Effect of multi-leg twisted tape inserts on heat transfer and pressure drop characteristics of a laminar pipe flow: A comparative analysis

Improving heat transfer is critical for enhancing energy efficiency in thermal systems, particularly under laminar flow conditions. Traditional twisted tape inserts are effective but often result in an imbalance between heat transfer and pressure drop. This study investigates novel multi-leg twisted tape designs (2-twist, 3-leg, and 4-leg configurations) to optimize thermal performance while managing hydraulic penalties. Using ANSYS Fluent 19.2, CFD simulations were conducted for Reynolds numbers between 800 and 2000 to evaluate heat transfer (Nusselt number), friction factor, and Thermal Performance Factor (TPF). Results validated against experimental data showed that the 2-twist design achieved the best TPF (1.44), followed by the 3-leg (1.40) and 4-leg (1.31). The Nusselt number improvements were 134.16%, 152.19%, and 153.32%, respectively, while friction factor increases were 329.41%, 486.87%, and 630.09%. Although complex designs enhanced heat transfer, they introduced significant hydraulic penalties, with the 2-twist configuration offering the best trade-off. These findings contribute to understanding heat exchanger optimization and highlight opportunities for refining multi-leg twisted tape designs to balance performance and efficiency.