Experimental assessment of double-pass solar air heater by incorporating perforated baffles and solar water heating system

Abstract

An investigation on a solar combi-system that serves the dual purpose of supplying increased temperature air for Solar Air Heater (SAH) based applications and hot water for domestic applications is presented in the article. To achieve the objective of the solar combi-system, two identical double-pass SAHs were fabricated: one without augmentation, while the other with an augmentation of vertical plate perforated baffles on the absorber plate and the pipe carrying hot water over the bottom plate. Experiments for the upward and downward flow of air were carried out for three consecutive days in each case to investigate the thermal performance of both SAHs. Compared to the conventional SAH, daily average outlet air temperature, daily average heat gain received by air, daily average efficiency, heat transfer coefficient (average), and Nusselt number (average) were higher by 6.48%, 17.10%, 17.24%, 5.77%, and 5.20% for the upward flow of air in the augmented SAH, respectively. Whereas increment of 8.59%, 21.46%, 21.87%, 27.28%, and 26.68% was obtained in respective parameter for the downward flow of air in the augmented SAH. The thermal performance of augmented SAH was found superior compare to that of conventional SAH in the case of the downward flow of air.