Mediterranean Green Buildings & Renewable Energy pp 429-444 | Cite as

# Performance Analysis and Parametric Studies of a Bi-fluid Type Photovoltaic/Thermal (PV/T) Solar Collector in Simultaneous Mode Under Tropical Climate Conditions

## Abstract

Performance analysis of a photovoltaic/thermal solar collector with a bi-fluid configuration (air and water) was conducted under real sky conditions in the tropical climate of Perlis, Northern Peninsular Malaysia. In addition to the electricity generated, this type of collector has enabled three different modes of fluid operation: air mode, water mode and simultaneous (bi-fluid) mode. The third mode of fluid of operation is the primary focus in this chapter. This chapter highlights the performance of the collector outdoors, in terms of the experimental and two-dimensional theoretical analysis at steady state. For collector testing under real sky conditions, analyses of the collector for varying sets of mass flow rates under environmental conditions of an average wind speed of 3 m/s and average solar radiation of 700 W/m^{2} were conducted. To obtain suitable data, experiments were conducted for each of the mass flow rates on ten different days of testing. For the simultaneous mode, when air flow rate was fixed at 0.0262 kg/s, at a water mass flow rate that varied from 0.0017 to 0.010 kg/s, the electrical efficiency and total thermal efficiency ranged from 8.13 to 8.60 % and 44.36 to 47.45 % respectively. When the water flow rate was fixed at 0.0066 kg/s, at an air mass flow rate that varied from 0.0092 to 0.0753 kg/s, the efficiencies ranged from 8.10 to 8.56 % and 44.06 to 50.37 % respectively. Theoretical analysis was then conducted and compared with the experimental analysis by comparing the trend of the curves and using mean absolute percentage error (MAPE) analysis. The curves were found to be in good agreement, and the computed MAPE for the fluids’ output temperature was less than 2 %. Parametric studies were then conducted to investigate the performance of the collector with the change in air channel depth and performance with the change in collector length. The feasibility of incorporating two different types of working fluid into the same PV/T solar collector was demonstrated based on the thermal and electrical energy output of the collector under real sky conditions. Therefore, this research will serve as a starting point for further research into a bi-fluid type PV/T solar collector, both experimentally and theoretically.

## Keywords

Bi-fluid Photovoltaic thermal (PV/T) 2-D steady state Outdoor Parametric## Nomenclature

*A*_{PV}Collector aperture area’s subsegment, equal to area of PV module’s subsegment (m

^{2})*C*_{f}Conversion power factor

*C*_{pf1}Specific heat capacity of air

*C*_{pf2}Specific heat capacity of water

*D*_{i}Inner pipe diameter

*D*_{o}Outer pipe diameter

*f*A general subscript to denote a fluid

*f*_{r}A friction factor in a fluid’s channel

*G*Global radiation

*h*Heat transfer coefficient (W/m

^{2}K)*h*_{cvbs f1}Convection heat transfer coefficient from back surface of Tedlar to air flow (W/m

^{2}K)*h*_{cvbsf2}Convection heat transfer coefficient from back surface of Tedlar to water flow (W/m

^{2}K)*h*_{cvfin f1}Convection heat transfer coefficient from surface of a fin to flowing air (W/m

^{2}K)*h*_{cvw}Wind convection heat transfer coefficient (W/m

^{2}K)*h*_{i}Generalised notation for heat transfer coefficient of linear equations derived from developed energy balance equations for a general heat transfer coefficient

*i*(W/m^{2}K)*h*_{rbsbp}Radiation heat transfer coefficient between inner surfaces of collector (W/m

^{2}K)*h*_{rpvsky}Radiation heat transfer coefficient from PV cells to sky (W/m

^{2}K)*k*_{fin}Thermal conductivity of fin (W/mK)

*k*_{f1}Thermal conductivity of air (W/mK)

*k*_{f2}Thermal conductivity of water (W/mK)

*k*_{PV}Thermal conductivity of photovoltaic cells (W/mK)

*L*_{fin}Length of fin (m)

*m*Subsegment for each temperature node

- \( {\overset{.}{m}}_{f1} \)
Air mass flow rate (kg/s)

- \( {\overset{.}{m}}_{f2} \)
Water mass flow rate (kg/s)

*N*_{fin}Total number of fins

- \( {\displaystyle \sum }{Q}_{\mathrm{th},\mathrm{inst}} \)
Total instantaneous thermal energy produced by solar collector (J)

