3-2. Space Power Thermal Energy Storage: Planned Experiments for Phase Change Material Tests in Microgravity S. WEINGARTNER, J. BLUMENBERG & F. LINDNER Summary A heat of fusion thermal energy storage (TES) unit as part of a solar dynamic space power system is probably the best choice to provide continuous power during the eclipsed portion of the orbit. The usual high volume contraction peculiar to the phase change of relevant high-temperature storage media aggravates the receiver/storage unit design. Several experiments are planned to study the melting/solidification processes of relevant storage media in weightlessness. This paper gives an overview of drop tower experiments (scheduled for the end of 1989), ballistic flight experiments (scheduled for early 1991) and a Spacelab experiment (D2-mission, scheduled for December 1991). It then presents status and results of preparations in progress and discusses problems with and solutions for future experiments and future TES applications in space. The ratio profit (results)/costs to be expected was very similar for all three types of microgravity experiments. Companies involved in this research are the Technical University Munich, the Deutsche Forschungs- und Versuchsanstalt fur Luftund Raumfahrt (DFVLR; German Research Institute for Aeronautics and Astronautics), Stuttgart; and Messerschmitt- Bblkow-Blohm (MBB), all of the Federal Republic of Germany. Introduction Solar dynamic power systems are competitive with photovoltaic systems if high power levels in low earth orbits (LEO) are required, e.g. with regard to the power demands of the international space station Freedom [1]. A schematic for a solar dynamic power system is shown in Fig. 1. Thermal energy storage (TES) integrated with the receiver (REC) is one of the key elements of such a thermodynamic system. In contrast to electrical or mechanical storage systems the TES enables the power conversion unit (PCU) to run continuously during the whole orbit and hence reduces the mass and considerably increases the lifetime of the PCU. The REC/TES unit has to transform the intermittent sunlight into a constant heat output. The heat energy transferred to the PCU should Dipl.-Phys. Stefan Weingartner, Lehrstuhl fur Raumfahrttechnik, Technische Universitat Munchen, FRG; Dr.-Ing. Itirgen Blumenberg, Lehrstuhl C fur Thermodynamik, Technische Universitat Munchen, FRG; Dr.- Ing. Friedrich Lindner, Institut fur Technische Thermodynamik, Deutsche Forschungs- und Versuchsanstalt fur Luft- und Raumfahrt (DFVLR), Stuttgart, FRG. Paper number IAF-ICOSP89-3-2.
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