Volume averaging theory (VAT) based modeling for longitudinal mass dispersion in structured porous medium with porous particles

In this study, to investigate the mass transport characteristics in a structured porous medium with porous particles under an interfacial concentration discontinuity, a macroscopic solute transport equation is proposed based on the volume averaging theory. A typical three-dimensional geometry (a body center cubic arrangement of spheres) was chosen as the representative elementary volume. The corresponding closure problem was solved to obtain the longitudinal mass dispersion. Based on the numerical results, a new correlation of the longitudinal mass dispersion for a structured porous medium with porous particles is presented. Through a comparison with the correlation of the longitudinal mass dispersion for a random porous medium, it can be determined that, for a mechanical dispersion, the dependence of a random porous medium and that of a structured porous medium on the Péclet number Pe are linear and quadratic, respectively. Furthermore, it was also determined that for a holdup dispersion, a structured porous medium is less dependent on the ratio of diffusivity of the fluid phase to the diffusivity of the porous particle phase. In addition, it is more dependent on the inverse ratio of the solubilities of the solute in the fluid and in the catalyst particles than in a random porous medium.

Source: Chemical Engineering Research and Design - December 2, 2019 Category: Chemistry Source Type: research