Enhancement of Heat Transfer and Fluid Flow Characteristics in an Elliptical Tube with a Twisted Tube Section and Twisted Tape Inserts: A Numerical Investigation

This computational study explores the thermal and hydrodynamic behavior of a novel heat exchanger tube design combining a twisted elliptical tube section with twisted tape inserts placed before a regular flat elliptical tube section. The geometric model is analyzed using ANSYS FLUENT software, which applies a finite volume approach and a k-omega omega SST turbulence model. The results indicate that including a twisted section and vortex-induced inserts improves heat transfer efficiency compared to a standard elliptical tube that does not have these features. Notably, the Nusselt number is augmented by 26.36% for the elliptical plain tube with twisted tube section coupled with twisted tape inserts at pitch=0.05 m , and 10.9% for the elliptical plain tube with twisted tube section at pitch=0.05 m, relative to the elliptical plain tube configuration. The smaller twist pitch of 0.025 m is found to yield the highest Nusselt number and performance evaluation criterion (PEC). The configuration with the tightest pitch of 0.025 m shows a higher heat transfer performance, resulting in the highest Nusselt number and PEC. Specifically, this design achieves a significant 67.3% increase in Nusselt number compared to the standard channel, along with a peak PEC value of 1.128. But, this significant thermal improvement comes at the cost of increased flow resistance. The friction factor increases by 46.56% with both the twisted section and vortex generators, and by 14.62% with the twisted section only, compared to the basic smooth channel design.