Configuration optimization of regularly spaced short-length twisted tape in a circular tube to enhance turbulent heat transfer using CFD modeling

Abstract

Abstract This work presents the configuration optimization of regularly spaced short-length twisted tape in a circular tube for turbulent heat transfer in air using computational fluid dynamics (CFD) modeling. The configuration parameters include the free space ratio ( s ), twist ratio ( y ) and rotated angle ( α ). The computational results are in good agreement with experimental data. The results indicate that the larger rotated angle yields a higher heat transfer value and a greater flow resistance, whereas the smaller twist ratio results in better heat transfer performance using a twist ratio ranging from 2.5 to 8.0 except for a large rotated angle and a high Reynolds number (e.g., α = 360 ° and Re = 20,200). However, the minimum resistance factor occurs if the twist ratio is in the range of 4.75–5.75. The optimal design of regularly spaced short-length twisted tape in a circular tube for turbulent air flow is y = 4.25–4.75, α = 180° and s = 28–33 with a Reynolds number that varies from 10,000 to 20,200. If the heat transfer rate is more important, the second design of y = 4.25–4.75, α = 270° and s = 28–33 in the range of Reynolds numbers from 10,000 to 20,200 can be used as a reference for industrial application.