Gas and Liquid Transfer in Narrow Pores

A microhydrodynamic approach is formulated to describe the molecular flows in micro- and mesoporous systems, including the region of capillary phenomena, where one needs a single set of equations characterizing the flows of both dense gases and liquids. The set of equations of the transfer of dense fluids in narrow pores is closed by using the simplest molecular model, specifically, the lattice gas model, which describes the behavior of fluids over wide ranges of concentrations (from the gas to the liquid state) and temperatures, including the critical region. This model takes into account the volume of molecules and the intermolecular interactions in a quasi-chemical approximation, which retains short-range order correlations. The model reflects the strong anisotropy of the molecular distributions along a normal to the pore wall (because of the adsorption forces) and along the pore axis if there is capillary condensation. The derived set of equations is a set of finite-difference equations in increments of coordinates (instead of derivatives). The dissipative coefficients have a nonlocal anisotropic character. The equations of the transfer in near-wall cells and the prospects of the microhydrodynamic approach are discussed.