Research on Next Generation Fuel Cell and Hydrogen Technologies
Due to current efforts being made in the reduction of greenhouse gas emissions and the associated political focus on hydrogen as a clean energy carrier, methods for sustainable hydrogen production and efficient utilization are again in great demand. In the coming years, fundamental and industry-related research as well as innovative ideas are essential to meet the ambitious goals with regard to efficiency, service life and sustainability of the whole process chain. The fuel cells and hydrogen working group is currently focusing on several approaches to tackle these challenges.
Wasserstoff – der Stromspeicher der Zukunft?
Soll unser Energiesystem umweltfreundlicher werden, so führt kein Weg an Wasserstoff als Energieträger vorbei. Dessen sind sich Forschende weltweit sicher. Rund 160 Wissenschafterinnen und Wissenschafter arbeiten an der TU Graz an Methoden der Erzeugung, Speicherung, des Transports und der Nutzung von Wasserstoff in mobilen, stationären und industriellen Anwendungen.
Katharina Kocher and Viktor Hacker
Polymer stabilization proved to be a promising approach to increase the catalytic performance of common platinum/carbon based cathode catalysts (Pt/C) used in polymer electrolyte membrane fuel cells (PEMFCs). Platinum and polyaniline composite catalysts (Pt/C/PANI) were prepared by combining chemical polymerization reactions with anion exchange reactions. Electrochemical ex‐situ characterizations of the decorated Pt/C/PANI catalysts show high catalytic activity toward the oxygen reduction reaction (ORR) and, more importantly, a significant enhanced durability compared to the undecorated Pt/C catalyst. Transmission electron microscopy (TEM) investigations reveal structural benefits of Pt/C/PANI for ORR catalysis. All studies confirm high potential of Pt/C/PANI for practical fuel cell application.
Figure: Illustration of Pt/C/PANI catalyst. ©TU Graz/CEET
ChemistryOpen (November 5, 2020)
The guest editors Prof. Katrašnik and Prof. Hacker invite you to submit articles for a special issue of Energies on “Development of Advanced Models for Analysis and Simulation of Fuel Cells”. To address the requirements on shorter product development cycles and reduced development costs, while boosting power density, efficiency, service life and safety, it is necessary to rely on advanced simulation models in the development process of fuel cells, their components, and fuel-cell-based systems. Simulation models are also indispensable for the analysis of fuel cells and for precise online monitoring.
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Patrick Krenn, Patrick Zimmermann, Michael Fischlschweiger and Tim Zeiner
The solvent absorption of an epoxy o-cresol novolac resin composite has been measured in different aqueous electrolyte solutions (NaCl, CaCl2 and MgCl2) at different salt concentrations from 0.1 to 0.3 mg/l. Next to the total solvent uptake, which was measured by a gravimetric measurement, the absorption of ions was determined by ion chromatography and by atomic absorption spectroscopy. The measured solvent absorption in equilibrium was calculated by combining the ePC-SAFT equation of state with a network term, which takes into account elastic forces in the polymer network counteracting a further solvent absorption. In order to model the solvent absorption kinetics, the equation of state was combined with a Maxwell-Stefan diffusion approach and the viscoelastic Kelvin-Voigt model for chain relaxation. The model parameters were only fitted to the absorption in pure water, what was only possible because the epoxy resin absorbed a neglectable amount of ions. The fully predictively calculated values for the absorption in electrolyte solutions are in qualitative agreement to the measured data.
Fluid Phase Equilibria, Volume 529, 1 February 2021, 112881
Internship abroad despite corona crisis: At Nedstack B.V. in Arnhem, the Netherlands, TU Graz student Niklas Mayr further developed analytical measurement methods for fuel cell research.
Here's his report:
In order to achieve the climate targets, the use of hydrogen is necessary. Numerous experts from industry and science agree on this. In recent years Graz has become a veritable hotspot for fuel cell and hydrogen research. We asked the top developers what makes hydrogen so interesting and why it can be a driver not only for climate protection but also for the economy.
Wirtschaftsnachrichten Süd, 10/2020, 54-57
Christoph Mayer and Thomas Wallek
In this paper, a model for two-component systems of six-sided dice in a simple cubic lattice is developed, based on a basic cluster approach previously proposed. The model represents a simplified picture of liquid mixtures of molecules with different interaction sites on their surfaces, where each interaction site can be assigned an individual energetic property to account for cooperative effects. Based on probabilities that characterize the sequential construction of the lattice using clusters, explicit expressions for the Shannon entropy, synonymously used as thermodynamic entropy, and the internal energy of the system are derived. The latter are used to formulate the Helmholtz free energy that is minimized to determine thermodynamic bulk properties of the system in equilibrium. The model is exemplarily applied to mixtures that contain distinct isomeric configurations of molecules, and the results are compared with the Monte-Carlo simulation results as a benchmark. The comparison shows that the model can be applied to distinguish between isomeric configurations, which suggests that it can be further developed towards an excess Gibbs-energy, respectively, activity coefficient model for chemical engineering applications.
