Molecular dynamics simulation on moisture diffusion process for drying of porous media in nanopores

Abstract

Aiming at the problem that the mechanism of the moisture transfer in the nanopores of porous media has not been researched clearly. In this work, the molecular dynamics model of moisture diffusion in nanopores of porous media was established and the moisture diffusion process was analyzed by the molecular dynamics (MD) method. The Kelvin effect of water diffusion in nanopores of porous media was simulated and the model was validated by drying of potato slices. The results of simulation and verification showed that the molecular dynamics model could simulate and calculate the moisture diffusion coefficient of potato slices well. The maximum relative error of the diffusion coefficient between the simulation and experimental results is 8.6%. During the drying process, the temperature, pore size, wall roughness and the phase area fraction have important effects on the water diffusion in the nanopores. With the increase of the temperature, pore size and phase area fraction, and with the decrease of the wall roughness, the diffusion coefficients of porous media drying increased accordingly.