AQSol Overview
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| AQSol Overview | AQSol Database Utility | AQSol Model Configuration | AQSol Direct Calc | AQSol Side Calc | AQSol Reactor | AQSol Evaporator | AQSol Flash Tank | AQSol Reverse Osmosis | AQSol Feeder |
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Latest SysCAD Version: 13 May 2026 - SysCAD Build 139.37082
Related Links: Thermodynamic Calculation Engines, TCE Functionality Overview, TCE Species Mapping, TCE Configuration Options, AQSol Example Projects
Overview
The AQSol program can be used for general phase equilibrium calculations and process simulations for aqueous solutions.
- The AQSol software is developed and maintained by Aqueous Solutions ApS, Søborg, Denmark (refer to www.phasediagram.dk for further information).
- It is assumed that the user has some familiarity with the theory and use of the AQSol program.
- This SysCAD TCE library option (in ScdAQSol.DLL) requires the SysCAD "Energy Balance", "Integration Libraries" (formerly "SMDK Runtime") and "TCE" add-ons.
- AQSol must be installed on the computer for the option to work.
- AQSol001 can be downloaded (from www.phasediagram.dk/products) and used for evaluation purposes with a standard SysCAD license. Distributed AQSol example projects use AQSol001.
- For SysCAD, the 32-bit AQSol DLLs must be selected (for example AQSol00132.dll). SysCAD will not work with 64-bit AQSol DLLs.
- AQSol is used in a flexible way in Unit or Control models at appropriate locations in a plant model. It is not implemented as a Species Properties Model.
AQSol Software
AQSol software, developed by Aqueous Solutions ApS (www.phasediagram.dk), is based on an advanced thermodynamic model for salt solutions. It is used extensively in industries where a good understanding of electrolyte solution chemistry is important, such as lithium, potash, base metals, and many others. Input to the software is temperature, pressure (for VLE enabled software products), and ionic composition. Based on this input, AQSol will calculate the amounts and types of precipitate, if any. The software includes all solid phases that are reported with consensus in the open literature. The stable solid phases are found by Gibbs energy minimization. In addition, the enthalpy and the density of the liquid and solid phases are calculated. The bubble point pressure, pH, mean ionic activity coefficient, water activity, and heat capacity of the liquid phase are also calculated. AQSol software is custom built to meet the specific needs of clients. For more information, please contact Aqueous Solutions ApS at [email protected].
To install AQSol correctly, follow the steps in the setup wizard and do not modify the default folder. It should be c:\Program Files (x86)\AQSolXXX\. This ensures that the AQSol add-on can communicate with SysCAD without errors.
Models
AQSol TCE Option unit models:
- AQSol Model Configuration - Used to define and view various options for the selected AQSol database, including management of mapping of SysCAD species list to species list used in AQSol.
- AQSol Direct Calc - Stand alone unit model to perform side calculations using AQSol for predicting aqueous chemistry equilibrium conditions and properties on a user defined AQSol stream.
- AQSol Side Calc - Stand alone unit model to perform side calculations using AQSol for predicting aqueous chemistry equilibrium conditions and properties on a SysCAD stream in the current project.
- AQSol Reactor - Include this model in a SysCAD stream to use AQSol to calculate predicted outlet conditions. Functionality is similar to SysCAD Reaction Block and FEM where for a given feed reactions occur with optional heat exchange. The model can be configured in a number of ways for different purposes.
- AQSol Evaporator - Include this model in a SysCAD flowsheet to model an evaporator using embedded AQSol calculations.
- AQSol Flash Tank - Include this model in a SysCAD flowsheet to model a flash tank using embedded AQSol calculations.
- AQSol Reverse Osmosis - Include this model in a SysCAD flowsheet to model reverse osmosis using embedded AQSol calculations. AQSol can be used to calculate maximum permeate recovery (to incipient solids formation) and other operating modes.
- AQSol Feeder - Include this model in a SysCAD flowsheet to specify a feed using AQSol species. Available from Build 139.30807.
Species Mapping:
- Ionlist is used to breakdown the species to ions. Please see Species Mapping for more information on this topic.
AQSol evaporation models using AQSol DLLs that do not incorporate VLE calculations are suitable for water evaporation only.
Min Water Frac and BPE
Minimum Water Fraction
For AQSol unit models that perform flashing calculations, results may be constrained by the Minimum Water Content setting defined in the project configuration file. The default value is 0.2. This value may be reduced if required, provided the selected activity model remains valid at the higher solute concentrations.
Estimate BPE from Water Activity
BPE can be estimated from the water activity predicted by a TCE unit operation. The PGM Example - Calculate Boiling Point Elevation Using TCE demonstrates how water activity can be used to calculate the boiling point elevation of water, providing a more accurate approach for evaporation calculations.
AQSol SysCAD Project Workflow
The list below are some recommended steps in creating a new AQSol SysCAD project group.
If user only intend to use AQSol for standalone equilibrium calculations, thus not linking it to existing SysCAD stream or species database, then follow the (A). If user wishes to use AQSol to evaluate SysCAD streams, then follow (B).
Important Notes:
- Older versions of the AQSol software require an AQSol configuration file. These are no longer supported. If this is the case, please contact Aqueous Solutions ApS to obtain an updated DLL version.
(A) Using AQSol as stand-alone thermodynamic calculation engine to perform AQSol equilibrium calculations:
- If using a Build before Build 139.30140, extract the AQSol option DLLs from the binxxx_xxxxx_c_ScdAQSol.zip into the SysCADxxx bin folder.
- Create a Configuration File:
- Select the AQSol models in Step 1 of 2 of Edit Configuration File.
- In Step 2 of 2 of Edit Configuration File, select the the AQSol DLL from the TCE tab.
- Create or open a SysCAD project using the CFG file you have just edited.
- Insert a AQSol Model Configuration.
- Load in the AQSol Model Definition file.
- Inset a AQSol Direct Calc Model. Use the direct calc to perform AQSol equilibrium calculations.
(B) Using AQSol to evaluate SysCAD streams or as part of the SysCAD flowsheet:
- If using a Build before Build 139.30140, extract the AQSol option DLLs from the binxxx_xxxxx_c_ScdAQSol.zip into the SysCADxxx bin folder.
- Create a SysCAD.93.db3 file, the SysCAD database must contain the same number of individual phases as the AQSol model file.
- An AQSol Database Utility is available to assist user with the creation of SysCAD.93.db3 file.
- The database is created using existing SysCAD data, AQSol Model data is not transferred to the SysCAD database.
- Once a SysCAD.93.db3 file has been create, copy this database and the IonList.txt into the AQSol SysCAD project \CfgFiles subfolder.
- Check and edit the SysCAD.93.db3 file inside the CfgFiles subfolder and correct any missing data.
- Create a Configuration File:
- Select the AQSol models in Step 1 of 2 of Edit Configuration File.
- In Step 2 of 2 of edit configuration file, select the required Species from the Species Tab.
- Select the AQSol DLL from the TCE tab.
- Create a SysCAD project.
- Add AQSol Model Configuration,
- Load in the AQSol Model DLL file.
- Complete the AQSol Species to SysCAD Species Mapping.
- Edit SysCAD.93.db3 and configuration file if species are missing.
- Once species mapping is satisfactory, add AQSol unit models to the project where appropriate.