| dc.description.abstract | Photovoltaic cells convert, depending on the cell type, 6-18% of the incoming solar
radiation into electricity with a higher percentage converted into heat. The heat in turn
affects the cell temperature which has direct impact on its efficiency. In literature, both
water and air have been used for PV cooling through a thermal unit attached to the back of
the module yielding a photovoltaic-thermal (PVT) system. But the use of water requires
more extensive modifications to prevent leakage and corrosion. Hence, an air channel
operating on forced convection that would substantially improve the heat transfer aspects
was chosen.
This study investigates the performance of a low-cost heat-extraction improvement
in the channel of a PVT air system that achieves higher thermal output and PV cooling
while keeping the electrical efficiency at acceptable level. This study presents the use of a
"helical insert" along the air channel as heat transfer augmentation that improves the PVT
system's overall performance. Based on energy balance of each component of PVT system,
an analytical expression for the temperature of the PV module, back wall and the outlet air
has been derived. The developed model was first validated with the experimental data
obtained by researchers. By confirming a good agreement with the experimental data,
simulations were carried out to optimize various operating parameters, like the channel
hydraulics, air mass flow rate, twist angle of helical insert and number of inserts. Then the
steady-state thermal efficiency of the modified system equipped with helical insert is
compared with those of typical PVT air systems. The modification results in a substantial increase m the overall thermal and electrical efficiencies to about 66.5% and 13.5%,
respectively. Hence, these techniques would positively impact the applications of PV
systems, more specifically Building Integrated Photovoltaics (BIPV). | en_US |
