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Session: Volumetric expanders III
Session starts: Tuesday 08 October, 11:20
Presentation starts: 11:20
Room: Van Beuningen Zaal

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Florian Götz (Fraunhofer ICT/IWM Projectgroup NAS)
Stefan Hess (Fraunhofer ICT/IWM Projectgroup NAS)
Hans-Peter Kollmeier, Dr. (Fraunhofer ICT/IWM Projectgroup NAS)

Abstract:
ABSTRACT In a combustion engine about one third of the chemical energy of fuel is converted into mechanical energy. About two thirds of the fuel energy dissipates unused with exhaust gas and cooling water [1]. Waste heat recovery offers possibilities to use this thermal energy. One way to recover heat is the (Organic) Rankine Cycle [2]. One of the key elements of this cycle is the expansion device. Hence the research and development of these machines are of great interest to achieve a high efficiency in waste heat recovery applications. In this paper the use of precise pressure indication, with piezoelectric and piezoresistive transducers, is analyzed. While the measurement technique is well established within engine test benches for combustion engines it is new to expansion devices [3]. Deviating boundary conditions are the key factor to look at for precise and reliable measurements. Furthermore error sources such as the determination of the top dead centre are examined. After evaluation and assimilation of the most important parameters the precise pressure indication is tested in two expansion devices. A rotary-piston and an axial-piston expansion-device are put to test. Based on the results of the analysis, carried out with the measurements of the devices, possibilities and benefits of precise pressure indication of expansion devices are presented. Finally a comparison of the ideal reference cycle is carried out to evaluate the potential of each machine. REFERENCES [1] Horenburg, Peter: Abwärme zu Strom veredeln; BINE-Projektinfo 13/2011, Bundesministerium für Wirtschaft und Technologie (BMWi); FIZ Karlsruhe GmbH [2] Rohloff, Kathrin; Kather, Alfons: Geothermische Stromerzeugung, Kraftwerkstechnologien und Technologien zur gekoppelten Erzeugung von Strom und Wärme; Mai 2011, Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit (BMU), Referat Öffentlichkeitsarbeit, 11055 Berlin [3] Teichmann, Rüdiger; Schwarz, Christian; Wimmer, Andreas; Winklhofer, Ernst: Verbrennungsdiagnostik. Sonderdruck, Springer Vieweg, Graz 2012