In-situ visualization of liquid water in an operating PEMFC by soft X-ray radiography

In order to visualize the liquid water in a PEMFC, in-situ soft X-ray radiography technique has developed. Low energy X-ray in soft X-ray range makes it possible to visualize the liquid water in a PEMFC. The temporal and spatial resolution of the technique were improved and the real-time imaging was realized. Through-plane and in-plane visualization tests of an operating PEMFC were carried out. The results of through-plane visualization tests showed a strong separation of the liquid water between the under rib area and the under channel area, and non-uniform distribution of liquid water with the range of several dozens to hundreds of μm was observed. In addition, the liquid water discharge behavior near under the rib area was observed by an in-plane visualization test. These results suggested the importance of a detailed understanding of the liquid water transport processes inside the PEMFC, and the soft X-ray radiography makes this investigation possible.