Research Outputs

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Now showing 1 - 10 of 20
  • Publication
    Radiation Shielding Using Micro Cavities Filled with Highly Pressurised Gas
    (2012-11-29)
    Usually, hydrogen is stored under high pressure, in chemical compounds or in its liquid state requiring very low temperatures. Gaseous hydrogen can be stored in hollow glass microspheres (5 μm to 200μm diameters) under high pressure (350 bar to 700 bar). The sphere-wall is impermeable for hydrogen at ambient temperature; the heating of the spheres increases the diffusion of hydrogen through the wall. The Aerospace Engineering group of the FOTEC GmbH developed an innovative process for the European Space Agency that combines the storage concepts of hollow glass microspheres with chemical hydrogen storage. The combination of these two principles provides the advantages of both but cancels their respective drawbacks. Our analysis shows that such a system can reach hydrogen storage capacities of up to 10wt% in theory. This value depends on the sphere dimensions, the weight of the spheres, the hydrogen pressure, and the nature of the utilised hydride. The expertise gained in the course of the extensive research on gas storage in hollow microspheres lead to new applications for such a system. One of these applications is the use of microspheres filled with highly pressurized gas as radiation shielding material. Since hydrogen is very effective in absorbing the energy of highly energetic particles with minimal generation of secondary particles, it is particularly suitable for radiation shielding. Effective radiation shielding materials therefore often incorporate high concentrations of hydrogen. By using glass microspheres, it becomes possible to collect large amounts of hydrogen atoms with a relatively high gravimetric as well as volumetric density. It is also possible to store other light gases in the microspheres like deuterium or helium, in order to customize the absorption properties of the material. Preliminary calculations show that this technique can be used as radiation shielding with significant mass savings in respect to conventional materials. In comparison to aluminium for example, the hydrogen filled microspheres can shield high-energy protons and ions with 30% to 40 % increased efficiency. Also bremsstrahlung, secondary neutrons and gamma rays can be significantly reduced. Due to the fact that the material can be easily adapted to any given form, the possible terrestrial applications include: radiation shielding of aircrafts, shielding of computer and electronics, radiation shielding in research facilities as well as on medical sites, but also protective clothing for PCRs (Competent Person in Radioprotection). Considering the possibility to produce large amounts of such a material with relatively low cost, a broad industrial interest for such a light-weight and ultra-dense radiation shielding material can be expected. Also, the considered material is easy to handle with respect to safety and flexibility. Space technology could be used to protect the environment and the population against radiation. To make this technology available for terrestrial applications, the first step is the detailed assessment of the physical processes of gas-filled microspheres in a radioactive environment. It is then possible to investigate the best combination of gas species, microsphere properties, coating layer and support structure or binding material for different applications. The second step is the production of a prototype layer material based on filled microspheres and the testing of the radiation shielding properties of the new material. The Aerospace Engineering group is specialised in the development of micro propulsion and gas storage systems for space application. It has a long record of successful projects performed on behalf of the European Space Agency. As research and service provider of the University of Applied Sciences Wiener Neustadt, it is the ideal hub for educational, industrial and scientific projects. A test facility to test the catalyst efficiency and the thermal properties of the coated microspheres as well as filling the microspheres with different gases is available.
      96
  • Publication
    Development of a Ti-doped Sodium Alanate Hydrogen Storage System
    (2009) ;
    Reissner, Alexander 
    ;
    Dudzinski, Piotr 
    ;
    Tajmar, Martin 
    A trade-off analysis regarding power supply on satellites, which was performed for the European Space Agency (ESA), suggested that fuel cells might be an interesting candidate to replace secondary batteries on satellites. The Austrian Research Centers (ARC) decided to approach this topic by combining a fuel cell with innovative chemical hydrogen and oxygen storage as well as integrating the oxygen storage system into a form that can be used as a structural element. Also an integration of the fuel cell into the hydrogen tank, and the resulting storage of dissipation heat, results in a reduction of the necessary thermal control system. These advantages are very interesting in order to obtain higher weight efficiencies, which are especially important for space and automotive applications. The complete system includes a hydrogen storage tank based on Ti-doped sodium alanate and a novel oxygen tank based on YBaCo4O7 developed at ARC. Water tanks and a micro-fluidic system connected to the fuel cell have been considered as well in order to provide a completely reversible system, competitive to batteries. For the hydrogen storage, a finite elements model has been developed, implementing the reaction kinetics of the storage process, in order to predict the thermal mechanisms during adsorption and desorption of hydrogen in sodium alanate. The present paper discusses these simulations, the development of an experimental hydrogen storage tank and the proposed concepts of a battery replacement system.
