Analytical and numerical analysis of PEM fuel cell performance curve

We present a novel approach for analyzing the experimental voltage-current curves of a polymer electrolyte membrane (PEM) fuel cell. State-of-the-art numerical models involve many poorly known parameters. This makes a comparison of numerical and experimental polarization curves unreliable. We suggest characterizing the cell by first using a simplified analytical model, which contains a minimal number of parameters and ignores three-dimensional (3D) effects. The resulting physical parameters are then used as input data for a 3D numerical simulation of the PEM fuel cell. Comparison of experimental, analytical, and numerical polarization curves enables us to estimate the contribution of 3D effects to the voltage loss. This procedure is performed using specially designed experiments, our recent analytical model, and the newest version of a numerical quasi-3D model of a cell. The results show that this approach may serve as a tool for the optimization of the flow field design. (c) 2005 The Electrochemical Society. All rights reserved

On the socio-technical potential for onshore wind in Europe : a response to Enevoldsen et al. (2019), Energy Policy, 132, 1092-1100

Acknoweldgements: S.W. and J.S. received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (reFUEL, grant agreement No. 758149). J.L. and T.T. received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 715132).Peer reviewedPostprin

Architectural Concept and Evaluation of a Framework for the Efficient Automation of Computational Scientific Workflows: An Energy Systems Analysis Example

Scientists and engineers involved in the design of complex system solutions use computational workflows for their evaluations. Along with growing system complexity, the complexity of these workflows also increases. Without integration tools, scientists and engineers are often highly concerned with how to integrate software tools and model sets, which hinders their original research or engineering aims. Therefore, a new framework for streamlining the creation and usage of automated computational workflows is introduced in the present article. It uses state-of-the-art technologies for automation (e.g., container-automation) and coordination (e.g., distributed message oriented middleware), and a microservice-based architecture for novel distributed process execution and coordination. It also supports co-simulations as part of larger workflows including additional auxiliary computational tasks, e.g., forecasting or data transformation. Using Apache NiFi, an easy-to-use web interface is provided to create, run and control workflows without the need to be concerned with the underlying computing infrastructure. Initial framework testing via the implementation of a real-world workflow underpins promising performance in the realms of parallelizability, low overheads and reliable coordination

Modelling of mass and heat transport in planar substrate type SOFCs

A mathematical model is presented that incorporates the mass transport by diffusion in the porous structure of thick substrate type solid oxide fuel cells (SOFCs). On the basis of the mean transport pore model a multidimensional study allows for an optimization of the structural parameters of the substrates with respect to cell performance. Next to the mass transport in the porous substrates the electrochemical kinetics, methane/steam reforming and shift reaction, and energy equations are integrated in the model and boundary as well as operation conditions can be varied. Two-dimensional simulations for both anode as well as cathode substrate type SOFC operating on partially prereformed methane are presented and discussed. (C) 2003 The Electrochemical Society

Verbundvorhaben Öko-effiziente Flugzeugsysteme für die nächste Generation (EFFESYS) - Teilprojekt Brennstoffzelle, Infrastruktur, Komponenten und System (BRINKS) - Schlussbericht

Der Einsatz von Brennstoffzellensystemen im Flugzeug bietet die Möglichkeit, die Funktionen Energieumwandlung, Wasser- und Inertgaserzeugung mit Hilfe eines einzigen Systems zu gewährleisten. Dadurch wird der Kraftstoffverbrauch verringert, die Gesamteffizienz eines Flugzeuges erhöht und ein emissionsarmer Betrieb von Flugzeugen besonders am Boden ermöglicht. Das Forschungszentrum Jülich hat im Rahmen dieses Vorhabens einen Beitrag zur technologischen Weiterentwicklung solcher Brennstoffzellensysteme geleistet. Die Arbeitsziele wurden in fünf Arbeitspaketen erarbeitet. Das erste Arbeitspaket hatte zum Ziel, ein experimentell getestetes Fuel-Processing System im 5 kWel.-Maßstab bestehend aus autothermem Reformer, Wasser-Gas-Shift Reaktor, katalytischem Brenner und den erforderlichen Balance-of-Plant-Komponenten zur Verfügung zu stellen. Im zweiten Arbeitspaket wurde eine Hochtemperatur-Polymer-Elektrolyt-Brennstoffzelle mit einer elektrischen Leistung von 5 kW entwickelt und getestet. Das dritte Arbeitspaket hatte das Ziel, ein integriertes System aus Fuel- Processing-Einheit und Brennstoffzelle aufzubauen und zu testen. Dieses System hat eine Leistung von 5 kWel. und ist mit synthetischem GTL-Kerosin betreibbar. Im vierten Arbeitspaket wurde ein autothermer Reformer entwickelt, konstruiert und gefertigt, der einen molaren Wasserstoffstrom liefert, der einer elektrischen Brennstoffzellenleistung von 50 kW entspricht. Außerdem wurde ein Wasser-Gas-Shift Reaktor in der gleichen Leistungsklasse entwickelt, konstruiert und gefertigt. Das fünfte Arbeitspaket lieferte Auslegungsdaten für ein Brennstoffzellensystem in der Leistungsklasse 50 kWel. bestehend aus Hochtemperatur-Polymer-Elektrolyt-Brennstoffzelle, autothermem Reformer, Wasser-Gas-Shift Reaktor und katalytischem Brenner