research article characterization of air-based...

Hindawi Publishing CorporationInternational Journal of PhotoenergyVolume 2013 Article ID 978234 10 pageshttpdxdoiorg1011552013978234

Research ArticleCharacterization of Air-Based Photovoltaic Thermal Panels withBifacial Solar Cells

P Ooshaksaraei12 K Sopian1 R Zulkifli2 and Saleem H Zaidi1

1 Solar Energy Research Institute Universiti Kebangsaan Malaysia (UKM) Bangi 43600 Selangor Malaysia2 Department of Mechanical and Materials Engineering Faculty of Engineering and Built EnvironmentUniversiti Kebangsaan Malaysia (UKM) Bangi 43600 Selangor Malaysia

Correspondence should be addressed to P Ooshaksaraei pooryaengukmmy

Received 15 July 2013 Accepted 5 November 2013

Academic Editor Vincenzo Augugliaro

Copyright copy 2013 P Ooshaksaraei et alThis is an open access article distributed under the Creative CommonsAttribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Photovoltaic (PV) panels account for a majority of the cost of photovoltaic thermal (PVT) panels Bifacial silicon solar panels areattractive for PVT panels because of their potential to enhance electrical power generation from the same silicon wafer comparedwith conventional monofacial solar panels This paper examines the performance of air-based bifacial PVT panels with regard tothe first and second laws of thermodynamics Four air-based bifacial PVT panels were designedThe maximum efficiencies of 45to 63were observed for the double-path-parallel bifacial PVT panel based on the first law of thermodynamics Single-path bifacialPVT panel represents the highest exergy efficiency (10) Double-path-parallel bifacial PVT panel is the second preferred designas it generates up to 20 additional total energy compared with the single-path panel However the daily average exergy efficiencyof a double-path-parallel panel is 035 lower than that of a single-path panel

1 Introduction

Solar energy is one of the most environment friendly sourcesof renewable energies that can be utilized in thermal andelectrical applications Photovoltaic thermal (PVT) collec-tors are especially designed to generate both electrical andthermal energies simultaneously Solar air-heater panels alsoreferred to as hybrid panels have been widely studied in thelast decade and have been found to be strongly suitable forapplications that require both electrical and thermal energiessuch as space heating and drying

A PVT panel generally consists of PV cells an absorberplate and a heat removal system In a bifacial PVT panelmonofacial PV cells are replaced by bifacial PV cells and theabsorber plate is replaced by a reflector Reducing the numberof solar cells will significantly reduce the cost of the modulegiven that solar cells are expensive [1]

11 Bifacial Solar Cells Recent studies on PV solar cells havedeveloped the bifacial PV solar cell [2] The bifacial solarcell in contrast with monofacial solar cell has the capabilityto absorb solar radiation from the rear surface as well

as the front surface simultaneously Figure 1 compares themechanism of solar radiation absorption between a bifacialsolar cell and a monofacial solar cell

Solar radiation absorption by the rear surface increaseselectrical energy generation [3] A bifacial PV panel gen-erates 30 to 90 additional electrical energy comparedwith a monofacial PV panel at optimum adjustment [4 5]Industrialized bifacial solar cells have front and rear effi-ciencies of 166 and 128 respectively Assuming identicalmicrostructures on the front and rear surfaces of solar cellsthe lower energy conversion efficiency of the rear surfacecompared with the front surface may be due to differentoptical responses of the front and rear surfaces [6 7]Electrical energy generated by the rear surface of bifacialsolar cells strongly depends on reflection performance of thereflector [8]

12 Reflector Bifacial solar cells increase electrical efficiencyof flat-plate PV panels at negligible cost increase [9] Addi-tional electrical energy generated by the rear surface ofbifacial panels strongly depends on reflection properties and

2 International Journal of Photoenergy

Solar radiation

Solar radiation

Reflector

Monofacial solar cell

Front surface

Back contact

(a)

Bifacial solar cell

Rear surface

Solar radiation

Solar radiation

Reflector

Front surface

(b)

Figure 1 Radiation absorptions of monofacial and bifacial PV solar cells

installation attitude of the reflector Three key parametershave significant effects on panel performance panel slopereflector slope and reflection efficiency However bifacialsolar panels are effective without a reflector in certainapplications [10ndash14] In general solar panels are classifiedeither as one-sun (1X) panel or concentrator panel (multi-X) For bifacial panels the definition of 1X panel and multi-X panel may overlap The front surface of a bifacial cellreceives 1X solar radiation whereas the rear surface mayreceive additional 1X beam radiation [15] Reflection propertyof the reflector depends on surface roughness and colorA wide range of reflectors including diffuse mirror andsemitransparent have been studied [1 10 11 16] Uematsu[1] developed a flat plate bifacial panel by adding a static V-groove concentrator to provide 1X solar radiation on the rearsurface of the bifacial cell which resulted in 856 powerenhancement

Intensity of solar radiation on the rear surface affectsthe power generated by a bifacial PV panel [8] Moehleckeet al [5] studied the reflection properties of painted reflectorsplaced beneath the bifacial solar cells They observed upto 25 enhancement in solar absorption compared withconventional monofacial panels White-colored reflector isthe optimum painted reflector with 75 average reflectanceYellow is the second best color for reflectors followed byorange red green blue brown purple grey dark blue anddark green colors which give 61 to 32 reflection [5]

13 Residential Applications of Bifacial Solar Cells Building-integrated applications of monofacial PV and PVT pan-els have been widely studied whereas the performance ofbuilding-integrated bifacial solar panels has not Bifacial PVpanels could be integrated into residential and commercialbuildings as window-integrated wall-integrated or parkinglot-integrated panels [9]

Bifacial solar cells partially cover the panel area In wall-integrated application the panel is installed with an offsetdistance from the wall Front surface of bifacial solar cellsabsorb a portion of solar radiation whereas a portion ofsolar radiation penetrates through transparent vacant space

between cells the wall reflects light back to the rear surfaceof bifacial cells [16]

Window-integrated bifacial PV panels produce electricalenergy while permitting penetration of faint solar radiationinto the interior area for lighting of residential or commercialbuildings [9 17] Packing factor of solar panel has significantimpact on the amount of solar radiation that penetratesthe PV module [18] Space heating and drying applicationscould also be considered depending on the climate of theinstallation site

14 Air-Based PVT Panel Air-based PVT collectors areuseful for both industrial and residential applications suchas drying and space heating Air-based panel designs areclassified according to the number or glazing and air-pathSingle-glazing double-path (monofacial) panels have higherelectrical and thermal efficiencies compared with single-pathpanel types [19] In an air-based PVT panel PV cells areplaced at the top of the absorber plate and absorb a portion ofsolar radiation that reaches the front surface The remainingportion of solar radiation penetrates the PV cells and reachesthe absorber plate where it is converted into thermal energy

