Enhancing Thermal Performance in Double Pipe Heat Exchangers Using Combined Twisted Tape and Helical Tape Inserts: A Comprehensive Review and Research Framework

This research explores the potential of systematic review and research framework to improve how efficiently heat is transferred in double pipe heat exchangers (DPHEs) using combined passive techniques—internal twisted tape inserts placed inside the pipe and helical tapes wrapped around the outside. Despite extensive studies on individual enhancement methods, a significant research gap exists in understanding their synergistic effects. This review synthesizes key findings from numerical and experimental studies on twisted tape geometries, thermal performance factors (TPF), and entropy generation. It identifies critical gaps, including the lack of empirical correlations for combined inserts and insufficient analysis of thermodynamic efficiency. The proposed research aims to evaluate how the Nusselt number and friction factor change with different Reynolds numbers develop empirical correlations for design optimization, and conduct entropy generation analysis to minimize irreversibility. The findings will contribute to the design of energy-efficient DPHEs for real-world industrial uses.