Role of porosity and solid-to-fluid thermal conductivity ratio on turbulent combined heat and mass transfer in a porous cavity

In this research, the entropy production of the conjugate heat transfer in a tilted porous cavity in respect to heat source and solid walls locations has been studied numerically. Three different cases of the cavity with finite walls thickness and heat source locations are considered in the present study. For both cases one and two, the cavity considered has a vertical finite walls thickness, while the cavity with the horizontal finite walls thickness is considered for case three. For cases one and two, the left sidewall of the cavity is exposed to heat source, whereas the rest of this wall as well as the right sidewall are adiabatic. The upper and lower cavity walls are adiabatic. For case three, the lower wall is exposed to a localized heat source, while the rest of it is assumed adiabatic. The upper wall is cold, whereas the left and right sidewalls are adiabatic. The flow and thermal fields properties along with the entropy production are computed for the modified Rayleigh number (150 ? Ram ? 1000), thermal conductivity ratio (1 ? Kr ? 10), heat source length (0.2 ? B ? 0.6), aspect ratio (0.5 ? AR ? 2) and walls thickness (0.1 ? D1 ? 0.2 and 0.1 ? D2 ? 0.2) respectively. The results show that, the maximum values of the entropy generated from fluid friction develop close to the cavity wall-fluid interfacial, while the maximum values of the entropy generated from heat transfer develop nearby the heat source region. The average Bejan number (Beav) is higher than (0.5) for cases one and two. While for case three, it was found to be less than (0.5). Also, the results show that as the modified Rayleigh number, thermal conductivity ratio, heat source length and aspect ratio increased, the fluid flow intensity in the cavity increased. While, it decreased when the walls thickness increased. From the results, it is concluded that case three gives a higher heat transfer enhancement. The obtained results are compared against another published results and a good agreement is found between them.

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Double-diffusive natural convection in a cavity with an inner cylinder wrapped by a porous layer

Thermal Science ◽

10.2298/tsci201112202m ◽

2021 ◽

pp. 202-202

Author(s):

Mourad Moderres ◽

Toufik Benmalek ◽

Aberkan Sofiane ◽

Abderrahmene Ghezal ◽

Said Abboudi ◽

...

Keyword(s):

Thermal Conductivity ◽

Mass Transfer ◽

Natural Convection ◽

Heat And Mass Transfer ◽

Porous Layer ◽

Numerical Study ◽

Thermal Conductivity Ratio ◽

Annular Space ◽

Structure Transition ◽

Double Diffusive

This paper reports a numerical study of double-diffusive natural convection through an annular space delimited by a square cylinder on the outside and a cylindrical cylinder on the inside covered by a porous layer. The Darcy-Brinkmann-Forchheimer is used for modeling flow in both fluid and porous areas. The annular space is partially or completely filled with an isotropic porous medium. A finite volume method, using the Patankar-Spalding technique is used for solving the discretization of the dimensionless equations governing the problem. The effects of simultaneously applied thermal and solutal buoyancy forces on heat and mass transfer are shown in the results for a large range of buoyancy ratios N, Rayleigh number, and thermal conductivity. Streamlines, isotherms, and iso-concentrations are presented to analyze the flow structure transition from mass species dominated to thermal dominated flow. Results show that the buoyancy ratio can change the flow pattern and the increased thermal conductivity ratio can improve heat and mass transfer. A good agreement was obtained between the present results and those published were found.

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