Performance evaluation of plastic solar air heater with different cross sectional configuration

Solar air heaters, SAHs, represent the primary component of solar energy usage systems. The SAHs are able to absorb the solar energy and convert it into thermal energy at the absorbing surface, and then transfer the thermal energy to an air flowing through the SAH. In this work, an experimental investigation was performed on three SAHs with different cross sectional shape to find the best configuration. The shapes are circular, semi-circular and half-circle plus isosceles triangle. All SAHs have an identical absorber with a half-circle shape. The mass flow rate of air was changed from 0.05 to 0.25 kg/s. Results indicated that the highest efficiencies were accomplished for the circular configuration and reached to about 80% at a mass flow rate of 0.18 kg/s. On the other hand, for the same conditions, the thermal efficiency reached about 64% and 48% for half-circle plus isosceles triangle and semi-circular shapes, respectively.