A new model for hydrodynamics and mass transfer of hydrated bubble rising in deep water

- A new model was developed to predict hydrated bubble rising in deep water.
- Synergy between hydrate shell growth, bubble hydrodynamics, and mass transfer was considered.
- A correlation of mass transfer coefficient for hydrated bubble dissolution was proposed.
- The accuracy of the model was verified by literature experimental data.
- The rising process of methane bubble in deep water was investigated.

Hydrate shell growth characteristics have a significant influence on the migration process of a gas bubble rising in deep water, which has raised concerns across of broad range of environmental fields including marine chemistry, global warming, and ocean carbon dioxide disposal. In this work, a new coupled model of the behaviors of hydrated bubbles is developed. This model considers the bubble hydrodynamics, gas dissolution, hydrate nucleation time, and dynamic growth of the hydrate shell. In combination with published experimental data, the present model proposes new mass transfer correlations involving hydrated bubble dissolution and water permeation across the hydrate shell to describe the effects of the bubble interface and the hydrate shell structure on the mass transfer processes. Using the proposed model, the rising process of methane bubbles released at depths of 1000-2000 m in the California coast is simulated. The simulated results show that the hydrate nucleation time decreases rapidly as the water depth increases. Furthermore, the formed hydrate shell can reduce the gas bubble rising velocity and shrinkage rate, because it alters the mechanical force balance and gas dissolution rate. This work adds further insights into quantitatively characterizing the upward migration and mass transfer of a hydrated bubble in deep water.