Thermal Analysis of Double-Pass Solar Air Collector with Different Materials of Absorber Plate and Different Dimensions of Air Channels

Numerical simulation for thermal performance of double-pass solar air heater with counter flow was investigated in the present study. Thermal efficiency of double-pass solar air collector was estimated for different materials of absorber surface and different dimensions of upper and lower air channels. The optimum thermal efficiency of double-pass solar air heater were identified for a wide range of the solar radiation intensities (600-1000 W/m2) and mass flow rates (0.01-0.10 kg/s). A code of MATLAB program was built to simulate the mathematical model of double-pass solar air heater. The results showed that the thermal efficiency of double-pass solar air collector of Velesat black plastic absorber plate was better than of Aluminum absorber plate. A comparison between the thermal efficiency of double-pass solar air collector of Velesat black plastic absorber plate and Aluminum absorber plate was analyzed and discussed. A validation of MATLAB code was checked via a comparison with the previous literature. Generally, the thermal efficiency was increased when the mass flow rates and solar radiation intensities increased. The optimum thermal efficiency was occurred at the upper air channel (D1=0.04m), lower air channel (D2=0.08m) for the Velesat black plastic absorber plate for solar radiation intensity (I=1000 W/m2) and mass flow rate (m. =0.10 kg/s).