Heat transfer enhancement of laminar impinging slot jets by nanofluids and metal foams

A study on impinging slot jets in a confined channel filled with metal foam, saturated with nanofluids, and lower wall partially heated is numerically accomplished. The partially heated wall is at an assigned temperature and buoyancy effects are taken into consideration. A two-dimensional domain is analyzed considering the local thermal non-equilibrium for the metal foam and the single-phase model is assumed to simulate the nanofluids at assigned Rayleigh number for several Peclet numbers. The governing equation solutions are accomplished using the Ansys-Fluent code and simulations are carried out for aluminum foams with nanofluids, Al2O3/water based, as working fluids. Several porosity values, from 0.90 to about 0.97, for different pore density, pore per inches (PPI), from 5, to 40 PPI, are used. The volumetric concentrations change from 0% to 5% with a particle diameter of 30 nm. The distance between the slot jet outlet section and the lower heated surface is five times the slot jet width. The presented results point out that the dimensionless convective heat transfer coefficients increase with increase in values of Peclet number, and decrease with the volumetric concentration. It is noted that the surface heat transfer coefficient shows different behavior varying porosity for assigned Peclet and Rayleigh numbers. Some correlations for the average total Nusselt number in terms of porosity and volumetric concentration are proposed in quadratic forms for assigned pore density and Peclet number.