Numerical analysis of air-cooled proton exchange membrane fuel cells with various cathode flow channels

摘要

Air-cooled proton exchange membrane (PEM) fuel cells simplify fuel cell design by combining oxygen supply and air cooling in open cathode channels. Their performance is sensitive to the structure of cathode channels, which significantly affects distribution of temperature, relative humidity and mass transfer in the cells. This study offers a three-dimensional air-cooled fuel cell model with consideration of electrochemistry simulation to investigate the effect of cathode channel design. Experiments are conducted to validate the model. It is observed that obvious gradient in the distributions of temperature, humidity and oxygen concentration lies in the membrane exchange assembly (MEA) between the channel and rib owing to air dual functions in distributing oxygen and cooling the stack. For models with fixed rib-channel ratio of 1.0, the performance is better when channel width is smaller. Considering the effect of contact resistance when the ratio is small, rib-channel ratio within a reasonable range of around 3.0 is preferred in order to enhance the performance. Channels with curved features improve the mass transfer from channel to catalyst layer, thus increasing the cell performance. This study is helpful for enhancing our understanding of the relationship between cell performance and cathode channel design in the air-cooled fuel cell.