Verification of Generated Water in a Super-cooled State Below Freezing Point in PEFC

Abstract

When a fuel cell is operated below freezing point, generated water is frozen inside the fuel cell leading to a drop in performance. This is one of the most important problems that must be solved with regards to PEFC. Until now, however, few papers were published that discuss where the generated water freezes in the fuel cell. This research, therefore, was carried out for the purpose of clarifying the phenomenon of water freezing below freezing point. In order to achieve this, we observed the water generated on the surface of the catalyst layer simultaneously with visible and infrared images. The results revealed surprisingly that water generated below freezing point was in a liquid state at the time of generation and maintained a super-cooled state. It is generally known that a large rise in temperature is experienced when water in a super-cooled state starts to freeze.