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Aspen Physical Property System - Physical Property Models

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Wagner Interaction Parameter<br />

The Wagner Interaction Parameter model calculates activity coefficients. This<br />

model is used for dilute solutions in metallurgical applications.<br />

The relative activity coefficient with respect to the reference activity<br />

coefficient of a solute i (in a mixture of solutes i, j, and l and solvent A) is:<br />

Where:<br />

The parameter �i ref is the reference activity coefficient of solute i:<br />

kij is a binary parameter:<br />

For any component i, the value of the activity coefficient can be fixed:<br />

�i = gi<br />

This model is recommended for dilute solutions.<br />

Parameter Name/<br />

Element<br />

2 Thermodynamic <strong>Property</strong> <strong>Models</strong> 179<br />

Symbol Default MDS Lower<br />

Limit<br />

Upper<br />

Limit<br />

Units<br />

GMWIPR/1 a i 0 x — — TEMPERATURE<br />

GMWIPR/2 b i 0 x — — —<br />

GMWIPR/3 c i 0 x — — —<br />

GMWIPB/1 d ij 0 x — — TEMPERATURE<br />

GMWIPB/2 e ij 0 x — — —<br />

GMWIPB/3 f ij 0 x — — —<br />

GMWIPO g i — x — — —<br />

GMWIPS — 0 x — — —<br />

GMWIPS is used to identify the solvent component. You must set GMWIPS to<br />

1.0 for the solvent component. This model allows only one solvent.<br />

References<br />

A.D. Pelton and C. W. Bale, "A Modified Interaction Parameter Formalism for<br />

Non-Dilute Solutions," Metallurgical Transactions A, Vol. 17A, (July 1986),<br />

p. 1211.<br />

Wilson Activity Coefficient Model<br />

The Wilson model calculates liquid activity coefficients for the following<br />

property methods: WILSON, WILS2, WILS-HOC, WILS-NTH, WILS-RK, WILS-

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