Analysing operando 2D X-ray transmission images for liquid water distribution in polymer electrolyte fuel cells

X-ray imaging has been instrumental to the understanding of liquid water distribution in polymer electrolyte fuel cells (PEFCs) to inform water management strategies. In this work, rapid X-ray radiographic imaging is proposed as a complement to the more commonly used three-dimensional (3D) X-ray computed tomography for operando liquid water visualization. Operando radiographs offer an opportunity to expose liquid water distribution characteristics over a shorter time which may be elusive to 3D approaches. Using a sequence of microscale radiographs and developed analysis framework, additional insights on the operando liquid water dynamics are revealed, including breakthrough patterns and associated time-dependent characteristics. Results reveal an initial transient behaviour in the buildup of liquid water both in the volume and number of breakthrough points. Further analysis of breakthrough data shows that liquid water breakthrough points exhibit randomness with a persistence of about 54% of the observation time on average. These results show the capability of the proposed workflow which combines rapid imaging at high resolution with minimal intrusiveness and exposure damage using a relatively inexpensive lab-based technique. In combination with 3D imaging, the method presented will extend the capabilities of X-ray imaging for future PEFC liquid water visualization efforts.