Numerical Investigation of Nanofluids Mixed Convection in a Lid-Driven Cavity with Two Heat Sources

Abstract

Heat transfer enhancement through using nanofluids improves energy efficiency and enables energy savings. In this paper, a nanofluids flow and heat transfer are numerically investigated in a cavity. Four nanoparticle types (CuO, Al2O3, ZnO and SiO2) dispersed in the base liquid (water) are considered. The cavity is partially heated by two identical sources placed on the vertical walls. Partial differential equations (PDEs) are solved using (ANSYS R2 (2020) software). The Maxwell physical model and the Brownian motion effect are used to calculate the thermal conductivity and dynamic viscosity considering the diameter of the nanoparticles. Numerical simulations are performed for various parameters including nanoparticle type, nanoparticle volume fraction (0 ≤ Φ ≤ 0.06), nanoparticle diameter (29 nm, 49 nm and 69 nm) and Richardson number (0.1 ≤ Ri ≤ 10). The streamlines, isotherms, and average Nusselt number are analyzed. The results of this study showed that the average Nusselt number increases with increasing the volume fraction of nanoparticles, and decreases with incrementing the nanoparticle diameter. The heat transfer increases as the Richardson number increases. The nanofluid SiO2-water is suggested as it showed the highest heat transfer rate among the investigated nanofluids. Using Φ = 6% nanoparticles with a diameter of 29 nm improves the average Nusselt number by 6.81%, 2.43% and 0.96% for SiO2, Al2O3, ZnO, respectively, when compared to CuO, for the right-wall (Nuaverage(1)), and 6.70%, 2.40% and 0.84% for the left wall (Nuaverage(2)).