Modélisation et simulation du transfert de l’eau dans les piles à combustible de type PEMFC

Soutenance de thèse Pierre Carrère

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Jeudi 28 novembre à 14h – Amphithéâtre Nougaro

Abstract :

Water management is considered as a key issue in order to improve Proton Exchange Membrane Fuel Cells efficiency and durability. One of the critical components regarding this issue is the cathode Gas Diffusion Layer (GDL).

In this context, the main goal of the PhD work is to improve the understanding of the mechanisms responsible for the liquid water formation and transport in the cathode GDL. To this end, a Mixed liquid-vapour Injection Pore Network Model (MIPNM) is developed. This new model enables one to simulate the liquid water formation and transport in the cathode GDL for a larger range of operating conditions (temperature, current density and channel relative humidity) than in previous works. Different regimes of water formation and transport are identified and described.

In a second part, the PhD work focus on the impact of the GDL hydrophobic treatment. Currently commercialized GDLs are rendered hydrophobic by coating Polytetrafluoroethylene (PTFE) onto the hydrophilic carbon fibres. It has been reported that the coating can be non-uniform on fresh GDLs and also that the coating can be altered during the operation of the fuel cell. The impact of these two phenomena on the liquid water distribution and on the reactant gas access to the catalyst layer is studied using the MIPNM for mixed wettability networks.

In a third part, a work aiming the improvement of PEMFC efficiency is developed. The goal is to optimise the reactant gas access to the catalyst layer by modifying the microstructure of GDLs. This is performed by coupling the PNM with a genetic algorithm. In a complementary study, improvement of the reactant gas access is studied through modifications of the GDL wettability properties.

Finally, a 1D model of the whole anode-cathode assembly is developed so as to take into account both anode and cathode operating conditions. This 1D model is coupled with the MIPNM in order to assess the impact of the anode operating conditions on the liquid water distribution in the cathode GDL.