Heat transfer characteristics of concave and convex curved vortex generators in the channel of plate heat exchanger under laminar flow

Abstract

Abstract The geometric shape of vortex generator (VG) is an important contributory factor to heat transfer enhancement. In this paper, concave and convex curved delta winglet VGs in a channel of plate heat exchanger under laminar flow are studied and compared with the normal plane delta winglet VG to optimize the shape of VGs. The effects of the central angles ranging between 10° and 80° and the angles of attack (20°, 30°, 40°) of the concave and convex curved delta winglet VGs on the characteristics of heat transfer and pressure loss are presented for different Reynolds number (Re) ranging from 200 to 1400. The results showed that Nusselt number (Nu) increases with the increase in the central angle of the concave curved delta winglet VG, while Nu decreases with the increase in the central angle of the convex curved delta winglet VG. Comparing with the normal plane VG, the concave curved delta winglet VG is beneficial to heat transfer enhancement, while the convex curved delta winglet VG is disadvantageous to heat transfer enhancement. Optimum values of the central angle and the angle of attack exist for the concave curved delta winglet VG in terms of the best heat transfer performance. The largest values of Nu and surface goodness factor (JF) for the concave curved VG are larger by 19.7% and 11.35% respectively than those for the convex curved delta winglet VG in the studied range of parameters. Correlation equations for both Nu and friction factor (f) as a function of Re, central angle and angle of attack are presented for both concave and convex curved delta winglet VGs.