Investigation of performance characteristics and water flooding in the cathode flow channel of a polymer electrolyte membrane fuel cell

摘要

This study was experimentally carried out to investigate the relationship between fuel-cell performance and the water flooding phenomena at the cathode, which is an important research area of water management in the polymer electrolyte membrane fuel cell. A transparent fuel cell was fabricated to observe the water flooding phenomenon in the cathode channel. Images of the flooding phenomena were obtained by digital and high-speed cameras under various operating conditions involving cell temperature, cathode flowrate, humidifying temperature, cathode backpressure, and oxygen concentration. At the same time, performance was measured at the potentiostatic mode. In this study, investigations for the effects of operating parameters on the water flooding phenomenon, as well as water droplet generation and removal in the cathode flow channel were made. As time elapsed, it was seen that small water droplets formed and then grew into larger water droplets, when the flooding phenomena occurred. It was also observed that when the cell temperature increased the occurrence of flooding phenomena decreased due to evaporation, and performance was significantly improved. The water droplets in the cathode channel were found to be almost zero at high cathode flowrates, and the instances of the flooding phenomenon were decreased by evaporation as the humidified temperature was increased. On account of increasing cathode backpressure, the flooding phenomenon due to high partial pressure was reduced and as compared to air when oxygen was used as an oxidant, the water distribution was increased. Based on this experimental study, it is seen that the flooding phenomenon is closely related to fuel-cell performance.