Generalized negative-flash method for multiphase multicomponent systems

Alireza Iranshahr, D. Voskov, H. A. Tchelepi

Research output: Contribution to journalArticleScientificpeer-review

51 Citations (Scopus)


We describe a generalization of the negative-flash method for computing the equilibrium compositions of systems that can form more than two fluid phases. We show the solution existence and uniqueness of the general Rachford-Rice problem for systems with any number of phases. A bisection based strategy is proposed either as a solution procedure to guarantee convergence, or as a preconditioning step of Newton based methods. A multi-stage negative-flash procedure is developed to identify the state of a multicomponent mixture where the maximum number of phases is arbitrary. The approach should be used in combination with a tie-simplex based modeling framework to provide a general method for phase behavior computations. Challenging numerical examples are presented to demonstrate the accuracy and robustness of the negative-flash approach.

Original languageEnglish
Pages (from-to)272-284
Number of pages13
JournalFluid Phase Equilibria
Issue number2
Publication statusPublished - 25 Dec 2010
Externally publishedYes


  • Arbitrary number of phases
  • Compositional space parameterization
  • Negative flash
  • Thermodynamic phase-state identification
  • Tie-simplex


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