Mixed-convection flow of Al_2O_3-H_2O nanofluid in a channel partially filled with porous metal foam: Experimental and numerical study

摘要

Mixed-convection flow of nanofluids inside a vertical rectangular channel partially filled with open-cell metal foam and subject to a constant wall-heat flux was investigated experimentally and numerically. Al_2O_3-water nanofluids with different concentrations were prepared and their stability was examined using UV-Vis spectroscopy. Dynamic light scattering method was used to determine particle size distribution of the nanofluid feedstock. The outlet temperature and pressure drop were measured for different nanofluid flow rates (i.e., Reynolds number values). In the numerical section, a two-dimensional volumeaveraged form of the governing equations was used. The velocity and temperature profiles of nanofluid were obtained using finite difference method. Effects of nanoparticles Brownian and thermophoretic diffusions were taken into account in the governing equations and the local thermal equilibrium assumption was made for the solid and fluid phases. The simulation results were validated against those obtained experimentally and acceptable agreement was found.