Thermo-Hydraulic Performance and Entropy Generation Analysis of Serpentine and Straight Tubes with Twisted Tape Inserts Using SST k-ω Turbulence Modeling
Conghai Chen1, Dingran Sun2, Yikai Chen2, Jianxin Xu2,*, Hua Wang2
1 State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, School of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, China
2 Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, China
* Corresponding Author: Jianxin Xu. Email: 
Fluid Dynamics & Materials Processing https://doi.org/10.32604/fdmp.2026.082984
Received 26 March 2026; Accepted 12 May 2026; Published online 01 June 2026
Abstract
Serpentine heat exchangers are extensively used in energy and chemical engineering owing to their compact geometry and high thermal performance. To improve their efficiency, three-dimensional numerical simulations are conducted using the SST
k-
ω turbulence model for both serpentine and straight tubes fitted with twisted tape inserts. Three twist ratios (
y = 5.77, 8.57, 12.48) are examined across a Reynolds number range of 10,000 to 22,000. Results show that the average Nusselt number increases with Reynolds number, while the friction factor decreases. In particular, due to curvature-driven secondary motions, serpentine configurations consistently outperform straight tubes in thermal performance. The addition of twisted tapes intensifies fluid mixing through strong swirl generation, disrupting the thermal boundary layer and significantly enhancing heat transfer, albeit with increased flow resistance. Among all cases, the lowest twist ratio (
y = 5.77) generates the strongest swirl intensity and highest turbulent kinetic energy, yielding maximum thermal augmentation but also the greatest pressure drop. Performance Evaluation Criterion analysis indicates
PEC > 1 for all twisted tape configurations under equal pumping power, confirming an overall beneficial trade-off between enhancement and hydraulic penalty. Entropy generation results further demonstrate that improved thermal performance is accompanied by higher irreversibility. Overall, the combination of serpentine geometry with low to moderate twist ratios offers the most favorable thermo-hydraulic balance for compact heat exchanger optimization.
Keywords
Serpentine tube; twisted tape inserts; turbulent heat transfer enhancement; entropy generation analysis; thermo-hydraulic performance
Open Access
Login
Register
Submit a Paper
Propose a Special lssue
Download PDF
Downloads
Citation Tools
