Abstract
This article demonstrates the feasibility of porous separation on the performance of displacement ventilation in a rectangular enclosure. A jet of fresh air enters the cavity through an opening at the bottom of the left wall and exits through an opening at the top of the right wall. The porous separation is placed in the center of the cavity and its height varies between 0.2 and 0.8 with three values of thickness, 0.1, 0.2, and 0.3. The heat transfer rate was calculated for different intervals of Darcy (10−6 ≤ Da ≤ 10), Rayleigh (10 ≤ Ra ≤ 106), and Reynolds (50 ≤ Re ≤ 500) numbers. The momentum and the energy equations were solved by the lattice Boltzmann method with multiple relaxation times (LB-MRT). Schemes D2Q9 and D2Q5 were chosen for the velocity and temperature fields, respectively. For porous separation, the generalized Darcy–Brinkman–Forchheimer model was adopted. It is represented by a term added in the standard LB equations. For the dynamic domain, numerical simulations revealed complex flow structures depending on all control parameters. The results showed that the thermal field, mainly in the second compartment, is very dependent on the size and permeability of the porous separation. However, they have no influence on the transfer rate.
Highlights
Heat transfer in enclosures has been of great interest to researchers due to the many applications arising from such geometries
Due to the multiple parameters controlling the flow pattern, temperature field, and heat transfer, all calculations were performed by setting a constant Prandtl number (Pr = 0.71; the air) and a finite aspect ratio A = 2
Note that the negative values of the stream functions are shown as dotted lines and that the porous medium thickness is taken to be constant at Ep = 0.2
Summary
Heat transfer in enclosures has been of great interest to researchers due to the many applications arising from such geometries. A few years later, Moraga et al [11] used the finite volume method (MVF) to study mixed convection in a ventilated rectangular cavity, vertically divided into two different porous media; they studied the effect of several control parameters such as the Darcy number, Reynolds number, Richardson number, aspect ratio, and flow direction. They found that the friction coefficient of the walls is larger when Re = 500 and Ri = 10 in both flow directions. It presents an interesting solution for enhancing air quality, energy saving, and thermal comfort in buildings
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