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How to define two surface reactions having same flux or reaction rate?

Posted 12 mai 2011, 11:10 UTC−4 Chemical Reaction Engineering, Geometry, Parameters, Variables, & Functions Version 4.1 2 Replies

Jiewen Xiong
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Hi Everyone,

I am using Comsol 4.1 doing a simple simulation on a 1D geometry. There two simple reactions are happening on both end of the line. On the left, the reaction is A to B. On the right, the reaction is B to A. The reaction rate constant is different though. Whenever reaction A to B happens on the left, the reaction B to A will happen on the right. I just simply using the Transport in Diluted species to have the reaction happen. However, I do not know how to make the connection between these two reactions.

This has bothered me for a few day. I am new to Comsol. Anyone can help me out with this?
Really appreciate.

Thank you in advance,

Jay

2 Replies Last Post 15 mai 2012, 22:51 UTC−4
COMSOL Moderator

Hello Jiewen Xiong

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Azadeh Barjasteh
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Posted: 1 decade ago 14 mai 2012, 02:54 UTC−4
Hi Jiewen,
I think you must input two surface reactions by clicking on the Heavy species/Surface reaction and for the left boundary by click on the left boundary in the graphic, select this boundary and input its rate and do this for right boundary.
I think comsol can connect this reactions.
Best ,
Azadeh
Hi Jiewen, I think you must input two surface reactions by clicking on the Heavy species/Surface reaction and for the left boundary by click on the left boundary in the graphic, select this boundary and input its rate and do this for right boundary. I think comsol can connect this reactions. Best , Azadeh
Mohsen Ariana
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Posted: 1 decade ago 15 mai 2012, 22:51 UTC−4
Hi,

If I got you well, you have two reaction in the opposite boundaries of your system and there is a transport of species in the media, probably like an electrochemical cell.
There is no difficulty, define two electrode-boundary interface at the boundaries, input the variables of reaction and the stoichiometric coefficients. Then you can enter the flux of ions into the system.
However, before that you need to define the initial concentration of these ions.
These ions will move from one electrode to the other based on migration and diffusion which is dependent on the mobility and diff. coefficients. Then, you will have a profile of concentrations changing by time.
If your problem is that reaction 2 starts after that product of reaction 1 reaches the other side, then it might be more complicated, because I do not know a way to define a condition for the start of a reaction.

Try to look at model library of COMSOL.

I hope that it would be helpful to you.

Regards,

Mohsen
Hi, If I got you well, you have two reaction in the opposite boundaries of your system and there is a transport of species in the media, probably like an electrochemical cell. There is no difficulty, define two electrode-boundary interface at the boundaries, input the variables of reaction and the stoichiometric coefficients. Then you can enter the flux of ions into the system. However, before that you need to define the initial concentration of these ions. These ions will move from one electrode to the other based on migration and diffusion which is dependent on the mobility and diff. coefficients. Then, you will have a profile of concentrations changing by time. If your problem is that reaction 2 starts after that product of reaction 1 reaches the other side, then it might be more complicated, because I do not know a way to define a condition for the start of a reaction. Try to look at model library of COMSOL. I hope that it would be helpful to you. Regards, Mohsen

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