Catalytic Combustion problems
 

hello everybody,

I am trying to simulate the catalytic combustion of propane in a channel. The wall surface of the channel is coated with Platinum.
I have written an UDF to describe the wall surface reaction rate and hooked it up to Fluent. The reaction takes place, but my temperature increases with every iteration above 5000K, which is way too high.
If I increase the heat loss through the outer wall to absurd values (150w/m2-k) the temperature decreases.
What can be the problem of the increasing temperature?
I am using the pressure based solver and transport+reaction species model with wall surface reactions, inlet diffusion, thermal diffusion and heat of surface reactions enabled. The specific heat of the species is calculated via a piecewise-polynomial function, of propane/air mixture via mixing law.

Thanks and regards

ps. This is my first time I deal with Fluent.

Well, I created a new mesh and the problem of the increasing temperature doesn't occur anymore.
But now I have some convergence problems with my setup. There are in the majority of cases fluctuations in the residuals of continuity and I don't think I have convergence because there is no flattening of the monitored variables.
Mass flow rate at the outlet and maximum values of temperature on wall and symmetry are monitored.

What can I do to get convergence and improve my solution?
Any recommendations?

Thanks a lot.
Regards

hi ,

yellow-stuff i am experiencing the same problem with you but i am currently working with methane catalytic combustion on Pt. have you found a solution to your problem? if you do, may you help me. thanks a lot in advance