstudy the ground temperature is taken as 17∘C the GSHPsustainability index isminimumwhendead state temperature


54

6

8

1

2

7

3

(1) Solar exergy (142 kW)

(2) Geothermal exergy (31kW)

(3) Exergy loss in PV system (104 kW)

(7) Delivered exergy (heating mode) (12 kW)

(8) Exergy loss in heatexchangers (21 kW)

(4) Exergy loss inbattery (08 kW)

(5) Exergy loss in AC-DCconvertor (082 kW)

(6) Exergy loss in compressorand pumps (04 kW)

Figure 5 Grassmann diagram for hybrid cycle in heating mode (without scale)

0

1

2

3

4

5

6

7

8

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

120578II

()

Figure 6 Exergy efficiency of integrated SPV and GSHP fordifferent months

is 15∘C Sustainability index of GSHP will be constant duringthe hot season (cooling mode) because the design indoortemperature and ground temperature are close to each otherand ambient temperature changes are limited During thecold season as the ambient temperature decreases the sus-tainability of GSHP increases It shows that the hybrid cycle

1

11

12

13

14

15

16

17

18

0 5 10 15 20

SI

Dead state temperature (∘C)

SI_PVSI_GSHP

Figure 7 Sustainability index of the GSHP and PV systems versusdead state temperature

is more sustainable and exergy destruction is lower in thecold season However during April and October months dueto the close environment temperature to the indoor design


1

105

11

115

12

125

13

135

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

SI

SI_PVSI_GSHX

Figure 8 Sustainability index of the GSHP and PV systems duringa year

PV (76)

PCE (6)GSHX (2)

Heat exchangers (12)

Compressor (3)

Throttling (1

)

Figure 9 Relative irreversibility of components

temperature the cooling and heating loads are much smallerthan the cycle capacity and the output exergy decreasessignificantly comparing with input exergy In fact the hybridcycle irreversibilityrsquos and exergy destruction increase andits sustainability index are of minimum value during thesemonths

Figures 9 and 10 illustrate the relative irreversibility of theunitsprocess for the entire cycle and the GSHP subsystemrespectively It is shown in Figure 9 that most exergy destruc-tion takes place in the PV system The photovoltaic cellsAC-DC converter and battery system destruct about 82 ofoverall input exergy (119868 PV + 119868 PCE) The next most exergydestructive process is related to heat exchange in evaporatorand condenser These two processes destruct almost 12 ofthe total input exergy Figure 10 indicates that about 70 of

Throttling (6)

GSHX (10

)


Compressor and pumps(15)

Figure 10 Relative irreversibility of GSHP components

0

05

1

15

2

25

3

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)

UnavoidableAvoidable

Figure 11 Exergy destruction rate of GSHP system during a year

the exergy destruction in GSHP is due to heat exchange incondenser and evaporator

44 Design Constraint Effects The main design constraintsof the hybrid cycle are the length of ground source heatexchanger and the PV panelrsquos area Any design criteria forthese parameters can change the exergy analysis resultsClimate characteristics can also affect the performance of thesystem The COP of the system is a function of refrigerationmass flow rate as well Therefore to reflect the effect of theaforementioned design constraints on the performance of thehybrid cycle from the second lawof the thermodynamic pointof view the results are extended as shown in Figures 11ndash17Theeffects of different climates on the performance of the systemsare compared in different case scenarios as shown in Figures16 and 17



0

2

4

6

8

10

12

14

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)

Figure 12 Exergy destruction rate of PV system during a year

0

50

100

150

200

250

300

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

L (m

)

Figure 13 GSHX minimum required length for each month

0

10

20

30

40

50

60

70

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

A(m

2)

Figure 14 PV panel minimum required area for each month

0

001

002

003

004

005

006

007


Refr

iger

ant m

ass fl

ow ra

te (k

gsminus1)

Figure 15 Heat pump refrigerant mass flow rate variation

00

05

10

15

20

25

30

35

0

50

100

150

200

250

300


Exer

gy d

estr

uctio

n ra

te (k

W)

L (m

)

Isfahan-destruction rate Yazd-destruction rateShahrekord-destruction rate Isfahan-lengthYazd-length Shahrekord-length

Figure 16 Monthly GSHX minimum required length and systemexergy destruction rate

Isfahan-destruction area Yazd-destruction areaShahrekord-destruction area Isfahan-areaYazd-area Shahrekord-area

0

2

4

6

8

10

12

14

16

18

20

0

20

40

60

80

100

120

140


Exer

gy d

estr

uctio

n ra

te (k

W)

A(m

2)

Figure 17 Monthly PV panel minimum required area and systemexergy destruction rate


