Application to mixtures of non-polar fluids of a three-parameter three-fluid corresponding states model based on reference equations of state

In this work a three-parameter three-fluid corresponding states model is applied to the prediction of thermodynamic properties of mixtures of non-polar fluids. Residual thermodynamic properties were calculated by quadratic interpolation between those of three reference fluids, i.e. methane, ethane and carbon dioxide. The properties of these three fluids were obtained from the corresponding multiparameter reference equations of state: the Setzmann and Wagner equation for methane, the Bücker and Wagner equation for ethane and the Span and Wagner equation for carbon dioxide. By this device, the accuracy of the model was quite satisfactory as is demonstrated in this work by comparison with a recent generalised corresponding states model by Sun & Ely. Also, the proposed model showed to be more accurate than the Peng−Ronbison equation of state with volume translation. The percentage average absolute deviations for binary systems were: 0.194 in pρT data, 1.696 in isobaric heat capacities, 0.174 in speeds of sound and 1.322 in bubble-point vapour pressures. Percentage average absolute deviations in pρT data of ternary systems were 0.134 and 0.094 for quaternary systems.