Анализ фазопереходных процессов на основе линейных феноменологических отношений

Abstract

ANALYSIS OF PHASE TRANSITION PROCESS ON THE BASIS OF LINEAR PHENOMENOLOGICAL RELATIONS

B. Draganov, V. Demchenko

The purpose of research - to develop a method for studying the processes teplomasloobmena in multicomponent media with phase transitions by linear nonequilibrium thermodynamics.

Materials and methods of research. W. Gibbs considered a heterogeneous system consisting of different materials with specific masses.

At the thermodynamic analysis of sorption systems often differ adsorption in the surface layer (macroporous sorbents) and in the volume of micropores (microporous sorbents). The sorption properties of the phases of both types has a deep analogy is fundamentally different from conventional bulk phases: the pressure in the plane of the surface layer and at least in some areas in the bulk phase sorption otlichaetsyaot total pressure in the system. Therefore, in both cases, the fundamental equations must contain a term which takes into account the additional work of formation of the surface layer.

The volume of the sorption components of the solution can generally depend on its composition, but it is possible without violating the thermodynamic consideration of the severity of the hard model to accept the sorption solution.

The results of research. Noteworthy is the task of the analysis of phase transitions from a position of nonequilibrium thermodynamics.

For states close to equilibrium between the fluxes and forces used linear Onsager formulation of a uniform status.

The importance of the Onsager relations lies in their community. They withstood numerous experimental tests. The validity of the Onsager relations for the first time shown that nonequilibrium thermodynamics as well as equilibrium thermodynamics, resulting in the overall results do not depend on the choice of a particular molecular model.

Onsager principle is applicable to the analysis of more complex structures, for example in the case of conjugate forces and flows. The paper considers the system consisting of the two forces, and mating with them flow.

The thermodynamics of irreversible processes in relation to the system with the following principles are used by small non-equilibrium:

1. linearity principle, according to which the thermodynamic flows are linear dependence on the thermodynamic forces:

2. The principle of symmetry Curie, according to which the flow and thermodynamic forces of various tensor dimensionality can not be related to each other. This principle is based on the property of the isotropic mixture. The non-equilibrium thermodynamics of this principle introduced by Prigogine.

3. The principle of reciprocity of Onsager, according to which the phenomenological coefficients for cross-effects satisfy the symmetry condition.

With regard to the applicability of Gibbs identity for nonequilibrium processes in a continuous thermodynamic system, we note the following. Under the principle of quasi-local balance (basic postulates of nonequilibrium thermodynamics), the entire system can be divided into sufficiently small macroscopic regions, each of which can be considered as an equilibrium (or rather quasi-equilibrium) thermodynamic system.

It should also be noted that the hypothesis of local equilibrium the environment equivalent to the suggestion of justice not only the Gibbs relation, but all the other thermodynamic relations for infinitesimal regions of nonequilibrium systems.

Сonclusions

Analysis of phase transitions, including the phenomenon of adsorption should be carried out by methods of nonequilibrium thermodynamics. Derivation of generalized relations on the basis of phenomenological relations Onsager allows to obtain important algebraic relations that decision is easy. These solutions are valid for a wide range of media, for example, multi-component gas mixtures. A characteristic of the irreversibility of non-equilibrium environments will happen entropy production.