Figures 11 and 12 present the exergy destruction rate ofGSHP and PV system during a year based on the minimumrequired GSHX length and PV panel area respectively Theexergy destruction rate of the entire cycle can be divided intotwo unavoidable and avoidable parts The unavoidable partrefers to exergy destruction due to irreversibility of differentapplicable process that takes place within the hybrid cyclewith the minimum required sizes of the compartments andthe other part is related to overdesign condition of the systemin different months In other words unavoidable exergydestruction is due to internal irreversibility of componenthowever the avoidable exergy destruction is due to overde-sign of system such as excessive photovoltaic area or GSHXlength An air conditioning system for a specific buildingis usually designed for the extreme climate conditions forexample the hottest and coldest day of a year and controlsystems are considered to minimize energy consumption forthe rest of the year However in case of using solar andgeothermal systems the length of heat exchangers and thearea of PV panels only match with the maximum energydemand and it leads to excess input exergy loss during mostof the days of operation It is observed that exergy loss due toinput and demand exergy mismatch is much higher in thePV system comparing with GSHP system Excess availableenergy can be stored for system operation during either nightor peak hours In fact the design of the entire cycle can beoptimized based on the average energy demand and energystorage systems can be used to compensate for the peakenergy consumption conditions As it is shown in Figures 12and 14 during the hot season a considerable portion of thesolar PV panels is not utilized Maximum exergy destructionrate occurs in May due to mismatch between system sizeand building energy demandsThe cooling and heating loadsat this month are minimum with amount of about 14 kWAlmost 12 kW of destructed exergy at this month is avoidableby energy storage in battery

The variation of heat pump refrigerant flow rate based onthe climate changes during a year is illustrated in Figure 15It can be concluded that for the city of Isfahan duringthe cold months of winter when both PV panelrsquos area andGSHX length are maximum high refrigerant flow rates arealso required In fact high energy demand and low solarirradiation during these months lead to considerable almost2 times increase in irreversibility This irreversibility mostlyoccurs in heat exchangers of the hybrid cycle

441 Effect of Climate Changes on System Performance Inorder to investigate the performance of the hybrid cycle indifferent climates the calculations are repeated for two morecities with different weather conditions The hybrid cycle isdesigned to supply the maximum and heating and coolingloads during a year Isfahan city has warm summers and coldwinters Shahrekord city has quite coldwinters andmild sum-mers and Yazd city has very hot summers and mild wintersGround temperature weather data and solar irradiance forthe three different cities are obtained via local meteorologicaldata Variation of the required length of GSHX during a yearis more uniform for Yazd city but the required PV panel areavaries considerably Figures 16 and 17 compare the exergy

21

44

28

116

155 159

Yazd Shahrekord Isfahan

Area (m2)Length (m)

Figure 18 Average required PV area and GSHX length

destruction rates of the hybrid cycle in the three cities Itcan be concluded that both GSHX and PV systems havethe largest exergy destruction rate in Shahrekord city due toconsiderable changes of the atmosphere average temperatureduring a year and also dimensional mismatch between therequired and available sizes of GSHX and PV The buildingin Shahrekord city has much lower cooling load than heatingload whereas the situation is vice versa in Yazd cityThereforedifferent arrangements to avoid exergy destruction can bemade in these two cities In other words energy storagesystems and control systems may be applied based on thehybrid cycle performance in each city individuallyThe resultsshow that the hybrid cycle has almost two times lower exergydestruction rate during the cold season comparing with thehot season Although the design of GSHX and PV systemsis based on the maximum heating and cooling loads excessabsorbed energy can be saved in battery or prevented using abypass valve in case of ground source heat exchangers

In another approach the hybrid cycle can be designedbased on the average energy demands of the building duringa year Consequently the GSHX and PV sizes are reduced andthe exergy destruction due tomismatch of the system size andenergy demands can be minimized The capital investmentof the system is also reduced considerably Since the hybridcycle in this case cannot supply the energy demands of thebuilding in somemonths the grid electricitymay compensatefor the required loads Figure 18 shows the average solar PVpanel area and GSHX length for 3 different climates that canbe considered for redesigning the cycle however it mightnot be the optimum solution as the exergy efficiency andthe investment cost should be simultaneously optimized ina detailed study

45 Environmental Benefits The hybrid GSHP-PV cyclecan be utilized to supply the total or part of the buildingenergy demand that leads to considerable decreases in CO

2


emissions Based on the cooling and heating energy demandsof the building that is located in Isfahan as shown inFigure 2 the annual energy consumption (AEC) would beapproximately 60000 kWh per year Based on the lowerheating value (LHV = 47174MJkg) of natural gas and 40percent energy conversion efficiency (120578 = 40) in powerplants almost 20000m3 of methane will be saved accordingto (24) Equivalent carbon dioxide emission is calculated by(25) In this equation 119864

119888is specific carbon dioxide emissions

of natural gas Based on (25) (with 119864119888= 02) reduction

of about 12 times 104 kg carbon dioxide emission is achievedannually [22 33] If the hybrid cycle is designed based on theaverage required area and length of PV andGSHX the annualcarbon dioxide emission reduction is almost 085 times 104 kg

forall = 36 (MjkWh) times AEC(120588 times 120578 times LHV)

(24)

119898 = 119864119888times AEC (25)

5 Conclusion

The performance of a hybrid solar-geothermal air condi-tioning system is investigated to provide the cooling andheating energy demands of a residential building Utilizationof green sources of energy results in low exergy efficiency ofabout 10 percent since solar and geothermal energy conver-sion facilities are considerably exergy destructive Howeverconsiderable saving in fossil fuels and reduction in greenhouse effects are observed The hybrid cycle performance indifferent climates is evaluated and it is observed that theexergy destruction due tomismatch of the area of solar panelsand length of ground source heat exchanger with energydemands in each month is less in climates with very hotsummer and mild winter The sustainability index of theground source heat pump systems greatly depends on thedead state temperature whereas the PV system does notAlmost 76 percent of the exergy destruction in the hybridcycle is due to inefficiencies of the PV system and about 70percent of irreversibility in GSHP system occurs in the heatexchangersThe following conclusions aremade in this study

