Thermo-hydraulic performance evaluation of turbulent flow and heat transfer in a twisted flat tube: A CFD approach

Abstract

The numerical procedure for turbulence fluid flow and heat transfer in a twisted flat tube is presented in this work. For the cross-section of the flat tube, three different geometries are investigated. Water is a working fluid with constant thermophysical properties. The Reynolds number ranges from 5000 to 20000. Results show that by using twisted flat tubes, the efficiency has increased nearly 70% compared to the smooth tubes with the same surface area and hydraulic diameter. Also, the alternating helical direction has caused almost 60%, which seems to be a good choice. Due to the effect of helical pitch that affects the flow path, the alternating geometry was better in some Reynolds and not others. The results are explained using flow characteristics contours such as turbulent kinetic energy, tangential velocity, and temperature. Moreover, the results are presented in numbers and plots for a more accurate comparison.

Keywords

• Heat transfer enhancement
• Twisted flat tube
• Swirling flow
• Turbulence flow
• Numerical method