@article{GoettscheHoffschmidtSchmitzetal.2010,
  author    = {G{\"o}ttsche, Joachim and Hoffschmidt, Bernhard and Schmitz, Stefan and Sauerborn, Markus},
  title     = {Solar Concentrating Systems Using Small Mirror Arrays},
  series = {Journal of solar energy engineering},
  volume    = {132},
  journal   = {Journal of solar energy engineering},
  number    = {1},
  publisher = {ASME},
  address   = {New York},
  issn      = {0199-6231},
  doi       = {10.1115/1.4000332},
  pages     = {4 Seiten},
  year      = {2010},
  abstract  = {The cost of solar tower power plants is dominated by the heliostat field making up roughly 50\% of investment costs. Classical heliostat design is dominated by mirrors brought into position by steel structures and drives that guarantee high accuracies under wind loads and thermal stress situations. A large fraction of costs is caused by the stiffness requirements of the steel structure, typically resulting in ~ 20 kg/m² steel per mirror area. The typical cost figure of heliostats (figure mentioned by Solucar at Solar Paces Conference, Seville, 2006) is currently in the area of 150 €/m² caused by the increasing price of the necessary raw materials. An interesting option to reduce costs lies in a heliostat design where all moving parts are protected from wind loads. In this way, drives and mechanical layout may be kept less robust, thereby reducing material input and costs. In order to keep the heliostat at an appropriate size, small mirrors (around 10x10 cm²) have to be used, which are placed in a box with a transparent cover. Innovative drive systems are developed in order to obtain a cost-effective design. A 0,5x0,5 m² demonstration unit will be constructed. Tests of the unit are carried out with a high-precision artificial sun unit that imitates the sun's path with an accuracy of less than 0.5 mrad and creates a beam of parallel light with a divergence of less than 4 mrad.},
  language  = {en}
}
@article{GeimerSauerbornHoffschmidtetal.2010,
  author    = {Geimer, Konstantin and Sauerborn, Markus and Hoffschmidt, Bernhard and Schmitz, Mark and G{\"o}ttsche, Joachim},
  title     = {Test facility for absorber specimens of solar tower power plants},
  series = {Advances in Science and Technology},
  volume    = {74},
  journal   = {Advances in Science and Technology},
  publisher = {Trans Tech Publications},
  address   = {Baech},
  doi       = {10.4028/www.scientific.net/AST.74.266},
  pages     = {266 -- 271},
  year      = {2010},
  abstract  = {The Solar-Institute J{\"u}lich (SIJ) has initiated the construction of the first and only German solar tower power plant and is now involved in the accompanying research. The power plant for experimental and demonstration purposes in the town of J{\"u}lich started supplying electric energy in the beginning of 2008. The central receiver plant features as central innovation an open volumetric receiver, consisting of porous ceramic elements that simultaneously absorb the concentrated sunlight and transfer the heat to ambient air passing through the pores so that an average temperature of 680°C is reached. The subsequent steam cycle generates up to 1.5 MWe. A main field of research at the SIJ is the optimization of the absorber structures. To analyze the capability of new absorber specimens a special test facility was developed and set up in the laboratory. A high-performance near-infrared radiator offers for single test samples a variable and repeatable beam with a power of up to 320 kW/m² peak. The temperatures achieved on the absorber surface can reach more than 1000°C. To suck ambient air through the open absorber - like on the tower - it is mounted on a special blower system. An overview about the test facility and some recent results will be presented.},
  language  = {en}
}