(i) The hybrid systemhas higher exergy efficiency duringthe cold season

(ii) In the hybrid system exergy destruction mostly takesplace in photovoltaic modules

(iii) The photovoltaic cells AC-DC converter and batterysystem destruct about 82 of overall input exergy

(iv) About 76 of PV panel input exergy is destroyed dueto energy conversion deficiencies of the PV panels

(v) Exergy loss due to mismatch of input and demandexergy is much higher in the PV system comparingwith the GSHP system

(vi) In the GSHP system most exergy destruction takesplace in heat exchangers

(vii) Geothermal system has a better performance duringthe cold season because of the highest difference

between ground depth temperature and ambient tem-perature

(viii) The PV system sustainability index is 12 during ayear but the sustainability index of GSHP system isa function of dead state temperature

(ix) The hybrid system ismore sustainable during the coldseason

(x) If the hybrid cycle is designed based on the averageenergy demands of the building during a year theGSHX and PV sizes are reduced and the exergydestruction due to mismatch of the system size andenergy demands can be minimized

(xi) If the cycle is designed based on the average requiredarea and length of PV and GSHX the annual carbondioxide emission reduction is almost 5 times 104 kg

The evaluation of the hybrid system (GSHP coupled with PVpanel) for different cities (with different climates) results inthe following conclusions

(i) Both GSHX and PV systems have the largest exergydestruction rate in Shahrekord city (the coldest cli-mate) due to considerable changes of the atmosphereaverage temperature during a year and also dimen-sional mismatch between the required and availablesizes of GSHX and PV

(ii) Different arrangements to avoid exergy destructioncan be made in Shahrekord and Yazd

Although coupling the GSHX and PV systems causes consid-erable exergy destruction (especially during the cold season)the hybrid system is capable of providing a clean source ofdistrict cooling and heating for regions with limited accessto power grid It is suggested that more study be conductedin order to evaluate primary and secondary cost (exergoe-conomical aspect) The optimum design of the GSHX-PVsystem can be identified using exergoeconomic analysis thatis undertaken as the continuation of this study

Nomenclatures

Variables

119860 Photovoltaic panels area (m2)AEC Annual energy consumption (kWh)1198601015840 Temperature wave magnitude (K)119889 Depth parameter (m)119864 Energy (kJ)119864119888 Specific carbon dioxide emissions

ℎ Enthalpy per unit of mass (kJ kgminus1)119868 Irradiance intensity (kJmminus2) Irreversibility (destruction) rate (kJ sminus1)119868119898 Electrical current (ampere)

119871 Ground heat exchanger length (m)LHV Lower heating value (MJkg)119875 Reference pressure (kPa) Heat transfer rate (kJ)119877 Heat resistance (kJmminus1 sminus1 Kminus1)


119879 Temperature (K)119879 Mean temperature (K)119881119898 Electrical voltage (volt)

Work rate (kJ)119898 Mass (kg) Mass flow rate (kg sminus1)119899 Number of heat exchangers119905 Time (s)1199050 Time of the yearrsquos warmest day (hour)

119881 Velocity (m sminus1)119911 Ground depth (m)forall Volume (m3)

Greek Letters

Φ Exergy (kJ)Ψ Flow exergy (kJ kgminus1)120572 Conductivity of soil (m2 sminus1)120587 Global constantg Gravity acceleration (m sminus2)120595 Flow exergy (kJ kgminus1)120596 Temperature wave frequency (sminus1)

Efficiencies

COP Coefficient of performance120578II Exergy efficiency120578119892119901

Ground pump efficiency120578119892119909

Ground heat exchanger efficiency1205781199011119888

Evaporator efficiency in cooling mode1205781199012119888

Condenser efficiency in cooling mode1205781199011ℎ

Evaporator efficiency in heating mode1205781199012ℎ

Condenser efficiency in heating mode120578119901119901

Refrigerant pump efficiency120578119901V Expansion valve efficiency120578pce Power conversion efficiency120578119904119891 Fan-coil heat exchanger efficiency

120578119904119901 Fan-coil pump efficiency

Subscripts

0 Dead state (reference)CV Control VolumePV Photovoltaic119888 Compressor119889 Design condition119890 Electrical119892 Groundgeo Geothermal119894 Initial conditionin Inletload Cooling and heating loadsmean Averagedout Outlettot Total conditiontr Throttling Process119904 Solar

Operators

119889119889119905 Time derivationsum Summation

Abbreviations

EES Engineering Equation SolverGSHP Ground source heat pumpGSHX Ground source heat exchanger

Competing Interests

The authors declare that they have no competing interests

References

[1] D Urge-Vorsatz L F Cabeza S Serrano C Barreneche and KPetrichenko ldquoHeating and cooling energy trends and drivers inbuildingsrdquo Renewable and Sustainable Energy Reviews vol 41pp 85ndash98 2015

[2] Low Exergy Systems for High-Performance Buildings andCommunities httpwwwannex49infobackgroundhtml

[3] D Schmidt ldquoLow exergy systems for high-performance build-ings and communitiesrdquo Energy and Buildings vol 41 no 3 pp331ndash336 2009

