Openmodelica fluid / composition mixture from multiple sources

Question

I am a beginner in Openmodelica and trying to model a flow system with standard libraries. As shown in the picture below, I would like to simulate a system flow from different sources, each with different fluids (gases).

Example:

• source_fluid_1: N2
• source_fluid_2: Ar
• mixed_fluid: fluid mixture of source_fluid_1 and source_fluid_2
• sink

Example of the flow system

For source_fluid_1 and source_fluid_2 I have set the composition X=1 each. In the volume mixed_fluid I have as X_start {0.5, 0.5}.

According to the error information

Base class Medium not found in scope Fluid_Mixture_Example

and 

Class Medium.ExtraProperty not found in scope FluidPort

it seems that I am doing something wrong with the definition of the medium.

But unfortunately I can't get any further here.

With the same fluid (gas) in both sources the model runs without problems.

In addition, I am not sure if I am doing the settings in the composition correctly.

I have looked at the Trace Substances in Modelica's examples, but they don't seem to cover my case.

I am very grateful if someone could help me.

model Fluid_Mixture_Example
Modelica.Fluid.Sources.Boundary_pT source_fluid_1(redeclare package Medium = Modelica.Media.IdealGases.SingleGases.N2, T = system.T_ambient, X = {1}, nPorts = 1, p = 5e5)
Modelica.Fluid.Sources.Boundary_pT source_fluid_2(redeclare package Medium = Modelica.Media.IdealGases.SingleGases.Ar, T = system.T_ambient, X = {1}, nPorts = 1, p = 10e5)
Modelica.Fluid.Sources.FixedBoundary sink(redeclare package Medium = Medium, nPorts = 1)
Modelica.Fluid.Fittings.SimpleGenericOrifice orifice1(redeclare package Medium = Medium, diameter = 0.0015, zeta = 1)
Modelica.Fluid.Fittings.SimpleGenericOrifice orifice2(redeclare package Medium = Medium, diameter = 0.0015, zeta = 1)
Modelica.Fluid.Vessels.ClosedVolume mixed_fluid(V = 1, X_start = {0.5, 0.5}, massDynamics = Modelica.Fluid.Types.Dynamics.FixedInitial, nPorts = 3, use_portsData = false)
end Fluid_Mixture_Example;

OpenModelica v1.18.1 (64-bit)