.BrineProp.Brine3salts3gas

Information

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.

Usage

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 = h_Driesner+sum(H_{i^app_·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.

Density

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
Germany
francke@gfz-potsdam.de

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, returns gas concentration in kg/kg H2O
density_liq_pTX
density_gas_pTX
specificEnthalpy_liq_pTX
specificEnthalpy_gas_pTX
dynamicViscosity_liq
dynamicViscosity_gas
saturationPressures
thermalConductivity	Thermal conductivity of water
surfaceTension
specificHeatCapacityCp_liq
specificHeatCapacityCp_gas	calculation of gas specific heat capacity