Research Report 2015

Zurich Universities of Applied Sciences and Arts www.zhaw.ch/engineering Research & Development Simulated intensity of scattered light above a rough Zinc Ox- ide surface used for optimizing solar cells. The lateral size is 4.5 um and the wavelength is 600 nm.

Simulierte Lichtintensität gestreut durch eine raue Zinkoxid Oberﬂäche für die Optimierung von Solarzellen. Die Kanten- länge ist 4.5 um und die Wellenlänge ist 600 nm. Contents

Preface 3

Vorwort 4

Projects 5 1.1 Komfortables Reisen durch Erfassung, Analyse und Postprocessing von 3D Daten zur Gleisvermessung...... 5 1.2 Mathe schützt den Menschen in der Masse...... 6 1.3 Liquid water modeling in PEMFC porous layers...... 7 1.4 Multi-phase modelling of a hydrogen generator...... 8 1.5 Electrical losses in hematite during photoelectrolysis...... 9 1.6 Development and optimization of patterned porous materials for thermo-neutral fuel cells...... 10 1.7 Towards the detailed understanding of coffee brewing...... 11 1.8 Improved cooling processes for chocolate production...... 12 1.9 Ohmic resistance of nickel inﬁltrated chromium oxide scales in solid oxide fuel cell metallic interconnects...... 13 1.10 New generation of high-performance air heaters...... 14 1.11 Numerical Simulation of Stacked OLEDs and Solar Cells...... 15 1.12 LED-based sun simulator for solar cell characterization...... 16 1.13 Impact of sand content on solute diffusion in Opalinus Clay...... 17 1.14 Fast transient simulation of semiconductor devices...... 18 1.15 CARDYN - Charge carrier dynamics in organic electronic devices...... 19 1.16 Fluxim Research and Development Support...... 20 1.17 Electrical interconnections in solar cells and modules...... 21 1.18 Rigorous simulation of light scattering...... 22 1.19 Simulation of heat transfer processes within a fuel cell system based on OpenFoam 23 1.20 Tentative modelling of the failure in Solid Oxide Fuel Cell...... 24 1.21 A model-based optimization of cooling tunnel processes...... 25 1.22 Simulation Software for DSSC Modules...... 26 1.23 Coulometric system with generator cell...... 27 1.24 Euler-Lagrangian model of particle laden ﬂows and deposition effects in powder coating...... 28 1.25 Simulation von Heizelementen für Heissluftgebläse...... 29

1 Institute of Computational Physics Research Report 2015

1.26 Optimierung von porösen Diaphragmen Modell- und simulationsunterstützte Mate- rialentwicklung...... 30 1.27 Simulation des Nano-Dosierverhaltens von nicht-Newtonschen Flüssigkeiten.... 31 1.28 Nondestructive Quality and Process Control of Thermal Spray Coatings...... 32 1.29 Pulverbeschichten mit Closed-Loop Regelung...... 33 1.30 Qualitätssicherung von Haftvermittlerschichtdicken in der Produktion von Drehschwing- ungsdämpfern...... 34 1.31 Entwicklung eines Messgeräts für die praktische Anwendung der Thermischen Schicht- prüfung an Kunst und Kulturgut...... 35 1.32 Blaues Licht aus neuen Materialien...... 36 1.33 Herstellung von Perowskit-Solarzellen...... 37 1.34 Modellbasierter Reglerentwurf für die Temperaturregelung eines Kryostaten..... 38

Appendix 39 A.1 Student Projects...... 39 A.2 Scientiﬁc Publications...... 41 A.3 Book Chapters...... 43 A.4 News Articles...... 43 A.5 Conferences and Workshops...... 43 A.6 Public Events...... 47 A.7 Patents...... 47 A.8 Prizes and Awards...... 47 A.9 Teaching...... 47 A.10 Spin-off Companies...... 50 A.11 ICP-Team...... 51 A.12 Location...... 52

www.zhaw.ch2 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

Preface

In a February 2015 e-mail, Beat Ruhstaller included a postscript: By the way, we are looking for the successor to my successor. In saying so, he wanted to draw my attention to the ICP’s recent announcement of a competition for their head position. At the time, I considered myself lucky to be the managing director of the company Vela Solaris and I had certainly not been looking for a new job. Beat and I had been close friends for a long time, thus giving me the opportunity to get to know the ICP. Like déjà-vu, Beat’s suggestion came as an incredibly tempting second chance: 12 years before, Beat had spoken to me about Fluxim, asking if I wanted to play an active role in establishing and organising the company with him. Though I declined his offer at the time, I felt a slight pang of regret shortly thereafter. In those days I had two options: the organic LED at the University of Applied Sciences in Win- terthur, or a similar research opportunity at the Institute for Solar Technology SPF in Rapperswil. Both offered the potential for subsequent spin-off projects, and a simulation algorithm had twice been at the core of innovation. Thanks to my former expertise in the optoelectronic-modeling field, I felt more confident with Beat’s field; nevertheless, I brought myself to finally take a slightly bigger step into the solar energy field. I was certain that renewable energy sources would have become an important issue and that designing physics-based simulation software would have contributed to the greater success of solar systems. Thus, at the end of 2006 I co-founded the company Vela Solaris in Rapperswil with the team of the long-standing college project called Polysun. We were lucky with our timing, as we entered the market in a prime position for the energy revolution to come. Instead of marketing our engineering services, we decided to sell our software licenses internationally. Today, Vela Solaris is a stable company whose simulation software Polysun is well- positioned in the market, acting as a planning tool for several tens of thousands of active users. During the course of the company’s history, its innovative projects have been of fundamental importance, helping the software against rival products. And so, since October 2015 I have been the Head of the ICP. We found a qualified replacement for the management of Vela Solaris. I granted the ICP my network and access to the Polysun source code. Some of Polysun’s innovative projects in recent years have been highly research- oriented and have had to be put on hold. These projects have now found their respective niches within the framework of the ICP’s multiphysics-modeling focus and the greater energy field from the School of Engineering (SoE). Talks with our hardware partners are already under way, but our vision is fortunately focused on the long term. As far as Bachelor’s theses are concerned, we have already tackled various topics. Moreover, ICP has a tradition of proffering ambitious projects and supporting students through various spin-off companies, thereby giving them the opportunity to perform excellently within a short working period. Interestingly, these research projects have been accompanied by new synergies in teaching projects, built upon my previous work experience: for years now, Vela Solaris has offered continuing education and has become involved in vocational education and in working with technical colleges. I can directly implement the results of such ex- periences to the ZHAW teaching. Thanks to computer simulation, a common feature throughout my career, I feel like my current position at ICP is exactly the right one. I find the diversity of the work fields really stimulating. In my opinion, spearheading the core of these applications within the framework of modeling and numerics is an important communication task. Alongside the simulation experience, its practical applications are also crucial: valuable contributions to different areas have only been achieved thanks to good industrial partners. Finally, and importantly, innovation capacity sometimes rests on thinking out of the box and bringing together different branches of knowledge. I would like to sincerely thank Beat for thinking of me one year ago. That one line in his e-mail back then was a perfect example of spontaneously thinking out of the box. Thanks also to the ICP team for their warm welcome and sound support during my period of vocational adjustment. Congratulations on your achievements and their presentation in this annual report !

Andreas Witzig, February 2016

Zürcher Fachhochschule3 www.zhaw.ch Institute of Computational Physics Research Report 2015 Vorwort

Im Februar 2015 hatte Beat Ruhstaller im PS einer E-Mail geschrieben, Übrigens, wir suchen den Nachfolger meines Nachfolgers, und machte mich damit auf die Ausschreibung der ICP- Institutsleiterposition aufmerksam. Ich war damals als Geschäftsführer der Firma Vela Solaris glücklich mit meinem Job und überhaupt nicht auf Stellensuche. Mit Beat verbindet mich eine langjährige Freundschaft und dadurch hatte ich auch das ICP bereits kennen gelernt. Beats Hin- weis war für mich ein Déja-Vu und eine unglaublich interessante zweite Chance: Vor 12 Jahren hatte mir Beat von Fluxim erzählt und mich angefragt, ob ich bei der Firmengründung aktiv mitwirk- en und mit ihm zusammen die Firma aufbauen möchte. Ich hatte ihm damals abgesagt und dem Entscheid noch einige Zeit etwas nachgetrauert. Ich hatte damals zwei Optionen: neben dem Thema Organische LED an der Fachhochschule in Winterthur gab es am Solartechnik-Institut SPF der Hochschule Rapperswil ein ähnliches Ange- bot. Bei beiden bot sich die Chance für eine spätere Spin-Off Gründung und zweimal war ein Simulationsalgorithmus Kern der Innovation. Obwohl ich mit meinem damaligen Arbeitsgebiet Optoelektronik-Modellierung in Beats Thema besser verwurzelt war, hatte ich mich letztlich für den etwas grösseren Sprung in das neue Anwendungsgebiet Solarenergie gewagt. Ich war überzeugt, dass erneuerbare Energiequellen zu einem grossen Thema werden sollten und dass eine auf physikalischer Simulation basierende Planungssoftware einen Beitrag zur Verbreitung von So- laranlagen liefern könnte. Mit dem Team des langjährigen Hochschulprojektes Polysun hatte ich dann in Rapperswil Ende 2006 die Firma Vela Solaris gegründet. Wir hatten Glück mit dem Timing und konnten uns gut positionieren für die darauf folgenden Energiewende-Jahre. Wir hatten uns entschieden, nicht unsere Ingenieurleistung sondern Softwarelizenzen international zu verkaufen. Inzwischen ist Vela Solaris ein stabiles Unternehmen und die Simulationssoftware Polysun mit mehreren zehntausend aktiven Nutzern als Planungswerkzeug gut im Markt verankert. Während der ganzen Firmengeschichte haben Innovationsprojekte eine zentrale Rolle gespielt und der Soft- ware zu einem Vorteil gegenüber der Konkurrenz verholfen. Nun bin ich seit Oktober 2015 Institutsleiter des ICP. Für die Geschäftsleitung von Vela Solaris hatten wir einen guten Nachfolger gefunden. Mein Netzwerk und den Zugang zum Polysun Quell- code bringe ich mit ans ICP. Bei den Polysun-Innovationsprojekten gab es in den letzten Jahren einige, die zu starken Forschungscharakter hatten und deshalb zurückgestellt werden mussten. Im ICP-Schwerpunkt Multiphysik-Modellierung und dem übergeordneten SoE-Thema Energie haben diese Projekte nun den idealen Rahmen gefunden. Die Gespräche mit den entsprechenden Hard- warepartnern laufen bereits, aber zum Glück haben wir hier einen langfristigen Horizont. Auf Stufe Bachelorarbeiten haben wir bereits mehrere Themen in Angriff genommen. Ich konnte dabei an die ICP-Tradition anknüpfen, ehrgeizige Arbeiten auszuschreiben und die Studenten mit Unter- stützung der Spin-Off Firmen auf ein Niveau zu bringen, auf welchem sie in der kurzen Dauer der Arbeit Grossartiges leisten können. Neben den Forschungsprojekten bieten sich interessan- terweise in der Lehre weitere Synergien zu meiner früheren Tätigkeit: Vela Solaris bietet schon seit Jahren Weiterbildung an und engagiert sich in der Berufsbildung und an Fachhochschulen. Die Erfahrungen daraus kann ich in der ZHAW-Lehre direkt umsetzen. Mit der Computersimu- lation als Klammer über meine beruﬂiche Laufbahn bin ich nun am ICP genau am richtigen Ort angekommen. Neu und aufregend ist für mich die Vielfalt der Arbeitsgebiete. Ich sehe es als wichtige Kommunikationsaufgabe, den gemeinsamen Kern dieser Anwendungen in der Model- lierung und der Numerik aufzuzeigen. Neben der Simulationserfahrung ist dabei die Verbindung zur Anwendung entscheidend. Nur mit guten Industriepartnern können in den vielen Themen wertvolle Beiträge geleistet werden. Und nicht zuletzt liegt die Innovationskraft auch darin, dass man über den Tellerrand schaut, manchmal out of the box denkt und die verschiedenen Disziplinen miteinander verbindet. Gerne möchte ich Beat danken, dass er vor einem Jahr an mich gedacht hat. Die Zeile im E-Mail von damals war ein typisches Beispiel für spontanes thinking out of the box. Danke auch dem ICP- Team für den herzlichen Empfang und die gute Unterstützung während meiner Einarbeitungszeit. Gratulation für die Erfolge und deren Präsentation im vorliegenden Jahresbericht !

Andreas Witzig, Februar 2016 www.zhaw.ch4 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.1 Komfortables Reisen durch Erfassung, Analyse und Post- processing von 3D Daten zur Gleisvermessung

Wir alle wünschen uns eine zuverlässige und leistungsfähige Verkehrsinfrastruktur; insbesondere im Bahnbereich. Damit Bahngesellschaften dies ermöglichen können benötigen sie ein umfassendes Infrastrukturdatenmanagement, zuverlässige Qualitätskontrollen im Bauprozess sowie die umfassende Kenntnis über den Zustand und die Anforderungen an das Streckennetz

Contributors: R. Axthelm Partners: IMS, Amberg Technologies Funding: KTI Duration: 2013–2016

Fig. 1: IMU gestützte Gleisvermessung, Bildquelle: http://www.ambergtechnologies.ch.

ARTIS ist ein neuartiges Informationssystem zur dung geeigneter, mathematischer Methoden Soft- Erfassung und Analyse von 3D Daten zur Gleis- warekomponenten entwickelt, die in der Lage sind vermessung. 3D Scandaten werden mit Daten aus aus einer Schienenachse die passenden Desi- bildgebenden Sensoren überlagert und gleisspe- gnelemente, das sind Geraden, Klothoiden Kreis- ziﬁsche Parameter werden berechnet. Diese Ver- und Parabelbögen, zu berechnen. Die Schienen- fahren sollen auch angewendet werden, falls die achse selbst ist durch eine IMU gestützte Gleis- Messdaten aus einem Drittsystem stammen. Au- messmethode ermittelt worden und liegt in Form ßerdem soll ARTIS Anwendungsfälle der Gleisver- von verrauschten Daten vor. Dieser Teil der Soft- messung abdecken, bei denen nur unvollständige ware berechnet Designelemente, die bestmöglich Designdaten vorliegen. Die aktuellen Anwendun- den Verlauf der vermessenen Trasse abzeichnet. gen stützen sich zum Beispiel auf die Verfügbar- Diese neuen Berechnungsverfahren kommen zur keit von Designelementen, die allerdings nicht im- Anwendung bei der Erneuerung bzw. Wartung be- mer zur Verfügung stehen. stehender Eisenbahntrassen. Insbesondere auch Zusammen mit dem ICP werden unter Verwen- dort, wo vorgängig keine Plandaten vorliegen.

2200 2150 2100 2050 2000 -1687 -1487 -1287 -1087 -887 -687 -487 -287 -87 113 313

Fig. 2: Automatisierte Designelementberechnung aus den verrauschten Trassenpositionsdaten.

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1.2 Mathe schützt den Menschen in der Masse

Wie können wir Gefahren bei Großveranstaltungen verhindern? gehört zu den drängenden Fragen unserer Zeit. Ein Interesse, dass Jedermann im öffentlichen Raum, insbesondere die Verantwortlichen wie Polizei, Veranstalter und Raumplaner haben. Zusammen mit der Zürcher ASE GmbH entwickelt das ICP präzise Modellrechnungen und eine Simulations- software für Menschenströme.

Contributors: R. Axthelm Partners: ASE GmbH Funding: KTI Duration: 2013–2016

Fig. 1: Selbst bei einer gewöhnlichen Leerung eines Stadions kann es allein durch das Aufkommen hoher Dichten an manchen Stellen zu einer erhöhten Panikgefahr kommen, Quelle: http://research.ptvgroup.com.

Jeder kennt das beklemmende Gefühl, wenn dellierungsparameter dient, Fig. 2. Der Vorteil an man dichtgedrängt und bewegungsunfähig in einer dieser Stelle besteht in der Möglichkeit der Ein- Menschenansammlung verharren muss, so dass ﬂussnahme auf die bestehende Situation aus Be- man kaum atmen kann; etwa vor einer Konzert- nutzersicht. Derzeit werden Validierungsrechnun- bühne, beim Verlassen der Tribüne eines Stadions gen bezüglich Evakuierungszeiten durchgeführt. oder in einer Großstadt-U-Bahn während der rush- Zugrunde liegen experimentelle Daten des IAS hour. Dies motivierte uns, zusammen mit der Fir- (Forschungszentrum Jülich). Umgekehrt lässt sich ma ASE GmbH, eine entsprechende Simulations- durch pFlow ermitteln welche Charakteristika ei- software zu entwickeln. Die Software pFlow ba- ner analytischen Beschreibung des Fundamental- siert auf einem makroskopischen Modellansatz. diagramms speziﬁsche Situationen qualitativ und Das heißt, dass eine Menge von Personen als quantitativ gut abbilden. Kontinuum aufgefasst wird, bei der nicht die Bewe- gung jedes Einzelnen im Fokus steht, sondern die 1.8 zu jedem Zeitpunkt resultierende Dichteverteilung. 1.6 Basierend auf dem Modellansatz 1.4 ∇Φ 1 1.2 % − ∇ · % f(%) = 0 , |∇Φ| = , 1 t |∇Φ| f(%) 0.8 wie er bisher in der Literatur zu diesem Thema

Geschwindigkeit 0.6 zu ﬁnden ist, wurde eine Modellbeschreibung er- 0.4 arbeitet, die in gewissem Sinne das Ähnliche be- 0.2 rechnet, numerisch aber stabiler ist. Die neuen 0 Gleichungen werden in Kürze in [1] publiziert wer- 0 1 2 3 4 5 6 Dichte den. % beschreibt die Dichteverteilung im Raum Fig. 2: f(%) (—) ermittelt aus empirischen Daten (◦). und ∇Φ die Bewegungsrichtung. Das sogenann- te Fundamentaldiagramm f(%) liefert die dichte- Literature: abhängige Geschwindigkeit von Fußgängern, die [1] R. Axthelm, Trafﬁc and Granular Flow ’15, aus empirischen Daten ermittelt wird und als Mo- Springer, accepted. www.zhaw.ch6 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.3 Liquid water modeling in PEMFC porous layers

For a successful commercialization of polymer electrolyte fuel cell (PEFC), a high speciﬁc power output must be achieved. In this workpackage, as a part of the project funded by the Swiss National Science Foundation and the Swiss Federal Ofﬁce of Energy, we aim at simulating the pore-scale water distribution in a fuel cell as to improve the parameterization of the transport properties and improve the macroscopic modeling of the device.