Substituting monofacial PV cells with bifacial PV cellshas led to the development of bifacial PVT panels A bifacialPVT panel equipped with aluminum reflector generates 40additional electrical and thermal energies [20]

Most of the existing PVT panel designs are inappropriatefor bifacial solar cells because the absorber plate covers therear surface of bifacial solar cells [21ndash24] Absence of solarradiation on the rear surface of bifacial solar cells misses thebenefit of dual surface solar radiation absorption of bifacialsolar cells Panel modification is essential the absorber plateshould be substituted by a reflector to reflect back solarradiation to the rear surface of bifacial solar cells

The current research aims to develop new designs ofair-based PVT panels based on bifacial solar cells and toevaluate the performance of the panel with regard to the firstand second laws of thermodynamics This paper representssteady-state simulation and daily simulation based on theclimate of Malaysia

International Journal of Photoenergy 3

Bifacial PV cell Lamination

Air flow

Insulation Reflector(a)

Bifacial PV cell LaminationAir flow 1

Air flow 2

Glass

Insulation Reflector

(b)


Air flow 2

Glass


(c)


Air flow 2

Glass


(d)

Figure 2 Cross-section view of bifacial PVT panel (a) Model 1 (b) Model 2 (c) Model 3 and (d) Model 4

2 Mathematical Modeling

Electrical and thermal performances of PVT panel stronglydepend on cell temperature air flow rate and packing factorof the solar panel Energy balancemethod and exergymethodare the two most well-known methods for performanceevaluation of PVT panels The former (energy balancemethod) is based on the first lawof thermodynamics whereasthe latter (exergy method) is based on the second law ofthermodynamics

21 PVT Panel Design Varieties of air-based PVT panelshave been widely studied in the last decade Most PVT paneldesigns are incorporated with an opaque absorber plate onwhich PV cells are pasted A few monofacial PV and PVTpanel designs have the potential to be developed into a bifacialPVT panel [25 26] Kamthania et al [25] proposed andtested PV cells installed with a separation from the absorberplate and consequently found lower PV cell temperature andadditional electrical energy generation This design has thepotential to be developed into a bifacial PVT solar panel

In a bifacial PVT panel the absorber plate should besubstituted by an appropriate reflector installed beneath thebifacial PV cell to provide solar radiation on the rear surfaceof bifacial solar cells The reflector is the key component of abifacial PV panel Both mirror-type and diffuse-type reflec-tors are suitable for bifacial panel design Figure 2 representsfour air-based bifacial PVT panels developed based on theexisting monofacial PVT panel designs and the requirementsof bifacial solar cells

Configurations of four bifacial PVT panels are describedas follows

Model 1 Single-path air-based bifacial PVT panel witha reflector placed beneath the PV lamination Air flowsbetween the lamination and the reflector (Figure 2(a))

Model 2 Double-path air-based PVT panel with additionallayer of glazing above the PV lamination Two parallel airstreams exist One air channel is above the PV laminationand the other is beneath the lamination (Figure 2(b))The twochannels have similar geometries Each channel carries 50of flow rate


Model 3 This model has a similar configuration to Model2 except that air in the lower channel flows in the directionopposite the upper channel (Figure 2(c))

Model 4 This panel was developed based on Model 3 Theupper and lower channels are in a series Air flows above thePV lamination and flows back through the channel beneaththe lamination (Figure 2(d))

22 Energy Balance Method All four models were simulatedbased on the first law of thermodynamics The followingassumptions were made

(i) Both surfaces of the PV cell have the same electricalefficiencies

(ii) The reflector has 70 reflection efficiency(iii) Natural convection is suppressed inside the panel(iv) The only temperature gradient is along the panel(v) Thermal losses through insulation are negligible

(vi) Ambient airspeed is equal to 1m sminus1

Energy balance equations were developed and solvedfor all models Output energy of the PVT panel consists ofelectrical and thermal parts and efficiency of the panel is acombination of thermal and electrical efficiencies

221 Heat Transfer Coefficients Free convection heat trans-fer coefficients in ambient condition can be obtained fromDuffie and Beckman [27]

ℎ119888

= 28 + 119906Air (1)

where 119906Air is the air velocity over the panel which wasassumed to be 1m sminus1

Internal forced convection heat transfer coefficients isdefined as [28]

ℎ119888

=119870Air119863119867

119873119906 (2)

where ℎ119888

can be determined from Tan and Charters [29]which has been used by Shahsavar and Ameri [30]

ℎ119888

= 00182Re08Pr04 [1 + 1198781015840119863119867119871] (3)

where

1198781015840

= 143 log( 119871

119863119867

) minus 79 for 0 lt (119871

119863119867

) le 60

= 175 for 60 lt (119871

119863119867

)

(4)

Re =120588119906119863

120583

Pr = 07

(5)

222 Evaluation of Performance The total efficiency of thePVT panel is a function of electrical and thermal efficacies

Both surfaces of the bifacial PV cell contribute to elec-trical energy generation where the total electrical energygenerated by bifacial PV cell is defined as follows

ElPV = ElPVfront+ ElPVrear

(6)

The actual electrical efficiency of the PV cell variesaccording to its temperature as [31]

120578PVfront= 120578PVrear

= 120578ref lfloor1 minus Φref (119879Cell minus 119879ref)rfloor (7)

where 119879ref = 25∘C Φref = 1(119879PV minus 119879ref) and 120578ref is the

electrical efficiency of the panel at reference temperature[19 32]

The thermal efficiency of a PVT panel is defined as theratio of thermal energy transferred to working fluid(s) overtotal solar radiation reaching the collector area

120578Th =119862119901

(119879119900

minus 119879119894

)

119878 times 119860 (8)

Electrical energy has a higher value compared withthermal energy which should be considered in calculatingtotal efficiency [30] The total energy efficiency of PVT panelis defined as

120578Total = 120578Th +120578El

120578Power Plant (9)

where 120578Power Plant = 038 is the efficiency of conventionalpower plant [33]

23 Exergy Analysis Method Aforementioned studies eval-uated the panels based on the first law of thermodynamicsHowever exergy method evaluates panels based on the sec-ond law of thermodynamics In exergy method environmenttemperature is the reference temperature in calculating thetheoretical maximum work done by the system in order toreach equilibrium with the reference environment [34]

Increasing the number of glazing is an advantage in PVTpanel Glazing reduces thermal losses and increases thermalefficiency which is an advantage according to the first law ofthermodynamics However solar radiation reflected back bythe cover glass reduces solar radiation to solar cells therebydecreasing electrical energy generation Electrical energy hasa higher value compared with thermal energy according tothe first law of thermodynamics [35]

In accordance with the second law of thermodynamicshigh-value electrical energy loss from reflected light causedby additional glazing should be compared with thermalenergy saved from additional glazing

In PVT panels the maximum output exergy is observedat an inlet fluid temperature of 35∘C whereas the maximumoutput energy is observed at an inlet fluid temperature of31∘C [36] Energy and exergy efficiency rates of PVT panelvary indifferent designs Table 1 presents energy and exergyefficiencies observed in previous studies

