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Question: Fuel Cell Thermodynamic Equations

  1. Jan 26, 2009 #1
    I'm an undergrad working on fuel cells for a project and I have been using a book to aid me. There are several equations in the book that were not explained properly so I was hoping someone on this forum could help identify how they were derived.

    The first 2 is related to the pressure within the system of the fuel cell. Hydrogen is pumped in 1 end and air in the other and their partial pressure is found using these formulas:

    [tex]p_{H2}=0.5*\frac{P_{H2}}{exp(1.653*i/T^{1.334})}-P_{H2O}[/tex]

    [tex]p_{O2}=\frac{P_{air}}{exp(4.192*i/T^{1.334})}-P_{H2O}[/tex]

    From what I gather, this appears to be Dalton's Law but I am not sure how did the numbers 1.653, 4.192 and 1.334 pop out from.

    The next one is water diffusivity which the author defined as:
    [tex]D_{\lambda}=10^{-6}exp(2416(\frac{1}{303}-\frac{1}{353}))*2.563-0.33*10+0.0264*10^{2}-0.000671*10^{3}[/tex]

    For this one I am not sure what is the significance of 10 in this equation such that is appears 3 times in the equation without being simplified into a constant.

    I'm studying electrical engineering so when it comes to thermodynamics this is way pass me. I hope someone on this forum will be able to help out.
     
  2. jcsd
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