Numerical investigation of heat transfer and pressure loss of flow through a heated plate mounted by perforated concave rectangular winglet vortex generators in a channel

Abstract

The low thermal conductivity of air in fin-and-tube heat exchangers causes high thermal resistance of the air side and results in a low heat transfer rate. This heat transfer rate on the air side can be improved by increasing the heat transfer coefficient. One way to increase the heat transfer coefficient on the air side is to use a vortex generator (VG), which can generate longitudinal vortex (LV) increasing fluid mixing. Therefore, this study aims to numerically analyze heat transfer characteristics and pressure drop of airflow through a heated plate by installing VG in a rectangular channel. Vortex generators (VGs) used in numerical modeling are rectangular winglet pairs (RWPs) and concave rectangular winglet pairs (CRWPs) with 30 attack angle. The number of pairs of VG is varied by one, two, and three with/without holes. The velocity of airflow varies in the range of 0.4-2.0 m/s at intervals of 0.2 m/s. The simulation results show that in the configuration of the three pairs of VG, the decrease in the convection heat transfer coefficient in the case of the perforated CRWP is 3.98% of the CRWP without holes at a velocity of 2.0 m/s. While in the configuration of three pairs of perforated RWP VGs, the decrease in convection heat transfer coefficient is 5.87% from RWP without holes at a velocity of 2.0 m/s. In the configuration of three pairs of perforated VGs at the highest velocity, the decrease in pressure drop in the CRWP and RWP cases is 30.73% and 13.87% of the VGs without holes, respectively.