A comprehensive review on vortex generator supported heat transfer augmentation techniques in heat exchangers

The use of passive heat transfer enhancement strategies to improve heat transfer performance in heat exchanger has received a lot of attention. In this paper, passive heat transfer enhancement methods utilizing vortex generation in the flow field have been discussed in detail. Three classic techniques for improving passive heat transfer in heat exchangers have been identified in the literature: boundary layer deformation, swirl formation, and flow destabilization. The longitudinal vortices generated by vortex generators have been found to reduce the wake region behind tubes, thus increasing turbulence strength and flow mixing. This review takes into account the effect of geometrical variations of vortex generators on thermo-fluid performance. Delta winglet vortex generators outperform rectangle-winglet vortex generators in terms of heat transfer performance. However, using hole-type rectangular winglets has shown promising results with more than 16% enhancement in thermo-fluid performance. Among several winglet angles examined by various researchers, the attack angle in the range of 30 degrees-45 degrees has resulted in optimum performance. Some variations of rectangular winglets such as wavy winglets have been reported to enhance the overall thermo-fluid performance by 8-16%. This paper provides insight into different experimental and numerical techniques for the enhancement of thermo-fluid performance of cross-flow heat exchangers. This review article can be very helpful to industrial and academic researchers working in the area of compact and efficient heat exchanger design with enhanced thermo-fluid performance.