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Thermal performance of packed bed solar air heater

Packed beds are generally used for storage of thermal energy from solar air heaters. In this paper experimental study has been conducted on a porous packed bed solar air heater using iron chips as packing material. The parameters used for study include equivalent diameter of packing material ( iron chips) 1.51 mm, porosity 0.652 and 0.816, mass flow rate from 0.014 - 0.0365 kg/s and packing Reynolds number range from 250-1100. The effect of air massflow rates and bed porosity on the thermal performance of packed bed solar air heaters are investigated. It is seen that heat transfer coefficient and friction factor are strong functions of geometrical parameters of the porous packed bed. The results of a packed bed solar air heater shows a substantial enhancement in the thermal performance as compared to the conventional collector also a decrease in porosity increases the volumetric heat transfer coefficient.