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GEM-Standalone: Solution Models

TSolMod C++ Class Library of Mixing Models in Phases-Solutions

Predicting the stability and thermodynamic properties of non-ideal solution phases over wide pressure and temperature ranges requires theoretically sound and sufficiently accurate equations of state and activity models. Within the generalized GEM framework, the diversity of such models calls for a novel, flexible, and computationally efficient code architecture. This need led to the development of the TSolMod C++ class library, ensuring broad applicability of GEM software, particularly in GEM-Selektor v.3 and the standalone GEMS3K code.

Key Features

  • Generic and flexible model parameter setup.
  • Computationally efficient data exchange with the GEM IPM equilibrium solver.
  • Open conceptual design allowing easy integration of new solution phase models.

The current version of TSolMod includes a comprehensive selection of fluid, gas, liquid, and solid solution models applicable to geochemistry, petrology, materials science, and chemical engineering.

Reference: 

Wagner T., Kulik D.A., Hingerl F.F., Dmytrieva S.V. (2012). GEM-Selektor geochemical modeling package: 
TSolMod C++ class library and data interface for multicomponent phase models. 
Canadian Mineralogist 50, 1173-1195 (https://dx.doi.org/10.3749/canmin.50.5.1173).

Implemented Activity and Equation of State Models

Multicomponent Fluids and Gases

Model Name       Description
TSRKcalc Soave-Redlich-Kwong cubic equation of state with Van der Waals mixing rule (constant/T-dependent parameters).
TPR78calc Peng-Robinson cubic equation of state with Van der Waals mixing rule (constant/T-dependent parameters).
TPRSVcalc Peng-Robinson-Stryjek-Vera cubic equation of state with Van der Waals mixing rule (constant/T-dependent parameters).
TCORKcalc Compensated Redlich-Kwong (CORK) hybrid cubic and virial equation of state with Van Laar mixing rule.
TSTPcalc Sterner-Pitzer Helmholtz energy-based equation of state for high-pressure systems with Van Laar mixing rule.
TCGFcalc Perturbation theory-based Churakov-Gottschalk equation of state with basic Van der Waals mixing rule.

Liquid Multicomponent Non-Electrolyte Solutions

Model Name       Description
TWilson Wilson local composition activity model with T-dependent non-randomness parameter.
TNRTL Non-random two-liquid (NRTL) local composition activity model with T-dependent non-randomness parameter.

Multicomponent Solid Solutions

Model Name       Description
TIdeal Ideal mixing model for fluids, gases, and solid solutions, supporting multisite ideal formalism.
TBerman Microscopic-interaction multisite model for solid solutions.
TRegular Regular activity model of mixing (symmetric formalism).
TVanLaar Van Laar activity model (asymmetric formalism).
TRedlichKister Four-term Redlich-Kister activity model.

Ternary and Binary Solid Solutions

Model Name Description
TMargules Ternary regular Margules activity model.
TSubregular Binary subregular Margules activity model.
TGuggenheim Binary 3-term Redlich-Kister activity model.

Multicomponent Aqueous Electrolyte Solutions (Ion-Association Models)

Model Name       Description
TDebyeHueckel Two-term Debye-Hückel equation model.
TLimitingLaw One-term Debye-Hückel limiting law.
THelgeson Extended Debye-Hückel equation with common constant or T-P-dependent extended term parameter, and common ion size.
TKarpov Extended Debye-Hückel equation with individual ion sizes and T-P-dependent parameters.
TShvarov Extended Debye-Hückel equation with common ion size and T-P-dependent parameters.
TDavies Davies equation form of the extended Debye-Hückel model.

Multicomponent Aqueous Electrolyte Solutions (Specific Ion Interaction Models)

Model Name       Description
TSIT Two-term Specific Ion Interaction (SIT) model.
TPitzer Pitzer (Harvie-Moller-Weare) model with T-dependent binary and ternary interaction parameters.
TEUNIQUAC Extended UNIQUAC (Thomsen) model with T-dependent binary interaction parameters.

(The library is continuously evolving and expanding.)

For a detailed description of calculations performed in most TSolMod library models, refer to the Activity-Coeffs.pdf file from the GEM-Selektor documentation.