[Olmo95]

Hello everyone,

I am trying to simulate a Heat Exchanger using real gas mixture of supercritical CO2 with other species (COS, NH3, H2S, SO2). I am using the NIST Real Gas Model, which worked well with the pure s-CO2 simulation. But I have several errors when launching the mixtures. I was able to run the mixture s-CO2/H2S and it converged, but for the rest of the mixtures there are errors that do not allow me to run the simulation. I am not sure if the problem is that I am not using the NIST model properly or that the mixtures I want to run are difficult with this model. I am trying converge the solution using first-order discretization as adviced by the Fluent Manual.

Boundary conditions:
- Hot inlet: Velocity 4.702 m/s
- Cold inlet: Velocity 0.843 m/s
- Hot outlet: Pressure 90 bar
- Cold outlet: Pressure 225 bar

I have attached some images of the setup for the NIST model and also some of the errors I am facing. I also attached an image of the geometry I am using.

I hope someone can help me with this problem. Thank you in advance.NIST setup1.PNG

NIST setup2.PNG

error_COS.PNG

error_NH3.PNG

Fluid_vol.PNG