Thermo-hydraulic performance analysis of converging-diverging heat exchanger with inclined fins using computational fluid dynamics

Abstract

The combination of geometric parameters for improving the overall performance of heat exchangers is a promising approach that has been widely investigated to date. The thermo-hydraulic performance of a converging-diverging shell and tube heat exchanger using hybrid geometrical parameters is numerically evaluated in this study. Although the noticeable impacts of converging-diverging channels in heat transfer improvement have been confirmed in the literature, the converging-diverging shell and tube heat exchanger with inclined fins is a topic that researchers have not looked at before. The turbulent RNG k-ε model is considered for the counter-current flow in the shell and tube sections using computational fluid dynamics. Different geometries, including four, seven, and ten convergences along the shell, number of the fins (n = 0, 2, 4, 8), and the fins inclination angles (a = 45o, 90o) are analyzed comprehensively in twenty-eight cases. The streamlines demonstrate a zigzag flow pattern in the converging-diverging shell which provides better mixing. The results based on the Colburn factor and friction factor indicate that the converging-diverging geometries present a higher heat transfer rate between 50.67%-60.86% with a 73.45%- 86.90% pressure drop penalty compared to the cylindrical heat exchangers. Also, the inclined fins enhance the heat transfer up to 21.65% compared to the vertical fins. Finally, the optimum configuration of the heat exchanger is introduced, considering the area goodness factor.