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ABSTRACT
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.
Nomenclature
| a | = | water activity |
| c | = | molar concentration [mol·m−3] |
| h | = | heat transfer coefficient [W·m−2·K−1] |
| iref | = | reference exchange current density [A·m−2] |
| k | = | thermal conductivity [W·m−1·K−1] |
| p | = | pressure [Pa] |
| u | = | velocity vector [m·s−1] |
| x,y,z | = | coordinate [m] |
| A | = | area [m2] |
| D | = | diffusion coefficient [m2·s−1] |
| F | = | constant of faraday [C·mol−1] |
| H | = | height [m] |
| I | = | cell current density [A·m−2] |
| L | = | length [m] |
| M | = | molar mass [kg·mol−1] |
| R | = | universal gas constant [8.314J·mol−1·K−1] |
| S | = | source term of governing equations |
| T | = | temperature [K] |
| V | = | potential [V] |
| W | = | width [m] |
| X | = | species mass fraction |
| Greek symbols | = | |
| = | transfer coefficient | |
| = | porosity | |
| = | stoichiometric flow ratio | |
| = | overpotential [V] | |
| = | membrane water content | |
| = | concentration index | |
| = | viscosity [kg·m−1·s−1] | |
| = | density [kg·m−3] | |
| = | electrical conductivity [S·m−1] | |
| = | potential [V] | |
| Superscripts | = | |
| a | = | anode |
| c | = | cathode |
Acknowledgements
This work was financially supported by the National Natural Science Foundation (Grant No. 52306090, 52076040) and China Postdoctoral Science Foundation (Grant No. 2023M731642).
Disclosure statement
No potential conflict of interest was reported by the author(s).
Additional information
Funding
Notes on contributors
Chaoling Han
Chaoling Han received a PhD degree from Southeast University in 202. Currently he is lecturer at Nanjing Tech University. He has published over 30 papers, mainly focusing on PEM fuel cells and energy storage.
Kang Shang
Kang Shang is currently enrolled as a Master student in Southeast University, China, since 2019. His research interests include PEM fuel cells simulation.
Zhenqian Chen
Zhenqian Chen is a professor and doctoral supervisor at the School of Energy and Environment at Southeast University, and the director of the Jiangsu Provincial Key Laboratory of Solar Energy Technology. In 1995, he obtained a doctoral degree in thermal engineering from Southeast University and stayed on as a teacher. He pursued postdoctoral research at the Hong Kong University of Science and Technology, Worcester Institute of Technology in the United States, the University of Washington, and the University of Toronto in Canada. During my tenure, I have published over 200 high level papers, including over 100 SCI papers.