Abstract
Following the concept developed in Part I of this study [ Y. Wang , J. Electrochem. Soc. , 156 , B1124 (2009) ], this paper deals with the two-phase transport in the porous-media channel for polymer electrolyte fuel cells (PEFCs). Two-phase flow in the channel plays a crucial role in both reactant supply and water removal for a high humidity operation. Based on the two-fluid description, we developed a two-phase transport model for the PEFC channel, and we further analytically obtained the profiles of the phase velocities, liquid/gas volume fractions, and pressures for both liquid and gas phases along the channel. We find that the impact of the capillary action can be neglected for the liquid transport along the channel. The prediction of liquid saturation profiles varies considerably when using different models of the relative permeabilities. A maximum liquid saturation of approximately 20% is predicted, which avoids the occurrence of a high transport resistance for gaseous reactants. Pores in the porous-media channel cannot be completely occupied by liquid due to the dominant interfacial forces among the phases. These benefits make the proposed porous channel approach superior to the traditional hollow channels in terms of two-phase transport characteristics.
Published Version
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