ZHAW ICP Research Report 2012

Research Report 2012

Zurich Universities of Applied Sciences and Arts

r www.engineering.zhaw.ch

d Research & Development

Beispiel von Verschiebungen einer konischen Schale mit Durchschlagsverhalten und gewölbten Lösungen. Die konische Schale deformiert sich und nähert sich nach einer gewissen Zeit einer instabilen Region, in der die Schale durchschlagen kann. Erhöht sich die Verschiebung weiter, kommen wir zu einem Bifurkationspunkt, an dem gewölbte Deformationen auftreten.

Example of a conical shell displacements with snap-through and warp solutions. The conical shell starts to deform inward and after a while it approaches an unstable snap-through region, by further increasing the displacement, we arrive at a bifurcation point where warp deformations show up.

Contents Vorwort

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Preface

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1 Modeling and More 1.1 Simulation von Personenströmen als Kontinuum bei Grossanlässen und dichtem Personenverkehr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2 Materialcharakterisierung in der Lebensmitteltechnologie mittels Ultraschall-Verfahren 1.3 Neuartig optimierte Kühlprozesse zur nachhaltigen Herstellung von gefüllten Schokoladenprodukten mit verbesserter Qualität . . . . . . . . . . . . . . . . . . . . . . . .

1.4 Modeling the Cooling Curve of Soy Oil . . . . . . . . . . . . . . . . . . . . . . . . . .

1.5 Virtual Layout for Continuous Casting of Steel . . . . . . . . . . . . . . . . . . . . . .

1.6 Pore Clogging During a Long-Term Experiment with Bentonite Buffer Material: PoreSpace Percolation and Prediction of Air Permeability . . . . . . . . . . . . . . . . . .

1.7 A New Developped Method for the Optimization of the Adhesion Strength of Ceramic and Metallic Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.8 Automatic Ice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.9 Diagnostic Device for the Early-Stage Detection of Skin Cancer . . . . . . . . . . . .

1.10 Produktionskontrolle von Pulverbeschichtungen mittels thermischer Schichtprüfung .

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2 Fuel cells 2.1 Optimierung eines SOFC Brennstoffzellenmoduls . . . . . . . . . . . . . . . . . . . .

2.2 Leckagenanalyse im Hexis Brennstoffzellensystem . . . . . . . . . . . . . . . . . . .

2.3 Topological Analysis and FE-Simulation for the Study of Microstructure Degradation in Solid Oxide Fuel Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.4 Oxide Scale on Interconnectors after 40’000 Hours Fuel Cell Operation . . . . . . .

2.5 Relationships between 3D Topology and Reaction Kinetics in SOFC Electrodes . . .

2.6 Thin-Membranes Design in Micro-Solid Oxide Fuel Cell . . . . . . . . . . . . . . . .

2.7 Belenos Fuel Cell Stack: Simulation and Freezing . . . . . . . . . . . . . . . . . . .

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3 Energy Systems 3.1 Exploring and Improving Durability of Thin Film Solar Cells . . . . . . . . . . . .

3.2 Simulation of Hydrogen Production with a Photoelectrochemical Solar Cell . . .

3.3 Integration of High Temperature Electric Converter for Electricity Generation in Solide Oxide Fuel System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.4 Thermofluiddynamische Modellierung von Biomassevergasung . . . . . . . . . .

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4 Organic Electronics 4.1 Light Outcoupling from Organic Light-Emitting Diodes . . . . . . . .

4.2 From Atoms to Large-Area OLEDs -the IM3OLED Project . . . . . .

4.3 Erweiterung der Laborinfrastruktur zur Herstellung von Organischen am ICP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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30 . . . . . . . . . 30 . . . . . . . . . 31 Leuchtdioden . . . . . . . . . 32

Research Report 2012 Appendix A.1 Student Projects . . . . . . .

A.2 Scientific Publications . . . .

A.3 Book Chapters . . . . . . . .

A.4 News Articles . . . . . . . . .

A.5 Exhibitions . . . . . . . . . .

A.6 Conferences and Workshops A.7 Prizes and Awards . . . . . .

A.8 Teaching . . . . . . . . . . .

A.9 ICP-Team . . . . . . . . . . .

A.10 Spin-off Companies . . . . .

A.11 Location . . . . . . . . . . . .

Institute of Computational Physics

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Research Report 2012

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Vorwort Was haben Brennstoff- oder Solarzellen mit Schokolade gemeinsam ?

Alterungsprozesse spielen bei der Erforschung neuer funktionaler Materialien eine zentrale Rolle.

Wenn es zum Beispiel darum geht, Brennstoffe, Wärme oder Sonnenlicht direkt in elektrische Energie umzuwandeln, führen unerwünschte Alterungsprozesse häufig zu einer starken Abnahme der Effizienz. Typischerweise zeigen sich diese Alterungsprozesse in Veränderungen der mikroskopischen Beschaffenheit der Materialien, der sogenannten Mikrostruktur.

Experimentell lassen sich sowohl Alterungsprozesse als auch die Leistungsfähigkeit von Materialien gut abbilden. Mit der Hilfe von Rasterelektronen- oder Focused-Ion-Beam-Mikroskopen können 2D- oder 3D-Mikrostrukturaufnahmen erstellt werden. Und die Leistungsfähigkeit vieler Materialien lässt sich über Impedanzspektrokopie ermitteln. Gilt es jedoch, quantitative Veränderungen in der Mikrostruktur mit der daraus resultierenden Verminderung der Leistungsfähigkeit zu korrelieren, stösst die experimentelle Forschung an ihre Grenzen.

Hier kommen Computermodelle ins Spiel. Sie bilden die im Material ablaufenden Prozesse über physikalische Modelle ab. Dabei werden Mikrostrukturaufnahmen als Input verwendet, um daraus die Performance des Materials vorherzusagen. So helfen Modelle, Alterungsprozesse besser zu verstehen, Herstellungsprozesse zu optimieren und negative Materialeigenschaften von vornherein zu vermeiden. Das erklärt auch, was eine Brennstoff- oder Solarzelle mit Schokolade gemeinsam hat: In all diesen Materialien laufen Alterungsprozesse ab, die von der Mikrostruktur abhängen und über Computermodelle simuliert werden können.

Wie breit gefächert die Wissenschaftler des ICP forschen, erfahren Sie anhand des vorliegenden Jahresberichts 2012.

Auch in diesem Jahr möchte ich an dieser Stelle allen Mitarbeitern unseres Instituts für ihr grosses Engagement, ihre Begeisterungsfähigkeit und die tolle gegenseitige Unterstützung ganz herzlich danken.

Thomas Hocker Institutsleiter

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Preface What do fuel cells, solar cells and chocolate have in common ?

Aging processes play a key role in the development of new functional materials. For example, when converting fuel, heat or sunlight into electrical energy, undesirable aging processes often result in a large decrease in efficiency. Typically, these aging processes show up on very small scales within the materials, i.e. in transformations of its microstructure. Both aging processes and performance losses can be monitored experimentally. Using scanning electron and focused ion beam microscopy, 2D or 3D microstructure images can be taken. In addition, the performance of many materials can be determined using impedance spectroscopy. However, purely experimental approaches are insufficient to correlate in a quantitative manner the observed changes in microstructure to the resulting performance losses.

This is where our computer models come into play. Using these models we simulate the underlying aging processes based on physical laws to predict the resulting performance of the materials studied. Experimental microstructure data serve as input for the simulations. This way, modeling and simulation help us to better understand the aging of the materials – whether it be fuel cells, solar cells and chocolate. Anyway, as you will notice from the present Research Report 2012, our research covers a broad range of exciting topics.

At this point, I would like to take the opportunity to thank all the colleagues of our institute for their commitment, their enthusiasm and the great mutual support. Thank you very much.

Thomas Hocker Head of ICP

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Institute of Computational Physics

Simulation von Personenströmen als Kontinuum bei Grossanlässen und dichtem Personenverkehr

Contributors:

R. Axthelm

Partners: Funding: Duration:

ASE GmbH KTI 2013–2014 sonenbewegungen in grossen Dichten aufgestellt werden: Erstens wird die Geschwindigkeit eines einzelnen Individuums durch die benachbarten Personen und das Verhalten der Menge bestimmt. Zweitens haben die Fussgänger ein gemeinsames Ziel, das sie verfolgen. Und drittens nähern sich die Fussgänger auf dem direktesten Weg ihrem Ziel, wobei sie grössere Personendichten zu vermeiden versuchen. Anhand dieser drei Hypothesen lassen sich die Bewegung und die Dichteentwicklung der Menschenmasse als Kontinuum mit der folgenden Gleichung beschreiben %t + ∇ · (% u) = 0, wobei % für die Dichte und u für die vektorielle Geschwindigkeit der Personenmasse steht. Die betragsmässigen Grössen der Geschwindigkeitsvektoren sind in Form von empirischen Daten (Fundamentaldiagramme, s. Fig. 2) gegeben. Die Richtung wird dann durch Lage der Ziele und die Dichteverteilung bestimmt. Zum Modellansatz dazu gibt es Varianten in der Literatur.

Fig. 1: Street Parade in Zürich 2012 (Quelle: http://www.streetparade.ch)

Die Simulation von Fussgängerströmen soll zukünftig helfen, Grossveranstaltungen, wie z.B. die Zürcher Street Parade, so zu planen, dass auch in Paniksituationen keine Menschen zu Schaden kommen. Etablierte Multi-Agent Methoden sind nur auf kleine Menschenansammlungen anwendbar. Besser geeignet sind Kontinuums-Methoden, für die aber bisher keine kommerzielle Software erhältlich ist. Ziel des Projektes ist deshalb die Entwicklung einer Kontinuum basierten Software und deren Validierung durch Video-Analysemethoden.

Der Anwendungsbereich solcher Simulationsrechnungen lässt sich nicht nur auf andere Grossveranstaltungen wie z.B. Fussballspiele erweitern, sondern auch auf Planungen und Konzeptionierungen von Gebäuden wie Bahnsteige, Bahnhofs- oder Flughafenhallen.

Die Firma ASE ist spezialisiert auf videobasierte Erfassung von Personenströmen, agentenbasierte Simulation realistischer Szenarien und die ereignisorientierte Simulation der Auslastung von Serviceplätzen. Solche sogenannte mikroskopische Simulationen, die jeden Fussgänger einzeln darstellen, stossen bei hohen Personendichten schnell an Grenzen, so dass keine zuverlässige Analyse mehr möglich ist.

Makroskopische Modellansätze versprechen in solchen Situationen bessere Rechenergebnisse. Bis heute ist aber keine kommerzielle Lösung verfügbar.

Der makroskopische Modellansatz von Personendichten basiert zum einen darauf, die Menschenmasse als Kontinuum anzusehen und zum anderen auf drei Hypothesen die für Per-

Fig. 2:

(Quelle: Seyfried: Steps toward the fundamental diagram -

empirical results and modelling, 2007)

Qualitativ machen die theoretischen Ergebnisse der makroskopischen Modelle einen guten Eindruck. Allerdings wurden noch keine Methoden entwickelt, diese Ansätze auch quantitativ zu validieren. Für die praktische Anwendung der in der Forschung erarbeiteten Methoden ist eine softwaretechnische Umsetzung notwendig. Das im Projekt zu erarbeitende Software Tool soll dies ermöglichen. Zusätzlich wird der Ansatz im Entwicklungsprozess an Hand von gemessenen Personenströmen validiert werden.

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Abschlussbericht,Sonderfinanzierung,der,SoE, ,

,

,

Titel:' Materialcharakterisierung'mittels'Ultraschall4Verfahren'für'die' Prozessoptimierung'in'der'Lebensmitteltechnologie' Research Report 2012 Institute of Computational Physics Projektteam:' '

1.2 , ,

Thomas,Hocker,(ICP,,Projektleiter),

,

,

,

Materialcharakterisierung in der Lebensmitteltechnologie Olaf,Hoenecke,(IDP), , , Josquin,Rosset,(ZSN), mittels Ultraschall-Verfahren ,

,

Marcel,Rupf,(ZSN), Adrian,Fassbind,(ZPP,,nachträglich,zum,Projekt,gestossen), Contributors: T. Hocker Regula,Kramer,(ZPP,,nachträglich,zum,Projekt,gestossen), Partners: IDP-ZHAW, ZSN-ZHAW, ZPP-ZHAW , Funding: SoE-ZHAW , , , , , , , , , , Duration: 2012 Gesteckten'Ziele'

Ziel des Projekts ist die Entwicklung und Erpro- bensmittelprobe kann über ein Peltierelement Ziel,des,Projekts,ist,die,Entwicklung,und,Erprobung,eines,„UltraschallQDemonstrators“,,mit,dem,im, bung eines Ultraschall-Demonstrators, mit dem im Temperaturbereich 10 – 60 °C aufgeheizt Labor,in,Realzeit,die,Veränderung,von,Materialeigenschaften,von,Lebensmitteln,wie,z.B.,die, imKristallisation,von,Schokolade,detektiert,werden,kann.,Hierfür,sollen,Ultraschallsensoren,in, Labor in Realzeit die Veränderung von Ma- und abgekühlt und so ähnlichen thermischen terialeigenschaften von Lebensmitteln detek- Bedingungen wie in der Produktion ausgesetzt verschiedene,Konfigurationen,und,Anregungsmoden,über,die,Auswertung,von,SchallgeQ tiert werden kann – wie z.B. die Kristallisation werden. schwindigkeiten,und,Schallabsorptionen,in,der,Lebensmittelprobe,auf,ihr,Potential,hin,untersucht, von Schokolade.

