Numerical study of flow and heat transfer enhancement of circular tube bank fin heat exchanger with curved delta-winglet vortex generators

Abstract

To reduce the peeling wake area and generate longitudinal vortices at the rear of circular tube employed in tube bank fin heat exchanger, a new fin pattern with curved delta-winglet vortex generators (CDWVGs) punched on fin surface was proposed. A conjugate heat transfer numerical method is employed to investigate the heat transfer performance of the staggered circular tube bank fin heat exchanger with CDWVGs. Their radial and circumferential locations, height and length are the main parameters to investigate. CDWVGs can not only guide the flow to reduce the size of the wake region, but also generate secondary flow to enhance heat transfer of the fin surface. CDWVGs can effectively enhance heat transfer under either identical pumping power or identical mass flow rate constrains. The optimal geometry parameters and position parameters of CDWVGs are found for the majority of studied Re. If the effect of the main working, geometry and position parameters on heat transfer is cast into the relationship between the secondary flow intensity and Nusslet number, the intensity of secondary flow mainly determines the heat transfer ability of the fin surface.