Convegni ATI - Accesso riservato soci CTI

Autore: B. Buonomo, O. Manca, P. Mesolella, S. Nardini

Collana: CA - 66 - Rende 2011

Note:
Steady state mixed convection in air in two parallel plates with porous media is numerically investigated. The parallel plates are partially heated with the two principal flat plates at uniform temperature and adiabatic extensions downstream. The numerical analysis is carried out in two dimensional laminar steady state regime and in local thermal non-equilibrium. The fluid between the two plates is air. The study is carried out employing Brinkman-Forchheimer-extended Darcy model and two energy equations. The physical domain consists of two parallel plates which form a channel and the adiabatic extensions downstream to the heated walls. Both plates are heated at uniform temperature. The flow in the channel is assumed to be two-dimensional, laminar, incompressible. Results in terms of fluid and solid temperatures and velocity profiles along transversal sections at different axial coordinate values, for some Reynolds and Rayleigh numbers and aspect ratios. Average Nusselt numbers are presented for different values of characteristic parameters. Presented results indicate that buoyancy effects are present at the inlet channel for axial coordinate less than 2. For all considered cases fluid dynamic and thermal fields are fully developed at axial coordinate value greater than 2. Solid and fluid temperatures inside the channel are not significantly affect by Reynolds number. Fluid and solid average Nusselt numbers do not depend on Rayleigh number. For all considered geometric ratios, heat transfer in the heated channel is not improved by the adiabatic extension. Whereas for simple heated channel with smaller aspect ratios, an average Nusselt number increase is found for solid and fluid phases. Internal heat transfer in the porous medium is strongly affected by local convective heat transfer coefficient whereas the dependence on solid and fluid conductivity ratios is weak.