Effect of Twisted Tapes Insert on Heat Transfer and Pressure Drop Augmentation for High Viscous Fluids inside Rotating Tubes

Abstract

The present work shows the results obtained from the numerical simulation of the heat transfer enhancement for the high viscous flow inside horizontal axially rotating tubes, using twisted tapes with the different twist and width ratios. The simulation is performed with the twisted tapes of three twist ratios (TR = 5, 7.5 and 10) and four width ratios (WR = 0.9, 0.7, 0.5 and 0.3). Rotation Reynolds number and Reynolds number are ranged from 0.9 to 5927 and 5 to 849, respectively. A computational fluid dynamics (CFD) methodology using ANSYS FLUENT 14.0 is used to perform the numerical analysis by solving the Navier-Stokes and energy equations through the viscous model at all cases of rotation Reynolds numbers and Reynolds numbers. The results revealed that, thermal performance factor due to the insertion of the twisted tapes in rotating tubes is strongly depended on the rotation speed. The increase in rotation speed decreases the thermal performance factor for tubes with Engine oil and Oil (SN-500). Whereas, in the tubes with Ethylene glycol, the thermal performance factor increases as the rotation speed increases. The influence of the twist ratio variation on the friction factor and heat transfer is small, as compared with the tape width ratio. The best twisted tape geometry, to achieve best thermal performance is found at WR of 0.9 for tubes with Engine oil and Oil (SN-500), and 0.5 for tubes with Ethylene glycol.