PERFORMANCE ANALYSIS OF DOUBLE PASS SOLAR AIR HEATER

Abstract

Solar energy is the most important among renewable energy sources due to its quantitative abundance, its capacity to overcome the energy crisis and environmental threat caused by the continuous use of fossil fuels on a very large scale. The heart of any solar energy related system is solar collector. Conventional solar air collectors have poor thermal efficiency primarily due to high heat losses and low convective heat transfer coefficient between the absorber plate and flowing air stream, leading to higher absorber plate temperature and greater thermal losses. Attempts have been made to improve the thermal performance of conventional solar air collectors by employing various designs and flow arrangements. The double pass counter flow arrangement with porous material in the second air passage is one of the important design improvements that have been proposed to achieve the objective of improved thermal performance. The major reason of interest in porous packing includes its high effective heat transfer area per unit volume of packed duct resulting in high heat transfer capability. Also solar radiations are progressively absorbed by the layers of wire mesh and the remaining radiations are absorbed by the absorber plate. Two, cases have been investigated in the present work one for the wire mesh layer (n=1) one and another for wire mesh layers (n=3) three and effect of inlet air temperature are also considered. For matrix material maximum thermal efficiency for three wire meshes has been found (68.6%), with one wire meshes 60.6%. and without matrix material it is found 56.4%. The effect of deferent parameter such as mass flow rate, porosity, inlet air temperature, solar radiation intensity has been studied.