Heat Transfer Augmentation of Compact Plate Fin Heat Exchanger Using Modified Fin Surfaces 2018-28-0012
A numerical study of three-dimensional flow and heat transfer of a rectangular plain with built-in delta winglet type longitudinal vortex generators is carried out in order to enhance the convective heat transfer at the air side of the fin with minimum penalty on pressure drop. Longitudinal vortices develop along the side edge of the delta winglets due to the pressure difference between the front surface (facing the flow) and back surface. These vortices interact with thermal boundary layer and produce a three dimensional swirling flow that mixes near wall fluid with the midstream. Thus the thermal boundary layer is disrupted and heat transfer is enhanced. The efficiency of the delta winglet vortex generators widely varies depending on their size and shape, as well as the locations where they are implemented. In the present study, the longitudinal vortices have been created by the delta-winglet type vortex generators in common-flow-down configuration. The numerical investigations are carried out for four different angles of attack of the winglet (15°, 25°, 35° and 45°) and different Reynolds numbers (1000 to 4000) for common flow down configuration. It is observed from the simulation results among different angles of attack of the VGs, the performance of delta winglet pair at 25° is best in terms of heat transfer at all the Reynolds number considered in the present study.