Heterogenization of supercritical fluids and nonvariant critical equilibria in ternary systems with one volatile component (for water-salt systems as examples)

The phase equilibria in ternary systems with one volatile component and a homogeneous supercritical fluid (SCF) region in one of the binary subsystems (with two critical end-points p and Q) were analyzed. Heterogenization of SCFs, extending from the 2d′ boundary subsystem into a ternary system, starts with monovariant critical phenomena in saturated solutions (l₁ = l₂-s) or (g = l−s), which pass through the extremal parameters of the temperature or composition to form special critical equilibria such as double critical end-points DCEs (l₁ = l₂-s, g = l-s, l₁ = l₂-g) or double homogeneous points DHPs (l₁ = l₂-s ↔ g = l-s). Ternary nonvariant critical points (l₁ = l₂ = g, l₁ = l₂-g-s, and l₁ = g-l₂-s) appear at the intersections of the monovariant critical and noncritical curves.