Numerical study on application of orthogonal elliptic tube in torsional flow heat exchanger

•A new structure of the torsional flow heat exchanger was presented.•Periodic model was used in both the tube and shell side.•Local heat transfer and flow resistance analysis at key positions was performed.•The principle of enhanced heat transfer was analyzed according to the field synergy.•The model reliability was verified experimentally. Orthogonal elliptical tube are highly applied in torsional flow heat exchanger to optimize the heat transfer performance and reduce the flow resistance. A full-section periodic model of the torsional flow heat exchanger with orthogonal elliptical tube with four axial ratios is established. The heat and flow transfer on the tube and shell sides are numerically simulated with the computational fluid dynamics(CFD) method. Besides, the transfer performance on the shell side is evaluated based on the field synergy principle. The results show that compared with the round tube, for the tube side, the convective heat transfer coefficient of the orthogonal elliptical tube is increased by 26.7–73.2 %, and the comprehensive performance is increased by 6.4–25.6 %.On the shell side, the heat transfer coefficient of the torsional flow heat exchanger with orthogonal elliptical tube is increased by 4.5–16.8 %, the pressure drop is reduced by 17.1–21.3 %, and the comprehensive performance is improved by 14.8–34.7 %. The comprehensive performance of the orthogonal elliptical tube with an axial ratio of 1.7 on the shell side is the best. This research provides ideas and theoretical references for the development of special-shaped tube torsional flow heat exchanger.