CPA (Cubic-Plus-Association) is an equation of state that is based on a combination of the Soave−Redlich−Kwong (SRK) equation with the association term of the Wertheim theory. The development of CPA started in 1995 as a research project funded by Shell (Amsterdam), and the model was first published in 1996. Since then, it has been successfully applied to a variety of complex phase equilibria, including mixtures containing alcohols, glycols, organic acids, water, and hydrocarbons. Focus has been placed on cases of industrial importance, e.g., systems with gas-hydrate inhibitors (methanol, glycols), glycol regeneration and gas dehydration units, oxygenate additives in gasoline, alcohol separation, etc. This manuscript, which is the first of a series of two papers, offers a review of previous applications and illustrates current focus areas related to the estimation of pure compound parameters, alcohol−hydrocarbon vapor−liquid equilibria (VLE) and solid−liquid equilibria (SLE), as well as aqueous systems. Th...

Ten Years with the CPA (Cubic-Plus-Association) Equation of State. Part 1. Pure Compounds and Self-Associating Systems

High-pressure fluid-phase equilibria: Experimental methods and systems investigated (1988–1993)

Phase equilibria for petroleum reservoir fluids containing water and aqueous methanol solutions: Experimental measurements and modelling using the CPA equation of state

Perturbed chain-statistical associating fluid theory (PC-SAFT) was extended rigorously to polar fluids based on the theory of Stell and co-workers [Mol. Phys. 1977, 33, 987]. The new PC-PSAFT was simplified to truncated PC-PSAFT (tPC-PSAFT) so that it can be practical for real polar fluid thermodynamic calculations. In this work, tPC-PSAFT is generalized to multicomponent mixtures and evaluated for a wide range of highly nonideal polar mixtures. Binary and ternary mixtures of dipolar, quadrupolar, and/or associating fluids are examined. Vapor−liquid and liquid−liquid equilibria at low and high pressures are calculated. Comparisons against PC-SAFT calculations are made. It is shown that tPC-PSAFT is an accurate model for polar fluid mixture phase equilibria.

Evaluation of the Truncated Perturbed Chain-Polar Statistical Associating Fluid Theory for Complex Mixture Fluid Phase Equilibria

Modelling LLE and VLE of methanol + n-alkane series using GC-PC-SAFT with a group contribution kij

Vapor and liquid equilibrium phase compositions were determined at 310.7, 352.2, 393.0 and 474.3 K for the propane-methanol system and at 469.9 K for the n-butane–methanol system. Measurements were made at pressures from the vapor pressure of the less volatile component to the maximum pressure where two phases coexisted either as an azeo-trope or at the critical condition, depending on the system. Azeotropic behavior was observed at 310.7 and 352.2 K for the propane-methanol system. Equilibrium ratios were calculated at each temperature from the phase composition data. The temperature dependence of the azeotrope pressure and of the corresponding azeotrope composition was expressed analytically.

C.-J. Chen

Papers

The equilibrium phase properties of the propane‐methanol and n‐Butane‐methanol binary systems