Prediction of the volumetric and vapor-liquid equilibrium properties of CO2-N2-O2-Ar fluid mixtures with a general Helmholtz equation of state

Abstract

A general equation of state (EOS) explicit in the form of Helmholtz free energy has been developed to predict the pressure-volume-temperature-composition (PVTx) and vapor-liquid equilibrium (VLE) properties of the CO2N2O2-Ar fluid mixtures. The EOS, which uses four mixing parameters, is based on highly accurate EOS for pure CO2, N2, O2 and Ar fluids and contains a simple generalized departure function presented by Lemmon and Jacobsen (1999). Four mixing parameters are fitted from the experimental PVTx and VLE data of binary systems available. Comparison with experimental data available indicates that the EOS can reproduce the PVTx and VLE properties of CO2N2O2-Ar fluid mixtures up to 453 K and 1000 bar within or close to experimental uncertainties. The general EOS can be used to evaluate the change of density and VLE composition from impurities N2, O2 and Ar during the CO2 capture and sequestration process.