Molecular dynamics study on water vapor condensation and infiltration characteristics in nanopores with tunable wettability

Water and latent heat can be efficiently recycled from flue gas by using a porous membrane technology, and both the mechanism of water vapor condensation in nanopores and effects of surface properties are critically important to the performance of porous membranes. In this present study, the molecular dynamics simulation was employed to explore the mechanism of water vapor condensation and infiltration in nanopores with tunable surface wettability. Non-equilibrium molecular dynamics simulations of water vapor condensation in a single nanopore with tunable surface wettability were carried out, and then characteristics and dynamic behaviors of water vapor adsorption and condensation in hydrophobic and hydrophilic nanopores were examined in detail. Simulation results indicated that hydrophilic nanopores had high adsorption capacity, and the capillary pressure was the key for the infiltration or rebound progress of condensate in the hydrophobic nanopore. Based on the semi-infiltrated hydrophobic nanopore-liquid water system, furthermore, capillary pressures of hydrophobic nanopores with different sizes and tunable surface wettability were calculated quantitatively by molecular dynamics simulations.