[4] O Kwon K Bae and C Park ldquoCooling characteristics ofground source heat pumpwith heat exchangemethodsrdquoRenew-able Energy vol 71 pp 651ndash657 2014

[5] MDeCarli S Fiorenzato andA Zarrella ldquoPerformance of heatpumpswith direct expansion in vertical groundheat exchangersin heating moderdquo Energy Conversion and Management vol 95pp 120ndash130 2015

[6] W Wu T You B Wang W Shi and X Li ldquoSimulation ofa combined heating cooling and domestic hot water systembased on ground source absorption heat pumprdquoApplied Energyvol 126 pp 113ndash122 2014

[7] M Yari andN Javani ldquoPerformance assessment of a horizontal-coil geothermal heat pumprdquo International Journal of EnergyResearch vol 31 no 3 pp 288ndash299 2007

[8] J Hirvonen G Kayo S Cao A Hasan and K Siren ldquoRenew-able energy production support schemes for residential-scalesolar photovoltaic systems in Nordic conditionsrdquo Energy Policyvol 79 pp 72ndash86 2015

[9] A Martinez-Rubio F Sanz-Adan and J Santamaria ldquoOptimaldesign of photovoltaic energy collectors with mutual shadingfor pre-existing building roofsrdquo Renewable Energy vol 78 pp666ndash678 2015

[10] E K Akpinar and A Hepbasli ldquoA comparative study on exer-getic assessment of two ground-source (geothermal) heat pumpsystems for residential applicationsrdquo Building and Environmentvol 42 no 5 pp 2004ndash2013 2007

[11] Y Bi X Wang Y Liu H Zhang and L Chen ldquoComprehensiveexergy analysis of a ground-source heat pump system for bothbuilding heating and cooling modesrdquo Applied Energy vol 86no 12 pp 2560ndash2565 2009

[12] A Hepbasli and O Akdemir ldquoEnergy and exergy analysisof a ground source (geothermal) heat pump systemrdquo EnergyConversion and Management vol 45 no 5 pp 737ndash753 2004

[13] H Sayyaadi E H Amlashi andMAmidpour ldquoMulti-objectiveoptimization of a vertical ground source heat pump using


evolutionary algorithmrdquo Energy Conversion and Managementvol 50 no 8 pp 2035ndash2046 2009

[14] L C Tagliabue M Maistrello and C Del Pero ldquoSolar heatingand air-conditioning by GSHP coupled to PV system for a costeffective high energy performance buildingrdquo Energy Procediavol 30 pp 683ndash692 2012

[15] M Bakker H A Zondag M J Elswijk K J Strootmanand M J M Jong ldquoPerformance and costs of a roof-sizedPVthermal array combinedwith a ground coupled heat pumprdquoSolar Energy vol 78 no 2 pp 331ndash339 2005

[16] A L Biaou and M A Bernier ldquoAchieving total domestichot water production with renewable energyrdquo Building andEnvironment vol 43 no 4 pp 651ndash660 2008

[17] Q-Y Li Q Chen and X Zhang ldquoPerformance analysis of arooftop wind solar hybrid heat pump system for buildingsrdquoEnergy and Buildings vol 65 pp 75ndash83 2013

[18] M Mikati M Santos and C Armenta ldquoElectric grid depen-dence on the configuration of a small-scale wind and solarpower hybrid systemrdquo Renewable Energy vol 57 pp 587ndash5932013

[19] L Dai S Li L DuanMu X Li Y Shang and M DongldquoExperimental performance analysis of a solar assisted groundsource heat pump system under different heating operationmodesrdquoAppliedThermal Engineering vol 75 pp 325ndash333 2015

[20] E Bertram ldquoSolar assisted heat pump systems with ground heatexchangermdashsimulation studiesrdquo Energy Procedia vol 48 pp505ndash514 2014

[21] A Sahay V K Sethi A C Tiwari and M Pandey ldquoA review ofsolar photovoltaic panel cooling systems with special referenceto Ground coupled central panel cooling system (GC-CPCS)rdquoRenewable and Sustainable Energy Reviews vol 42 pp 306ndash3122015

[22] F Sobhnamayan F Sarhaddi M A Alavi S Farahat and JYazdanpanahi ldquoOptimization of a solar photovoltaic thermal(PVT) water collector based on exergy conceptrdquo RenewableEnergy vol 68 pp 356ndash365 2014

[23] E Saloux A Teyssedou and M Sorin ldquoAnalysis of photo-voltaic (PV) and photovoltaicthermal (PVT) systems usingthe exergy methodrdquo Energy and Buildings vol 67 pp 275ndash2852013

[24] M Gholampour M Ameri and M Sheykh SamanildquoExperimental study of performance of Photovoltaic-ThermalUnglazed Transpired Solar Collectors (PVUTCs) energyexergy and electrical-to-thermal rational approachesrdquo SolarEnergy vol 110 pp 636ndash647 2014

[25] S N Jahromi A Vadiee and M Yaghoubi ldquoExergy andeconomic evaluation of a commercially available PVT collectorfor different climates in Iranrdquo Energy Procedia vol 75 pp 444ndash456 2015

[26] A Bejan Advanced Engineering Thermodynamics John Wileyamp Sons New York NY USA 1988

[27] K Wark Advanced Thermodynamics for Engineers McGraw-Hill New York NY USA 1995

