On the Use of Longitudinal Fins to Enhance the Performance in Rectangular Duct of Solar Air Heaters—A Review

Abstract

The objective of the present article is to present a detailed review of the research carried out on the use of extended surface in the form of longitudinal fins, with its different shapes, geometries, and attachments on solar air heater (SAH), to improve the thermal performance of conventional SAH duct. The use of extended surface in the scheme of fins placed longitudinally along the air-flow path on the absorber or bottom plate surfaces is an effective method to augment the performance of SAH duct. Various studies have been carried out through employing longitudinal fins for the enhancement in thermal performance of simple SAH duct. Finally, all the details of the literature as a summary, i.e., about fin geometries, systems, and operating parameters for analysis, are compiled together and well tabulated. The investigators used correlations for heat transfer, and friction factor also has been classified and presented in a relevant form in the present article. Finally, an attempt has been made to compare the performances of different finned SAHs by using correlations.