Adsorption Rate for a Chemical Reaction on Catalytic Porous Media

mitra · April 28, 2013, 05:22

Hi,
I'm running a program in Fluent which involves chemical reactions which occur in porous media (catalyst). I have Arrhenius rate expressions for these reaction. let me check something first:

1-Is it correct to define them as wall surface reactions (and not volumetric)?

My main question is about the rate of production (or consumption) of species. As you know in addition of reaction rates, it depends on "adsorption rate". I have this expression also, it's a polynomial that each sentence is exponential functions of temperature and partial pressure. But

2- How can I apply them to fluent? Through which panel?

Thank you in advance
Mitra

A CFD free user · April 29, 2013, 14:29

Hi
You need to use source term of your zone boundary and define your reaction consumption or production directly using a UDF. If you have an Arrhenius reaction, you don't need to use UDF, you can define it easily in reaction panel.

mitra · April 29, 2013, 15:57

Thank you.

Meanwhile literature survive, I found a new set of reaction rates which are more useful for my work. (kmole/kg_cat.h). they are functions of partial pressure of species and temperature. the rate expressions are NOT Arrhenius.
I have a new question now:

I have 4 reactions. when writing a udf (define_sr_rate), how can I apply the rate of production (or consumption) for each species, which is a polynomial function of each reaction rate?

A CFD free user · April 29, 2013, 16:25

You need to use SOURCE macro to define the rate of your species separately and then hook them up to the pertinent UDF in source tab of the B.C.
Hope it helps

kostis217 · May 20, 2014, 09:29

hi guys , i want to use UDF in order to define the catalytic reaction rate of c3h8 which depends on the concentration of propane.can you give any clue ?

April 28, 2013, 05:22	Adsorption Rate for a Chemical Reaction on Catalytic Porous Media	#1
mitra New Member Mitra Karami Join Date: Feb 2010 Posts: 4 Rep Power: 16	Hi, I'm running a program in Fluent which involves chemical reactions which occur in porous media (catalyst). I have Arrhenius rate expressions for these reaction. let me check something first: 1-Is it correct to define them as wall surface reactions (and not volumetric)? My main question is about the rate of production (or consumption) of species. As you know in addition of reaction rates, it depends on "adsorption rate". I have this expression also, it's a polynomial that each sentence is exponential functions of temperature and partial pressure. But 2- How can I apply them to fluent? Through which panel? Thank you in advance Mitra

April 29, 2013, 14:29		#2
A CFD free user Senior Member A-A Azarafza Join Date: Jan 2013 Posts: 226 Rep Power: 14	Hi You need to use source term of your zone boundary and define your reaction consumption or production directly using a UDF. If you have an Arrhenius reaction, you don't need to use UDF, you can define it easily in reaction panel. __________________ Regard yours

April 29, 2013, 15:57	How to execute more than one surface reaction rate through udf?	#3
mitra New Member Mitra Karami Join Date: Feb 2010 Posts: 4 Rep Power: 16	Thank you. Meanwhile literature survive, I found a new set of reaction rates which are more useful for my work. (kmole/kg_cat.h). they are functions of partial pressure of species and temperature. the rate expressions are NOT Arrhenius. I have a new question now: I have 4 reactions. when writing a udf (define_sr_rate), how can I apply the rate of production (or consumption) for each species, which is a polynomial function of each reaction rate?

April 29, 2013, 16:25		#4
A CFD free user Senior Member A-A Azarafza Join Date: Jan 2013 Posts: 226 Rep Power: 14	You need to use SOURCE macro to define the rate of your species separately and then hook them up to the pertinent UDF in source tab of the B.C. Hope it helps __________________ Regard yours

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May 20, 2014, 09:29		#5
kostis217 New Member Kostis Chatzi Join Date: Apr 2014 Location: Greece Posts: 20 Rep Power: 12	hi guys , i want to use UDF in order to define the catalytic reaction rate of c3h8 which depends on the concentration of propane.can you give any clue ?