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Aspen Physical Property System - Physical Property Models

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where YC is a cationic charge composition fraction and YA is an anionic charge<br />

composition fraction; they are defined as follows:<br />

Notice that electrolyte here is meant to represent an ion-pair composed of a<br />

cationic component and an anionic component in the solutions. The result is<br />

that electrolytes are generated from all possible combinations of ions in the<br />

solution; each generated electrolyte is not necessarily associated with an ionpair<br />

through the dissociation.<br />

Option Codes in NRTL-SAC<br />

Three option codes are available for NRTL-SAC to select the reference state<br />

and to optionally exclude the Flory-Huggins and long-range interaction terms:<br />

Option CodeValue Meaning<br />

1 0 Reference state for ions is unsymmetric: infinite dilution in<br />

aqueous solution (default)<br />

118 2 Thermodynamic <strong>Property</strong> <strong>Models</strong><br />

2 Reference state for ions is symmetric: pure fused salts<br />

2 0 Flory-Huggins term included (default)<br />

1 Flory-Huggins term removed<br />

3 0 Long-range interaction term included (default)<br />

References<br />

1 Long-range interaction term removed<br />

C.-C. Chen and Y. Song, "Extension of Nonrandom Two-Liquid Segment<br />

Activity Coefficient Model for Electrolytes," Ind. Eng. Chem. Res., 2005, 44,<br />

8909.<br />

Y. Song and C.-C. Chen, "Symmetric Nonrandom Two-Liquid Segment Activity<br />

Coefficient Model for Electrolytes," Ind. Eng. Chem. Res., 2009, 48, 5522.

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