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. The capabilities and limitations of CPA are discussed and suggestions for extension of the model to systems not covered in this work are provided.
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. The capabilities and limitations of CPA are discussed and suggestions for extension of the model to systems not covered in this work are provided.
“…SLE diagrams for the n-paraffin with n-alkanol mixtures are of great importance to fat, cosmetic, and oil technology and research. Many authors (Plesnar et al, 1990;Doman ´ska and Doman ´ski, 1991;Huyskens and Seghers, 1994) have published extensive solubility data. Solubilities of some normal paraffins (C 18 -C 28 ) in tert-butyl alcohol have been measured by Doman ´ska and Gonza ´lez (1998) for improving the thermodynamic characterization of such mixtures in terms of the DISQUAC group contribution model.…”
The solid−liquid equilibrium (SLE) has been measured above 280 K for eight mixtures of n-alkanes
(octadecane, eicosane, docosane, tetracosane, pentacosane, hexacosane, heptacosane, octacosane) with
methyl 1,1-dimethylethyl ether (MTBE). Experimental results of solubility are compared with values
calculated by means of the Wilson, UNIQUAC, and NRTL equations utilizing parameters taken from
the SLE. The existence of a solid−solid first-order phase transition in hydrocarbons has been taken into
consideration in the solubility calculations. The solubility of hydrocarbons in branched chain ethers is
lower than that in n-alkanes but higher than that in cycloalkanes, branched alkanes, 1-alcohols, and
tert-alcohols. The best correlation of the solubility data has been obtained by the NRTL equation, where
the average root-mean-square deviation of the solubility temperatures is 0.46 K. The liquid−liquid
equilibrium (LLE) has been measured between 300 and 360 K for binary mixtures of water with ethyl
1,1-dimethylethyl ether, methyl 1,1-dimethylpropyl ether, and ethyl 1,1-dimethylpropyl ether. The
solubility of water in branched chain ether increases with increasing temperature, whereas the solubility
of ether in water is decreasing up to 330 K and at the higher temperatures is slightly increasing. The
excess molar volumes
have been measured at the temperatures 298.15 K and 308.15 K for binary
mixtures of hexane, octane, decane, dodecane, tetradecane, hexadecane, cyclohexane, and 1-heptyne with
ethyl 1,1-dimethylpropyl ether. The excess molar volumes of all mixtures except for 1-heptyne are positive
over the whole composition range. The experimental results have been correlated with the Redlich−Kister polynomial and compared with the results predicted from Prigogine−Flory−Patterson theory. The
interchange parameter X
12, which minimized
experimental data, was adjusted and then used to
predict the heat of mixing.
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