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Thermodynamic modeling of low-pressure vapor-liquid equilibrium of binary systems via metaheuristic algorithms
Juan A. Lazzús and Pedro Vega
A thermodynamic model is applied to estimate the vapor-liquid equilibrium (VLE) for binary systems at low pressure. This model involves the Peng‒Robinson equation of state (PR) and Wong‒Sandler mixing rules (WS) as well as the van Laar model for excess Gibbs free energy (VL). The main problem consists of determining the interaction parameters included in the PR-WS-VL model by using available data of vapor-liquid phase equilibria of fifteen isothermal systems. Subsequently, a metaheuristic algorithm based on particle swarm optimization (PSO) plus ant colony optimization (ACO) is implemented for minimizing the difference between calculated and experimental bubble pressures and for modeling the concentration in the vapor phase of the congener in each system. The results thus obtained confirm the PSO-ACO algorithm as a superior tool for the correlation and prediction of vapor-liquid equilibrium on isothermal systems, applicable with high performance and accuracy for optimizing different thermodynamic models.
Keywords: Vapor-liquid equilibrium; Alcoholic mixtures; Equation of state; Peng‒Robinson equation; Wong‒Sandler mixing rules; Swarm intelligence.