SIMULATION OF A COUNTER FLOW SOLAR AIR HEATER

Abstract

The intent of the present study is to study the behavior of counter flow solar air heaters and to compare their performance with the conventional solar air heaters under different set of conditions, obtained by changing the various governing parameters like air mass flow rate, inlet air temperature, spacing between top cover and absorber plate and intensity of solar radiation. In the present study, different type of solar air heaters with the absorber plate fixed at the bottom are considered and the air is forced to flow over the absorber plate instead of below it so as to reduce the major heat losses from the top glass cover and thereby increasing the thermal efficiency of the collector. Four types of solar air heaters have been taken into consideration viz, the single cover conventional, the double cover conventional, the counter flow with and without porous matrix solar air heaters. The problem has been solved by the Finite Difference Method (FDM). It has been found that the counter flow solar air heater is more efficient than the conventional solar air heaters. The drawbacks of the conventional air heaters are identified. The use of counter flow heater increases thermal efficiency by as much as 10%. The thermal efficiency of counter flow solar air heater is further increased by the use of porous matrix by about 8%. iii