Contributors: J. Schumacher, L. Capone, J. Dujc, P. Marmet, A. Lamibrac, F. Büchi Partners: Paul Scherrer Institute Funding: SNSF, Swiss Federal Ofﬁce of Energy Duration: 2014–2017

In order to improve the performance of polymer MC simulations at different water saturation lev- electrolyte fuel cells, the effect of the liquid wa- els were applied by using the experimentally deter- ter blocking the pores of the Gas Diffusion Layer mined pore structure. Also virtual structures, gen- (GDL) must be mitigated. Macro-homogeneous erated by the GeoDict software have been used as models treat a porous medium as an effective geometric input for the algorithm. The results are continuum involving volume-averaged quantities encouraging: we can simulate the water distribu- to ﬁnd transport parameters such as permeability tion using the energy minimization procedure (see and conductivity, while the effect of the water hin- Figures). dering the pores occurs at a lower scale.

Fig. 2: Simulated 2D water distribution (blue) in the same solid (brown) porous structure as in Fig. 1. Fig. 1: Experimental 2D water distribution (blue) in a solid (brown) porous structure obtained from a imbibition experiment [4].

We implemented a Monte Carlo (MC) algorithm to determine the equilibrium distribution of the liquid water in the open pore space of gas diffusion layers. The algorithm accounts for the surface free energy based interactions between water clusters in the open pore space. Those interactions occur at the voxel level. There- fore, the collective behavior of the water aggrega- Fig. 3: Equilibrium water distribution (blue) on a 3D GDL tion and formation of water clusters are expected structure rendering (red). to behave like a classical statistical ensemble. The energy of each voxel processed by the MC code, Literature: is generally depending on the interfacial interaction [1] L. Capone, et al., J. Power Sources, to be pub- energies with its neighbours. It is calculated as to lished. catch the natural tendency of the system to reach [2] K. Seidenberger, et al., J. Power Sources, 239, its minimum energy state, equilibrating the water 628–641, 2013. distribution in the GDL. [3] D. Landau, et al., A guide to Monte Carlo simu- The algorithm has been applied to sets of tomo- lations in statistical physics, 2014. graphic data of GDLs, where both the dry and the [4] A. Lamibrac, et al., J. Electrochem. Soc., 163, wet state of the GDL was investigated. Then, the F202-F209, 2016.

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1.4 Multi-phase modelling of a hydrogen generator

The development of hydrogen generators for direct use with a polymer electrolyte fuel cell (PEFC) is very attractive for applications as decentralized power sources. On-demand production of hydrogen from formic acid can replace the conventional high-pressure hydrogen storage. In this work, we developed and partially validated a computational model of such a device.

Contributors: V. Orava, J. O. Schumacher, P. Cendula Partners: EPFL, Granit SA, Charles University (CZ), PSI Funding: Swisselectric Reasearch, CCEM Duration: 2014–2015

Liquid formic acid (HCOOH) is decomposed into the gas and the liquid phase and a constant boiling hydrogen and carbon dioxide over a ruthenium cat- mixture of formic acid and water. alyst when heat is added. Although the homoge- The gas flow rate follows the Arrhenius exponen- neous catalyst (liquid phase) was sufficiently sta- tial law and enabled us to extract two parameters ble and active for several months at EPFL, traces - the activation energy 93.6 kJ and the frequency of water and formic acid in the product gas prevent factor 1.24×1010 Hz. In doing so we proceeded the direct supply of a PEFC. The heterogeneous by estimating the average temperature of the reac- catalyst (solid phase) can produce higher quality tor by iteration between measurements and simu- of the product gas required for PEFCs and thus it lations in the following four steps: First, we derive is preferred for scaling up from the laboratory tests the parameter values from the measurements us- to the commercial prototypes. A baseline model of ing Treact as the average. Second, we perform sim- the gas and liquid flow, the chemical reaction and ulations with the derived values and, consequently, heat transfer within the hydrogen generator was compute the average temperature Tav within the achieved in the first project year. reactor (using Tout as the heating boundary tem- Several changes of the catalyst support and gen- perature). Third, we use it to derive the corrected erator construction in the second year lead to the parameter values. Finally, we perform a simulation first reproducible measurements of the hydrogen with corrected parameter values and compare the generation at EPFL and Granit SA, Fig. 1. The simulated and measured temperature within the temperature in the generator was measured only reactor Treact and this is shown with experimental at a single point due to technical limitations. data in Fig. 1. We thus conclude that our model is partially validated with the single temperature D 10 Uniform T reading available from the experiments. In addi- min Simulated Tav L

@ tion, the ﬂow pattern in the (transparent) generator

L 8

2 T Measured react qualitatively agrees with the simulation results - ris- CO 6 Treact Simulated + 2 H L ing in the center and sinking close to the perimeter. H H 4 H L

Rate 2

Flow 0 75 80 85 90 95 100 105 110 Temperature C

Fig. 1: Gas ﬂow rate as a function of@ theD temperature. The gas production of a generator with uniform temperature is shown for comparison.

The experiments demonstrate the importance of space abundance between the inner heating tubes Fig. 2: Simulations of the hydrogen generator for inlet temperature 99 ◦C, catalyst packing 5% vol., pressure 3 bar. and the outer reactor surface, as one of the reactors experienced ﬂoating of all catalyst particles Variation of the generator dimensions and position on the liquid surface. Hence, the following exten- of the heating tubes (outer and inner) is undergo- sions to the model were incorporated: the motion ing in order to ﬁnd the maximum generator perfor- of the solid catalyst phase, mass transfer between mance at the given working and space constraints. www.zhaw.ch8 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.5 Electrical losses in hematite during photoelectrolysis

Electrolysis of water using solar energy in a single device would signiﬁcantly speed up transition to hydrogen energy economy. One approach for construction of such device is the semiconductor-based photoelectrochemical (PEC) cell. Understanding the various recombination losses in the PEC cell through physical model is the starting point for the improvement of its efﬁciency.

Contributors: P. Cendula, L. Steier, M. T. Mayer and J. Schumacher Partners: Laboratory of Photonics and Interfaces, EPF Lausanne, Switzerland Funding: Swiss Federal Ofﬁce of Energy Duration: 2015–2017

Hematite (Fe2O3) is an earth-abundant, stable and in the model and the resulting photocurrent j2 is non-toxic semiconductor oxide suitable as a pho- obtained. The area between j2 and j1 therefore toanode for photoelectrolysis. Its low photocurrent presents unambiguously the charges lost by bulk is so far limited by large bulk and surface recombi- recombination. Finally in (d), also surface recom- nation losses. To quantify these losses, we have bination term is included in the calculation and the coupled our validated optical model of the PEC area between j3 and j2 gives solely losses by the cell to the drift-diffusion model of the electronic surface recombination. charge transport. Note that during studies of indi- The wavelength-dependent performance of vidual electrodes of the PEC cell, an ideal counter- hematite and the accompanying losses are com- electrode such as platinum is used to focus entirely pared in the graph of incident photon-to-current on the properties of the electrode. For the same efﬁciency (IPCE) of the PEC cell, Fig. 2. When reasons electronic currents are reported, and not all absorbed photons would be converted to pho- volume of produced hydrogen. tocurrent (ideal case), the IPCE of hematite would be equal to the absorptance in hematite layer and reach 50% at 350 nm. In comparison, the measured IPCE and IPCE simulated with the optical model (OM) qualitatively agree and reach 10% at 350 nm, the losses being caused by bulk recombination, slow water oxidation kinetics and small hole diffusion length. We also show that IPCE calculated with the Lambert-Beer law is overesti- mating the IPCE from the measured data and OM simulations.

Fig. 1: Stacked photocurrent-voltage diagram of the electrical losses in the PEC cell with 12 nm of hematite for 1 sun illumination. Potential is reported versus reversible hydrogen electrode (RHE).

In Fig.1, we calculated photocurrent-voltage curves for following scenarios: (a) jmax,OM , perfect conversion of every absorbed photon to photocurrent, (b) j1 without any recombination, (c) j2 with bulk recombination, (d) j3 with bulk and surface recombination. For (a), all absorbed photons are ideally converted to photocurrent without considering any charge separation issues. For (b), only some charges are separated by the electro- Fig. 2: Comparison of the measured and calculated IPCE for 1.4 V vs. RHE. static field, but no recombination (bulk nor surface) at all is included in the calculation. The area be- The severe losses quantified in the PEC cell must tween jmax,OM and j1 can thus be described as be individually addressed to reach the 15% solar- photocurrent loss due to charge separation. In the to-hydrogen efficiency target and combined effort (c) case, the bulk recombination term is included of experiments and theory is necessary.

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1.6 Development and optimization of patterned porous materials for thermo-neutral fuel cells

The goal of the Swiss Competence Center for Energy Research - Efﬁcient Technologies and Systems for Mobility (SCCER Mobility [1]) is to develop the knowledge and technologies essential for the transition of the current fossil fuel based transportation system to a sustainable one. One step towards to reach these goals is the development of a novel concept of a thermo-neutral fuel cell. This will allow a simpliﬁcation of the overall fuel cell system and a reduction of the price of fuel cell powered vehicles.

Contributors: J. Dujc, A. Forner-Cuenca, M. Cochet, L. Capone, J. Schumacher, P. Boillat Partners: Paul Scherrer Institut Funding: CTI Duration: 2014–2017

The cooling of a thermo-neutral fuel cell is realized hydrophilic regions [2]. The new GDLs were first by the evaporation of the water that is additionally characterized experimentally at PSI by measuring introduced into the fuel cell and also by the evap- the local saturation as a function of the capillary oration of the water produced during the fuel cell pressure applied. Neutron radiography was used operation by the oxygen reduction reaction. The as imaging technique. This allows for the quan- presence of liquid water in a PEFC has both pos- tification of the water thickness. In a second step, itive and negative effects. On the one hand side the team at the ICP focused on the numerical mod- water is beneficial since, besides the cooling ef- eling and the analysis of the behavior of the new fect, a high water content in the membrane in- components. We focus on the membrane elec- creases the protonic conductivity and thereby the trode assembly model which consists of the cath- overall fuel cell efficiency. On the other hand the ode side GDL and the MPL, the cathode side cat- liquid water accumulates in the porous gas diffu- alyst layer, the membrane, the anode side CL, and sion layers (GDL) and thus limits the transport of the anode side GDL with MPL, Fig. 1. A special at- oxygen. This may lead to a reduction of the fuel tention was put on modeling of the two-phase flow cell performance. of water (e.g. [3]) in the porous components of the membrane electrode assembly, Fig. 2. The goal for 2016 is to further develop the existing models and to find the optimal pattern design, which will ensure the best behavior of the fuel cell.

Fig. 1: Simulated distribution of the temperature field [◦C] in an isolated section of a membrane electrode assembly at 0.2 V. The temperature is the highest in the middle where the chemical reactions and the ion transport take place. In the current stage of the model the temperature field is not yet coupled to the two-phase flow. Therefore, there is no Fig. 2: The liquid water saturation distribution in the hy- in-plane variation of the temperature visible. drophilic treated GDL. The water is accumulated in the hydrophilic regions while the hydrophobic parts of the GDL and The focus of our work in the past year was on the microporous region (below) repel the water. the design and analysis of new GDLs, that are Literature: capable of better removing water from the elec- [1] http://www.sccer-mobility.ch. trodes towards the flow field in order to guaran- [2] A. Forner-Cuenca et al., Advanced Materials, tee access for the gases to the electrodes under 27, 41, 6317–6322, 2015. wet conditions. The new GDL design, which was [3] J.T. Gostick et al., Journal of Power Sources, developed by our partner, the Paul Scherrer Insti- 194, 1, 433–444, 2009. tut, implements a succession of hydrophobic and www.zhaw.ch 10 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.7 Towards the detailed understanding of coffee brewing

Making excellent coffee is an art. Like cooking, it largely depends on the quality of the used ingredients. However, in addition, how the roasting, grinding and actual brewing processes are performed has crucial impact the resulting coffee as well. This project represents a first step towards the detailed understanding of the flow of hot water through the coffee bed during the brewing process using micro-CT data of ensembles of coffee grains as input for 3D flow simulations.

Contributors: L. Holzer, T. Hocker, O. Stenzel Partners: A. Glöss, C. Yeretzian, ZHAW Fachstelle für Analytische und Physikalische Chemie Funding: Swiss Food Research Duration: 2015

Making excellent coffee is an art mastered best pressure during brewing will lead to a specifically by experienced baristas. It requires high-quality tasting coffee beverage. The collective effect of roasted coffee beans, an excellent coffee grinder all of the above mentioned parameters should be- and an excellent coffee machine. However, these come apparent in the time-dependent distribution are just mandatory prerequisites. In addition, it of residence times of the water flowing through the is the experience of the barista in how to do the brewing chamber. These residence times can be grinding, filling of the brewing chamber and per- extracted from flow simulations that take the 3D mi- forming the actual brewing that makes the differ- crostructure of the coffee bed as input, see Fig. 2- ence between an excellent coffee and an average 3. one. For example, rather large coffee grains will lead to short residence times of the water flowing through the brewing chamber. This results in weakly tasting coffee. On the other hand, rather small coffee grains can lead to clogging and chan- neling effects resulting again in weakly tasting coffee. However, small coffee grains also cause long residence times resulting in bitterly tasting coffee. In any case, knowing the distributions of residence times of the water flowing through the brewing chamber would represent a detailed fingerprint of Fig. 2: RealBsp 3D'Simula7on'des' microstructuresFliessverhaltens of a dry coffee:' bed obtained fromFlow micro-CT simulations data,Geschwindigkeitsfeld in see dry also coff [1].ee bed ' the performance of the brewing process and therefore could be correlated with the resulting coffee high pressure flow low pressure flow quality. This is exactly the idea behind this prelimi- nary study, see Fig. 1.

coffee beans design brewing roasting chamber milling water flow through coffee bed controlling operation conditions p(t), T extraction process (from fluid element viewpoint) "fluid element” brewing process grain water flow trough time- characteristics small channels dependent microstructure (e.g bimodal PSD) large channels s

filling → large & small channel flow → only large channel flow (particle packing) 3D flow imaging simulation omography residence t 5 ! ! !3 !4 3D times 1 2 Fig. 3: Simulations of water flow field through coffee bed for two different external pressures, see also [2].

coffee quality 2 aroma, yield, crema Literature: Fig. 1: Concept of analysing coffee brewing process by per- [1] Del Nobile et al., Applications of tomography in forming flow simulations and extracting residence times. food, Industrial Tomography, Ed. M. Wang, Wood- A specific type of roasting and grinding of spe- head publishing, 693–712, 2015. cific types of coffee beans provides specific coffee [2] M. Petracco, Percolation, Espresso coffee, the grains. Then the filling of a specific type of brew- science of quality, Eds. A. Illy, R. Viani, Elsevier, ing chamber and the control of temperature and 259–289, 2005. Zürcher Fachhochschule 11 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.8 Improved cooling processes for chocolate production

The crystallization of chocolate during the manufacturing process is vital to the characteristics of the ﬁnal product. We investigated how both advanced computer modelling methods and new inline measurements can be used to optimize crystal formation in chocolate in order to ultimately improve the taste and storage life chocolate products.

Contributors: P. Fahrni, R. Heusser, T. Hocker, Y. Safa Partners: ZSN, IFNH-ETHZ, Max Felchlin AG and additional industrial partners Funding: CTI Duration: 2013–2016

Chocolate is usually characterized using labora- temperatures, humidities and heat ﬂuxes while the tory equipment under ideal conditions, and often chocolate moulds travel through the cooling tun- it is not clear how closely these conditions mimic nel. Despite its small size, this logger has an un- the real production process. Therefore, our ap- matched performance, containing 14 channels and proach to making better chocolate has both an ex- being able to store data for up to 8 hours. perimental and a theoretical element. On the one Concerning the modeling of the actual chocolate hand, we use sophisticated inline measurements solidiﬁcation under production conditions, we es- to monitor the crystallization behavior of chocolate tablished a link to differential scanning calorimetry under real production conditions and, on the other (DSC) data to assess the crystallization and melt- hand, we use these data to validate our computer ing behavior under idealized lab conditions. A typ- models, which then can be used to explore differ- ical example of the model-based analysis of DSC- ent optimization scenarios [1]. An overview of the data of seeded cocoa butter, provided by L. Rej-

employedOverview modelling methods activities is given in Fig. 1. manFitting of hom. IFNH-ETHZ, cryst. model to is cocoa shown butter in Fig.DSC-data 3.

Production tests optimal sensor optimize mould placement and cooling tunnel cooling at -1 ºC/min with 0.1 % seeds re-heating at 4 ºC/min parameters spatial heat finalfinal fractions fractions α s1 == 143, s2%,= 83,βV u== 8314, %, m = β0VI = 3 % final finalfractions fractions α s1 == β0,V s2= β=VI0, = u =0 0,% m, =m100 = 100 % sensor testing conduction 0.00 models models model fit initial 1.5 -0.05 composition model fit temperatures, DSC data DSC data ) )

g 0.10

- g / DSC 1 heat-ﬂuxes, humidity, / e 1.0 W STAR System W ( US-detachment ( Innovative Technology -0.15 Versatile Modularity Jdsc -0.20 Jdsc 0.5 Swiss Qualitysensor platforms for inline tests -0.25 0.0 5 10 15 20 25 30 0 10 20 30 40 T (ºC) model T (ºC) understand prediction predict cryst. stable1VI stable2V unstable total βstable1VI cryst βstable2V cryst αunstable cryst totaltotal β cryst β cryst α cryst total Lab tests raw materials, formation in cooling get cryst. kinetics 1.5 tunnels 0.00 m → α -0.05 VI m → β V V β → m ) 1.0 ) m → β g

0.10 /

g - /

homogeneous spatial W ( W crystallization crystallization ( -0.15

Thermal Analysis Excellence Analysis Thermal 0.5 Jdsc models models Jdsc -0.20 α → m -0.25 βVI → m 0.0 -0.30 α → βV βV → βVI Fig.Thomas 1: Hocker, Overview ZHAW of ICP’s modeling2 and inline measurementSeptember 22, 2015 5 10 15 20 25 30 10 20 30 40 Differential Scanning Calorimetry T (ºC) T (ºC) for activitiesall Requirements within the Coolcon research project. 5 October 13, 2015 Commercial products used by chocolate makers Fig. 3: Fitting extended Révérend crystallization model [2] to seeded cocoa butter DSC data and predicting the DSC- for inline measurements did not meet our require- contributions of the various phase transformations. ments, so we had to develop our own hardware. This 0D cystalization model serves as input for the more sophisticated cyrstalization model developed by Y. Safa. Safa’s model takes into account the spatial dependencies and nonhomogeneous thermal boundary conditions present under production conditions, see additional contribution by Y. Safa within this report. Literature: [1] T. Hocker, Perfecting the chocolate making pro- Fig. 2: Xocolog data logger developed by P. Fahrni to per- cess, International Innovation, 2015. form inline temperature, heat-ﬂux and humidity measure- [2] B.J.D. Le Révérend, I. Smart, P.J. Fryer, ments. S. Bakalis, Modelling the rapid cooling and casting As an example shown in Fig. 2, we developed our of chocolate to predict phase behaviour, Chemical own data logger the size of an iPhone to record Engineering Science, 66, 1077–1086, 2011.

www.zhaw.ch 12 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.9 Ohmic resistance of nickel inﬁltrated chromium oxide scales in solid oxide fuel cell metallic interconnects

Oxide scale formation on metallic interconnects contributes to the overall degradation of solid oxide fuel cell (SOFC) stacks. On the anode side, thermally grown oxide scale might contain additional nickel, nickel oxide, or nickel chromium spinel phases – depending on the stack composition and the applied operation conditions. We investigated the inﬂuence of Ni on the electrical conductivity of oxide scales since this can provide new strategies to signiﬁcantly decrease the ohmic losses associated with anodic oxide scale formation.