The total output exergy of the PVT panel is higher thanthat of PV panel and the thermal energy output of a PVT


Tota

l effi

cien

cy (

)90

80

70

60

50

40

30

20

10

002 004 006 008 01 012 014

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Packing factor = 1

(a)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)

90

80

70

60

50

40

30

20

10

Packing factor = 07

002 004 006 008 01 012 014

(b)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)

90

80

70

60

50

40

30

20

10

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)90

80

70

60

50

40

30

20

10

Packing factor = 03

002 004 006 008 01 012 014

(d)

Figure 3 Total efficiencies of the four models at different packing factors

Table 1 Comparison of energy and exergy efficiencies

Panel type Energy efficiency Exergy efficiencyUnglazed PVT-air [36] 45 1075Single glazed PVT-air [37] 55 135Single glazed PVT-air [38] 55ndash66 12ndash15Double glazed T-air [39] mdash 74PVT-air [40] 33ndash45 113ndash16PVT-water [41] mdash 3ndash15PVT photovoltaic thermal T thermal

panel is significantly higher than its electrical energy output[42] However from the perspective of the second law of

thermodynamics thermal energy has a lower value comparedwith electrical energy

Output exergy of a PVT panel is the sum of electrical andthermal exergies [43]

ExOut = ExEl + ExTh (10)

Electrical energy could be efficiently converted to workThus electrical exergy is assumed to be equal to electricalenergy [35]

ExEl = EnEl

EnEl = EnPV = 120578PV times 119860PV times 119875 times 119878(11)


Thermal exergy is defined as [44]

ExTh = 119862119901

[1198792

minus 1198791

minus 119879119886

(ln 11987921198791

+120574 minus 1

120574ln 11987511198752

)] (12)

where 119879119886

denotes ambient temperature and 1198791

1198792

1198751

and 1198752

are the temperatures and pressures at the inlet and outlet ofthe PVT panel respectively

Exergy of solar radiation reaching the PVT panel isdefined as [45]

ExSun = 119878 [1 minus4

3(119879119886

119879sun) +

1

3(119879119886

119879sun)

4

] (13)

Exergy efficiency is defined as the output exergy (the sumof electrical and thermal output exergies) over the exergy ofsolar radiation [36 44 46 47]

120578Ex =ExOutExSun

(14)

3 Results and Discussion

The mathematical model used in simulating the four panelsat steady-state and daily climate of Malaysia is based on thefirst and second laws of thermodynamics

31 Steady-State First Law of Thermodynamics (Energy Bal-ance Method) The total efficiency of each of the four modelpanels was calculated using (1) to (9) as shown in Figure 3Additional glazing of Models 2 3 and 4 reduces thermal lossand increases total efficiency The effect of additional glazingis advantageous according to the first law of thermodynamics

Increasing the air flow rate leads to increase of internalforced convection heat transfer coefficients according to(2) The higher heat transfer coefficient results in higherheat extraction rate higher thermal efficiency and lowerpanel operation temperatureThe lower PVT panel operationtemperature results in higher PV panel electrical efficiency(see (7)) The total efficiency of the panel is a function ofthermal and electrical efficiencies (see (9)) which is expectedto increase by increasing the air flow rate as observed inFigure 3 The total efficiency of Model 4 was higher thanthat of Model 1 because it has a larger heat transfer surfaceThis finding is similar to the findings of earlier studies [19]Model 2 has higher total efficiency rating thanModel 4 whichcan be attributed to the lower temperature of air enteringthe channel beneath the PV lamination Thermal efficiencyincreases with increasing air mass flow rate because of theincrease in heat transfer coefficient as reported by otherresearchers [30 48 49]

32 Steady-State Second Law of Thermodynamics (ExergyMethod) Steady-state exergy was computed using (10) to(14) The exergy output of a PVT panel is the sum of thermaland electrical exergies (see (10)) [43] The electrical exergy ofa PVT panel is equal to its electrical energy as confirmed by(11) Figure 4 shows the electrical exergy of the four modelswith a packing factor of 07 All four models showed the sametrend as Figure 4 for the packing factors 03 05 and 1

Model 2Model 3

Model 4Model 1

Elec

tric

al ex

ergy

effici

ency

()

84

83

82

81

8

79

78

Total air flow rate (kgs)

Packing factor = 07

002 004 006 008 01 012 014

Figure 4 Electrical exergy of the four panel designs

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Ther

mal

exer

gy effi

cien

cy (

)06

05

04

03

02

01

0

Packing factor = 07

002 004 006 008 01 012 014

Figure 5 Thermal exergy efficiency of the four panel designs

Models 2 3 and 4 showed lower electrical exergiescompared with Model 1 because of the reflection caused byadditional glazing Moreover the white reflector only had70 reflection performance which affected the electricalexergy output of the rear surface of bifacial cells in all fourmodels Electrical exergy efficiency increases by increasingthe air flow rate (Figure 4) which is attributed to higher heatextraction rate lower PV panel temperature and higher PVpanel electrical efficiency consequently (see (7)) Model 1 isthe most simple panel design among four models whichshows the best performance in terms of electrical outputexergy

Thermal exergy of all four models was calculated using(see (12)) as shown in Figure 5 All four models showed thesame trend as Figure 5 for the packing factors 03 05 07 and1


Tota

l exe

rgy

effici

ency

()

102

101

10

99

98

97

96

Flow rate (kgs)

Model 2Model 3Model 4

Model 1

Packing factor = 1

002 004 006 008 01 012 014

(a)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

86

85

84

83

82

81

8

Packing factor = 07

002 004 006 008 01 012 014

(b)

Tota

l exe

rgy

effici

ency

()

69

68

68

67

67

66

66

65

65

64

Flow rate (kgs)


Model 1

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

45

45

44

44

43

43

42

Packing factor = 03

002 004 006 008 01 012 014

(d)

Figure 6 Total exergy efficiencies of the four models at different packing factors

Increasing the air flow rate from 003 kgs to 014 kgs didnot significantly affect electrical exergy as shown in Figure 4However according to Figure 5 a low flow rate is preferred inthe case of all four models

This observation is in accordance with the second lawof thermodynamics and indicates that panels operate at lowtemperature that reduces the quality of output thermal power(exergy) with respect to the second law of thermodynamics(12) Models 2 3 and 4 demonstrated higher thermal exergyat lower air flow rate which has also been observed inearlier studies [25] All four models show the same trendfor thermal output exergy (Figure 5) Output exergy droppedwith increasing air flow rate

The exergy output of a PVT panel is the sum of thermaland electrical exergies (see (10)) [43] Model 1 had a total

exergy efficiency of 448 to 1015 whereas its energyefficiency was 38 to 53 for packing factors 03 to 1 Energyoutput of each of the four models increased with the air flowrate (Figure 3) However the total exergy output of all fourpanels drops by increasing the air flow rate The effect of airflow rate increase from 003 kgs to 014 kgs is less that 1Electrical output exergy of the PVT panel is the dominantoutput exergy which is not much depended on air flow rate(Figure 4)

