Characterization of the heterogeneous region of computed solid-fluid equilibrium isopleths

SABRINA BELÉN RODRIGUEZ REARTES; MARCELO SANTIAGO ZABALOY

Alicante

Congreso; X IBEROAMERICAN CONFERENCE ON PHASE EQUILIBRIA AND FLUID PROPERTIES FOR PROCESS DESIGN; 2015

Chemical Enginnering Department. University of Alicante (Spain)

The phase behavior of binary systems made of CO2 and an organic compound having a relatively high molecular weight is of interest in varied applications, e.g, Refs [1,3]. Within the ranges of conditions of interest, these systems may present fluid-fluid (FFE), solid-fluid (SFE), liquid-liquid-vapor (LLVE) and solid-fluid-fluid (SFFE) equilibria. Typically, transition pressures (temperatures) are measured at set temperature (pressure), and set overall composition (isopleths), through the synthetic method, covering a temperature (pressure) range. The result is a set of measured segments of isopleth phase envelopes, eventually together with segments of three-phase equilibrium lines in the pressure-temperature space. Appropriate models for these complex systems may be useful to interpolate and extrapolate experimental information, and to study possible patterns of phase behavior. One such model has ben used in Refs [1] to [3]. In particular, in Ref [1] the calculated isopleths included the phase envelope and the appropriate segments of a SFFE line, for the system carbon dioxide + medroxyprogesterone acetate; while in Ref [3], for the sytem CO2+Mitotane, only phase envelopes were computed. In both cases [1,3], the phase envelopes included SFE and FFE segments. The systems in Refs [1] and [3] present retrograde behavior. A more complete characterization of the contribution of the SFE to isopleths can be done by computing lines of constant solidified fraction. Thus, the objective of the present work is to study the heterogeneous region of computed solid-sluid equilibrium isopleths of binary aysmmetric systems, by resorting to calculated constant solidfied-fraction curves.