Contributors: M. Linder, T. Hocker, L. Holzer, O. Pecho Partners: IMPE, DLR-Stuttgart, FH-Esslingen, Hexis AG Funding: Swiss Federal Ofﬁce of Energy, Swiss Electric Research Duration: 2012–2015

Oxide scale formation on the anodic side of metal- and spatial arrangement, i. e., on their microstruc- lic interconnects (MICs) leads to complex mi- tures. This is explained in more detail in Fig. 3, crostructures and involve a multitude of different where changes in the main electrical current path- SEMchemical image species, REM121797 see Fig. 1. ways are associated with microstructural and com-

resin positional changes. remaining anode layer a b c

NiO 3Ni 2+ Ni Ni NiO Ni-mesh NiO Cr 2O3 iNiCr 2O4 ii NiO 2 3 Cr O 3+ gas gap 2Cr

i) gas gap/NiCr 2O4 spinel formation zone Ni Cr 2O3 NiO Cr 2O3 2+ 3+ 3Ni + 4Cr 2O3(g) = 3NiCr 2O4 + 2Cr Cr 2O3 Cr 2O3

ii) NiCr 2O4/NiO spinel formation zone 3+ 2+ Ni NiO 2Cr + 4NiO = NiCr 2O4 + 3Ni

internal oxidation zone d e f

Anode pore Ni-mesh CFY H2O H2 flow channel O2(g) Ni(OH) 2(g) Cr2N Cr2O3 + Ni-O-OH ads VO VO VNi Ni(s) int. oxi. zone Cr 2O3 200 µm interconnect Cr 2O3 Cr 2O3

CFY NiCr 2O4 spinel Cr 2O3 Cr 2O3 Fig. 1: Cross section of a MIC operated in a Hexis SOFC stack at 900 ◦C running on CPOx reformed natural gas for 40000 h including 15 redox cycles [1]. g h

In a series of experiments using pellets made Cr 2O3 pores of chromium oxide (Cr2O3) mixed with different Ni NiO amounts of Ni-particle the electrical conductivity of NiCr 2O4 spinel main electric current pathway such ensemblesElectrical conductivity variation has beenbased on specific investigated, microstructure changes see during Fig. 2. heat exposure under different atmospheres in Nickel containing Cr2O3 layers Ostwald ripening

Cr2O3 matrix Cr2O3 matrix Cr2O3 matrix Fig. 3: Microstructure changes during the evolution of the Ni NiO spinel NiCr2O4 Ostwald formation spinel rippening Ni containing Cr2O3 pellets under reducing, oxidizing and dispersed Ni Ni re-reducing conditions and corresponding changes in main NiCr2O4

eff Ni Ni electrical current pathways. spinel decomposition 20 µm 20 µm 20 µm NiO formation It turns out that redox-cycles and the according transformations between pure Ni and Ni-

reducing oxidizing reducing eff

electrical conductivity atmosphere atmosphere atmosphere containing oxides play a crucial role in the observed electrical conductivity changes. This pro- time vides explanations for the often observed strong Fig. 2: Electrical conductivity variation based on speciﬁc mi- effect of redox-cycles on the degradation behavior crostructure changes during heat exposure under different of SOFC-stacks. atmospheres in Nickel containing Cr2O3 layers. Literature: It turns out that overall electrical conductivity varies [1] M. Linder, T. Hocker, L. Holzer, O. Pecho, by several orders of magnitude and depends on K. ,A. Friedrich, T. Morawietz, R. Hiesgen, R. Kon- both the extrinsic electrical conductivities of the tic, B. Iwanschitz, A. Mai, J. ,A. Schuler, Solid State present phases as well as on their sizes, shapes Ionics, 283, 38–51, 2015.

Zürcher Fachhochschule 13 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.10 New generation of high-performance air heaters

The controlled heating of air ﬂows plays a big role in a number of industrial processes. Leister Technologies AG, Kaegiswil, is the world leader in plastic welding and process air equipment that relies on the efﬁcient and reliable supply of heated air. In collaboration with D. Penner’s team at IMPE and G. Boiger’s team at ICP, this project explores new manufacturing and design routes to develop a new generation of high-performance air heaters for application in future Leister products.

Contributors: T. Hocker Partners: G. Boiger, D. Penner (IMPE), Leister Technologies AG Funding: CTI Duration: 2015–2017

Recent advances in the development of new ma- Fig. 2 shows typical temperature (left) and cur- terials and manufacturing methods with potential rent density (right) distributions within such an air applications to air heaters provide a large potential heater. Brighter colors indicate higher values of for improving the heater performance at reduced both temperature and current density. manufacturing costs. However, while the choice of temperatures electrical current densities potential materials and designs is large, optimizing derived products purely by trial and error would be an almost impossible task due to the large number of selectable parameters. Instead, it is much more efficient to develop computer models that provide a basic understanding of the physical phenomena taking place and allow one to run extensive parameter studies. Fig. 2: Typical temperature and current density distributions in an air heater with heated walls. As an example, a electro-thermo-fluidic model has been implemented in our in-house FE-tool Seses. Since the electrical contacts have been assumed It approximated an air heater with electrically con- to lie at the border, this creates an inhomogeneous ducting walls, made e. g. from silicon carbide. The distribution of the electrical current and hence a in- model takes into account the flow of electrical cur- homogeneous temperature distribution. rent through the walls which, depending on the de- Fig. 3 compares the air outlet temperatures of dif- sign of the electrical contacts, might be rather in- ferent heater designs with each other for differ- homogeneous. ent heating powers. As expected, the air outlet temperatures increases almost linearly with heating power indicating that in theses cases the heat losses to the surroundings are small. However, the outlet temperatures vary quite significantly between the different designs and are significantly lower that the theoretical maximum outlet temperature for a given heating power. comparison of outlet temperatures 900 225 cha 70 mm 225 cha 40 mm 800 81 cha 70 mm theoretical 81 cha 40 mm 700 max. temp Fig. 1: Fully parameterized geometry of air heater model 600 implemented in our in-house multi-physics FE-codeSeses. 500

T (C) 400 The model then calculates the corresponding 300 Joule’s heat and how it is transferred to both the air 200 and the surroundings through heat losses. Fig. 1 100 shows typical geometries of such a model. The 0 0 500 1000 1500 2000 2500 geometry has been fully parameterized in order to Pel (W) efﬁciently investigate a large variety of different de- Fig. 3: Air outlet temperatures versus heating power for dif- signs. ferent air heater designs. www.zhaw.ch 14 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.11 Numerical Simulation of Stacked OLEDs and Solar Cells

In this project we investigate charge transport across organic-organic interfaces in organic semiconductor devices such as OLEDs and solar cells. In the framework of a 1D drift- diffusion model a prototype interface model for stacked devices is implemented and analyzed.

Contributors: E. Knapp, B. Ruhstaller Partners: Funding: SNSF Duration: 2014–2016

OLEDs consist of multiple layers of organic semi- voltage characteristics as the tandem device with conductor materials deposited on top of each the interface model (green circles). This prototype other. The use of different layers allows to bal- interface is an important step towards reaching the ance charge transport and optimize optical prop- long-term goal of simulating tandem devices and erties which thus leads to an improved device per- will also allow the study of tandem solar cells in formance. Taking this concept one step further which multiple units with different light absorption leads to tandem devices where multiple electrolu- properties are stacked. minescent (OLED) units are vertically stacked and connected by a interconnector layer, which serves as a charge generation layer. Such tandem devices show an enhanced light emission as multiple photons can be emitted for each injected electron- hole pair thanks to the charge generation layer, see Fig. 1.

Fig. 1: A single unit OLED is shown on the left whereas on the right side two units are stacked leading to a tandem device which has a higher current efﬁciency and luminance.

The enhanced current efﬁciency and luminance at low current densities and enhanced lifetime for tandem devices makes them very attractive for applications. In this project a thermodynamic hopping model as proposed by S. Altazin (Fluxim AG) is translated to an interface condition within the 1D drift-diffusion framework. With this prototype we are able to analyze different interface conﬁgura- tions depending on the energy level of the HOMO and LUMO of the individual layers. In Fig. 2 we compare the simulation of a single unit (blue) with a tandem device (green circles) as illustrated in the Fig. 2: The current-voltage curve of a single OLED unit is shown as the blue dotted line. The tandem device is once legend above the graph. Two single units in series modelled as two single units in series (black line) and with are drawn in black and show the same current- the interface model as the entire cell.

Zürcher Fachhochschule 15 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.12 LED-based sun simulator for solar cell characterization

Artiﬁcial light sources, which are used for performance characterization of photovoltaic cells, should spectrally, spatially and temporally match the natural sunlight as close as possible for reliable measurements. We have designed and built a sun simulator based on high-power LEDs, which can be matched to the sun spectrum in the range of 400–750 nm within the spectral A+ class and is compact enough to be integrated into the commercial solar-cell characterization system of our industrial partner.

Contributors: M. Jazbinsek, M. Krajewski, K. Pernstich, B. Ruhstaller Partners: Fluxim AG Funding: KTI Duration: 2013–2015

Recent advances in high-power light-emitting Fig. 1 shows a possible spectrum of the first ver- diode (LED) technology have enabled the use of sion of our simulator, using various-color LEDs LEDs for solar simulators with many advantages ranging from 440 nm to 730 nm peak wavelength. over traditional xenon and metal halide lamps, The wavelength range can be straightforwardly ex- such as long lifetime, much lower price, flexibil- tended using compact LEDs emitting deeper in ul- ity to match and fine-tune a desired spectrum and traviolet and further in the infrared range. modulate it in real time, and LEDs are addition- For reliable solar cell characterization, light com- ally more environmentally friendly. Within the CTI ing from different LEDs should be homogeneously project PAIOS+ we are developing a sun simulator distributed at the place of the sample, so that both implementing 16 LEDs to match the sun spectrum light intensity and its spectral distribution are uni- or another desired spectrum, as close as possible. form across the sample. To achieve a high homo- The electronics is designed in a way that each of geneity we implemented special light-mixing op- the LEDs can be driven individually. The software tical elements that homogenize the initially non- control of the electronics will also enable real-time uniform LED sources; a detail is shown in Fig. 2. monitoring and fine adjustment of the spectrum. Our home-built sun simulator is very compact, with a footprint of the 16 LEDs of less than 2 cm2, to be later on easily integrated in photovoltaic- measurement set-ups.

Fig. 2: Detail of the spatial mixing of different-color LEDs (shown for 3 out of 16 LEDs), which is achieved using special light-mixing optics (ZEMAX simulation).

Our future work will concentrate on the optimization of the software control, complete optical characterization of the sun simulator under working

Fig. 1: Sun spectrum (AM1.5g) and a calculated sun simu- conditions and extension of the emmiting wave- lator spectrum from our multi-LED solar simulator. length range.

www.zhaw.ch 16 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.13 Impact of sand content on solute diffusion in Opalinus Clay

Low-permeability clay rock formations are considered as potential hosts for radioactive waste. Clay rocks typically have a very low hydraulic conductivity and the transfer of radionuclides will be largely controlled by diffusion. Diffusion depends strongly on geometric parameters, which in turn are intimately related to the microstructure. The impact of non- porous sand grains on diffusion was investigated by using synchotron X-ray computed microtomography in combination with diffusion simulations.

Contributors: L. Keller Partners: Funding: Nagra Duration: 2015–2016

Low-permeability clay rock formations are con- diffusion at larger scales. In a first step a set of sidered as potential hosts for radioactive waste. different clay matrix mesostructures were recon- Clay rocks typically have a very low hydraulic con- structed on the base of synchotron X-ray com- ductivity and the transfer of radionuclides will be puted microtomography applied to clay rock sam- largely controlled by diffusion. Diffusion depends ples from northern Switzerland, e.g. Opalinus Clay strongly on geometric parameters, which in turn see Fig. 1. In a second step mesostructural effects are intimately related to the microstructure. The on diffusion were quantified by applying diffusion mesostructure (micro to millimeter scale) of clay simulations to reconstructed mesostructures. Fur- rocks was considered as two-component mixture ther analysis revealed that contrictivity is the most consisting of impermeable non-clayey sand grains dominant parameter, which controls diffusion on embedded in a permeable clay matrix. Provided the millimeter scale in Opalinus Clay. Regarding that representative diffusion properties can be de- diffusion, the mesostructure of the clay matrix is fined, the clay matrix can be treated as a contin- near isotropic. Hence, the reason for anisotropic uum. Under these conditions diffusion at larger diffusion in Opalinus Clay must be searched on scales will depend on geometric properties of the the nanometer to micrometer scale and there is mesostructure. The objective of this study, then, caused by anisotropic pore path tortuosity related is to analyze geometric parameters, which control to shape preferred orientation of clay platelets.

Fig. 1: a) Reconstructed microstructures of clay matrix (rows) of the analyzed sample (columns). XCT refers to the analyzed volume. b) Diffusion simulations: the colors represent normalized concentrations within the clay matrix in case diffusion occurs in x-direction. The calculations yielded the ratio De/Dm, where De is the effective bulk diffusion coefficient and Dm is the isotropic bulk diffusion coefficient of the clay matrix in absence of a non-clay material. According to the theory of diffusion in porous media, the relation between De and Dm may be given by De=fGDm, where f is the clay matrix content and G is the geometric factor that accounts for microstructural effects on diffusion. c) Geometric factor versus clay matrix content. Black squares were determined on the base of diffusion modelling and the black line is a fit to these data.

Zürcher Fachhochschule 17 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.14 Fast transient simulation of semiconductor devices

An implicit adaptive solver was developed at the ICP, which allows for the fast simulation of time-dependent charge transport in semiconductor devices. This solver is about 150 times faster than a previously used explicit solver. It has been partially incorporated in the latest version 4.3 of the OLED and organic solar cell simulation software Setfos by Fluxim AG.

Contributors: C. Kirsch, S. Altazin, A. Stous, B. Ruhstaller Partners: Fluxim AG Funding: CTI Duration: 2013–2015

The transient response of semiconductor de- designed to be unconditionally stable, such that vices to various changes from equilibrium is re- the full range of time step sizes may be used in the quired for several characterization techniques, simulation with no risk of non-physical solutions. such as photo-CELIV, transient photovoltage, tran- For these solvers, the time step size is limited by sient photocurrent, transient electroluminescence, the accuracy condition only, and thus the compu- and dark injection transient measurements. Mea- tation time for the simulation may be much shorter. surement data can be used to estimate mathemati- An implicit transient solver was developed at the cal model parameters. For a typical parameter es- ICP within this CTI project. It has been imple- timation based on curve fitting multiple numerical mented by Fluxim software engineers and is avail- simulations of the transient response need to be able in the latest Setfos version 4.3. carried out. Therefore, efficient parameter estima- During the numerical simulation of transient phe- tion requires fast device simulations. Due to their nomena the relationship between accuracy and conditional stability the explicit transient solvers time step size (blue line in Fig. 1) often changes available in previous Setfos versions converged over time. Abrupt changes from equilibrium, for only for relatively small time steps. A large number example, may require very small time steps in or- of time steps was thus necessary for these solvers der to resolve the transient response of the device. to reach the prescribed simulation end time, which On the other hand, much larger time steps may be led to a long computation time. This disadvantage used when the device is close to equilibrium. A of conditionally stable solvers is illustrated in Fig. 1. variable time step size is commonly employed to ensure that the accuracy criterion is satisfied at all stable unstable range of time step sizes times while the computation time is minimized. unavailable to accuracy explicit solvers

computation time prescribed minimum accuracy

time step size Fig. 1: The stability condition for explicit transient solvers may severely limit the time step size used in simulations. Fig. 2: The time step size as chosen by the adaptive time- stepping scheme, vs. time, for explicit and implicit solvers. The blue line shows how both the accuracy and the The inset ﬁgure shows a zoom of the region around 10−5 s. computation time increase with decreasing time The time step size vs. time is shown in Fig. 2 for a step size. For a prescribed minimum accuracy test problem in which the applied voltage changes (black dashed line) a certain time step size must abruptly initially and again after 10−5 s. The adap- not be exceeded. However, the stability criterion tive time-stepping scheme varies the time step size for explicit transient solvers often imposes a more accordingly over several orders of magnitude. For severe restriction: it requires the time step size to the explicit solver it is limited to about 2 × 10−11 s be located inside the stable region, otherwise non- because of the stability condition, whereas the unphysical behavior of the numerical solution, such conditionally stable implicit solver may use much as oscillatory exponential growth, may occur. On larger time steps. In this test the implicit solver the other hand, implicit transient solvers can be was about 150 times faster than the explicit solver. www.zhaw.ch 18 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.15 CARDYN - Charge carrier dynamics in organic electronic devices

The correct description of charge carrier transport is crucial in the understanding of the physics of organic electronic devices such as organic light-emitting diodes (OLEDs) and organic solar cells (OSC). This project aims to improve existing models and develop new ones to describe the experimental data. SNF and DFG give joint funding for two PhD projects.

