VAPOR-LIQUID-EQUILIBRIA OF BINARY-MIXTURES CONTAINING METHANE, ETHANE, AND CARBON-DIOXIDE FROM MOLECULAR SIMULATION

The NpT+test particle method is used in order to predict vapor-liquid equilibria of the mixtures methane+ethane, methane+carbon dioxide, and carbon dioxide+ethane by molecular simulations. The pure-component mo lecular models were fitted to the experimental vapor pressures and sat urated liquid densities in previous papers, which used the same simula tion method Cor the determination of the phase equilibria. For each bi nary mixture thr two unlike interaction parameters were determined fro m one experimental excess volume and one excess enthalpy. Based on the se molecular models the vapor-liquid phase equilibria were calculated for each mixture at three temperatures. Comparison of the pressure-com position data with experimental results shows the high predictive powe r of this molecular based procedure. This statement is confirmed by ad ditional comparisons of the pressure-composition diagrams and the pres sure-density diagrams with results from equations of state.