- \( {\displaystyle \sum }{Q}_{\mathrm{PVT},\mathrm{inst}} \)
Instantaneous primary energy saving (J)

*q*Rate of heat flux (W/m

^{2})*q*_{uf1, m}Rate of heat transfer per unit area for air nodes (W/m)

*q*_{uf2, m}Rate of heat transfer per unit area for air nodes (W/m)

- Re
Reynolds number

*S*_{PV}Total rate of solar energy absorbed by solar cells of PV module

*S*_{T}Total energy absorbed by Tedlar

*T*Temperature (K)

*T*_{a}Ambient temperature (K)

*T*_{bp, m}Temperature nodes of surface of back plate (K)

*T*_{bs, m}Temperature nodes of back surface of Tedlar (K)

*T*_{bp}Mean temperature of surface of back plate with fins (K)

*T*_{bs}Mean temperature of back surface of Tedlar (K)

*T*_{PV}Mean temperature of cell (K)

*T*_{f1, m}Temperature nodes of air flow in channel (K)

*T*_{f2, m}Temperature nodes of water flow in copper pipe (K)

*T*_{fin, m}Mean temperature of fin at subsegment

*m*(K)*T*_{PV, m}Temperature nodes of PV cells (at centre of cells) (K)

*T*_{ref}Temperature at reference point

*T*_{sky}Sky temperature (K)

*T*_{tin}Mean inner wall temperature of copper pipe (K)

*U*_{t, m}Overall top heat loss coefficient for subsegment

*m**v*_{f1}Maximum velocity of air (m/s)

*v*_{w}Wind speed (m/s)

*W*Tube spacing (m)

*α*_{c}Absorptance of PV cells

*β*_{c}PV module packing factor

*β*_{ref}Temperature coefficient at reference temperature

*δ*_{PV}Thickness of PV module

*δ*_{si}Thickness of Si-cells

*δ*_{T}Thickness of Tedlar layer

*δ*_{EVA}Thickness of ethylene-vinyl acetate (EVA) layer

*δ*_{fin}Fin thickness

- Δ
*y*_{PV}Δ*x* Area of subsegment of PV module

- Δ
*x* Distance between temperature nodes (\( \Delta x=1\kern0.5em \mathrm{cm} \))

*ε*_{sky}Emissivity of sky

*ε*_{g}Emissivity of glass cover

*γ*_{bsbp, m}Area correction factor for heat transfer from back surface of Tedlar to surface of back plate with fins

*γ*_{bs f1, m}Area correction factor for heat transfer from back surface of Tedlar to flowing air

*γ*_{bs f2, m}Area correction factor for heat transfer from back surface of Tedlar to flowing water

*γ*_{fin f1, m}Area correction factor for heat transfer from fin surfaces to flowing air

*γ*_{bp f1, m}Area correction factor for heat transfer from surface of back plate with fins to flowing air

*γ*_{bpa, m}Area correction factor for heat transfer from surface of back plate with fins to ambient

*τ*_{g}Transmittance factor of front cover glass of PV module

*η*Efficiency

*η*_{c}Electrical efficiency of PV cell

*η*_{ele}Electrical efficiency

*η*_{eth}Electrical efficiency converted to equivalent thermal efficiency

*η*_{fin}Fin efficiency

*η*_{p}Fin effectiveness

*η*_{Tref}Electrical efficiency at reference temperature

*η*_{th f1}Thermal efficiency of air

*η*_{th f2}Thermal efficiency of water

- \( {\displaystyle \sum }{\eta}_{\mathrm{th}} \)
Total thermal efficiency of solar collector

- \( {\displaystyle \sum }{\eta}_{\mathrm{PVT}} \)
Primary energy savings or equivalent thermal efficiency

- \( {\displaystyle \sum }{\eta}_{\mathrm{th},\mathrm{inst}} \)
Instantaneous total thermal efficiency of solar collector

