Correlations on heat-transfer rate and friction factor using radial and axial v-cut geometry on a twisted tape in a double-pipe heat exchanger

Abstract

This study explores the transformative potential of varying radial and axial v-cut angles within twisted tape inserts in the context of heat transfer enhancement within a double-pipe heat exchanger. The research is driven by the need to enhance energy efficiency in heat exchange systems, with a focus on understanding how v-cut angles influence heat-transfer rates, friction factors, and overall performance. Using water as the working medium, a comprehensive experimental investigation is conducted across a Reynolds number range of 5500–10,000. The findings reveal compelling correlations between the Nusselt number (Nu), friction factor ( f), and performance evaluation criteria concerning different v-cut angles within the twisted tape inserts. Remarkably, the study underscores the pivotal role of radial v-cut twisted tapes in elevating heat exchanger performance, surpassing even axial v-cut configurations. The Nusselt number achieves its pinnacle (96.51) at a Reynolds number of 10,000, whereas the highest friction factor (0.0582) and performance evaluation criteria (1.65) emerge at a Reynolds number of 5500, specifically with a 45-degree radial v-cut angle. This configuration showcases remarkable enhancements in the Nusselt number (98.68%), friction factor (38.87%), and performance evaluation criterion (39.36%) compared to a plain tube, underlining the transformative potential of optimized twisted tape inserts. The presented study offers more than theoretical insights; it provides practical guidelines for designing heat exchangers with superior performance. Derived correlations for the Nusselt number and friction factor, established through regression analysis involving key parameters such as Reynolds number (Re), Prandtl number (Pr), radial v-cut angle ( ϕ), and axial v-cut angle ( θ), demonstrate robust results within a narrow range of ± 5% for the Nusselt number and ±7% for the friction factor. In summary, this investigation not only advances our understanding of heat transfer enhancement but also presents tangible pathways for implementing enhanced heat exchanger designs, contributing significantly to energy-efficient thermal systems.