Electrolyte & Activity Models

Electrolyte solutions can be described in two ways in TP-Cloud. An electrolyte equation of state describes both the vapor and the liquid phase, while an activity coefficient model describes only the liquid phase but brings decades of tried and tested parameters with it.

Electrolyte EoS

Electrolyte equations of state use another type of EoS as basis, such as CPA or SAFT, and add terms to represent the electrostatic interactions of ions¹. The advantage of this type of EoS is that it offers a simultaneous description of both the vapor and the liquid phase.

The following electrolyte EoS will be available in TP-Cloud:

Electrolyte-CPA (e-CPA)

Here, we will provide a more in-depth description of electrolyte-CPA (e-CPA).

Electrolyte-PC SAFT (e-PC SAFT)

Here, we will provide a more in-depth description of electrolyte-PC SAFT (e-PC SAFT).

Electrolyte-SAFT VR Mie (e-SAFT VR Mie)

Here, we will provide a more in-depth description of electrolyte-SAFT VR Mie (e-SAFT VR Mie).

Activity coefficient models

Activity coefficient models are frequently used, with great success, to describe the thermodynamic properties of electrolytes in a liquid phase¹. An advantage with this type of model is that they have been used for a long time, such that tried and tested parameters are available for many components and mixtures. They describe only the liquid phase, in contrast to the electrolyte EoS above.

The following activity coefficient models will be available in TP-Cloud:

e-NRTL

Here, we will provide a more in-depth description of the activity coefficient model e-NRTL.

Extended UNIQUAC

Here, we will provide a more in-depth description of the activity coefficient model called extended UNIQUAC.

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References

Footnotes

1. Kontogeorgis, Georgios M., et al. "A review of electrolyte equations of state with emphasis on those based on cubic and cubic-plus-association (CPA) models." International Journal of Thermophysics 43.4 (2022): 54. ↩ ↩²