Hierfür sollen Ultraschallsen- In ersten Versuchen wurde gezeigt, dass mit werden., soren in verschiedene Konfigurationen und An- hochfrequentem Luftultraschall ein neues VerErreichte'Ziele'über die Auswertung von Schall- fahren für Top-Down Messungen über der Leregungsmoden geschwindigkeiten und Schallabsorptionen in bensmittelprobe zur Verfügung steht (siehe der Lebensmittelprobe auf ihr Potential hin un- Fig. 2). Dieses neue Verfahren vermeidet die tersucht werden.

Schwierigkeiten einer konventionellen, direkten Schallankopplung über flüssige oder feste Medien. Letztere dehnen sich in typischen Lebensmittelherstellungsverfahren aufgrund von Temperaturänderungen aus oder ziehen sich zusammen und verfälschen so die Messungen.

Der für Luftultraschall erforderliche Dynamikbereich von 120 dB konnte allerdings bisher nur mit Laborgeräten mit entsprechender Sendeleistung und hoher Verstärkung der Empfangselektronik erreicht werden. Mit zusätzlichen Anpassungen der eingesetzten Wandler und der Elektronik (kürzere Pulsdauer bzw. höhere Frequenz) wäre eine noch bessere Separation der empfangenen Echos zu erzielen.

,

Fig. 1: Planung und thermische Auslegung des Fig. 2: Aufgebauter Ultraschall-Demonstrator und Der,UltraschallQDemonstrator,konnte,entsprechend,der,gemeinsam,erarbeiteten,Vorgaben,realisiert, Ultraschall-Demonstrators. erste Messergebnisse. Das Ultraschallecho veränund,für,erste,Untersuchungen,genutzt,werden.,Die,Abbildung,zeigt,oben,links,das,am,ZPP,erstellte, dert sich wähnend der Erstarrung der Schokolade.

Der Ultraschall-Demonstrator konnte entspreCADQModell,basierend,auf,der,thermischen,Auslegung,am,ICP,(exemplarisch,unten,links,dargestellt), chend der gemeinsam erarbeiteten Vorgaben Der Ultraschall-Demonstrator soll längerfristig 1, für den Einsatz in der studentischen realisiert und für erste Untersuchungen genutzt sowohl werden. Fig. 1 zeigt das am ZPP erstellte CAD- Ausbildung, als auch für MachbarkeitsanalyModell basierend auf der thermischen Ausle- sen als Basis für die Akquisition von zukünftigung am ICP und den Vorgaben an die Ul- gen Forschungsprojekten in der Lebensmitteltraschallsensorik von IDP und ZSN. Die Le- herstellung genutzt werden.

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Institute of Computational Physics

Neuartig optimierte Kühlprozesse zur nachhaltigen Herstellung von gefüllten Schokoladenprodukten mit verbesserter Qualität

Contributors:

L. Brenner, T. Hocker, T. Hunkeler, M. Suter

Partners: Funding: Duration:

IDP-ZHAW, ZSN-ZHAW, IFNH-ETHZ, Max Felchlin AG KTI 2012–2015

Das Projekt COOLCON hat zum Ziel, eine neuartige in-line Messplattform (basierend auf Ultraschall-, Temperatur- und Wärmeflusssensoren) in Kombination mit Multiphysik FEModellierung für die Analyse des transienten Erstarrungs- und Kontraktionszustandes von Schokoladenprodukten zu entwickeln. Die Messplattform und die Modelle sollen für die Optimierung der Kühlung der Schokoladenprodukte in industriellen Kühltunneln eingesetzt werden. Ziel ist die Verbesserung der Produktqualität unter gleichzeitiger Minimierung des Kühlenergieverbrauchs.

In der Schweiz wurden 2010 176’424 Tonnen Schokoladenprodukte hergestellt. Um diese in Formen gegossenen Produkte in Kühlprozessen zur Erstarrung zu bringen, bedurfte es bei einem Fettgehalt von ca. 30 % einer Kühlenergie von etwa 100 TJ (TeraJoule). Umfragen in der Schokoladenindustrie haben zudem gezeigt, dass zur Sicherstellung einer guten Ausformbarkeit der Produkte als häufige Massnahme eine Verlängerung der Produktverweilzeit im Kühlkanal um 20–40 % realisiert wird.

Jedoch kann bei Schwankungen in der Rohstoffqualität von Kakaobutter und entsprechenden Variationen in deren Kristallisationsneigung auch das Problem einer zu kurzen Verweilzeit im Kühltunnel auftreten. Dies führt zu einer Verschlechterung der Ausformbedingungen aufgrund einer unzureichenden Kontraktion des Produktes in der Giessform und damit zu Fehlproduktchargen.

Deshalb soll durch eine Messdaten- und Modellbasierte Analyse der Kühlbedingungen und deren Auswirkung auf die Produktqualität der negative Einfluss von Schwankungen in der Rohstoffqualität minimiert und das grosse Energieeinsparungspotential besser genutzt werden.

Erste Messungen wurden im Kühlkanal der Max Felchlin AG, Schwyz, durchgeführt. Fig. 1 zeigt die Anordnung der verwendeten Temperaturfühler. Die Fühler wurden an verschiedenen Stellen in der Schokolade, der Form und der Umgebung platziert. Die resultierenden Temperaturprofile sind in Fig. 2 dargestellt.

Fig. 1: Anordnung der T-Sensoren in Schokolade, Form und Umgebung.

Fig. 2: Abkühlkurven von Schokolade, Form und Umgebung im Kühlkanal.

Parallel dazu wurde das Abkühlverhalten der Schokolade modelliert, siehe Fig. 3. Je nachdem, ob die Änderung der inneren Energie u der Schokolade während der Erstarrung nur von T , oder von T und der Kühlrate dT /dt abhängt, ergeben sich qualitativ unterschiedliche T -Verläufe.

Fig. 3: Modellierter T-Verlauf der Schokolade im Kühlkanal.

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Institute of Computational Physics

Modeling the Cooling Curve of Soy Oil

Contributors:

M. Suter, T. Hocker

Partners: Funding: Duration:

Max Felchlin AG ICP-ZHAW 2012–2013

The crystallization properties of fats determines the melting behaviour, snap and gloss of chocolate and confectionery products. For a long time, the ”Shukoff cooling curve method“ has been applied in the food industry to analyze the crystallization properties of fats. The Shukoff method is a standardized procedure which describes the cooling of a properly melted fat in a standardized glass flask with a vacuum jacket.

The glass flass is positioned in a water bath, while the temperature of the fat is recorded with a Pt100 temperature probe, see Fig. 1.

probe and for water bath temperatures of 0 and 10 °C, respectively. Note that the simulated curve based on the global balance fits the data better than the curve obtained from the FEmodel. This is because the global model contains an adjustable fit parameter which the FEmodel does not. Furthermore, the FE-model is much more sensitive with respect to parameter variations such as the thicknesses of the glass walls of the used Shukoff flask, or the provided initial conditions.

After the successful validation of both models by experimental data, the main heat fluxes have been calculated. In Fig. 3, you can see from Jradiation,Wat that the thermal radiation between the soy oil probe and the surrounding cooling water is dominant – even at these rather low temperatures.

Fig. 1: Shukoff flask with melted fat sample and Pt100 probe. (Note that the flask is actually positioned vertically in a water bath.)

Fig. 3: Heat fluxes between the soy oil probe and its surroundings as obtained from the developed SESES FE-model.

However, the non-negligible conductive heat flux Jcon,Wat through the vacuum gap at vacuum pressures around 1 Pa indicates the presence of Fig. 2: Comparison of measured and simulated heat transfer by Knudsen flow. Finally, it is obviShukoff cooling curves of soy oil for water bath temous from the behavior of JAmbient that at cooling peratures of 0 and 10 °C. times above 40 minutes, heat flows from the ambient air above the cooling water level into the The objective of this work is to characterize probe. This leads to a stationary probe temperthe Shukoff apparatus from a thermodynamic ature which is above the cooling bath temperapoint of view. For this purpose, the cooling of ture, see Fig. 2. soy oil has been modeled by global energy bal- In future work, our modeling approach will be ancing and by solving the local heat conduc- extended to phase change materials such as tion equation using our in-house multi-physics cocoa butter and to other cooling curve apparaFE-software SESES. Fig. 2 shows the good tus such as tempermeters. This will help to betagreement between the measured and simu- ter understand the complex crystallization belated cooling curves for the considered soy oil havior of chocolate and confectionery products.

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Institute of Computational Physics

Virtual Layout for Continuous Casting of Steel

Contributors:

G. Sartoris

Partners: Funding: Duration:

SMS Concast, Numerical Modelling GmbH CTI 2012–2013

SMS Concast is an engineering company supplying heavy machinery and related technology for the production of long steel products as billets and blooms, which are subsequently transformed by rolling or forging into semi-final products. SMS Concast is selling combi continuous casters by exploiting its lead in casting process know-how and innovative customer-specific design solutions. The core components relevant for the steel-making processes as melting, refining and casting are designed and developed in Zürich and Udine (Italy). The scope of supply of SMS Concast comprises design, engineering and automation, supply of hardware, commissioning of single process elements up to complete melt-shops. Such melt-shops range in their capacity from ca. 150.000 tons/year up to 2.3 million tons/year for one process-line.

The company is acting world-wide and operates in the growth markets for steel with its own 100% owned daughter companies in Brazil, North America, Italy, India, China, Thailand and at European locations in England and Spain.

fort and deploy it already in the offering phase.

In addition, it will support R&D by identification of casting process limits and troubleshooting during installation and the after sales phase.

The continuous casting of steel includes a liquid phase inside the moving slab and a solidifying one at the exterior. The liquid phase can display a turbulent character whereas the solid one is subjected to elasto-plastic deformations. The strand is moving in a stationary way through rollers and at the same time is cooled by sprayed water. Numerical methods have to cope with solid and fluid phases transport, energy transport, mechanical contacts, radiation and cooling. Here a mixed Euler-Lagrange formulation should be used to model this multiphysics problem, the former one is the method of choice for fluids and the latter one for solids.

The challenging task is the capability to correctly track the evolution of the surface showing the phase transition, in short front tacking. A coupled thermal-mechanical computation is required here with an enthalpy function strongly non-linear at the phase transition. The solidified portion of the slab undergoes large plastic deformations and grows inwards from a thin layer to the full solid slab. For modeling the mechanical behavior of thin structures, shell elements are generally preferred. However, since the slab’s walls are standing growing in thickness, at some point one has to switch to generic solid elements, because the shell hypothesis is not valid anymore. To avoid this critical switching, one can opt to use stabilized solid elements of first order from the beginning.

Goal of this project is to provide the industrial partner SMS Concast with up to date software for modeling the continuous casting of steel.

In particular, our aim is to improve and adapt the NM-SESES multiphysics software to stateof-the art numerical algorithms as required for running optimized computations in the layout of continuous casting machinery. The NM-SESES software is already an advanced numerical tool for multiphysics modeling. It can solve in a coupled way almost all conservation laws of classical physics with generic coupling terms and material laws defined by the user as part of the problem specification. However, due to the complexity of the problem at hand, the problem specification for the continuous casting model is becoming a rather involved task. With this project, SMS Concast plans to improve the numerical simulation know-how developed in collaboration with NM Numerical Modelling GmbH during the past years. Optimized models and simulation concepts for the moving strand approach will enable SMS Concast to simulate casting processes closer to reality, with less ef-

Fig. 1 Steel blooms produced by SMS Concast continuous casters.

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Institute of Computational Physics

Pore Clogging During a Long-Term Experiment with Bentonite Buffer Material: Pore-Space Percolation and Prediction of Air Permeability

Contributors:

L. Keller, L. Holzer

Partners: Funding: Duration:

EMEZ-ETHZ (P. Gasser), EMPA (M. Rossell, R. Erni) NAGRA, SHARC 2012

Low-permeability geomaterials such as clay rocks and betonites are potential seal materials that should guarantee the safety of radioactive waste depositories. In addition, such geomaterials are reservoirs of natural gas, which were increasingly exploited during recent years.

Therefore, gas flow properties of such materials are of prime importance because, for example, gas pressure form corroding steel in radioactive waste depositories should be released via the intergranular pore space. Thereby, one of the most fundamental question is, at what properties (e.g. porosity) gas can flow trough the pore space and arrive at the other side of the system. By using a combination of high-resolution tomography, local porosity theory1 and classical percolation theory we provided information on fundamental transport properties such as the percolation threshold2 . In the following we present results related to one of the case studies that where performed at the ICP. The examined bentonite samples are from the longterm experiment, which simulates the behaviour of different seal materials under conditions of a high level radioactive waste depository.

The microstructure analyses document that extensive precipitation of amorphous material led to substantial changes of the pore structure. Energy dispersive X-ray spectroscopy performed in a transmission electron microscope shows that the amorphous material is enriched in Fe, Ca and Si, which indicates that Fe released from corroding steel reacts with dissolved species from the buffer material. Initially the porosity in the bentonite was in the range of 4.3–4.6 vol. % but due to precipitation and pore clogging the open porosity was reduced to < 1 vol. %.

Focused ion beam tomography in combination with a finite scaling approach was applied to the resolved pore space, which yielded percolation thresholds with critical porosities φc (Fig. 1).

After precipitation the residual open porosity is far below the percolation threshold. The original porosity of one sample was above the percolation threshold, but also in this material the percolation is restricted to one spatial direction.

This indicates an anisotropy with respect to percolation. Obviously, precipitation of new phases leads to pore clogging, which in turn affects gas permeability. Using results from pore-network modelling3 in combination with percolation theory illustrates that a minor reduction of porosity leads to a to substantial decrease in gas permeability. Depending on water saturation, air permeability decreases exponentially over three to four orders of magnitude within a narrow porosity range of about 1 vol. % (Fig. 2).

