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OptiSage Slide Show (pdf presentation – 82 pages)
for detailed information on the OptiSage
Module.
The
OptiSage
module is used to generate a consistent set of Gibbs energy
parameters from a given set of experimental data using
known Gibbs energy data from well established phases of
a particular chemical system. The assessor (user of OptiSage)
has to use his best judgement as to which of the known
parameters should remain fixed, which sets of parameters
need refinement in the optimization and which new parameters
have to be introduced, especially when assessing data
for nonideal solutions.
Typical
experimental data include:
The
resulting optimized thermodynamic data are stored in the
private Compound
and Solution
database which can then be accessed by the other modules
(Equilib,
Phase Diagram,
etc.) in the usual way.
For
example, let us look at the optimization of the thermodynamic
data for the binary NaCl – SrCl_{2} liquid phase from
experimental data. The object is to optimize the 4 parameters
A_{1}, A_{3}, B_{1} and B_{3} in the Gibbs energy expression:

GE
= ΔH – TS^{E} 
where 
ΔH
= X_{1}X_{2} (A1) + X_{1}^{2}X_{2} (B_{1}) 
and 
S^{E}
= X_{1}X_{2} (A3) + X_{1}^{2}X_{2} (B_{3}) 
Figs.
1 to 4 show the experimental datasets organized into groups.
Figs.
5 and 7 show Group #5 experimental data being imported
into the calculation. In Fig. 8 these experimental data
are then compared with the results of the optimization.
Notes:
OptiSage
is by no means limited to optimizing binary systems. It
can be used for systems containing any number of components.
Any type of datum which can be calculated by the
Equilib module (eutectic points, vapour
pressures, equilibrium phase amounts, etc.) can be used
as experimental input datum. OptiSage
is a highly complex module, offering maximum flexibility
and scope, that is programmed for the experienced user
– it is an excellent tool for graduate students
taking a course on solution thermodynamics. It offers
a wide variety of input windows and options – Figs.
1 to 8 represent only an introduction to the program in
action.