ThermalPerformance of Rhombus Shape Roughened SolarAir Heater-Analysis

Solar air heaters have been used for many applications requiring low to medium grade thermal energy, like, space heating and cooling, agricultural drying, timber seasoning, mainly due to their tow manufacturing cost, simple design, operating and maintenance. Their usefulness as also the quantitative energy collection has been limited because of lower thermal efficiencies primarily as a result of lower convective heat transfer coefficient between the absorber plate and air leading to higher plate temperature and greater thermal losses. Several designs for the enhancement of heat transfer coefficient and hence the improvement of thermal performance of solar air heaters have been proposed and investigated by a number of investigators. Such designs are honeycomb collector, corrugated absorber, V- shape absorber, extended surfaces absorber, double-exposure collector, two pass collector, packing of porous material in air flow channel i.e. packed bed absorbers and use of artificial roughness on the absorber plate. The artificial roughness has been used as an effective means for improvement of thermal performance of solar air heaters.