Soot combustion rate of a diesel particulate filter
 

hi all,

I am doing a diesel particulate filter regeneration simulation with fluent. In specific, it involves soot cake combustion which itself is porous media and the combustion of soot which is trapped inside the porous wall of filter.

In the paper, the soot cake is not in contact with catalyst and the soot trapped in porous wall is in contact with catalyst. Therefore, there are two sets of reaction parameters which are called slow oxidation and fast oxidation. In each different reaction path way, there are different pre-exponential factors, activation energy and concentration exponential.

In the paper, there is a description that says 'in the porous wall of the filter, both contribution of slow and fast oxidation were implemented. In the cake, only the slow oxidation was implemented'

I am very confused about this description. According to the description in the paper, the consuming rate of soot in the porous media is the summation of slow rate and fast rate. As far as I am concerned, the soot consuming rate in porous media is merely fast oxidation rate. Why would it be the summation of fast oxidation and slow oxidation.

I know the description of this thread might be a little abstract. I hope somebody who's doing the similar project can give me some help.

thanks

weiqiang