Polymer electrolyte membrane fuel cell pore network modelling

Gostick, J.T., loannidis, M.A., Fowler, M.W., and Pritzker, M.D. (2007) Pore network modeling of fibrous gas diffusion layers for polymer electrolyte membrane fuel cells. J. Power Sources, 173, 2TJ 29Q. 

Key words polymer electrolyte membrane fuel cell, PEMFC, two-phase transport, porous media, pore network model, lattice Boltemarm model, direct numerical simulation, macroscopic upscaling. 

The accumulation and distribution of licpiid water in the polymer electrolyte membrane fuel cell (PEMFC) is highly dependent on the porous gas diffusion layer (GDL). The accmnulation of liquid water is often simply reduced to a relationship between liquid water saturation and capillary pressure however, recent experimental studies have provided valuable insights in how the microstmcture of the GDL as well as the dynamic behavior of the liquid play important roles in how water will be distributed in a PEMFC. Due to the importance of the GDL microstmcture, there have been recent efforts to provide predictive modeling of two-phase transport in PEMFCs including pore network modehng and lattice Boltzmann modeling, which are both discussed in detail in this chapter. Furthermore, a discussion is provided on how pore-scale infonnation is used to coimect microstmcture, transport and performance for macroscale upscaling. 

Recently, pore network modeling has been applied to simulate the accumulation of liquid water saturation within the porous electrodes of polymer electrolyte membrane fuel cells (PEMFCs). The impetus for this effort is the understanding that liquid water must reside in what would otherwise be reactant diffusion pathways. It therefore becomes important to be able to describe the effect that saturation levels have on reactant diffusion. Equally important is the understanding of how the properties of porous materials affect local saturation levels. This requirement is in contrast to most continuum modeling of the PEMFC, where porous materials are treated with volume-averaged properties. For example, the relationship between bulk liquid saturation and capillary pressures foimd through packed sand and other soil studies are often employed in continuum models. ... 

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