gonzix94
Subscriber

 Hi,

I am currently performing the design of a centrifugal compressor working with supercritical CO2 and I wanted to know if the NISTtoRGP application it was posted before can be used for generating the properties table in that state.

I have tried to get values from 1 MPa to 30 MPa (Pcrit=7.37MPa), but it is a bit strange because while creating the tables this message appears:

TPRHO failed so extrapolating 2D data.

P/Pc=(increasing factor until reaching the critical pressure)

I have seen that this does not happen if I just go beyond the critical point.

Can anybody help with this? How can I create a look-up table that include two-phase and supercritical states?

In addition, when I run a simulation with the rgp file I am attaching and my simulation quickly "converges" after like 4 iterations after clipping a lot of variables and putting a lot of walls in the outflow region to avoid reverse flow!!! A total non-sense... Any guesses what is going on?

My inlet conditions are the following ones, just in case it helps:

P=7.69 MPa

T=305K

m=3.06 kg/s

V=25.67 m/s

N=75000 rpm

Thanks!!