Two-Dimensional simulation of purge processes for dead-ended H2/O2 proton exchange membrane fuel cell

Abstract

ABSTRACT Proton exchange membrane fuel cells (PEMFCs) with the dead-ended anode (DEA) and dead-ended cathode (DEC) can achieve high utilization of hydrogen and oxygen but also cause the accumulation of liquid water in the cell and performance degradation. In this study, a two-dimensional multiphase transient PEMFC model is developed to investigate the purge strategy of the PEMFC with DEA and DEC. This model is well validated with the experimental data. The simulation results show that the voltage increases to a certain extent at the beginning of the dead-ended operation and then decreases gradually. During the purging period, the voltage reaches a peak value and then decreases. Therefore, the optimal purge duration is defined as the purge stops when the voltage reaches the maximum value, and the optimal purge duration decreases with the increase of scavenging velocity and increases with the increase of voltage drop rate, however, the energy efficiency under the optimal purge duration is not the highest. Besides, compared with the purging anode and cathode operation, the peak value of the purging cathode operation decreases gradually. Compared with the counter-flow operation, the co-flow operation leads to earlier purging moment, larger ohmic resistance, and voltage decay rate. The excessive accumulation of liquid water leads to a more poor uniformity of the local current density distribution. The purging cathode and counter-flow operation is the most ideal purge strategy during short-time operation, due to the highest energy efficiency about 52.3%, the second-highest output performance, and the second-longest purge interval about 180.01 s.