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Sum of NO2, N2O and NO bigger than NOx- values

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Old   May 30, 2018, 04:11
Question Sum of NO2, N2O and NO bigger than NOx- values
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Vladislav Klass
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Hi everybody,


How is it possible that the sum of NO2, N2O and NO values in species_mass.out is sometimes bigger than the NOx values in emissions.out, since NOx should contain these 3 species?


Is there a different calculation model? Or could anybody explain how these values are calculated? I did not find any information on that in the CONVERGE manual.


Here is a link to the trouble making files: https://we.tl/L6oANGgpyi

Cheers!

Last edited by vladislavklass; May 30, 2018 at 04:14. Reason: Link added
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Old   May 30, 2018, 11:41
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Shengbai Xie
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Hi,

It is a very good question. Actually, those two NOx are obtained from different models. The one in emissions.out is from the soot model, the Hiroyasu model most probably. It only works well for high-temperature situations and only three reactions are involved. Whereas the other one (NO2+N2O+NO) in species_mass.out is from the detailed combustion model (SAGE) where more reactions and conditions are considered, as long as the mechanism you used is proper. In a nutshell, they are not necessarily equal and you'd better look at the one in species_mass.out if you are confident about your mechanism.

I hope I have answered your question. Thanks!

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Originally Posted by vladislavklass View Post
Hi everybody,


How is it possible that the sum of NO2, N2O and NO values in species_mass.out is sometimes bigger than the NOx values in emissions.out, since NOx should contain these 3 species?


Is there a different calculation model? Or could anybody explain how these values are calculated? I did not find any information on that in the CONVERGE manual.


Here is a link to the trouble making files: https://we.tl/L6oANGgpyi

Cheers!
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Old   June 7, 2018, 04:59
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Vladislav Klass
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This really helped me, thank you very much!
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Old   June 7, 2018, 14:14
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Shengbai Xie
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Sorry, I meant Zeldovich NOX model, not Hiroyasu soot model.

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Originally Posted by xieshengbai View Post
Hi,

It is a very good question. Actually, those two NOx are obtained from different models. The one in emissions.out is from the soot model, the Hiroyasu model most probably. It only works well for high-temperature situations and only three reactions are involved. Whereas the other one (NO2+N2O+NO) in species_mass.out is from the detailed combustion model (SAGE) where more reactions and conditions are considered, as long as the mechanism you used is proper. In a nutshell, they are not necessarily equal and you'd better look at the one in species_mass.out if you are confident about your mechanism.

I hope I have answered your question. Thanks!
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