The kinetic modeling of methane hydrate growth by using molecular dynamic simulations

In the present work, the molecular dynamic simulation was applied for studying the kinetics of methane hydrate growth. Several parameters such as the changes of potential energy, the MSD of molecules, the number of methane molecules near the solid/liquid interface and the position of liquid/solid interfaces with time were considered. The results showed that the potential energy and MSD of molecules in the layers near the interfaces significantly decreases implying that the growth proceeds in these layers. The maximum rate of growth or migration of methane molecules to the interfaces is observed around 2 ns. Moreover, a kinetics model was considered to predict hydrate growth kinetics. It is based on the irreversible and non-equilibrium thermodynamics and the concept of the thermodynamic natural path. The proposed model is a two-parametric model that one parameter was estimated to be a nearly constant value in the range from -1.05 to 1.46, but another one is a kinetic parameter dependent on the operational conditions. The model can well predict the entire process of hydrate formation, since the affinity, as a driving force of the process, shows that the hydrate formation is a process proceeding on a natural path. (C) 2019 Published by Elsevier Ltd.