      97
  • Publication
    Metal Hydrides as Hydrogen and Heat Storage System for Satellite Applications
    (2013-06-16)
    Reissner, Alexander 
    ;
    ;
    Hummel, Stefan 
    ;
    Scharlemann, Carsten 
    ;
    Tajmar, Martin 
      122  1
  • Publication
    Novel Hydrogen Storage Solutions for Space and Aerospace Applications
    (2011-05-15) ;
    Reissner, A. 
    ;
    Bichler, D. 
    ;
    Tajmar, M. 
    Novel hydrogen storage solutions are increasingly important for a number of future aerospace and space applications. The Aerospace Engineering Group of the fotec Forschungs- und Technologietransfer GmbH is presently developing an innovative hydrogen storage system based on high pressure hydrogen storage in microspheres. The hollow glass microspheres are loaded with up to 700 bar of hydrogen gas with a thermal process. The gas was released with a special heating wire. Such a system could be used as safety gas generator on satellites and airplanes. An additional space application for hydrogen filled microspheres seemed to be the use as additive in cryogenic liquid storage systems to enlarge the longtime durability. Further projects deals with new energy storage solutions to replace secondary batteries on satellites. We decided to approach this topic by directly coupling a fuel cell with a metal hydride based on Ti-doped sodium alanate. The power dissipation of the fuel cell can be used for desorption of hydrogen where heat is required, instead of being rejected by a heavy thermal control system. This advantage would be very interesting in order to obtain higher weight efficiencies which are especially important for space and submarine applications.
      197  530
  • Patent
      220  210
  • Publication
    Innovative Hydrogen Storage in Hollow Glass-Microspheres
    (2009) ;
    Schmid, G. 
    ;
    Tajmar, Martin 
      84
  • Publication
    Neutron transmission measurements on hydrogen filled microspheres
    (Elsevier, 2013-10-26)
    Dyrnjaja, Eva 
    ;
    Hummel, Stefan 
    ;
    ;
    Smolle, Marie-Theres 
    ;
    Gerger, Joachim 
    ;
    Zawiswky, Michael 
    Hollow microspheres are promising candidates for future hydrogen storage technologies. Although the physical process for hydrogen diffusion through glass is well understood, measurements of static quantities (e.q. hydrogen pressure inside the spheres) as well as dynamic properties (e.g. diffusion rate of hydrogen through glass) are still difficult to handle due to the small size of the spheres (d ! 15 lm). For diffusion rate measurements, the long-term stability of the experiment is also mandatory due to the relatively slow diffusion rate. In this work, we present an accurate and long-term stable measurement technique for static and dynamic properties, using neutron radiography. Furthermore, possible applications for hydrogen filled microspheres within the scope of radiation issues are discussed.
      65Scopus© Citations 1
  • Publication
    Characterization of the Reversible Hydrogenation Properties of Sodium Alanate under various contaminated Hydrogen Conditions
    (2013-06-17)
    Reissner, Alexander 
    ;
    ;
    Hummel, Stefan 
    ;
    Scharlemann, Carsten 
    ;
    Tajmar, Martin 
      122
  • Publication
    Development of Innovative Micro Power Converter Technologies at the Austrian Institute of Technology
    (American Institute of Aeronautics and Astronautics, 2009-08) ;
    Vasiljevich, Ivanhoe 
    ;
    Dudzinski, Piotr 
    ;
    Tajmar, Martin 
    ;
    Gerger, Joachim 
    Waste heat is a primary source of energy loss in many aerospace and terrestrial applications. The Austrian Institute of Technology (AIT) is presently developing two different types of micro power converters, promising high efficiencies in their respective application areas. The first converter is based on an innovative thermoacoustic Stirling engine concept without moving parts. Such a maintenance-free engine system would be particularly suitable for advanced Stirling radioisotope space power systems. The second converter is based on microturbines to use exhaust-gases for improving the overall efficiency for a number of applications. This paper will summarize our efforts on micro power converter technologies.
      104Scopus© Citations 1