Numerical Investigation on Heat Transfer in Confined Impinging Slot Jets with Nanofluids in Partially Filled Configuration of Metal Foam

In this paper a numerical investigation on mixed convection in confined slot jets impinging on a partially filled configuration of porous medium by considering pure water or Al2O3/water based nanofluids is described. A two-dimensional model is developed and different Peclet numbers are considered. Rayleigh numbers is imposed equal to 30000. The particle volume concentration ranges from 0% to 4% and the particle diameter is assumed equal to 20, 30 and 80 nm. The target surface is heated at constant temperature value, calculated according to the value of Rayleigh number. The distance of the target surface is five times greater than the slot jet width. Three different values of the ratio between the total system length and metal foam length are considered. A single-phase model approach is employed in order to describe the nanofluid behaviour while the hypothesis of non-local thermal equilibrium is assumed to simulate the thermal behaviour in the metal foam. The foam is characterized by a number of pores per inch equal to 5, 10, 20 and 40 and a porosity around 0.90. The aim of the paper consists to study the thermal and fluid-dynamic behaviour of the impinging jet system with nanofluids. Results show increasing values of the Nusselt number for increasing values of Peclet number and nanoparticle concentration. In addition, the ratio between the thermal and pumping power is evaluated to find a trade-off between the increase of heat transfer and pressure drop.