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Old   January 12, 2011, 20:11
Default species transport in FLUENT
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Hi all,

I am trying to simulate coal gasification using species transport, finite rate chemistry/eddy dissipation model....

These are the reactions I want to include:

Heterogeneous Reactions:
C(s)+0.5O2 --> CO
C(s)+CO2 --> 2CO
C(s)+H2O --> CO+H2

Homogeneous Reactions:
Volatiles+O2 --> CO2+H2O
CO+0.5O2 --> CO2
CO+H2O --> CO2+H2
CO2+H2 --> CO2+H2O
H2+0.5O2 --> H2O

I have created coal-volatiles-air as the mixture material...but having confusion over what species to include in the mixture /fluid /solid under the materials tab...I am using FLUENT 12.1 version...

could anyone suggest on this...plz help....

thanks
Arnab
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Old   January 15, 2011, 12:28
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How You introduce fuel into domain? Are You using DPM model for injecting coal particles?
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Old   January 15, 2011, 12:33
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yes..I am using DPM for coal injection..(group/surface)..when I include the Volumetric and particle surface reactions..I can input the proximate and ultimate analysis, HHV values using the coal calculator in species transport..

thanks..
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Old   January 15, 2011, 14:57
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Yes, I have the similar problem, and unfortunatley I didn't found solution yet. I model biomass pelet combustion with same models, as You used (SPECIES TRANSPORT, DPM, Injection fuel particle). My problem is to find out how to "control" (I mean to fast up and slow down) reactions in gas phase and heterogenous reactions. I try to change preexponetial factor and activation energy for these reactions but nothing yet, I don't have logical solutions. For example I want to slow down burning CO to CO2, because I get very small amount of CO in my outflow. Of course temeparture and turbulency also influnced on these. I try to change them also, but nothing significantly happened.
I'll keep trying and I'll inform You, if I make any progress.
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Old   January 21, 2011, 13:24
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You have enabled multiple char reactions?

In fluid/solid you should include C(s) (it is in fluent library)

Best Regards,
Nikolopoulos Aristeidis
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Old   January 21, 2011, 17:44
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Quote:
Originally Posted by Nikolopoulos View Post
You have enabled multiple char reactions?

In fluid/solid you should include C(s) (it is in fluent library)

Best Regards,
Nikolopoulos Aristeidis
Thanks for joining in topic!

OK! I include C(s) (which represent char) in my model, but how can I enable "multiple char reactions". Does it particle surface reactions?

Everyone mention UDF for heterogeneous reactions. Does it necessery? I'm not so good in writing UDFs.
Can I bypass it in this model?
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Old   January 22, 2011, 09:14
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Quote:
Originally Posted by nmanic View Post
Thanks for joining in topic!

OK! I include C(s) (which represent char) in my model, but how can I enable "multiple char reactions". Does it particle surface reactions?

Everyone mention UDF for heterogeneous reactions. Does it necessery? I'm not so good in writing UDFs.
Can I bypass it in this model?
multiple char reactions is selected in the panel of materials in the drop down list for char burnout model.

Yes you can avoid UDF. Fluent creates a panel for heterogeneous reactions for C<s> similar to homogeneous reactions.
However if the rate expression is complicated you will probably need a UDF.

I'm home and i don't have fluent at home. I hope i remember correctly
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