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Analyse et optimisation du fonctionnement de piles à combustible par la méthode des plans d'expériences

Abstract : Proton Exchange Membrane (PEM) Fuel Cell (FC) generators have some performances which strongly depend on the operating conditions linked with their environment. Moreover, the control of these systems is difficult because of the high number of physical parameters involved as the load current, the stack temperature, the pressures, the flows, the gas hydrations... The Design of Experiment (DoE) methodology can be used to define the tests that allow the rapid and efficient characterisation of the FC. The parameters that have the largest and most significant impacts on the generator behaviour can be determined, and some possible interactions between theses factors can be highlighted as well. The aim of the FC generator characterisation by the DoE method is to predict the system behaviour as a function of the operating parameters, and then to propose some control strategies for the optimisation of a relevant criterion like the output voltage, the fuel consumption, the maximal electrical power, or even the stack lifetime.
The PhD Thesis report is made of six chapters. After a brief overview of the PEMFC technology with its operating constraints (first chapter), the author provides some essential elements of the DoE methodology in order to make easier the work presented afterwards (second chapter). An experimental design is then proposed in order to evaluate the influences of the gas pressure and flow rate parameters over the maximal power of a 500W PEMFC operated in pressure regulation mode (third chapter). The full factorial design applied requires sixteen experiments. The analyses of variance made for this design and for the fractional design (composed of only eight experiments selected judiciously among the sixteen ones) lead to similar results, i.e. a major influence of the air flow factor over the maximal power reached by the studied FC. The tools and methods proposed in this first work are then developed and used to analyse some experimental data collected from a 5kW PEMFC (chapter four). The stack temperature, gas pressure and stoichiometry rate impacts over the fuel cell voltage are estimated for various load current levels. Some optimisations of the FC operation parameters leading to higher performances are performed thanks to numerical, statistical models. The fifth chapter is dedicated to the analysis of a durability test performed on a 100W PEMFC stack operated in steady-state conditions during 1000 hours. The study is made using the Response Surface Methodology (RSM) and it shows notably the interest of using some variable stoichiometry rates through the ageing time in order to obtain some high performances in term of FC voltage on the one hand, and lower cell voltage variability on the other hand. In the last chapter, the author shows how the DoE methodology can contribute to a deeper understanding of the physical phenomena encountered in the FC stacks. Three different domains are concerned: the pressure losses in the bipolar plates distributing the reactive gas flows inside the FC, the impact of humidification on the stack internal resistance, and finally the ageing of a stack operated at a temperature level higher than the nominal one.
The research work presented aims at showing that the experimental design method can be a suitable medium to characterise, to analyse and also to improve a complex system like a fuel cell generator.
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https://tel.archives-ouvertes.fr/tel-00163317
Contributor : Bouchra Wahdame <>
Submitted on : Tuesday, July 17, 2007 - 11:31:31 AM
Last modification on : Tuesday, October 27, 2020 - 2:34:29 PM
Long-term archiving on: : Monday, September 24, 2012 - 11:10:38 AM

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  • HAL Id : tel-00163317, version 1

Citation

Bouchra Wahdame. Analyse et optimisation du fonctionnement de piles à combustible par la méthode des plans d'expériences. Energie électrique. Université de Franche-Comté; Université de Technologie de Belfort-Montbeliard, 2006. Français. ⟨tel-00163317⟩

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