Contributors: S. Züﬂe, E. Knapp, M. Regnat, B. Ruhstaller Partners: Universität Augsburg Funding: SNF, DFG Duration: 2015–2017

The electric current in organic electronic devices tivation energy can be extracted. can be modeled with a drift-diffusion approach. In this project also novel hole injection materials Several physical processes have to be taken into are investigated, such as HATCN. Due to the po- account, like charge carrier injection and extrac- sition of the energy levels the injection mechanism tion, transport in disordered materials, charge car- is fundamentally different from other injection ma- rier recombination and trapping. In order to find terials. For this purpose a new interface model material parameters often monopolar devices are (Altazin-Model) is being developed with the asso- fabricated, where the material to investigate is ciated industrial partner Fluxim AG. It will be able sandwiched between two contacts. Choosing ap- to describe the hole injection from HATCN, but will propriate contact barriers ensures that only one also be of interest for interface layers in tandem charge carrier can flow through the device. The devices. measured IV-curves can then be used to extract With appropriate charge transport models and ef- the charge carrier mobility of this material, by fit- ficient numerical solvers we will be able to extract ting a space-charge limited current model. crucial device parameters such as charge injection In complete OLEDs or organic solar cells more parameters from a comparison of measured and layers are needed, in order to guide the charge simulated data. Thus, we pave the way to a non- fluxes. In OLEDs it is important to have a low invasive in-situ method for studying charge trans- injection barrier, which can be achieved by in- port in OLEDs and solar cells. jection layers. Most of the materials employed as electron transport layers are polar, they exhibit a sheet charge density at the layer interfaces. This charge affects the built-in field of the electrodes and leads to an enhanced hole injection. One way to measure these injected holes is impedance spectroscopy, which is sensitive to the mobile charges in the device. In this case two plateaus in the capacitance are observed in the different operating ranges. As injection is always a strongly temperature-dependent process, a temperature variation leads to a shift of the transition Fig. 1: Capacitance-frequency plot at varied temperatures frequency between the two plateaus. From an Ar- (C-f-T). The shift of the transition frequency shows Arrhenius rhenius analysis of the transition frequency the ac- activation.

Zürcher Fachhochschule 19 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.16 Fluxim Research and Development Support

Not all the software the ICP creates during its R&D projects with Fluxim AG is easy to deploy after its successful completion. Fluxim as a spin-off and partner of the ICP helps to conserve the gained knowledge for the ICP and third parties and engages some ICP staff to assist in doing so.

Contributors: K. Lapagna, S. Züﬂe, B. Ruhstaller Partners: Fluxim AG Funding: Duration: 2014–

As an ICP spin-off, Fluxim is still closely collabo- and Development Support project. This includes rating with topic related groups of our institute. Big tasks like making the software more stable, more parts of this collaboration are based on synergy flexible, faster and most of all, more user friendly effects, where the ICP and Fluxim are contribut- and accessible. As an outcome, a lot of reusable ing to the same projects and are working towards software is made available in a more powerful and the same goals. The offices of Fluxim and the ICP convenient way. The ICP immediately profits from are closeby which gives the employees the free- this, as it can make use of this software in con- dom and flexibility to easily roam between the two secutive R&D projects, letting Fluxim take care sites and work side by side with their partners if the of the maintenance and fully concentrate on the situation calls for it. This leads to a more efficient new tasks at hand. With a symbiosis like this, exchange of information, quicker decision making less of the gained knowledge gets forgotten over and a more specific shared vision on how to ad- time or stays inaccessible in unmaintained private vance a common project. software archives. Recent examples of this R&D collaboration are the successful integration of Mie Most projects will produce a lot of new ideas, re- particle scattering, simulation of microtexture scat- fined physical models and bits and pieces of soft- tering topography data and the integration of simu- ware, that were used to create and gather the relations based on ray-tracing into Setfos. In addition sults that were necessary for the goals of these there is a lot of fine tuning, bug fixing and new sets ventures. Unfortunately, most of the resulting soft- of results and plots that are made available with ware is highly adapted to the use case that was the help of this joint effort. needed for a specific task, to answer a specific scientific question. It is often not usable for third parties or covers just parts of the full power of the underlying models. Fluxim, as a company that op- erates in the private sector, has a strategic interest in making knowledge, that was gathered during these projects, available to third party companies and other research units, outside the scope of the projects where the ICP directly participates. Thus, there is extra effort needed to polish, port and integrate the newly acquired knowledge and software pieces into the products of Fluxim. If ICP staff is involved in walking this extra mile, this effort is commissioned through the Fluxim Research Fig. 1: Visualization of a randomly generated microtexture.

www.zhaw.ch 20 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.17 Electrical interconnections in solar cells and modules

Thin ﬁlm solar cells and modules rely on transparent conductive oxides (TCO) to transport the generated current to external contacts. Since a few years a metallic mesh is used in combination with the TCO to improve the conductivity. At ICP numerical simulations are used to optimize the current collection by minimizing both electrical losses and optical losses due to absorption and shadowing in the TCO and mesh. Additionally, the size of the interconnected cells in large area modules is optimized to minimize the overall losses.

Contributors: P. Losio, B. Ruhstaller Partners: CSEM, EMPA, PV Lab-EPFL, LPI-EPFL Funding: Swiss Federal Ofﬁce for Energy, CCEM Duration: 2014–2017

Thin film photovoltaic modules can be manufac- tion of the trade-off between electrical losses and tured on large areas and laboratory results indi- light absorption losses. At ICP simulations are cate the possibility to obtain a good efficiency at done to optimize large area modules considering limited costs, however one of the main limitations all these aspects. An example based on a CIGS in transferring high performance laboratory solar cell is shown in Fig. 1, a wide range of TCO thick- cell to large area is related to electrical losses over nesses and cell widths were considered: the min- the large surfaces necessary for commercial de- imal achievable loss is 5.6%. The usable parame- vices. Transparent conductive oxide (TCO) layers ter space for TCO thickness and segment width are usually used to transport the generated cur- defining loss thresholds of 6%, 8% and 10% is rent, however the layer conductivity is usually or- shown in Fig. 1. ders of magnitude lower than in metals thus lead- The optimization of metallic meshes in combina- ing to ohmic losses. The conductivity of TCO lay- tion with TCO layers requires the use of a com- ers can be increased during manufacturing leading putationally efficient 2D+1D FEM approach to cor- usually to a loss of efficiency because part of the rectly model the voltage distribution across the cell light is absorbed in the TCO layer. In recent times, and the electrical losses as shown in Fig. 2. In the a fine metallic conductive mesh is added on top example the external contact is on the left edge; of the TCO surface to improve the conductivity at due to a poor conductivity of the TCO layer the the expense of a localized total loss of generated voltage is not uniform across the device. Ohmic current due to shadowing. losses indicated by the color scale are larger near the contacting electrodes due to a larger current 12 density. The FEM approach allows to optimize the Loss < 10% 10 Loss < 8% TCO thickness and the shape of the metallic mesh. Loss < 6% 8 Best cell width Best result, loss 5.6% [mm]

6 width

4 cell

0 0 200 400 600 800 1000 TCO thickness [nm]

Fig. 1: Parameter space for three power loss thresholds in CIGS solar modules. The parameters necessary for achiev- ing the lowest losses are marked by the red dot. The best cell width as a function of TCO thickness is marked by a green line. Fig. 2: Voltage distribution and ohmic losses on the top elec- Scaling solar cells to large area modules addition- trode of a 0.5 cm2 organic solar cell using a front TCO and ally requires to take into account the losses of ac- a metallic mesh, the external contact is at the left edge. The colorbar indicates the relative ohmic losses; the operating tive area necessary to accommodate the serial in- voltage is 0.64 V. The metallic contact shape is shown at the terconnection of solar cells and a careful optimiza- bottom.

Zürcher Fachhochschule 21 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.18 Rigorous simulation of light scattering

Light scattering plays an important role in the optimization of high performance solar cells, especially for hybrid tandem cells combining different solar cell technologies like perovskite solar cells, heterojunction Silicon solar cells and CIGS solar cells. Usually solar cells have a rough surface and often the typical size of structures on the surface is comparable with the light wavelength thus requiring a rigorous simulation to obtain reliable results. A combination of rigorous simulations and approximations allows to reduce the time necessary to complete a simulation.

Contributors: P. Losio, B. Ruhstaller Partners: CSEM, EMPA, PV Lab-EPFL, LPI-EPFL Funding: SNF Duration: 2015–2019

Light scattering plays an important role in the op- As an example, the intensity of scattered light timization of high performance solar cells: opti- above a rough Zinc oxide (ZnO) surface is shown mized light scattering allows to reduce the amount in Fig. 1, the numerical solution was computed us- of material needed and to improve the conversion ing the commercial software package JCMsuite. efficiency of solar cells. A current topic of research Hybrid solar cells have however a total thickness to achieve solar modules having 25-30% conver- of ≈ 300µm which is about two orders of mag- sion efficiency are hybrid tandem solar cells com- nitude larger than the rough surface features un- bining different solar cell technologies: usually a der consideration. A rigorous computation of the perovskite solar cell combined with either a hetero- whole cell structure is computationally very expen- junction Silicon solar cell or a CIGS thin film solar sive. An approach to reduce the total computation cell. time is being developed at ICP: the computation is split into a rigorous near field computation near the rough surfaces and a more efficient ray-based method for thick, homogeneous layers.

Fig. 1: Representation of the scattered light intensity above Fig. 2: Propagating modes scattered by a rough ZnO sur- a rough ZnO surface, λ = 600nm, side length 4.5µm. face texture represented as vectors.

These three types of solar cells usually have a To this purpose the propagating modes are ex- rough surface and the typical size of structures tracted from the FEM near ﬁeld solution and can on the surface is comparable with the light wave- be used with other simulation tools as shown in length. A reliable simulation of this situation re- Fig. 2. All incidence angles from both sides quires a rigorous approach based on numerically of the rough interface are considered to compute solving Maxwell’s equations using the ﬁnite ele- the complete Bidirectional Scattering Distribution ments method (FEM). Function (BSDF) matrix entries.

www.zhaw.ch 22 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.19 Simulation of heat transfer processes within a fuel cell system based on OpenFoam

A versatile, fully modifiable, finite volume, thermo-fluid-dynamic model of a SOFC system, has been created based on OpenFoam. This flow- and heat transfer model takes the level of physical detail beyond that of previously known simulation methods.

Contributors: G. Boiger, J. Fuchs, C. Meier, V. Lam Partners: Hexis AG Funding: Hexis AG Duration: 2014–2015

The model can support the limited temperature umetric heat sources. Thus common, interface measurement options inside a stack and will help based methods of implementing thermal radiation to gain a more detailed insight into overall ther- between solid objects will not work. The prob- mal conditions. Thus high temperature gradients lem has been overcome by modifying the solver, within the SOFC stack can be averted more effi- such that an additional fluid domain, connecting ciently in future system designs. This work focuses the stack to the interacting solid domains, could on the modeling of two major thermal aspects with be introduced. impact on the temperature distribution of a SOFC system: anisotropic heat conduction within a stack and thermal radiation effects. Because of the layer structure of the SOFC stack, heat conduction properties, orthogonal to these layers vary from those in radial direction. In our model, the implementation of layered stack geometry is based on one continuous, porous domain. In order to realize anisotropic heat conduction mechanism in this domain, the concept of thermal baffles is used. Ac- cording to OpenFoam, a thermal baffle has zero physical thickness in the flow domain, but non-zero thickness for thermal calculations. Representing the different layers in the actual structure, thermal baffles are introduced into the stack domain and act as a quasi-anisotropic axial thermal resistance. A model for considering relevant thermal radiation effects has been devised as well. The radiation calculation implementation in OpenFOAM [1] and Ansys CFX [2] focuses on the fluid domain, separating interacting solids. This makes sense for most applications, where every solid do- Fig. 1: Side view of simulation results of the thermo-fluid- main has an interface with the fluid domain. In dynamic model of a SOFC system. our case though, the stack domain is represented as porous solid, located within the fluid domain Literature: without defined stack-fluid interface. Energy cou- [1] http://OpenFOAM.org. pling between the two phases is realized by vol- [2] Ansys CFX Solver Modeling Guide, 2013.

Zürcher Fachhochschule 23 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.20 Tentative modelling of the failure in Solid Oxide Fuel Cell

The thermo-mechanical failure of the interconnect components in Solid Oxide Fuel Cell SOFC is investigated based on efﬁcient numerical models and in the light of the opera- tional observations. Varied methods based on continuum and discontinuum approaches are examined, in the former the damage model is considered with both local and non-local formulations. In the later, the fracture mechanics is analyzed with the application of both XFEM and cohesive element methods. The developed approach present an advanced pre- dictive tool to be exploited in a reliable design of SOFC stack.

Contributors: Y. Safa, T. Hocker Partners: Hexis AG, NM Numerical Modelling GmbH Funding: Swiss Federal Ofﬁce of Energy Duration: 2015–2017

Solid Oxide Fuel Cell SOFC system developed eXtended Finite Element Method, Fig. 1c. This to by Hexis AG, Winterthur-Switzerland presents a represent stress singularity at the crack tip as well promising heat and power source based on the as the discontinuous displacement on the crack chemical energy of natural gas. Operated at boundary. A numerical estimation of stress inten- high temperature, the interconnect components of sity factor is obtained with different methods, like SOFC, exhibit some damage. Therefor, the control for example, the application of J-integral. However, of the thermo-mechanical failure in the intercon- due to limited-implementation capability of XFEM nect parts is highly required for the structural in- to capture the crack branching and fragmentation, tegrity of the designed system, and hence, its long cohesive-zone model is applied. This allows to service life. Although that operated system may avoid singular and rather unphysical behavior of survive the onset of some stable cracks in the cell, the stress on the crack tip. the unstable crack propagation lead to fuel leak- Finally, a realistic perspective of this work is to age and power losses. Hence, the identiﬁcation achieve an interaction between a local micro scale of the typical failure modes from the fractography simulation in local parts and the macro scale anal- observations of the failed cells present an initial in- ysis of the stress in the global domain obtained by vestigation step, like for instance, observation of SESES Finite Element Code. propagated cracks in radial and tangential direction in the coating layers on anode and cathode sides in postmortem cells. Later, the analysis of fracture mechanics of the components would be a highly relevant topic in a complementary needed step for a reliable design guideline of the stack. The goal of this work is to provide a numerical pre- dictive tool of the fracture toughness, crack propagation and damage evolution in the cells in order to develop a primary failure criteria. This is to serve in the structural design of the stack, the material selection and the optimization against thermome- chanical failure of the interconnect parts. A continuum approach based on the damage evolution is used to represent the crack where material defects are initially considered with a random values of the damage energy threshold, Fig. 1a. To avoid inconsistent localization of damaged zone, a non-local damage formulation is used to represent a realistic damage propagation, Fig. 1b. Since the damage model doesn’t represent the interaction of Fig. 1: Failure models in a quarter part of electrode. Figs. (a), (b) and (d) are the results of the simulation using the crack faces (contact and friction), a discontinu- AKANTU package, Fig. (c) is obtained using the GETFEM ous approach is used with the application of XFEM package. www.zhaw.ch 24 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.21 A model-based optimization of cooling tunnel processes

A model describing the crystallization of a melt sample exposed to the wind flow in a cooling tunnel has been implemented. The effects of the heat transfer and the interconversion between melt phase and crystal polymorphism were analyzed. A new enthalpy-formulated coupling between the phase kinetics and the Stefan problem was introduced. The flow characteristics and the heat transfer mechanisms along the circumference of the cylindri- cal sample were considered with separate contributions on the front and rear parts of the sample and turn to have a clear influence on the cocoa butter crystal distribution. The numerical results for the temperature distribution within the sample are in agreement with measurements.

Contributors: Y. Safa, T. Hocker Partners: IFNH-ETHZ and several industrial partners Funding: CTI Duration: 2013–2016

The matured know-how of the thermal processing a minimum value at θ = 85 due to the increase of of the manufactured solids from its melt is one of the thermal resistance with boundary layer growth. the key issues for the high quality-control in the The numerical results of the crystal fractions are production line of these materials. Beside the cool- in agreement with NMR measurements and the ing rate and the distributed heat flux, the solidifica- obtained temperature values fit those of the T- tion process can be influenced by kinetic effects sensors inside and around the sample. and then, several polymorph constitutions arise in the processed sample. This is due to the mass diffusion between adjacent phases, the metastable forms that can exist or coexist in the presence of more stable forms. However, the quality of the product and the endurance of its desired properties that are designed for some specific applications can be affected by the crystal behaviour, like for instance, the instability of certain crystals, the interconversion between crystal phases and the transition between crystals and melt phase. Since material processing undergoes often a ther- Fig. 1: Temperature on the downwind point of the sample mal history, like cooling from a high temperature, after 150 minutes of cooling tunnel operation. that should be managed through either the optimized mould geometry or the controlled cooling tunnel parameters. A computational model describing energy transfer coupled with mass transformation between crystal phases in chocolate was developed at ICP in a collaborative research work with IFNH-ETHZ and some other industrial partners. This model allows one to predict the temperature and the crystal evolutions, see Fig. 1-2 and the corresponding changes in the properties through processes like cold moulding, tempering and seeding. Based on an analytical approach introduced by Sanitja and Goldstein (2004), the implemented convective flow exhibits an increase of the heat transfer around the sample with turbulence intensity. On the other Fig. 2: Evolution of stable crystal upon cooling at 65 min- hand, the relatively high Nusselt numbers at the utes. High thermal conductivity of aluminum shell allows a front stagnation points decline gradually to reach symmetric crystallization.

Zürcher Fachhochschule 25 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.22 Simulation Software for DSSC Modules

PECSIM is a simulation software developed at ICP for the analysis and optimization of dye- sensitized solar cells (DSSCs). In collaboration with our industrial partner it is extended by a new toolbox for the simulation of large-scale modules and used to develop optimization strategies for their solar panels.

