Numerical investigation of the flow and heat transfer in tube with a concave generator

Abstract

The installation of a vortex generator (VG) on the heat transfer surface is a common enhanced heat transfer technology. The vortex generator is used to induce the vortex to destroy the flow boundary layer, reduce the heat transfer resistance, and improve the efficiency of the heat exchange equipment. In the present study, a numerical investigation is performed to compare the heat transfer capacity of concave VG, convex VG and trapezoidal VG. Since the position of the vortex affects the heat transfer and the vortex generated by concave VG is closer to the wall, concave VG has a more reasonable heat transfer capacity. Flow characteristics and heat transfer enhancement of concave VGs with 65 different geometric parameters have been analyzed in a rectangular channel under steady flow conditions. It is concluded that the concave VG enhances the heat transfer and reduces the resistance loss. It should be indicated that the highest performance evaluation criteria (PEC) and the increment of PEC are 1.93 and 93%, respectively. Moreover, Nusselt number (Nu) has a strong correlation with volume averaged turbulent dissipation rate and wall shear stress and the correlation coefficient is 0.935.