  The dynamics of two-phase flow within the cathode of a proton exchange
membrane fuel cell, particularly in Gas Diffusion Layers (GDLs) with varying
fiber curvatures, remain underexplored. Using a periodic surface model, we
stochastically reconstruct three GDL types with different fiber curvatures,
incorporating vital parameters derived from a physical GDL. Considering the
randomness in reconstruction, the structure generation process is iterated four
times for each GDL type, enabling an ensemble average analysis. Pore network
models are adopted to reveal disparities in these GDL porous structures. The
subsequent two-phase simulations are conducted to explore liquid transport
through these GDLs and interfaces to assembled gas channels. Time-varying GDL
total, local water saturation, and capillary pressure are investigated. Results
show stochastic reconstructions exhibit similar frequency peak ranges in pore
and throat diameters, and coordination numbers, but diverge from the physical
GDL. Bigger fiber curvature tends to enhance pore network connectivity by
increasing smaller pores, leading to heightened water saturation and capillary
pressure. Straight-fiber GDLs, compared to curved-fiber GDLs, show greater
potential proximity to the physical GDL in terms of overall water saturation
and capillary pressure but are also accompanied by increased uncertainty.
Despite similar layer porosity, water saturation in the same layer of all
samples differs increasingly from the inlet to the outlet. Water breakthrough
and detachment near the GDL can induce significant water saturation instability
at the GDL and gas channel interface. Detached droplets in gas channels
connected with straight-fiber GDLs exhibit larger sizes and slower movement
than those in channels assembled with curved-fiber GDLs. These findings can be
utilized in future GDL design and optimization.
