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Fuel Cell module: Extreme electrochemical reactions and electric currents

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Old   January 30, 2014, 07:27
Default Fuel Cell module: Extreme electrochemical reactions and electric currents
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Patcharawat
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I'm currently working on fuel cell add-on module to investigate the steady-state performance of 3-channel serpentine flow field PEMFCs.

I think I'm having a problem to obtain a converged solution since the "reversed flow on pressure outlet" massage is shown after a few iteration (about 10 and keep occurring) and the current density in the console window also too high for the high voltage. I have already follow the suggestion (section 2.9) in the Manual which suggest to turn off Joule Heating and Reaction Heating in the Fuel Cell and Electrolysis Models dialog box for the first few iterations after initialization.

Any suggestions would be greatly appreciated. Thank you very much.

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Old   January 30, 2014, 13:55
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Hi,
Based on my experience in using PEMFC module, receiving reversed flow in low voltage is something usual. I mean, when you work on low voltage, which actually is equivalent with high current density (if you set current density in boundary conditions), it's quite possible to see reversed flow in console. But, your problem is quite different. I suppose, you have a problem in your mesh or even you may set B.C inappropriately. So, check it out and see what you did wrongly. Regarding serpentine channels, you need to be very careful. You might have had some problem in generating interior faces between GDL and channels. So, check it too.
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Old   February 2, 2014, 03:07
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Thank you for your suggestion
I've found that I have set Specifi ed Flux (Instead of Specified Value) for the Water Saturation in the UDS Boundary Condition of Inlet. But after I've changed and run a calculation again, a trend of residual is become strange (not like a wave in fig.4 of tutorial http://lljk.org/cfd/pemfc.pdf) and Current density is going up to more than 1.4 A/cm^2.
By the way, I've used parallel processing.

Thank you

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Old   February 2, 2014, 16:32
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@Patcharawat
Ok, it's good to hear that you found at least part of the problem. I still insist that you're making something wrong. I've run this tutorial for many times and I didn't see anything weird. The only thing I faced for the first time that I received divergent error was velocity direction in inlets. Actually, in tutorial manual, there was nothing about how to set velocity vector direction. So, I didn't change it to normal B.C, and hence, I repeatedly received divergent error. After that, I never saw anything wrong regard this tutorial. If you think that a case file of this tutorial could be helpful, send me your email and I will send you a case file which definitely works out.
Good luck
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convergence problem, current density, fuel cell, pemfc, reversed flow

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