Model based evaluation of water management and membrane hydration in polymer electrolyte fuel cell with reactant flow-field gradients

Understanding water dynamics in operating fuel cells by operando neutron tomography: investigation of different flow field designs

“…It should be noted that the transparent flow field shown for reference is the cathode side, and the MEA is not shown in the figures, but is located between the anode and cathode as can be seen by the light gray/white vertical strip in the yz orthoslice in figure 6(a). In general, in both the 400 mA cm −2 and 500 mA cm −2 current holds (figures 6(b) and (c), respectively), water formation is primarily in the upper half of the SS flow channels on the cathode side, which is in good agreement with the findings from numerical models developed by Padavu et al who predicted greater accumulation of water at the flow channel outlet [19]. Given that the cathode gas flow was in an upwards direction through the cell, it is clear that this upwards flow is competing with the effects of gravity (pulling water downwards through the cell), and the known pressure-drop effect [37] resulting in lower gas pressure/velocity at the end of the flow channel and greater water accumulation.…”

“…Modelling can solve some of the limitations of 2D radiography techniques, by building up a 3D picture of water dynamics inside flow channels [5,15,16,[19][20][21]. Examples include the comparison of straight and wavy channels done by Kaiser et al [22], who suggested that wavy channels can improve fuel cell performance and water removal, the work by Liao et al [23], who showed that inclusion of a sub-channel can improve water drainage in PEFCs, and the work by Niblett et al who developed two-phase models for droplet formation under varying flow conditions in straight channels [24].…”