感水試験紙を用いた低加湿運転PEFCのアノード側水分状態の可視化計測

抄録

During low humidity operation of polymer electrolyte fuel cells (PEFCs), water management is a critical issue to enhancement of cell performance because low proton conductivity of electrolyte membrane is caused by membrane dehydration. In an operating PEFC at high current densities, water migrates significantly through the membrane from the anode to cathode owing to electro-osmotic drag, and the membrane dehydration occurs mainly at the anode. In order to alleviate this problem known as “dryout”, it is essential to understand the fundamental phenomena of the water transport within the fuel cell. In this study, the water distribution in the anode flow field of a PEFC with low humidity conditions was experimentally visualized by using water sensitive paper (WSP). Furthermore, the dew-point temperature at the anode outlet and the membrane resistance were simultaneously measured, and the effects of inlet gas humidification and current density on the water transport in the anode and the cell performance were discussed. It was found that the water vapor concentration in the anode increases gradually after the startup because of the back diffusion of the product water. Especially at high current densities, the humidification of the anode inlet gas is effective to achieve the proper water management on the anode side and decrease the membrane resistance.