SciELO - Scientific Electronic Library Online

vol.44 issue1On hydromagnetic boundary layer flow of nanofluids over a permeable moving surface with Newtonian heatingMathematical modeling for porous media transport in newtonian radiating/chemically reacting fluid over an impulsively-started vertical plate: A finite difference approach author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand




  • Have no cited articlesCited by SciELO

Related links

  • Have no similar articlesSimilars in SciELO


Latin American applied research

Print version ISSN 0327-0793On-line version ISSN 1851-8796


JEREZ, I.J; MUNOZ, F  and  GOMEZ, J.M. Approach to a reliable solution strategy for performing phase equilibrium calculations using MINLP optimization. Lat. Am. appl. res. [online]. 2014, vol.44, n.1, pp.63-70. ISSN 0327-0793.

The objective of this contribution is to propose a reliable strategy to solver the problem of phase equilibrium calculations for non-ideal systems, using the Gibbs free energy minimization. This type of problem, using the Gibbs free energy minimization, is usually formulated as a Mixed Integer Non-Linear Programming (MINLP) Optimization. This optimization problem allows the compositions to be associated with continuous variables, and the presence of phases in the equilibrium to be associated with the integer variables. The solution strategy proposes a bi-level approach. The first level combines a stochastic (Simulated Annealing - SA) and a local deterministic algorithm (Sequential Quadratic Programming - SQP), and solves a Non Linear Programming Problem (NLP). The continuous variables are considered at this level. The second level considers the integer variables. The advantage of this bi-level strategy lies in its easy implementation and in its proven efficiency to locate global optima with acceptable computational load. This article includes the study of the Water-Ethanol-Cyclohexane and Water-Ethanol-Glycerin systems. A comparative analysis was conducted using experimental data reported in published works and theoretical calculations by means of the Gamma-Phi classic method.

Keywords : Phase Equilibrium; Gibbs Free Energy; Non-Linear Optimization.

        · text in English


Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License