Fig. 1: Determination of percolation threshold φc Calculation of finite-size percolation probabilities λ(φ, L) are based on reconstructed pore spaces that were obtained from of FIB tomographic data. (a) Measuring pore connectivity in cells of different sizes L allows calculating finite-size percolation probabilities. (b) finite scaling of φmax (i.e. point inflection of λ(φ, L) with L−1/ν yielded percolation thresholds along different directions.

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Research Report 2012

Institute of Computational Physics tion S. The absolute permeability k0 and the critical volume fraction c for air percolation was calculated on the base of two-phase flow network modelling. (b) and (c) are illustrations of two principle steps in the network modelling workflow. (b) 3D reconstruction of the pore space after segmentation based on FIBnt. (c) Representation of the extracted pore network (also called skeleton), which is topologically equivalent to the segmented pore space in (b). Red balls correspond to pore bodies whereas grey sticks correspond to the pore throats.

Based on observations and calculations, gas transport along the integranular pore space of bentonites is not considered as a possible scenario and can reasonably be excluded for the residual open porosity after segregation of new phases.

Fig. 1: Prediction of gas permeabilities related to a pore space that is affected by changing porosities due to segregation of new phases. (a) Gas permeabilities ka (Ď&#x2020;) calculated for different values of water satura-

Literature: 1 Hilfer, R. 1991, Physical Review, 44, 60-75.

2 Keller et al. (subm.), J. Geophys. Res. 3 Valvatne, P. H., Blunt, M.J., 2004. Water Resources Research, 40, W07406.

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ZHAW

Research Report 2012

1.7

Institute of Computational Physics

A New Developped Method for the Optimization of the Adhesion Strength of Ceramic and Metallic Coatings

Contributors:

Y. Safa, G. Sartoris, T. Hocker

Partners: Funding: Duration:

IMPE-ZHAW (M. Terner, D. Penner, Ch. Scherrer, A. Jung) SoE–ZHAW 2012–2013

Thermal barrier coatings (TBC) are an essential technology in many industrial applications, from “macro applications” such as the ceramic coating on the metallic blades in gas turbines to MEMS (Micro-Electro-Mechanical-Systems) thin film deposition. Failure of such coatings occurs often at the coating-substrate interface.

Several experimental testing (shearing, tensile, or bending tests) have been suggested to evaluate the adhesion strength of the coats. Such methodes, however, are not applicable in general, especially for the evaluation of the remaining interfacial strength of actual coated components in gas turbine, because of the requirement of relatively large specimen.

An alternative non-destructive test is based on indentation (by Vicker or Knoop) applied on the interface of “small” coat-substrate sample.1 Moreover, the fracture toughness of the coat which is represented by the stress intensity factor Kc is obtained using empirical formulation with fitted parameters. An open question is still the applicability of such a semi-empirical approach for different material and loading conditions.

The main objective of this project is to develop a relevant material model to assess the intarface fracture toughness using physical parameters measured via X-ray diffraction (XRD), indentation testing and sophisticated numerical tools for the simulation of contact mechanics and crack propagation in various coating-substrate systems provided by current or past research partners. This is divided into three work packages: WP1- Indentation tests at the coating-substrate interface to produce cracking and provide a depth-load dependency, followed by microscopic imaging of the indented samples.

WP2- XRD measurement of residual stress in these samples.

WP3- Set up a numerical contact mechanics model (FEM) and a numerical crack propagation model by applying XFEM (eXtended Finite Element Method) and using input material data from WP1 and WP2.

Fig. 1: A road map for search space

X-ray diffraction using a new 1/4 circle Eulerian Cradle was used for residual stress (RS) analysis of the samples. The measurement parameters were established and good residual stress values were obtained for PVD-ZrN, TBC bondcoat layer, and welded Stellite 712 on steel. No significant residual stress was found in the top surface of the TBC ceramic YSZ layer, however the geometry did not allow accurate measurement at the interface. HOVF Cr2C3-NiCr hard coatings were not suitable for this XRD analysis.

Fig. 2: XRD spectra for YSZ coating: except for the 1 bondcoat peak indicated, all peaks are YSZ or substrate. Theoretical bondcoat peak positions are shown by green markers. (Performed at LKM by M. Terner)

A new indentation method is developed at the laboratory of metallic material LMM to perform

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Research Report 2012

Institute of Computational Physics

indentation tests along coating-substrate interfaces from 5 to 500 N, with both Knoop and Vickers indenters. The HOVF Cr2C3-NiCr hard coating was the most successful system tested, whereas the TBC and Stellite system could not produce reliable information.

Fig. 5: The results obtained at ICP are in agreement with experimental data at IMPE

Fig. 3: 3D confocal microscope image of indentations taken with Leica DCM 3D. The indentation is applied at the interface between YSZ coat and steel substrate using a Vickers indenter, for 14 micrometer depth. (Performed at LMM by Ch. Scherrer)

A contact mechanics model based on the FEM software SESES developed at ICP was extended to indentations on a bimaterial interface.

The numerical simulation was validated, since the obtained load-depth data are in good agreement with the values provided by indentation on superalloy sample.

Fig. 4: Simulation of superalloy sample under Vicker indentation using in-house developed SESES code.

A plastic deformation is shown in unloading stage

The resulting contact stress fields were successfully used to predict the crack initiation and propagation and to evaluate the fracture toughness in an advanced simulation based on XFEM (implemented in GetFEM package), see Fig. 6.

Fig. 6: Interface indentation crack in slice view: Simulation using XFEM and visualization using Paraview

Perspective: An implementation of advanced enrichment techniques in XFEM code representing the bimaterial interface crack should allow more accurate representation of the stress field in delamination problem. An iterative coupling of the solving step for crack growth and the contact solution at given indentation depth step should be a highly sophisticated approach of the crack growth under indentation. The fracture mechanics results obtained by solving a dynamic crack growth problem can be compared to the experimental data when acoustic emission techniques are synchronized with operational time step of the indentation machine.

Literature: 1 Yamazaki et al., Acta Metall. 24, No. 2, 109117 (2011).

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Research Report 2012

1.8

Institute of Computational Physics

Automatic Ice

Contributors:

R. Ritzmann

Partners: Funding: Duration:

ZPP-ZHAW Altira GmbH 2012–2013

In einer Vorarbeit wurde ein LED Bildschirm zum Einbau in Eisfelder von Eishockeyarenas entwickelt. Der Einbau und der damit verbundene schichtweise Eisaufbau, erwies sich aber als aufwändiger und lange andauernder Prozess. Die damit betrauten Mitarbeiter haben lange in der Kälte auszuharren.

Um den Vorgang zu automatisieren wurde in Zusammenarbeit mit dem ZHAW internen Zentrum für Produkt- und Prozessentwicklung ein serienreifer Automat erstellt (siehe Fig. 1).

keine Lufteinschlüsse und keine sichtbaren Schichtübergänge im fertigen Eis. Die Anlage wird zur Zeit im OLAB auf einer umgebauten Eiskühltruhe unter ähnlichen Bedingungen wie in der Eishalle betrieben um die Sensorik und Parameter zu optimieren (siehe Fig. 2).

Fig. 1: 3D Kontruktion, kompaktes Eis System zum automatischen Aufbau von klarem Eis

Automatic Ice enthält eingebaute Heiz- und Kühleinheiten und kann Luft und Wasser in vordefinierten Abläufen ins Eisloch spritzen.

Zuerst wird das Eis auf eine definierbare Tiefe abgeschmolzen und anschliessend schichtweise innerhalb von 4 mm/h wieder aufgebaut.

Den hohen Ansprüchen an die Eisqualität wird dabei Rechnung getragen. Es gibt also

Fig. 2: Labortests für optimierten Parametersatz

Mit Automatic Ice werden die LED-BildschirmModule oder auch Markierungen schnell einund ausgebaut.

Zusätzlich bietet es auch die Möglichkeit defekte Stellen, wie sie z.B. im Bereich der Eishockeytore häufig auftreten, über Nacht reparieren zu können.

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Research Report 2012

1.9

Institute of Computational Physics

Diagnostic Device for the Early-Stage Detection of Skin Cancer

Contributors:

M. Bonmarin

Partners: Funding: Duration:

Dermato Oncological Unit â&#x20AC;&#x201C; HUG Swiss Cancer League 2012â&#x20AC;&#x201C;2014

Incidence of skin cancers is very high in Switzerland and rising worldwide. Their prognosis depends on the precocity of diagnosis. Currently, the detection of skin cancer is essentially clinical and largely depends on the expertise of the clinician. Though, as early tumors often lack of specific signs, many benign lesions are excised to be on the safe side. Moreover, some skin cancers do not have visible limits, which can induce complex or multistep surgery. Therefore, detection and treatment of these tumors generate big health costs.

Compared to benign lesions, malignant tissues are expected to demonstrate specific thermal properties that can be exploited to refine their diagnosis. For example, a higher metabolic activity and a higher perfusion are anticipated at the location of the cancerous lesion. Such thermophysical variations can be accurately detected using active thermography based setups.

In close collaboration with the Geneva University Hospital (HUG), we develop a new highly sensitive infrared imaging technique for the detection of skin cancers. We plan to test this technique in order to define its actual limitations.

The device is based on the lock-in thermography method: skin surface temperature is periodically modulated by forced convection, while a highly sensitive infrared imaging device records its thermal emission (see Fig. 1 A)). Infrared images are then processed to a computer according to the digital lock-in principle. We expect that the amplitude and phase images resulting from this demodulation can be correlated to the le-

sion malignancy.

The first prototype developed in our laboratory (see Fig. 1 B)) shows promising results. An improved version will be tested in a clinical environment in summer 2013 at the University Geneva Hospital to evaluate the potential of the method.

Fig. 1: A) Pictorial description of the lock-in thermography setup. B) First Dermolockin prototype developed in our laboratory

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Research Report 2012

1.10

Institute of Computational Physics

Produktionskontrolle von Pulverbeschichtungen mittels thermischer Schichtprüfung

Contributors:

N. Reinke

Partners:

IDP-ZHAW, IGP-ZHAW, Winterthur Instruments AG, J. Wagner AG, Ronal AG, Ernst Schweizer AG, Ramseier Woodcoat AG (Ru) KTI 2012–2013

Funding: Duration:

Pulverbeschichtungen zeichnen sich besonders durch Korrosionsbeständigkeit und Kratzfestigkeit aus. Sie sind lösungsmittelfrei und werden besonders ressourcenschonend aufgebracht.

Schwer kontrollierbare Prozessparameter wie die elektrostatische Feldverteilung, Umgebungstemperatur und die definierte Körnigkeit des Pulvers wirken sich auf die Beschichtungsdicke aus, die bislang nur nach dem Einbrennvorgang zuverlässig geprüft werden kann. Verschwendung von Ressourcen und Beschichtungsfehler sind die Folge einer fehlenden Prozessprüfung bei der Beschichtung. Hohe Einbrenntemperaturen und -zeiten verursachen zudem hohe Energiekosten. Dadurch wird die Wirtschaftlichkeit von Pulverbeschichtungen im erheblichen Masse beeinträchtigt.

schichtungsanlagen, eine bessere Auslastung des Personals, eine Reduzierung der Beschichtungsdicke auf das Optimum und eine 100% Qualitätskontrolle. Das Messystem hilft das Verständnis des Einbrennvorgangs zu verbessern und ist damit ein Grundstein für ökonomisch und ökologisch optimierte Pulver mit verringerten Einbrenntemperaturen und effizienteren Einbrennprozessen. Als Grundlage für dieses Messsystem soll eine funktionstüchtige Pilotanlage entwickelt und deren Praxistauglichkeit bei Anwendungspartnern getestet werden.

Fig. 2: CoatMaster bei der Inline-Schichtdickenmessung von Pulverbeschichtungen.

Fig. 1: CoatMaster Messsystem.

Im Rahmen dieses Projekts soll ein marktnahes Messsytem entwickelt werden, welche eine Kontrolle der Beschichtungsdicke vor dem Einbrennen sowie des Gelier- und Aushärtegrads in der Produktion erlaubt. Dieses Messsystem erlaubt verkürzte Einfahrzeiten von Be-

Das Projektkonsortium umfasst die gesamte Wertschöpfungskette der Pulverbeschichtungsindustrie: Hersteller von Pulverlacken, Anlagenbauer, Messgerätehersteller, sowie die Anwender. Im Anschluss an das Projekt sollen Feldtests bei den Industriepartnern durchgeführt werden. Die Erkenntnisse dieser Feldtests fliessen in die Weiterentwicklung des Messsystems ein.

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Research Report 2012

2.1

Institute of Computational Physics

Optimierung eines SOFC Brennstoffzellenmoduls

Contributors:

T. Hocker, C. Meier

Partners: Funding: Duration:

IEFE-ZHAW (P. Diggelmann), Hexis AG Bundesamt für Energie, Swiss Electric Research 2012–2014

Zur Reduktion von Material- und Montagekosten entschied sich die Firma Hexis AG zur Neukonstruktion ihres Brennstoffzellenmoduls (BZM). Dabei stand nebst der Vereinfachung der Konstruktion auch die Verbesserung der Temperaturverteilung im Zentrum.

In das Hexis-BZM sind nebst den elektrischchemischen Komponenten (Zellstack und Reformer) auch wärmetauschende Elemente integriert, welche die Betriebstemperatur sowie die Temperaturgradienten an der Zelle kontrollieren. Durch diese Bauweise kann das HexisSystem zwar kompakt gebaut werden, dafür sind die auftretenden Wärmeströme schwerer zu verstehen und zu kontrollieren. Die thermisch-fluidische Auslegung des neuen Designs wird deshalb vom ICP, zusammen mit dem Institut für Energiesysteme und FluidEngineering (IEFE) der ZHAW, durch Modellbildung unterstützt.

