A Computational Study for Evaluating the Performance of Twisted Double Tube Heat Exchangers Fitted with Twisted Tape

Twisted double-tube heat exchangers are promising in improving the heat transfer efficiency on the tube side, decreasing the pressure drop on the shell side, and reducing the size of the equipment. Although offering immense potential, examining heat transfer enhancement techniques inside a heat exchanger. In this study, The thermal-hydraulic characteristics of twisted double-tube heat exchangers fitted with twisted tape inserted have been numerically studied. The Naiver-stokes, energy, and turbulence equations were used to model the fluid flow and heat transfer while the turbulence was with a k- ε model. ANSYS Fluent 23.1 was used to solve the governing equations. The effect of major design elements such as mass flow rate, varied pitches of twisted double tubes and twisted tape inserts was investigated. The hot water was used in the inner tube and the cold water in the outer tube to create a counter-flow apparatus. The Length of the heat exchanger was 1 meter, and the outer and inner diameter was 0.054 and 0.018 m respectively. The thickness of the two tubes was 0.004 m. The twisted ratio of the tubes was tested for =5, 10, and 15 while the twist ratio of the tape was 4, 6, and 8. The findings demonstrated that the utilization of a double twisted tube heat exchanger with a twisted tape insert resulted in enhanced heat transfer in comparison to a plain tube heat exchanger. The numerical analysis revealed that as the twisting ratio drops, the Nusselt number, pressure drop, and overall heat transfer coefficient increase.