M. Gencaslan et M. Keskin, A generalization of the three-state binary gas-liquid lattice models and analysis of their critical lines, PHYSICA A, 293(1-2), 2001, pp. 28-50
The concept of a global phase diagram - a diagram in the space of fluid int
eraction parameters in which regions of similar types of phase behavior are
demarcated - has proved very valuable in both theoretical and experimental
studies of fluid mixtures. This type of work sheds light on the essential
transition mechanism involved in the change of character of the phase diagr
am, such as multi-critical points and double points, and other phenomena of
great practical importance in supercritical fluid extraction processes. Th
e first step in this process is to understand the changes in critical line
structure which underlies these differences. In this work, we study and gen
eralize following compressible binary gas-liquid models; the three-state la
ttice gas, the van der Waals equation for binary mixtures, the Tompa model
for polymer solutions, and the modified version of Tompa model for polymer
mixture solutions. Then, the critical lines of these models are displayed i
n the density-density, P, T and T, x planes. The crossing point, a point at
which two critical lines meet and exchange branches, is also calculated an
alytically. The P, T diagrams are discussed according to Scott and van Kony
nenburg phase diagram classifications. (C) 2001 Elsevier Science B.V. All r
ights reserved.