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\n\nAbstract:
\nAssociation equations of state (EoS), e.g. Cubic-Plus-Association (CPA), are widely applied in the description of the phase behavior of complex fluid mixtures. However, due to the usual parametrization procedure, in which the parameters are regressed from vapor pressure and liquid density data, these models over-predict the critical pressure and temperature of pure fluids, which results in qualitatively incorrect representations of the pressure-composition phase diagrams of mixtures near the critical point. \nIn order to improve the critical point description of the CPA EOS, we developed a new parametrization procedure, matching the experimental critical pressure and temperature of pure components. The new parameters are compared to the original ones in correlation of phase equilibrium and critical properties of pure components and binary systems. \nDue to the singular asymptotic behavior of fluids near the critical point, we also present a crossover treatment. In this method, the density fluctuations are introduced into a classical EoS, allowing precise representation of the thermodynamic properties in the near critical region.
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\n\nAbstract:
\nAssociation equations of state (EoS), e.g. Cubic-Plus-Association (CPA), are widely applied in the description of the phase behavior of complex fluid mixtures. However, due to the usual parametrization procedure, in which the parameters are regressed from vapor pressure and liquid density data, these models over-predict the critical pressure and temperature of pure fluids, which results in qualitatively incorrect representations of the pressure-composition phase diagrams of mixtures near the critical point. \nIn order to improve the critical point description of the CPA EOS, we developed a new parametrization procedure, matching the experimental critical pressure and temperature of pure components. The new parameters are compared to the original ones in correlation of phase equilibrium and critical properties of pure components and binary systems. \nDue to the singular asymptotic behavior of fluids near the critical point, we also present a crossover treatment. In this method, the density fluctuations are introduced into a classical EoS, allowing precise representation of the thermodynamic properties in the near critical region.