Experimental investigation of the performance of a double-pass unglazed transpired solar air heater

Abstract

This study presents an experimental investigation of the performance of a double-pass unglazed transpired solar air heater. The performance of the solar air heater was evaluated from the experimental data by energy and exergy analyses. The average thermal efficiency of the solar air heater was found to be 16.9 and 20.6% at the air flow rate of 0.015 and 0.019 kg/s, respectively. The average exergy efficiency was found to be 0.49 and 0.57% at the air flow rate of 0.015 and 0.019 kg/s, respectively. The thermal effectiveness of the heater was 66.6 and 67.1% at the air flow rate of 0.015 and 0.019 kg/s, respectively. The energy and exergy efficiencies and the thermal effectiveness increased with increase in the mass flow rate of air. The performance of this solar air heater is comparable to the conventional glazed solar air heater although it does not have any cover plate.