In der Konzeptphase konnten wir durch die Analyse der Massen- und Energieströme, die Charakterisierung der wesentlichen Systemkomponenten sowie die Abbildung des BZMinternen Wärmetauschernetzwerkes einen optimalen Betriebspunkt identifizieren. In einem nächsten Schritt erstellte das IEFE eine dreidimensionale Strömungssimulation, welche die

Firma Hexis experimentell validieren konnte. Dieses numerische Modell berechnet das Strömungs- und das Temperaturfeld unter Berücksichtigung von Strahlungswärmetransport.

Der Brennstoffzellenstack wird optimal bei einer Temperatur von 850 ◦ C betrieben. Bei höheren Temperaturen führen Alterungsprozesse zu einer erhöhten Degradation des elektrischen Wirkungsgrades, während bei niedrigeren Temperaturen die inneren elektrischen Widerstände der Zellen sehr hoch sind. Deshalb sollte auch die axiale Temperatur-Ungleichverteilung ("T-Bauch") vermindert werden (siehe Fig. 1), um den ganzen Stack im optimalen Temperaturfenster betreiben zu können.

Anhand der Simulation des Ist-Zustandes konnten wir zeigen, dass der T-Bauch wesentlich durch die Führung der Verbrennungsluft beeinflusst werden kann. Zusammen mit Hexis haben wir eine Vielzahl an Designs entworfen, simuliert und optimiert. Ende 2012 wurde das vielversprechendste Konzept an einem Versuchsaufbau getestet. Trotz einer wesentlich einfacheren Konstruktion resultierte eine Reduktion des T-Bauches von rund 60 %. Gleichzeitig verbesserte sich die Effizienz der thermischen Isolation markant.

Fig. 1: Temperatur-Plots der Referenz- und einer optimierten Variante. Der Zellstack der optimierte BZMVariante weist einen geringeren Temperatur-Bauch auf.

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Research Report 2012

2.2

Institute of Computational Physics

Leckagenanalyse im Hexis Brennstoffzellensystem

Contributors:

L. Kaufmann

Partners: Funding: Duration:

Hexis AG Swiss Electric Research, Bundesamt für Energie 2012–2014 (<1000 h) Zellen mit einer definierten Vorschädigung in Form von Schlitzen und Brüchen mit intakten Zellen verglichen. Zur Charakterisierung des Zellverhaltens wurden StromSpannungskennlinien aufgenommen. Es zeigt sich, dass zur Detektion eines Zelldefekts ganze Strom-Spannungskennlinien betrachtet werden müssen. Es reicht nicht aus, einzelne Merkmale wie zum Beispiel die Ruhespannung (OCV) zu betrachten. Leichte Zelldefekte wie einfache Risse lassen sich im Hexis-System in der Regel nicht über Strom-Spannungskennlinien detektieren. Bei schweren Schädigungen (0.8 mm breite Schlitze) sind die Auswirkungen auf die Kennlinien deutlich erkennbar.

Ruhespannung 1100 intakte Zelle Zelle mit Schlitz

1000

Spannung / mV

Die Hexis AG in Winterthur (ehemals Sulzer Hexis) entwickelt ein mit Erdgas betriebenes Hochtemperaturbrennstoffzellensystem vom Typ SOFC (Solid Oxide Fuel Cell) zur stationären Strom- und Wärmeerzeugung in Einfamilienhäusern. Die Langlebigkeit und Zuverlässigkeit dieses Systems hängt unter anderem massgeblich von der Stabilität der zur elektrischen und thermischen Energieerzeugung verwendeten Brennstoffzellen ab. Für stationären Brennstoffzellensysteme ist ein entscheidender Erfolgsfaktor das Erreichen der geforderten Lebensdauer von 40’000 Betriebsstunden. Im Betrieb werden Brennstoffzellen durch thermische, chemische und auch mechanische Belastung beansprucht. In Folge dessen nimmt der elektrische Wirkungsgrad des Systems mit zunehmender Betriebsdauer ab. Diese Leistungsdegradation wird beschleunigt, wenn eine Leckage, z.B. durch eine defekte Dichtstelle oder einen Zellriss, auftritt. Dies kann auch kurzfristig einen Einfluss auf die Leistung des Brennstoffzellensystems haben.

900 800 700 600 500 0

5

10

15

20

25

Strom / A

Fig. 2: Vergleich der Strom-Spannungskennlinien von intakten und vorgeschädigten Zellen. Die intakte Zelle weist eine deutlich höhere Ruhespannung auf als die Zelle mit Schlitz. Zudem fällt die Kennlinie der vorgeschädigten Zelle steiler ab, was sich negativ auf den Innenwiderstand der Zelle auswirkt.

Fig. 1: Brennstoffzelle mit Vorschädigung. Der Zelle wurde ein radial verlaufender Schlitz hinzugefügt.

Dies ist eine extreme Schädigung. Es ist unwahrscheinlich, dass im Betrieb so starke mechanische Schäden auftreten.

Um herauszufinden, wie sich mechanische Zellschädigungen auf das Verhalten des Systems auswirken, wurden in Kurzzeitversuchen

Im Betrieb kann davon ausgegangen werden, dass keine Schädigungen dieses Ausmasses (Schlitze von 0.8mm Breite) bei Zellen auftreten.

Es bleibt festzuhalten, dass diese Aussagen nur für Kurzzeitversuche zutreffen. In Langzeitversuchen ist zu erwarten, dass durch die Defekte verstärkte Zellschädigungen wie z.B. Delamination und/oder übermässige Degradation der Elektroden auftreten und somit die Leistungsdegradation merklich zunimmt.

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Research Report 2012

2.3

Institute of Computational Physics

Topological Analysis and FE-Simulation for the Study of Microstructure Degradation in Solid Oxide Fuel Cells

Contributors:

L. Holzer, L. Keller, O. Pecho, M. Neumann, T. Hocker

Partners: Funding: Duration:

Hexis SA, EMPA, EMEZ-ETHZ, FZ-Jülich (De), Ulm University (De) EU-FP7 (Project: SOFC-life) 2012–2014

Solid Oxide Fuel Cell (SOFC) systems represent an environmentally friendly energy technology that efficiently converts chemical energy from natural gas into electricity and heat. In order to be economically profitable a service life of 40’000 hours must be reached. The complex phenomena of materials degradation are investigated in the SOFC-life project by a European consortium, which consists of 20 academic and industrial partners. The aim of the project is to gain an improved understanding of the degradation mechanisms on a microscopic scale and of their impact on cell and stack performances on a macroscopic scale. This will enable to improve durability, which also leads to a higher profitability. In this project, the ICP is working on the quantitative 3D characterization of the electrode microstructure. The ICP also deals with the challenging task, how this microstructure information can be incorporated into a simulation framework that allows prediction of the long-term degradation behavior.

Fig. 1: Illustration of microstructure degradation in a fine-grained Ni-YSZ anode upon redox cycling at 900 ◦ C. The effective ionic conductivity is the product of the intrinsic conductivity multiplied by the microstructure factor (σef f = σ0 M ). The M-factor itself is the product of four distinct topological parameters (M = φP βτ −1 ). The most significant microstructure effect in this case is a significant drop of the constriction factor (β), which strongly affects M and σef f .

In order to understand microstructure effects related to electrode degradation it is necessary to identify all topological features, which

have a significant influence on the cell performance. For this purpose dedicated techniques for 3D analysis including image modeling and nanotomography were developed over the last years. Fig. 1 illustrates the topological changes in YSZ of a Ni-YSZ anode before and after redox degradation. In each phase the effective transport properties (i.e. electronic conductivity in Nickel, ionic conductivity in YSZ, gas diffusion in the pores) depends on four distinct parameters: phase volume fraction, percolation factor, tortuosity and constrictivity. Surprisingly, the ionic conductivity drops significantly upon redox cycling due to a decrease of the constrictivity in the YSZ phase. This new phenomenon has not been documented in literature and the perception of it was only possible with new 3D-techniques.

In a second step the topological information is incorporated into a finite element model (FEM).

The detailed 3D analysis tools provide a quantitative description not only of time dependent degradation of the bulk electrode, but also of the local microstructure variations within different domains of the electrodes. For example the above-described constrictivity parameter only becomes important for transport distances larger than a few microns, but it has no effect at short distances. In the FE-simulation the distinction of such short and long rang effects has a significant influence on the current distribution close to the electrode-electrolyte interface and on the corresponding cell performance (ASR).

In summary, the combination of 3D-topological analysis with FE-modeling provides a unique framework for the realistic simulation of SOFC degradation.

These methodologies provide novel insight on fundamental degradation mechanisms, which is necessary for further improvements of the long-term service life of the solid oxide fuel cell system.

Literature: L. Holzer et al., J. Mat. Sci. 48, 2934-2952, 2013.

L. Holzer et al., J. Power Sources (in press), 2013.

G. Gaiselmann et al., Comp. Mat. Sci. 67, 4862, 2013.

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Research Report 2012

2.4

Institute of Computational Physics

Oxide Scale on Interconnectors after 40’000 Hours Fuel Cell Operation

Contributors:

M. Linder, L. Holzer, T. Hocker

Partners: Funding: Duration:

Hexis SA Swiss Electric Research, Swiss Federal Office of Energy 2012–2014

To provide a technical relevant amount of electrical energy several fuel cells have to be stacked.

These cells are connected in series with metallic interconnects (MICs) which act as gas separators and distributors for cathode air and anode fuel as well as current collectors from these electrodes (cf. Fig. 1). Interconnects have to fulfill different material requirements such as excellent oxidation and corrosion resistance and high electric conductivity. Under solid oxide fuel cell (SOFC) operating condition with high temperature (> 600 ◦ C), wet and carbon containing atmospheres the oxide scale formation is continually promoted.

LSM coating

cathode side air channels (O2, N2) cathode

Cr2O3 scale Cr5FeY2O3 (CFY) Cr2O3 scale Ni mesh

anode anode side fuel channels (H2, CO, H2O, CO2, N2, CH4)

Fig. 1: MIC configuration within a SOFC-stack. On the anode side the Cr2 O3 formation takes place at the bare surface and on the cathode side between the alloy and LSM-coating.

The ohmic resistance caused by Cr2 O3 scale formation on metallic interconnects can significantly contribute to the overall degradation of SOFC stacks. For this reason oxide scale growth on Cr5Fe1Y2 O3 (CFY) was investigated by scanning electron microscopy (SEM) from post-test samples that were operated in Hexis planar SOFC-stacks under dual atmospheres (i.e. anode and cathode conditions) at temperatures around 900 ◦ C. The study includes unique test results from a stack operated for 40’000 hours. To analyze the inhomogeneity in scale thicknesses a dedicated statistical image analysis method has been applied (cf. Fig. 2).

Fig. 2: (Top) SEM image of a cross section of a metallic interconnect after 2’000 h exposure (850 ◦ C in air). The perimeter of the Cr2 O3 scale is marked by a red contour line. (Bottom) From the segmented and binarized SEM image a mean scale thickness is calculated.

SEM images were as well used to compare the qualitative micro-structural phenomena related to MIC oxidation at different sample locations. The observed differences between different sample locations may relate to locally different conditions such as temperature and water content. The Cr2 O3 scale growth on the anode side is found to be approximately twice as fast in comparison to the scale growth on the cathode side. Finally, based on our time lapse analyses with extensive sampling it can be concluded that reliable predictions of scale growth requires statistical analyses over a period that covers at least a quarter (i.e. 10’000 hours) of the required SOFC stack life time (40’000 hours).

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Research Report 2012

2.5

Institute of Computational Physics

Relationships between 3D Topology and Reaction Kinetics in SOFC Electrodes

Contributors:

O. Pecho, L. Holzer, T. Hocker

Partners: Funding: Duration:

IfB-ETHZ, NonMet-ETHZ, EMEZ-ETHZ, Hexis AG, EMPA, Ulm University (De) Swiss National Science Foundation 2012â&#x20AC;&#x201C;2014

Solid oxide fuel cells (SOFC) represent an attractive, alternative energy technology due to the combination of its high efficiency and fuel flexibility. This project investigates the microstructure-performance relationships, in order to establish criteria for new microstructure concepts of improved SOFC electrodes. This goal requires an interdisciplinary approach involving: (a) electrode fabrication with controlled variation of the microstructure; (b) quantitative analysis of microstructure involving first and higher order topological parameters; (c) experimental characterization of macroscopic properties focused on the electrochemical performance; and (d) FE modeling of the electrode reaction mechanism including the simulation of combined effects from local morphology (microstructure) and from intrinsic material properties (e.g. surface exchange kinetics).

Fig. 1: Microstructures obtained at different sintering temperatures, which lead to variations in grain and pore size, surface area and associated electrochemical performance.

In the first period of the project, thin nanoporous cathodes consisting of (La,Sr)CoO3 (LSC) were successfully produced with the cost-effective spray pyrolysis. LSC is a mixed ionic and electronic conducting material (MIEC) that is particularly suitable for intermediate- and lowtemperature SOFCs. Overall, the LSC cathodes exhibit a very good performance, which is attributed to the nanostructure with small particle size and well-distributed porosity. This is favorable for oxygen exchange at the LSC/air inter-

face, which is believed to be the rate determining process. Figure 1 illustrates LSC cathodes with different microstructures. In order to better understand the complex relationship between microstructure and electrode performance, the experimental investigations are combined with 3D analysis and with numerical simulations.

First order topological parameters (e.g. particle size distributions (c-PSD), volume fractions, and surface areas) are determined based on 2D SEM imaging. For higher order topological parameters, (e.g. percolation factor, constrictivity, tortuosity) 3D information is needed.

FIB-tomography, which is the most suitable 3Dtechnique for this purpose, is time consuming and the number of 3D analyses is limited. In order to acquire 3D topological information for a large number of different microstructures, new approaches based on the combination of 2D imaging and stochastic 3D simulation are currently developed for this study in collaboration with Empa and Ulm University.

