Implementation of SAFT + Cubic and PC-SAFT for comprehensive description of thermodynamic properties of n-octane and its mixtures

The paucity of the available sound velocity and other auxiliary property data on supercritical mixtures restricts the comprehensive examination of the EoS models to just a few systems. In the current study pure n-octane(2) and its several mixtures such as methane(1)–n-octane(2) and nitrogen(1)–n-octane are considered. It is demonstrated that the recently proposed SAFT + Cubic Equation of State (EoS) has a doubtless advantage over the popular PC-SAFT model in predicting the elevated pressure densities. In addition, SAFT + Cubic appears as a robust estimator of sound velocities and compressibilities both at low and high pressures, which is not a case of PC-SAFT. Although SAFT + Cubic is capable of only rough estimation of heat capacities of pure n-octane, its results are closer to the experimental data than the predictions of PC-SAFT. Additional research should be performed for drawing grounded conclusions concerning the accuracy of both equations in modeling phase equilibria.