[28] M Boxwell Solar Electricity Handbook A Simple PracticalGuide to Using Electric Solar Panels and Designing and InstallingPhotovoltaic Solar PV Systems Code Green Publishing 2009

[29] HCaliskan IDincer andAHepbasli ldquoEnergy exergy and sus-tainability analyses of hybrid renewable energy based hydrogenand electricity production and storage systems modeling andcase studyrdquoAppliedThermal Engineering vol 61 no 2 pp 784ndash798 2013

[30] S Kalogirou Solar Energy Engineering Processes and SystemsAcademic Press 2009 httpwwwbooks24x7commarcaspbookid=37184

[31] J R S Brownson Solar Energy Conversion Systems 2014 httppubliceblibcomchoicepublicfullrecordaspxp=1562328

[32] C Koroneos and M Tsarouhis ldquoExergy analysis and life cycleassessment of solar heating and cooling systems in the buildingenvironmentrdquo Journal of Cleaner Production vol 32 pp 52ndash602012

[33] CarbonDioxide Emission httpwwwengineeringtoolboxcomco2-emission-fuels-d 1085html

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of



RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



Combination of different renewable energy sources tomeet the demands of a sustainable building is widely studiedLi et al [17] described a rooftop hybrid heat pump systemthat uses wind and solar energy to provide hot water heatingand cooling from energy exergy and environmental pointof view Mikati et al overviewed a small-scale distributedpower system that contains photovoltaic arrays small-scalewind turbines and an electric grid connection [18] Dai etal conducted an experimental study to evaluate the effectof operation modes on the heating performance of a solarassisted ground source heat pump system (SAGSHPS) [19]Moreover different concepts of solar assisted heat pumpsystems with ground heat exchanger are simulated accordingto IEA SHC Task44HPP Annex38 reference conditionsusing TRNSYS softwareThe dependency of system efficiencyon seasonal performance factor and possible shortening ofthe ground heat exchanger by minimum temperature atthe ground heat exchanger inlet are evaluated [20] Theperformance of a new system for cooling of solar PV panelscalled Ground-Coupled Central Panel Cooling System (GC-CPCS) which is in operation at the Energy Park of RajivGandhi Proudyogiki Vishwavidyalaya (RGPV) is studiedby Sahay et al [21] Exergy analysis of photovoltaic systemhas been conducted broadly Sobhnamayan et al [22] haveinvestigated an optimized solar photovoltaic thermal (PVT)water collector based on exergy concept Exergy analyses ofphotovoltaic (PV) and photovoltaicthermal (PVT) systemswere presented by Saloux et al [23] Gholampour et al[24] have evaluated the performance of the PVUTC andUTC systems by introducing energy efficiency as a functionof electrical-to-thermal ratio number and also the secondlaw efficiency Exergy and economic evaluation of thermalphotovoltaic (PVT) water based collectors for differentclimates in Iran have been conducted by Jahromi et al [25]

In this study an exergy analysis is conducted to investigatethe performance of an integrated PV-GSHP system forspace heating and cooling of a remote building A generalarrangement schematic view of the system is illustrated inFigure 1 The required area of SPV panels and GSHP neededlength are calculated for the hybrid air conditioning systemof a 200m2 building in a remote area The effect of differentclimates on system performance is investigated based on themeteorological data of three cities of Iran (Isfahan Yazdand Shahrekord) It is assumed that the building structureis identical for all climate case studies however the coolingand heating loads solar irradiation and ground depth tem-perature are different The analysis is based on the monthlyaveraged energy demands of the building It is assumed thatheat and electricity can be stored during daytime An energyexergy and sustainability analysis is conducted to evaluate thefeasibility of utilizing solar assisted ground source heat pump(GSHP) for air conditioning purposes

2 System Analysis

21 Heating and Cooling Load A remote building with200m2 area located in Isfahan (elevation 1590m) is consid-ered to study the performance of an integrated geothermalheat pump and photovoltaic system that provides heating and

Battery groups

Solar irradiation Photovoltaic panel

N

(electricity storage)Heat pump

unit

Gro

und

sour

ce h

eat e

xcha

nger

Figure 1 Schematic viewof the solar assistedGSHPair conditioningsystem

cooling loads The system performances are compared fordifferent cities of Iran including Yazd (elevation 1216m) andShahrekord (elevation 2061m) Figure 1 shows a schematicview of the residential building and the solar assisted geother-mal heat pumpThe heating cooling and hot water demandsof the building are calculated based on outdoor designconditions of each city on an hourly basis

22 System Description Figure 3 shows a flow diagram of theintegrated solar assisted GSHP system that operates as an off-grid energy system for the specified residential building Itconsists of three main loops

(1) The ground loop delivers heat energy (in coolingmode) to ground sublayers or takes heat energy (inheating mode) from the ground A circulating pumpcirculateswater as aworking fluid in the loop (stream1) Heat is exchanged with the ground via a networkof 119899 number of GSHXs with overall efficiency of 120578