Contributors: M. Schmid, D. Bernhardsgrütter, J. Schumacher Partners: Glass2Energy SA, CSEM Alpnach, HEIG-VD, ISAAC-SUPSI Funding: CTI Duration: 2015–2016

The technology of DSSCs has been established in the 1990s at EPFL and is now on the brink of commercialization. It has a variety of advantages as e.g. transparency, exploitation of diffuse light and low production costs. These attractive features make them well suited for building-integrated photovoltaics (BIPV). Among the biggest challenges are long-term stability and the relatively low efficiency of DSSC modules. Our industrial partner Glass2Energy produces DSSC panels for the BIPV market. Their modules Fig. 2: Qualitative comparison of the simulated power out- not only produce energy but also take the functions put of modules with optimal matched currents (Module 1) versus modules with bad matched currents of the individual of façade, windows and decorations, see Fig. 1. cells (Module 2). Glass2Energy addressed stability issues by estab- For a given configuration of the individual cells and lishing the industrial manufacutre of glass sealing. a given module size, an optimization of the mod- With help of the PECSIM simulation software the ule geometry is feasible. For an ideal choice of power output of their product is improved. the cellwidth ratio the currents of the back- and frontside oriented cells are matched, see Fig. 2. Additionally, variation of the cellsize entails two op- posing effects on the module efficiency. It affects the power loss due to charge transport in the transparent conducting oxide as well as the dead area due to glass sealing. An equilibration of these losses leads to an optimal cellsize. Fig. 1: Transparent coloured photovoltaic cells manufac- In summary, we have an extended version of PEC- tured by glass2energy presented at the universal exhibition SIM at disposal which is ready to use for analy- Expo Milano 2015. sis and optimization of DSSC modules produced In order to build efficient DSSC modules it is nec- by Glass2Energy. We are currently working on essary to optimize the series connection of the in- the validation of our simulation model. As a next dividual cells. For this purpose, a new simulation step in the ongoing project we target a statistical mode is implemented into the PECSIM software. analysis of the most relevant parameters. Perfor- It allows to investigate the DSSC module output mance distributions are then calculated as a func- for varying composition of the individual cells and tion of fabrication parameter distributions. In fu- module geometries. A quantitative loss analysis ture this could eventually be incorporated into an reveals the energy losses within each cell as well inline quality control system via statistical process as efficiency losses due to upscaling from small control based on the electrical performance of the cells to modules. products.

www.zhaw.ch 26 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.23 Coulometric system with generator cell

An automatic Coulometric measurement system for titration is developed. The system is based on a compact and easy-to-use cartridge system. The physical and chemical processes are summarized in a simulation model allowing for numerical electrochemical impedance spectroscopy.

Contributors: G. Sartoris, L. Holzer Partners: Mettler-Toledo AG, ZPP, IMPE, ICBC Funding: KTI Duration: 2014–2016

This project aims at developing an automatic, com- this bipolar model computed with actual parame- pact and easy-to-use measurement system for ters, the impedance spectra for both carriers can- titration based on a cartridge system delivering the not be evaluated, due to the adverse numerical reagent and controlled by hardware. At ICP,we are condition caused by the very thin boundary layers −10 concerned with the modeling and optimization of of thickness ≈ 2×10 m. the generator cell. If during the first year, we were After these first numerical investigations, we ar- mainly concerned with geometric optimization, in rived at the conclusion that a full fledged numerical the second one, we focused our attention on har- model may not help to improve our understanding monic analysis by computing impedance spectra of the titration cell. Degradation effects influencing as a tool for model validation. the contact surface charge are expected to have Let us assume we want to titrate an acid and there- a major impact on the high-frequency peak, but fore at the working electrode (WE), we generate this peak is out-of-measurability. If present, from OH− hydroxide ions and at the zinc counter elec- measurements one can clearly identify the middle- trode (CE), we generate Zn+ ions. Between the frequency peak caused by the external double- analyte and the cartridge half-cell, there is an ion layer, but this peak is merely an input parameter selective membrane which ideally should block all and not a real outcome of our numerical model. At OH− and Zn+ ions and just allows passing some the end, one can just compare the measured and other anions A− from the analyte to the cartridge computed low-frequency diffusion range, however, half-cell. So in the cartridge half-cell we have an even here we have a very adverse numerical situa- in-flow current of Zn+ ions at the CE and in-flow tion due to a fluid phase with large ions concentra- current of A− at the membrane, but otherwise no tions and large dimensions. However, we note that other flow takes place over the boundary of the there are examples where numerical impedance cartridge half-cell. For this model, the transport spectroscopy has been successfully applied, like model is therefore given by the diffusion and mi- for PEM fuel cells. gration of positive and negative charged carriers combined with the Poisson’s equation determining the electric potential. Non-resistive impedance spectra are caused by accumulation of charged carriers and for a titration cell these effects are taking place at inhomogeneous material interfaces, hence of primary importance is the form of the current injection at the electrical contacts. As an example Fig. 1 shows the Nyquist plot computed for a single carrier and some non-ideal current injection. The high frequency peak at 20 GHz is caused by the charged boundary layer acting as a capacitor and it is pretty invariant with respect to changing the domain’s size. The low frequency peak at 600 Hz is due to Fig. 1: Contribution to the Nyquist plot for a single carrier charge transport within the domain. However, for and a non-ideal contact.

Zürcher Fachhochschule 27 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.24 Euler-Lagrangian model of particle laden ﬂows and deposition effects in powder coating

In order to study the powder coating process of metal substrates, new means of process- characterization have been devised and a comprehensive, numerical 3D Eulerian-Lagrangian model has been developed and qualitatively validated.

Contributors: G. Boiger, N. Reinke, S. Weilenmann, S. Hauri Partners: J. Wagner AG Funding: KTI Duration: 2015–2016

The powder coating process is widely spread and simple coating experiment on a small metallic plate commonly used in industry. However, knowl- within our experimental coating chamber, as seen edge about detailed phenomena and concern- in Figure 2, and applications of our model on vir- ing parameter-effect relations remains of predom- tual recreations of the same procedure. inantly empirical nature. To create the foundation for future knowledge-based improvement ef- forts of the coating process, the ICP has developed numerical models and characterization methods concerning particle motion and deposition effects within ﬂow- and electro-static ﬁelds.

Fig. 2: Coating pistol, coating chamber and on-going coating procedure of a metal plate.

Fig. 1: Triangle chart of coating particle cloud state for three different parameter set-ups (red, green, blue curve) and various particle size classes (dots).

By comparing the dimensionless effects of acting gravity-, electro-static- and fluid- drag forces on particle motion, we were able to propose a Fig. 3: Comparison of relative coating thickness measurements and corresponding simulations of the plate coating new kind of characteristic triangle-chart notation process. as seen in Figure 1. An extensive, dynamic, Euler-Lagrange model of the coating procedure Comparison of measured and simulated coating has been created as well. The model has been layer thicknesses, as seen in Figure 3, have shown implemented in C++ within the open source CFD a high degree of qualitative correspondence and platform OpenFOAM, is transient in nature with have thus helped to validate the numerical model. respect to the applied LaGrangian particle imple- Literature: mentation and the electro-static field calculation G. Boiger, Eulerian-LaGrangian model of particle- and is stationary regarding fluid-dynamic phenom- laden flows and deposition effects in electro-static ena. We have conducted comparisons between a fields based on OpenFOAM, to be published.

www.zhaw.ch 28 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.25 Simulation von Heizelementen für Heissluftgebläse

In Heissluftgebläsen werden bis anhin Heizspiralen zur Erhitzung der Luftströmung genutzt. Für derartige Anwendungen soll ein optimiertes Verfahren entwickelt werden, um die Strö- mung efﬁzienter aufzuheizen. Bevor jedoch eine Optimierung vorgenommen werden kann, müssen alle Parameter und Einﬂussfaktoren dieses multiphysikalischen Problems untersucht und verstanden werden.

Contributors: M. Boldrini, G. Boiger Partners: Leister Funding: KTI, Leister Duration: 2015–2017

Bei der Entwicklung neuer, optimierter Heizele- mung und den lokalen Eigenschaften des Fluides, mente für Heissluftgebläse ist es ausschlag- auf die Luft übertragen. gebend, dass die zugrundeliegenden physikalischen Vorgänge genau analysiert werden. Hierfür wurde ein 3D OpenFOAM Modell erstellt. Dieses soll die reale Geometrie eines einzelnen Heizkanals repräsentieren.

Abb. 2: Wall Heat Flux und Geschwindigkeiten.

Abb. 1: Schnitt durch Fluid Region. Mit dem Modell konnten alle physikalischen Ein- Wir haben uns für den stationären, einphasigen, flussfaktoren auf den Heizvorgang des Fluides un- laminar-/turbulenten Wärmeübergangssolver cht- tersucht werden. Auch war es möglich den Tempe- MultiRegionSimpleFoam entschieden. Damit war raturverlauf innerhalb der Heizspirale zu untersu- es möglich, ein Modell zu entwickeln, welches so- chen. Damit konnte gezeigt werden, welche Regio- wohl die Strömung der Luft, als auch das Hei- nen in Bezug auf den thermischen Energieüber- zelement selbst auflöst. Über verschiedene Ent- gang am effektivsten sind. wicklungsschritte wurde zuletzt die reale Geome- In einem weiteren Schritt wird es nun nötig, die trie eines Heizkanals relativ detailliert nachgebil- physikalischen Eigenschaften des Fluides und des det, Abb. 1. Hierbei wird Luft, als kompressibles Heizelementes genauer zu spezifizieren. Ausser- Fluid durch einen Überdruck in das Simulationsge- dem muss untersucht werden, ob der Einsatz ei- biet eingeströmt. Innerhalb des Simulationsgebie- nes Turbulenzmodells nötig ist. tes umströmt diese die Heizspirale im laminaren Literatur: Regime. Die Heizspirale selbst wird als Festkörper H. G. Weller, G. Tabor, H. Jasak, C. Fureby, A ten- simuliert, in welchem eine volums-spezifische, ho- sorial approach to computational continuum me- mogene Energiefreisetzung vorgegeben wird. Die- chanics using object-oriented techniques, Compu- se thermische Energie wird abhängig von der Strö- ters in Physics, 12, 6, 1998.

Zürcher Fachhochschule 29 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.26 Optimierung von porösen Diaphragmen Modell- und si- mulationsunterstützte Materialentwicklung

Für eine pH-Messelektrode soll ein leistungsoptimiertes, keramisches Diaphragma entwickelt werden. Um die Zusammenhänge der physikalischen Einﬂüsse auf die Diaphragma- leistung besser zu verstehen und somit gezielt bestimmte Eigenschaften des Materials optimieren zu können, wird die vom IMPE durchgeführte Materialentwicklung durch Modell- rechnungen von der Seite des ICP unterstützt.

Contributors: G. Boiger, T. Ott Partners: Mettler-Toledo, IMPE Funding: KTI Duration: 2014–2016

Die Leistung des Diaphragmas einer pH- zahlreichen Material- und Prozessparametern ab- Messelektrode hängt erheblich von folgenden hängt. Zur Bestimmung der Einflussstärken der Haupteigenschaften ab: elektrische Leitfähigkeit Parameter auf die Optimierungskriterien wurde in sowie Ausflussgeschwindigkeit und –rate des der Open Source CFD-Software OpenFOAM ei- Elektrolyten. Die Strömung und Leitfähigkeit des ne Parameterstudie an vereinfachten Geometrien Diaphragmas wurden in einem semianalytischen (Rohr mit Bottleneck) durchgeführt. Variiert wur- Modell beschrieben, damit die Einflüsse der ein- den die Länge und der Durchmesser des Bottlen- zelnen Parameter auf die Optimierungskriterien eck, der Skalierungsfaktor der Geometrie sowie untersucht werden können. die Druckdifferenz über die Probe und die Viskosi- tät des Elektrolyten. Mit Hilfe dieser Studie konnte die optimale Porenform bestimmt werden. Paral- lel zur Parameterstudie wurde aus den CT-Daten einer realen Probe eine Simulationsgeometrie erstellt deren Resultate durch Messresultate validiert werden konnte.

Abb. 1: Im Improvement Space wird eine Materialprobe mit einer Referenzprobe verglichen.

Abb. 2: gezielte Materialoptimierung.

Die Optimierung kann auf verschiedene Weise erreicht werden, da die Gesamtleistung Ω von Abb. 3: Porengeometrie einer realen Probe.

www.zhaw.ch 30 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.27 Simulation des Nano-Dosierverhaltens von nicht-Newton- schen Flüssigkeiten

In der Pharmaindustrie ist es häuﬁg notwendig Wirkstoffe im Nanoliterbereich zu dosieren. Da sich das experimentelle Studium des Dosierverhaltens solch geringer Mengen extrem schwierig gestaltet, wurde ein Modell erstellt, welches den Dosiervorgang simuliert. Bis anhin hat man sich auf newtonsche Fluide beschränkt. Das Modell wurde nun auf nicht- newtosche Fluide erweitert.

Contributors: M. Boldrini, S. Zangerl, G. Boiger Partners: Novartis Funding: ICP Duration: 2013–2016

Es wurde untersucht, wie man das nicht- decken zu können. Dem Modell sollten die Visko- newtonsche Dosierverhalten von Fluiden, welche sitätsmessungen, welche bis zu einer Scherrate in der Pharmaindustrie dosiert werden müssen, von 104 s−1 durchgeführt werden konnten, und die durch ein Modell abbilden kann. Zu Beginn wur- Extrapolation nach Sisko zugrunde liegen. Hier- den die nicht-newtonschen Modelleansätze, wel- für wurde ein mehrteiliger Ansatz entwickelt. Die- che in OpenFOAM bereits implementiert sind auf ser besteht einerseits aus einer Approximations- ihre Eignung geprüft. Zunächst wurde das Bird- funktion welche nach einem 5-Parameter-Modell Carreau Modell als vielversprechender Ansatz ein- an die Messkurve angenähert wird, sowie anderer- gestuft. Jedoch musste man feststellen, dass die- seits aus einer Extrapolationsfunktion nach Sisko, ses Modell nur für Fluide mit nicht extrem aus- um höhere Scherratenbereiche abzudecken. Zwi- geprägtem, nicht-newtonschen Verhalten geeignet schen den beiden Funktionen ist eine Blending- ist. funktion geschaltet, welche den Übergang dieser Funktionen regelt.

Abb. 2: Viskositätsverteilung innerhalb des Einströmbe- reichs der Dosiernadel.

Mit diesem Modell war es möglich, das Visko- sitätsverhalten aller gemessenen Fluide, zunächst Abb. 1: Viskositätsverhalten verschiedener gemessener qualitativ, nachzubilden. Hierdurch konnten auch nicht-newtonscher Fluide. die quantitativen Ergebnisse signiﬁkant verbessert Wie man in Abb. 1 erkennt, handelt es sich werden, jedoch musste man, aufgrund des gestie- bei den zu dosierenden Fluiden aber um solche, genen Rechenaufwands auf ein einphasiges Mo- welche ein teilweise extrem nicht-newtonsches dell umsteigen. Mit diesem Modell werden in ei- Verhalten aufweisen. Somit wurde es notwendig nem nächsten Schritt viele, weitere Fluide simu- ein eigenes Viskositätsmodell zu entwickeln, um liert und deren Dosierverhalten systematisch aus- den gesamten Viskositätsbereich der Fluide ab- gewertet.

Zürcher Fachhochschule 31 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.28 Nondestructive Quality and Process Control of Thermal Spray Coatings

Thermal spray coatings are used to increase resistance against mechanical, chemical and thermal wear. However, state-of-the-art testing methods cannot be used for continuous quality control during production. These methods are destructive, subjective and show low repeatability. In this project, a new method is developed for rapid, quantitative, nondestructive and repeatable in-situ measurement of porosity, thickness and thermal properties of thermal spray coatings. First results on samples from the industry partners show good correlation between the new and conventional methods.

Contributors: N. Reinke, A. Bariska, S. Hauri, T. Nguyen Partners: not disclosed Funding: KTI Duration: 2015–2016

Thermal testing of coatings is based on monitor- with High-Velocity Oxygen-Fuel (HVOF) process. ing dynamic heat diffusion on the surface of lay- The coatings are applied on piston rods, their ered media after excitation with a light source in main function is wear protection Low-alloyed car- a reﬂection setup. The heat diffusion process bon steel, sprayed with APS process on aluminum is, in addition to the thickness of the coating, af- cylinder bores. Their main function is to reduce fected by thermal properties of the coating. Thus, wear and lubricant usage. under certain conditions, it is conversely possi- In a previous project, we showed that it is possible ble to determine thermal properties of the coat- to simultaneously track changes in thickness and ings e.g. thermal coating resistance, thermal con- porosity using thermal testing of coatings. How- ductivity, thermal difffusivity, etc. as well as me- ever, this required an optical coupling medium, chanical properties that correlate with the thermal which is not acceptable for industrial application. properties, e.g. thickness and porosity. Thermal The main achievements of this new project are: spray coatings are available with a wide variety accurate physical models of thermal spray coat- of materials and applications processes. We fo- ings to compensate for the optical and infrared cus on the following thermal spray coatings in this semi-transparency robust and efﬁcient numerical project: Yttrium-stabilized zirconia, sprayed with algorithms to reliably extract information on poros- Atmospheric Plasma Spray (APS) process. These ity, thermal properties and coating thickness highly thermal barrier coatings are for example applied sensitive infrared detection system tuned to the in- to blades in gas turbines, their main function is frared properties of the coatings optimized excita- heat protection. Aluminum and chromium oxides, tion source, see Fig. 1. sprayed with High-Velocity Oxygen-Fuel (HVOF) process. The coatings are applied to steel sub- The results of comparing conventional lab analysis strates e.g. industrial rolls, their main function with thermal testing of coatings shows good corre- is wear protection. Tungsten carbides, sprayed lation.

Fig. 1: Comparison of porosity measurements on samples with conventional metallography versus thermal testing of coatings. The two methods correlate with R2 = 0.89. Thermal testing of coatings displays about three times smaller standard error than metallographic analysis. www.zhaw.ch 32 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.29 Pulverbeschichten mit Closed-Loop Regelung

Das ICP hat zusammen mit Industriepartnern eine neue Technologie entwickelt, die die Pul- verbeschichtung revolutionieren soll. Die Wagner-Geräte verfügen über eine hochgenaue Dosierungsautomatik, welche die Luftmenge zur Pulverförderung zu den Pulverpistolen permanent misst und regelt. Dadurch lassen sich dauerhaft konstante Werte sicherstellen. Aber, wie überprüft man verlässlich, dass diese Werte auch zur gewünschten Schichtdicke führen?

