On 13th March 2020, Alexandra Pessot defended her thesis. Awarded by INP Toulouse, her work was realized both at Laplace and IRT Saint Exupéry, under the supervision of GEET doctoral school.
The high quality and the relevance of Alexandra’s thesis contributed to get significant results as a part of FUCHYA project.
THESIS SUBJECT
“Modeling of performances and ageing of low-temperature PEM fuel cells for aerospace applications”
About this thesis
Nowadays, fuel cells, and especially PEM fuel cells, are regarded as a promising solution for transportation applications, especially for the aeronautical sector in the context of development of a “More Electrical Aircraft”. Indeed, the integration of fuel cell systems in aircraft allows generating electrical energy with high efficiency and low environmental impact. However, there are still many questions about the performances and the durability of PEM fuel cells in typical aeronautical conditions. The thesis works are dedicated to the experimental study of PEM fuel cells developed especially for an aeronautical application and to the modeling of performances and aging of these components.
The first part of the thesis works is devoted to the study and the modeling of performances as a function of operating conditions. An experimental database has been created using the Design of Experiments method. Several PEM fuel cell stacks have been tested in a broad operating field, considering classic operating conditions but also operating conditions linked to an aeronautical environment. A particular attention has been paid to low pressure functioning, knowing that experimental investigations at subatmospheric pressures have revealed lower performances compared to a classic pressure functioning. The experimental results have been exploited via a modelling approach, with the objective to define a model for the polarization curve as a function of operating conditions. First, a curve by curve model, in which a set of parameters (exchange current density, parasitic reactions’ equivalent current density and diffusion resistance) has been determined for every polarization curve, has been proposed. In the next step, some assumptions concerning the parameter dependency to the operating conditions have been introduced within the model. Different variation laws expressing the parameters as a function of operating conditions have been proposed. In all these steps, the results show good agreement between the experimental polarization curve and the polarization curve estimated by the model in the complete operating field. The predictive behaviour have finally been investigated with polarization curves carried out at operating conditions taken inside (interpolation cases) or outside (extrapolation cases) the initial definition range of the Design of Experiments. The prediction for interpolation cases has given promising results whereas the prediction for extrapolation cases has appeared limited for “exotic” operating conditions like low pressure or low temperature functioning. Future works will be devoted to improve variation laws and thus predictions using the model.
The second part of the thesis works is dedicated to the study and the modeling of the ageing of a PEM fuel cell stack submitted to a given mission profile. The presented approach is based on the superposition principle which states that degradation caused by several solicitations is the sum of the degradations that would have been caused by each solicitation individually. A decomposition of the mission profile in different sub-missions is proposed, considering quasi-static sub-missions linked to the mission profile current levels and dynamic sub-missions linked to the current transitory phases of the mission profile and to the start and stop phases. In the thesis works, dynamic sub-missions are supposed to have a limited impact on degradation and are not considered. Three quasi-static sub-missions, it is to say three different current levels, have been tested on dedicated campaigns. Mission profile defined by the industrialist partner has also been tested. A rich experimental database has been obtained and has given interesting informations about the stack degradations as a function of different current solicitations. Different methodologies have been defined to apply the superposition principle, considering degradation evaluation on polarization curves or on “voltage versus time” curves. The obtained results have pointed out that the proposed approach seems relevant to estimate the cell voltage degradation: most of the time, estimation of voltage degradation due to the mission profile has shown a quite good agreement with experimental voltage degradation observed. However, the approach application to another mission profile has given more mixed results. Future works will be necessary to confirm the potential of this approach.
FUCHYA PROJECT
The characterization and modeling of mature aeronautical fuel cells for use on the ground and in the automotive industry. Evaluating new electro-mechanical couples.
JURY
| Sophie DIDIERJEAN | Rapporter | Professor / Université de Lorraine |
| Daniel HISSEL | Rapporter | Professor / Université de Franche-Comté |
| Marian CHATENET | Examiner | Professor / Université de Grenoble Alpes |
| Mathias GERARD | Examiner | Research Engineer / CEA |
| Christophe TURPIN | Thesis Director | Researcher / LAPLACE, Toulouse INP |
| Amine JAAFAR | Thesis co-Director | Lecturer / LAPLACE, Toulouse INP |
| Julien D’ARBIGNY | Invited | Fuel Cell System Expert / Alstom |
| Théophile HORDE | Invited | Research Engineer / Airbus |
| Marion SCOHY | Invited | Stack Designer / Safran |
| Fabio COCCETTI | Invited | Head of Competence Centre / IRT Saint Exupéry |
PUBLICATIONS
- Contribution to the modelling of a low temperature PEM fuel cell in aeronautical conditions by design of experiments – A. Pessot, C. Turpin, A. Jaafar, E. Soyez, O. Rallières, G. Gager, J. d’Arbigny – Mathematics and Computers in Simulation, vol. 158, pp. 179-198 – 2019 – DOI
- Development of an aging estimation tool for a PEM fuel cell submitted to a mission profile – A. Pessot, C. Turpin, A. Jaafar, E. Soyez, O. Rallières, J. d’Arbigny, N. Chadourne – FDFC 2019 (8th International Conference on ”Fundamentals & Development of Fuel Cells) – Nantes, France
- Construction d’un outil d’évaluation du vieillissement d’une pile à combustible PEM Basse Température soumise à un profil de mission – A. Pessot, C. Turpin, A. Jaafar, E. Soyez, O. Rallières, J. d’Arbigny, N. Chadourne – GdR HySPAC 2018 – Grenoble, France
- Contribution to the modelling of a Low Temperature PEM Fuel Cell in aeronautical conditions – A. Pessot, C. Turpin, A. Jaafar, G. Gager, J. d’Arbigny – ELECTRIMACS 2017 (12th International Conference on Modeling and Simulation of Electric Machines, Converters and Systems) – Toulouse, France
- Contribution to the modelling of a PEM-LT fuel cell in aeronautical conditions – A. Pessot, C. Turpin, A. Jaafar, G. Gager, J. d’Arbigny, C. Elleboode – FDFC 2017 (7th International Conference on Fundamentals & Development of Fuel Cells) – Stuttgart, Germany