119892119909

The ground temperature 119879119892is almost constant during

a year(2) The primary loop is basically a Rankin refriger-

ation cycle that consists of two heat exchangerswith exchangeable functions depending on coolingor heating season In heating mode the first heatexchanger takes heat from the ground loop as anevaporator while the other heat exchanger deliversheat to the secondary loop as a condenser In coolingmode the first heat exchanger delivers heat to theground loop as a condenser and the other extractsheat from the secondary loop as an evaporatorA compressor pressurizes refrigerant R-134a in theprimary loop A 4-way valve is adopted to switch











and 1198750= 101325 kPa





119889

119889119905(119872CV) = sum

in minussum

out

119889

119889119905(119864CV) = + +sum

inℎ minussum

outℎ

119889

119889119905(ΦCV) = [sum

119894(1 minus

1198790

119879119894

)] + [ + 1198750

119889

119889119905(forallCV)]


out120595 minus CV

(1)



1198812

2+ g119911 (2)





119879119889

) (3)










minus5

0

5

10

15

20

25

30

35

40

45

50




Tem

pera

ture

(∘C)

(a)

0

5

10

15

20


Load

s (kW

)



(b)




out120595 (7)




tr = (120595in minus 120595out) (9)



119879geo) (10)




0) minus

119911

119889) times 119890minus119911119889

(11)





119871GSHX =geo

119879geo minus 119879119882119866

1

119877tot (12)








solar = 119860119868119904 (14)


panel net area


1

2

3



4

Compressor

g1

g2

g3

r1

r2

r3r4

h3

h2

h1


Ground loop pump

GSHX

Expansion valve

Secondary loop pump



4-wayvalve

Con

vert

or an

d co

ntro

ller

Solar PV panel





3(1198790

119879119904

) +1

3(1198790

119879119904

)

4

) 119868119904119860 (15)





PV = 119881119898119868119898 (17)




120578pce =119881119898119868119898

119868119904119860 (18)


120578II =Φload

Φgeo + ΦPV (19)


0

1

2

3

4

5

6

7

8



Mon

thly

aver

age i

rrad

iatio

n (k

Wh

m2

dayminus

1)






SI = 1

1 minus Ψ (21)

where


(22)




RI =119904

tot (23)







54

6

8

1

2

7

3










0

1

2

3

4

5

6

7

8

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

120578II

()



1

11

12

13

14

15

16

17

18

0 5 10 15 20

SI


SI_PVSI_GSHP




1

105

11

115

12

125

13

135

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

SI

SI_PVSI_GSHX


PV (76)

PCE (6)GSHX (2)


Compressor (3)

Throttling (1

)




Throttling (6)

GSHX (10

)




0

05

1

15

2

25

3

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)







0

2

4

6

8

10

12

14

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)


0

50

100

150

200

250

300

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

L (m

)


0

10

20

30

40

50

60

70

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

A(m

2)


0

001

002

003

004

005

006

007


Refr

iger

ant m

ass fl

ow ra

te (k

gsminus1)


00

05

10

15

20

25

30

35

0

50

100

150

200

250

300


Exer

gy d

estr

uctio

n ra

te (k

W)

L (m

)




0

2

4

6

8

10

12

14

16

18

20

0

20

40

60

80

100

120

140


Exer

gy d

estr

uctio

n ra

te (k

W)

A(m

2)






21

44

28

116

155 159


Area (m2)Length (m)





2







(24)

119898 = 119864119888times AEC (25)

5 Conclusion


















Nomenclatures

Variables








Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation



















and 1198750= 101325 kPa





119889

119889119905(119872CV) = sum

in minussum

out

119889

119889119905(119864CV) = + +sum

inℎ minussum

outℎ

119889

119889119905(ΦCV) = [sum

119894(1 minus

1198790

119879119894

)] + [ + 1198750

119889

119889119905(forallCV)]


out120595 minus CV

(1)



1198812

2+ g119911 (2)





119879119889

) (3)










minus5

0

5

10

15

20

25

30

35

40

45

50




Tem

pera

ture

(∘C)

(a)

0

5

10

15

20


Load

s (kW

)



(b)




out120595 (7)




tr = (120595in minus 120595out) (9)



119879geo) (10)




0) minus

119911

119889) times 119890minus119911119889

(11)





119871GSHX =geo

119879geo minus 119879119882119866

1

119877tot (12)








solar = 119860119868119904 (14)


panel net area


1

2

3



4

Compressor

g1

g2

g3

r1

r2

r3r4

h3

h2

h1


Ground loop pump

GSHX

Expansion valve

Secondary loop pump



4-wayvalve

Con

vert

or an

d co

ntro

ller

Solar PV panel





3(1198790

119879119904

) +1

3(1198790

119879119904

)

4

) 119868119904119860 (15)





PV = 119881119898119868119898 (17)




120578pce =119881119898119868119898

119868119904119860 (18)


120578II =Φload

Φgeo + ΦPV (19)


0

1

2

3

4

5

6

7

8



Mon

thly

aver

age i

rrad

iatio

n (k

Wh

m2

dayminus

1)






SI = 1

1 minus Ψ (21)

where


(22)




RI =119904

tot (23)







54

6

8

1

2

7

3










0

1

2

3

4

5

6

7

8

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

120578II

()



1

11

12

13

14

15

16

17

18

0 5 10 15 20

SI


SI_PVSI_GSHP




1

105

11

115

12

125

13

135

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

SI

SI_PVSI_GSHX


PV (76)

PCE (6)GSHX (2)


Compressor (3)

Throttling (1

)




Throttling (6)

GSHX (10

)




0

05

1

15

2

25

3

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)







0

2

4

6

8

10

12

14

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)


0

50

100

150

200

250

300

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

L (m

)


