Numerical evaluation of thermal hydraulic performance in fin-and-tube heat exchangers with various vortex generator geometries arranged in common-flow-down or common-flow-up

Abstract

Vortex generator as secondary flow enhancement technique has captured the attention of many researchers recently to augment the performance of the fin-and-tube heat exchanger (FTHE). There are various vortex generator parameters that influence the thermal and hydraulic performance in the FTHE such as the geometry and arrangement. In this study, the effect of different vortex generator geometries and arrangements was investigated using numerical simulation method. There are three vortex generator geometries studied including rectangular winglet (RWVG), delta winglet (DWVG), and trapezoidal winglet (TWVG). The vortex generators were placed behind tubes either in common flow down (CFD) or common flow up (CFU) arrangement. The introduction of vortex generators behind tubes resulted in heat transfer augmentation but comes together with higher pressure drop penalty. Further analysis on the thermal performance has found that TWVG in CFU arrangement almost obtained similar thermal performance factor with respect to the baseline case at Reynolds number 500 and 600. However, the thermal performance factor for TWVG in CFU arrangement decreases as the Reynolds number further increased. For other vortex generator cases, lesser thermal performance factor was found as compared to the baseline case.