Aspen Physical Property System - Physical Property Models

�I *PDH = Pitzer-Debye-Hückel term
�I *FH = Flory-Huggins term
2 Thermodynamic Property Models 111
= Aqueous-phase infinite-dilution reference state
�i = Activity coefficient of conceptual segment i
rI = Total segment number of component I
xI = Mole fraction of component I
rI,i = Number of conceptual segment i containing in component I
xi = Segment mole fraction of conceptual segment i in mixtures
�ij = NRTL binary non-randomness factor parameter for
conceptual segments
�ij = NRTL binary interaction energy parameter for conceptual
segments
A� = Debye-Hückel parameter
� = Closest approach parameter, 14.9
Ix = Ionic strength (segment mole fraction scale)
= Average solvent molecular weight, g/mol
= Average solvent density, g/cm 3
NA = Avogadro’s number
Qe = Absolute electronic charge
= Average solvent dielectric constant
�w = Water dielectric constant
rc = Born radius of cationic segment
ra = Born radius of anionic segment
NRTL binary parameters for conceptual segments
The NRTL binary parameters between conceptual molecular segments in are
determined by available VLE and LLE data between reference molecules
defined in NRTLSAC.
Segment (1) x x y- y+ x
Segment (2) y- z z z y+
� 12
� 21
� 12 = � 21
1.643 6.547 -2.000 2.000 1.643
1.834 10.949 1.787 1.787 1.834
0.2 0.2 0.3 0.3 0.2
NaCl is used as the reference electrolyte for the conceptual electrolyte
segment e. The NRTL binary parameters between conceptual molecular