Neutron imaging of water distribution in full size automotive fuel cells
The high penetration of neutrons through large thicknesses of metals (e.g. > 10 cm of aluminum) allows imaging the water distribution in single fuel cells of full size design, even between the thick compression bodies requested to ensure enough flatness over a large area. For the single cell to have thermal boundary conditions similar to those of a cell integrated in a stack, the compression bodies are heated and a specific temperature gradient is applied to mimic the temperature gradient in the cell itself.
Typical setup for neutron imaging of full size cells
- The beam diameter and detector size at the NEUTRA beam line of PSI allows imaging objects up to a size of 400 mm x 400 mm in a single shot.
- Typical exposure times of 5 to 10 seconds allow observing the temporal evolution of water in the flow channels.
- With accumulated exposure time of 2-3 minutes, a low noise image is obtained, which allows identifying the presence of water in the GDLs in regions free of channel water.
- The NRES group has extensive infrastructure and expertise to setup and perform operando neutron imaging experiments with full size cells.
Example: Imaging of the AutoStack-Core fuel cell (300 cm2 active area) at the NEUTRA beam line