Experimental Analysis on Thermal Performance of a Solar Air Heater at Different Angular Positions

Heat transfer enhancement and hence performance of solar air heaters can be improved by absorbing maximum amount of solar insolation. Absorption rate in solar air heater is increased when it is oriented all the time in perpendicular direction to solar insolation. Hence, inclination of solar air heater along with other geometrical and operating parameters plays an important role to decide its thermal performance. In the present work, a double-pass packed bed solar air heater is experimentally tested to know the effect of its inclination to solar insolation on its thermal performance. Experiments are conducted at different mass flow rate of air in the range of 0.038–0.0508 kg/s and at different inclination of solar air heater in the range of 5°–25° to the horizontal surface. It was found that efficiency of solar air heater is lower at 5° and 10° inclinations for all mass flow rates of air. Efficiency increased and reaches to its maximum value for 15° and 20° inclinations of the solar air heater, and it decreases with further increase in inclination to 25° at all mass flow rates of air.