| Summary: |
As promising power sources candidates for electrically powered vehicles, small-scale stationary power generators, and portable electronic devices,
proton-exchange membrane fuel cells (PEMFC), which electrochemically convert the chemical energy of a fuel directly into electrical energy with
high conversion efficiency, have received considerable attention. For the commercial success of PEMFC power sources, reliability and life (aging) are among the most important considerations. However, there is yet limited information available about failure modes for PEMFCs, and the causes and mechanisms of degradation are not fully understood. A better understanding of the phenomena in a membrane electrode assembly (MEA) is needed.
The power flow between the fuel cell and the electric load should be managed and optimized to satisfy the energy demands of the electronic devices. There are very few studies reporting the analysis of effect of inverter ripple current (transient electrical loads imposed by the power converter, DC/AC and DC/DC) on fuel cell performance. This is obviously a key topic when considering the commercialisation of a PEMFC due to the close relationship between the fuel cell energy management and the fuel cell aging.
The present project aims to study the aging phenomena of a fuel cell and to better understand its dynamic response. For that, the various components of a fuel cell will be fully characterized and the steady state and transient behaviours modelled using a phenomenological approach. The transient response of a fuel cell comprehends both kinetic phenomena, such as mass and proton transport and electrochemical reactions, but also slower response transient behaviours such as the redistribution of the MEA activity. The redistribution of the MEA activity occurs within few hours and the use of a segmented fuel cell allows studying this effect. The catalytic activity of the catalyst will be studied by carbon monoxide adsorption and the overpotential at  |
Summary
As promising power sources candidates for electrically powered vehicles, small-scale stationary power generators, and portable electronic devices,
proton-exchange membrane fuel cells (PEMFC), which electrochemically convert the chemical energy of a fuel directly into electrical energy with
high conversion efficiency, have received considerable attention. For the commercial success of PEMFC power sources, reliability and life (aging) are among the most important considerations. However, there is yet limited information available about failure modes for PEMFCs, and the causes and mechanisms of degradation are not fully understood. A better understanding of the phenomena in a membrane electrode assembly (MEA) is needed.
The power flow between the fuel cell and the electric load should be managed and optimized to satisfy the energy demands of the electronic devices. There are very few studies reporting the analysis of effect of inverter ripple current (transient electrical loads imposed by the power converter, DC/AC and DC/DC) on fuel cell performance. This is obviously a key topic when considering the commercialisation of a PEMFC due to the close relationship between the fuel cell energy management and the fuel cell aging.
The present project aims to study the aging phenomena of a fuel cell and to better understand its dynamic response. For that, the various components of a fuel cell will be fully characterized and the steady state and transient behaviours modelled using a phenomenological approach. The transient response of a fuel cell comprehends both kinetic phenomena, such as mass and proton transport and electrochemical reactions, but also slower response transient behaviours such as the redistribution of the MEA activity. The redistribution of the MEA activity occurs within few hours and the use of a segmented fuel cell allows studying this effect. The catalytic activity of the catalyst will be studied by carbon monoxide adsorption and the overpotential at each segment by impedance spectroscopy. The impedance study should allow to quantify the various overpotentials, including the proton conductivity of the catalyst layer.
The periodic characterization of a fuel cell when submitted to electric steady state and transient loads will allow to understand the various aging phenomena involved in a fuel cell. The model and simulator will be used together in the identification of the aging phenomena and in its quantification. |