Heat Transfer Enhancement and Flow Resistance Characteristics in a Tube with Alternating Corrugated-Smooth Segments

To mitigate the inherent high flow resistance of conventional corrugated tubes, a novel design with alternating clockwise/counterclockwise corrugated segments separated by smooth sections is proposed. A 3D numerical model was developed to systematically evaluate the thermal-hydraulic performance of the novel tube against smooth and conventional corrugated tubes, with simulations conducted at Reynolds number (<i>Re</i>) = 9952–35,827. Results show both corrugated configurations enhanced heat transfer significantly relative to the smooth tube: the conventional tube had the highest Nusselt number (<i>Nu</i>) (1.76–1.79 times that of the smooth tube), while the novel tube achieved <i>Nu</i> = 1.61–1.65 times that of the smooth tube. Notably, the novel tube reduced flow resistance substantially—at <i>Re</i> = 35,827, its friction factor (<i>f</i>) was only 65.2% of the conventional tube’s. Parametric studies revealed that more corrugated segments improved heat transfer but increased pressure drop: the 72-12 configuration exhibited the best heat transfer, while the 72-2 configuration reduced <i>f</i> by 40.7%. The novel tube showed superior overall performance (Performance Evaluation Criterion (<i>PEC)</i> > 1.24 for all <i>Re</i>), as corrugated segments generated periodic vortices to disrupt the thermal boundary layer, while smooth segments enabled flow redevelopment and pressure recovery. This study provides valuable guidance for designing high-efficiency, low-resistance heat exchange elements.