Leila Esfahanizadeh

I am engaged in a project, which involved simulating the discharge and dispersion of supercritical CO2 through the nozzles of a cutting tool. 

The geometry comprises a nozzle with an approximate discharge diameter of 0.2 mm, an inlet boundary with supercritical CO2 at 90 bar and 311K, and an outlet at atmospheric conditions, where CO2 disperses into the air. The importance lies in the downstream conditions upon expansion, with a specific emphasis on solid CO2 volume fraction, CO2 mass fraction, and temperature distribution. Our simulation has thus far achieved convergence for equilibrium phase change modeling of CO2 discharge from the nozzle. We have utilized RGP tables for liquid CO2, vapor CO2, and saturation properties in their homogeneous binary mixtures. Furthermore, we've enabled Beta features in our simulations to account for subcooled liquid properties.

In the next step, for non-equilibrium phase change simulation, I also need to use the expert parameters discussed here. Could you please guide me on how I can manually control the critical radius of sub-cooled CO2 in the nucleation model, and an expert parameter for applying the RK equation of state to account for metastable states in the liquid phase? 

I also appreciate any help regarding the modeling structure in which, I can include Air in addition to the CO2 equilibrium binary mixture in the phase change simulation.

Best regards,