Thermodynamic Databases

Thermodynamic databases allow us to define and model a chemically reactive system by providing the means for the computation of necessary thermodynamic properties (e.g., standard Gibbs energies of species, equilibrium constants of reactions). In such databases, we find a collection of chemical species and/or reactions and their accompanying data, which include substance’s name and chemical formula, reaction equations, thermodynamic data and/or model parameters.

Attention

There are many thermodynamic databases available in the literature and they are in general very different from each other. At the moment, there is no standard on how thermodynamic databases should be formatted. Some databases are based on chemical reactions and their equilibrium constants (e.g., PHREEQC databases), while others are based on substances and their model parameters for evaluation of their standard thermodynamic properties at temperature and pressure of interest (e.g., SUPCRT92 databases).

Reaktoro currently supports the following thermodynamic databases:

  • SUPCRT92 databases;
  • PHREEQC databases; and
  • GEMS databases.

SUPCRT92 Databases

The SUPCRT92 thermodynamic databases supported in Reaktoro are presented next. They contain parameters for the calculation of standard thermodynamic properties of aqueous species, gases, and minerals for temperatures 0-1000 °C and pressures 1-5000 bar. The standard properties of aqueous species are calculated using the revised Helgeson-Kirkham-Flowers (HKF) equations of state and, for the gases and minerals, a thermodynamic model based on Maier–Kelly heat capacity polynomial equation.

Note

The thermodynamic databases supcrt98.xml and supcrt07.xml, in XML format, were derived, respectively, from the original SUPCRT92 database files slop98.dat and slop07.dat. In the process, all organic aqueous species were removed! If you need them in your modeling problem, you should then use instead supcrt98-organics.xml and supcrt07-organics.xml.

Tip

If your problem requires an aqueous phase without organic species and you are using an automatic initialization scheme for its construction (e.g., creating an aqueous phase with all species in the database whose elements are H, O, C, or Ca), then make sure you are using one of the SUPCRT92 databases without organic species! Otherwise, you might end up with an aqueous phase containing an extremely long list of organic species that will only serve to decrease the performance of the calculations.

Note

The equation of state of Wagner and Pruss (2002) is used to calculate the thermodynamic properties of water and its temperature and pressure derivatives.

PHREEQC Databases

Reaktoro can use PHREEQC as a thermodynamic backend, which permits us to take advantage of the rich collection of PHREEQC thermodynamic databases that are listed next.

GEMS Databases

Reaktoro can also use GEMS as a thermodynamic backend and take advantage of its databases.

Todo

Write about GEMS databases.