Thermal Performance of Elliptical Fin-and-Tube Heat Exchangers with Vortex Generator under Various Inclination Angles
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https://doi.org/10.1007/s11630-020-1305-3
Article ID: 1003-2169(2020)00-0000-00
Thermal Performance of Elliptical Fin-and-Tube Heat Exchangers with Vortex Generator under Various Inclination Angles WANG Yucheng1,2, ZHAO Wensheng1,2*, WANG Pengfei1,2, JIANG Jin1,2, LUO Xiangyu2 1. Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan University, Wuhan 430072, China 2. School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China © Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract: 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.
Keywords: heat exchanger, vortex generator, Colburn factor, friction factor, heat exchanger efficiency
1. Introduction Elliptical fin-and-tube heat exchangers are commonly used in air conditioning, heating, refrigeration industries, and ventilation. Compared with the traditional shell-and-tube heat exchanger, the fin-and-tube heat exchanger has the advantages of higher heat transfer coefficient, compact structure, pure countercurrent, and lower final temperature difference. There are typically several methods to study the enhancement of heat exchange performance of the fin-and-tube heat exchanger.
Received: May 13, 2019
AE: LI Hongqiang
First, the diameter of the heat exchanger tubes can be reduced while reducing the transverse and longitudinal spacing of tube rows. Second, an elliptical fin-and-tube can be used and placed at a certain inclination angle. Third, the degree of disturbance of the air side can also be increased, where the common method is to use corrugated
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