A novel ribbed cathode polar plate design in piezoelectric proton exchange membrane fuel cells

Abstract

Previous studies have indicated that a novel design for proton exchange membrane fuel cells with a piezoelectric (PZT) device, which is regarded as an actuator for pumping air onto the cathode channel, can offer better performance with higher current generation. These results indicate that piezoelectric proton exchange membrane fuel cells (PZT-PEMFCs) may compress more air into the catalyst layer and thus may enhance electrochemical reactions, resulting in higher current output. At the same time, produced water vapor is pumped out from the cathode channel during the compression process. Previous studies on PZT-PEMFCs without ribs showed the strong effect of ohmic and concentration losses. In this study, a shallow rib is chosen to reduce the aforementioned losses and pressure drop in the cathode channel. The rib design is an important parameter that can be used as the support for the membrane electrode assembly (MEA). A transient three-dimensional model is built to simulate and compare the performance of PZT-PEMFCs both with and without ribs. Water vapor, oxygen, and current density profiles in the PZT-PEMFC are studied in detail. The major operating parameters include the rib width and the PZT vibration frequency. Our results show that the ribbed cathode channel can reduce ohmic losses and double current generation. Moreover, at higher PZT vibration frequency ( f = 64 Hz), an air-breathing PZT-PEMFC compresses more oxygen into the catalyst layer and thus enhances the electrochemical reaction, resulting in a higher current output (0.208 A cm −2).