An Experimental Investigation to Check the Overall Performance of a Packed Bed Solar Air Heater

An experimental investigation of thermohydraulic performance characteristics of a packed bed solar air heater is done in the present work. The packed bed is generally used to enhance the heat transfer area, increase the turbulence in the flow and for the storage of thermal energy. The experimental investigation has been carried out on a low porosity packed bed solar air heater. The investigation covers a particular range of design and operating parameters. Design parameters take account of the equivalent diameter of packing material (1.55 mm), packing density (250 g per 0.075 m3) and colour of the packed bed material (Black) while the operating parameters take account of the mass flow rate ranging from 0.01 to 0.04 kg/s. It is observed that the efficiency of the air heater increases with increase in mass flow rate. It is also found that the impact on the overall efficiency due to frictional loss is much less in a low porosity packed bed solar air heater.