Numerical study on effect of anisotropic permeability of porous electrodes on PEM fuel cell performance

The permeability of porous medium characterizes the ability of fluid flowing in the porous medium. The porous electrode of proton exchange membrane fuel cell consists of gas diffusion layer and catalytic layer, with the gas diffusion layer carrying the transport of the reaction gas and the catalytic layer being the main site of chemical reactions within the PEM fuel cell, both of which play a key role in the PEM fuel cell. In this paper, the effect of permeability in different directions within the porous electrode on the performance of PEM fuel cell was investigated in terms of polarization curves, oxygen distribution, and membrane water content distribution. It is found that under the same working conditions, the permeability in X-direction has the greatest influence on the PEM fuel cell performance and the PEM fuel cell performance is proportional to the magnitude of the permeability in X-direction, when the permeability in X-direction change to 0.1 and 0.2 of the original value, the PEM fuel cell performance decreases by 11.36% and 8.01%, and when the permeability in X-direction change to 5 and 10 of the original value, the PEM fuel cell performance increases by 10.18% and 13.79%. The effect of permeability in the Y-direction of porous electrodes on the performance of PEM fuel cells can be neglected. In porous electrodes, the PEM fuel cell performance reaches a peak when the permeability in the Z-direction of the gas diffusion layer is 1.18e-11 m2 and the permeability in the Z-direction of the catalytic layer is 2.36e-12 m2, therefore, increasing or decreasing the permeability in this direction leads to a decrease in the performance of the PEM fuel cell.