Measurement and prediction of multi-property data of CO2-N2-O2-CH4 mixtures with the “Peng-Robinson + residual Helmholtz energy-based” model

The so-called “Peng-Robinson + residual Helmholtz energy-based mixing rules” equation of state is a promising thermodynamic model that enables the accurate representation of VLE properties of highly non–ideal binary mixtures including the Type-III phase behaviour, according to the classification of van Konynenburg and Scott. So far, the accuracy of this model has been assessed only considering data over which it has been optimized. This publication aims at presenting a multi-property validation of this model over vapour-liquid equilibrium data of the ternaries CO2-N2-O2 and CO2-CH4-N2 and experimental values of enthalpy changes due to mixing of binary mixtures CO2-N2 and CO2-CH4 found in the literature. To integrate the scarce amount of available multicomponent data, this paper also presents new experimental isothermal VLE data for the mixture CO2-N2-O2 at 273 and 233 K, also used along the model validation process. Finally, modelling results obtained from the model “Peng-Robinson + residual Helmholtz energy-based mixing rules” are compared with calculations performed with the widely applied standard Peng-Robinson equation of state.