Numerical investigation and optimization of shell-and-tube heat exchangers with inclined folded helical baffles

In the field of industrial waste heat recovery, helical baffle shell-and-tube heat exchangers are widely used due to their compact configuration and superior thermal performance. However, conventional quadrant helical baffle designs often create triangular leakage zones, resulting in non-uniform flow on the shell side and reduced heat transfer efficiency. To address this limitation, a novel inclined folded helical baffle design is proposed. Numerical simulations were conducted to compare the flow and thermal performance of the inclined folded and quadrant helical baffle designs under identical operating conditions, and a response surface methodology was applied to optimize key structural parameters. A quantitative method was developed to evaluate the helical flow tendency and leakage intensity, providing a clear assessment of the shell-side flow behavior. The results demonstrate that the inclined folded helical baffle effectively suppresses leakage, enhances cross-flow sweeping, and improves the synergy between velocity and temperature fields. Within a Reynolds number range of 5000–10000, the inclined folded design outperforms the quadrant configuration by 10.24 %–12.46 % in the performance evaluation criterion. Sensitivity analysis identifies baffle spacing as the most influential parameter, with a strong interaction effect with the Y-axis steering angle. Further optimization increases the performance evaluation criterion by an additional 5.02 %, with the optimal parameters determined as a 34.73° Y-axis steering angle, a 35.28 mm longitudinal turning length, and −0.5 mm baffle spacing. This study provides practical guidance for shell-side structural optimization and offers engineering insights for enhancing energy efficiency in industrial heat recovery systems. • A novel inclined helical baffle is introduced to address triangular leakage zones. • Field synergy analysis reveals lower deviation angles and enhanced thermal alignment. • A method is developed to quantify helical flow tendency and leakage intensity. • RSM is employed to assess interaction effects and optimize structural design.