PhD opportunities

Modelling operation and degradation of fuel cell systems for hydrogen mobility applications

Thesis proposal

Area of expertiseEnergétique et génie des procédés
Doctoral SchoolISMME - Ingénierie des Systèmes, Matériaux, Mécanique, Énergétique
SupervisorBEAUGER Christian
Co-supervisorAFFONSO NÓBREGA Pedro Henriqu
Research unitEnergétique et Procédés
KeywordsFuel cells, transportation, degradation, modeling, hydrogen, electric vehicle
AbstractContext and challenges
Hydrogen is viewed today as one of the main alternatives for reducing greenhouse gas emissions and other air pollutants from heavy-duty road transport [Peters2021]. In this context, the fuel cells which produce electricity from electrochemical reactions between hydrogen and oxygen in the air and thus power the electric motor (or even to charge a battery) are key components. However, the lifetime of the fuel cell remains an obstacle to the deployment of hydrogen for this type of application.
Indeed, during its life the fuel cells will be subjected to several types of degradation, reversible or irreversible, leading to more or less progressive and significant performance losses [Tognan2016]. Reversible degradation includes the oxidation of the catalyst, the drying out of the proton exchange membrane or the flooding of the porous electrodes. If not treated in time, initially reversible degradation can have irreversible effects. Among these irreversible effects, the agglomeration of catalyst particles, the oxidation of the catalyst support, the delamination of the membrane-electrode assembly or mechanical and chemical membrane degradation are the most common.
However, the occurrence of such degradation is closely linked to the operating conditions of the fuel cell [Vichard2021]. Thus, the strategies for controlling the various components of the system (compressor, cooling loop, humidification sub-system, anode recirculation loop, purge valves, etc.) and the the operating conditions (temperature of the stack and of the different reactant flows, pressure levels, flow rates, humidity, current profiles, etc.) will have a strong impact on the fuel cell durability.
In particular, during a cold start, when the ambient temperature is below 0 ° C, the formation of water in solid state within the fuel cell causes mechanical stresses which will have a severe impact on its lifetime. This problem is all the more prevalent in the case of automotive applications because starting must be able to be done quickly, with minimal energy consumption [Luo2018].
The aim of this thesis is to propose models at the systemic level making it possible to define management strategies, operating modes, start/shut-down/stand-by procedures (including cold start procedures) in order to lengthen the lifespan of these systems for heavy-duty transport applications. These models must not only make it possible to predict the occurrence of degradation mechanisms as a function of the operating conditions, but also, in the other direction, consider the state of health of the fuel cell in the prediction of its performance.
This thesis is part of the collaborative project Durability and Resilience of Fuel Cell Systems (DuraSys-PAC), which aims to improve the durability of fuel cell systems for heavy-duty mobility (targets of> 25,000 hrs. operation for buses and> 20,000 hours for trucks).

Scientific objectives
The main objective of this thesis is to develop system-level models integrating degradation aspects, with a prediction of the state-of-health of the fuel cell system and the impact of this state-of-health on its performance. These models will be suitable for real-time use (low computation time) and will have to integrate the various components of a fuel cell system (compressor, humidifier, cooling loop, etc.). Finally, these tools will have to be validated by comparison with experimental data (and also results from more detailed numerical models).
The developed models will pay particular attention to water management and cold start cycles.

Approach - Methods
 Literature review on fuel cell systems modeling, degradation phenomena, water management and cold start;
 Development of models in a programming language to be defined;
 Development of model validation protocols, identification of parameters, benchmark;
 Carrying out specific tests for the identification of parameters and/or experimental validation in our laboratory;
 Coordination and collaboration with project partners for data exchange, definition of protocols and co-construction of a common modeling platform.

Expected results
Validated numerical model for the study of a fuel cell system considering degradation issues.
ProfileTypical profile for a thesis at MINES ParisTech: Engineer and / or Research Master - Good level of general and scientific culture. Good level of practice of French and English. Good analytical, synthesis, innovation and communication skills. Qualities of adaptability and creativity. Educational capacities. Motivation for research activity. Coherent professional project.

Prerequisites (specific skills for this thesis):
Advanced knowledge in thermodynamics, fluid mechanics, heat transfer and / or process engineering. Strong skills in numerical modeling and scientific computing, with mastery of programming languages ​​such as Python, MATLAB, C ++ or Fortran. Motivation for experimental activity. Knowledge of heavy mobility, electric vehicle traction systems, electrochemistry and fuel cells will be a plus.

To apply: only by sending an email to pedro.affonso_nobrega@minesparis.psl.eu and christian.beauger@minesparis.psl.eu '
FundingContrat de recherche