In the present project the reaction mechanism of an existing FE-model at ICP is adapted for MIEC materials. For the simulation of microstructure effects, input is used from microstructure analysis (i.e. surface area, TPB, tortuosity, constrictivity) and the effective transport properties.

Special techniques were developed, which allow the determination of effective transport properties from topological analysis because the experimental measurement is often very difficult (e.g. ionic conductivity of MIEC materials or gas diffusivity in nanoporous thin films). In this way different scenarios for microstructure effects can be simulated in a realistic way, which helps to understand the complex pattern revealed by the experimental investigations.

In summary, the combination of experimental investigations together with 3D-imaging, stochastic simulations and numerical modeling opens new possibilities to make links between topology, fabrication parameters and electrode performance. These methods shall thus be applied in the next phase of the project for the improvement of LSC cathodes as well as for other composite electrodes.

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2.6

Institute of Computational Physics

Thin-Membranes Design in Micro-Solid Oxide Fuel Cell

Contributors:

Y. Safa, T. Hocker

Partners: Funding: Duration:

NIM-ETHZ, LTNT-ETHZ, CSEM, SAMLAB-EPFL, MNT-NTB Swiss National Science Foundation 2010–2012

Since more than 10 years, a consortium of research groups from five Swiss centers have been involved in the development of µSOFC as “small" energy converter device. In November 2012 a successful operation of the complete system was demonstrated at ETH Zurich, see Fig. 1.

The principal part of µSOFC, (as depicted in Fig. 1 part (5) and in Fig. 2), includes electrodes and electrolyte membranes. The challenging contribution of our institute during 2012 was to provide a validated guideline design for the layered membranes system under both manufacturing and operational conditions. In our planar design, thin film YSZ (yttria-stabilisedzirconia) electrolyte layers were fabricated using pulsed laser deposition (PLD). The fabrication is accompanied by large residual compressive stresses that cause the electrolyte to buckle.

This buckling behaviour was investigated based on various experimental methods, analytical estimations, and numerical simulations.

Fig. 1: Demonstration of µSOFC system. Lab on chip: Bieberle-Hutter A. et al. (2012), 4894-4902

Fig. 2: µSOFC: membranes (left), carrier and electrical board (right) in the scale of portable device.

Experimentally, the films have been investigated by wafer curvature, light microscopy, white light interferometry and nano-indentation. The partial release of residual stresses in the film during free etching of the substrate was estimated by a new method combining pre-etching optical measurements with posteriori stress analysis. An energy minimization procedure was subsequently applied in combination with the Rayleigh-Ritz method to determine the various buckling modes, evaluate the buckling amplitudes and determine the threshold values for instability transitions. Comparisons between simulation results and experimental data show excellent agreement and demonstrate the capabilities of this method to predict various buckling stages of free-standing thin films.

Finally, a new post-buckling design space for thin-film electrolyte fabrication has been obtained by applying a stress-based failure criterion, see the following figure.

Fig. 3: The design space for the fabrication of thin YSZ films is shown. The x-axis represents the side length-to-thickness ratios whereas the y-axis represents the residual strain of the film. Under compression, i.e. for negative strains, pre-buckling only exists in a narrow region above the curve of the first buckling. The first and the second post-buckling regions located below the dashed curves c1 and c2 represent zones of high tensile stresses that have to be avoided. However, the post-buckling region also includes large safe zone located above c1 and c2.

Therefore, post-buckling design provides various options for a safe selection of deposition conditions and membrane dimensions.

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Research Report 2012

2.7

Institute of Computational Physics

Belenos Fuel Cell Stack: Simulation and Freezing

Contributors:

J. Schumacher, B. Perucco, G. Sartoris

Partners: Funding: Duration:

PSI, Belenos Clean Power Swiss Federal Office of Energy, Belenos Clean Power 2010â&#x20AC;&#x201C;2014

Introduction Proton exchange membrane (PEM) fuel cells generate electrical power from hydrogen gas and currently undergo intensive research and development. PEM fuel cells are applied for transportation, back-up power, portable power and small distributed generation.

Belenos Clean Power, in cooperation with the Paul Scherrer Institute develops PEM fuel cell systems for passenger vehicles. Certain research aspects become relevant for further development of these fuel cells. In this project we develop coupled (or multiphysics) models to represent the interaction between the transport and reaction processes that are present in an operating PEM fuel cell. Analyzing these interactions by combination of simulation and measurement is essential to identify the energy conversion losses and to improve the fuel cell performance. The Paul Scherrer Institute provides the experimental background for model validation and calibration.

Modeling approaches Transport processes of mass, charge and heat on different length scales of the fuel cell components have to be analyzed to understand and improve the performance of the fuel cell. In the project we focus on two different approaches: 1. We develop a membrane electrode assembly (MEA) model that represents the electrochemical reactions and the transport processes in the through-plane direction of a proton exchange membrane fuel cell. 2. We develop a 2+1D model of a large-area PEM fuel cell.

The 2+1D approach captures the essential features of the coupled transport and reaction processes, and it is suitable to take the high aspect ratio between the in-plane and the throughplane dimensions of fuel cells into account. In the 2+1D model the gas flow-fields of the PEM fuel cell on the anode side and the cathode side are numerically discretized in two dimensions by using a finite element method. This allows to calculate the pressure and velocity distributions in the gas flow-fields. The coupling between two opposing elements of the anode and cathode side is established by the 1D model (see above) representing the MEA. The transport processes for mass and charge and the

electrochemical reactions are accounted for in the model by a nonlinear coupled system of partial differential equations.With the computationally efficient 2+1D model we intend to investigate different large-area fuel cell designs.

Sensitivity analysis In 2012 we performed a sensitivity study of the one-dimensional MEA model. Thereby, we identified the most important model parameters. The investigated model parameters have different influence on the simulation results, i.e. the current drawn from the cell, the average water content or the maximum temperature to be reached in the MEA. The influence of the parameters on the simulation results depend on the operating points on the current voltage curve of the cell.

To determine the sensitivity of a parameter on a specific simulation result, a base case value for all the parameters is defined resulting in a base case simulation for the simulation like the current, for example. The investigated model parameters were varied within a certain range of values. The simulation results with variable parameters were compared to the simulation results obtained for the base case to evaluate the sensitivity.

Validation of the MEA model Quantitative predictions with a fuel cell model can only be achieved if the model is carefully validated. In 2012 we focused on the validation of the electrochemical model description. A small area test fuel cell was used to validated the electrochemical part of the MEA model. The cell voltage was measured as a function of the molar fractions of oxygen and hydrogen, the temperature and the current density.

Flow-field simulations in three dimensions We performed an evaluation study to design different gas distribution flow-fields. A gas flowfield design with parallel channels was investigated and three-dimensional flow-field calculations were performed by solving the incompressible Navier-Stokes equations with a finite element code. In this way we calculated the pressure distribution and the velocity field in the channels. The aim of the study was to achieve a

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homogeneous pressure drop over the gas distribution channels. Different gas inlets and outlet designs were investigated and different gas mixture volume flows were used as boundary conditions at the inlet and outlet. Furthermore, consumption of the reactant gases in the gas distribution channels was modeled. Depending on gas consumption, this requires the gas distribution channels to narrow towards the outlet of the flow-field to achieve a minimum pressure drop.

This is essential to force the water out of the

channels. Some simulation results can be seen in the figure, where the pressure distribution and velocity field of an actual flow-field are plotted.

In the presented case, for example, it can be seen from the pressure distribution plot that the pressure distribution is not homogeneous over a defined cross-section of the gas distribution channels. These 3D gas flow simulations are important to establish reference cases that can be compared to the simplified 2+1D simulation approach.

Simulated three dimensional pressure distribution (left) and velocity field (right) of a straight-channel gas flowfield of a PEM fuel cell. The incompressible Navier-Stokes equations were solved. Boundary conditions for the flow-field at the inlet and the outlet were defined by known volume flow of the gas mixture. We assumed depletion of the gas in the gas distribution channels.

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Research Report 2012

3.1

Institute of Computational Physics

Exploring and Improving Durability of Thin Film Solar Cells

Contributors:

T. Lanz, M. Schmid, C. Kirsch, B. Ruhstaller

Partners:

FP-EMPA, TF-EMPA, LPI-EPFL, PV-Lab-EPFL, CSEM, SUPSI, BASF, AMCOR, Solaronix, Oerlikon Solar, Pramac, Flisom, Fluxim Competence Center Energy and Mobility 2011–2013

Funding: Duration:

The efficiency of thin film solar cells deteriorates with time due to degradation phenomena. The CCEM-CH project DURSOL aims at improving the understanding of the fundamental mechanisms underlying the degradation. ICP’s task within the project is to advance and extend the numerical models of the various solar cell types being investigated.

Fig. 1: Calculated steady-state heating distribution in an amorphous silicon thin-film solar module in the dark for Vapp = −4 V. An artificial shunt was added in the module creating a short circuit between two back contacts.

The performance of thin film solar modules may deteriorate due to the degradation of the electrical conductivity of transparent electrodes caused by water ingress. As the water diffuses into the module from the edges, a spatial representation of the module is required to assess the influence on the module performance. To investigate the kinetics of water ingress and other localized defects, we have developed a finite element method (FEM) model of the electrothermal transport in thin film solar modules. The model uses a computationally efficient 2+1D modeling approach. Using amorphous silicon mini solar modules we have experimentally validated the model using current-voltage measure-

ments under partial shading and lock-in thermography measurements. In Fig. 1 we show the computed local heating rate in the mini module with artificially added shunts. The model thus allows for a quantitative interpretation of the temperature measurements obtained with lock-in thermography. We will use the model to study the performance degradation due to water ingress based on measured diffusion patterns.

In close collaboration with the industrial partner Fluxim AG transient electrical characterization techniques for solar cells have been developed.

The measurement setup is capable of carrying out dark-CELIV, photo-CELIV as well as lightpulse photocurrent responses. The measurements allow for extracting material parameters such as the electron and hole charge mobilities. In Fig. 2 we show dark-CELIV measurements of CIGS solar cells from EMPA. From the observed peak time we can estimate an effective mobility of 0.35 cm2 /Vs, which is in agreement with the expectations for this type of solar cell. We note that the experimental setup is able to resolve the dynamic transport with sub-microsecond resolution, as demonstrated by this high-charge-mobility solar cell.

Fig. 2: Measurements of the transient current response to linearly increasing voltage (CELIV) ramps for various offset voltages for CIGS solar cells.

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Research Report 2012

3.2

Institute of Computational Physics

Simulation of Hydrogen Production with a Photoelectrochemical Solar Cell

Contributors:

P. Cendula, J. Schumacher, M. Schmid

Partners: Funding: Duration:

LPI-EPFL Swiss Federal Office of Energy 2012–2014

Introduction Electrical energy consumption peaks at day and lowers at night. Solar energy production varies between summer and winter and it depends on clouds as well. Therefore, large effort on energy storage solutions is undertaken to balance our energy usage with renewable energy production. Hydrogen is one of the main candidates for such energy storage solutions, because it is an excellent and clean fuel. One obvious solution to renewable hydrogen production is the electrolysis of water with input of renewable electric energy. Another promising alternative to the latter is a photoelectrochemical (PEC) water splitting solar cell, which could be a cheaper single device. A PEC cell absorbs light like a conventional solar cell, but the generated charges are used to drive a water reduction and oxidation reaction in the aqueous electrolyte to produce hydrogen and oxygen, see Fig. 1.

Fig. 1: Photograph of a simple PEC cell for water splitting. Courtesy of the Laboratory of Photonics and Interfaces, EPFL Lausanne.

Motivation The current challenge is to find cheap materials with excellent suitability for PEC cells. Metal oxides such as hematite (iron oxide) and copper oxide have shown certain promise with respect to hydrogen production, but they need to be understood and optimized in order to become economically viable. Numerical simulation is crucial for improved understanding and predicting the behavior of PEC cells and for the characterization of appropriate materials for PEC cells.

Model In collaboration with LPI EPFL, ICP is developing a physical model of the light absorption, energy-band alignment and charge transport in the PEC cell. The optical model is based on forward ray-tracing to simulate the fraction of light that is absorbed, reflected or transmitted through the PEC cell. The electrical model consists of electron and hole continuity equations coupled with Poisson’s equation for the electric potential. The electrical model is numerically solved to calculate the current vs. voltage characteristics or impedance spectra of PEC cells.

Results In 2012, we implemented a software to calculate an energy-band diagram of a PEC cell, see Fig. 2. At this stage, the software plots the energy-bands adopting the analytical solution of the Poisson equation for electric potential. However, we also developed a numerical solution of the Poisson equation, which will be used later in the project. For example, one can deduce the ability of hematite to oxidize water because its quasi-Fermi energy of holes EF∗ p is below the water oxidation potential Eox . By varying the material parameters like bandgap energy, diffusion length of holes etc., their effect on the ability to oxidize water can be understood. Since the PEC cell community often refers to the energyband diagram only with qualitative argumentation, our energy-band diagram improves the understanding of PEC cells for various materials and resolves some inconsistencies found in the PEC literature.

For the optical model, optical reflections were measured at EPFL for standalone Quartz and Glass-FTO and also for a complete PEC cell with hematite. Currently, we are collecting material data for the spectral refractive index and the extinction coefficient of the individual layers, which will enable analysis of optical losses in the individual layers.

Outlook Currently, we are working on an extension of the electrical model to account for the surface states in the semiconductor and a transient numerical model to simulate ac impedance spectra. Furthermore, we are developing an optical model to simulate the reflection and the absorption of light. The simulation results are compared with measurements of PEC cells that are performed at EPFL.

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Fig. 2: Snapshot of the energy-band diagram of a PEC cell with n-type hematite (implemented in Mathematica). Material parameters can be interactively changed to see their effect on the energy-band positions.

