Two-phase transport in the cathode of PEM fuel cell with a porosity-graded gas diffusion layer

  • Min-Hsing Chang, Department of Mechanical Engineering, Tatung University, Taiwan
  • Prof Falin Chen, Institute of Applied Mechanics, National Taiwan University, Taiwan
  • Dr Jung-Shun Tsai, Department of Mechanical Engeering, Yung-Ta Institute of Technology and Commerce, Taiwan
  • Mr Ping-Tso Hsieh, Institute of Applied Mechanics, National Taiwan University

    • Water management is quite important in the cathode side of PEMFC to avoid the accumulation of liquid water and enhance the oxygen transport for the improvement of cell performance. Numerous studies have devoted to investigating this two-phase flow problem. Recently, a novel design of gas diffusion layer (GDL) in which contains a micro-porous layer (MPL) has been proposed to provide better gas and water transport performance. Some experimental studies have found that the addition of MPL will form a porosity-graded structure across the GDL. Accordingly, we perform a theoretical analysis to investigate the two-phase transport in the cathode GDL of PEMFC with a porosity gradient in the GDL. The porosity gradient is formed by adding MPL with different carbon loadings on the catalyst layer side and on the flow field side. The multiphase mixture model is employed and a direct numerical procedure is used to analyze the profiles of liquid water saturation and oxygen concentration across the GDL as well as the resulting activation and concentration losses. The results show that a gradient in porosity will benefit the removal rate of liquid water and also enhance the transport of oxygen through the cathode GDL. The present study provides a theoretical support for the suggestion that a GDL with porosity gradient will improve the cell performance.