Abstract : The Proton Exchange Membrane Fuel Cell (PEMFC) is a promising candidate for many applications particularly for the transportation in order to decarbonize this sector. Of the barriers, cost and durability represent two of the most significant challenges to achieving clean, reliable and cost-effective fuel cell systems. Proper management of the liquid water and heat produced in PEM fuel cells remains crucial to increase both its performance and durability. Indeed, large liquid water and temperature variations in the cell may accelerate long-term structural problems until irreversible degradation (membrane micro-cracks, pinholes, alteration of the catalyst chemical composition, etc.).
In this study, the complex theory of two-phase flow in PEM fuel cells is reviewed with a focus on the local volume-average of the conservation equations in a porous medium. From this theoretical analysis, two multi-physics and multi-component models are developed considering one-fluid and two-fluid dynamics to investigate the liquid water heterogeneities in large area PEM fuel cells. Both models consider the cell as a multi-layered system where each component is accurately in-plane discretized. This pseudo-3D approach is implemented in the commercial COMSOL Multiphysics® software to simulate a large-surface cell operation with a reasonable computing time while keeping the real flow-field design. Numerical results are compared to liquid water measurements obtained by neutron imaging for several operating conditions. The advantages and drawbacks of both models are discussed. In addition, a sensitivity study is performed to analyze some key parameters in the modeling of water transport mechanisms. Finally, the numerical water distribution is examined in each component of the cell with both models.
Composition du jury :
Mme Sophie DIDIERJEAN : Professeur des universités, Université de Lorraine, Rapporteure
M. Marc PRAT : Directeur de recherche, Institut de Mécanique des Fluides de Toulouse, Rapporteur
M. Laurent DAVOUST : Professeur des universités, Institut Polytechnique de Grenoble, Examinateur
M. Yann BULTEL : Professeur des universités, Institut Polytechnique de Grenoble, Directeur de thèse