Molecular dynamics simulation on evaporation enhancement of water and aqueous nano-films by the application of alternating electric field

Abstract

In this work, molecular dynamics simulation has been adopted to investigate the influence of square-wave alternating electric field on the evaporation of pure water and aqueous nano-films. The evaporation of the films with 3360 water molecules and 0, 1.11 and 2.18 mol L−1 NaCl on a hot gold (1 0 0) surface was analyzed. The results showed that both the evaporation of water and aqueous films were enhanced by applying the alternating electric field. Compared with the liquid films at the absence of the electric field, the maximum evaporation rates increased 1.71, 1.70 and 1.66 times for water film and aqueous films with 1.11 and 2.18 mol L−1 NaCl for the frequency of 500 GHz, respectively. The reasons were inferred that the water film subjected to the time-varying electrical force resulted in increasing of the rotational and translational kinetic energy of water molecules. Thus applying the alternating electric field accelerated the temperature rise of the water film and enhanced thermal volume expansion of the water film. In addition, the interaction between water molecules became weaker and the water molecules escaped from the water film more easily. The MD simulation also showed that the evaporation enhancement was more significant for the alternating electric field parallel to the films surface than in the perpendicular direction.