Page 156 - IJES Special Issues for AIEC2016

56 © Al-Shamani, Mat, Ruslan, Abed, and Sopian 2016 | Effect of New Ellipse Design

overall =th pv 1 .  exp AcUL F ' 
1
FR  mCp *    . 5
AcU L
The thermal performance of the PV/T collector m Cp .
is influenced by the parameter of the system
design and operating conditions. In this study, The corrected fin efficiency (F′) is calculated
the system was analyzed with various confi- using
gurations of ambient temperature, solar radi-
ation, and flow rate conditions. Based on this  1 
 
assumption, the thermal performance th of the UL
PV/T unit was evaluated for its thermal and PV F'    D)F  6
performance. Thus, the derivation of the  
efficiency parameters based on the Hottel– W  ( D  1  1  1  
Whillier equations (Hottel and Whillier, 1958)  U (W cb Di h  
L fi 
was used. The thermal efficiency (th) of the
conventional flat plate solar collector can be Therefore, the efficiency factor F can be calcu-
calculated using the Equation 2 below (Duffie lated using Equation 12:
and Beckman, 1991):
tanh M  W- D 
 2
F =
Qu  W- D 
 th  G 2 M  2 
7

Using Equation 2, the useful heat collected (Qu) M= UL
by the water in terms of its temperature rise can
be explored further using Equation 3 (Duffie and Where  Kabs Labs  (K pv  Lpv )
Beckman, 1991):
The useful heat gain of the solar collector can be
 3 calculated by rearranging Equation 7, and the
thermal efficiency of the collector can be
Qu = mC p (To  Ti ) expressed using Equation 8 (Vokas et al., 2006):

The difference between thermal heat losses and  th= FR ( )  FRU L ( Ti  Ta ) 8
the absorber solar radiation was identified using GT
the Hottel–Whillier equations(Hottel and
Whillier, 1955), then the energy balance equa- The temperature-dependent electrical efficiency
tion for the collector is identify as in Equation 3: of the PV panel (el) is expressed as follows
(Tiwari and Sodha, 2006):
Qu  AcFRS  UL (Ti  Ta ) 4
  el=r 1  (Tpm  Tr )
From Equation 4, the solar irradiance absorbed 9
by a collector per unit area of absorber S is equal
to the difference between the incident of solar Where el is the electrical efficiency, r is the
irradiances and optical loses. The S can be reference efficiency of the PV panel (r = 0.14), β
identified using Equation 4.1: is the temperature coefficient (°C0.0045 °C-1),
Tpm is the temperature of the solar cells (K), and
S  ( )PV GT 4.1 Tr is the reference temperature.

The heat removal efficiency factor (FR) can be 3.3 Design Configurations of the Absorber
calculated as in Equation 5 (Duffie and Beckman,
1991): As the PV cells in the PV module are exposed to
the sun, they generate electricity while
absorbing heat, causing the absorber to increase
its temperature. During this time, the water fluid

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