FactSage Modules
The module

Click on Download 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 non-ideal solutions.

Typical experimental data include:

  • phase diagram data: transitions temperatures and pressures as well as amount and composition of the phases at equilibrium
  • calorimetric data: enthalpies of formation or phase transformation, enthalpies of mixing, heat contents and heat capacity measurements
  • partial Gibbs energy data: activities from vapor pressure or EMF measurements
  • volumetric data: dilatometry, density measurements.

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 – SrCl2 liquid phase from experimental data. The object is to optimize the 4 parameters A1, A3, B1 and B3 in the Gibbs energy expression:

  GE = ΔH – TSE
where ΔH = X1X2 (A1) + X12X2 (B1)
and SE = X1X2 (A3) + X12X2 (B3)

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.


Fig. 1 - OptiSage Module - Experimental Data Points: Activity Data.

Fig. 2 - OptiSage Module - Heat of mixing data.

Fig. 3 - OptiSage - Data related to phase equilibria.

Fig. 4 - OptiSage - Experimental Data.

Fig. 5 - OptiSage - SrCl2 liquidus data.

Fig. 6 - OptiSage Module

Fig. 7 - OptiSage - Add Group #5 with data entered and phases selected.

Fig. 8 - OptiSage - Convergent solution of the 2nd optimization.


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Modified : December 4, 2010