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1	Mass Transfer and GDL Electric Resistance in PEM Fuel Cells Wang, Lin 11 November 2010 (has links) Many modeling studies have been carried out to simulate the current distribution across the channel and shoulder direction in a proton exchange membrane (PEM) fuel cell. However the modeling results do not show agreement on the current density distribution. At the same time, no experimental measurement result of current density distribution across the channel and the shoulder direction is available to testify the modeling studies. Hence in this work, an experiment was conducted to separately measure the current densities under the channel and the shoulder in a PEM fuel cell by using the specially designed membrane electrode assemblies. The experimental results show that the current density under the channel is lower than that under the shoulder except when the fuel cell load is high. Afterwards two more experiments were carried out to find out the reason causing the higher current density under the shoulder. The effects of the electric resistance of gas diffusion layer (GDL) in the lateral and through-plane directions on the current density distribution were studied respectively. The experimental results show that it is the through-plane electric resistance that leads to the higher current density under the shoulder. Moreover, a three-dimensional fuel cell model is developed using FORTRAN. A new method of combining the thin-film model and homogeneous model is utilized to model the catalyst layer. The model is validated by the experimental data. The distribution of current density, oxygen concentration, membrane phase potential, solid phase potential and overpotential in a PEM fuel cell have been studied by the model. The modeling results show that the new modeling method provides better simulations to the actual transport processes and chemical reaction in the catalyst layer of a PEM fuel cell.
2	Catalytic and Electrocatalytic Pathways in Fuel Cells Vilekar, Saurabh A. 19 April 2010 (has links) A fundamental understanding of the kinetics and mechanisms of the catalytic reaction steps involved in the process of converting a fuel into hydrogen rich stream suitable for a fuel cell, as well as the electro-catalytic reactions within a fuel cell, is not only conceptually appealing, but could provide a sound basis for the design and development of efficient fuel processor/fuel cell systems. With the quantum chemical calculations on kinetics of elementary catalytic reaction steps becoming rather commonplace, and with increasing information now available in terms of electronic structures, vibration spectra, and kinetic data (activation energy and pre-exponential factors), the stage is set for development of a comprehensive approach. Toward this end, we have developed a framework that can utilize this basic information to develop a comprehensive understanding of catalytic and electrocatalytic reaction networks. The approach is based on the development of Reaction Route (RR) Graphs, which not only represent the reaction pathways pictorially, but are quantitative networks consistent with the Kirchhoff's laws of flow networks, allowing a detailed quantitative analysis by exploiting the analogy with electrical circuits. The result is an unambiguous portrayal of the reaction scheme that lays bare the dominant pathways. Further, the rate-limiting steps are identified rationally with ease, based on comparison of step resistances, as are the dominant pathways via flux analysis. In fact, explicit steady-state overall reaction (OR) rate expression can also be derived in an Ohm's law form, i.e. OR rate = OR motive force/OR resistance of an equivalent electric circuit, which derives directly from the RR graph of its mechanism. This approach is utilized for a detailed analysis of the catalytic and electro-catalytic reaction systems involved in reformer/fuel cell systems. The catalytic reaction systems considered include methanol decomposition, water gas shift, ammonia decomposition, and methane steam reforming, which have been studied mechanistically and kinetically. A detailed analysis of the electro-catalytic reactions in connection to the anode and cathode of fuel cells, i.e. hydrogen electrode reaction and the oxygen reduction reaction, has also been accomplished. These reaction systems have not so far been investigated at this level of detail. The basic underlying principles of the RR graphs and the topological analysis for these reaction systems are discussed. methane steam reforming water gas shit ammonia decomposition hydrogen oxidation methanol decomposition electro-catalysis fuel cells reaction route graph theory oxygen reduction fuel cell model catalysis
3	Hybrid PEM fuel cell systems Gößling, Sönke, Smyrek, Felix, Bahr, Matthias 27 May 2022 (has links) Nowadays, PEM fuel cell systems for passenger cars are always realized as hybrid systems. If the architecture of a hybrid system is given, then the dimensioning of the fuel cell and battery subsystems is crucial in terms of costs, dynamics, and driving behavior in general. In order to analyze these dependencies correctly, the ZBT fuel cell model was integrated into a fuel cell system and a full vehicle simulation. The subject of the investigation is the interaction of different drive cycles, which in part are very different, with differently dimensioned sub models for the fuel cell system and the battery. The ZBT fuel cell model is integrated into the simulation environment AVL CRUISE™ M for the fuel cell system and the vehicle. An analysis is presented that compares the different drive cycles and system dimensions and provides specific recommendations for different use cases. info:eu-repo/classification/ddc/620 ddc:620 Brennstoffzelle
4	A Component-based Model of a Fuel Cell Vehicle System Salomonsson, David, Eng, Erik January 2021 (has links) Improving the efficiency and performance of vehicle propulsion systems has always been desirable, and with increasing environmental awareness this has become increasingly topical. A particularly strong focus today is at fossil-free alternatives, and there is a strong trend for electrification. Hybrid powertrains of different types can bring benefits in certain aspects, and there is a lot of research and development involved in the making of a new powertrain. In this thesis, a complete powertrain for a fuel cell hybrid electric vehicle is modeled, with the intention of contributing to this trend. The model can be used to investigate design choices and their impact on energy consumption. A component-based library is developed, with the purpose of being easy to implement for different configurations. The results show that it is possible to assemble and simulate a complete hybrid drivetrain, using the modeled components, while not being very computationally heavy. The developed models correspond well with reality while being modular and easy to implement. Fuel Cell Fuel cell Energy Efficiency Powertrain Control Propulsion Battery Supercapacitor Capacitor Compressor PEMFC Hydrogen Nitrogen pollution Purge valve Compressor Throttle Humidifier Fuel cell model Matlab Simulink Model Emissions PEM Mechanical Engineering Maskinteknik Elektroteknik och elektronik Energy Engineering Energiteknik Vehicle Engineering Farkostteknik Control Engineering Reglerteknik

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