Numerical study on the water distribution in GDL and channels of PEMFC applying microchannel bipolar plate

摘要

Water management is an important factor in the implementation of proton exchange membrane fuel cells (PEMFCs). The ionic conductivity of a membrane is dependent on the properties of membrane and water content. However, excessive water amount causes flooding, which disturbs transport of reactant gases. Many researchers have studied proper water management and methods to prevent flooding. Especially, understanding two-phase flow in porous gas diffusion layer (GDL) is needed to prevent flooding. In this study, the effects of operating conditions on the cell performance and water content were studied by a three-dimensional fuel cell model. In addition, the water removal effect of a microchannel manufactured in the bipolar plate was investigated. The active cell area was 10.2 cm~2 and flow fields in anode and cathode were parallel channels. The operating temperature was 50 o C at atmospheric pressure. Stoichiometries of anode and cathode were 1 and 2, respectively. Water content in GDL increased with an increase in the cell temperature. At high stoichiometry condition, total amount of air decreased due to water removal by excessive air. The humidity of air had significant effect on amount of water. The water removal using the microchannel bipolar plate was more effective than that using the conventional bipolar plate. In addition, the water content in GDL using the microchannel bipolar plate was more evenly distributed.