Temperature coefficient ( ββ rr ) Reference PV panel temperature
0.0045 /° C 298.15 K
Glass solar transmittance 92 % Absorber tube Inner diameter ( DD ii ) 0.008 m
Thickness ( δδ tt )
0.0012 m Specific heat ( CC tt ) 903 J /( kg . K )
Density ( ρρ tt )
2702 kg / m3 No . of tubes 9 Tube spacing Material
0.11 m Copper
Back panel |
Density ( ρρ bb ) |
20 kg / m3 |
|
Specific heat ( CC bb ) |
670 J /( kg . K ) |
|
Thermal conductivity ( KK bb ) |
0.034 W /( m . K ) |
Fluids used |
Water & air |
‐ |
2.4 . Model Validation
The proposed mathematical model of PV / T system has been validated using air‐type heat exchanger from the dual‐fluid heat exchanger . The selection of air heat exchanger can be explained by the fact that from the previously published studies authors found only single‐fluid PV / T system that has used glass to glass PV protection . For the purpose of comparison between numerical and experimental results , identical physical dimensions and operating conditions have been used in the mathematical model similar as presented by Kim et al . [ 20 ], during the experimentation . Figure 2 shows the PV temperatures derived from model and measured by Kim et al . [ 20 ]. The depicted PV temperatures are accordance with the variable air flow rates . It is obvious the PV temperature decreases with increasing the air flow rate but the important point is numerical results have good agreement with experimental data . In fact , the maximum difference between numerical and measured data is within acceptable range . It can be deduced from the aforementioned comparison that the proposed model can be employed for performance prediction of a glass to glass PV / T system .
Performance Evaluation of Photovoltaic / Thermal ( PV / T ) System Using Different Design Configurations 376