Current - Voltage Variation and Voltage Stability at Constant Load for a PEMFC System with Different Bipolar Plate Flow Fields

Bipolar plates, as one of the main components of a Proton Exchange Membrane Fuel Cell (PEMFC) system, offer a path for a uniform distribution of reactant gases via flow channels, dissipate heat from reaction sites, prevent leakage of gases and offer the electrical connection between multiple cells in a stack. In this study, a BEKKTECH BT-552 PEMFC test station was used in order to investigate the effect of a three different serpentine-type gas flow fields(M1, M2 and M3) with channel width/channel rib ratios a/w of 1, 1.05 and 1.2 on fuel cell performance at two different system backpressures of 70 kPa and 30 kPa. Cell voltage variations of only 16 mV along a current density step of 0.1 A/cm(2)(at high current densities) have been registered for the fuel unit cell containing flow field M3 with a/w = 1.05 at a backpressure of 70 kPa. The same model presented the highest voltage stability under the test at a constant current load of 0.5 A/cm(2) and at a stoichiometric air ratio of 3.2.