Learning Forum

[muhammad.sarwar]

Hi,

Can I simulate non-zerogap (traditional) alkaline electrolyzer in fluent which includes electrochemistry and euler-euler physics? I want to include the bubble effect on the butler volmer.

I have gone through the user guide and found that Potential/Electrochemistry model is specifically for zero-gap electrolyzers and they have mixture model.

Regards,

Muhammad Asim

[Shunichi Tanuma]

 

Hello,

As you informed us, the alkaline electrolysis model installed in Fluent is specifically designed for zerogap electrolyzers and uses the Mixture model.

 

While it is possible to use a standard potential model instead of the alkaline electrolysis model, this cannot be used in conjunction with Euler multiphase model.

 

Thanks,

 

 

[muhammad.sarwar]

Hello Shunichi,

Thanks for the answer!

Please let me know is this correct approach?

I am using species and euler euler (multifluid VOF) model. Two phase I have defined. The phase 1 includes H2O, OH-, H2 (dissolved), O2 (dissolved). The phase 2 includes H2 and O2 gas. 

In Species model, I enabled the electrochemical option and defined the alkaline electrolyer reactions for phase 1.

   

Then in multphase model under the phase interaction's mass tab I defined the phase transfer of H2, O2 (dissolved) into H2, O2 (gas) respectively.

At walls, I enabled the electrochemical reactions in the boundary conditions for anode and cathode. The only concern I have is that will fluent automatically calculates volume fraction when the dissolved species turns into gas under the phase transfer.

Regards,

Muhammad Asim Sarwar

[Shunichi Tanuma]

Hi Muhammad,

I tested this using Fluent 2026R1 on a Windows machine, but the potential model and multiphase model cannot be used simultaneously. Are you using a different version?
The settings in the image you sent appear to be a correct approach.

Thanks,
Shunichi

[muhammad.sarwar]

Hi Shunichi,

I am using Fluent 2024R1. The problem I am facing now is about the volume fraction.

I have defined inter-phase mass transfer in multiphase model. Do I need to specify also bubble generation in boundary condition?

Secondly, can you let me know how should I initialize the model? I first solve the equations for flow, potential, and phase-1 species. Once I get converged solution then I enable equations for volume fraction and phase-2 species. Is this correct?

Regards,

Muhammad Asim Sarwar

[Shunichi Tanuma]

Hi Muhammad,

I understand you are using 2024R1. Upon checking, it appears that the potential model and multiphase model can be used together in versions prior to 2024R1, but not in 2024R2 and later.

If no bubbles are flowing in from the inlet, then setting bubbles in the inlet conditions is unnecessary.

The calculation procedure you provided is fine, or you can solve all the equations from the beginning. Personally, I think solving all the equations from the beginning is more common.

Thanks,
Shunichi