inaccurate redlich-kwong properties for transcritical CO2

kuhbuh · October 20, 2009, 12:32

Hi everyone!

I'm using CO2 for my simulation and the inlet is at transcritical state (10MPa, 35C). I've used redlich kwong equation of state and increased the range of the table generation and max points. However when I checked the results for density (well converged solution) at inlet, it was about 20% lower than compared to REFPROP (@10MPa,35C). Do you have any suggestion please? Thanks a lot!

- kuhbuh

stumpy · October 27, 2009, 17:06

No easy solution. RK is likely not valid in that range. I think you'll need to create an RGP table (see doc). I see that CFX 11.0 has a low and high pressure rgp table available for carbon dioxide (.../ANSYS Inc/v110/CFX/etc/materials-extra), but for some reason I don't see those in 12.0. Check the valid range on those built in tables too.

kuhbuh · October 28, 2009, 00:34

Thanks stumpy! Now I'm creating RGP tables for the range of my problem. The available rgp table for CO2, though for "high pressure", is still below my range. Thanks again!

October 20, 2009, 12:32	inaccurate redlich-kwong properties for transcritical CO2	#1
kuhbuh New Member Join Date: Jun 2009 Posts: 20 Rep Power: 17	Hi everyone! I'm using CO2 for my simulation and the inlet is at transcritical state (10MPa, 35C). I've used redlich kwong equation of state and increased the range of the table generation and max points. However when I checked the results for density (well converged solution) at inlet, it was about 20% lower than compared to REFPROP (@10MPa,35C). Do you have any suggestion please? Thanks a lot! - kuhbuh

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October 27, 2009, 17:06		#2
stumpy Senior Member Join Date: Apr 2009 Posts: 531 Rep Power: 21	No easy solution. RK is likely not valid in that range. I think you'll need to create an RGP table (see doc). I see that CFX 11.0 has a low and high pressure rgp table available for carbon dioxide (.../ANSYS Inc/v110/CFX/etc/materials-extra), but for some reason I don't see those in 12.0. Check the valid range on those built in tables too.

October 28, 2009, 00:34		#3
kuhbuh New Member Join Date: Jun 2009 Posts: 20 Rep Power: 17	Thanks stumpy! Now I'm creating RGP tables for the range of my problem. The available rgp table for CO2, though for "high pressure", is still below my range. Thanks again!