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Experimental Methods, Results and Discussion
phases, for instance near or even at critical points. Since no sampling is necessary, the
experimental equipment can be rather inexpensive and the experimental procedure is
usually easy and quick. For multicomponent systems, experiments with synthetic methods
yield less information than with analytical methods. Therefore, synthetic methods are
rarely used for ternary systems (Costa et al., 1996). Also, the precise detection of incipient
phase formation especially for dew point is difficult and it causes inaccuracies in P and T.
The detection of the equilibrium point can be done by visual observation of the resulting
turbidity/meniscus that characterize the appearance of a new phase, in the case of nonisooptic
systems, or by any other physical properties that can detect phase transitions as
transmitted X-rays (Abedi et al. 1999), relative dielectric permittivity (Goodwin et al.,
1997) or ultrasonic speed apparatus (Takagi et al., 1999). If the total volume of a variablevolume
cell can be measured accurately, the appearance of a new phase can be obtained
from PVT measurements taking advantage of the pronounced changes that appear on this
properties that occurs at the phase boundary (Roy et al., 1997; Warowny, 1994).
Numerous binary and multicomponent systems have been studied using one of the
high-pressure methods mentioned above. The choice of the best method depends
essentially on the properties of the system and on the conditions to be studied. In spite of
the amount of work done in this field, data relating solubility of carbon dioxide in
fluorinated systems is almost inexistent in the open literature. In fact, data was found only
for the CO2/perfluoro-n-hexane system, which was studied by two authors. Table II.17
resumes the methods and experimental conditions used by the authors to perform their
measurements.
Table II.17. Compilation of the references reporting experimental solubility data for
CO2/perfluorocabon systems
System Method T range (K) P range (MPa) Reference
CO2/ C6F14 Analytical 314.65 and 353.25 2 - 10 Iezzi et al., 1989
CO2/ C6F14 Synthetic 313 1 - 7 Lazzaroni et al., 2005
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