Institute for Energy Systems and Thermodynamics

Vienna, Austria

Institute for Energy Systems and Thermodynamics

Vienna, Austria
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Krejci D.,Fotec GmbH | Woschnak A.,Fotec GmbH | Schiebl M.,University of Applied Sciences Wiener Neustadt | Scharlemann C.,University of Applied Sciences Wiener Neustadt | And 8 more authors.
Journal of Propulsion and Power | Year: 2013

Hydrogen peroxide is a candidate propellant for rocket-propulsion applications with the potential to replace highly toxic propellants currently used. Decomposition of hydrogen peroxide yields a high-temperature oxygen-steam mixture, which can be used as monopropellant or as oxidizer in a bipropellant configuration. This work examines different types of cellular ceramic-based catalysts for hydrogen-peroxide decomposition at miniature scale of nominal mass flows of 0.3 gs-1. An exhaustive investigation of different catalysts in a flow reactor configuration similar to a propulsion application is conducted. The test matrix includes honeycomb monoliths with different channel geometries, densities, lengths, different carrier materials, and wash-coating procedures, as well as different types of catalysts such as pellets and foams. Thirty nine catalyst configurations with a total of 121 catalysts have been experimentally investigated based on their transient and stationary performance at design mass-flow levels of 0.3 gs-1. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc.

Brunauer G.C.,Institute for Energy Systems and Thermodynamics | Brunauer G.C.,NOVAPECC GmbH | Rotter B.,Institute for Energy Systems and Thermodynamics | Walch G.,Institute of Chemical Technologies and Analytics | And 5 more authors.
Advanced Functional Materials | Year: 2016

A solid-state photoelectrochemical cell is operated between 400 and 500°C under 365 nm UV light. The cell consists of a photovoltaic part, based on a La0.8Sr0.2CrO3/SrTiO3 junction, and an electrochemical part including a zirconia solid electrolyte with a shared (La,Sr)FeO3 electrode. The photovoltaic cell part leads to open circuit voltages up to 920 mV at 400°C. Upon UV light, this driving force is used in the electrochemical part of the cell to pump oxygen from low to high partial pressures, i.e., to convert radiation energy to chemical energy. This demonstrates the feasibility of high-temperature photoelectrochemical cells for solar energy storage. The detailed characterization of the different resistance contributions in the system by DC and AC methods reveals the parts of the cell to be optimized for finally achieving high-temperature photoelectrochemical water splitting. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

News Article | April 27, 2016

I have written about a few different floating solar projects recently. These floating platform-based power plants are ideal for countries that don't have much land to spare for large solar farms. They can be built over ponds, lakes and reservoirs and help to prevent water evaporation and algae overgrowth. Floating solar panels seem to be catching on, but there is one place for which they haven't seemed well-suited: the ocean. As with any technology that dares to reside in the rough environment of the sea -- offshore wind turbines, wave power buoys, etc. -- building something that is both tough enough to withstand harsh conditions and light and flexible enough to be effective (and not totally cost-prohibitive) is very tricky. Researchers at the Vienna University of Technology think they have developed just the right combo with their Heliofloat concept. These floating solar platforms meant for any body of water including the ocean, are lightweight and flexible enough to bob with the waves while remaining steady on the surface, even in rough weather. The key to this, the researchers say, is that the bottom is supported with open floatation devices as opposed to closed ones. "Were a platform to be simply mounted onto air-filled, closed containers, the design of the construction would have to be inefficiently heavy and robust in order to be able to withstand heavy waves," said explains Professor Markus Haider, from the Institute for Energy Systems and Thermodynamics. The floats look like upside-down barrels made out of a flexible material. The barrels create a column of air over the water that allows the platform to float and also acts as a shock absorber, while the soft material of the barrels absorb small, horizontal forces. The result of this is that the waves rise and fall beneath the platform while the platform itself stays steady above the water. A closed air floatation device would absorb so much of the wave energy that the platform would ultimately break. The researchers believe that this design would allow floating solar installations the size of football fields to grace the coast of countries that don't have the land to spare for large solar power projects or over lakes where water evaporation is a problem. In addition, the Heliofloats could be used in sea water desalination plants in areas that need more clean water. A very small-scale prototype will be unveiled at the Hannover Messe trade fair and the researchers are in discussions with investors to produce large-scale versions.

Adjassoho B.,Institute of Materials Science and Technology | Kozeschnik E.,Institute of Materials Science and Technology | Lechner C.,Institute for Production Engineering and Laser Technology | Habersohn C.,Institute for Production Engineering and Laser Technology | And 6 more authors.
METAL 2013 - 22nd International Conference on Metallurgy and Materials, Conference Proceedings | Year: 2013

Machine Hammer Peening (MHP) it is a cold deformation process with the aim of improving the condition of the upper surface layer of metal work pieces. The process is carried out by an actuator, which can be mounted on conventional machining tools. A vertical guide, oscillating plunger, with a spherical carbide tool can perform well-directed hits on the work piece surface. The authors of this paper have investigated the effect of MHP on the materials microstructure and the mechanical characteristics of different machine hammer peened work pieces. The microstructure of the steel X3CrNiMo13-4 was investigated in peening direction, normal to it as well as diagonally. Nano-hardness measurements on X3CrNiMo13-4 were carried out to see if the MHP process has a significant influence on the results of the hardness measurements. Because of the fact that MHP creates a "valley and hill" like morphology in the range of some μm on the surface, the question arises whether there is a significant difference between the hardness measured in the valley or on the hill. Another mechanical characteristic, which can be influenced by the MHP process, is the induction of residual stress. Therefore, measurements with the hole drilling method on the material X3CrNiMo13-4 were done to see how compressive residual stress can be induced by MHP. © 2013 TANGER Ltd., Ostrava..

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