Effect of Slot Jet on Heat Transfer and Flow Characteristics of Microchannel Heat Sink Partially Filled with Porous Media at High Heat Flow Density and Conjugate Heat Transfer Boundary Conditions

In this paper, a three-dimensional mathematical model of microchannel heat sink slot jet partially filled with porous media coupled heat transfer is constructed with the local thermal non-equilibrium (LTNE) model and the Darcy-Forchheimer model, taking into account the buoyancy effect and the conjugate heat transfer boundary conditions. Copper foam metal is employed as the porous medium substrate and SIMPLE algorithm is used to solve the mathematical model. The coupled effects of porosity (ε), Reynolds number (Re) and thickness of the porous region (h) on the flow and temperature fields are comprehensively evaluated. The numerical results show that for all the cases, the temperature distribution of the fluid and porous medium is not consistent, and the temperature of porous medium is lower in the region perpendicular to the jet inlet due to the stagnation point effect. As the porosity increases from 0.35 to 0.50, the total average Nusselt number on the upper surface decreases from 46.85 to 13.12, while the total average Nusselt number at the interface increases from 2.13 to 2.98. High speed fluids are more prone to deflection after impacting porous media, and the faster the flow velocity inside the square cavity, the easier it is to form a high-speed channel in the middle. The formation of high-speed channel to drive the lower part of the square cavity flow rate, the vortex becomes more flatter and longer, convection heat transfer effect is enhanced. Meanwhile, as the thickness of the porous layer increases, the heat of the porous medium can be easily transferred to the fluid, resulting in an increase in the overall temperature of the square cavity and a larger temperature gradient on the upper surface. The results may provide design ideas for microchannel heat sinks for electronic components.