چكيده به لاتين
Over the past recent decades, modeling transport phenomena in porous media has been progressed significantly. Changes on the geometry of the pores in the porous medium, causes significant impacts on transport phenomena such as fluid flow and heat transfer. So, considering the geometric details in numerical simulations of transport phenomena is necessary which is often mentioned in the literature as micro-scale transport simulation. However, it is generally not possible to simulate the whole problem in micro-scale. Micro-scale simulation of a part of the whole geometry and calculating the parameters which will be used in macro-simulation is an approach to solve this limitation.
In this study, numerical simulation of permeability and thermal conduction in a fibrous porous medium used in radiative catalytic heaters have been studied in micro-scale. By using the structural properties obtained from microscopic imaging, the geometry of the porous medium was rebuilt in the form of a code and fluid flow and thermal conduction of this geometry were simulated. According to Brinkman screening length and independence of obtained results from the computational cell size, the computational domain was determined in such a way that be a suitable representative of the fibrous porous medium. To exclude the inertial effects, fluid flow was considered in the range of Reynolds less than unit. After studying the independence of results from mesh numbers, and model validation with results and correlations in literature, the influence of geometrical parameters of the porous medium such as solid volume fraction, fibers diameters and their orientations in space on permeability and effective thermal conductivity coefficients were investigated.
According to the obtained results, by increasing the solid volume fraction, permeability decreases but thermal conductivity coefficient increases. Also, as the angle between flow (either fluid or heat flow) direction and fibers increases, permeability and effective thermal conductivity decreases. Increasing fibers diameters increases the permeability but has no significant effect on effective thermal conductivity coefficient because of the consistency of the solid volume fraction.
Keywords: fibrous porous medium, micro-scale simulation, geometry generation, permeability, thermal conduction.
