Abstract
To alleviate water flooding and membrane dryout in polymer electrolyte fuel cells （PEFCs）, it is necessary to elucidate mass
transports and electrochemical reactions occurring in membrane electrode assemblies （MEAs） by various measurements and
simulations and to design the optimum fuel cell structure for better water management. Our research group has developed several
measurement techniques for investigating the liquid water behavior and quantifying the water vapor concentration within the flow
channel and porous electrode of an operating PEFC based on cross sectional visualization, X-ray radiography and laser absorption
spectroscopy. The details of their measurement methods and utilization examples were explained in this article.