0

10

20

30

40

50

60

70

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

A(m

2)


0

001

002

003

004

005

006

007


Refr

iger

ant m

ass fl

ow ra

te (k

gsminus1)


00

05

10

15

20

25

30

35

0

50

100

150

200

250

300


Exer

gy d

estr

uctio

n ra

te (k

W)

L (m

)




0

2

4

6

8

10

12

14

16

18

20

0

20

40

60

80

100

120

140


Exer

gy d

estr

uctio

n ra

te (k

W)

A(m

2)






21

44

28

116

155 159


Area (m2)Length (m)





2







(24)

119898 = 119864119888times AEC (25)

5 Conclusion


















Nomenclatures

Variables








Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










minus5

0

5

10

15

20

25

30

35

40

45

50




Tem

pera

ture

(∘C)

(a)

0

5

10

15

20


Load

s (kW

)



(b)




out120595 (7)




tr = (120595in minus 120595out) (9)



119879geo) (10)




0) minus

119911

119889) times 119890minus119911119889

(11)





119871GSHX =geo

119879geo minus 119879119882119866

1

119877tot (12)








solar = 119860119868119904 (14)


panel net area


1

2

3



4

Compressor

g1

g2

g3

r1

r2

r3r4

h3

h2

h1


Ground loop pump

GSHX

Expansion valve

Secondary loop pump



4-wayvalve

Con

vert

or an

d co

ntro

ller

Solar PV panel





3(1198790

119879119904

) +1

3(1198790

119879119904

)

4

) 119868119904119860 (15)





PV = 119881119898119868119898 (17)




120578pce =119881119898119868119898

119868119904119860 (18)


120578II =Φload

Φgeo + ΦPV (19)


0

1

2

3

4

5

6

7

8



Mon

thly

aver

age i

rrad

iatio

n (k

Wh

m2

dayminus

1)






SI = 1

1 minus Ψ (21)

where


(22)




RI =119904

tot (23)







54

6

8

1

2

7

3










0

1

2

3

4

5

6

7

8

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

120578II

()



1

11

12

13

14

15

16

17

18

0 5 10 15 20

SI


SI_PVSI_GSHP




1

105

11

115

12

125

13

135

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

SI

SI_PVSI_GSHX


PV (76)

PCE (6)GSHX (2)


Compressor (3)

Throttling (1

)




Throttling (6)

GSHX (10

)




0

05

1

15

2

25

3

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)







0

2

4

6

8

10

12

14

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)


0

50

100

150

200

250

300

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

L (m

)


0

10

20

30

40

50

60

70

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

A(m

2)


0

001

002

003

004

005

006

007


Refr

iger

ant m

ass fl

ow ra

te (k

gsminus1)


00

05

10

15

20

25

30

35

0

50

100

150

200

250

300


Exer

gy d

estr

uctio

n ra

te (k

W)

L (m

)




0

2

4

6

8

10

12

14

16

18

20

0

20

40

60

80

100

120

140


Exer

gy d

estr

uctio

n ra

te (k

W)

A(m

2)






21

44

28

116

155 159


Area (m2)Length (m)





2







(24)

119898 = 119864119888times AEC (25)

5 Conclusion


















Nomenclatures

Variables








Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










1

2

3



4

Compressor

g1

g2

g3

r1

r2

r3r4

h3

h2

h1


Ground loop pump

GSHX

Expansion valve

Secondary loop pump



4-wayvalve

Con

vert

or an

d co

ntro

ller

Solar PV panel





3(1198790

119879119904

) +1

3(1198790

119879119904

)

4

) 119868119904119860 (15)





PV = 119881119898119868119898 (17)




120578pce =119881119898119868119898

119868119904119860 (18)


120578II =Φload

Φgeo + ΦPV (19)


0

1

2

3

4

5

6

7

8



Mon

thly

aver

age i

rrad

iatio

n (k

Wh

m2

dayminus

1)






SI = 1

1 minus Ψ (21)

where


(22)




RI =119904

tot (23)







54

6

8

1

2

7

3










0

1

2

3

4

5

6

7

8

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

120578II

()



1

11

12

13

14

15

16

17

18

0 5 10 15 20

SI


SI_PVSI_GSHP




1

105

11

115

12

125

13

135

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

SI

SI_PVSI_GSHX


PV (76)

PCE (6)GSHX (2)


Compressor (3)

Throttling (1

)




Throttling (6)

GSHX (10

)




0

05

1

15

2

25

3

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)







0

2

4

6

8

10

12

14

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)


0

50

100

150

200

250

300

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

L (m

)


0

10

20

30

40

50

60

70

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

A(m

2)


0

001

002

003

004

005

006

007


Refr

iger

ant m

ass fl

ow ra

te (k

gsminus1)


00

05

10

15

20

25

30

35

0

50

100

150

200

250

300


Exer

gy d

estr

uctio

n ra

te (k

W)

L (m

)




0

2

4

6

8

10

12

14

16

18

20

0

20

40

60

80

100

120

140


Exer

gy d

estr

uctio

n ra

te (k

W)

A(m

2)






21

44

28

116

155 159


Area (m2)Length (m)





2







(24)

119898 = 119864119888times AEC (25)

5 Conclusion


















Nomenclatures

Variables








Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0

1

2

3

4

5

6

7

8



Mon

thly

aver

age i

rrad

iatio

n (k

Wh

m2

dayminus

1)






