Learning Forum

[Weiqiang Liu]

Hi all,

I've posted a lot of threads about catalytic combustion of methane in micro-channel and a lot of difficulties have been solved by this forum members. Now I need to model last module which is internal diffusion limitation in porous catalyst layer.

In the cases I modeled before, I just ignored catalyst layer and assumed instantaneous diffusion of gas species. However, diffusion limitation inside porous catalyst layer is important though a lot of literature ignored it. I put the geometry including catalytic layer below:

In literature, the author considered diffusion limitation by modifying species boundary equation on wash-coat-fluid interface as follows:

I put all parameters in this equation as follows:

. My question is:

According to these equations, the author just modified the species equation on interface with an effectiveness factor, does it mean this is still a one-dimensional problem and species and temperature contour still can not be obtained from this model? However, the author also calculated catalytic surface area per wash-coat volume. By doing this, did the author just turn the surface reactions into volume reactions in fluent, which makes this a two-dimensional case?

This confuses me a lot. Can anybody help?

Best regards.

Weiqiang.

[DrAmine]

Are you sure that he resolved the porous media?

[Weiqiang Liu]

my opinion is he did not resolve porous media. But I am not very sure. On one hand, seems like he just calculated a lumped effectiveness factor to consider internal diffusion. On the other hand, he used catalytic surface per wash-coat volume, I wonder did he turn the surface reactions into volume reactions.

Best 

Weiqiang