Stoicheometries Flashcards
Define stoicheometry.
The relative quantity of reactant supplied to that consumed by the reaction.
If the exact amount of reactant needed is supplied, what happens in the cell?
The partial pressures of the reactants decrease along the flow channel.
What is the effect of decreasing partial pressure of reactant along a flow channel?
Uneven current distribution, leading to thermal and humidity gradient, and thus low performance.
How can uneven current distributions be improved?
Supplying more reactant than is needed.
What is the effect of low cathode stoichiometry?
Less water removed from membrane.
Lower pressure drop.
Lower pumping losses.
Less contaminant risk.
What is the effect of high cathode stoichiometry?
More even oxygen pressure distribution.
Better liquid water removal.
Higher exhaust heat rejection.
What is the effect of low anode stoichiometry?
Less fuel wastage.
Humidity preserved.
What is the effect of high anode stoichiometry?
Better impurity removal.
Better liquid water removal.
More waste fuel.
