Numerical study of the intensity correlation between secondary flow and heat transfer of circle tube-finned heat exchanger with vortex generators

Abstract

The application of vortex generators in tube-finned heat exchangers is very universal. The vortex generators can generate secondary flow, and as we all know secondary flow can obviously strengthen heat transfer. To use vortex generators much more efficiently in the circle tube-finned heat exchangers, the intensity correlation study between secondary flow and heat transfer is needed. 22 different structures of circle tube-finned heat exchangers were numerically studied, including the plain fin cases and the cases with vortex generators. In addition, the influence of fin spacing, transverse and longitudinal tube pitch, heights and attack angle of vortex generators, positions of vortex generators and shape of vortex generators on heat transfer and fluid flow are studied, too. The non-dimensional parameter Se is applied to quantify the secondary flow intensity. The results show that Se can describe the secondary flow intensity very well. There is very close corresponding relationship between overall averaged Nu and volumetrically averaged Se for all the researched cases and the relational expression is obtained. However, there is no one-to-one correlation not only between Re and f but also between volumetrically averaged Se and f for all the studied cases.