OPTIMIZATION OF BED PARAMETERS FOR PACKED BED, SOLAR ENERGY COLLECTION SYSTEM

Abstract

Solar air heaters are generally used for low to moderate temperature energy requirements. These systems are cheap and easy to maintain, but suffer from the disadvantage of low thermal efficiency. Several methods have been proposed for the enhancement of the efficiency of such collectors. Use of porous packing material in the collector duct is one of the methods. However, this enhanced efficiency is accompanied by substantial increase in pressure loss, which results in higher running cost of the system. So, the solar energy collection system should be optimized in such a way that it will give energy with minimum cost. In this work two types of packed bed collectors, one with wire mesh screen matrix bed and other with pebble bed were optimized on the basis of minimum cost of unit energy delivered. Tables for optimum values of bed parameters namely, number of layers, porosity, pitch to wire diameter ratio and pebble diameter has been prepared on the basis of minimum cost. These tables and design methodology can be used as a guideline to a designer for selecting the optimum values of bed parameters for a given temperature rise parameter and average insolation.