CFD study of heat transfer enhancement and fluid flow characteristics of turbulent flow through tube with twisted tape inserts

A three-dimensional computational conjugate heat and mass transfer study has been carried out using computational fluid dynamics (CFD) software package ANSYS FLUENT to investigate the effect of insert's twist ratio on the heat transfer and fluid flow performance. Investigation was carried out for air flow at 300 Kelvin and Reynolds number ranging from 3642 to 21857 through a tube with constant wall heat flux of 8000 W/m2. Validating against Gneilski and Petukhob models, the current model has been used to investigate the effect of insert with twist ratio 3.46 and 7.6 on Nusselt number, friction factor and thermal performance factor of the tube. Results show that for twist ratio of 3.46, Nusselt numbers and friction factors are increased by 20% to 62% and 185% to 245% respectively, and thermal performance factor ranged between 0.9 and 1.2. Those were observed to be increased by 10% to 30%, 128% to 183% and ranged between 0.95 to 1.05 respectively for twist ratio of 7.6. It is concluded that twisted tapes provide better heat transfer enhancement at relatively lower Reynolds number and twist ratio.