Abstract
Dew point diagrams show the dew point temperature of the anode and cathode outlet gas streams as function of the cell pressure, stoichiometric flow ratios and the effective drag coefficient of water across the membrane in a PEM fuel cell. They are a useful tool for specifying the operating temperature for a given pressure and stoichiometric flow ratio to avoid cell flooding or membrane dehydration. In this work a sequence of logical steps is presented that help determining the optimum cell operating conditions in a natural way rather than employing a trial-and-error method. Furthermore, modeling results are presented for the specified case. The results indicate that fuel cell operation on completely dry inlet gases at anode and cathode stoichiometric flow ratios of ξa = 1.03 and ξc = 1.1 is possible. However, the predicted membrane hydration level of λ ≈ 9 for this case is below expectation.