Numerical study of mass transfer and desorption behaviors in deformable porous media using a coupling lattice Boltzmann model.

The aim of this paper is to investigate the pore-scale mass transfer and desorption behaviors in deformable porous media using a coupling immersed boundary method (IBM)-lattice Boltzmann (LB) scheme. In this numerical model, a three-dimensional multiple-relaxation-time LB model is used to simulate fluid flow in porous media consisting of movable rigid adsorbent particles. To consider the effect of dynamic deformation of a porous structure, an improved immersed boundary method scheme is introduced to describe the fluid-structure interaction at the interface between the carrier gas and moving absorbent particles. Moreover, a LB model for the convection diffusion equation is adopted to consider the mass transfer of adsorbate into the macropores and micropores of the porous adsorbent. This coupled IBM-LB model is used to illustrate the mass transfer and desorption processes in shrinkage deformation of the porous structure caused by the movement of rigid adsorbent particles along different directions. At the initial time, these adsorbent particles have a saturation adsorption amount, and the adsorbate in the macropores has the uniform concentration distribution. The numerical results show that the time history curve of the adsorbate concentration in the macropores can be divided into an upturn period and a downturn period during the dynamic desorption process. In the concentration upturn period governed by Langmuir adsorption kinetics, the shrinkage deformation of the porous structure along different directions has no remarkable effect on the mass transfer and desorption behaviors. However, during the concentration downturn period governed by the mass transfer rate of the adsorbate, the shrinkage deformation of the porous structure obviously decreases the efficiency of the desorption process. In addition, the roles of the deformation direction and morphology of the porous media in the desorption process are illustrated in this work.