Handbook of Solvents - George Wypych - ChemTech - Ventech!

1426 Aydin K. Sunol and Sermin G. Sunol
Figure 21.1.9 The crossover pressure and retrograde behavior.
Figure 21.1.10. A high pressure fluid phase equilibrium measurement system.
21.1.2.1.1 Experimental methods
There are two basic approaches to experimental
determination of the high-pressure
phase behavior of a system, synthetic and
analytic. In the synthetic approach, phase
boundaries of a fixed (known) composition
system are observed, usually visually, in a
cell with sight windows, by manipulation of
the system pressure and temperature.
In the analytical approach, the components
are equilibrated and the compositions
of the co-existing phases are determined either
through sampling and off-line analysis
or on-line spectroscopic techniques. A typical
system for determination of vapor/liquid/liquid
phase behavior is shown in Figure
21.1.10. The system is a double re-circulation
variable volume system. A dynamic
variant of this method is for the determination
of the solubility of solids in a supercritical
fluid. The stationary solid phase is
contacted with a continuous supply of