Publications by Zacharie Wuillemin

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In order to link electrochemical performance degradation of the cathode in a large solid oxide fuel cell (SOFC) to the presence of pollutant species, a spatially-resolved study of contaminants was performed. Distribution maps of pollutants over the cell allowed to identify their sources. Besides chromium and silicon, sulfur was found as a major pollutant species. Its preferential reaction with strontium doped lanthanum cobaltite (LSC), forming strontium sulfate SrSO4, compared to strontium doped lanthanum m

This study aims to quantify in a holistic approach chromium (Cr) contamination in solid oxide fuel cell (SOFC) stack testing using adapted tools: i) a hot gas sampling method to analyze volatile Cr species in the air flux at the cathode inlet location; ii) a rapid quantification method for Cr as condensed matter in cathode material of post-test samples. The hot air sampling method reveals itself as a reproducible and time-resolved quantification technique for Cr trace amounts in a gas flow; this technique i

Solid Oxide Fuel Cells (SOFC) is an interdisciplinary technology by excellence, necessitating combined knowledge and R&D from mechanical, chemical, electrical and materials science engineering. At LENI Laboratory at EPFL, SOFC cells and stacks are designed, tested and analysed in collaboration with industry, from small area single cells to now kW-range stacks integrated in a system. The hardware R&D effort is strongly assisted by, and dependent on, modeling activities, for both design (e.g. new geometries)

This thesis focuses on performance, reliability and degradation in solid oxide fuel cells (SOFC), which currently represent the three key technical challenges for the deployment of this technology. By its development of dedicated modeling and experimental ...

Cell durability is a crucial technological issue for SOFC commercialization, and considerable progress has been made in recent years. A number of degradation pathways have been established, amongst which microstructural changes, poisoning effects and forma ...

The Laboratory for Applied Mechanical Design (LAMD) designed, manufactured, and experimentally tested a novel steam-driven anode off-gas recirculation (AOR) fan for 10 kWel solid oxide fuel cell (SOFC) systems. Due to the dynamic steam-lubricated bearings, the AOR unit is expected to have a high lifetime, even at elevated rotational speeds and temperatures. Additional, the unit is oil-free, explosion-proof, very compact, and cheap to manufacture. The AOR fan diameter is at 19.2 mm and the nominal rotational

Thermo-mechanical issues in solid oxide fuel cells (SOFC) must be understood and overcome to meet the reliability standards for market implementation. This study presents a thermo-mechanical model of an SOFC-stack SRU. The analysis starts with the simulati ...

The present invention concerns an SOFC system comprising an anode off-gas recirculation arrangement in which anode off-gas is pumped by a fan or pump of a coaxial turbine-fan assembly, the system comprising a condenser for condensing water contained in sai ...

The experimental validation of a real-time optimization (RTO) strategy for the optimal operation of a solid oxide fuel cell (SOFC) stack is reported in this paper. Unlike many existing studies, the RTO approach presented here utilizes the constraint-adapta ...

To improve the industry benchmark of solid oxide fuel cell systems (SOFC), we consider anode off-gas recirculation using a blower as an add-on to our next-generation SOFC system. Evolutionary algorithms compare the different design alternatives, i.e. co-flow or counter-flow stack operation with hot or cold recirculation. The system performance is evaluated through multiobjective optimization criteria, i.e. maximization of electrical efficiency and cogeneration efficiency. The results obtained suggest that i

Planar SOFC stack technology based on a unique concept (SOFConnex™) uses structured gas distribution layers between unprofiled metal sheet interconnects and thin Ni-YSZ anode supported electrolyte cells. The layers are flexible both in material and designa ...

State-of-the-art nickel-based SOFC anode-supported cells are highly sensitive to reoxidation of the metal phase at the temperature of utilization. This work presents results on redox stable nickel–YSZ (yttria- stabilized zirconia) anode-supported cells, fo ...

While the global fuel utilization of solid oxide fuel cells (SOFCs) is limited by the stack aging rate, the fuel excess is typically used in a burner, and thus limiting the system electrical efficiency. Further, natural-gas-fueled SOFCs require treated wat ...

Our SOFC stack development technology is based on the unique SOFConnexTM concept, using flexible gas distribution layers between metal sheet interconnect and thin ASE cells. Flexibility is given both in material and design. This ensures proper electrical c ...

After 10,000 h solid oxide fuel cell (SOFC) stack operation, the Cr-poisoning situation in (La0.6Sr0.4) (Co0.2Fe0.8)O-3 (LSCF)-based cathode material is depicted in this work. Systematic Cr profiling by energy-dispersive X-ray spectroscopy (EDS), from post ...

A method based on Monte Carlo simulations (MCS) is developed to assess the impact of manufacturing tolerances on the performance and reliability of solid oxide fuel cells (SOFCs). Computational fluid dynamics (CFD) simulations of the anode gas diffusion la ...

Zacharie Wuillemin

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Sulfur as Pollutant Species on the Cathode Side of a SOFC System

Multi-Scale Assessment of Cr Contamination Levels in SOFC Cathode Environment

Solid Oxide Fuel Cell

Experimental and modeling investigations on local performance and local degradation in solid oxide fuel cells

TEM investigation on zirconate formation and chromium poisoning in LSM/YSZ cathode

Design and Experimental Realization of a Steam-Driven Micro Recirculation Fan for Solid Oxide Fuel Cell Systems

Thermo-mechanical Reliability of SOFC Stacks During Combined Long-term Operation and Thermal Cycling

Sofc system with anode off-gas recirculation

Experimental Real-Time Optimization of a Solid Oxide Fuel Cell Stack via Constraint Adaptation

Towards the Next-Generation of Solid Oxide Fuel Cell Systems

Impact of Materials and Design on Solid Oxide Fuel Cell Stack Operation

Redox stable Ni–YSZ anode support in solid oxide fuel cell stack configuration

Experimental characterization of a solid oxide fuel cell coupled to a steam-driven micro anode off-gas recirculation fan

Experimental Real-Time Optimization of a Solid Oxide Fuel Cell Stack via Constraint Adaptation

PROGRESS IN STACK POWER DENSITY USING THE SOFCONNEX™ CONCEPT

Cr-poisoning in (La,Sr)(Co,Fe)O-3 cathodes after 10,000 h SOFC stack testing

Impact of Random Geometric Distortions on the Performance and Reliability of an SOFC

Determination of an electrochemical model from experiments on a segmented solid oxide fuel cell