Numerical Investigation of Thermohydraulic Performance in Cylindrical Heat Exchangers Featuring Semicircular Twisted‐Tape Inserts

Abstract

Improving the energy efficiency of thermal systems has become increasingly important for the development of compact and high‐performance heat exchangers (HEs). Among various passive enhancement techniques, twisted‐tape inserts have demonstrated significant potential for improving heat transfer without additional energy input. In the present study, a three‐dimensional computational fluid dynamics investigation was carried out to evaluate the thermohydraulic performance of tube‐type HEs equipped with semicircular‐cut twisted‐tape (SCTT) inserts. The effects of semicircular‐cut diameter (5, 8, and 11 mm) and twist ratio (TR) (4.5, 6.0, and 7.5) were systematically analyzed over a Reynolds number range of 4000–16,000. The numerical model was validated against published experimental data and well‐established empirical correlations, with maximum deviations of 6.4% for the Nusselt number and 8.6% for the friction factor. The results indicate that the SCTT inserts significantly enhance convective heat transfer by inducing strong swirl flow, secondary vortices, and improved radial fluid mixing, thereby promoting continuous disruption of the thermal boundary layer. Heat‐transfer performance increased with increasing Reynolds number, decreasing TR, and increasing cut diameter. The highest Nusselt number, 196.38, was achieved with an SCTT insert featuring a TR of 4.5 and a cut diameter of 11 mm. Although the inserts increased the friction factor due to greater flow resistance, the thermal performance factor remained above unity (1.141–1.801) across all configurations, demonstrating that the heat‐transfer enhancement outweighed the associated pressure‐drop penalty. Overall, the optimized SCTT configuration offers a simple, passive, and energy‐efficient solution for enhancing the thermohydraulic performance of tube‐type HEs.