Solubility measurements for the CH4 + C2H6 + H2O system under hydrate-liquid-vapour equilibrium

• Methane and ethane experimental solubility at H-Lw-V equilibrium were obtained.
• Effects of temperature and pressure on solubility trends can be observed.
• Structure change between sI and sII affected solubility trends.

Liquid and gas mole fractions were obtained at three-phase H-Lw-V equilibrium for the CH4 + C2H6 + H2O system at experimental conditions ranging from 275.1 to 279.1 K and 0.76–2.87 MPa. To ensure the system reached equilibrium while sampling, gaseous mole fractions were compared to literature values and were found to correspond. The solubility of both methane and ethane along isotherms is reported at various pressures. The effect of thermodynamic parameters on equilibrium liquid mole fractions can be observed. Additionally, structure transitions between sI and sII were found to influence solubility trends. While scarce in literature, experimentally obtained liquid mole fractions at three-phase equilibrium conditions provide further insights into multicomponent gas hydrate system properties and establish a solid foundation for future studies.