55 research outputs found
The CellFlux storage concept for cost reduction in parabolic trough solar thermal power plants
No full textAlthough facility scale thermal energy storage of sensible heat in the range of 200-600°C has achieved a high maturity, state-of-the-art approaches are still not very cost effective. An innovative storage concept is thus proposed here that avoids the two major cost-driving factors of the concrete storage and 2-tank molten salt systems. First, the storage volume is comprised of low-cost sensible storage material such as concrete, natural stone or clinker bricks. These materials are several times cheaper than eutectic salt mixtures used in the 2-tank-storage system. Secondly, the system uses an intermediate air cycle, allowing for direct contact with the storage material. The necessary heat exchanger for transferring the heat from the primary oil loop to the intermediate air cycle consists of significantly less steel compared to the tube register inside the concrete storage. All components are kept in close proximity inside an enclosed loop, thus avoiding long flow lengths and keeping parasitic losses within a reasonable range.
Preliminary investigations have shown that the overall performance and profitability of the storage system are closely linked to the thermal efficiency and pressure drop of the heat exchanger, the effectiveness of the storage, as well as the operation strategy. To demonstrate the feasibility of the storage concept and to investigate its performance characteristic under realistic conditions, a pilot scale test facility has been set up. In parallel, dynamic models of the storage system and a SEGS-like solar thermal power plant have been implemented in a Matlab/Simulink environment to analyze its performance theoretically. Experimental data is also used for model validation.
The conference presentation gives a detailed overview of potential configurations and their dynamic behavior. Furthermore, first experimental results of the demonstration facility are presented
Advanced high temperature latent heat storage system - design and test results
No full textProcesses with a two-phase heat transfer fluid (e.g. water/steam) require isothermal energy storage. Latent heat storage systems are an option to fulfil this demand. For high temperature applications nitrate salts are suitable materials for phase change storage. The main drawback of these materials is the low thermal conductivity, limiting the power density during the charging/discharging process. At DLR the so called sandwich-concept has been developed to realize latent heat storage with high power densities for applications in solar thermal power plants and process industry. This concept has already been demonstrated successfully for three different storage units ranging from 2-100 kW at melting temperatures of 142 °C and 222 °C. In 2008, a test storage using sodium nitrate as phase change material (PCM) with a melting temperature of 306 °C was operated in a 5 kW laboratory loop. The designed heat transfer rate was achieved and after 172 cycles no degradation was observed
Fährten – Gefährten. Making Friends:Wolf Suschitzkys Tierfotografien im Prisma des Exils
No full textWolf Suschitzky wollte ursprünglich in Wien Zoologie studieren, entschied sich dann, angeregt von seiner Schwester Edith Tudor-Hart, für die Fotografie und brachte sein zoologisches Interesse in die Fotografie ein. Suschitzky floh 1934 mit 22 Jahren aus Wien zunächst nach Holland, ging dann nach London, wo er ab 1936 im Londoner Zoo als Assistent des britischen Filmdirektors Paul Rotha arbeitete. Bei ihm lernte Suschitzky neue Kameratechniken. Er durfte bei eigenen Fotoaufnahmen von Tieren direkt in den ‘enclosures’ arbeiten, was ihm ermöglichte, eindrucksvolle Nahaufnahmen zu machen.Ab 1938 erschienen seine Tieraufnahmen in britischen Revues (z.B. Animal and Zoo Magazine und Geographical Magazine), Kinderbüchern (z.B. The Children’s Zoo, 1939) und praktischen Fotobüchern, (z.B. Photographing Animals,1941, mit einem Vorwort des Zoologen Julian Huxley).Suschitzkys Tieraufnahmen veränderten den Blick der Öffentlichkeit auf Tiere, besonders auch auf die Zootiere und die Tatsache ihrer Gefangenschaft. Er stellte sie als eigenständige Wesen dar, denen man mit dem selben Respekt wie Menschen begegnen müsse.An ausgewählten Beispielen wie Guy the Gorilla, wird gezeigt, dass Suschitzky in seinen Bildern den Widerspruch zwischen Autonomie und Gefangenschaft, zwischen Leben in der Natur und der Präsentation hinter vergitterten Käfigen im Zoo thematisiert.Das Verhältnis von Mensch und Tier, Nähe und Ferne wird neu austariert und damit die Vorstellung des Exotischen, das für das Verständnis wilder Tiere und ihrer Präsentation im Zoo historisch bestimmend war, unterlaufen
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