Analysis of water behavior in PEFC through 3D thermal and temperature distribution measurement by ultrafine thermocouples

Abstract

Local water behaviors in a PEFC was analyzed by equivalent electric circuit and the temperature distribution with an ultra-fine thermocouples. The thermocouple is tailor-made: thermocouple elements in 50 μm diameter are welded, and electrically insulated with polyimide coating, resulting in the ultra-fine thermocouple. The temperature distribution, which was measured by the thermocouple placed in array configuration, reveals that the cathode catalyst layer shows the highest temperature in the through-plane direction due to the activation over-potential in cathode. Under low humidification condition, however, the anode catalyst layer has the highest temperature triggered by dried polymer electrolyte membrane and increased IR loss. Along gas flow direction, upstream has the highest temperature, because water droplets accumulate in downstream resulting that load current and heat production concentrates in the upstream. In comparison of the temperature in the adjacent channels direction, the tendency of liquid water accumulation under rib makes the temperature under the channel higher.