The common scale of electrochemical energy is used : the left axis shows an energy with respect to the normal hydrogen electrode (NHE) and the right axis with respect to the reference hydrogen electrode (RHE).

Conduction and valence band edges of the semiconductor separated from electrolyte, ECB and EV B , are shown as dashed lines. Upon contacting the semiconductor with electrolyte, a space charge region is formed in the semiconductor which causes the bending of band edges (shown as solid lines). An applied bias potential Va further increases the band bending in the semiconductor and shifts the semiconductor Fermi level EF n = EF p down. Upon illumination, the concentration of photogenerated holes dramatically increases as reflected in their quasi-Fermi level EFâ&#x2C6;&#x2014; p . Electrochemical potentials for oxidation and reduction of water are denoted Eox and Ered , respectively. The Fermi level in the metal EF,metal is automatically adjusted by potentiostat to enable hydrogen evolution at the metal (with certain overpotential above Ered ).

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3.3

Institute of Computational Physics

Integration of High Temperature Electric Converter for Electricity Generation in a Solide Oxide Fuel System

Contributors:

M. Schmid

Partners: Funding: Duration:

SSC-EMPA, LPCM-EPFL, ITP-ETHZ, CRISMAT-CNRS (Fr), Hexis AG Competence Center Energy and Mobility, Swiss Federal Office of Energy 2012–2016

Solide oxide fuel cells (SOFCs) convert chemical energy stored in a fuel (hydrogen or natural gas) to electricity. The combustion of the fuel in the SOFC leads to waste heat of temperatures up to 900 ◦ C. When the SOFC system is integrated in buildings, the waste heat is usually used for hot water production. However, using thermoelectric converters (TECs) a part of the waste heat may be converted to additional electricity, which is the most valuable form of energy.

The goal of this project is to develop a thermoelectric converter for the implementation into the SOFC system of Hexis AG. Thermoelectric converters consist of thermoelectric legs made of two different semiconductor materials (see Figure 2). The legs are connected electrically in series and thermally in parallel. If a temperature gradient is applied along the legs an electrical potential difference between the hot and the cold side is formed. The potential difference is due to the so called Seebeck effect. The potential difference leads to an electrical current flowing through the thermoelectric legs. The working principle of a TEC containing a single thermoelectric couple is illustrated in Figure 1.

Fig. 1: Working principle of a TEC built with two thermoelectric legs.

Low temperature TECs are already available on the market. These TECs are attached to hot parts of motors or stoves. However, for higher temperatures above about 300 ◦ C the appropriate materials still have to be developed.

Fig. 2: Thermoelectric Converter. Image Courtesy: EMPA

These materials not only have to resist the higher temperatures, they also have to combine some competing physical properties: high electrical conductivity and thermolectric effect, but at the same time high thermal resistivity. Ideal candidate materials include perowskite-like metal oxides. These candidate materials are developed and investigated at SSC-EMPA in order to construct high temperature TECs to temperatures up to 900 ◦ C. The work task of the ICP in this project is to develop a physical model for these high temperature TECs. The model is used to simulate temperature, electric potential, current and heat flow density distribution inside the TECs. In Figure 3, we show the electric potential distribution inside the two TEC legs along the central line.

Fig. 3: Electric potential inside the TEC legs along the central line (black and blue lines are for the ntype and p-type leg respectively). The temperature dependence of the material properties is taken into account.

The simulations allow to derive guidelines for the optimal design of the TEC modules and to quantify the different energy conversion losses.

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3.4

Institute of Computational Physics

Thermofluiddynamische Modellierung von Biomassevergasung

Contributors:

G. Boiger, T. Hocker, C. Meier

Partners: Funding: Duration:

Keine Gebert Rüf Stiftung 2009–2013

Die Vergasung von Biomasse wie zum Beispiel Holz bietet die Möglichkeit, einen stückförmigen, festen Energieträger in eine Gasphase mit hoher Energiedichte und Homogenität umzuwandeln. Dieses Konzept hat bedeutende technische Relevanz und gilt als Verfahren mit Potential.

Mit heutigem Stand der Technik fällt es nach wie vor schwer grosse Biomassevergasungsanlagen mit ausreichender Rentabilität zu betreiben. Einer der Hauptgründe dafür ist die hohe Wartungsintensität derartiger Aggregate. Dies ist unter anderem darauf zurückzuführen, dass kaum flexible und konsistente Konzepte zur dynamischen Anpassung der wichtigsten Anlageparameter an variierende Brennstoffqualitäten existieren. Zur effizienten Anlagenbetreuung benötigt der Betreiber eine Steuerung, oder zumindest einen Leitfaden, welcher die wichtigsten Regelgrössen des Vergasungsprozesses (wie z.B.: Prozessluftzufuhr, Produktgasrückführung, Prozessluftvorwärmung) an die Eigenheiten des momentan zugeführten Rohstoffes (wie Porosität der Schüttung, Permeabilität, Heizwert, Feuchtegehalt) anpasst. Thermofluiddynamische Modellierung des Vergasungsprozesses kann einen derartigen Zusammenhang herstellen und somit dazu dienen Regeln für die Steuerung von Anlagen beliebiger Größe abzuleiten.

Am ICP wird zunächst an einem möglichst kompakten, ein-dimensionalen, thermofluiddynamischen Modell des Vergasungsprozesses gearbeitet. Dieser Ansatz soll sich auf eine vereinfachende, aber grundlegende, analytische Aufarbeitung des gekoppelten Multiphysikproblems des Vergasungsprozesses stützen. Dabei sollen bereits viele, physikalisch relevante Teilbereiche der Vergasung eines vereinfachten Biomassepartikels miteinbezogen werden. Es sind dies: Die Zufuhr der Prozessluft in die Biomasseschüttung; Der Stofftransport des Sauerstoffes

an die Reaktionszone des einzelnen Biomassepartikels; Die Umwandlung der Prozessluft in ein Gemisch aus Luft und Produktgas; Der konvektiv – diffusive Entropieaustausch zwischen Partikel und Produktgas – Luft Gemisch; Die thermisch getriebene Pyrolyse der Biomasse; Die thermodynamisch und stöchiometrisch bestimmte, als Vergasung bezeichnete, Reaktion der Edukte zu Kohlenmonoxid, Wasserstoff, Kohlendioxid, Methan, Wasserdampf und Sauerstoff, aber auch Kohle und teerigen Rückständen; Die Einstellung eines thermodynamischen Gleichgewichtes des Produktgases in Abhängigkeit der vorherrschenden Temperatur; Die Ermittlung der Energiebilanz sowie der Reaktionsenthalpie der Partikelmaterie, sowie die Weitergabe abströmender Materie und Entropie an darauffolgende Partikelberechnungszellen.

Dieses ein-dimensionale Vergasungsmodell soll möglichst modular aufgebaut sein, um durch diverse Untermodelle (z.B. zur detaillierten Beschreibung der Partikeltemperaturverteilung bzw. dem Abdampfverhalten der Partikelfeuchtigkeit) ausgebaut werden zu können.

Das ein-dimensionale Schema soll also ein theoretisches Fundament für die Ausweitung der Betrachtung auf ein vollständiges, dreidimensionales Schüttgutmodell liefern. Ein, auf der „open source CFD toolbox“, OpenFOAM basierendes, vollständig drei-dimensionales, thermofluiddynamisches Modell soll im weiteren Projektverlauf das ein-dimensionale Modell ablösen und ergänzen. Durch das Heranziehen detaillierter, la’grangscher Methodik zur Beschreibung der drei-dimensionalen Schüttguteigenschaften soll es gelingen die Variationen zwischen verschiedenen Rohstoffqualitäten hochauflösend darzustellen. Damit bestünde die Möglichkeit, einen deutlichen Fortschritt zu den bisherigen Möglichkeiten der Vergasungsmodellierung zu erzielen.

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Research Report 2012

4.1

Institute of Computational Physics

Light Outcoupling from Organic Light-Emitting Diodes

Contributors:

C. Kirsch, R. Knaack, K. Lapagna, K. Pernstich, B. Ruhstaller

Partners: Funding: Duration:

Glas Trösch AG, Fluxim AG CTI 2012–2014

Solid state lighting is an interesting field of application for organic light-emitting diodes (OLEDs), in addition to their more prominent use in digital displays of mobile phones or televisions. Largearea flat panel lights with homogeneous luminance can be produced using OLEDs. White OLEDs are of particular interest in generalpurpose lighting applications, as they can produce warm white light that is more pleasing to the human eye than the light from fluorescent light sources. Because of the organic materials used, OLEDs are easier to dispose of than fluorescent lamps, which contain phosphor and mercury.

The luminous efficacy is an important quantity for judging the energy efficiency of light sources: it is the ratio between the total luminous flux emitted by the device and the total amount of input power it consumes. Current white OLED devices have a luminous efficacy similar to fluorescent lamps and are catching up with (inorganic) LEDs. The organic materials used in OLED devices have a refractive index of n1 ' 1.7, and the light emitted from the device needs to propagate into air with refractive index n2 ' 1 in a typical lighting application. The contrast in refractive indices causes total internal reflection of light beyond the critical incidence angle θc (Fig. 1), which considerably reduces the luminous flux from an OLED device and thus its energy efficiency. Techniques for light outcoupling improvement include scattering foils and other high-index scattering layers.

In this project we are interested in the design of light outcoupling layers which can be coated on the large-area float glass produced by Glas Trösch AG, and then be marketed to OLED manufacturers. At another research institute, techniques are developed to produce those layers, and both partners rely on the simulation results obtained by the ICP to assess the usefulness of various light outcoupling strategies.

Both geometrical optics and wave optics methods are applied in this project to simulate the propagation of light from the OLED through the light outcoupling layer and the glass substrate into air: Mie scattering theory is used in a commercial raytracing software, and scalar scattering theory is used in the OLED and solar cell

simulation software Setfos by Fluxim AG. Here we focus on wave optics.

Fig. 1: Total internal reflection for incidence angles larger than the critical angle θc = arcsin(n2 /n1 ).

Our simulation approach is based on rigorous coupled wave analysis (RCWA). This is a Fourier-space method for solving Maxwell’s equations in the frequency domain, and it can be used to simulate the propagation of light in media with feature sizes on the order of the wavelength of light. RCWA does not involve any geometrical optics approximation and therefore diffraction and interference are naturally accounted for. Moreover, being a semi-analytical method it can be much more computationally efficient than mesh-based methods.

The reflection and transmission properties of light outcoupling layers for white OLEDs must be non-dispersive, because otherwise the color of the light emitted from the device would depend on the viewing angle. Simulations need to be carried out over a range of wavelengths in order to verify this property for a given microstructure. With our RCWA simulation we were able to shed light on the dispersion issue and we now have a better idea of the kind of microstructures that can be expected to be non-dispersive.

Simultaneously, prototype OLED devices are produced and experimental investigations of various light outcoupling strategies conducted at ICP’s own optoelectronic research laboratory.

These experimental results are also used to validate the simulations.

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Research Report 2012

4.2

Institute of Computational Physics

From Atoms to Large-Area OLEDs -the IM3OLED Project

Contributors:

E. Knapp, K. Lapagna, B. Ruhstaller

Partners:

Holst Centre (Nl), Philips (Nl), Fluxim AG, Moscow Engineering Physics Institute (Ru), Kintech Lab (Ru), Photochemistry Center of the Russian Academy of Sciences (Ru) EU-FP7 2011â&#x20AC;&#x201C;2014

Funding: Duration:

OLED technology provides an environmentally friendly technology that requires no mercury and can potentially enable energy savings up to 90 % (per lamp socket). Global transition to such efficient lighting sources would dramatically reduce the energy consumption. Since the onset of the solid state lighting initiative towards the end of the last century, the advance in OLED technology has been accelerated by a world-wide investment in material science, process technology, and infrastructure. The technological hurdles are still challenging and numerous, and the target efficiency, colour, colour rendering and lifetime has only partly been accomplished.

To tackle these issues the IM3OLED project (Integrated Multidisciplinary and Multiscale Modeling for Organic Light-Emitting Diodes) started in 2011. It is funded by the EU and is a collaboration between Russia and Europe. The overall goal of the IM3OLED project is the development, evaluation and validation of a predictive multi-scale and multi-disciplinary modelling tool that will accelerate research and development of organic light-emitting diodes for lighting applications. In Fig. 1 shows the tool chain from the molecular level up to the 3D OLED, where simulations and experiments on different length scales are performed. The focus of the ICP is on the development and refinement of the continuum drift-diffusion model for organic semiconductors as well as on the electro-thermal largearea OLED model.

Fig. 1.: Simulation chain from the atom up to the 3D

device. The ICP develops electrical simulations as well as 3D large-area OLEDs.

The ICP has developed an efficient large-area OLED model based on a finite element approach. The results are shown in Fig. 2, where the brightness of two OLEDs is compared. Due to the low conductivity of the transparent anode, a potential drop over the device takes place resulting in a reduced brightness as displayed on the left. On the right, an improved OLED with a metal grid structure to enhance the conductivity of the anode is shown.

reference OLED

OLED with metal grid

Fig. 2.: Brightness distribution for a reference OLED and an OLED with enhanced anode conductivity due to a metal grid structure.

Further improvements can be achieved in the light outcoupling of an OLED by introducing layers that contain microstructures such as scatter particles or micro lenses, which support the extraction of waveguided and plasmonic modes into the substrate and also contribute to the extraction from the substrate into air. These layers can be partially modelled by means of geometrical optics. Therefore, the ICP has developed, in close collaboration with Fluxim, a model that combines the benefits of a semi-analytical description of dipole emission into such layers with 3D ray tracing capabilities.

