WANG Xin, LIU Hongwei, LIANG Bing, YANG Xinle, WANG Fang, SUN Weiji, LI Weizhong, SONG Yongchen
Journal of Engineering Thermophysics. 2025, 46(6): 1931-1941.
Methane hydrate, composed of methane molecules and water molecules, represent a clean energy source. The maintenance of hydrate stability under specific temperature and pressure conditions is referred to as the phase equilibrium of hydrate. Capillary pressure significantly influences the phase equilibrium conditions of hydrate, particularly the equilibrium pressure. This study improves existing phase equilibrium pressure models and proposes a novel hydrate decomposition model, incorporating existing hydrate decomposition models. The proposed model is validated through numerical simulations of experimental studies, demonstrating good consistency between numerical simulations and experimental results, thus verifying the reliability of the proposed model. It distinctly highlights the necessity of considering capillary pressure between hydrate and water when investigating methane hydrate decomposition within micropores. The proposed model further elucidates the evolution of methane generation rate, phase distributions, temperature distributions, and equilibrium pressure distributions. The research findings underscore the importance of incorporating capillary pressure between hydrate and water into hydrate decomposition models, as it significantly affects their accuracy. Specifically, neglecting capillary pressure between hydrate and water leads to underestimated cumulative gas production and methane generation rates. The coupling effect of capillary pressure, hydrate decomposition endothermicity, and inter-phase heat transfer influences the distribution of equilibrium pressure, methane generation rate, phase distributions, temperature distributions, and ultimately, the distribution of equilibrium pressure. Capillary pressure promotes an increase in the phase equilibrium pressure of hydrate, enhances the driving force for hydrate decomposition, and facilitates hydrate decomposition. The proposed model contributes to the theoretical foundation for enhancing hydrate decomposition models.
