Temperature-pressure coupling effects on nitrogen solubility in liquid methane and associated engineering risks

This study systematically analyses the solubility of nitrogen in liquid methane by comparing the Hildebrand solubility parameter-based empirical model and the gas-liquid equilibrium experimental data-driven predictive model. The applicability and accuracy of both methods are evaluated. The results indicate that under typical operating conditions, the solubility of nitrogen in liquid methane is significantly high, decreasing with rising temperature and increasing with nitrogen partial pressure. This phenomenon suggests that nitrogen, as a pressurant gas, poses a substantial risk of tank pressure instability due to its high dissolution rate, necessitating the selection of low-solubility alternatives such as helium. The research provides a theoretical foundation for optimizing pressurant gas selection in liquid methane fuel systems and offers critical insights for enhancing system safety and reliability.