TEA warning

Discusses use of COCO, the process simulation and modelling software suite from AmsterCHEM, downloadable from http://www.cocosimulator.org

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TEA warning

Postby Tom » 20 August 2014, 08:59

Hi,

I get the follwing warnings, see attached.
How to fix it?
Thanks
Tom
Attachments
DME_ie101583j test.fsd
Simulation
(395.36 KiB) Downloaded 689 times
Dok1.docx
warnings
(54.68 KiB) Downloaded 695 times
Tom
 
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Re: TEA warning

Postby jasper » 20 August 2014, 09:12

You are applying a fugacity model based on activity and Poynting correction:

http://cocosimulator.org/index_help.php ... gacity.htm
http://cocosimulator.org/index_help.php ... /poynt.htm

The Poynting correction integrates from Psat to P, but Psat cannot be determined with any accuracy for compounds for which T > Tc. Instead of PSat, Pc is used for such compounds.

Probably a better solution would be for TEA to put a proper extrapolation on the saturated vapor pressure correlation, but this is not implemented. Just extrapolating whichever correlation is used is not a good idea, probably.

It may very well not be important on your model results, the Poynting correction is usually small.

You could tell TEA to suppress all warnings (in the configuration you can tell it to be silent); you will in that case also not see warnings about other temperature correlations being extrapolated outside of their validity region (and errors introduced here might be significant).

Or you could simply leave the warnings as is. They mean to tell you: please be advised that the accuracy of the results should be checked, because rather than extrapolating the saturated vapor pressure correlation, the model has been extrapolated outside its validity region by presuming the vapor pressure is that of the end of the curve (the critical point).
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