Application and optimization of fin-and-tube heat exchangers with longitudinal vortex generators

The longitudinal vortex generator (LVG) can significantly enhance the heat transfer in fin-and-tube heat exchangers with a moderate pressure loss penalty. A 3-D numerical simulation was employed to investigate the flow and heat transfer characteristics of fin-and-tube heat exchangers. The optimizations for critical parameters of vortex generator, i.e., the attack angle, number and position of LVG, were performed. The results show that the enhancement of heat transfer on the airside can surpass the increase of the pressure drop in a fin-and-tube exchanger with three pairs of rectangular winglets and an attack angle of 15°. Compared with the conventional configuration, the heat transfer coefficient of the enhanced configuration is improved by 71.3%-87.6% while the pressure loss is increased by 54.4%-72%. The average heat transfer coefficient on the airside increases with the number of vortex generator, but the local heat transfer is affected little by the number of vortex generator after the fifth tube. Compared with the inline arrangement of vortex generators, the staggered arrangement of vortex generators can further reduce the pressure loss penalty while maintain the enhanced heat transfer.