Numerical study of heat transfer augmentation in an axially rotating pipe equipped with Kenics mixer

Abstract

This paper reports fluid flow and heat transfer in an axially rotating pipe equipped with Kenics mixer under constant wall heat flux condition. Numerical simulations were processed with the commercial finite volume CFD code, ANSYS Fluent 19.2. The realizable k-ε turbulent model was used to close the Reynolds Average Navier-Stokes (RANS) equations. Buoyancy effects (βΔT) and gravity (g = 9.81 m/s2) were considered in the simulations. In the range of axial Reynolds numbers between 10,000 and 30,000 (10,000 ≤ Rea ≤ 30,000), the Kenics mixer enhanced the Nusselt number of the rotating pipe by 41–50%, 38–47% and 33–42% at rotation rates of 1, 2 and 3 respectively. Enhancement in Nusselt number was linked to additional swirl created by the Kenics mixer insert which improved fluid mixing and boundary layer disturbance. CFD results also showed that increasing the axial Reynold number augmented the Nusselt number but decreased the friction factor.

Keywords

• Nusselt number
• Swirl
• Rotation rate
• Kenics mixer
• CFD