Models 2 3 and 4 had additional glazing that improvedtheir thermal exergies However additional glazing has a neg-ative effect on electrical exergy because of solar absorptionand reflection as observed by previous authors [30] Electricalexergy has higher contribution in total exergy output of aPVT panel compared with thermal exergy of a PVT panel


35

3

25

2

15

1

05

0

7 8 9 10 11 12 13 14 15 16 17 18 19

Day time

Model 2 PF = 07

Model 2 PF = 03

Model 1 PF = 07

Model 1 PF = 03

Delt

aT

Figure 7 Air temperature increase in Models 1 and 2

from the perspective of the second law of thermodynamics asingle-path bifacial PVT panel is preferable

33 Daily Simulation Monthly average hourly solar radia-tion and dry bulb temperature of Malaysia [50] were used toevaluate the bifacial PVTpanels Daily simulationwas carriedout by one-hour step time whereby the temperatures of PVpanel reflector and glazing at each step time were obtainedand used as initial data for the next step

As indicated by steady-state simulation panel Models 2and 1 were the best designs because of their performancesas based on the first and second laws of thermodynamicsrespectively

Model 2 had the highest output energy (Figure 3)whereas Model 1 had the highest output exergy (Figure 6)Therefore Models 1 and 2 were selected for daily simulationsFigure 7 shows daily outlet air temperature increase forModels 1 and 2 at a flow rate of 008 kgs in a typical day inMalaysian climate Output air temperature of Model 2 washigher than that of Model 1 (Figure 7)

Daily average energy and exergy efficiencies of Models1 and 2 were calculated (Figure 8) Model 2 had the highestdaily average energy efficiency among the four modelswhereasModel 1 had the highest daily exergy efficiency Dailyaverage efficiency of Model 2 was 20 higher than that ofModel 1 at the same flow rate but its exergy efficiency wasonly 035 lower than that ofModel 1Model 2 is preferred forapplications that demand high amount of low-grade energy(low-temperature thermal) whereas Model 1 is preferred forapplications that require high-quality energy (electrical)

The exergy efficiencies of the panels were improved byincreasing the packing factor from 03 to 07 Meanwhile theenergy efficiencies showed less dependence on the packingfactor This contrast is because total exergy output is mainlydependent on electrical energy output (see (10) and (14))whereas total energy output is mainly dependent on thermalenergy output (see (9))

4 Conclusions

Four air-based PVT panels were equipped with bifacialsolar panel and were studied based on the first and second

Ener

gy effi

cien

cy (

)

80

70

60

50

40

30

20

10

0PF = 07

PF = 05

PF = 03

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

(a)

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

PF = 07

PF = 05

PF = 03

Exer

gy effi

cien

cy (

)

10

9

8

7

6

5

4

3

(b)

Figure 8 Daily average efficiencies of Models 1 and 2 (a) energyand (b) exergy

laws of thermodynamics Double-path-parallel panel hadthe highest total energy efficiency (35 to 75) followedby double-path-counter flow panel double-path-returningflow panel and single-path panel However the single-pathpanel showed the highest exergy efficiency (448 to 1015)followed by double-path-parallel panel double-path-counterflow panel and double-path-returning flow panel Double-path panels have an additional glazing that improved thermalenergy and exergy efficiencies but have a negative effecton the electrical energy and exergy outputs Single-pathpanel is the best option if electrical energy is the desiredenergy output of the panel whereas double-path-parallelpanel is recommended for maximum thermal energy outputDaily energy and exergy simulations were performed underthe tropical climate of Malaysia Double-path-parallel panelrepresented a daily average energy efficiency that was 20higher than that of single-path panel However daily averageexergy efficiency of double-path-parallel panel was only


035 lower than that of single-path panel at the same flowrate PVT panels are mostly used for drying applications attropical climate of Malaysia the double-path-parallel panelis mostly recommended tomaximize thermal energy harvestThe harvested electrical energy could be used to run electricalcomponents of drying system such as air blowers and controlsystem High packing factor is preferable with regard to thefirst and second laws of thermodynamics Economic analysiswould be able to recommend the optimum packing factor

References

[1] T Uematsu Y Yazawa K Tsutsui et al ldquoDesign and character-ization of flat-plate static-concentrator photovoltaic modulesrdquoSolar Energy Materials and Solar Cells vol 67 no 1ndash4 pp 441ndash448 2001

[2] A Luque A Cuevas and J M Ruiz ldquoDouble-sided n+-p-n+solar cell for bifacial concentrationrdquo Solar Cells vol 2 no 2 pp151ndash166 1980

[3] A Huebner A G Aberle and R Hezel ldquoTemperature behaviorof monofacial and bifacial silicon solar cellsrdquo in Proceedings ofthe 26th IEEE Photovoltaic Specialists Conference pp 223ndash226October 1997

[4] T Joge Y Eguchi Y Imazu I Araki T Uematsu and KMatsukuma ldquoApplications and field tests of bifacial solar mod-ulesrdquo in Proceedings of the 29th IEEE Photovoltaic SpecialistsConference pp 1549ndash1552 May 2002

[5] A Moehlecke I Zanesco A C Pan T C Severo and A PMallmann ldquoPhotovoltaic module with coloured diffuse reflec-torsrdquo in Proceedings of the European Photovoltaic Solar EnergyConference pp 785ndash787 Munich Germany 2001

[6] L YangQHYeA Ebong et al ldquoHigh efficiency screen printedbifacial solar cells on monocrystalline CZ siliconrdquo Progress inPhotovoltaics vol 19 no 3 pp 275ndash279 2011

[7] P Ooshaksaraei K Sopian R Zulkifli M A Alghoul andS H Zaidi ldquoCharacterization of a bifacial photovoltaic panelintegrated with external diffuse and semimirror type reflectorsrdquoInternational Journal of Photoenergy vol 2013 Article ID465837 7 pages 2013

[8] C Duran H Deuser R Harney and T Buck ldquoApproaches to animproved IV and QE characterization of bifacial silicon solarcells and the prediction of their module performancerdquo EnergyProcedia vol 8 pp 88ndash93 2011

[9] P Ooshaksaraei R Zulkifli S H Zaidi M A Alghoul AZaharim and K Sopian ldquoTerrestrial applications of bifacialphotovoltaic solar panelsrdquo in Proceedings of the 10th Interna-tional Conference on System Science and Simulation in Engineer-ing pp 128ndash131World Scientific and EngineeringAcademy andSociety (WSEAS) Penang Malaysia 2011

[10] M L Vladislav Poulek and I Persic ldquoBifacial tracking con-centrator TRAXLE 5Xrdquo in Proceedings of the 2nd InternationalWorkshop on Concentraing Photovoltaic Powerplant OpticalDesign and Grid Conection 2009