Contributors: A.Bariska, S.Hauri, B.Rutz, M.Torroni, B.Schmid, T.Nguyen, U.Vögeli, N.Reinke Partners: Winterthur Instruments AG, J. Wagner GmbH, Ronal AG, Ramseier Woodcoat AG Funding: KTI Duration: 2014–2015

Die Winterthur Instruments AG kennt schon lange pliziert und damit Material verschwendet. Auch das Bedürfnis ihrer Kunden, dauerhaft eine kon- das kann nicht mehr rückgängig gemacht werden. stante Sollschichtdicke in möglichst engen Tole- Zu dicke Beschichtungen werden allerdings häu- ranzgrenzen realisieren zu können. Denn bisher ﬁg in Kauf genommen, denn eine Unterbeschich- war eine konstante Schichtdicke, bei der weder zu tung, und damit mangelnde Qualität, soll auf je- viel noch zu wenig Beschichtungsmaterial aufge- den Fall verhindert werden. Diese Strategie führt tragen wurde, mehr oder weniger ein Zufallstreffer. dazu, dass zu hohe Materialkosten anfallen. Ein Bisher wurde die Schichtdicke nach dem Einbren- Rechenbeispiel mit Durchschnittswerten verdeut- nen manuell gemessen. Zwischen dem Auftragen licht, wie stark sich die Kosten für eine dauerhaf- der Beschichtung und dem Messvorgang können te Überbeschichtung aufsummieren bzw. wie viel allerdings einige Stunden vergehen, da der Pulver- Einsparpotenzial eine lückenlose Schichtdicken- lack vorher noch im Ofen eingebrannt wird und da- überwachung bietet. Um diese Einsparungen zu nach auf Raumtemperatur abkühlen muss, um das realisieren, braucht man allerdings ein Messsys- Messgerät beim Aufsetzen nicht zu beschädigen. tem, das vor dem Einbrennen am laufenden För- Wird dann beim Nachmessen einer Stichprobe ei- derband misst und das aufgrund der Messung vor ne Abweichung nach unten festgestellt, sind al- dem Einbrennen die Schichtdicken nach dem Ein- ler Wahrscheinlichkeit nach schon eine Reihe von brennen berechnen kann – den CoatMaster. Sind Bauteilen unterbeschichtet worden. Aufgrund der diese Voraussetzungen nun erfüllt, hat man einen stichprobenartigen Prüfung ist das Aufﬁnden der großen Schritt in die Zukunft der Pulverbeschich- fehlerhaft produzierten Teile schwierig und die tung ganz im Sinne der Industrie 4.0 gemacht: Es Nacharbeit mit viel Aufwand verbunden. Wird beim entsteht eine Pulverbeschichtungsanlage, die sich Nachmessen einer Stichprobe eine Abweichung selbst regelt. nach oben festgestellt, wird zu viel Pulver ap-

Fig. 1: Das Rechenbeispiel mit Durchschnittswerten verdeutlicht, wie viel Einsparpotenzial eine lückenlose Schichtdicken- überwachung bietet und was Beschichter in C pro Jahr sparen können. Der Berechnung liegen folgende Annahmen zugrunde: Pulverpreis = 5.00 C/kg, speziﬁsches Gewicht = 1.5 g/cm3.

Zürcher Fachhochschule 33 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.30 Qualitätssicherung von Haftvermittlerschichtdicken in der Produktion von Drehschwingungsdämpfern

Die Schichtdicke von Haftvermittlern liegt typischerweise zwischen 10µm und 20µm bei einem Einschichtsystem und zwischen 20 und 40µm bei einem System aus Primer und Cover. Bei Schichtdicken unterhalb dieses Toleranzfensters können Haftungsprobleme der Gummi-Metallverbindung auftreten und die Funktionsfähigkeit des Drehschwingungsdämp- fers nicht gewährleistet werden. Bei zu hohen Schichtdicken können unter mechanischer Belastung des Bauteils sogar Risse innerhalb der Haftvermittlerschicht auftreten. Die pro- duktionsbegleitende Schichtdickenmessung ist also ein wesentliches Qualitätskriterium zur Gewährleistung der Funktionstüchtigkeit von Drehschwingungsdämpfern.

Contributors: A.Bariska, S.Hauri, B.Rutz, M.Torroni, B.Schmid, T.Nguyen, U.Vögeli, N.Reinke Partners: Winterthur Instruments AG Funding: Winterthur Instruments AG Duration: 2014–2015

Radialschwingungen entstehen durch die stoß- Bei funktionskritischen Qualitätskenngrössen ist weise Kraftübertragung vom Kolben über Kol- eine kritische Beurteilung des verwendeten Prüf- benbolzen, Pleuelstange auf die Kurbelwelle und mittels durchzuführen. Dazu wurden in der Au- erzeugen kurzzeitige Drehmomentspitzen. Diese tomobilindustrie die Qualitätsfähigkeitskenngrösse führen in Getrieben zu Geräuschentwicklungen cg eingeführt. Nur Prüfmittel mit einem cg-Wert und Verschleiß. Die Schwingungen belasten aber von über 1.33 dürfen nach diesem Standard in der auch die Kurbelwelle mechanisch, wodurch es Qualitätssicherung eingesetzt werden. zu Torsionsbrüchen kommen kann. Die Aufga- Zur Prüfung von Schichtstärken von Haftvermitt- be eines Drehschwingungsdämpfers liegt in der lern wurden in der Vergangenheit Wirbelstrom- Dämpfung dieser Radialschwingungen. Der Dreh- oder magnet-induktive Messgeräte eingesetzt. schwingungsdämpfer besteht aus einer Sekundär- Diese weisen auf gestrahlten und beschichteten masse (Schwungring) und Primärmasse (Gehäu- Oberﬂächen eine Standardabweichung typischer- se). Der von Schwungring und Gehäuse einge- weise von mehreren µm auf. Daraus ergeben sich schlossene Raum wird von einem Gummi ausge- bei Toleranzfenstern von 10µm oder 20µm cg- füllt. Werte von deutlich unter 1.33. Diese Messgeräte sind also nicht für die Qualitätssicherung zugelas- sen. Seit 2015 setzen Hersteller von Drehschwingungs- dämpfern den CoatMaster zur Qualitätssicherung ein und setzen somit die hohen Vorgaben von der Automobilindustrie um. Der CoatMaster misst be- rührungslos die Schichtdicken von Haftvermittlern bei einem Messfehler von 70nm (= 0.07µm). Dies entspricht einem cg-Wert von 1.5 und erfüllt damit die modernen Anforderungen der Automobilindus- trie. Fig. 1: Schnitt durch einen Drehschwingungsdämpfer. Durch den Einsatz des CoatMasters zur Qua- Bei der Herstellung der Drehschwingungdämpfer litätssicherung in der Produktion von Dreh- werden die Innenseiten von Schwungring und Ge- schwingungsdämpfern erbringen Hersteller von häuse mit einem Haftvermittler beschichtet. Bei ei- Drehschwingungsdämpfern für ihre Kunden einen nem anschliessenden Vulkanisierungsprozess bei wichtigen verlässlichen Nachweis der hohen Qua- einer Temperatur von 120°C bis 160°C wird eine litätsstandards der Automobilindustrie. dauerhafte Verbindung von Schwungring, Gum- mierung und Gehäuse hergestellt.

www.zhaw.ch 34 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.31 Entwicklung eines Messgeräts für die praktische Anwen- dung der Thermischen Schichtprüfung an Kunst und Kul- turgut

Die Thermische Schichtprüfung ist ein bildgebendes, berührungsloses und zerstörungs- freies Untersuchungsverfahren, das in der Industrie zur Lokalisierung, Visualisierung und Quantiﬁzierung von verdeckten Schäden an beschichteten Oberﬂächen eingesetzt wird. In einer vorbereitenden KTI-Machbarkeitsstudie konnte nun aufgezeigt werden, dass das Ver- fahren auch in der Konservierung und Restaurierung ein grosses Potential hat. Es wurden zahlreiche Anwendungsmöglichkeiten nachgewiesen, wie z. B. das Aufspüren von Delami- nationen an einer Malschicht, Fassung oder Lackierung. Des Weiteren wurde bereits ein Prototyp eines Messgeräts zur praktischen Anwendung des Verfahrens an Kunst und Kul- turgut entwickelt. Im Rahmen des aktuellen KTI-Forschungsprojekts soll nun durch dessen gezielte Weiterentwicklung ein für KonservatorInnen geeignetes, einfach zu bedienendes Messinstrument geschaffen werden. Contributors: A. Bariska, S. Hauri, B. Rutz, M. Torroni, B. Schmid, T. Nguyen, U. Vögeli, N. Reinke Partners: Winterthur Instruments AG und andere Funding: KTI Duration: 2015–2016

In der Industrie wird das Verfahren der Ther- wie zur Dokumentation und Beurteilung des Erhal- mischen Schichtprüfung zur Qualitätskontrolle an tungszustands eines Kunstwerks. Beschichtungen oder Verbundwerkstoffen einge- Es wird ein Prototyp für die praktische Anwendung setzt. In der Konservierung und Restaurierung der Thermischen Schichtprüfung im aktuellen Pro- kommt es – abgesehen von einigen experimen- jekt weiterentwickelt, um einerseits die Zuverläs- tellen Anwendungen – noch nicht zum Einsatz. sigkeit der Messergebnisse zu optimieren, deren Hier gab es bisher keine messtechnische Möglich- Auswertung und Interpretation zu erleichtern und keit, Delaminationen aufzuspüren. Im Rahmen ei- andererseits weitere Anwendungsgebiete zu er- ner MA-Thesis und einer KTI-Machbarkeitsstudie schliessen. Dazu gilt es, den Einfluss der Ober- wurde nun die Eignung des Verfahrens für diesen flächenbeschaffenheit in den Messergebnissen zu Bereich nachgewiesen. So kann es z.B. zur Loka- reduzieren, u.a. durch die Evaluation alternati- lisierung von Lockerungen an der Malschicht ei- ver Anregungstechniken. Weiter soll erstmals eines Gemäldes, der Fassung einer Skulptur, der ne tomografische Untersuchungsmethode basie- Lackierung eines Oldtimers oder einem furnierten rend auf der Thermischen Schichtprüfung entwi- Möbelstück eingesetzt werden. Des Weiteren eig- ckelt werden, die Aussagen über die Tiefenlage net es sich zur Visualisierung von Unterzeichnun- eines Schadens ermöglicht. Die Messergebnisse gen, unter einer Malschicht verborgenen Insek- werden zudem durch die Überlagerung mit den Bil- tenfrassgängen oder hohlstehenden Putzen und dern einer zusätzlichen Kamera (VIS) leichter zu zur Überprüfung von Festigungsmassnahmen so- interpretieren sein.

Fig. 1: Nadelholzbrett mit künstlichen Insektenfrassgängen und darüber liegendem Furnier, Putzabhebungen (1) und Putz- ausbesserung (2) an historischem Mauerwerk, Ölgemälde (BHM) mit Blasenbildung in der Malschicht im Normallicht (oben) und als Phasenbild (unten).

Zürcher Fachhochschule 35 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.32 Blaues Licht aus neuen Materialien

Um kräftige Farben in einem OLED Fernseher zu erzeugen, werden Materialien benötigt, die tief-blaues Licht erzeugen können. An der Universität Zürich werden solche Materialien synthetisiert, und am ICP konnten erstmals OLEDs mit diesen neu entwickelten Materialien hergestellt werden.

Students: Quan Ky Ha, Naratip Sriutamayothin

Category: Bachelor of Science, Semesterprojekt Mentoring: K. Pernstich, M. Regnat, K. Venkatesan (Universität Zürich) Handed In: Dezember 2015

Vereinfacht gesprochen, entsteht das Licht in einen Materialien in der OLED. ner organischen Leuchtdiode (OLED) durch das Erfreulicherweise konnten funktionierende OLEDs Zusammentreffen der positiven und negativen La- hergestellt werden, und Abb. 1 zeigt das gemes- dungen aus der Spannungsquelle. Damit aus den sene Spektrum des emittierten Lichts. Der Haupt- Ladungen tatsächlich Licht (und nicht Wärme) er- anteil liegt bei 490 nm, das etwas langwelliger zeugt wird, sind spezielle Emitter-Moleküle not- (grünlicher) ist als erwartet. In einem nächsten wendig. Am Departement für Chemie der Univer- Schritt müsste man die Konzentration der Emitter- sität Zürich forscht die Gruppe von Dr. Venkatesan Moleküle variieren, und auch ein anderes Matrix- an neuartigen Molekülen, die in einer OLED blau- Material verwenden, um ein noch tieferes Blau zu es Licht erzeugen können. Die Besonderheit die- erhalten. Die Messungen helfen dabei die weite- ser Moleküle besteht darin, dass sie das Element re Entwicklung voranzutreiben, und die Resultate Gold verwenden, während vergleichbare Moleküle sollen auch in einer internationalen Zeitschrift ver- die noch teureren und selteneren Elemente Iridi- öffentlicht werden. um oder Platin verwenden. Stabile blaue Emitter- Moleküle sind im Markt sehr gefragt, und derzeit gibt es noch grossen Bedarf nach besseren Mate- rialien. In dieser Zusammenarbeit wurden die weltweit erstmals synthetisierten Moleküle der Universität Zürich verwendet, um im hauseigenen Labor des Institute of Computational Physics OLEDs her- zustellen. Die einzelnen Schichten wurden dazu aus Lösung abgeschieden oder durch thermisches Verdampfen aufgebracht. Eine grosse Schwie- rigkeit bestand darin, die richtige Material- und Schichtkombination zu ﬁnden, denn blaues Licht ist energiereicher als rotes oder grünes Licht, und dies stellt besondere Anforderungen an die einzel- Abb. 1: Gemessenes Lichtspektrum der blauen OLED.

www.zhaw.ch 36 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

1.33 Herstellung von Perowskit-Solarzellen

Perowskit-Solarzellen sind eine vielversprechende Entwicklung, welcher in Zukunft ein ho- hes Potential an der Energiewende beizumessen ist. Ziel dieses Projektes war die Herstel- lung solcher Solarzellen auch an der ZHAW zu ermöglichen. Hiermit sollte der Grundstein für weitere Projekte auf diesem Gebiet gelegt werden.

Students: Jonas Dunst

Category: MSE Vertiefungsarbeit Mentoring: K. Pernstich Handed In: Februar 2016

Eine bemerkenswerte Errungenschaft der definieren, welcher homogene und feinkristalline Perowskit-Solarzellen liegt darin, dass mit ihnen Perowskit-Schichten liefert welche in Abb. 1 unten in verhältnismässig kurzer Forschungszeit be- rechts dargestellt ist. Hiermit wurden im Anschluss reits Effizienzen von über 20% erzielt wurden. Solarzellen produziert, welche mit dem Messge- Zudem ist der Energieaufwand für deren Herstel- rät Paios der Firma Fluxim charakterisiert werden lung weitaus geringer als jener für konventionel- konnten. Dies ergab u.a. die in Abb. 2 dargestell- le Silizium-Zellen. Allerdings besitzen Perowskit- te Strom-Spannungs-Kennlinie. Sie ist charakteris- Solarzellen auch noch einiges an Verbesserungs- tisch für eine Solarzelle, kommt aber noch nicht an und Forschungspotential. So sind die Zellen meist die erzielten Rekordeffizienzen heran. nicht langzeitstabil und weisen eine Hysterese auf. Weiter stellt die Reproduzierbarkeit bereits im La- bormassstab eine Herausforderung dar. Das langfristige Ziel wäre es, durch simulations- basierte Charakterisierung dieses Solarzellentyps ein tieferes Verständnis für dessen Funktionswei- se zu bekommen und dadurch zur Verbesse- rung beizutragen. Als ersten Schritt in diese Rich- tung sollte in diesem Projekt ein Herstellverfah- ren für Perowskit-Solarzellen gemäss aktuellem Stand der Forschung etabliert werden. Dies ist von Bedeutung, da zur Modellierung zuverlässige Messwerte von definierten Solarzellen notwendig Abb. 1: Mikroskop Aufnahmen verschiedener Perowskite sind. Bei messtechnischer Charakterisierung di- Kristallstrukturen. rekt nach der Herstellung in der Inertgas-Glovebox unseres Labors erübrigt sich eine Verkapselung und ein Transport der Zelle. Für dieses Vorhaben musste erst einmal grundle- gendes Basiswissen auf diesem neuen Fachge- biet erarbeitet werden. Schliesslich konnten Her- stellungsverfahren aus verschiedenen Publikatio- nen auf ihre Eignung geprüft werden. Dabei stellte sich heraus, dass die Kontrolle des Kristallisations- prozesses der Perowskitschicht die grösste Her- ausforderung darstellt. In Abb. 1 sind Mikroskop- aufnahmen einiger dieser Schichtstrukturen dargestellt.

Schliesslich ist es gelungen einen Prozess zu Abb. 2: JV-Kennlinie der hergestellten Solarzellen.

Zürcher Fachhochschule 37 www.zhaw.ch Institute of Computational Physics Research Report 2015

1.34 Modellbasierter Reglerentwurf für die Temperaturregel- ung eines Kryostaten

Für die Untersuchung von grundlegenden Mechanismen in organischen Leuchtdioden und Solarzellen müssen Bauteile oft auf -150◦C oder tiefer gekühlt werden. Aus solchen Tief- temperaturmessungen lassen sich genaue Modelle der physikalischen Vorgänge ableiten. In dieser Arbeit wurde ein modellbasierter Regler für ein selbst gebautes Kühlgerät - einem so genannten Kryostaten - entwickelt, der sowohl die Kühlleistung also auch die Tempera- tur des Kryostaten exakt regelt, und somit das zu untersuchende Bauteil kühlt.

Students: Oliver Keller, Reto Meier

Category: Bachelor of Science, Semesterprojekt Mentoring: K. Pernstich, O. Fluder (IMS) Handed In: Dezember 2015

Ein erster Prototyp des Kryostaten wurde über- arbeitet bis er die gewünschten Anforderungen erfüllte. Dieser wurde dann in einem komplexen Simulink-Modell abgebildet (siehe Abb. 1). Es wurden etliche Messungen durchgeführt um das Mo- dell zu validieren. Das sehr genaue Modell erlaubt die Auslegung des Reglers am Modell durchzufüh- ren, was sich als sehr ressourcensparend erwies. Abb. 1: Simulink Modell des Kryostaten.

Der verbesserte Kryostat konnte dank des opti- mierten Reglers den Temperatursollwert sehr ge- Die Regelstrecke ist ein gekoppeltes System mit nau erreichen: die Ist-Temperatur überschwingt den beiden Stellwerteingängen „heating power for um weniger als 0.4°C, und die statische Ab- pressure“ um den ﬂüssigen Stickstoff im Dewer weichung beträgt maximal 0.05°C. Es ist nicht zu erwärmen, um so einen Druck im Dewer zu nur möglich einzelne Temperaturwerte vorzuge- erzeugen, der den Stickstoff in den Probenträger ben, sondern ebenfalls Temperaturrampen mit ei- drückt, und „heating power“ der die Heizung des ner Steigung von bis zu 0.2°C/s zu fahren. Probenträgers ansteuert. Als Messgrössen stehen Das Entwicklungsstadium des Kryostaten beﬁn- der Druck im Dewer „actual pressure“ und die Tem- det sich zurzeit zwischen dem Prototypen und der peratur des Probenträgers „actual temp“ zur Ver- Markteinführung. Bei der Entwicklung wurde auf fügung. Der Regler besteht somit aus zwei Pfa- niedrige Herstellkosten des Kryostaten und kos- den für dieses gekoppelte System: eine Kaskade tengünstige Elektronik-Ansteuerung geachtet. Ei- für die Druck- und Temperaturregelung im Dewer ne Weiterentwicklung und Kommerzialisierung die- und ein Temperaturregler für den Probenträger mit ses Kryostaten ist in KTI Projekt-Zusammenarbeit Koppelung auf den ersten Regler. mit Fluxim AG geplant.

