Performance and structure optimization of torsional flow heat exchanger with orthogonal drop-shaped tube

As a novel variation of shell-and-tube heat exchanger, torsional flow heat exchanger has a promising application prospect, while drop-shaped tube can enhance fluid flow velocity, distribution, and overall heat transfer performance. A torsional flow heat exchanger with orthogonal drop-shaped tubes in the shell side is presented to obtain the benefits of both designs. Three numerical models about torsional flow heat exchangers are established, having the same structure but different in the axial ratio of the heat transfer tubes. The characteristics of fluid flow and heat transfer in the shell side of heat exchangers are analyzed numerically. Response surface method is utilized to optimize the shell-side structure. The results show that compared with the torsional flow heat exchanger with common round tubes, torsional flow heat exchangers with orthogonal drop-shaped tubes of three axial ratios at the Reynolds number range from 5000 to 13000, pressure drop reduces by 9.26%-14.49%, heat transfer coefficient increases by 0.65%-11.57%, and comprehensive performance improves by 14.18%-27.23%. The optimum structure of the torsional flow heat exchanger with orthogonal drop-shaped tubes is predicted by using Minitab and compared to the initial structure, resulting in 17.19% improvement in heat transfer coefficient and 18.63% improvement in comprehensive performance. The study provides a reference for the structural exploration and improvement of torsional flow heat exchangers with enhanced tubes.