Improved Prediction of Water Properties and Phase Equilibria with a Modified Cubic Plus Association Equation of State

Abstract

One of the major challenges of an equation of state lies in the description of water and aqueous systems. Its abundance and unique properties turn water into one of the most important molecules in the industry. However, because of these peculiar characteristics, its modeling is far more complex than for any other common solvent. In this work, a modified cubic plus association (CPA) model, which includes the correct description of the pure component critical temperature and critical pressure, is expanded to water and its systems. A brief analysis of the predicted water purity properties is conducted, comparing those to a previous version of the model. Results for a group of binary systems, including liquid–liquid equilibria with alkanes and alcohols, highlighting their minima in aqueous solubility, and gas solubility in water/water solubility in gas, are also presented. Finally, ternary and multicomponent systems of water + hydrocarbons and water + polar compound + hydrocarbons are also modeled and discussed.