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Sumon October 14, 2005 23:29

PEMFC and Permeability
Hi All

Actually I am going to work on PEMFC. I have found that the value of permeability (POROSITY FOLDER) in PEMFC module of STAR-CD is not clear! Can anyone tell me that what is the unit of beta (should be permeability co-efficient)? and what is alpha as well? It seems like the value of beta should be inverse of the permeability!?

I couldnot help myself to remove the confusions. Please help me if anyone knows.


Craig Linne November 15, 2005 20:22

Re: PEMFC and Permeability
The Star Method guide (a .pdf file) has some good examples on how they derive alpha and beta. For laminar flows (I believe PEMs are laminar) you have Alpha as zero and only beta. Without the fluid velocity, though, I don't think you can get permeability from Beta only.

Resistance=alpha+beta*velocity, Pressure_drop=Resistance*velocity.

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