Multi-phase systems
Large multicomponent systems can be modeled using the OLI Software. OLI rigorously simulates multicomponent, multiphase systems that may form an aqueous phase, a vapor phase, a second liquid (non-aqueous or aqueous) phase, and any number of solid phases
Thermodynamic properties
Based on a comprehensive Gibbs energy formulation, OLI provides a rigorous prediction of all essential thermodynamic properties including the enthalpy, entropy, heat capacity, volume, chemical equilibrium constants, and activity coefficients. In particular, OLI predicts the properties that are specific to electrolyte solutions, including pH, osmotic pressure and oxidation-reduction potential. Surface tension and interfacial tension are also computed
Redox chemistry
OLI provides for the option of automatically including redox chemistry based on rigorous thermodynamics. A databank supports calculations involving redox of alloys as well as pure elements.
Solid surface / aqueous sorption phenomena
OLI offers the possibility of modeling solid/aqueous partitioning phenomena including surface complexation, ion exchange, molecular adsorption and selected coprecipitation mechanisms.
Predictive models for principal transport properties
OLI provides rigorous predictive models and supporting databanks for predicting electrical conductivity, viscosity, self-diffusivity, and thermal conductivity over wide ranges of conditions.
Aqueous (AQ) Model
An accurate working model, within its limits
OLI's basic electrolyte thermodynamic model - the AQ model - is based on comprehensive aqueous speciation, a predictive Equation of State (EOS) for standard-state properties (Helgeson-Kirkham-Flowers EOS), an activity coefficient model, and convergence heuristics. Combined with 44 years of research and development, and a full-time staff of seven thermophysical modelers, the OLI AQ model covers 80+ elements of the periodic table.
The model is based upon published experimental data. The model uses data regression wherever possible and estimation and extrapolation where required. This model provides general simulation capability giving accurate prediction for almost any water chemistry mixture over the range:
Temperature: -50 to 300 C
Pressure: 0 to 1500 bar
Ionic strength: 0 to 30 molal
The AQ model is an accurate working model within its limits. If your chemistry has not been addressed in the MSE model as yet, and if your system is water-dominant, then the AQ model is a good choice.
Mixed Solvent Electrolyte (MSE) Model
Removing the concentration limit
Where the AQ model is valid to a concentration limit of 30 molal ionic strength, The MSE model predicts electrolyte behavior from infinite dilution to the molten salt limit. The MSE model utilized all prior work on the Helgeson EOS and supporting databank through a conversion of the standard-state chemical potentials provided for aqueous systems. This means that the equilibrium constants and other standard state partial molal thermodynamic properties are readily predicted for mixed solvent environments. The activity coefficient model is new and is based upon an extended Debye-Huckel term, a short-range interaction term, and an ion-interaction term.
Temperature: -50 to 90% of Tcrit of mixture
Pressure: 0 to 1500 bar
Ionic strength: no limit
All current and planned work on transport properties will be done in the MSE model. All extensions to the OLI databank is being done in the MSE model.
The MSE model is OLI's emerging model and it will be the model of OLI's future. This is our only recommended model when you are working with electrolytes that are highly miscible in water and that will form a second solvent. If your chemistry is not completely addressed in this model, OLI thermophysical modeling service can help.
OLI's goal is to provide accurate and reliable electrolyte simulations. We do this through quality data regressions and fits over the range of interest for our clients' applications. Actual data exists for many chemical systems of common industrial interest and, in most cases, we have utilized this data in building our databanks.
Where data is limited or nonexistent, we rely on estimation techniques.
However, for high concentration multicomponent systems, particularly at high temperatures where estimation has been used, the predictions can reflect significant error.
When you have questions about the accuracy of simulations for your system, please send us your chemistry model and conditions of interest. We will evaluate the level of uncertainty that you can expect for your system.
Characteristics
OLI Thermodynamic Models
Rigorous. Extensive. Predictive.
Transport and interfacial properties
OLI has developed frameworks to calculate transport and interfacial properties up to high concentrations. The complete list of what exists in each OLI framework includes:
MSE
Electrical conductivity
Viscosity
Self-diffusivity
Thermal conductivity
Surface tension
Interfacial tension (for two liquid phases)
AQ
Electrical conductivity
Viscosity
Self-diffusivity
OLI maintains a roster of selected, technical papers that describe our capabilities transport and interfacial properties. Please register at Resources (located under Support menu) for the link.