[11] B Robles-Ocampo E Ruız-Vasquez H Canseco-Sanchez et alldquoPhotovoltaicthermal solar hybrid system with bifacial PVmodule and transparent plane collectorrdquo Solar EnergyMaterialsand Solar Cells vol 91 no 20 pp 1966ndash1971 2007

[12] M Brogren and B Karlsson ldquoLow-concentrating water-cooledPV-thermal hybrid systems for high latitudesrdquo in Proceedings ofthe 29th IEEE Photovoltaic Specialists Conference pp 1733ndash1736May 2002

[13] U Ortabasi K Firor and M Ilyin ldquoLow concentration photo-voltaic module design using bifacial solar cellsrdquo in Proceedingsof the 20th IEEE Photovoltaic Specialists Conference pp 1324ndash1326 September 1988

[14] U Ortabasi ldquoPerformance of a 2X cusp concentrator PVmodule using bifacial solar cellsrdquo inProceedings of the 26th IEEEConference Record of the Photovoltaic Specialists Conference(PVSC rsquo97) Anaheim Calif USA September 1997

[15] K J Weber V Everett P N K Deenapanray E Franklinand A W Blakers ldquoModeling of static concentrator modulesincorporating lambertian or v-groove rear reflectorsrdquo SolarEnergy Materials and Solar Cells vol 90 no 12 pp 1741ndash17492006

[16] R Hezel ldquoNovel applications of bifacial solar cellsrdquo Progress inPhotovoltaics vol 11 no 8 pp 549ndash556 2003

[17] S Yoon S Tak J Kim Y Jun K Kang and J Park ldquoApplicationof transparent dye-sensitized solar cells to building integratedphotovoltaic systemsrdquoBuilding and Environment vol 46 no 10pp 1899ndash1904 2011

[18] T Y Y Fung and H Yang ldquoStudy on thermal performanceof semi-transparent building-integrated photovoltaic glazingsrdquoEnergy and Buildings vol 40 no 3 pp 341ndash350 2008

[19] K Sopian K S Yigit H T Liu S Kakac and T N VezirogluldquoPerformance analysis of photovoltaic thermal air heatersrdquoEnergy Conversion and Management vol 37 no 11 pp 1657ndash1670 1996


[21] T T Chow ldquoA review on photovoltaicthermal hybrid solartechnologyrdquo Applied Energy vol 87 no 2 pp 365ndash379 2010

[22] R Kumar and M A Rosen ldquoA critical review of photovoltaic-thermal solar collectors for air heatingrdquo Applied Energy vol 88no 11 pp 3603ndash3614 2011

[23] M A Hasan and K Sumathy ldquoPhotovoltaic thermal moduleconcepts and their performance analysis a reviewrdquo Renewableand Sustainable Energy Reviews vol 14 no 7 pp 1845ndash18592010

[24] X Zhang X Zhao S Smith J Xu and X Yu ldquoReview ofRampD progress and practical application of the solar photo-voltaicthermal (PVT) technologiesrdquo Renewable and Sustain-able Energy Reviews vol 16 no 1 pp 599ndash617 2012

[25] D Kamthania S Nayak and G N Tiwari ldquoPerformanceevaluation of a hybrid photovoltaic thermal double pass facadefor space heatingrdquo Energy and Buildings vol 43 no 9 pp 2274ndash2281 2011

[26] K E Park G H Kang H I Kim G J Yu and J TKim ldquoAnalysis of thermal and electrical performance of semi-transparent photovoltaic (PV) modulerdquo Energy vol 35 no 6pp 2681ndash2687 2010

[27] J A Duffie and W A Beckman Solar Engineering of ThermalProcesses John Wiley amp Sons 2nd edition 1980

[28] F P Incropera D P DeWitt T L Bergman and A S LavineFundamentals of Heat and Mass Transfer John Wiley amp Sons6th edition 1994

[29] H M Tan and W W S Charters ldquoEffect of thermal entranceregion on turbulent forced-convective heat transfer for anasymmetrically heated rectangular ductwith uniformheat fluxrdquoSolar Energy vol 12 no 4 pp 513ndash516 1969


[30] A Shahsavar and M Ameri ldquoExperimental investigation andmodeling of a direct-coupled PVT air collectorrdquo Solar Energyvol 84 no 11 pp 1938ndash1958 2010

[31] D L Evans ldquoSimplified method for predicting photovoltaicarray outputrdquo Solar Energy vol 27 no 6 pp 555ndash560 1981

[32] F Sarhaddi S Farahat H Ajam A Behzadmehr and MMahdaviAdeli ldquoAn improved thermal and electricalmodel for asolar photovoltaic thermal (PVT) air collectorrdquoApplied Energyvol 87 no 7 pp 2328ndash2339 2010

[33] J Ji J-P Lu T-T Chow W He and G Pei ldquoA sensitivity studyof a hybrid photovoltaicthermal water-heating system withnatural circulationrdquo Applied Energy vol 84 no 2 pp 222ndash2372007

[34] A Bejan G Tsatsaronis and M Moran Thermal Design andOptimization John Wiley amp Sons 1996

[35] T T Chow G Pei K F Fong Z Lin A L S Chan and J JildquoEnergy and exergy analysis of photovoltaic-thermal collectorwith and without glass coverrdquo Applied Energy vol 86 no 3 pp310ndash316 2009

[36] F Sarhaddi S Farahat H Ajam andA Behzadmehr ldquoExergeticperformance assessment of a solar photovoltaic thermal (PVT)air collectorrdquo Energy and Buildings vol 42 no 11 pp 2184ndash21992010

[37] M Bosanac B Sorensen I Katic H Sorensen B Nielsenand J Badran PhotovoltaicThermal Solar Collectors and TheirPotential in Denmark EFP 2003

[38] A S Joshi and A Tiwari ldquoEnergy and exergy efficiencies of ahybrid photovoltaic-thermal (PVT) air collectorrdquo RenewableEnergy vol 32 no 13 pp 2223ndash2241 2007

[39] H Ajam S Farahat and F Sarhaddi ldquoExergetic optimizationof solar air heaters and comparison with energy analysisrdquoInternational Journal of Thermodynamics vol 8 no 4 pp 183ndash190 2005

[40] A S Joshi I Dincer and B V Reddy ldquoThermodynamicassessment of photovoltaic systemsrdquo Solar Energy vol 83 no8 pp 1139ndash1149 2009

[41] S Kumar G Singh G N Tiwari and J K Yadav ldquoThermalmodelling of a hybrid photovoltaic thermal water heater inparallel configurationrdquo International Journal of SustainableEnergy vol 35 no 5 pp 277ndash295 2013

[42] D Ibrahim and S J Anand ldquoSolar PV and PVT Systemsrdquo inEncyclopedia of Energy EngIneerIng and Technology pp 1ndash26Taylor amp Francis 2008

