Effect of Anode Stoichiometry and Back Pressure on the Performance of PEMFCs

In this study, the performance of polymer electrolyte membrane fuel cells was investigated. Two important operating conditions, namely the anode stoichiometry ratio and cell's back pressure were considered, whereby their effect on the cell performance was analyzed in isolation and relative to each other. Polarization curves showed that when operating the cell at low back pressure, an increase in the anode stoichiometry resulted in an increase in the cell performance due to enhanced fuel cell thermodynamics. However, upon increasing the back pressure, an increase in the anodic stoichiometry resulted in a poorer performing cell due to an increase in the hydrogen crossover rate and an increase in membrane resistance. From this work it became evident that the relationship between back pressure increment and anodic fuel stoichiometry was not linear, and requires optimization.