Séminaire du Pole Air: Alex Keïko ( post-doc cereve )

vendredi 06 avril 2001 à 11 heures



Titre:Thermodynamic modelling of incomplete chemical equilibria


Equilibrium thermodynamic models are proved to be efficient in investigation of a number of industrial and natural processes. Nevertheless, their application is usually limited to the cases when a chemically reacting system reaches the state of final equilibrium for the practically observable time. These are high-temperature processes and partitioning of a substance between adjacent phases. A new class of thermodynamic models is being developed. These models are an extention of classical equilibrium approach and survey the whole variety of the states in which a chemical system may appear on its way to the final equilibrium. For an isolated system the set of physically reasonable states is brought about by the relations of material balance and makes up a convex polyhedron. The area of thermodynamically accessible chemical compositions is defined by the conditions of monotonous and continuous change of a thermodynamic function of state along the relaxation trajectory. The models of extreme intermediate states are intended for solution of the following three problems. 1. Determination of the extreme achievable concentrations which may appear in the course of relaxation. 2. Determination of non-thermodynamic restrictions for the course of a process, using empirical data; making out "active" restrictions. 3. Investigation of non-thermodynamic restrictions stiffness and the ways to influence them. Modelling of incomplete equilibria is shown to be fruitful in studies of many technogenic processes, while their applicability to the natural processes is yet to be studied in detail. The existing versions of the models allow one to consider perfect and real gases, pure condensed substances in solid and liquid phase, diluted aqueous solutions of non-electrolytes and electrolytes, and the perfect surface gas.


Alex Keïko