SI = 1

1 minus Ψ (21)

where


(22)




RI =119904

tot (23)







54

6

8

1

2

7

3










0

1

2

3

4

5

6

7

8

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

120578II

()



1

11

12

13

14

15

16

17

18

0 5 10 15 20

SI


SI_PVSI_GSHP




1

105

11

115

12

125

13

135

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

SI

SI_PVSI_GSHX


PV (76)

PCE (6)GSHX (2)


Compressor (3)

Throttling (1

)




Throttling (6)

GSHX (10

)




0

05

1

15

2

25

3

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)







0

2

4

6

8

10

12

14

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)


0

50

100

150

200

250

300

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

L (m

)


0

10

20

30

40

50

60

70

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

A(m

2)


0

001

002

003

004

005

006

007


Refr

iger

ant m

ass fl

ow ra

te (k

gsminus1)


00

05

10

15

20

25

30

35

0

50

100

150

200

250

300


Exer

gy d

estr

uctio

n ra

te (k

W)

L (m

)




0

2

4

6

8

10

12

14

16

18

20

0

20

40

60

80

100

120

140


Exer

gy d

estr

uctio

n ra

te (k

W)

A(m

2)






21

44

28

116

155 159


Area (m2)Length (m)





2







(24)

119898 = 119864119888times AEC (25)

5 Conclusion


















Nomenclatures

Variables








Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










54

6

8

1

2

7

3










0

1

2

3

4

5

6

7

8

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

120578II

()



1

11

12

13

14

15

16

17

18

0 5 10 15 20

SI


SI_PVSI_GSHP




1

105

11

115

12

125

13

135

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

SI

SI_PVSI_GSHX


PV (76)

PCE (6)GSHX (2)


Compressor (3)

Throttling (1

)




Throttling (6)

GSHX (10

)




0

05

1

15

2

25

3

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)







0

2

4

6

8

10

12

14

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)


0

50

100

150

200

250

300

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

L (m

)


0

10

20

30

40

50

60

70

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

A(m

2)


0

001

002

003

004

005

006

007


Refr

iger

ant m

ass fl

ow ra

te (k

gsminus1)


00

05

10

15

20

25

30

35

0

50

100

150

200

250

300


Exer

gy d

estr

uctio

n ra

te (k

W)

L (m

)




0

2

4

6

8

10

12

14

16

18

20

0

20

40

60

80

100

120

140


Exer

gy d

estr

uctio

n ra

te (k

W)

A(m

2)






21

44

28

116

155 159


Area (m2)Length (m)





2







(24)

119898 = 119864119888times AEC (25)

5 Conclusion


















Nomenclatures

Variables








Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










1

105

11

115

12

125

13

135

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

SI

SI_PVSI_GSHX


PV (76)

PCE (6)GSHX (2)


Compressor (3)

Throttling (1

)




Throttling (6)

GSHX (10

)




0

05

1

15

2

25

3

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)







0

2

4

6

8

10

12

14

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)


0

50

100

150

200

250

300

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

L (m

)


0

10

20

30

40

50

60

70

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

A(m

2)


0

001

002

003

004

005

006

007


Refr

iger

ant m

ass fl

ow ra

te (k

gsminus1)


00

05

10

15

20

25

30

35

0

50

100

150

200

250

300


Exer

gy d

estr

uctio

n ra

te (k

W)

L (m

)




0

2

4

6

8

10

12

14

16

18

20

0

20

40

60

80

100

120

140


Exer

gy d

estr

uctio

n ra

te (k

W)

A(m

2)






21

44

28

116

155 159


Area (m2)Length (m)





2







(24)

119898 = 119864119888times AEC (25)

5 Conclusion


















Nomenclatures

Variables








Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











0

2

4

6

8

10

12

14

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

Exer

gy d

estr

uctio

n (k

W)


0

50

100

150

200

250

300

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

L (m

)


0

10

20

30

40

50

60

70

Jan

Feb

Mar

Apr

May Jun Jul

Aug

Sep

Oct

Nov Dec

A(m

2)


0

001

002

003

004

005

006

007


Refr

iger

ant m

ass fl

ow ra

te (k

gsminus1)


00

05

10

15

20

25

30

35

0

50

100

150

200

250

300


Exer

gy d

estr

uctio

n ra

te (k

W)

L (m

)




0

2

4

6

8

10

12

14

16

18

20

0

20

40

60

80

100

120

140


Exer

gy d

estr

uctio

n ra

te (k

W)

A(m

2)






21

44

28

116

155 159


Area (m2)Length (m)





2







(24)

119898 = 119864119888times AEC (25)

5 Conclusion


















Nomenclatures

Variables








Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation













21

44

28

116

155 159


Area (m2)Length (m)





2







(24)

119898 = 119864119888times AEC (25)

5 Conclusion


















Nomenclatures

Variables








Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation















(24)

119898 = 119864119888times AEC (25)

5 Conclusion


















Nomenclatures

Variables








Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation













Greek Letters


Efficiencies










Subscripts


Operators


Abbreviations


Competing Interests


References






































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









Documents

Research Article Performance Assessment of a …downloads.hindawi.com/journals/ijce/2016/5710560.pdfCV = in out, CV = + + in out , CV = 0 1 + + 0 CV + in out CV, whereexergyofanystream