Evaluation of water distribution in a small operating fuel cell using neutron color image intensifier

Neutron radiography is one of the useful tools for visualizing water behavior in operating fuel cells. In order to observe the detailed information about the water distribution in membrane electrode assembly (MEA) and gas diffusion layer (GDL) in fuel cells, a high performance neutron imaging system is required. A neutron color image intensifier (NCII) is a high spatial resolution and high sensitivity neutron image detector. We have developed an imaging system using an NCII for visualizing the behavior of water in fuel cells. The pixel size of the imaging system is around 4.7 μm in the small view field. By using this system, water distribution of a small sized fuel cell was observed continuously every 20 s at the Thermal Neutron Radiography Facility (TNRF). In the results, the water area appears from the GDL and MEA regions, and expanded to the cathode side channel with time. However, the voltage was gradually reduced with time, and steeply dropped. It is considered that the reduction and the drop of voltage were caused by a blockage of gas flow due to accumulation of water in the GDL and the gas flow channel in the cathode side.