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4.3

Institute of Computational Physics

Erweiterung der Laborinfrastruktur zur Herstellung von Organischen Leuchtdioden am ICP

Contributors:

K. Pernstich, B. Ruhstaller, T. Beierlein

Partners: Funding: Duration:

keine SoE-ZHAW fortlaufend

Am ICP wird seit ca. 10 Jahren Forschung auf dem Gebiet der organischen Elektronik auf nationaler und internationaler Ebene betrieben, bisher ausschliesslich mit Modellbildung, Simulation und Messtechnik. Das ICP hat dieses Jahr seine Laborinfrastruktur um eine Beschichtungsanlage für kohlenstoffbasierte Halbleiter erweitert. Diese Anlage bietet insbesondere die Möglichkeit, organische Leuchtdioden (OLEDs), aber auch organische Solarzellen und andere elektronische Bauteile auf Polymer-Basis herzustellen.

Organische Leuchtdioden werden bereits in Displays kommerziell eingesetzt, z.B. im Smartphone Galaxy S3 von Samsung. Der Einsatz von OLEDs als grossflächige Beleuchtungselemente ist ebenfalls sehr vielversprechend. Solch grossflächige OLEDs benötigen keinen Lampenschirm wie konventionelle Leuchtmittel, sie sind sozusagen der Lampenschirm. Dadurch eröffnen sich ganz neue Einsatzmöglichkeiten, z.B. in der Architektur als transparente OLEDs integriert in eine Fensterscheibe, als Hintergrundbeleuchtung für Flüssigkristallanzeigen, oder als Stilelement in Raumgestaltungen. OLEDs haben zudem im Labormassstab bereits eine höhere Effizienz als konventionelle Leuchtstofflampen bewiesen

und können so einen Beitrag zur Energieeffizienz liefern.

Die neu angeschaffte Beschichtungsanlage besteht aus einer mit Stickstoff gefüllten Handschuhbox mit angeschlossener Vakuumkammer. In der Handschuhbox werden die Polymerfilme unter Ausschluss von Wasserdampf und Sauerstoff hergestellt, und in der Vakuumkammer werden die benötigten Metallelektroden aufgedampft. Die elektrischen und optischen Eigenschaften der so hergestellten Proben können nun messtechnisch untersucht werden und dienen als Grundlage zur Verifikation und Erweiterung von numerischen Modellen.

Die Möglichkeiten, die diese Beschichtungsanlage eröffnet, sind wichtig für Projekte mit Industriepartnern, in denen die durchgeführten Simulationen nun auch experimentell überprüft und dadurch auch verfeinert werden können. Ein erstes KTI-Projekt, in dem die Anlage zum Einsatz kam, ist auf Seite 30 beschrieben. Des weiteren bietet die Anlage die Möglichkeit, zahlreiche studentische Arbeiten durchzuführen. Diese Arbeiten sind trotz ihres Praxisbezugs relativ nahe an der Grundlagenforschung und daher insbesondere für Studierende in Masterstudiengängen interessant.

Fotographie der neuen Beschichtungsanlage am ICP (links) und OLED Demonstrator der Firma Novaled (rechts).

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Appendix A.1

Student Projects

D. B ENZ , N. H ÄNI, ICE-LED Video Multi-Cluster mit Redundanz, Betreuer: N. Reinke, A. Bariska, Bachelorarbeit.

B. B IGLER , F. M ATHYS, Early-stage skin cancer detection with active thermography, Betreuer: M. Bonmarin, N. Reinke, A. Bariska, Bachelor Thesis.

B. B IGLER , F. M ATHYS, Measurement System for Early Stage Skin Cancer Detection, Betreuer: N. Reinke, A. Bariska, Bachelorarbeit.

L. B RENNER , T. H UNKELER, Erstarrung von Schokolade im Kühlkanal, Betreuer: T. Hocker, O. Hoenecke, Firmenpartner: Max Felchlin AG, Schwyz, 2012, Projektarbeit Maschinentechnik, Bachelor of Science.

P. FAHRNI , Y. W ERNER, Thermische Analyse von Schoggi im Kühlkanal, Betreuer: T. Hocker, Firmenpartner: Max Felchlin AG, Schwyz, 2012, Bachelor Thesis Systemtechnik, Bachelor of Science.

D. G ÜRTLER, Nachhaltigkeit der Brennstoffzellentechnologie in der Mini-Kraft-Wärmekoppelung, Betreuer: T. Hocker, H. Spiess, Firmenpartner: Hexis AG, Winterthur, 2012, Projektarbeit Maschinentechnik, Bachelor of Science.

L. K AUFMANN, Thermo-mechanisches Verhalten von Hochtemperatur-Brennstoffzellen, Betreuer: T. Hocker, Firmenpartner: Hexis AG, Winterthur, 2012, Vertiefungsarbeit Master of Science.

P. L ENHERR , D. W ILD, Thermogradientenprüfstand für Brennstoffzellen, Betreuer: L. Kaufmann, T. Hocker, Firmenpartner: Hexis AG, Winterthur, 2012, Bachelor Thesis Maschinentechnik, Bachelor of Science.

D. M INDER , S. O BRADOVIC, Erstarrung von Schokolade im Labor, Betreuer: T. Hocker, O. Hoenecke, Firmenpartner: Max Felchlin AG, Schwyz, 2012, Projektarbeit Maschinentechnik, Bachelor of Science.

D. S CHMIDBAUER , M. TORRONI, Bilderkennung in Thermografie-Bildern, Betreuer: N. Reinke, A. Bariska, Bachelorarbeit.

A. S IBILIA, Konstruktion und Herstellung eines Probenhalters für Vakuumbeschichtungen, Betreuer: K.P. Pernstich, B. Ruhstaller, Vertiefungsarbeit Master of Science.

M. S UTER, Modeling the Shukoff Cooling Curve of Oils, Betreuer: T. Hocker, Firmenpartner: Max Felchlin AG, Schwyz, 2012, Vertiefungsarbeit Master of Science.

E. T INNER , R. A NGEHRN, Zerstörungsfreie und berührungslose Prüfung von Verbundmaterialien, Betreuer: N. Reinke, A. Bariska, Bachelorarbeit.

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M. W ERNER , M. W YSS, Skin cancer detection with active thermography, Betreuer: M. Bonmarin, N. Reinke, A. Bariska, Firmenpartner: Winterthur Instruments AG, Winterthur, Bachelor Thesis.

P. W ETTER , A. K ÜNZLER |, Bildgebendes Analyseverfahren für Feuchtigkeit in Bauwerken, Betreuer: N. Reinke, A. Bariska, Bachelorarbeit.

A.2

Scientific Publications

M. B ONMARIN , N. R EINKE , A. FASTRICH, Vorrichtung und Verfahren zur Charakterisierung von Gewebe, Patent CH, Application Nr. 01684/12, Submitted.

D. B URNAT, A. H EEL , L. H OLZER , D. K ATA , J. L IS , T. G RAULE, Synthesis and Performance of A-Site Deficient Lanthanum-Doped Strontium Titanate by Nanoparticle Based Spray Pyrolysis, J. Power Sources, 201, 26–36, 2012.

D. B URNAT, A. H EEL , L. H OLZER , E.H. OTAL , D. K ATA , T. G RAULE, On the chemical interaction of nanoscale lanthanum doped strontium titanates with common scandium and yttrium stabilized electrolyte materials, Int. J. Hydrogen Energy, 37, 18326–18341, 2012.

A. E VANS , M. P RESTAT, R. TÖLKE , M. V. F. S CHLUPP, L. J. G AUCKLER , Y. S AFA , T. H OCKER , J. C OURBAT, D. B RIAND, N. F. DE R OOIJ, D. C OURTY, Residual Stress and Buckling Patterns of Free-standing Yttria-stabilized-zirconia Membranes Fabricatedby Pulsed Laser Deposition, Fuel Cells, 12, 614–623, 2012.

I. G RUBER , I. Z INOVIK , L. H OLZER , A. F LISCH , L. P OULIKAKOS, A computational study of the effect of structural anisotropy of porous asphalt on hydraulic conductivity, Construction and Building Materials 96, 66–77, 2012.

B. I WANSCHITZ , L. H OLZER , A. M AI , M. S CHÜTZE, Nickel agglomeration in solid oxide fuel cells: the influence of temperature, Solid State Ionics, 211, 69–73, 2012.

E. K NAPP, B. RUHSTALLER, The role of shallow traps in dynamic characterization of organic semiconductor devices , J. Appl. Phys. 112, 024519, 2012.

T. L ANZ , L. FANG , S.J. B AIK , K.S. L IM , B. RUHSTALLER, Photocurrent increase in amorphous Si solar cells by increased reflectivity of LiF/Al electrodes, Solar Energy Materials and Solar Cells 107, 25, 2012.

C H . M EIER , T. H OCKER , A. B IEBERLE -H ÜTTER , L. J. G AUCKLER, Analyzing a micro-solid oxide fuel cell system by global energy balances, Int. J. Hydrogen Energy, 37 (13), 10318–10327, 2012.

A. N AKAJO, J. K UEBLER , A. FAES , U. VOGT, H. S CHINDLER , L. C HIANG , S. M ODENA , J. VAN HER LE , T. H OCKER , Compilation of mechanical properties for the structural analysis of solid oxide fuel cell stacks. Constitutive materials of anode-supported cells, Ceramics International, 38, 3907– 3927, 2012.

M.T. N EUKOM , S. Z ÜFLE , B. RUHSTALLER, Reliable extraction of organic solar cell parameters by combining steady-state and transient techniques, Organic Electronics 13, 2012.

B. P ERUCCO, N.A. R EINKE , D. R EZZONICO, E. K NAPP, S. H ARKEMA , B. RUHSTALLER, On the exciton profile in OLEDs-seamless optical and electrical modeling, Organic Electronics 13, 2012.

N. R EINKE, Pulverschichtdicken dank innovativer Autokalibration präzise messen, Besser lackieren, Juli 2012.

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N. R EINKE, Feuchte Lacke auf Kunststoff messen, JOT Journal für Oberflächentechnik, Juni 2012.

J.O. S CHUMACHER , J. E LLER , G. S ARTORIS , B. S EYFANG , T. C OLINART, A 2+1D model of a proton exchange membrane fuel cell with glassy-carbon micro-structures, Mathematical and Computer Modelling of Dynamical Systems, 1–23, 2012.

D. W IEDENMANN , L. K ELLER , L. H OLZER , J. S TOJADINOVIC, B. M ÜNCH , L. S UAREZ , B. F UMEY, H. H AGENDORFER , R. B RÖNNIMANN , P. M ODREGGER , M. G ORBAR , U. VOGT, A. Z ÜTTEL , F. L A M ANTIA , R. W EPF, B. G ROBÉTY, 3D pore structure and ion conductivity of porous ceramic diaphragms, AIChE Journal, in press, 2012.

A.3

Book Chapters

L. H OLZER , M. C ANTONI, Nanofabrication using focused ion and electron beams: Principles and applications, Book Chapter, Review of FIB-tomography / I. Utke, S.A. Moshkalev, Ph. Russell (Ed.) - Oxford University Press, NY, USA, ISBN 9780199734214, 410–435, 2012.

A.4

News Articles

EMPA, Turbo für die Brennstoffzelle, Seite 27, c’t 2/2013.

N. W EIBEL, ZHAW entwickelt Computermodelle – lang lebe die Brennstoffzelle, Unternehmer Zeitung.

A.5

Exhibitions

M. Bonmarin, Lock-In Thermography, World Medtech Forum, Lucerne, 2012.

M. Prestat et al. Miniaturized free-standing SOFC membranes on silicon chips. In: 10th EUROPEAN SOFC FORUM, Lucerne, 2012.

A.6

Conferences and Workshops

S. B AIK , M. N EUKOM , L. FANG , K. L IM , T. VAN DER H OFSTAD, T. L ANZ , B. RUHSTALLER, Fast and direct characterization of thin film Si solar cells using CELIV, 27th European Photovoltaic Solar Energy Conference and Exhibition, Frankfurt, Germany, 2012.

P. C ENDULA , M. S CHMID, J. O. S CHUMACHER, Development of a comprehensive numerical model of a solar water splitting cell, International Conference on Nanostructured Systems for Solar Fuel Production, Mallorca, Spain, 2012.

A. E VANS ET AL ., Residual stress and buckling patterns of yttria-stabilisedzirconia thin films for micro-solid oxide fuel cell membranes, The Electrochemical Society, 221st ECS Meeting, Washington, USA, 2012.

L. H OLZER , M. C ANTONI , P H . G ASSER , B. M ÜNCH , L. K ELLER, FIB-tomography: Review and discussion of applications in materials science, Interdisciplinary symposium on 3D-microscopy,

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SSOM, Les Diablerets, 2012.

L. H OLZER , T H . H OCKER , L. K ELLER , M. P RESTAT ET AL ., Quantitative tomography for the prediction of transport kinetics in SOFC electrodes and in porous diaphragms for electroysis cells, E-MRS Spring Meeting, Strasbourg, France, 2012.

B. I WANSCHITZ , L. H OLZER , A. M AI , M. S CHÜTZE, Nickel agglomeration in solid Oxide Fuel Cells under different operating conditions, 10th European Fuel Cell Forum EFCF, A1001, Lucerne, 2012.

B. I WANSCHITZ , L. H OLZER , A. M AI , M. S CHÜTZE, Nickel agglomeration in solid Oxide Fuel Cells under different operating conditions, Jahrestreffen Fachgruppen Energieverfahrenstechnik und Hochtemperaturtechnik, DECHEMA, Frankfurt, Germany, 2012.

Y. J AMASHITA , B. RUHSTALLER, Advanced Characterization of Solar Cells, Swiss Green Technologies Seminar, Tokyo, Japan, 2012.

L. K ELLER , L. H OLZER, Imaging methods and its use in characterizing the pore space of Opalinus Clay in 3D, Int. Clay Conference, Montpelier, France, 2012.

