Numerical analysis of nano-fluid flow and heat transfer in ducts

In this study, turbulent nanofluid flow and heat transfer in a square duct with constant heat flux at the top and bottom surfaces and insulated front a back faces were investigated numerically. Fluent was used for the numerical solution of the governing equations of the problem. To model the turbulence, realizable k-model is used. The finite volume method (FVM) was used to discretize the continuity, momentum and energy equations. Three different types of nanoparticles Al2O3, ZnO, and CuO with different diameters (30, 29, 29 nm) at different volume fractions (in the range of 1% to 4%) were considered. Effects of these parameters on heat transfer rate and flow characteristics in the Reynolds numbers range of 10000 to 35000 were studied. The results of the simulations show a good agreement with the existing experimental correlations. The numerical results show that Al2O3-water has the highest Nusselt number compared to other nanofluids considered while it has the lowest heat transfer coefficient due to low thermal conductivity. It was observed that the Nusselt number increases with the increase in the Reynolds number and the volume fraction of nanoparticles.