Optimization of H-type finned tube heat exchangers with combinations of longitudinal vortex generator, dimples/protrusions and grooves by Taguchi method

Abstract

In this paper, some novel structures aimed to optimize the airside performance of H-type finned tube heat exchangers, such as longitudinal vortex generators, dimples/protrusions and grooves, are examined numerically. The effects of geometric parameters on the heat transfer, flow resistance and comprehensive thermal–hydraulic performances are investigated by means of Taguchi method. The optimum configuration of compound designs is determined on the basis of the optimizations of these structures. According to the results, for longitudinal vortex generators, dimples/protrusions and grooves, the heat transfer characteristics are significantly affected by the winglet type, vertical distance and groove diameter while the attack angle, dimple depth and groove type have prominent impacts on the flow resistance characteristics. The winglet type, vertical distance and groove number make the most contributions to the comprehensive thermal–hydraulic performance, respectively. In compound designs, the longitudinal vortex generator plays the most important role in the performance of heat exchangers. The comprehensive thermal–hydraulic characteristic of the optimal compound design exerts the improvements of 0.9–23.8%, 24.5–57.1% and 8.3–37.5% than those of LVGs, dimples/protrusions and grooves, respectively, when Reynolds number ranges from 4650 to 28,300. The enhancement of 4.5–16.6% can be achieved compared with the case built based on references.