@article{BuckFaberMelissetal.1995,
  author    = {Buck, H. and Faber, Christian and Meliß, Michael and Schwarzer, Klemens},
  title     = {Aus- und Weiterbildung am Solar-Institut J{\"u}lich},
  series = {Energie f{\"u}r die Zukunft : 28. Juni bis 1. Juli 1994 ; [Tagungsbericht 2] / 9. Internationales Sonnenforum '94. [Hrsg. Deutsche Gesellschaft f{\"u}r Sonnenenergie e.V. - DGS. Red. A. Hohmann ; H. H. Hohmann]. - (Internationales Sonnenforum ; 9,2)},
  journal   = {Energie f{\"u}r die Zukunft : 28. Juni bis 1. Juli 1994 ; [Tagungsbericht 2] / 9. Internationales Sonnenforum '94. [Hrsg. Deutsche Gesellschaft f{\"u}r Sonnenenergie e.V. - DGS. Red. A. Hohmann ; H. H. Hohmann]. - (Internationales Sonnenforum ; 9,2)},
  publisher = {DGS-Sonnenenergie},
  address   = {M{\"u}nchen},
  pages     = {1779 -- 1785},
  year      = {1995},
  language  = {de}
}
@article{BlankeRegerDoeringetal.2021,
  author    = {Blanke, Tobias and Reger, Vitali and D{\"o}ring, Bernd and G{\"o}ttsche, Joachim and Kuhnhenne, Markus},
  title     = {Koaxiale Stahlenergiepf{\"a}hle},
  series = {Stahlbau},
  volume    = {90. 2021},
  journal   = {Stahlbau},
  number    = {6},
  publisher = {Wiley},
  address   = {Weinheim},
  pages     = {417 -- 424},
  year      = {2021},
  abstract  = {Ein entscheidender Teil der Energiewende ist die W{\"a}rmewende im Geb{\"a}udesektor. Ein Schl{\"u}sselelement sind hier W{\"a}rmepumpen. Diese ben{\"o}tigen eine W{\"a}rmequelle, der sie Energie entziehen k{\"o}nnen, um sie auf ein h{\"o}heres Temperaturniveau zu transformieren. Diese W{\"a}rmequelle kann bspw. das Erdreich sein, dessen W{\"a}rme durch Erdsonden erschlossen werden kann. In diesem Beitrag werden in Stahlpf{\"a}hle integrierte Koaxialsonden mit dem Stand der Technik von Erdsonden gleichen Durchmessers bez{\"u}glich ihrer thermischen Leistungsmerkmale verglichen. Die Stahlenergiepf{\"a}hle bieten neben der W{\"a}rmegewinnung weitere Vorteile, da sie auch eine statische Funktion {\"u}bernehmen und r{\"u}ckstandsfrei zur{\"u}ckgebaut werden k{\"o}nnen. Es werden analytische und numerische Berechnungen vorgestellt, um die thermischen Potenziale beider Systeme zu vergleichen. Außerdem wird ein Testaufbau gezeigt, bei dem Stahlenergiepf{\"a}hle in zwei verschiedenen L{\"a}ngen mit vorhandenen g{\"a}ngigen Erdsonden verglichen werden k{\"o}nnen. Die Berechnungen zeigen einen deutlichen thermischen Mehrertrag zwischen 26 \% und 148 \% der Stahlenergiepf{\"a}hle gegen{\"u}ber dem Stand der Technik abh{\"a}ngig vom Erdreich. Die Messergebnisse zeigen einen thermischen Mehrertrag von {\"u}ber 100 \%. Es l{\"a}sst sich also signifikante Erdsondenl{\"a}nge einsparen. Dabei ist zu beachten, dass sich damit der thermisch genutzte Bereich des Erdreichs reduziert, wodurch die thermische Regeneration und/oder das Langzeitverhalten des Erdreichs an Bedeutung gewinnt.},
  language  = {de}
}
@article{BlankeHagenkampDoeringetal.2021,
  author    = {Blanke, Tobias and Hagenkamp, Markus and D{\"o}ring, Bernd and G{\"o}ttsche, Joachim and Reger, Vitali and Kuhnhenne, Markus},
  title     = {Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates},
  series = {Geothermal Energy},
  volume    = {9},
  journal   = {Geothermal Energy},
  number    = {Article number: 19},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {2195-9706},
  doi       = {10.1186/s40517-021-00201-3},
  pages     = {23 Seiten},
  year      = {2021},
  abstract  = {Previous studies optimized the dimensions of coaxial heat exchangers using constant mass fow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar fow types. In contrast, in this study, fow conditions in the circular ring are kept constant (a set of fxed Reynolds numbers) during optimization. This approach ensures fxed fow conditions and prevents inappropriately high or low mass fow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic efort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass fow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellstr{\"o}m's borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefcients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy diference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy fux and hydraulic efort. The Reynolds number in the circular ring is instead of the mass fow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54\% of the outer pipe radius for laminar fow and 60\% for turbulent fow scenarios. Net-exergetic optimization shows a predominant infuence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth's thermal properties and the fow type. Conclusively, coaxial geothermal probes' design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics.},
