EFFECT OF THERMO-PHYSICAL PROPERTIES OF BED MATERIAL ON THE PERFORMANCE OF PACKED BED SOLAR COLLECTORS

Abstract

The conventional solar air collector have a low efficiency due to low heat transfer coefficient between plate and air. A number of methods have been used or enhancement of efficiency. The use of porous beds in the collector duct has been shown to have certain specific advantages over the other methods. The heat transfer capability between absorber ►materials and the air is considerably higher in case of porous beds due to high heat transfer area density and heat transfer coefficient. In order to analyse the thermal performance and to study the effect of system and operating parameters on the thermal performance of such systems. heat transfer equations based on heat and fluid flow for a homogeneous, gray non-scattering, semi transparent and conducting bed and operating under quasi-steady state conditions, have been developed. Finite difference solution algorithm has been developed for obtaining numerical solution of the governing equations for energy transfer. The results comprising temperature distributions, outlet temperature of air and the thermal efficiency have been computed. Results show that the enhancement of performance of pact ed bed collector is a strong function of bed and operating parameters it shows a need for the judicious choice of these parameters to obtain maximum benefit from such a system.