Gas phase reactions

[francescalb]

It does not seem that gas phase reactions are implemented in omkm, although an example on such a reactor set up is given in the examples: .

With pmutt I am able to write (cti and xml) files that include reactions that occur in the gas phase as well as on the surface. While it is an alternative to stick to pure cantera without openmkm for sole gas phase systems, this is not so easily achievable when I need both surface reactions and gas phase reactions.

It might very well be that I am doing something wrong, so do you have an example on such usage?

The error is get when running OpenMKM is:

''' Error raised in Cantera. Exiting...

---

CanteraError thrown by GasKinetics::addReaction: Unknown reaction type specified: 20

---

''' A first test was made by simply adding the direct formation of NH3 from N2 and H2 in the gas phase (in your openmkm example from pmutt) in addition to all the surface interactions.

I would be very grateful on some pointers on how to proceed here.

[mbkumar]

Hmm. Both gas phase and surface phase reactions are supported in openmkm. Could you please share your input file? I'd like to check it for its correctness.

Bharat

On Thu, Oct 21, 2021, 4:30 AM francescalb @.***> wrote:

It does not seem that gas phase reactions are implemented in omkm, although an example on such a reactor set up is given in the examples: https://github.com/VlachosGroup/openmkm/blob/master/examples/rctr_input_files/batch_gasonly.yaml .

With pmutt I am able to write (cti and xml) files that include reactions that occur in the gas phase as well as on the surface. While it is an alternative to stick to pure cantera without openmkm for sole gas phase systems, this is not so easily achievable when I need both surface reactions and gas phase reactions.

It might very well be that I am doing something wrong, so do you have an example on such usage?

The error is get when running OpenMKM is:

''' Error raised in Cantera. Exiting...

CanteraError thrown by GasKinetics::addReaction: Unknown reaction type specified: 20

''' A first test was made by simply adding the direct formation of NH3 from N2 and H2 in the gas phase (in your openmkm example from pmutt) in addition to all the surface interactions.

I would be very grateful on some pointers on how to proceed here.

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[francescalb]

Sure,

I have uploaded a thermo.xml file (renamed with .txt as github does not support .xml uploads). It has been generated with the openmkm example in pmutt, only with the change of adding a direct reaction between N2 and H2 to form NH3 in the gas phase (I know, not very likely to occur...), with a completely invented Ea and A. The error message is the same.

thermo.xml.txt

[skasiraj]

@francescalb I just checked by adding a gas phase reaction to the "CTI" file from the (pmutt-openmkm) example, and then used the CTML thermodynamic input file for an OpenMKM run, and it seems to run okay for me. As @mbkumar suggested it would help to check the input file for correctness.

Couple of pointers for the CTI file.

• Make sure you change the reaction keyword in your "CTI" file i.e. change from surface_reaction() to just reaction() for gas phase reactions or choose from a list of reaction types supported by Cantera: reaction types
• If you are using CTML input then just remove the type="surface" tag for the gas phase reactions.
• Also, if you have a gas phase reaction it should be added to the list of reactions for that specific "phase" definition at the top of the file. Every reaction should be uniquely be associated with a given phase (Be it gas/bulk or 2d-interface) ideal_gas(name="gas", elements="N H", species="N2 NH3 H2", reactions=[**enter the gas phase reaction id or ids here**])
• Similar logic also applies to the phase definition in the CTML file via the reactionArray node. ` ...

  ... `

[skasiraj]

Sure,

I have uploaded a thermo.xml file (renamed with .txt as github does not support .xml uploads). It has been generated with the openmkm example in pmutt, only with the change of adding a direct reaction between N2 and H2 to form NH3 in the gas phase (I know, not very likely to occur...), with a completely invented Ea and A. The error message is the same.

thermo.xml.txt

Just remove the type="surface" for the reaction 14. Since this is not a surface reaction.

[francescalb]

Ah, thank you very much! You can then disregard my comment. Indeed you are right, the gas phase reaction was set to be a surface_reaction and in the xml, it worked with setting type="" for that particular reaction.

Thank you for the quick and very helpful reply! (Now going back to find out how to do it correctly with pmutt :) )