Bubble dynamics modeling with a chemical reaction for methane pyrolysis in molten tin via computational fluid dynamics

Previous numerical studies on methane pyrolysis in molten media have primarily employed one-dimensional models or have neglected reaction kinetics in multi-dimensional models, limiting their ability to accurately capture bubble behavior and methane conversion. This study presents a two-dimensional (2D), multiphase computational fluid dynamics (CFD) investigation of methane pyrolysis in molten tin, integrating both chemical reactions and hydrodynamics to enhance predictive accuracy. The model's reliability is validated using experimental data and the empirical model, achieving an average absolute difference of 1.2 % in methane conversion rate and a mean error of less than 4 % in bubble rising velocity. A comparative analysis of bubble behavior with and without chemical reactions reveals the significant impact of pyrolysis reactions on bubble dynamics, including an approximately 30 % increase in bubble volume due to methane decomposition and hydrogen production. This study also reveals the effects of bubble size variations on rising velocity, residence time, and methane conversion rates. Notably, the residence time does not exhibit a linear correlation with bubble size, but is clearly linked to methane conversion. These findings highlight the importance of modeling bubble dynamics coupled with methane conversion reactions in numerical studies to gain deeper insights into bubble behavior and optimize reactor design for methane pyrolysis.