Non-ideal compressible fluid dynamics is a novel research field which studies the behavior of dense, supercritical or two-phase fluid flows. Complex models are now being developed to describe the thermodynamic behavior of these fluids in various regimes, often based on empirical results. In the present work, experimental data is used to assess the predictive capabilities of the SU2 flow solver coupled with the Peng-Robinson equation of state together with variable specific heats for the hexamethyldisiloxane in its non-ideal vapor state. The experimental campaign is carried out in the Organic Rankine Cycle Hybrid Integrated Device facility, also called ORCHID, in Delft (NL).