Numerical Investigation of Flow and Heat Transfer in a Serpentine-Oval-Cell Composite Heat Transfer Tube

This study tackles the issue of low heat transfer efficiency in conventional heat exchange tubes through a biomimetic design approach. Inspired by the surface-guiding characteristics of snake skin and the fluid-directing features of oval cells, a novel composite heat exchange tube integrating a snake-like wavy inner rib and an elliptical T-cell structure was developed. Numerical simulations were conducted to investigate the effects of different rib arrangements, rib numbers, and spacings on the heat transfer characteristics of the tube over a Reynolds number range of 8,000–18,000. The results indicate that variations in rib configuration, number, and spacing have a significant impact on heat transfer performance. Under the condition of Re = 8,000, the optimal configuration achieved a maximum overall heat transfer performance (PEC) of 1.21, with the average Nusselt number (Nu) enhanced by 89% compared to a smooth tube. Moreover, at the same Reynolds number, the wavy inner rib T-cell tube exhibited lower pressure loss than other types of composite heat exchange tubes while maintaining comparable PEC, and demonstrated better flow resistance characteristics than both single rib and T-cell tubes. These findings confirm that the proposed structure effectively reduces energy loss while sustaining efficient heat transfer. Finally, field synergy analysis revealed the intrinsic mechanism by which the composite structure enhances heat transfer through improved coordination between the velocity and temperature fields. This study provides a theoretical foundation for the design and optimization of advanced composite internally ribbed heat exchanger structures.