Heat Transfer Augmentation in Fin and Tube Heat Exchanger Embedded with Vortex Generators

Abstract

The aim of this study is to investigate experimentally turbulent flow around tube by using multi–shapes of winglet vortex generators mounted behind the tube at different angles of attack, in order to investigate the effect of winglet on heat transfer and pressure drop of fin and tube heat exchanger placed inside a rectangular duct with Reynolds numbers (Re) ranging from (19000) to (49000). Fin-and-tube heat exchangers are frequently employed in a variety of industries, including power systems and air conditioning. The heating element inside the tube receives a power source ranging from (10W) to (40W). In these studies, vortex generators of the triangular and rectangular types are installed at various angles of attack (45° and 60°) on the fin surface behind the tube. The findings demonstrate that depending on the form and angle of attack of the winglets, utilizing winglet pairs has an impact on the heat transfer coefficient and friction factor relative to other designs. With increasing angle of attack, the friction factor and heat transfer coefficient rise. The optimal design for improving heat transfer is the rectangular type vortex generator, whereas the triangular type produces the least amount of heat transfer. The rectangular style of duct has the greatest pressure drop. For rectangular and triangular heat exchangers, respectively, the average Nusselt number is increased by 19% and 12%. The average Nusselt number of a fin and tube heat exchanger is increased by (16.7-17.8%) % for the rectangular type and by (9.3-10.6%) % for the triangular type at an angle of attack (β=60°) compared to (without winglet) case for Reynolds number ranging between (19000-49000), where the triangle type gives the least amount of heat transfer compared to other shapes.