COMPARISON STUDY OF AIR an‎d THERMAL OIL APPLICATION IN A SOLAR CAVITY RECEIVER

Nowadays, solar dish collector with a cavity receiver is accounted as an efficient and compact system for converting solar radiation energy into thermal energy. All of the incoming solar irradiation to the dish aperture area, is concentrated at the dish focal point where the solar receiver is located. In the current study, the thermal performance of the dish collector with a rectangular cavity receiver was evaluated. Air and thermal oil were examined as the solar working fluids. The performance of the solar dish collector was evaluated at different values of the mass flow rate ranging from 0.002 to 0.06 kg/s as well as different solar irradiation ranging from 600 to 1200 W/m2 . The results revealed that the collector efficiency improved with increasing the mass flow rate and solar irradiation. The thermal performance of the solar dish collector improved with application of the thermal oil as the solar working fluid compared to the air in the investigated solar system. The results indicated the higher cavity surface temperature could be achieved by using air as the solar working fluid compared to the thermal oil.