Ph'D defense Mlle Marwa OUERGHEMMI

Abstract : Proton Exchange Membrane Fuel Cells (PEMFC) are one of the most promising devices for the transition to green energy. They have emerged as alternative solution to fossil fuels contributing to the reduction of pollution.
However, there are still many challenges to be met to make their use widespread, including increasing their lifespan and optimizing their performance. Numerous studies have been carried out to solve these problems, without taking into account the mechanical state of the PEMFC and of the cell core in particular (MEA), which is the subject of this doctoral study.
The study is thus based on a dual experimental and numerical mechanical approach to predict the levels of stress and strain undergone by the core of PEMFC during hygrothermal cycling induced by the system operation.
New experimental methods have been developed to determine the mechanical properties of the different components of the PEMFC or its interfaces. As an example, the transverse isotropic mechanical behavior of different types of GDL was measured using tensile, shear and compression tests. A new methodology was also established to evaluate the frictional properties of MEA interfaces.
A numerical model was then developed, integrating the experimental data acquired in the previous parts, capable of predicting the stress and strain levels developing in the core of the cell under hygrothermal conditions similar to those imposed during the operation of a PEMFC.
This study has shown that the GDL properties do not have a significant influence on the mechanical response of the membrane. It would be possible to limit the plastic deformation of the membrane by imposing an assembly of the different elements of the PEMFC according to a fixed loading and by letting the different layers of the cell core slide in their plane. This theoretical result would guarantee a lower plastic deformation of the membrane, contributing in fine to a better durability of the cell.

Keywords: PEMFC, Mechanical behavior, Experimental methodology, Numerical modeling, Performance, Durability

Supervisors:
Patrice Mele
Christophe Carral

Jury members:
Patrice MELE
PROFESSEUR DES UNIVERSITES, Université Savoie Mont Blanc
Directeur de thèse
Olivier LOTTIN
PROFESSEUR DES UNIVERSITES, Université de Lorraine
Rapporteur
Denis CANDUSSO
DIRECTEUR DE RECHERCHE, Université Gustave Eiffel
Rapporteur
Assma EL KADDOURI
MAITRE DE CONFERENCE, Université de Lorraine
Examinatrice
Marian CHATENET
PROFESSEUR DES UNIVERSITES, Grenoble-INP
Examinateur
Yann MEYER
PROFESSEUR DES UNIVERSITES, Université Savoie Mont Blanc
Jean-François BLACHOT
DOCTEUR EN SCIENCES, CEA Liten
Invité
Christophe CARRAL
MAITRE DE CONFERENCES, USMB
Encadrant