Learning Forum

[Shin]

Hello

I would like to incorporate into my Fluent calculations a reaction in which hydrogen radicals are deactivated by two processes: adsorption of hydrogen radicals on a metal and release of the adsorbed hydrogen radicals as molecular hydrogen.

Is this possible?

Also, do I need a special reaction mechanism?

[Rob]

Surface reactions are possible, and they're covered in the User's Guide. The mechanism will need to be provided, and is also covered in the manual(s). 

[Shin]

Hello, Rob

I understand roughly how to set up the surface reaction.

I think we need to set up a summary reaction for the hydrogen surface reaction, but I don't know what kind of reaction will occur.

Could you please investigate the rate constants of the surface reaction?

[Rob]

All I can do is point you at the documentation - the rate constant will be in /s or similar (SI units) to suit the equations. 

[Shin]

I'm sorry, Rob
What I wanted to say is that I would like to know if you know about the surface reaction between hydrogen and other wall surfaces.
Sorry for my poor English.

[Rob]

No worries, my manager regularly complains about my English! I am English..... 

Only that you can set up the chemistry to do the reactions. If you're looking at embrittlement or similar then it's a bit more complex. 

[Shin]

I would like to investigate the effects of surface reactions on near-wall combustion, including whether they exist.

The surface reaction causes deactivation of hydrogen radicals, and this deactivation is thought to affect the combustion and flame quenching distance.

So, I want overall reaction data that hydrogen radical and surface material surface reaction.

For specific materials, we would like to calculate iron, aluminum, and calcium oxide.

[Rob]

OK, so you'd need to add a volume reaction that includes the radical step (so not just 2H2+O2 => 2H2O)  and then a surface reaction to potentially react the radicals with a surface species. 

[Shin]

I have detailed reaction mechanism that includes the radical step.

So we need to combine that reaction mechanism with surface reactions, right?

I am having trouble finding information on its surface reaction.

[Rob]

Yes. You'll have some volume reactions and some surface reactions. The solver set up is fairly similar. 

[Shin]

Sorry, the information I gave you was not accurate.
I have detailed chemical reaction mechanisms for volume reactions, but not for surface reactions.
I am having trouble finding information on the reaction mechanism of surface reactions.

[Rob]

OK, I can't help with that. Have you tried NIST or the like?