The combined effect of nanofluid and reflective mirrors on the performance of PV/Thermal solar collector

Abstract

A photovoltaic thermal (PV/T) solar collector is a system which is capable of producing both electricity and thermal energy;however this technology still needs more studies. In this paper, a mathematical model was presented to study the performance of a PV/Thermal collector by using the upper and lower reflectors with the presence of glass cover. Water and nanofluids (AL2O3-H2O) were used as cooling medium. A computer program was proposed to calculate the amount of solar radiation reflected on the reflected mirrors and then absorbed by the hybrid collector and study the effect of Nano-fluid on the performance of the system. Solar radiation absorbed by the collector can be increased using the upper and lower reflectors to 1138 W/m2 while it can reach 950 W/m2 with the upper reflector and 746 W/m2 with the lower reflector. It was noticed that when using reflective mirrors, the outlet water temperature increased by 21.7 %. Meanwhile, the outlet water temperature increased by 0.44% when nanofluid was used as a cooling medium. The average of daily thermal efficiency as a result of using two reflectors without nanofluid was 62.1%, while the thermal efficiency was 59.735 % without using any reflector, meaning a positive effect of using reflectors on the thermal efficiency. The electrical efficiency reduced with the existence of the reflective mirrors, whereas the daily average of the total electrical efficiency without the reflective mirror and using the nanofluid was (14.6 %), while with a reflective mirror and using nanofluid, the daily average was (13.67 %).