## References

- 1.Wolf M (1976) Performance analyses of combined heating and photovoltaic power systems for residences. Energy Convers 16:79–90CrossRefGoogle Scholar
- 2.Florschuetz LW (1979) Extension of the Hottel-Whillier model to the analysis of combined photovoltaic/thermal flat plate collectors. Sol Energy 22:361–366CrossRefGoogle Scholar
- 3.Tripanagnostopoulos Y (2007) Aspects and improvements of hybrid photovoltaic/thermal solar energy systems. Sol Energy 81:1117–1131CrossRefGoogle Scholar
- 4.Assoa YB, Menezo C, Fraisse G, Yezou R, Brau J (2007) Study of a new concept of photovoltaic–thermal hybrid collector. Sol Energy 81:1132–1143CrossRefGoogle Scholar
- 5.Abu Bakar MN, Othman M, Hj Din M, Manaf NA, Jarimi H (2014) Design concept and mathematical model of a bi-fluid photovoltaic/thermal (PV/T) solar collector. Renew Energy 67:153–164CrossRefGoogle Scholar
- 6.Jarimi H, Abu Bakar MN, Manaf NA, Othman M, Din M (2013) Mathematical modelling of a finned bi-fluid type photovoltaic/thermal (PV/T) solar collector. In IEEE Conference on Clean Energy and Technology (CEAT), 2013, pp 163–168Google Scholar
- 7.Tonui JK, Tripanagnostopoulos Y (2007) Air-cooled PV/T solar collectors with low cost performance improvements. Sol Energy 81:498–511CrossRefGoogle Scholar
- 8.Chow TT, Pei G, Fong KF, Lin Z, Chan ALS, Ji J (2009) Energy and exergy analysis of photovoltaic–thermal collector with and without glass cover. Appl Energy 86:310–316CrossRefGoogle Scholar
- 9.Fujisawa T, Tani T (1997) Annual exergy evaluation on photovoltaic-thermal hybrid collector. Sol Energy Mater Sol Cells 47:135–148CrossRefGoogle Scholar
- 10.Joshi AS, Tiwari A (2007) Energy and exergy efficiencies of a hybrid photovoltaic–thermal (PV/T) air collector. Renew Energy 32:2223–2241CrossRefGoogle Scholar
- 11.Sarhaddi F, Farahat S, Ajam H, Behzadmehr A (2010) Exergetic performance assessment of a solar photovoltaic thermal (PV/T) air collector. Energy Build 42:2184–2199CrossRefGoogle Scholar
- 12.PVT Roadmap (2006) PVT ROADMAP A European guide for the development and market introduction of PV-Thermal technologyGoogle Scholar
- 13.Huang BJ, Lin TH, Hung WC, Sun FS (2001) Performance evaluation of solar photovoltaic/thermal systems. Sol Energy 70:443–448CrossRefGoogle Scholar
- 14.Mishra RK, Tiwari GN (2013) Energy and exergy analysis of hybrid photovoltaic thermal water collector for constant collection temperature mode. Sol Energy 90:58–67CrossRefGoogle Scholar
- 15.Fudholi A, Sopian K, Yazdi MH, Ruslan MH, Ibrahim A, Kazem HA (2014) Performance analysis of photovoltaic thermal (PVT) water collectors. Energy Convers Manag 78:641–651CrossRefGoogle Scholar
- 16.Suruhanjaya Tenaga (Energy Comissions) (2012) Industri Pembekalan Elektrik di Malaysia Maklumat dan Prestasi Statistik 2012. ed. Putrajaya Malaysia: Suruhanjaya Tenaga (Energy Comissions)Google Scholar
- 17.Othman MY, Yatim B, Sopian K, Abu Bakar MN (2007) Performance studies on a finned double-pass photovoltaic-thermal (PV/T) solar collector. Desalination 209:43–49CrossRefGoogle Scholar
- 18.Duffie JA, Beckman WA (2006) Solar engineering of thermal processes. Wiley, New YorkGoogle Scholar
- 19.Swinbank WC (1963) Longwave radiation from clear skies. Q J Roy Meteorol Soc 89(381):339–348CrossRefGoogle Scholar
- 20.Abu Bakar MN, Hj Othman MY (2013) Teknologi pengumpul suria fotovolta terma. Penerbit Universiti Kebangsaan Malaysia, MalaysiaGoogle Scholar
- 21.Sopian K, Yigit KS, Liu HT, Kakaç S, Veziroglu TN (1996) Performance analysis of photovoltaic thermal air heaters. Energy Convers Manag 37:1657–1670CrossRefGoogle Scholar
- 22.Tiwari A, Sodha MS (2006) Performance evaluation of solar PV/T system: an experimental validation. Sol Energy 80:751–759CrossRefGoogle Scholar

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