E. K NAPP, The Role of Shallow Traps in Dynamic Characterization of Organic Semiconductor Devices, SIMOEP 12, Olvia, Spain, 2012.

T. L ANZ , C. B ATTAGLIA , C. B ALLIF, B. RUHSTALLER, Model-based Quantitative Assessment of Crystallinity and Parasitic Absorption in Microcrystalline Silicon Solar Cells, Spring MRS, San Francisco, USA, 2012.

M. N EUMANN , G. G AISELMANN , A. S PETTL , L. H OLZER , T. H OCKER , M. P RESTAT, V. S CHMIDT, Structural Segmentation and Stochastic 3D modeling of La0.6Sr0.4CoO3-d - cathodes, 9th Symposium on Fuel Cell and Battery Modeling and Experimental Validation Modval, Sursee, 2012.

O. P ECHO, L. H OLZER , Z. YANG , T H . H OCKER , R. F LATT, J. M ARTINZUK , L. G AUCKLER , M. P RE STAT , Quantitative microstructure analysis and electrochemical activity of La0.6Sr0.4CoO3-d electrodes deposited by spray pyrolysis, Materials Research Fall Meeting MRS, Boston, USA, 2012.

O. P ECHO, M. P RESTAT, Z. YANG , J.H. H WANG , J.W. S ON , L. H OLZER , T. H OCKER , J. M AR TYNCZUK , L. G AUCKLER , Microstructural and electrochemical characterization of thin La0.6Sr0.4CoO3-d cathodes deposited by spray pyrolysis, 10th European Fuel Cell Forum EFCF, B04-61, Lucerne, 2012.

O. P ECHO, M. P RESTAT, Z. YÁNG , L. H OLZER , T. H OCKER , J. M ARTYNCZUK , L. G AUCKLER, Quantitative microstructure analysis and electrochemical activity of La0.6Sr0.4CoO3-d electrodes deposited by spray pyrolysis, CFN Summer School on Nano-Energy, Poster, Bad Herrenalb, Germany, 2012.

M. P RESTAT, A. E VANS , R. TÖLKE , M.V.F. S CHLUPP, B. S CHERRER , Z. YANG , J. M ARTYNCZUK , O. P ECHO, H. M A , A. B IEBERLE -H UTTER , L. G AUCKLER , Y. S AFA , T. H OCKER , L. H OLZER , P. M URALT, Y. YAN , J. C OURBAT, D. B RIAND, N.F. DE R OOIJ, Miniaturized free-standing SOFC membranes on silicon chips, 10th European Fuel Cell Forum EFCF, A07-30, Lucerne, 2012.

M. P RESTAT, L. H OLZER , T. H OCKER , O. P ECHO, ET AL ., Miniaturized solid oxide fuel cells on a chip, 9th Symposium on Fuel Cell and Battery Modeling and Experimental Validation Modval, Sursee, 2012.

M. P RESTAT, Z. YÁNG , O. P ECHO, L. H OLZER , J. M ARTYNCZUK , A. E VANS , L. G AUCKLER , T. H OCKER , J. H WANG , J. S ON, Nanostructured La0.6Sr0.4CoO3-d Cathodes Prepared by Spray Pyrolysis for Thin Film SOFC, Pacific Rim Meeting on electrochem. and solid-state science / 222nd

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meeting of ECS, PRIME2012, Honolulu, USA, 2012.

N. R EINKE, Thermische Schichtprüfung, Zentralschweizer Photonenmesstag - floir ag, GisikonRoot, 2012.

N. R EINKE, Berührungslose Prüfung von Materialien und Oberflächen, Thüringer Grenz- und Oberflächentag, Leipzig, Germany, 2012.

N. R EINKE, Berührungslose Prüfung von Materialien und Oberflächen, Winterthurer Oberflächentag, Winterthur, 2012.

N. R EINKE, Feuchte Lacke auf Kunststoff messen, Fachtagung Oberflächentechnik, KunststoffInstitut Lüdenscheid, Germany, 2012.

N. R EINKE, Bildgebende Analyseverfahren für Mauerwerk, Tagung Einblick in Beton, Irscat AG, Oberdorf, 2012.

B. RUHSTALLER, Advanced simulation of OLEDs and organic solar cells, Keynote Lecture at the Winter School of Organic Electronics, Universität Heidelberg, Heidelberg, Germany, 2012.

B. RUHSTALLER, Charge Transport and Light Propagation in Organic Semiconductor Devices, Intl.

Conference on Simulation of Organic Electronics and Photovoltaics (SIMOEP), Oliva, Spain, 2012.

B. RUHSTALLER, Charge Transport and Light Propagation Modeling in Organic Semiconductor Devices, Jahrestagung der Schweizerischen Physikalischen Gesellschaft (SPG), Zürich, 2012.

Y. S AFA ET AL ., A Validated Model of Membrane Mechanics for Micro SOFC, 9th Symposium on Fuel Cell and Battery Modelling and Experimental Validation, PSI Paul Scherrer Institut, 2012.

J.A. S CHULER , B. I WANSCHITZ , L. H OLZER , M. C ANTONI , T H . G RAULE, Stroboscopic Ni Growth/Volatilization Picture, 10th European Fuel Cell Forum EFCF, B0501, Lucerne, 2012.

J.O. S CHUMACHER , B. P ERUCCO, F ELIX N. B ÜCHI , J. R OTH, Sensitivity analysis and investigation of parameter interactions of a model of the membrane electrode assembly of a PEM fuel cell, 9th Symposium on Fuel Cell and Battery Modeling and Experimental Validation, Campus Sursee, 2012.

A.7

Prizes and Awards

E. Tinner and R. Angehrn received the Axa Innovationspreis for their Bachelor Thesis Zerstörungsfreie und berührungslose Prüfung von Verbundmaterialien.

N. Reinke and A. Bariska received the 2nd Rank Prix Strategis Award for their Spin-Off Company Winterthur Instruments AG. N. Reinke and A. Bariska received the 2nd Rank Swisspark Start-up of the year for their Spin-Off Company Winterthur Instruments AG. N. Reinke and A. Bariska received the besser lackieren! Produkthighlight Award for their Spin-Off Company Winterthur Instruments AG. N. Reinke and A. Bariska received the Heuberger Jungunternehmerpreis for their Spin-Off Company Winterthur Instruments AG.

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N. Reinke and A. Bariska received the Swiss Top 100 Entrepreneurs Award for their Spin-Off Company Winterthur Instruments AG. P. Fahrni and Y. Werner received the 3. Price in Life Sciences of the Veronika und Hugo Bohny Stiftung und Toolpoint Cluster for their Bachelor Thesis Thermische Analyse von Schoggi im Kühlkanal.

P. Wetter and A. Künzler received the Siemens Excellence Award for their Bachelor Thesis Bildgebendes Analyseverfahren für Feuchtigkeit in Bauwerken.

A.8

Teaching

M. B ONMARIN, Physik für Ingenieure 1, Bachelor of Science.

J.O. S CHUMACHER, Physik für Ingenieure 1, Bachelor of Science.

N. R EINKE, Physik für Ingenieure 1, Bachelor of Science.

N. R EINKE, Physik für Maschinentechnik 2, Bachelor of Science.

J.O. S CHUMACHER, Physik für Maschinentechnik 2, Bachelor of Science.

N. R EINKE, Physik für Systemtechnik 2, Bachelor of Science.

T. H OCKER, Physik und Systemwissenschaft für Aviatik 1, Bachelor of Science.

T. H OCKER, Fluid- und Thermodynamik 1, Bachelor of Science.

T. H OCKER, Fluid- und Thermodynamik 3, Bachelor of Science.

B. RUHSTALLER, Grundlagen der Solartechnik, Bachelor of Science.

B. RUHSTALLER, Messtechnik in Solarsystemen, Bachelor of Science.

T. H OCKER, Mensch–Technik–Umwelt, Bachelor of Science.

N. R EINKE, Sensorik Praktikum, Bachelor of Science.

R. A XTHELM, Mathematik für Ingenieure 1, Bachelor of Science.

R. A XTHELM, Mathematik für Ingenieure 2, Bachelor of Science.

R. A XTHELM, Mathematik: lineare Algebra für Ingenieure 1, Bachelor of Science.

M. S CHMID, Mathematik: lineare Algebra für Ingenieure 1, Bachelor of Science.

R. A XTHELM, Mathematik: lineare Algebra für Ingenieure 2, Bachelor of Science.

M. S CHMID, Mathematik: lineare Algebra für Ingenieure 2, Bachelor of Science.

C. K IRSCH, Natur, Technik und Systeme 1 – Praktikum, Bachelor of Science.

T. H OCKER, Heat and mass transfer with two-phase flow, Master of Science.

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J.O. S CHUMACHER, Advanced Thermodynamics, Master of Science in Engineering.

J.O. S CHUMACHER, Multiphysics Modelling and Simulation, Master of Science in Engineering.

J.O. S CHUMACHER, Mathematical Methods, Master Online Photovoltaics, Germany.

J.O. S CHUMACHER, Numerical Simulation of Solar Cells, Master Online Photovoltaics, Germany.

G. S ARTORIS, Masterprogram Micro- and Nanotechnology MNT, Weiterbildung.

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A.9

Institute of Computational Physics

ICP-Team

Name

Function

e-Mail

Dr. Rebekka Axthelm Dr. Gernot Boiger Dr. Mathias Bonmarin Dr. Peter Cendula Samuel Hauri Prof. Dr. Thomas Hocker Dr. Lorenz Holzer Lukas Kaufmann Dr. Lukas Keller Dr. Christoph Kirsch Evelyne Knapp Thomas Lanz Kevin Lapagna Markus Linder Christoph Meier Omar Pecho Dr. Kurt Pernstich Prof. Nils Reinke Remo Ritzmann Prof. Dr. Beat Ruhstaller Dr. Yasser Safa Dr. Guido Sartoris Benjamin Schmid Dr. Matthias Schmid Prof. Dr. J端rgen Schumacher Esther Spiess Lilian Toniolo

Lecturer Lecturer Research Associate Research Associate Research Assistant Lecturer, Head ICP Research Associate Research Assistant Research Associate Research Associate Research Associate Research Assistant Research Assistant Research Assistant Research Assistant Research Associate Research Associate Lecturer Research Assistant Lecturer Research Associate Research Associate Research Assistant Lecturer Lecturer Administrative Assistant Administrative Assistant

rebekka.axthelm@zhaw.ch gernot.boiger@zhaw.ch mathias.bonmarin@zhaw.ch peter.cendula@zhaw.ch samuel.hauri@zhaw.ch thomas.hocker@zhaw.ch lorenz.holzer@zhaw.ch lukas.kaufmann@zhaw.ch lukas.keller@zhaw.ch christoph.kirsch@zhaw.ch evelyne.knapp@zhaw.ch thomas.lanz@zhaw.ch kevin.lapagna@zhaw.ch markus.linder@zhaw.ch christoph.meier@zhaw.ch omar.pecho@zhaw.ch kurt.pernstich@zhaw.ch nils.reinke@zhaw.ch remo.ritzmann@zhaw.ch beat.ruhstaller@zhaw.ch yasser.safa@zhaw.ch guido.sartoris@zhaw.ch benjamin.schmid@zhaw.ch matthias.schmid@zhaw.ch juergen.schumacher@zhaw.ch esther.spiess@zhaw.ch lilian.toniolo@zhaw.ch

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Spin-off Companies

www.nmtec.ch Numerical Modelling GmbH works in the field of Computer Aided Engineering (CAE) and offers services and simulation tools for small and medium enterprises. Our core competence is knowledge transfer: we bridge the gap between scientific know-how and its application in the industry.

With our knowledge from physics, chemistry and the engineering sciences we are able to profoundly support your product development cycle. Numerical Modelling speaks your language and is able to conform to given constraints with respect to time and budget.

We often create so-called customer specific CAE tools in which the scientific knowledge required for your product is embedded. In this form, it is easily deployed within your R&D department and supports actual projects as well as improving the skills of your staff. Ask for our individual consulting service which covers all areas of scientific knowledge transfer without obligation.

www.fluxim.com FLUXiM AG is a provider of device simulation software to the display, lighting, photovoltaics and electronics industries worldwide. Our principal activity is the development and the marketing of the simulation software SETFOS which was designed to simulate light emission from thin film devices such as organic light-emitting diodes (OLEDs), thin film solar cells (organic and inorganic) and organic semiconducting multilayer systems.

Our company name FLUXiM is derived from flux simulation. Our software products are used worldwide in industrial and academic research labs for the study of device physics and product development. Check out our references and testimonials for more info. We develop swiss-made software in Switzerland and in addition also provide services such as consulting, training and software development, see our services page for more details.

www.winterthurinstruments.ch Winterthur Instruments AG develops measurement systems for fast non contact and non destructive testing of industrial coatings. These measurement systems can be used to determine coating thicknesses, material parameters (e.g. porosity) and contact quality (e.g. to detect delamination).

The system is based on optical-thermal measurements and works with all types of coating and substrate materials. Our measurement systems provide the unique opportunity of non-contact and non-destructive testing of arbitrary coatings on substrates.

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A.11

Location

ICP Institute of Computational Physics Technikumstrasse 9 P.O. Box CH-8401 Winterthur www.icp.zhaw.ch

Contact Thomas Hocker Phone +41 58 934 78 37 thomas.hocker@zhaw.ch

Administration Lilian Toniolo Phone +41 58 934 73 06 lilian.toniolo@zhaw.ch

TK-Building

TL-Building

Zurich University of Applied Sciences

School of Engineering ICP Institute of Computational Physics Technikumstrasse 9 P.O. Box CH-8401 Winterthur Phone +41 58 934 71 71 info.engineering@zhaw.ch www.icp.zhaw.ch