PHASE EQUILIBRIA OF THE SYSTEM METHANE-ETHANE FROM TEMPERATURE SCALING GIBBS ENSEMBLE MONTE CARLO SIMULATION

Abstract

A new technique of temperature scaling method combined with the conventional Gibbs Ensemble Monte Carlo simulation was used to study liquid-vapor phase equilibria of the methane-ethane (CH4-C2H6) system. With this efficient method, a new set of united-atom Lennard-Jones potential parameters for pure C2H6 was found to be more accurate than those of previous models in the prediction of phase equilibria. Using the optimized potentials for liquid simulations (OPLS) potential for CH4 and the potential of this study for C2H6, together with a simple mixing rule, we simulated the equilibrium compositions and densities of the CH4-C2H6 mixtures with accuracy close to experiments. The simulated data are supplements to experiments, and may cover a larger temperature-pressure-composition space than experiments. Compared with some well-established equations of state such as Peng-Robinson equation of state (PR-EQS), the simulated results are found to be closer to experiments, at least in some temperature and pressure ranges.