Effect of pore space heterogeneity on the adsorption dynamics in porous media at various convection-diffusion and reaction conditions: A lattice Boltzmann study

Abstract

This paper investigates the influence of pore space heterogeneity on the adsorption dynamics in a single-phase flow. The sensitivity of adsorption dynamics to changes in heterogeneity, which is numerically described by the disorder parameter, is studied in combination with the Peclet number, porosity, adsorption rate constant, and absolute permeability. The focus is on applied results that are useful, for example, in chemical and petroleum engineering. The main findings of this paper were obtained in mathematical modeling based on lattice Boltzmann equations (LBE) for fluid flow (MRT collision scheme) and mass transfer processes (SRT collision scheme). Mass transfer at the adsorbent/adsorbate interface is described using the kinetics law of Langmuir adsorption. Numerical simulations are performed on digital images of the porous structures generated using Monte-Carlo's movement method, which controls the pore space heterogeneity. In this work, special attention is paid to the choice of the relaxation parameter in LBE for mass transfer, which affects the adsorption dynamics. The results of this paper show that heterogeneity significantly affects the dynamics of the adsorbed amount. An increase in the disorder parameter leads to a decrease in the velocity of the concentration front and a slowdown in the adsorption rate. It was found that the sensitivity of the dynamics of adsorption to a change in heterogeneity is maximum at low Peclet numbers. The impact of the disorder on adsorption significantly decreases with an increase in the Peclet number. With the prevalence of the convection mechanism, the adsorption dynamics is practically unaffected by heterogeneity. The effect of heterogeneity is most pronounced at low porosity and decreases significantly with its growth. At high porosity, the influence of heterogeneity on the adsorption dynamics was not revealed. The Damkohler number affects the sensitivity of the adsorption dynamics to changes in pore space heterogeneity. The effect of heterogeneity increases with the increasing intensity of mass transfer. In addition, it was found that absolute permeability does not affect adsorption.