Fluid Phase Equilibria Correlation for Carbon Dioxide +1-Heptanol System with Cubic Equations of State

Abstract

The purpose of this paper is to compare three thermodynamic models to correlate the phase behavior of the highly polar system: carbon dioxide +1-heptanol. These three models rely either on the Peng–Robinson (PR) or on the Soave–Redlich–Kwong (SRK) equations of state and are all coupled with classical van der Waals one-fluid mixing rules. For the two first models, noted SRK/2PCMR and PR/2PCMR, where 2PCMR means two-parameter conventional mixing rule, a single set of temperature-independent binary parameters (kij and lij) was considered. The third model is the well-established PPR78 model also based on the PR equation of state (1978 version). In such a model, lij = 0 but the second binary interaction parameter (kij) is temperature-dependent and predicted by a group-contribution method. All available literature data in a wide range of pressures and temperatures and the global phase equilibrium diagram of the system were calculated with the three aforementioned models. Although the models used are simple, they are able to represent reasonably well the complex phase behavior of the system studied in this work.