Numerical study of mixed convection on jet impingement cooling in a horizontal porous layer under local thermal non-equilibrium conditions

The present study numerically investigates the mixed convection arises from jet impingement cooling of an isothermal heated surface immersed in a confined porous channel under local thermal non-equilibrium conditions. The heat transfer characteristics are investigated with a parametric study over wide ranges of governing parameters: the Rayleigh number (10⩽Ra⩽200), Péclet number (1⩽Pe⩽104), Darcy number (10−6⩽Da⩽10−3), porosity (0.75⩽φ⩽0.99), heat transfer coefficient between solid and fluid (1⩽H⩽103), and porosity scaled thermal conductivity ratio (0.001⩽Kr⩽5). The results are presented as average Nusselt numbers against Péclet number. Minimum Nusselt numbers are found at some values of Péclet number in the mixed convection regime. The results show that, increasing H or/and Kr lead to increase of total average Nusselt number and render the solid and fluid towards thermal equilibrium conditions. The effects of Darcy number, Rayleigh number and porosity on average Nusselt numbers has been evaluated for different value of H and Kr or thermal conductivity ratio between solid and fluid (kf/ks). The results show that, the deterioration of heat transfer rate is more significant at higher values of Rayleigh number. The total average Nusselt number could be enhanced by increasing the value of porosity.