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Multiphase Equilibria Calculation by Direct Minimization of Gibbs Free Energy Using the Tunnelling Global Optimization Method

Domenii publicaţii > Stiinte ingineresti + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: D.V. Nichita, S. Gomez, E. Luna-Ortiz

Editorial: Petroleum Society, Journal of Canadian Petroleum Technology, 43 (5), p. 13-16, 2004.


In this paper, we advocate the use of the Tunnelling global
optimization method for phase stability analysis and for multiphase
equilibria calculations. The method had been successfully
used for solving a variety of phase-equilibrium problems. The
Tunnelling method has two steps. First, a minimum (which may
not be the putative global minimum) of the objective function is
found by a local bounded minimization algorithm. In a second
step, the method checks for global optimality. If the minimum
found in the first step is only a local minimum, a feasible initial
estimate for a new minimization is generated in another valley
of the objective function.
Cubic equations of state are used, but any thermodynamic
model for the Gibbs free energy can be used (the method being
model-independent). The proposed method has proven to be an
efficient and reliable tool for multiphase equilibrium calculation.

Cuvinte cheie: Multiphase equilibrium, stability analysis, global optimization, Tunneling, equation of state