MHD enhanced nanofluid mediated heat transfer in porous metal for CPU cooling

Abstract

In this study, impingement cooling of a porous metal CPU cooler saturated with nanofluid under the effects of magnetic field was modeled analytically. Darcy-Brinkman-Forchheimer model and viscous dissipation effect were considered to simulate fluid flow of nanofluid through the porous media under magnetic field. Proper similarity variables were proposed and the original partial differential governing equations were converted to nonlinear ordinary differential equations (ODEs), and the resulted ODEs were solved numerically. A system of water-alumina nanofluid flowing through a rectangular porous metal foam with top impinging jet (fan) and hot bottom wall (CPU surface) was modeled. The analytical solver was first validated against CFD and experimental data. Next, effects of different critical parameters including Darcy number (5×10-4≤DaL≤5×10-2), Reynolds number (50≤ReL≤500), aspect ratio (0.25≤H/L≤1.0), Eckert number (0≤EcL≤5×10-2), Hartmann number (0≤HaL≤200), porosity (0.85≤ε≤0.95), and dimensionless distance from the axis of symmetry plane (0≤XL≤1.0), on fluid flow and heat transfer behaviors were investigated. Results indicate that the increase of DaL can enhance heat transfer performance, while opposite trends are found for aspect ratio and Eckert number. However, the behavior of HaL is more complex. At a low porosity, Nusselt number slightly decreases as HaL increases, while an opposite behavior is observed at a high porosity. Overall, the use of a stronger magnetic field is beneficial to enhance the impingement cooling heat transfer with highly porous metal foam.