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A method is presented for calculating the thermodynamic equilibrium state of a multiphase system, by minimising its Gibbs free energy constrained by mass balances. Compared to the other algorithms available in the literature, the method has three main characteristics: - the sets of equations corresponding to the conditions of homogeneous and heterogeneous equilibria are simultaneously solved, - a rigorous mathematical criterion for bringing a new multicomponent phase into the system is demonstrated, - a detailed representation of the multisite solid solutions with constraints known as "the site closure relation" is possible. The code CEQCSY (Chemical Equilibrium in Complex Systems) uses this formalism, and works with the thermodynamic data base from the EQ3/6 code. This choice makes several tests easier when compared with EQ6 : quartz dissolution in water, water-atmospheric air equilibrium, theoretical re-equilibrium of sea-water, hydrothermal alteration of granite including solid solutions. The test results demonstrate the high efficiency and speed of the code CEQCSY, which was developed to improve the coupling with thermal, hydrodynamic or mechanical codes.

Additional information

Authors: LEHMANN J, BRGM-DAM, BP 6009, F-45060 Orléans Cedex (FR);FABRIOL R, BRGM-DAM, BP 6009, F-45060 Orléans Cedex (FR)
Bibliographic Reference: EUR 12299 FR (1989) FS, 30 pp., ECU 5
Availability: (2)
ISBN: ISBN 92-826-0772-0
Record Number: 198911203 / Last updated on: 1994-12-01
Original language: fr
Available languages: fr
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