Integration of winglet type vortex generators in finned-tube heat exchangers for a sizeable capacity augmentation

Abstract

Compact size of the heat exchange module is an important design consideration in majority of the thermal management systems. Using winglet type vortex generators, a sizeable improvement in the compactness of a widely used finned-tube array is attempted through this study. Since the degree of thermal augmentation changes with the generators’ position, around the tubes, this 3D comprehensive computational investigation aims to develop phenomenological correlations for the positional optimization, which are applicable over a wide range of operating conditions. Besides, this article is dedicated to understanding different aspects of the augmentation mechanism, including the tube-wake management and the performance improvement caused by the best design(s). Based on a parametric investigation, designs that are best suited for obtaining a sizeable performance augmentation of the system are identified. Furthermore, a critical assessment of the best designs is carried out to evaluate their impact on the heat transfer from wake-affected surfaces, both fins and tubes. It is encouraging to observe that the wake-affected surfaces also experience sizeable thermal augmentation, which increases further with the Reynolds number. While the total fin surface experiences a highest Colburn j-factor augmentation of 53.6%, the wake-affected fin undergoes 205.1% rise. An evident manifestation of the augmented Colburn j-factor is the reformed temperature distribution, which bears lower values all over the fins.