Solar air pre-heater design, Vol. II

Both the heat transfer coefficient and friction factor are found to be strong functions of bed parameters. The effective efficiency is a useful parameter to take into account the effect of enhanced useful heat gain and friction losses. By maximizing the effective efficiency, the bed parameters can be optimized with regards to high useful heat gain and low friction losses. In the present work, solar air heaters packed with wire mesh matrix have been optimized for maximum effective efficiency with respect to bed parameters i.e. number of layers, bed porosity and pitch to diameter ratio of wire mesh. A computer program had been developed for simulation for optimal design of packed bed solar air heaters. The results of optimization are presented in the form of design plots for packed bed solar air heaters in terms of bed parameters. These plots can be used for selecting the optimal bed parameters and predicting the thermal efficiency of these solar air heaters for a given temperature rise and insolation.