Heat transfer characteristics of a circular tube bank fin heat exchanger with fins punched curve rectangular vortex generators in the wake regions of the tubes

Abstract

Vortex generators (VGs) applied on the fin surfaces of circular tube bank fin heat exchangers can increase the intensity of secondary flow and reduce the size of wake regions behind circular tubes. In this study, a new type of the fin is reported, on which curve rectangular vortex generators (CRVGs) are punched. A numerical method is used to investigate the fluid flow and heat transfer characteristics of the fin. The average Nusselt number, friction factor and secondary flow intensity are larger than that of the reference plain fin at different Re, respectively. The local Nusselt number on the fin surface contacting with the wake region increases significantly. The circumferential position, the radial position, the base arc length and height of VGs and the fin spacing are the main parameters investigated to disclose their effect on the heat transfer performance of the fin. When the leading edge of VGs is located in the transversal axis of the tube, the diameter of the base arc length of VGs is large, the height of VGs is about 0.8 times of the fin spacing, heat transfer performance is optimal, and the base arc length of VGs is about 3.8 times of the optimal height of VGs, better heat transfer performance can be obtained. For working condition of different Reynolds number, when the ratio of the fin spacing to the tube outer diameter is 0.239, better heat transfer performance is obtained.