The formation and growth model of a CO2 hydrate layer based on molecular dynamics

Abstract

AbstractCO2 hydrates are ice‐like substances in which CO2 molecules are encapsulated in water and are known to reduce the rate at which CO2 dissolves in water. It is believed that the thickness of the hydrate film is dominant in the dissolution rate. In this study, we have developed a model that takes into account two factors: the permeation of H2O molecules and the change in film thickness. First, mass transfer coefficients were measured from dissolution experiments of CO2 hydrate, and it was found that existing empirical equations could predict the mass transfer coefficients near the hydrate. Next, molecular dynamics simulations were carried out to determine the self‐diffusion coefficients between CO2. In these calculations, intercage hopping and intracage migration of the molecules were identified based on their migration distances. These results indicate that the kinetic model proposed in this study can reproduce the CO2 hydrate film thickness well.