Plate Temperature and Heat Transfer Characteristics of Three sides Roughened and Boosted Solar Air Heaters

Higher value of intensity of radiation on absorber plate of solar air heaters and effective heat removal from the plate by the carrier fluid, air, enhances thermal performance of solar air heaters. The paper deals with the experimental results of enhancing the intensity of radiation by means of booster mirrors and that of heat transfer by means of providing artificial roughness on the air flow side of the absorber plate. An enhancement in radiation of about 40% have been found over the normal incident radiation by means of booster mirrors leading to 7% to 15% higher rate of heat collection. The thermal performance parameters FR and F' have been found to increase in the range of 90% to 130% and 92% to 135% respectively in comparison to those of smooth solar air heaters without booster mirrors and in the range of 10% to 15% in comparison to roughened solar air heater without booster mirrors, within the range of the parameters investigated.