Vapor-Liquid Equilibria of Binary Mixtures Containing Methane, Ethane, and Carbon Dioxide from Molecular Simulation

摘要

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 molecular models were fitted to the experimental vapor pressures and saturated liquid densities in previous papers, which used the same simulation method for the determination of the phase equilibria. For each binary mixture the two unlike interaction parameters were determined from one experimental excess volume and one excess enthalpy. Based on these molecular models the vapor-liquid phase equilibria were calculated for each mixture at three temperatures. Comparison of the pressure-composition data with experimental results shows the high predictive power of this molecular based procedure. This statement is confirmed by additional comparisons of the pressure-composition diagrams and the pressure-density diagrams with results from equations of state.