[43] T Fujisawa and T Tani ldquoAnnual exergy evaluation onphotovoltaic-thermal hybrid collectorrdquo Solar Energy Materialsand Solar Cells vol 47 no 1ndash4 pp 135ndash148 1997

[44] L Borel and D Favrat Thermodynamics and Energy SystemsAnalysis from Energy to Exergy CRC Press 2010

[45] R Petela ldquoExergy of undiluted thermal radiationrdquo Solar Energyvol 74 no 6 pp 469ndash488 2003

[46] A Hepbasli ldquoA key review on exergetic analysis and assessmentof renewable energy resources for a sustainable futurerdquo Renew-able and Sustainable Energy Reviews vol 12 no 3 pp 593ndash6612008

[47] S Nayak and G N Tiwari ldquoEnergy and exergy analysisof photovoltaicthermal integrated with a solar greenhouserdquoEnergy and Buildings vol 40 no 11 pp 2015ndash2021 2008

[48] K Sopian H T Liu S Kakac and T N Veziroglu ldquoPerfor-mance of a double pass photovoltaic thermal solar collectorsuitable for solar drying systemsrdquo Energy Conversion andManagement vol 41 no 4 pp 353ndash365 2000

[49] J K Tonui and Y Tripanagnostopoulos ldquoAir-cooled PVT solarcollectors with low cost performance improvementsrdquo SolarEnergy vol 81 no 4 pp 498ndash511 2007

[50] M Z Hussin M H A Hamid Z M Zain and R ARahman ldquoAn evaluation data of solar irradiation and dry bulbtemperature at Subang underMalaysian climaterdquo in Proceedingsof the IEEE Control and System Graduate Research Colloquium(ICSGRC rsquo10) pp 55ndash60 June 2010

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


Solar radiation

Solar radiation

Reflector

Monofacial solar cell

Front surface

Back contact

(a)

Bifacial solar cell

Rear surface

Solar radiation

Solar radiation

Reflector

Front surface

(b)

Figure 1 Radiation absorptions of monofacial and bifacial PV solar cells

installation attitude of the reflector Three key parametershave significant effects on panel performance panel slopereflector slope and reflection efficiency However bifacialsolar panels are effective without a reflector in certainapplications [10ndash14] In general solar panels are classifiedeither as one-sun (1X) panel or concentrator panel (multi-X) For bifacial panels the definition of 1X panel and multi-X panel may overlap The front surface of a bifacial cellreceives 1X solar radiation whereas the rear surface mayreceive additional 1X beam radiation [15] Reflection propertyof the reflector depends on surface roughness and colorA wide range of reflectors including diffuse mirror andsemitransparent have been studied [1 10 11 16] Uematsu[1] developed a flat plate bifacial panel by adding a static V-groove concentrator to provide 1X solar radiation on the rearsurface of the bifacial cell which resulted in 856 powerenhancement

Intensity of solar radiation on the rear surface affectsthe power generated by a bifacial PV panel [8] Moehleckeet al [5] studied the reflection properties of painted reflectorsplaced beneath the bifacial solar cells They observed upto 25 enhancement in solar absorption compared withconventional monofacial panels White-colored reflector isthe optimum painted reflector with 75 average reflectanceYellow is the second best color for reflectors followed byorange red green blue brown purple grey dark blue anddark green colors which give 61 to 32 reflection [5]

13 Residential Applications of Bifacial Solar Cells Building-integrated applications of monofacial PV and PVT pan-els have been widely studied whereas the performance ofbuilding-integrated bifacial solar panels has not Bifacial PVpanels could be integrated into residential and commercialbuildings as window-integrated wall-integrated or parkinglot-integrated panels [9]

Bifacial solar cells partially cover the panel area In wall-integrated application the panel is installed with an offsetdistance from the wall Front surface of bifacial solar cellsabsorb a portion of solar radiation whereas a portion ofsolar radiation penetrates through transparent vacant space

between cells the wall reflects light back to the rear surfaceof bifacial cells [16]

Window-integrated bifacial PV panels produce electricalenergy while permitting penetration of faint solar radiationinto the interior area for lighting of residential or commercialbuildings [9 17] Packing factor of solar panel has significantimpact on the amount of solar radiation that penetratesthe PV module [18] Space heating and drying applicationscould also be considered depending on the climate of theinstallation site

14 Air-Based PVT Panel Air-based PVT collectors areuseful for both industrial and residential applications suchas drying and space heating Air-based panel designs areclassified according to the number or glazing and air-pathSingle-glazing double-path (monofacial) panels have higherelectrical and thermal efficiencies compared with single-pathpanel types [19] In an air-based PVT panel PV cells areplaced at the top of the absorber plate and absorb a portion ofsolar radiation that reaches the front surface The remainingportion of solar radiation penetrates the PV cells and reachesthe absorber plate where it is converted into thermal energy

Substituting monofacial PV cells with bifacial PV cellshas led to the development of bifacial PVT panels A bifacialPVT panel equipped with aluminum reflector generates 40additional electrical and thermal energies [20]

Most of the existing PVT panel designs are inappropriatefor bifacial solar cells because the absorber plate covers therear surface of bifacial solar cells [21ndash24] Absence of solarradiation on the rear surface of bifacial solar cells misses thebenefit of dual surface solar radiation absorption of bifacialsolar cells Panel modification is essential the absorber plateshould be substituted by a reflector to reflect back solarradiation to the rear surface of bifacial solar cells

The current research aims to develop new designs ofair-based PVT panels based on bifacial solar cells and toevaluate the performance of the panel with regard to the firstand second laws of thermodynamics This paper representssteady-state simulation and daily simulation based on theclimate of Malaysia



Air flow



Air flow 2

Glass


(b)


Air flow 2

Glass


(c)


Air flow 2

Glass


(d)


















ℎ119888

= 28 + 119906Air (1)



ℎ119888

=119870Air119863119867

119873119906 (2)

where ℎ119888


ℎ119888

= 00182Re08Pr04 [1 + 1198781015840119863119867119871] (3)

where

1198781015840

= 143 log( 119871

119863119867

) minus 79 for 0 lt (119871

119863119867

) le 60

= 175 for 60 lt (119871

119863119867

)

(4)

Re =120588119906119863

120583

Pr = 07

(5)




(6)







120578Th =119862119901

(119879119900

minus 119879119894

)

119878 times 119860 (8)


120578Total = 120578Th +120578El









Tota

l effi

cien

cy (

)90

80

70

60

50

40

30

20

10

002 004 006 008 01 012 014

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Packing factor = 1

(a)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)

90

80

70

60

50

40

30

20

10

Packing factor = 07

002 004 006 008 01 012 014

(b)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)

90

80

70

60

50

40

30

20

10

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)90

80

70

60

50

40

30

20

10

Packing factor = 03

002 004 006 008 01 012 014

(d)









