Forced convection of CuO/water nanofluid in Horizontal Annuluses with rotating inner cylinder

The specifications of forced convective heat transfer of CuO/water nanofluid on the conditions of turbulent flow in concentric annuluses with the rotating inner cylinder were simulated. The comparison between predicted and experimental data of average Nusselt numbers was found to be in good agreement. The CFX solver is used to solve the governing equations numerically. The uniform wall temperatures are considered as thermal boundary conditions. Solutions for the same axial and rotating velocity and the Nusselt number are obtained for different values of the nanoparticle volume fraction and the Reynolds number. In addition, the effects of change of the outer cylinder diameter on heat transfer are also investigated. Simulations show that the increases of the inlet/rotating velocity will enhance the heat transfer. When the inlet velocity increases it increases the axial velocity near the walls and reduces rotating velocity at the mid-gap to achieve the conservation of mass due to the entity of secondary flow in the annulus. On the other hand, the increase of the rotating velocity imposes the larger temperature gradients and a higher heat transfer rate. Moreover, the increasing rate of Nusselt number is substantially lesser than the corresponding increase in high aspect ratio.

کلیدواژه ها:

Nanofluids ، Forced convection ، Annuli ، Rotating velocity ، Turbulence