In Concentrated Solar Power (CSP) plants the incident solar radiation is focused onto a receiver by means of collectors. A fluid is heated up and in a downstream power block electricity is generated. In point-focusing solar towers, the solar concentration is achieved by so-called heliostats that are arranged to a solar field. In this contribution, the development of concrete heliostats with circular shapes and an aperture area of 30 m 2 is presented. A high-performance concrete with high tensile and compressive strength values is used. The circular structure is dissolved into identical but symmetrically reduced modules derived from system reduction methods. For designing, the tensile strength of the concrete is restrictive to ensure linear-elastic material behavior and to avoid softening by cracking. After dimensioning, the derived equivalent plate is converted into strut-like structures possessing equal stiffnesses with respect to the partial module size. These modules are circularly post-tensioned to form a heliostat. Numerical investigations of the modules prove their accuracy. A full solar concentration, that is, the reflected solar radiation is completely focused on the receiver, is achieved. Due to the multitude of modules within a solar field, serial production with integrated quality control is recommended.
Parabolrinnen sind die etablierteste Technologie konzentrierender solarthermischer Kraftwerke, welche die direkte solare Strahlung linienartig zur nachträglichen Stromerzeugung mittels Kraftwerksblock bündeln (Concentrated Solar Power). Bisherige Kollektoren bestehen überwiegend aus Stahlfachwerken, die parabolisch gekrümmte Spiegel punktartig stützen. Dabei entsteht eine Trennung von Trag‐ und Reflektorstruktur. Diese Separation wurde durch eine Betonschale mit einem kleinformatigen Demonstrator aus Hochleistungsbeton mit neuartiger Abrolllagerung aufgehoben [3]. Im Projekt ConSol („Concrete Solar Collector“) wurde von einem Konsortium unter Führung des Deutschen Zentrums für Luft‐ und Raumfahrt (DLR) dieses konzeptionelle Design aufgegriffen und auf originalmaßstäbliche Parabolrinnen mit einer Aperturweite von 5,77 m und einer Gesamtlänge von 24 m weiterentwickelt. Dazu wurde eine verformungsoptimierte, filigrane Betonschale von nur i. M. 4,5 cm Dicke entwickelt, welche auf einer sichelförmigen Abrolllagerung der Sonne nachgeführt wird. Ein Kippen bzw. Abrutschen wird durch Betonverzahnungen verhindert. Die Nachführung gelingt über ein eigens entwickeltes Antriebssystem mit Kettenverbindungen und einer Leistung von nur 180 W. Eine Qualifizierung der optischen Wirksamkeit erfolgte mithilfe digitaler Nahbereichsphotogrammetrie.
The advancing digitalization is changing almost all areas of society and drives rapid innovation. The construction industry provides many fields of application with numerous opportunities for improvement of efficiency. Accordingly, there are chances and threats caused by digital change at present. The main challenge is the extreme wide range of topics and tasks in all phases of the value chain-development, design, construction, and operation-concerning hardware and software. The aim of this study is to evaluate, if digital sensors can be helpful for an enhanced construction. In a first study for an application field, the authors pointed out the moisture content of structures, because this is a comparatively clear but also crucial point in construction process. In specific, a new digital sensor system for the moisture measurement in screed is being developed and evaluated. The achieved results show general feasibility of digital sensors to improve the construction process and motivate for further studies in this research field.
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