ExEl = EnEl




ExTh = 119862119901

[1198792

minus 1198791

minus 119879119886

(ln 11987921198791

+120574 minus 1

120574ln 11987511198752

)] (12)

where 119879119886


1198792

1198751

and 1198752




3(119879119886

119879sun) +

1

3(119879119886

119879sun)

4

] (13)



(14)






Model 2Model 3

Model 4Model 1

Elec

tric

al ex

ergy

effici

ency

()

84

83

82

81

8

79

78


Packing factor = 07

002 004 006 008 01 012 014


Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Ther

mal

exer

gy effi

cien

cy (

)06

05

04

03

02

01

0

Packing factor = 07

002 004 006 008 01 012 014





Tota

l exe

rgy

effici

ency

()

102

101

10

99

98

97

96

Flow rate (kgs)


Model 1

Packing factor = 1

002 004 006 008 01 012 014

(a)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

86

85

84

83

82

81

8

Packing factor = 07

002 004 006 008 01 012 014

(b)

Tota

l exe

rgy

effici

ency

()

69

68

68

67

67

66

66

65

65

64

Flow rate (kgs)


Model 1

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

45

45

44

44

43

43

42

Packing factor = 03

002 004 006 008 01 012 014

(d)








35

3

25

2

15

1

05

0

7 8 9 10 11 12 13 14 15 16 17 18 19

Day time

Model 2 PF = 07

Model 2 PF = 03

Model 1 PF = 07

Model 1 PF = 03

Delt

aT








4 Conclusions


Ener

gy effi

cien

cy (

)

80

70

60

50

40

30

20

10

0PF = 07

PF = 05

PF = 03

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

(a)

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

PF = 07

PF = 05

PF = 03

Exer

gy effi

cien

cy (

)

10

9

8

7

6

5

4

3

(b)





References





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



Air flow



Air flow 2

Glass


(b)


Air flow 2

Glass


(c)


Air flow 2

Glass


(d)


















ℎ119888

= 28 + 119906Air (1)



ℎ119888

=119870Air119863119867

119873119906 (2)

where ℎ119888


ℎ119888

= 00182Re08Pr04 [1 + 1198781015840119863119867119871] (3)

where

1198781015840

= 143 log( 119871

119863119867

) minus 79 for 0 lt (119871

119863119867

) le 60

= 175 for 60 lt (119871

119863119867

)

(4)

Re =120588119906119863

120583

Pr = 07

(5)




(6)







120578Th =119862119901

(119879119900

minus 119879119894

)

119878 times 119860 (8)


120578Total = 120578Th +120578El









Tota

l effi

cien

cy (

)90

80

70

60

50

40

30

20

10

002 004 006 008 01 012 014

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Packing factor = 1

(a)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)

90

80

70

60

50

40

30

20

10

Packing factor = 07

002 004 006 008 01 012 014

(b)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)

90

80

70

60

50

40

30

20

10

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)90

80

70

60

50

40

30

20

10

Packing factor = 03

002 004 006 008 01 012 014

(d)









ExEl = EnEl




ExTh = 119862119901

[1198792

minus 1198791

minus 119879119886

(ln 11987921198791

+120574 minus 1

120574ln 11987511198752

)] (12)

where 119879119886


1198792

1198751

and 1198752




3(119879119886

119879sun) +

1

3(119879119886

119879sun)

4

] (13)



(14)






Model 2Model 3

Model 4Model 1

Elec

tric

al ex

ergy

effici

ency

()

84

83

82

81

8

79

78


Packing factor = 07

002 004 006 008 01 012 014


Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Ther

mal

exer

gy effi

cien

cy (

)06

05

04

03

02

01

0

Packing factor = 07

002 004 006 008 01 012 014





Tota

l exe

rgy

effici

ency

()

102

101

10

99

98

97

96

Flow rate (kgs)


Model 1

Packing factor = 1

002 004 006 008 01 012 014

(a)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

86

85

84

83

82

81

8

Packing factor = 07

002 004 006 008 01 012 014

(b)

Tota

l exe

rgy

effici

ency

()

69

68

68

67

67

66

66

65

65

64

Flow rate (kgs)


Model 1

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

45

45

44

44

43

43

42

Packing factor = 03

002 004 006 008 01 012 014

(d)








35

3

25

2

15

1

05

0

7 8 9 10 11 12 13 14 15 16 17 18 19

Day time

Model 2 PF = 07

Model 2 PF = 03

Model 1 PF = 07

Model 1 PF = 03

Delt

aT








4 Conclusions


Ener

gy effi

cien

cy (

)

80

70

60

50

40

30

20

10

0PF = 07

PF = 05

PF = 03

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

(a)

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

PF = 07

PF = 05

PF = 03

Exer

gy effi

cien

cy (

)

10

9

8

7

6

5

4

3

(b)





References





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










ℎ119888

= 28 + 119906Air (1)



ℎ119888

=119870Air119863119867

119873119906 (2)

where ℎ119888


ℎ119888

= 00182Re08Pr04 [1 + 1198781015840119863119867119871] (3)

where

1198781015840

= 143 log( 119871

119863119867

) minus 79 for 0 lt (119871

119863119867

) le 60

= 175 for 60 lt (119871

119863119867

)

(4)

Re =120588119906119863

120583

Pr = 07

(5)




(6)







120578Th =119862119901

(119879119900

minus 119879119894

)

119878 times 119860 (8)


120578Total = 120578Th +120578El









Tota

l effi

cien

cy (

)90

80

70

60

50

40

30

20

10

002 004 006 008 01 012 014

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Packing factor = 1

(a)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)

90

80

70

60

50

40

30

20

10

Packing factor = 07

002 004 006 008 01 012 014

(b)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)

90

80

70

60

50

40

30

20

10

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)90

80

70

60

50

40

30

20

10

Packing factor = 03

002 004 006 008 01 012 014

(d)









ExEl = EnEl




ExTh = 119862119901

[1198792

minus 1198791

minus 119879119886

(ln 11987921198791

+120574 minus 1

120574ln 11987511198752

)] (12)

where 119879119886


1198792

1198751

and 1198752




3(119879119886

119879sun) +

1

3(119879119886

119879sun)

4

] (13)



(14)






Model 2Model 3

Model 4Model 1

Elec

tric

al ex

ergy

effici

ency

()

84

83

82

81

8

79

78


Packing factor = 07

002 004 006 008 01 012 014


Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Ther

mal

exer

gy effi

cien

cy (

)06

05

04

03

02

01

0

Packing factor = 07

002 004 006 008 01 012 014





Tota

l exe

rgy

effici

ency

()

102

101

10

99

98

97

96

Flow rate (kgs)


Model 1

Packing factor = 1

002 004 006 008 01 012 014

(a)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

86

85

84

83

82

81

8

Packing factor = 07

002 004 006 008 01 012 014

(b)

Tota

l exe

rgy

effici

ency

()

69

68

68

67

67

66

66

65

65

64

Flow rate (kgs)