Entropy 2020, 22(10), 1111;
Bernd Stoppacher, Robert Zacharias, Michael Lammer, Sebastian Bock, Karin Malli and Viktor Hacker
Der Reformer Steam Iron Cycle (RESC), eine Weiterentwicklung des Eisen-Dampf-Prozesses, bietet eine effiziente und kostengünstige Möglichkeit der dezentralen Wasserstoffherstellung. Das auf Reduktions- und Oxidationsreaktionen basierende Chemical Looping System ist in der Lage, hochreinen Wasserstoff aus Biogas, vergaster Biomasse und gasförmigen Kohlenwasserstoffen zu erzeugen. Da eine Reinheit von > 99.999 % bereits im RESC Prozess erreicht wird, sind im Gegensatz zu konventionellen Verfahren, wie Dampfreformierung oder autotherme Reformierung, keine weiteren Reinigungsschritte im System notwendig. Zudem kann das System, durch Abscheidung von hochreinem Stickstoff und Kohlenstoffdioxid, wertvolle Nebenprodukte erzeugen und als Negativemissionstechnologie betrieben werden.
The Reformer Steam Iron Cycle (RESC), a further development of the iron-steam process, offers an efficient and cost-effective option for decentralized hydrogen production. The chemical looping system based on reduction and oxidation reactions is capable of producing high-purity hydrogen from biogas, gasified biomass and gaseous hydrocarbons. Since a purity of > 99.999 % is already achieved in the RESC process, no further purification steps are necessary in the system, in contrast to conventional processes such as steam or autothermal reforming. In addition, the system can generate valuable by-products by separating high purity nitrogen and carbon dioxide and can be operated as a negative emission technology.
gwf Gas+Energie, 09/2020, ISSN 2366-9594, Seite 62-69
M. Mohsin, R. Raza, M. Mohsin-ul-Mulk, A. Yousaf, V. Hacker
In this paper the diagnostic results of single polymer electrolyte membrane fuel cell assemblies are presented, which are characterized by polarization curves. Single PEM fuel cell assemblies were investigated by accelerated voltage cycling tests at different humidity levels. The cells are discussed in this paper with analysis results at different humidity values and different atmospheric pressures. The decrease in relative humidity can result in slower electrode kinetics, including electrode reaction and mass diffusion rates, and higher membrane resistance.
International Journal of Hydrogen Energy, Volume 45, Issue 45, 24093-24107.
Paul Demmelmayer, Julio Hilgert, Robby Wijaya, and Marlene Kienberger
Crud formation during reactive extraction hinders phase separation and makes the application of conventional extraction equipment more challenging. This study investigates the influence of amines as a reactive extractant, pH value, and temperature on the crud formation and extraction efficiency for the reactive extraction of lignosulfonates from the Ca–lignosulfonate model solution and spent sulfite liquor. The overall extraction efficiency for different amines dissolved in 1-octanol increased in the order quaternary < tertiary < secondary < primary amines for both the model solution and the spent liquor. Phase equilibria for dioctylamine and trioctylamine showed that the temperature increase from 25 to 50 °C had no effect on the extraction efficiency but clearly reduced the crud formation in the extraction step. No crud was observed during back extraction into deionized water, 0.3 M NaOH, or 0.3 M NaHCO3. The pH value highly influences the phase equilibrium; the extraction step has to be performed at low pH values and the back extraction step at high pH values.
Ind. Eng. Chem. Res. 2020, 59, 37, 16420–16426
Tobias Grubinger, Georg Lenk, Nikolai Schubert and Thomas Wallek
Fuel surrogates are substitute mixtures that are developed to reproduce real fuels’ physical and chemical properties. These mixtures are created with a small number of components, considering their application in various types of simulations and for bench tests. In the present paper, new gasoline surrogates are proposed by extending and applying an algorithm which was previously developed and successfully used to create diesel surrogates.
The five target properties chosen for surrogate optimization include the true boiling point curve (TBP), the research octane number (RON), the liquid density, the carbon-to-hydrogen (C/H) ratio and the oxygenate content.
The algorithm is applied to three target fuels, comprising two reference fuels from the FACE working group and one typical oxygenated gasoline that is commercially available in Europe. The proposed surrogates consist of six chemical components which are also represented in reaction kinetics for fuel combustion. An experimental comparison of the boiling point curves, densities and RONs among the surrogates and their respective target fuels provided evidence that the proposed surrogates excellently reproduce the real fuels' properties.
Fuel, Volume 283, 1 January 2021, 118642