BrineProp.Brine3salts3gas is a medium package that, based on Brine.BrineProp.PartialBrineMultiSaltMultiGasTwoPhase, defines a brine property model with 3 salts (NaCl, KCl, CaCl2) and 3 gases (CO2, N2, CH4), which are the main constituents of the geofluid in Gross Schoenebeck, Germany.

It was used for the calculations documented in this PhD thesis.


As it is based on Modelica.Media, the usage differs little from the usage of the two-phase water model:

Create an Instance of the Medium (optionally deactivating range checks, for all options see .PartialFlags ):

 package Medium = Brine_Duan_Multi_TwoPhase_ngas_3;

Create an Instance of Medium.Baseproperties:

Medium.BaseProperties props;

Use the BaseProperties model to define the actual brine composition(Xi or X), to define the thermodynamic state and calculate the corresponding properties.

props.p = 1e5;
props.T = 300;
props.Xi = {0.08, 0.004, 0.12, 1-4, 7e-4, 6e-005} "NaCl, KCl, CaCl2, CO2, N2, CH4"
d = props.d;

See BrineProp.Examples.BrineProps2phase for more usage examples.

All calculated values are returned in SI units and are mass based.

Specific Enthalpy:

The enthalpy is calculated as a mass fraction weighted average of the enthalpies of the two phases.

h = x·h_g + (1-x)·h_l

Specific enthalpy of gas phase:

Enthalpy of the gas phase is modelled as the enthalpy of an ideal mixture of ideal gases, i.e. it is calculated as the mass weighted average of the individual gas enthalpies including water.

h_g = sum(h"i·X"i)

The individual gas enthalpies are calculated using the functions for ideal gases in Modelica.Media.IdealGases.SingleGases.

Specific enthalpy of liquid phase:

Enthalpy of the liquid phase is assembled from the enthalpy of a NaCl-solution (Driesner) and the apparent molar enthalpies of the salts multiplied by their respective molalities

h_l = hDriesner+sum(Hiapp·bi)

The apparent molar enthalpies of KCl and CaCl2 are calculated from apparent molar heat capacities which are calculated from a 2D fit for data from literature. The contributions of MgCl2 and SrCl2 are neglected, due to their small influence in the GrSbk fluid.


The total density d of the fluid is calculated by combining the densities of both phases (d_g and d_l) according to their volume fractions. The gas phase is assumed to be an Density of the gas phase is assumed to be an ideal mixture of ideal gases.

d = 1/(x/d_g + (1 - x)/d_l)

Density of the gas phase:

Gas density is calculated using the ideal gas law.

Density of liquid phase:

Density of the liquid phase is calculated by combining the densities of solutions of single salts. The density model by Duan for single salt solutions is adapted for multi-salt solutions, resulting in an approach with apparent molar volumes analogous to the mixing rule for enthalpy.
Created by
Henning Francke
Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences
Telegrafenberg, D-14473 Potsdam


Name Description
 fugacity_H2O Calculation of fugacity coefficient according to (Duan 2003)
 setState_pTX to avoid check error
 setState_phX to avoid check error
 solubilities_pTX solubility calculation of CO2 in seawater Duan, Sun(2003), returns gas concentration in kg/kg H2O
 thermalConductivity Thermal conductivity of water
 specificHeatCapacityCp_gas calculation of gas specific heat capacity


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