Modelling the High Pressure Phase Equilibria of Carbon Dioxide ? Triglyceride Systems: Parameterization

M. CISMONDI; J. MOLLERUP; E.A. BRIGNOLE; M. ZABALOY

Ischia, Italy

Conferencia; Eighth Conference on Supercritical Fluids and Their Applications; 2006

The group contribution equation of state (GC-EOS) has been used in several works to correlate or predict the high-pressure phase equilibria of a variety of systems. Nevertheless, quantitative and even qualitative disagreement among predictions and experimental data has been detected in mixtures of CO2 with heavy compounds, such as triglycerides, when operating at high pressure. In the present work, we study the influence on calculated critical lines and solubilities (Pxy diagrams) of the group-based interaction parameters kij, for the interactions of CO2 with both, the triglyceride (TG) group and the paraffinic groups. Based on such study, we propose a parameterization procedure that improves upon the conventional parameter regression practice. For the case of the non-randomness parameter, we use a universal positive value, more consistent with its physical meaning.