Exergetic performance assesment of a downward solar air heater with impinging air jets - An experimental study

Abstract

The main objective of the present study is to perform an in-depth exergetic analysis on a downward solar air heater (SAHRR) in two configurations: one incorporating impinging air jets and the other without it utilizing an indoor experimental setup. In the present study, the exergy efficiency is calculated based on the rates of exergy losses to evaluate separately the exergy losses, providing insights into the specific terms that contribute to the highest rates of exergy deterioration for the given SAHRR. This investigation is performed to understand how various parameters, such as mass flow rate(m) and geometric parameters influences the thermal performance of SAHRR. Thermal performance was assessed experimentally by considering several parameters, including average Nusselt number, first law thermal efficiency, thermohydraulic efficiency, and exergy efficiency. The maximum thermohydraulic efficiency of 84.86% was obtained at m equals 0.06 kg/s with geometric parameters of relative jet spacing (H1/HD) of 0.5, relative jet Diameter (DJ/DH) of 0.057. From the investigation, it could be concluded that the predominant origin of exergy loss in both SAHRR configurations is attributed to the exergy losses resulting from the temperature difference between the sun and the SAHRR surface, which constitutes 70% of the overall exergy losses.