Diffusive and convective mass transportations in proton exchange membrane fuel cells with orientational flow channels having porous blocks

Abstract

ABSTRACT Orientational flow channels having baffles with proper shapes enhance the reactant transportation and facilitate improving the performance of proton exchange membrane fuel cells. For the purpose of further increasing reactant supply into the membrane electrode assemblies, blocks with different porosities can be constructed between baffles and gas diffusion layer surfaces. It has been known that using orientational flow channels having baffles with porous blocks can further enhance the reactant transporting, however, the transporting process of reactants from channels into gas diffusion layers includes diffusion and convection processes, and how the diffusion and convection transporting processes perform in such channel structure is still unknown, which is probably beneficial to better understanding the mass transferring strategy in the cells whose channel spaces are blocked. In the present study, a two-dimensional, two-phase, non-isothermal, and time-independent corrected model adding non-Darcy flow influence is employed to numerically study reactant and products transportation strategy by using orientational flow channels having porous-blocked baffles. The diffusion and convection of species are separately discussed. Simulation results reveal that by distributing blocks with different porosities, the convective flux of reactant is enhanced significantly, as a result, the main transporting approach switches to convection. However, produced water vapor removal is weakened due to porous blocks.