Electrochemical reaction in porous zone

davide91 · July 8, 2022, 10:29

Hi all,

Here's a brief description of the system I'd like to simulate.
I have a water flow passing through an expanded metal mesh.
An electrochemical reaction evolves on the metal surface, generating hydrogen and hydroxide anions.
Since resolving the detailed flow throught the matal mesh voids would require an extremely fine numerical mesh, I would rather model the domain as a porous zone with a certain porosity, permeability and area-to-volume ratio.

Here's my problem. Although I turn on the species transport equation, I activate the electrochemical reactions option in the dialog box, and I define the stoichiometry and parameters of the desired reaction, I do not get any evolution of the reaction products.
I have tried changing all the involved parameters (e.g., anodic and cathodic transfer coefficients, specific area, exchange current density etc.) of several orders of magnitude each, with no good results whatsoever.

I suspect that I might be missing something in the problem setup.

I also have contacted the Ansys support provided by the research institute where I work, and I have been told that electrochemical reactions can be defined only on surfaces, not volumes.
I find this particularly suspicious, because a porous zone has an intrinsic specific area, which Ansys requires to give as a parameter.
Moreover, the catalyst layer zones in the Fuel Cell and Electrolyzer module must be treated in that way by the software, since they also are porous zones where electrochemical reactions occur.

I would appreciate any help/comments/thoughts about this.

Cheers,
Davide

Dani2dark · May 6, 2024, 16:05

Hi im having the exact same question.im tring to simulate a simple formic acid direct fuel cell and as for the catalysts, i would like to model the reaction considering catalysts are porous medium and reactions actully happen volumetricly inside them, however defining a surface/volume ratio in the reaction tab , cell zone conditions , doesnt seem to work.
Did you find any solution or explaination on this? i would appreciate it.

July 8, 2022, 10:29	Electrochemical reaction in porous zone	#1
davide91 New Member Davide Masiello Join Date: Jul 2022 Location: Switzerland Posts: 2 Rep Power: 0	Hi all, Here's a brief description of the system I'd like to simulate. I have a water flow passing through an expanded metal mesh. An electrochemical reaction evolves on the metal surface, generating hydrogen and hydroxide anions. Since resolving the detailed flow throught the matal mesh voids would require an extremely fine numerical mesh, I would rather model the domain as a porous zone with a certain porosity, permeability and area-to-volume ratio. Here's my problem. Although I turn on the species transport equation, I activate the electrochemical reactions option in the dialog box, and I define the stoichiometry and parameters of the desired reaction, I do not get any evolution of the reaction products. I have tried changing all the involved parameters (e.g., anodic and cathodic transfer coefficients, specific area, exchange current density etc.) of several orders of magnitude each, with no good results whatsoever. I suspect that I might be missing something in the problem setup. I also have contacted the Ansys support provided by the research institute where I work, and I have been told that electrochemical reactions can be defined only on surfaces, not volumes. I find this particularly suspicious, because a porous zone has an intrinsic specific area, which Ansys requires to give as a parameter. Moreover, the catalyst layer zones in the Fuel Cell and Electrolyzer module must be treated in that way by the software, since they also are porous zones where electrochemical reactions occur. I would appreciate any help/comments/thoughts about this. Cheers, Davide ramakant likes this.

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May 6, 2024, 16:05		#2
Dani2dark New Member Danesh Join Date: Mar 2024 Posts: 1 Rep Power: 0	Hi im having the exact same question.im tring to simulate a simple formic acid direct fuel cell and as for the catalysts, i would like to model the reaction considering catalysts are porous medium and reactions actully happen volumetricly inside them, however defining a surface/volume ratio in the reaction tab , cell zone conditions , doesnt seem to work. Did you find any solution or explaination on this? i would appreciate it.