Proton exchange membrane fuel cell (PEMFC) is expected to be used as a power source of next-generation automobiles and household cogeneration systems, because of its high power density, fast startability, high efficiency and clean power source. There are many problems for the practical use of the PEMFC. One of the important problems is difficulty to optimization of water and heat management within PEMFC. Proper water management of the PEMFC is important to achieve high power density and durability of components. At the high current density operation, gas transport is blocked by liquid water remaining in a GDL and a gas channel, causing a performance decline with increasing concentration overpotential. Water condition is influenced by temperature in the cell. In particular, at the high current density, temperature gradient strongly affects the water transport. Therefore, it is important to grasp the mechanism of water and heat transport inside the PEMFC. In this study, we investigated the effect of a MPL properties on temperature and liquid water distribution.

In order to visualize the liquid water in the PEMFC, an X-ray CT apparatus was used. The resin impregnated graphite was used as the material of a separator, because its X-ray permeability is close to liquid water. The separetor temperature was controlled by a thermocouple and a cartridge heater inserted in the separator. For the temperature measurement at the CL / GDL interface, an Au - Ni thin film thermocouple with a thickness of about 9 μm was fabricated using MEMS technology.

Differences between with and without MPL in liquid water distribution was observed. The presence of a MPL reduce the amount of liquid water near the CL.