question on the dp_C3P file when JANAF is used

[sylvain_serra]

Hello everyone,
I use CS 2.0.4.

I have a question on the dp_C3P file for gas combustion.
In my case, there is H2 and air that gives H2O and N2.
The dp_C3P file given in DATA/THCH is for C3H8 and air that gives H2O CO2 and N2.
I don't understand how to complete the last line of the file.

Here is the given file
----------------------------------
5 Nb especes courantes
10 Nb de points de tabulation ENTH-TEMP
300. TMIN
3000. TMAX
Especes Gazeuses
C3H8 O2 CO2 H2O N2
.35 .35 .35 .35 .35 coeff absorption (ray)
4 Nb especes elementaires / Composition CHON
.012 3 0 1 0 0
.001 8 0 0 2 0
.016 0 2 2 1 0
.014 0 0 0 0 2
3 Nb d'especes globales (ici : / Fuel / Oxydant / Produits)/ composition en especes elementaires
1. 0. 0. 0. 0.
0. 1. 0. 0. 3.76
0. 0. 3. 4. 18.80
1 Nb de reactions mises en jeu pour les especes globales/stoechiometrie en nb de mole especes globales
1 2 -1. -23.80 25.80
-------------------------------------------------

here is my file:

-------------------------------------------------
4 Nb especes courantes
30 Nb de points de tabulation ENTH-TEMP
300. TMIN
3300. TMAX
Especes Gazeuses
H2 O2 H2O N2
.35 .35 .35 .35 coeff absorption (ray)
4 Nb especes elementaires / Composition CHON
.012 0 0 0 0
.001 2 0 2 0
.016 0 2 1 0
.014 0 0 0 2
3 Nb d'especes globales (ici : / Fuel / Oxydant / Produits)/ composition en especes elementaires
1. 0. 0. 0.
0. 1. 0. 3.76
0. 0. 1. 1.88
1 Nb de reactions mises en jeu pour les especes globales/stoechiometrie en nb de mole especes globales
X X X X
------------------------------------------------------------

Thank you very much for your help.

Sylvain

[Yvan Fournier]

Hello,

See p 91 of the user documentation (or search the pdf file for JANAF). If it is not clear enough, I would need to ask to a combustion version specialist.

Best regards,

Yvan

[sylvain_serra]

Thank you Yvan,

I had already read these documentations and I had some diffuculties to understand the two first terms that in fact are linked to the lignes 14 and 15 of the manual (p91)...

But at the end, I found the results and for those who need the solution, it is :

------------------------------
4 Nb especes courantes
30 Nb de points de tabulation ENTH-TEMP
300. TMIN
3300. TMAX
Especes Gazeuses
H2 O2 H2O N2
.35 .35 .35 .35 coeff absorption (ray)
4 Nb especes elementaires / Composition CHON
.012 0 0 0 0
.001 2 0 2 0
.016 0 2 1 0
.014 0 0 0 2
3 Nb d'especes globales (ici : / Fuel / Oxydant / Produits)/ composition en especes elementaires
1. 0. 0. 0.
0. 1. 0. 3.76
0. 0. 1. 1.88
1 Nb de reactions mises en jeu pour les especes globales/stoechiometrie en nb de mole especes globales
1 2 -1. -2.38 2.88
-----------------------------------------------------


Sylvain

[Meskine]

Hello Sylvain and all

I'm facing the same problem of understanding this last line code.
How does it work ? (if you have understood it)

I would like to proceed to a simple propane combustion as follow :

1.C3H8 + 5.O2 ---> 3.CO2 + 4.H2O

How do I have to edit the dp_C3P file ?

------------------------------------------------------------------------------------------------
5 Nb especes courantes
10 Nb de points de tabulation ENTH-TEMP
300. TMIN
3000. TMAX
Especes Gazeuses
C3H8 O2 CO2 H2O N2
0. 0. 0. 0. 0. coeff absorption (ray)
4 Nb especes elementaires / Composition CHON
.012 3 0 1 0 0
.001 8 0 0 2 0
.016 0 2 2 1 0
.014 0 0 0 0 2
3 Nb d'especes globales (ici : / Fuel / Oxydant / Produits)/ composition en especes elementaires
1. 0. 0. 0. 0.
0. 5. 0. 0. 0.
0. 0. 3. 4. 0.
1 Nb de reactions mises en jeu pour les especes globales/stoechiometrie en nb de mole especes globales
1 2 -1. -?. 7. (I guess)
------------------------------------------------------------------------------------------------

Fix N2 value to 0 even if it defined above will not cause some trouble ? and if I want to insert new gas species like CH4 how does it work concerning JANAF tabulation compatibilities ?

Thanks for your help

[sylvain_serra]

Hello,
I have always some difficulties with this file, and because of the holidays, I have nobody to confirm my answer but, I think that you have 10.O2 and not 5.O2

1.C3H8 + 10.O2 ---> 3.CO2 + 4.H2O

and that your file should be :
----------------
4 Nb especes courantes
10 Nb de points de tabulation ENTH-TEMP
300. TMIN
3000. TMAX
Especes Gazeuses
C3H8 O2 CO2 H2O
0. 0. 0. 0. 0. coeff absorption (ray)
4 Nb especes elementaires / Composition CHON
.012 3 0 1 0
.001 8 0 0 2
.016 0 2 2 1
.014 0 0 0 0
3 Nb d'especes globales (ici : / Fuel / Oxydant / Produits)/ composition en especes elementaires
1. 0. 0. 0.
0. 10. 0. 0.
0. 0. 3. 4.
1 Nb de reactions mises en jeu pour les especes globales/stoechiometrie en nb de mole especes globales
1 2 -1. -10. 7.
-------------------

It is more simple when you have O2 and not air.

good luck

Sylvain

[Meskine]

Thank you for your help Sylvain. I go on my research and if I find something I will post it here.

[sylvain_serra]

Hello,
here we can find a detail exemple for the last line.

http://www.code-saturne.org/forum/viewt ... &t=50#p197

I think that my answers are good.

Sylvain

[Bertrand Sapa]

Hello Sylvain,

If I'm correct, you need 5 O2 to equilibrate your equation, so:

1.C3H8 + 5.O2 ---> 3.CO2 + 4.H2O

Finally, your thermochemistry file should be:

----------------
4 Nb especes courantes
10 Nb de points de tabulation ENTH-TEMP
300. TMIN
3000. TMAX
Especes Gazeuses
C3H8 O2 CO2 H2O
0. 0. 0. 0. 0. coeff absorption (ray)
4 Nb especes elementaires / Composition CHON
.012 3 0 1 0
.001 8 0 0 2
.016 0 2 2 1
.014 0 0 0 0
3 Nb d'especes globales (ici : / Fuel / Oxydant / Produits)/ composition en especes elementaires
1. 0. 0. 0.
0. 5. 0. 0.
0. 0. 3. 4.
1 Nb de reactions mises en jeu pour les especes globales/stoechiometrie en nb de mole especes globales
1 2 -1. -5. 7.
-------------------

Meskine,

If you want to use a different combustible, the code checks if it is present in its JANAF table. If not, you can update the JANAF table or use your own enthalpy-temperature tabulation (dp_C3PSJ).

If you want to use a fuel mixture, you have to create a equivalent fuel and use your own enthalpy-temperature tabulation.

Best regards,
Bertrand

[sylvain_serra]

Hello Bertrand,

your are of course right, I am afraid by my first answer...

Thank you very much

Sylvain