Heat transfer enhancement using different types of vortex generators (VGs): A review on experimental and numerical activities

This paper presents a comprehensive review on heat transfer augmentation and pressure loss reduction of compact heat exchanger (CHXs) by using interrupted surfaces in the form of vortex generators (VGs). The influence of type, shape, and design and attack angle of VGs on enhancement of heat transfer rate and pressure loss are widely discussed. The sole objective of this review is to gather major thermodynamic features of CHXs presented by researchers through both experimental and numerical investigation for innovative designing purpose of heat exchangers. We have evaluated the effects of different types of vortex generators, their arrangement, location, attack angles and height on heat transfer and friction characteristics of heat exchangers. It was noticed that longitudinal vortices induced by vortex generators leads to the reduction of wake region behind tubes, augmentation of turbulence intensity and higher flow mixing. However, the intensity and strength of these vortices is strictly dependent on Reynold number. Delta winglet type vortex generators provide better heat transfer performance than rectangular winglet type vortex generators. Location of these winglets is quite suitable in downstream region than upstream region. Moreover, flow visualization techniques are discussed to analyze the vortex formation due to VGs at microscopic level.