  language  = {en}
}
@article{AlexopoulosHoffschmidt2017,
  author    = {Alexopoulos, Spiros and Hoffschmidt, Bernhard},
  title     = {Advances in solar tower technology},
  series = {Wiley interdisciplinary reviews : Energy and Environment : WIREs},
  volume    = {6},
  journal   = {Wiley interdisciplinary reviews : Energy and Environment : WIREs},
  number    = {1},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {2041-840X},
  doi       = {10.1002/wene.217},
  pages     = {1 -- 19},
  year      = {2017},
  language  = {en}
}
@article{Alexopoulos2012,
  author    = {Alexopoulos, Spiros},
  title     = {Biogas systems: basics, biogas multifunction, principle of fermentation and hybrid application with a solar tower for the treatment of waste animal manure},
  series = {Journal of Engineering Science and Technology Review},
  volume    = {5},
  journal   = {Journal of Engineering Science and Technology Review},
  number    = {4},
  issn      = {1791-2377},
  pages     = {48 -- 55},
  year      = {2012},
  abstract  = {Two of the main environmental problems of today's society are the continuously increasing production of organic wastes as well as the increase of carbon dioxide in the atmosphere and the related green house effect. A way to solve these problems is the production of biogas. Biogas is a combustible gas consisting of methane, carbon dioxide and small amounts of other gases and trace elements. Production of biogas through anaerobic digestion of animal manure and slurries as well as of a wide range of digestible organic wastes and agricultural residues, converts these substrates into electricity and heat and offers a natural fertiliser for agriculture. The microbiological process of decomposition of organic matter, in the absence of oxygen takes place in reactors, called digesters. Biogas can be used as a fuel in a gas turbine or burner and can be used in a hybrid solar tower system offering a solution for waste treatment of agricultural and animal residues. A solar tower system consists of a heliostat field, which concentrates direct solar irradiation on an open volumetric central receiver. The receiver heats up ambient air to temperatures of around 700°C. The hot air's heat energy is transferred to a steam Rankine cycle in a heat recovery steam generator (HRSG). The steam drives a steam turbine, which in turn drives a generator for producing electricity. In order to increase the operational hours of a solar tower power plant, a heat storage system and/ or hybridization may be considered. The advantage of solar-fossil hybrid power plants, compared to solar-only systems, lies in low additional investment costs due to an adaptable solar share and reduced technical and economical risks. On sunny days the hybrid system operates in a solar-only mode with the central receiver and on cloudy days and at night with the gas turbine only. As an alternative to methane gas, environmentally neutral biogas can be used for operating the gas turbine. Hence, the hybrid system is operated to 100\% from renewable energy sources},
  language  = {en}
}
@article{Alexopoulos2015,
  author    = {Alexopoulos, Spiros},
  title     = {Simulation model for the transient process behaviour of solar aluminium recycling in a rotary kiln},
  series = {Applied Thermal Engineering},
  volume    = {78},
  journal   = {Applied Thermal Engineering},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1359-4311},
  doi       = {10.1016/j.applthermaleng.2015.01.007},
  pages     = {387 -- 396},
  year      = {2015},
  language  = {en}
}
@article{AgrafiotisMavroidisKonstandopoulosetal.2007,
  author    = {Agrafiotis, Christos C. and Mavroidis, Ilias and Konstandopoulos, Athansios G. and Hoffschmidt, Bernhard and Stobbe, Per and Romero, Manuel and Fernandez-Quero, Valerio},
  title     = {Evaluation of porous silicon carbide monolithic honeycombs as volumetric receivers/collectors of concentrated solar radiation},
  series = {Solar energy materials and solar cells},
  volume    = {Vol. 91},
  journal   = {Solar energy materials and solar cells},
  number    = {Iss. 6},
  issn      = {1879-3398 (E-Journal); 0927-0248 (Print)},
  pages     = {474 -- 488},
  year      = {2007},
  language  = {en}
}