Abb. 2: Gemessene Temperatur des Kryostaten. Die statische Regelgenauigkeit beträgt 0.05◦C.

www.zhaw.ch 38 Zürcher Fachhochschule Appendix

A.1 Student Projects

L.ANGST,M.MONEGO, Detection and characterisation of gold nanorods in biological tissue, Be- treuer: M. Bonmarin, Firmenpartner: Dermolockin GmbH, Winterthur, Projektarbeit Systemtech- nik.

A.ARRIBAS, Simulation elektro-statischer Beschichtungsverfahren, Betreuer: G. Boiger, Firmen- partner: J. Wagner AG, Altstätten, Projektarbeit Energie und Umwelt.

P. BÖSCH,M.ZEHNDER, Hyperthermia therapy with nanorods - Designing an Infrared-LED excitation system, Betreuer: M. Bonmarin, Firmenpartner: Dermolockin GmbH, Winterthur, Bachelo- rarbeit Systemtechnik.

D. BALTA,M.SCHMID, Optimierung der Sekundärlufteindüsung in Verbrennungsöfen mittels thermisch-ﬂuidischer CFD-Modellierung in openFOAM, Betreuer: T. Hocker, Firmenpartner: Umweltin- genieurbüro I.C.E. AG, Wil, Bachelorarbeit Maschinentechnik.

A.BLEULER,N.SALIHI,J.STORSKOGEN, Handgerät für die Messung von Schichtdicken im Baubereich, Betreuer: N. Reinke, Projektarbeit Systemtechnik.

M.BOLDRINI, Simulation von hochfrequenten Dosiervorgängen mittels OpenFoam, Betreuer: G. Boiger, Firmenpartner: Novartis Pharma AG, Basel, Vertiefungsarbeit Master of Science.

M.BRUMM, Development of a Sound Coding Algorithm for Optical Cochlear Implants, Coach: B. Ruhstaller, Master thesis for Master of Science in Engineering.

S.DICHT,I.MEULI, Weiterentwicklung eines Holzvergasungsreaktors, Betreuer: G. Boiger, Fir- menpartner: Berchtold Apparatebau AG, Thalwil, Bachelorarbeit Maschinentechnik.

J.DUNST, Fabrication and Characterization of Perovskite Solar Cells, Betreuer: K. Pernstich, B. Ruhstaller, Vertiefungsarbeit Master of Science in Engineering.

C.EDELMANN,K.SIGNER, Efﬁzienzsteigerung elektro-statischer Beschichtungsverfahren - Arbeit 2, Betreuer: G. Boiger, N.Reinke, Firmenpartner: J.Wagner AG, Altstätten, Bachelorarbeit Energie und Umwelt.

S.EHRAT,C.WERDENBERG, Aufbau eines Prüfstands für Druckverlustmessungen, Betreuer: T. Hocker, D. Meier, Firmenpartner: Hexis AG, Winterthur, Projektarbeit Energie und Umwelt.

F. FRIES, Entwicklung eines mikroskopischen 3D-Kraftsensors, Betreuer: N. Reinke, Projektarbeit Systemtechnik.

F. FRIES, Entwicklung einer hochauﬂösenden Mikrobolometer-Kamera, Betreuer: N. Reinke, Bach- elorarbeit Systemtechnik.

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CH.HABLÜTZEL,M.SCHWEIZER, Efﬁzienzsteigerung elektro-statischer Beschichtungsverfahren - Arbeit 1-2, Betreuer: G. Boiger, N. Reinke, Firmenpartner: J.Wagner AG, Altstätten, Bachelorar- beit Energie und Umwelt/Maschinentechnik.

QUAN KY HA,NARATIP SRIUTAMAYOTHIN, OLEDs aus neuen Materialien, Betreuer: K. Pernstich, M. Regnat, K. Venkatesan (Universität Zürich), Semesterprojekt.

OLIVER KELLER,RETO MEIER, Modellbasierter Reglerentwurf für die Temperaturregelung eines Kryostaten, Betreuer: K. Pernstich, O. Fluder (IMS), Semesterprojekt.

K.LAPAGNA, Calculation of Light Scattering Distribution Functions based on Fourier and Micro- facets Methods for 3D Textures, Coach: B. Ruhstaller, Master thesis for Master of Science in Engineering.

J.MARON, Entwicklung eines neuartigen Kupferelektrolyse Verfahrens mittels Simulation, Model- lierung & experimenteller Validierung, Betreuer: G. Boiger, Firmenpartner: ICP intern, Projektar- beit Energie und Umwelttechnik.

D. MEIER, Thermisch-ﬂuidische Optimierung von Interkonnektoren von Brennstoffzellen vom Typ SOFC, Betreuer: T. Hocker, C. Meier, Firmenpartner: Hexis AG, Winterthur, Vertiefungsarbeit Master of Science.

T. MESAREC, Thermische Optimierung eines Lasttrennschalters, Betreuer: T. Hocker, Firmenpart- ner: Woehner AG, Rödental (D), Vertiefungsarbeit Master of Science.

S.MEUNIER, Time resolved, wavelength selective electroluminescence measurement setup, Su- pervisor: P. Losio, Internship.

E.MEYER, Entwicklung eines neuartigen Kupferelektrolyse Verfahrens - Rahmenbedingungen und Konstruktion, Betreuer: G. Boiger, Firmenpartner: ICP intern, Bachelorarbeit Maschinentechnik.

F. MÜLLER, Application Software for Large-Area Modeling of Photovoltaics and OLEDs, Coach: B. Ruhstaller, Master thesis for Master of Science in Engineering.

T. OTT, Modellierung von Mikrostrukturparametern eines Diaphragmas zu PH Messung, mittels OpenFoam, Betreuer: G. Boiger, Firmenpartner: Mettler Toledo AG, Urdorf, Vertiefungsarbeit Master of Science.

M.RUTZER,S.SIGG, Entwicklung einer neuen, thermischen Methode zur Hautkrebsbekämpfung, Betreuer: G. Boiger, M. Bonmarin, Firmenpartner: Dermolockin GmbH, Winterthur, Bachelorarbeit Energie und Umwelttechnik.

J. F. SCHREYER,C.GRIESSER, Multispektrales Lebensmittel-Erkennungssystem, Betreuer: N. Re- inke, Projektarbeit Systemtechnik.

L.STEPANOVA, 3D ray tracing algorithm for light outcoupling from microstructured OLEDs, Advi- sors: C. Kirsch, R. Knaack, B. Ruhstaller, Master thesis EPFL.

S.WEILENMANN, Entwicklung eines neuartigen Kupferelektrolyse Verfahrens - Simulation und Modellierung, Betreuer: G. Boiger, Firmenpartner: ICP intern, Bachelorarbeit Maschinentechnik.

S.ZANGERL, Entwicklung eines mehrschichtigen, thermischen Hautmodells mittels OpenFoam, Betreuer: G. Boiger, Firmenpartner: Dermolockin GmbH, Winterthur, Vertiefungsarbeit Master of Science. www.zhaw.ch 40 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

A.2 Scientiﬁc Publications

S.ALTAZIN,C.REYNAUD,U.M.MAYER, T. LANZ,K.LAPAGNA,R.KNAACK,L.PENNINCK, C.KIRSCH, K. P. PERNSTICH,S.HARKEMA, D. HERMES,B.RUHSTALLER, Simulations, Mea- surements, and Optimization of OLEDs with Scattering Layer, SID Symposium Digest of Technical Papers, 46 (1), 564–567, 2015.

S.ALTAZIN,C.REYNAUD,U.M.MAYER, T. LANZ,K.LAPAGNA,R.KNAACK,L.PENNINCK, C.KIRSCH, K.P. PERNSTICH,S.HARKEMA, D. HERMES,B.RUHSTALLER, Simulations, Mea- surements, and Optimization of OLEDs with Scattering Layer, SID Symposium Digest of Technical Papers, 46 (1), 564-567, 2015.

S.ALTAZIN,S.ZÜFLE,L.PENNINCK,B.RUHSTALLER, Combining Simulations and Experiments to Study the Impact of Polar OLED Materials, IMID Digest, 2015.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Moderne Qualitätssicherung bei Haftvermittlerschichten, Journal für Oberﬂächentechnik.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Schichtdickenmessung direkt nach dem Auftragen, Journal für Oberﬂächentechnik.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Closed-Loop-Regelung der Schichtstärke in Pulverbeschichtungsanlagen, Journal für Oberﬂächen- technik.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Viel Pulver sparen, mo Oberﬂäche.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Pulver mikrometergenau applizieren, besser lackieren.

G.BOIGER, System Dynamic Modelling Approach for resolving the Thermo Chemistry of Wood Gasiﬁcation, Int. J. of Multiphysics, 9 (2), 137–155, 2015.

M.BONMARIN, FA. LE GAL, A lock-in thermal imaging setup for dermatological applications, Skin Research and Technology, 21, 284–290, 2015.

H.CHEN,O.MA, Y. ZHOU,Z.YANG,M.JAZBINSEK, Y. BIAN,N.YE, D. WANG,H.CAO, W. HE, Engineering of Organic Chromophores with Large Second-Order Optical Nonlinearity and Supe- rior Crystal Growth Ability, Crystal Growth and Design, 15, 5560–5567, 2015.

O.DÜRR, Y. PAUCHARD, D. BROWARNIK,R.AXTHELM,M.LOESER, Deep Learning on a Rasp- berry Pi for Real Time Face Recognition, EG 2015 - Posters 11-12, 2015.

S.JENATSCH, T. GEIGER,J.HEIER,C.KIRSCH, F. NÜESCH,A.PARACCHINO, D. RENTSCH, B.RUHSTALLER,A.C.VÉRON,R.HANY, Inﬂuence of chemically p-type doped active organic semiconductor on the ﬁlm thickness versus performance trend in cyanine/C60 bilayer solar cells, Science and Technology of Advanced Materials, 16 (3), 035003, 2015.

L.KELLER,A.HOLGER,I.MANKE, Impact of sand content on solute diffusion in Opalinus Clay, Applied Clay Sciences, 134, 134–142, 2015.

Zürcher Fachhochschule 41 www.zhaw.ch Institute of Computational Physics Research Report 2015

L.KELLER, On the representative elementary volumes of clay rocks at the mesoscale, Journal of Geology and Mining Research, 7, 58–64, 2015.

L.KELLER,L.HOLZER, P. GASSER,R.ERNI,M.ROSSELL, Intergranular pore space evolution in MX80 bentonite during a long-term experiment, Applied Clay Sciences, 104, 150–159, 2015.

J. T. KIM, O. P. KWON, F. D. J. BRUNNER,M.JAZBINSEK,S.H.LEE, P. GUNTER, Phonon Modes of Organic Electro-Optic Molecular Crystals for Terahertz Photonics, Journal of Physical Chemi- stry C, 119, 10031–10039, 2015).

J. T. KIM, O. P. KWON,M.JAZBINSEK, Y. C. PARK, Y. S. LEE, First-Principles Calculation of Tera- hertz Absorption with Dispersion Correction of 2,2 ‘-Bithiophene as Model Compound, Journal of Physical Chemistry C, 12598–12607, 2015.

E.KNAPP,B.RUHSTALLER, Analysis of negative capacitance and self-heating in organic semiconductor devices, J. Appl. Phys., 117, 135501, 2015.

T. LANZ,K.LAPAGNA,S.ALTAZIN,M.BOCCARD, F.J. HAUG,C.BALLIF,B.RUHSTALLER, Light trapping in solar cells: numerical modeling with measured surface textures, Optics express, 23 (11), A539-A546, 2015.

S.H.LEE,B.J.KANG,J.S.KIM, B. W. YOO,J.H.JEONG,K.H.LEE,M.JAZBINSEK, J. W. KIM, H.YUN, J. T. KIM, Y. S. LEE, F. ROTERMUND, O. P. KWON, New Acentric Core Structure for Or- ganic Electrooptic Crystals Optimal for Efﬁcient Optical-to-THz Conversion, Advanced Optical Materials, 3, 756–762, 2015.

S.H.LEE, B. W. YOO,M.JAZBINSEK,B.J.KANG, F. ROTERMUND, O. P. KWON, Organic ionic electro-optic crystals grown by speciﬁc interactions on templates for THz wave photonics, Cryst- EngComm 17, 4781–4786, 2015.

S.H.LEE, B. W. YOO,H.YUN,M.JAZBINSEK, O. P. KWON, Organic styryl quinolinium crystal with aromatic anion bearing electron-rich vinyl group, Journal of Molecular Structure, 1100, 359– 365, 2015.

M.LINDER, T. HOCKER,C.MEIER,L.HOLZER,K.A.FRIEDRICH,B.IWANSCHITZ,A.MAI, J.A.SCHULER, A model-based approach for current voltage analyses to quantify degradation and fuel distribution in solid oxide fuel cell stacks, Journal of Power Sources, 288, 409–418, 2015.

M.LINDER, T. HOCKER,L.HOLZER,O.PECHO,K.A.FRIEDRICH, T. MORAWIETZ,R.HIES- GEN,R.KONTIC,B.IWANSCHITZ,A.MAI,J.A.SCHULER, Ohmic resistance of nickel inﬁltrated chromium oxide scales in solid oxide fuel cell metallic interconnects, Solid State Ionics, 283, 38– 51, 2015.

P. LOSIO,O.CAGLAR,J.CASHMORE,J.HÖTZEL,S.RISTAU,J.HOLOVSKY,Z.REMES,I.SINICCO, Light management in large area thin-ﬁlm silicon solar modules, Solar Energy Materials and Solar Cells, 143, 375–385, 2015.

J.LUO,Z.LI,S.NISHIWAKI,M.SCHREIER,M.MAYER, P. CENDULA, Y. H. LEE,K.FU,A.CAO, M.K.NAZEERUDDIN, Y. E. ROMANYUK,S.BUECHELER,S.TILLEY,L..H.WONG,M.GRÄTZEL, Targeting Ideal Dual-Absorber Tandem Water Splitting Using Perovskite Photovoltaics and CuInx Ga1-xSe2 Photocathodes, Advanced Energy Materials, 5, 2015.

O.PECHO,A.MAI,B.MÜNCH, T. HOCKER,R.FLATT,L.HOLZER, 3D Microstructure Effects in Ni-YSZ Anodes: Inﬂuence of TPB Lengths on the Electrochemical Performance, Materials, 8, 7129–7144, 2015. www.zhaw.ch 42 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

O.PECHO,L.HOLZER,Z.YANG,J.MARTYNCZUK, T. HOCKER,R.FLATT,M.PRESTAT, Influence of strontium-rich pore-filling phase on the performance of La0.6Sr0.4CoO3−δ thin-film cathodes, Journal of Power Sources, 274, 295–303, 2015.

O.PECHO,O.STENZEL,B.IWANSCHITZ, P. GASSER,M.NEUMANN, V. SCHMIDT,M.PRESTAT, T. HOCKER,R.FLATT,L.HOLZER, 3D Microstructure Effects in Ni-YSZ Anodes: Prediction of Effective Transport Properties and Optimization of Redox Stability, Materials, 8, 5554–5585, 2015.

N.REINKE, Was ist Licht?, Aktuelle Technik, 2015.

Y. SAFA, T. HOCKER, A validated energy approach for the post-buckling design of micro-fabricated thin ﬁlm devices, Applied Mathematical Modelling, 39, 483–499, 2015.

S.ZÜFLE,M.NEUKOM,S.ALTAZIN,M.ZINGGELER,M.CHRAPA, T. OFFERMANS,B.RUH- STALLER, An Effective Area Approach to Model Lateral Degradation in Organic Solar Cells, Adv. Energy Mater. 5, 1500835, 2015.

A.3 Book Chapters

A.KHARAGHANI,C.KIRSCH, T. METZGER,E.TSOTSAS, Liquid Distribution and Structural Changes During Convective Drying of Gels, In Colloid Process Engineering, Editors M. Kind, W. Peukert, H. Rehage, H. P. Schuchmann; Springer, 93–112, 2015.

A.4 News Articles

M. Bonmarin, Hautkrankheiten mit Hightech-Verfahren aufspüren, Impact Magazine, Dezember, 2015.

T. Hocker, Perfecting the chocolate making process, International Innovation, December, 2015.

A. Bariska, S. Hauri, B. Rutz, M. Torroni, B. Schmid, T. Nguyen, U. Vögeli, N. Reinke, Elektrostatis- che Pulverbeschichtung mit Closed-Loop Regelkreis, mo Oberﬂäche, 2015.

A.5 Conferences and Workshops

S.ALTAZIN,C.REYNAUD,U.MAYER,L.PENNINCK,K.LAPAGNA, T. LANZ,C.KIRSCH,R.KNAACK, K.PERNSTICH,S.HARKEMA, D. HERMES,B.RUHSTALLER, Scattering particle layers for light extraction in OLEDs: numerical design and experiment, International Meeting on Information Display IMID, Daegu, 2015.

S.ALTAZIN,L.PENNINCK,C.REYNAUD,U.M.MAYER,K.LAPAGNA, T. LANZ,C.KIRSCH, R.KNAACK,K.PERNSTICH,B.RUHSTALLER,S.HARKEMA, D. HERMES, Simulations, measurements and optimization of OLEDs with scatter layer, SID International Symposium, San Jose, 2015.

R.AXTHELM, A finite element simulation of high density pedestrian flow, TGF15 Traffic and Gran- ular Flow, Delft, 2015.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Zerstörungsfreie Prüfung von Faserverbundbauteilen, Stuttgarter Produktionsakademie Fraunhofer

Zürcher Fachhochschule 43 www.zhaw.ch Institute of Computational Physics Research Report 2015

IPA, Stuttgart, 2015.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Berührungslose Schichtdickenmessung von Nass- und Pulverlacken, Winterthurer Lack und Far- ben Symposium, Winterthur, 2015.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Industrie 4.0 in der Oberﬂächentechnik - Fallstudien, Winterthurer Oberﬂächentag, Winterthur, 2015.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Berührungslose Schichtdickenmessung in der Lackentwicklung, European Coatings Show, Nürn- berg, 2015.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Zerstörungsfreie Schicht- und Werkstoffprüfung, Control, Stuttgart, 2015.

A.BARISKA,S.HAURI,B.RUTZ,M.TORRONI,B.SCHMID, T. NGUYEN,U.VÖGELI,N.REINKE, Closed-Loop Beschichtung durch kontinuierliche Schichtdickenmessung, EPS Pulvertreff, Mün- chen, 2015.

G.BOIGER, OpenFoam based Modeling of Particle Motion and Deposition Processes in Electro Static Fields, 10th Int. Conference of Multiphysics, London, 2015.

