Learning Forum

[mehmood.khizerme]

Hi,

I have a question regardng specifying the reaction boundary condition for SOEC Modeling. I am using the SOFC Unresolved Electrolyte model for the simulation and I have just a quick  queson that n the SOFC panel if i define all the parameters correctly do I still need to specify the type of reaction in the species model panel for the later use in setting up the boundary conditions or SOFC model can do it itself, i am confused.

When i enable the SOFC model it only checks the volumetric reaction and not the electrochemical one, so in short my questons are

1. Do i have to manually input the cathodic and anodic reactions in species model tab or SOFC model can take care of it?
2. Do i have to enable the electrochemical reaction too because SOFC didnt activate it?

[Aleksey Gerasimov]

 

Hello Mehmood,

The answer to both questions is “No”.

There is no need to provide such inputs in the species panel. The dedicated fuel cell panels take care of the setup. The reason being is that we are not explicitly solving for the ionic species. Their transfer is accounted by other means in the model. Please follow the user guide and tutorial materials for setting up the case.

The only time one needs to go into the Species Model panel, if there is a need to define internal reforming reactions within SOFCs, but for normal hydrogen operation of SOFC or in the simulations of SOEC, this is not needed.

Hope this helps and kind regards,

Aleksey.

 

[mehmood.khizerme]

Thanks Aleksey for your assistance, a lot of concerns have been cleared and i guess i dont have to worry about settng up of reactions.

I have consulted and followed all the steps mentioned in the Ansys Fluent 2024 R2 user guide for the problem setup but still the issue persists as there is no hydrogen production and the user guide has no guidance regarding setting up the boundary conditions.

When i open up the cell zone conditions panel an in its reaction panel there is mechanism-1 specified but when i look into it there are no reactants or products present. Could this be a reason for no reaction at all?

 

Regards

[Aleksey Gerasimov]

Hello Mehmood,

Please leave the reaction mechanism untouched in the "Cell Zone" ->"Reaction" tab. If the reaction is not glowing, then please try to reinitialize the case differently, fun the simulation with the fluid flow, energy and species only, to ensure a realistic distribution of steam. Please ensure that the conditions for the reversed flow are set realistically and the temperature of the cell is sufficient to support the reaction. It is worth paying particular attention to this aspect if you see  reversed flow at the outlets. Once you see that the steam is available in the reaction zone and everything looks realistic, then you can switch on the electrochemistry sources. There are different solution-steering strategies are available and covered by tutorials. 

You can also switch on the solution of the potential equation, as an initial or interim step, and see whether the potential distribution looks realistic or not.

The last issue, please see whether the anode and cathode are specified constently. The convention is different for power-producing devices, such as fuel cells, and for power-consuming equipment, such as electrolyzers. Our dedicated PEMWE and AEM electrolysis models have the correct notation. The SOEC model however, has it similar to SOFC, and not in-line with this convention. The reason being is that the addon fuel-cell module is used for this purpose, with fuel-cell, convention and is forced to work in reverse. The user guide explains this deviation from the convention.

Please check,

Kind regards,

Aleksey.

[mehmood.khizerme]

Thanks Aleksey for your assistance, I have read about inverse notation for the case of electrolysis now what confuses me is that that do I have to input each and every parameter as that for fuel cell and not electrolysis like swapping the voltage and current taps, cathode and anode materials, anode and cathode electrolyte interfaces 

Secondly for the initialization step no matter from where i compute the values from in the standard initialization there is no source listed for electric potential it shows as zero. So do i have to specify the udf source::sofc in the electric potential source in cell zone conditions at the electrode

Lastly in the boundary conditions tab, both the materials for anode and cathode electrolyte interfaces are automatically specified as cathode material for the wall and wall shadows and whn I change one other changes itself. Is it normal?

I have been using the ansys student version and i guess i cannot access the relevant tutorials with it.

Regards 

[mehmood.khizerme]

Hello Aleksey,

I just have this question if you can kindly answer it, my SOEC design has the same porous air/steam flow channel and current collectors means anodic CC and steam flow channel and cathodic CC and air flow channels are specified the same and not as dfferent layers and materials. Now the issue I am facing is that I have followed each and everything as per the ANSYS tutorials on SOFC and user and theory guide, SOFC mixture is default even for the air flow channel when I specify the porous fluid material air the FLUENT gives SIGSEGV error and abruptly shuts down, as per the Ansys User guide (pg. 1345) aren't we supposed to define that specific flid that flows through that porous channel.

Secondly in the tutorial that I am following it says that only those sources should be enabled that flows through that domain lke O2 is disabled for steam flow channel but in my case all species sources like h2o, h2 and o2 sources are enbled as default and there is no source enbled for electric potential.