Aspen Physical Property System - Physical Property Models

Pitzer, K.S., J.R. Peterson, and L.F. Silvester, "Thermodynamics of
Electrolytes. IX. Rare Earth Chlorides, Nitrates, and Perchlorates, "J. Solution
Chem., Vol. 7, No. 1, (1978), pp. 45-56.
Pitzer, K.S., R.N. Roy, and L.F. Silvester, "Thermodynamics of Electrolytes 7
Sulfuric Acid," J. Am. Chem. Soc., Vol. 99, No. 15, (1977), pp. 4930-4936.
Pitzer, K.S. and L.F. Silvester, J. Solution Chem., Vol. 5, (1976), p. 269.
Silvester, L.F. and K.S. Pitzer, "Thermodynamics of Electrolytes 8 High-
Temperature Properties, Including Enthalpy and Heat Capacity, With
Application to Sodium Chloride," J. Phys. Chem., Vol. 81, No. 19, (1977), pp.
1822-1828.
Polynomial Activity Coefficient
This model represents activity coefficient as an empirical function of
composition and temperature. It is used frequently in metallurgical
applications where multiple liquid and solid solution phases can exist.
The equation is:
Where:
Ai
Bi
Ci
Di
Ei
2 Thermodynamic Property Models 147
=
=
=
=
=
For any component i, the value of the activity coefficient can be fixed:
�i = fi
This model is not part of any property method. To use it:
1. On the Properties | Specifications sheet, specify an activity coefficient
model, such as NRTL.
2. Click the Properties | Property Methods folder.
3. In the Object Manager, click New.
4. In the Create New ID dialog box, enter a name for the new method.
5. In the Base Property Method field, select NRTL.
6. Click the Models tab.
7. Change the Model Name for GAMMA from GMRENON to GMPOLY.
Parameter
Symbol Default MDS Lower Upper Units
Name/Element
Limit Limit
GMPLYP/1 a i1 0 x — — —
GMPLYP/2 a i2 0 x — — —
GMPLYP/3 a i3 0 x — — —