Diffusion-based modeling of film growth of hydrates on gas-liquid interfaces

Abstract

Formation of gas hydrates occurs in three stages: nucleation, film growth, and bulk growth. As per past literature, the rate of film growth (on gas-liquid interface) depends on heat transfer from the vicinity of the film front to the surrounding medium. We present analyses to show that heat transfer is not a significant factor in film growth, as previously believed. We then present an alternative theory for film growth, which considers film growth as gas diffusion limited. We note that gas diffusion through hydrates is a limiting phenomena for bulk growth; we presently show that diffusion from the gas phase is the limiting phenomena for film growth as well. This fundamentals-based analytical model does not need the significant assumptions invoked in previous studies and relies on only one fitting parameter. Importantly, the model shows excellent agreement with experimental results on film growth of hydrates from pure gases and mixtures of gases.