Thermal Performance of Elliptical Fin-and-Tube Heat Exchangers with Vortex Generator under Various Inclination Angles

Elliptical fin-and-tube heat exchangers are commonly used in air conditioning, heating, refrigeration industries, and ventilation. This study numerically investigates the effect of vortex generators on the performance of elliptical fin-and-tube heat exchanger under different inclination angles. In this study, air flow that is in the transitional regime is selected as the working fluid. Reynolds numbers at the inlet are varied in a range of 1300 to 2100, and the shear stress transport k - ω turbulence model is selected to solve the non-closure of basic turbulence equations. The ellipticity ratios of the tubes which are used for the analysis are between 0.6 and 1.0, and the inclination angles are varied from 15° to 75°. The effects of different inclination angles of vortex generators on the Colburn factor j , friction factor f , and efficiency index j / f are analyzed. The friction and Colburn factors are observed to increase with increasing vortex generator inclination angles. It is found that the efficiency factors for a 15° vortex generator inclination angle at 0.6, 0.7, 0.8, and 0.9 ellipticity ratios improve compared to the corresponding cases with no vortex generator. However, the vortex generator cannot improve the efficiency factor of the circular tube heat exchanger. The 3D CFD method employed by this study has great potential for use in optimally designing the arrangement of the vortex generators to enhance the performance of heat exchangers.