M.BONMARIN,L.HOLZER, On the potential of active thermal imaging for skin cancer diagnostic, 25. Deutscher Hautkrebskongress, München, 2015.

M.BONMARIN,L.HOLZER,B.MUENCH,B.SCHMID, Aktive Thermographie für Hautkrebs Diag- nose, 25th Deutscher Hautkrebskongress der Arbeitsgemeinnschaft Dermatologische Onkologie - ADO, München, 2015.

L.CAPONE,L.HOLZER,A.LAMIBRAC,J.DUJC,O.STENZEL, F. N. BÜCHI,J.SCHUMACHER, Voxel-based modelling of water distribution in PEM porous media, 12th Symposium on Fuel Cell and Battery Modelling and Experimental Validation – ModVal 12, Freiburg, 2015.

L.CAPONE,A.LAMIBRAC,J.SCHUMACHER, A novel Monte Carlo technique for simulating liquid water distribution in gas diffusion layers of PEFCs, 2nd SCCER-Mobility Annual Conference, Zürich, 2015.

L.CAPONE,L.HOLZER,A.LAMIBRAC, F. BUCHI¨ ,J.SCHUMACHER, Voxel-based modeling of water distribution in PEM porous media, 12th Symposium on Fuel Cell and Battery Modelling and Experimental Validation – ModVal 12, Freiburg am Brisgau, 2015.

L.CAPONE,A.LAMIBRAC,J.DUJC,J.SCHUMACHER, F. BUCHI¨ , A novel Monte Carlo scheme for liquid water distribution in gas diffusion layers of PEFCs, Annual Conference SCCER Mobility, Zürich, 2015.

P. CENDULA,L.STEIER,S.TILLEY,M.MAYER,M.GRÄTZEL,J.SCHUMACHER, Optoelectronic Modeling of Hematite Photoelectrodes, 12th Symposium on Modeling and Experimental Validation of Fuel Cells and Batteries, Freiburg am Breisgau, 2015.

P. CENDULA,L.STEIER,S.TILLEY,M.MAYER,M.GRÄTZEL,J.SCHUMACHER, Optoelectronic Modeling of Hematite Photoelectrodes, Solar Fuel Conference : Light Driven Water Splitting Using Semiconductor Based Devices, Mallorca, 2015.

P. CENDULA,L.STEIER,S.TILLEY,M.MAYER,M.GRÄTZEL,J.SCHUMACHER, Optoelectronic Modeling of Hematite Photoelectrodes, 1st International Solar Fuel Conference, Uppsala, 2015. www.zhaw.ch 44 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

M.DOLD, T. HOCKER,M.LINDER,L.HOLZER,A.MAI,J.A.SCHULER, Model-based analysis of electrochemical impedance spectra of solid oxide fuel cells, 12th Symposium for Fuel Cell and Battery Modeling and Experimental Validation ModVal 12, Freiburg, 2015.

J.DUJC,M.COCHET,A.FORNER CUENCA,L.CAPONE,J.SCHUMACHER, P. BOILLAT, 3D simulation of membrane electrode assembly with hydrophilic treated GDL, 2nd SCCER-Mobility Annual Conference, Zürich, 2015.

J.DUJC,L.CAPONE,J.SCHUMACHER,J.BIESDORF, P. BOILLAT, Numerical simulation of liquid water saturation in cathode side gas diffusion layers of PEFCs, 12th Symposium on Fuel Cell and Battery Modelling and Experimental Validation – ModVal 12, Freiburg am Brisgau, 2015.

G.FRITSCHER,S.KOGLER T. HUBER,A.OPITZ,J.FLEIG,A.HEEL, D. BURNAT,L.HOLZER, Electrochemical properties of La0.2Sr0.7TiO3 thin ﬁlm electrodes under reducing conditions, EMRS – European Materials Research Society Spring Meeting, Lille, 2015.

J.FUCHS,G.BOIGER,C.MEIER,R.DENZLER, Simulation of heat transfer processes within a fuel cell system based on OpenFoam, 12th Symposium for Fuel Cell and Battery Modeling and Experimental Validation - ModVal 12, Freiburg, 2015.

M.GORBAR, Y. DE HAZAN, D. PENNER,L.HOLZER,G.BOIGER,R.J.CERVERA,I.A.SCHNEI- DER, Extrusion of YSZ diaphragms with controlled porosity used as liquid junction in pH electrodes, 14th Int. Conf of Europ. Ceram. Soc. ECERS, Toledo, 2015.

A.HEEL,L.HOLZERETAL., CO2 Reduction & Reuse – Renewable Fuels for Efﬁcient Electricity Production, NRP70 Kick-off Meeting, Lucerne, 2015.

A.HEEL,R.KONTIC,L.HOLZER, P. STEIGER, D. FERRI,M.NACHTEGAAL,O.KRÖCHER,H.MA- DI,J. VAN HERLE,J.A.SCHULER,A.MAI, SERAN – Self-Regenerating Smart Materials for Solid Oxide Fuel Cells, 1st Biomass for Swiss Energy Future Conference, Villigen, 2015.

T. HOCKER, Teilnehmer an Podiumsdiskussion, Tagung über den Energiediskurs in der Schweiz, ZHAW, Departement für Angewandte Linguistik, Winterthur, 2015.

L.HOLZERAND T. HOCKER, Inﬂuence of Coffee-Bed Microstructure on Extraction and Quality, Swiss Food Research Meeting, Wädenswil, 2015.

L.HOLZER, Understanding the inﬂuence of electrode microstructure: methods and applications, 3rd Int. Workshop on degradation issues of Fuel Cells and Electrolysers (3rd DegIs), Santorini, 2015.

E.KNAPP,B.RUHSTALLER, Analysis of Self-Heating and Negative Capacitance in Organic Semi- conductors Devices, SID Display Week Technical Symposium, San Jose, 2015.

E.KNAPP,B.RUHSTALLER, Analysis of self-heating and trapping in organic semiconductor devices, SPIE Optics + Photonics, San Diego, 2015.

E.KNAPP, The Role of Self-Heating in the Electrical Characterization of Organic Semiconductors Devices, Theoretical Challenges in Organic Electronics, Heidelberg, 2015.

M.LINDER, T. HOCKER,C.MEIER,L.HOLZER,A.K.FRIEDRICH,B.IWANSCHITZ,A.MAI, J.A.SCHULER, Quantiﬁcation of SOFC stack degradation and fuel distribution based on current voltage data, 12th Symposium for Fuel Cell and Battery Modeling and Experimental Validation ModVal 12, Freiburg, 2015.

Zürcher Fachhochschule 45 www.zhaw.ch Institute of Computational Physics Research Report 2015

P. LOSIO, Simulation of Thin Film Silicon Solar Cells in industry, 8th Annual Meeting on Photonic Devices, Berlin, 2015.

V. ORAVA,O.SOUCEKˇ , P. CENDULA, Modeling of Non-isothermal Reacting Flow in Fluidized Bed Reactors, Comsol Conference, Grenoble, 2015.

V. ORAVA,O.SOUCEKˇ , P. CENDULA,J..O.SCHUMACHER,L.GUBLER, Multi-phase modeling of a hydrogen generator coupled to a PEM fuel cell, 12th Symposium on Modeling and Experimental Validation of Fuel Cells and Batteries, Freiburg am Breisgau, 2015.

V. ORAVA,O.SOUCEKˇ , P. CENDULA, Generalization of a multi-phase modeling of ﬂuidized bed reactors, Multiphase Flow 2015, Valencia, 2015.

O.PECHO,O.STENZEL,B.IWANSCHITZ,R.J.FLATT, T. HOCKER,L.HOLZER, Improved redox- stability of Ni-YSZ anodes based on 3D microstructure and experimental analyses, 12th Interna- tional Conference on Materials Chemistry (MC12), University of York, 2015.

O.PECHO,O.STENZEL,M.NEUMANN,B.IWANSCHITZ, V. SCHMIDT, T. HOCKER,R.J.FLATT, L.HOLZER, Optimization of redox stability and electrochemical performance of Ni-YSZ anodes based on detailed 3D microstructure analyses, Materials and Processes Graduate Symposium, ETH Zürich, 2015.

K.PERNSTICH, Organische Halbleiter für grossﬂächige Elektronik Anwendungen, Winterthurer Lack- und Farbensymposium 2015, Winterthur, 2015.

B.RUHSTALLER, Insights from Advanced Characterization and Modeling of Organic and Perovskite Solar Cells, Intl. Symposium on Organic Solar Cell Stability (ISOS-8), Rio de Janeiro, 2015.

B.RUHSTALLER, Combining Simulations and Experiments to Study the Impact of Polar OLED Ma- terials, Japan OLED Forum, Chiba University, 2015.

Y. SAFA, Developed model of the phase change kinetics in cocoa butter, simulation of cooling and solidiﬁcation processes. , "AK-Schoko Treffen" Meeting Day of Swiss Chocolate Industry, ETH- Zürich, 2015.

J.SCHUMACHER,J.DUJC,L.CAPONE,O.STENZEL,L.HOLZER,A.LAMIBRAC, F. N. BÜCHI, Parameterisation of macrohomogeneous models of proton exchange membrane fuel cells, 12th Symposium on Fuel Cell and Battery Modelling and Experimental Validation – ModVal 12, Freiburg, 2015.

S.ZÜFLE,M.NEUKOM,S.ALTAZIN, T. OFFERMANS,M.CHRAPA,B.RUHSTALLER, Humidity in- duced lateral degradation in Organic Solar Cells investigated by measurements and simulation, HOPV Conference, Rome, 2015.

S.ZÜFLE,M.NEUKOM, T. LANZ,M.ZINGGELER,M.CHRAPA, T. OFFERMANS,J.REINHARDT, U.WÜRFEL,B.RUHSTALLER, A 2D model for water diffusion in organic solar cells leading to lateral degradation, EMRS, Lille, 2015.

S.ZÜFLE,M.NEUKOM,S.ALTAZIN, T. OFFERMANS,M. HRAPA,B.RUHSTALLER, Humidity in- duced lateral degradation in Organic Solar Cells investigated by measurements and simulation, EMRS, Lille, 2015.

S.ZÜFLE,M.NEUKOM,S.ALTAZIN,B.RUHSTALLER, Combined Simulation and Electrical Char- acterization for OPV Stability Analysis, COST StableNextSol Meeting, Lille, 2015.

S.ZÜFLE,M.NEUKOM,B.RUHSTALLER, Complementary techniques to investigate degradation mechanisms in solar cells, PV Reliability Conference of the SwissPhotonics Network, Lugano, www.zhaw.ch 46 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

2015.

A.6 Public Events

B.FURRER, T. HOCKER,J.MUSIOLIK,N.ROSENBERGER, 2. Brennstoffzellenforum, Winterthur, Juni 2015.

N.REINKE,A.BARISKA, Winterthurer Oberﬂächentag 2014, Winterthur, Juni 2015.

J.SCHUMACHER, F. BUCHI¨ ,L.HOLZER,L.CAPONE,A.LAMIBRAC,J.DUJC, NFP70 Site Visit, Winterthur, November 2015.

A.7 Patents

R.DENZLER,A.MAI (HEXIS AG),C.MEIER (ICP), Brennstoffzellenmodul und Verfahren zum Betrieb eines Brennstoffzellenmoduls, Patent pending, Munich, 2015.

A.8 Prizes and Awards

The ICP spin-off Dermolockin GmbH was ﬁnalist of the Heuberger Jungunternehmer-Preis and received a cash prize of 50’000 CHF.

The Swiss Federal Foundation for Promotion of the National Economy through Scientiﬁc Research supported the ICP spin-off Dermolockin GmbH with an interest-free loan of 100’000 CHF.

Winterthur Instruments ist Finalist im Export Award des Switzerland Global Enterprise.

A.9 Teaching

R.AXTHELM, Analysis 1, HS15, Bachelor of Science.

R.AXTHELM, Lineare Algebra 2, FS15, Bachelor of Science.

R.AXTHELM, Numerik, HS15, Bachelor of Science.

G.BOIGER, Numerik 1 für IT, HS15, Bachelor of Science.

G.BOIGER, Systemphysik für Aviatik 1 – Praktikum, HS15, Bachelor of Science.

G.BOIGER, Systemphysik für Aviatik 2 – Praktikum, FS15, Bachelor of Science.

G.BOIGER, Advanced Thermodynamics, HS15, Master of Science in Engineering.

G.BOIGER, EVA Thermoﬂuiddynamik Modellentwicklung in OpenFoam 1, FS15, Master of Sci- ence in Engineering.

G.BOIGER, EVA Thermoﬂuiddynamik Modellentwicklung in OpenFoam 2, HS15, Master of Sci- ence in Engineering.

Zürcher Fachhochschule 47 www.zhaw.ch Institute of Computational Physics Research Report 2015

G.BOIGER, Heat and mass transfer with two-phase ﬂow, FS15, Master of Science in Engineering.

M.BONMARIN, Physik I für Systemtechnik, HS15, Bachelor of Science.

M.BONMARIN, Physik II für Maschinentechnik, FS15, Bachelor of Science.

M.BONMARIN, Physik I für Systemtechnik – Praktikum, HS15, Bachelor of Science.

M.BONMARIN, Physik II für Maschinentechnik – Pratktikum, FS15, Bachelor of Science.

T. HOCKER, Fluid- und Thermodynamik 1, FS15, Bachelor of Science.

T. HOCKER, Fluid- und Thermodynamik 2, HS15, Bachelor of Science.

T. HOCKER, Systemphysik für Aviatik 1 – Praktikum, HS15, Bachelor of Science.

M.JAZBINSEK, Numerik für Energie und Umwelttechnik – Praktikum, Bachelor of Science.

M.JAZBINSEK, Physik für Energie und Umwelttechnik 2, Bachelor of Science.

M.JAZBINSEK, Physik für Maschinentechnik 2, Bachelor of Science.

C.KIRSCH, Mathematik: Analysis für Ingenieure 4, FS15, Bachelor of Science.

C.KIRSCH, Mathematik: Lineare Algebra für Ingenieure 1, HS15, Bachelor of Science.

C.KIRSCH, Mathematik: Analysis für Ingenieure 3, 2HS15, Bachelor of Science.

C.MEIER,J.SCHUHMACHER, Brennstoffzellen und Verbrennung, HS15, Bachelor of Science.

K.PERNSTICH, Physik und Systemwissenschaft in Aviatik 1 – Praktikum, Bachelor of Science.

K.PERNSTICH, Physik und Systemwissenschaft in Aviatik 2 – Praktikum, Bachelor of Science.

J.SCHUMACHER, Analysis für Ingenieure HS15, Bachelor of Science.

J.SCHUMACHER, Physik 2 FS15, Bachelor of Science.

J.SCHUMACHER, Multiphysics Modelling and Simulation FS15, Master of Science in Engineering.

J.SCHUMACHER, Numerical Simulation of Solar Cells FS15, Master Online Photovoltaics.

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

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

www.zhaw.ch 48 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

Zürcher Fachhochschule 49 www.zhaw.ch Institute of Computational Physics Research Report 2015

A.10 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 where 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 support your product development cycle and to conform to yours time and budget constraints. 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 sup- ports 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 designed to simulate the 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 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 software in Switzerland and in addition we provide services such as consulting, training and software development.

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.

www.dermolockin.com

Dermolockin GmbH is a recently founded spin-off company developing active thermography-based setups for dermatological applications. The main focus lies in the detection and characterization of cutaneous cancerous lesions with lock-in thermal imaging methods.

www.zhaw.ch 50 Zürcher Fachhochschule Research Report 2015 Institute of Computational Physics

A.11 ICP-Team

Name Function e-Mail

Dr. Rebekka Axthelm Lecturer [email protected] Andor Bariska Research Assistant [email protected] Dr. Tilman Beierlein Research Assistant [email protected] David Bernhardsgrütter Research Assistant [email protected] Dr. Gernot Boiger Lecturer [email protected] Marlon Boldrini Research Assistant [email protected] Dr. Mathias Bonmarin Lecturer [email protected] Dr. Peter Cendula Research Associate [email protected] Teresa D’Onghia Administrative Assistant [email protected] Dr. Jaka Dujc Research Associate [email protected] Jonas Dunst Research Assistant [email protected] Josef Fuchs Research Assistant [email protected] Samuel Hauri Research Associate [email protected] Prof. Dr. Thomas Hocker Lecturer [email protected] Dr. Lorenz Holzer Research Associate [email protected] Dr. Mojca Jazbinsek Lecturer [email protected] Dr. Lukas Keller Research Associate [email protected] Dr. Christoph Kirsch Research Associate [email protected] Dr. Evelyne Knapp Research Associate [email protected] Kevin Lapagna Research Associate [email protected] Dr. Paolo Losio Research Associate [email protected] Philip Marmet Research Associate [email protected] Christoph Meier Research Associate [email protected] Martin Neukom Research Assistant [email protected] Tan Thai Nguyen Research Associate [email protected] Vit Orava Research Assistant [email protected] Tobias Ott Research Assistant [email protected] Omar Pecho Research Associate [email protected] Dr. Kurt Pernstich Lecturer [email protected] Markus Regnat Research Assistant [email protected] Prof. Dr. Nils Reinke Lecturer [email protected] Claude Ritschard Research Assistant [email protected] Prof. Dr. Beat Ruhstaller Lecturer [email protected] Benjamin Rutz Research Assistant [email protected] Dr. Yasser Safa Research Associate [email protected] Dr. Guido Sartoris Research Associate [email protected] Benjamin Schmid Research Assistant [email protected] Dr. Matthias Schmid Lecturer [email protected] Prof. Dr. Jürgen Schumacher Lecturer [email protected] Esther Spiess Administrative Assistant [email protected] Moreno Torroni Research Assistant [email protected] Urs Vögeli Research Assistant [email protected] Stephan Weilenmann Research Assistant [email protected] Dr. Andreas Witzig Lecturer, Head ICP [email protected] Simon Züﬂe Research Assistant simon.zueﬂ[email protected]

Zürcher Fachhochschule 51 www.zhaw.ch Institute of Computational Physics Research Report 2015

A.12 Location

ICP Institute of Computational Physics

Technikumstrasse 9 P.O. Box CH-8401 Winterthur www.icp.zhaw.ch

Contact Andreas Witzig Phone +41 58 934 45 73 [email protected]

Administration Esther Spiess Phone +41 58 934 73 38 [email protected] Teresa D’Onghia Phone +41 58 934 67 62 [email protected]

TK building TL building

www.zhaw.ch 52 Zürcher Fachhochschule

Zurich University of Applied Sciences School of Engineering

ICP Institute of Computational Physics

Technikumstrasse 9 P.O. Box CH-8401 Winterthur