Hi...i am calculating Cell Potential for SOFC but i have a problem to find partial pressure for H2, O2 H2O is there design point for fuel composition,so can i start with it to find molar fraction then partial pressure.
The SOFC cell potential (E) can be calculated using the Nernst equation.
Note that The cell potential may deviate from the theoretical Nernst voltage. Some possible reasons could be the following:
1. The cell is under external electrical load
2. The cell has an internal electronic leak
3. The concentration of reactant
s are different from the assumed
values e.g. due to gas leakage
4. The actual cell temperature is different from the measured
5. The cell has a thermal gradient, i.e. the emf + a thermometric voltage is measured.
Here is a good paper that you read to get better understanding:
From S.H. Jensen et al. (2007). International J. Hydrogen Energy, 32, 3253
Hope this information help answer your question.
Professor Yehia Khalil
Yale University
USA
The SOFC cell potential (E) can be calculated using the Nernst equation.
Note that The cell potential may deviate from the theoretical Nernst voltage. Some possible reasons could be the following:
1. The cell is under external electrical load
2. The cell has an internal electronic leak
3. The concentration of reactant
s are different from the assumed
values e.g. due to gas leakage
4. The actual cell temperature is different from the measured
5. The cell has a thermal gradient, i.e. the emf + a thermometric voltage is measured.
Here is a good paper that you read to get better understanding:
From S.H. Jensen et al. (2007). International J. Hydrogen Energy, 32, 3253
Hope this information help answer your question.
Professor Yehia Khalil
Yale University
USA
Well, start with pure dry H2 at atmospheric pressure. That would give you a molar fraction of H2 of 1. At the cathode feed with air (0.21 of oxygen) and there you go! Remeber that when you start drawing current from your cell, you are converting some H2 in H2O (depending on the current). So the molar fraction of H2 will decrease and that of H2O increse. You are also consuming O2, so also that molar fraction will decrease.
The above replies have provided good information relevant to the question, but I shall just point out that using the phrase "cell potential" can be confusing with "electrode potential", and also deviates from the definition of potential in physics. It should be properly called "cell voltage". Unfortunately, the phrase of "cell potential" has been used in several textbooks, including that of Allen Bard, when deriving in fact the cell voltage from different contributing potentials in the cell.
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