Bipolar plates / hydrogen fuel cells
In the context of the expansion of renewable or so-called “green” sources of energy, hydrogen is certainly playing a very prominent role. Storing hydrogen as a source of energy and transforming it into electricity involves fundamental development of new technologies. Bipolar plates, which fulfill important functions within hydrogen fuel cells, are just one small part of the big picture.
Functions of bipolar plates:
- They enable an electrical connection between fuel cells;
- They ensure cooling and sealing;
- They control the separation of gases between neighboring cells;
- They control the flow of the gases that are created through the transformation process via so-called current profiles.
Schematic of a hydrogen fuel cell
Bipolar plates are an integral component of hydrogen fuel cells, however, they are prone to damage and defects in the manufacturing process. These damages & defects may have severe negative effects on the functionality of the plates as seals or as conductors. It is, therefore, essential to detect damages & defects such as deformation, oxidation, air bubbles, or foreign material as early as possible.
NELA’s optical measurement and inspection systems can control the plates’ characteristics that are important for their functionality and can find any relevant defects. Because bipolar plates are profoundly reflective, they constitute a challenge for defect inspection involving optical systems such as cameras. This is why NELA uses Shape from Shading technology for the defect inspection. The SFS sensors are integrated in the inspection systems and fully embedded into the software algorithms.
Original: deformation is difficult to see due to reflection
SFS-image: gray value deviations can be detected reliably
Original: oxidation on sealing surface
SFS-image: gray values can be detected reliably
Original: air bubbles are mostly difficult to see due to reflection
SFS-image: defects are reliably detectable by deviating gray values