[ortb]

Hello Fluent forum,

I need help with the Solid Oxide Fuel Cell with Unresolved Electrolyte Module. I have a validated SOFC case where the OCV is calculated correctly.

When enabling electrolysis mode, the model runs without errors, at least at a first glance
— H₂ is produced, and H₂O is consumed as expected. However, the OCV appears independent of the inlet species concentrations. For example, both 10 vol% H₂ / 90 vol% H₂O and 50 vol% H₂ / 50 vol% H₂O yield the same OCV of 0.977 V, which seems incorrect.

Besides enabling Electrolysis Mode, are there additional settings I need to adjust when switching to electrolyis? I've already tried modifying:

Anode/cathode inlets
Electrolyte wall and shadow
Boundary conditions

None of these changes improved the result.

It seems many have had a similar problem, but the answer was never properly stated. Any hints or suggestions would be greatly appreciated!

Thank you in advance!

Best regards,
Benni

[ortb]

I found the solution. You can not prescribe the current density = 0 in electrolysis mode, because in the UDF, the voltage calculation is independent from the species calculation (Q=1).


Instead you are supposed to apply a voltage in excess of the OCV only. Then the current calculation is correct.