Model 1

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

45

45

44

44

43

43

42

Packing factor = 03

002 004 006 008 01 012 014

(d)








35

3

25

2

15

1

05

0

7 8 9 10 11 12 13 14 15 16 17 18 19

Day time

Model 2 PF = 07

Model 2 PF = 03

Model 1 PF = 07

Model 1 PF = 03

Delt

aT








4 Conclusions


Ener

gy effi

cien

cy (

)

80

70

60

50

40

30

20

10

0PF = 07

PF = 05

PF = 03

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

(a)

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

PF = 07

PF = 05

PF = 03

Exer

gy effi

cien

cy (

)

10

9

8

7

6

5

4

3

(b)





References





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Tota

l effi

cien

cy (

)90

80

70

60

50

40

30

20

10

002 004 006 008 01 012 014

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Packing factor = 1

(a)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)

90

80

70

60

50

40

30

20

10

Packing factor = 07

002 004 006 008 01 012 014

(b)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)

90

80

70

60

50

40

30

20

10

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Tota

l effi

cien

cy (

)90

80

70

60

50

40

30

20

10

Packing factor = 03

002 004 006 008 01 012 014

(d)









ExEl = EnEl




ExTh = 119862119901

[1198792

minus 1198791

minus 119879119886

(ln 11987921198791

+120574 minus 1

120574ln 11987511198752

)] (12)

where 119879119886


1198792

1198751

and 1198752




3(119879119886

119879sun) +

1

3(119879119886

119879sun)

4

] (13)



(14)






Model 2Model 3

Model 4Model 1

Elec

tric

al ex

ergy

effici

ency

()

84

83

82

81

8

79

78


Packing factor = 07

002 004 006 008 01 012 014


Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Ther

mal

exer

gy effi

cien

cy (

)06

05

04

03

02

01

0

Packing factor = 07

002 004 006 008 01 012 014





Tota

l exe

rgy

effici

ency

()

102

101

10

99

98

97

96

Flow rate (kgs)


Model 1

Packing factor = 1

002 004 006 008 01 012 014

(a)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

86

85

84

83

82

81

8

Packing factor = 07

002 004 006 008 01 012 014

(b)

Tota

l exe

rgy

effici

ency

()

69

68

68

67

67

66

66

65

65

64

Flow rate (kgs)


Model 1

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

45

45

44

44

43

43

42

Packing factor = 03

002 004 006 008 01 012 014

(d)








35

3

25

2

15

1

05

0

7 8 9 10 11 12 13 14 15 16 17 18 19

Day time

Model 2 PF = 07

Model 2 PF = 03

Model 1 PF = 07

Model 1 PF = 03

Delt

aT








4 Conclusions


Ener

gy effi

cien

cy (

)

80

70

60

50

40

30

20

10

0PF = 07

PF = 05

PF = 03

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

(a)

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

PF = 07

PF = 05

PF = 03

Exer

gy effi

cien

cy (

)

10

9

8

7

6

5

4

3

(b)





References





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



ExTh = 119862119901

[1198792

minus 1198791

minus 119879119886

(ln 11987921198791

+120574 minus 1

120574ln 11987511198752

)] (12)

where 119879119886


1198792

1198751

and 1198752




3(119879119886

119879sun) +

1

3(119879119886

119879sun)

4

] (13)



(14)






Model 2Model 3

Model 4Model 1

Elec

tric

al ex

ergy

effici

ency

()

84

83

82

81

8

79

78


Packing factor = 07

002 004 006 008 01 012 014


Flow rate (kgs)

Model 2Model 3

Model 4Model 1

Ther

mal

exer

gy effi

cien

cy (

)06

05

04

03

02

01

0

Packing factor = 07

002 004 006 008 01 012 014





Tota

l exe

rgy

effici

ency

()

102

101

10

99

98

97

96

Flow rate (kgs)


Model 1

Packing factor = 1

002 004 006 008 01 012 014

(a)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

86

85

84

83

82

81

8

Packing factor = 07

002 004 006 008 01 012 014

(b)

Tota

l exe

rgy

effici

ency

()

69

68

68

67

67

66

66

65

65

64

Flow rate (kgs)


Model 1

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

45

45

44

44

43

43

42

Packing factor = 03

002 004 006 008 01 012 014

(d)








35

3

25

2

15

1

05

0

7 8 9 10 11 12 13 14 15 16 17 18 19

Day time

Model 2 PF = 07

Model 2 PF = 03

Model 1 PF = 07

Model 1 PF = 03

Delt

aT








4 Conclusions


Ener

gy effi

cien

cy (

)

80

70

60

50

40

30

20

10

0PF = 07

PF = 05

PF = 03

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

(a)

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

PF = 07

PF = 05

PF = 03

Exer

gy effi

cien

cy (

)

10

9

8

7

6

5

4

3

(b)





References





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Tota

l exe

rgy

effici

ency

()

102

101

10

99

98

97

96

Flow rate (kgs)


Model 1

Packing factor = 1

002 004 006 008 01 012 014

(a)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

86

85

84

83

82

81

8

Packing factor = 07

002 004 006 008 01 012 014

(b)

Tota

l exe

rgy

effici

ency

()

69

68

68

67

67

66

66

65

65

64

Flow rate (kgs)


Model 1

Packing factor = 05

002 004 006 008 01 012 014

(c)

Flow rate (kgs)


Model 1

Tota

l exe

rgy

effici

ency

()

45

45

44

44

43

43

42

Packing factor = 03

002 004 006 008 01 012 014

(d)








35

3

25

2

15

1

05

0

7 8 9 10 11 12 13 14 15 16 17 18 19

Day time

Model 2 PF = 07

Model 2 PF = 03

Model 1 PF = 07

Model 1 PF = 03

Delt

aT








4 Conclusions


Ener

gy effi

cien

cy (

)

80

70

60

50

40

30

20

10

0PF = 07

PF = 05

PF = 03

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

(a)

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

PF = 07

PF = 05

PF = 03

Exer

gy effi

cien

cy (

)

10

9

8

7

6

5

4

3

(b)





References





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


35

3

25

2

15

1

05

0

7 8 9 10 11 12 13 14 15 16 17 18 19

Day time

Model 2 PF = 07

Model 2 PF = 03

Model 1 PF = 07

Model 1 PF = 03

Delt

aT








4 Conclusions


Ener

gy effi

cien

cy (

)

80

70

60

50

40

30

20

10

0PF = 07

PF = 05

PF = 03

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

(a)

Mod

el1

003

(kg

s)

Mod

el1

008

(kg

s)

Mod

el1

014

(kg

s)

Mod

el2

003

(kg

s)

Mod

el2

008

(kg

s)

Mod

el2

014

(kg

s)

PF = 07

PF = 05

PF = 03

Exer

gy effi

cien

cy (

)

10

9

8

7

6

5

4

3

(b)





References





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



References





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

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