Matrix solar air heaters – A review

Abstract

Improvement of thermal performance of a solar air heater can be obtained by enhancing the rate of heat transfer. Thermal efficiency of matrix solar air heater is higher in comparison to conventional type. Number of studies has been reported in the literature on the performance of matrix air heater with different material packing and elaborated various parameters such as design; heat transfer enhancement, flow phenomenon and pressure drop in the duct. Majority of the studies revealed an increase in the thermal efficiency for matrix collector as compared to conventional plane solar air heater. This review paper presents an extensive study of the research carried out on matrix solar air heater. Based on literature review, it is concluded that the solar air heaters performed well when packed with porous medium and this is due to the geometrical parameters of porous material. In addition double pass porous bed solar air heaters performed better than single pass. Various types of matrix materials used in the literature and correlations developed for heat transfer and friction factor by different researchers have been presented. Much attention has been devoted in this paper to portrait the development of various types of solar air heaters over the years. The merits and demerits of different models evolved by many researchers have been critically analyzed. Finding in a nut shell is that the drawbacks associated with conventional nonporous solar air heaters such as high heat loss to the ambient, decreased convective heat flow from plate to air, etc. can be overcome by the use of an effective design of porous bed solar air heater.