Aspen Physical Property System - Physical Property Models

For option code = 0 (default), the unsymmetric mixing correction term is in
polynomial form:
For option code = 1, the unsymmetric mixing correction term is in integral
form:
For water the logarithm of the activity coefficient is calculated similarly, as
follows:
Applying:
to equation 3 and using:
Where Nw = moles water, gives:
f(I), the electrostatic term, is expressed as a function of ionic strength I :
I, the ionic strength, is defined as:
2 Thermodynamic Property Models 141
(7)
(6)