CO2 and CO2- difference in fluent database
 

Hello,

I'am modeling NH3/H2 fuel mixture combustion via EDM. I am using following reactions in the model:

NH3+0,75O2=0,5N2+1,5H2O

H2+0,5O2=H2O

My combustor has two inlets. One is fuel inlet, second is oxidizer inlet. In my case, my oxidizer consist of 0.19 O2, 0.71 N2 and 0.1 CO2 as molar fraction. On the other hand, i arrange the species sequence in fluent as follows and i type 0.21 O2 and 0.1 CO2 in the boundary conditions tab since N2 is a bulk material:

NH3

H2

O2

H2O

CO2

N2

There is two different carbondioxide in fluent database (CO2 and CO2-). when i define CO2 in the materials, my solution diverges. However, when i define CO2-, my solution converges.

My question is, which carbondioxide should i use for my gaseous combustion case. And what is the difference between two different carbondioxide.

If i should use CO2 (not CO2-), how can i solve the divergence problem.

I also modelled the combustion case for NH3/H2/air with same mesh and same settings, my solution is also converges.

If you provide some feedback about this, i appreciate a lot.

Thanks, with my best regards.