THE STRATEGY OF STUDYING THREE-LIQUID PHASE EQUILIBRIA IN THE CONCENTRATION SPACE OF QUATERNARY MIXTURES

When separating multicomponent heterogeneous mixtures in units consisting of a distillation column and a decanter, a fundamental question is the location of phase separation regions with different numbers of liquid phases in the concentration simplex. A solution of this issue is based on data on the vapor-liquid and liquid-liquid equilibria of the mixture and its components, as well as on the general laws of the formation of the topological structure of phase separation areas. A strategy of studying the three-liquid phase equilibrium area in quaternary mixtures is proposed. The strategy is based on the formula of a topological invariant of the separation region and on the mathematical concept of centroid - the intersection point of three medians. The presence of threeliquid phase areas of separation of open and closed types is shown. They differ in the absence (presence) of region of degeneracy via the critical node.

Determination of vapor—liquid equilibrium diagrams of multicomponent systems

A method for the determination of vapor–liquid phase diagram structure of five-component systems based on the analysis of types and Poincare indexes of singular points of the geometric scan and full structure of the concentration simplex is proposed. Validity of the proposed method was demonstrated by vapor–liquid equilibrium modeling in five-component mixtures: ethanol + water + toluene + butanol + chlorbenzene and acetone + chloroform + ethanol + cyclohexane + water.

Optimization of the aging regime of Al-based alloys

Successful simulation of problems and phenomena related to the changes of the alloys composition is possible by applying simplex plans. The concentration (simplex) triangle application for the design of the optimal regime of Al-5wt%Cu-Pb-Bi alloy aging process is presented in this paper. The iso-lines of the given alloy?s mechanical properties in temperature-aging time coordinates were obtained by applying the mathematical models based of the given aging regimes, and the obtained results of changed properties. Regression polynomial of the fourth degree was used as the mathematical model, whereas the effect of the aging regime has been observed through the changes of tensile strength and contraction. Based on the obtained results, we have come to the conclusion that the simplex lattice method can be successfully applied to a great number of heat treatment aspects when with the increase of the temperature the duration time must be reduced, and vice versa (aging, annealing, homogenizing, etc.).

Relation between the Mass-Centric Coordinates in Multicomponent Salt Systems

An algorithm which allows to define relations between concentration coordinates of subsystems formed in the initial system consisting of simple elements is proposed. The same algorithm gives a possibility to determine the conditions under which the point belongs to the given concentration simplex or complex.

Heterogeneous Design: Concentration Fields Determination with the Unique Crystallization Schemes and Microstructures

ABSTRACTNew approach to calculation of microstructure by means of the one-phase regions borders equations is proposed. Projections of all geometrical elements of phase diagram to the concentration simplex divide it to fields with unique crystallization schemes. All crystallization stages for the given concentration field are simulated and as a result the all elements of microstructure is designed and origin of every phase is shown.