@article{PuppeGiulianoFrantzetal.2018,
  author    = {Puppe, Michael and Giuliano, Stefano and Frantz, Cathy and Uhlig, Ralf and Schumacher, Ralph and Ibraheem, Wagdi and Schmalz, Stefan and Waldmann, Barbara and Guder, Christoph and Peter, Dennis and Schwager, Christian and Teixeira Boura, Cristiano Jos{\´e} and Alexopoulos, Spiros and Spiegel, Michael and Wortmann, J{\"u}rgen and Hinrichs, Matthias and Engelhard, Manfred and Aust, Michael},
  title     = {Techno-economic optimization of molten salt solar tower plants},
  series = {AIP Conference Proceedings art.no. 040033},
  volume    = {2033},
  journal   = {AIP Conference Proceedings art.no. 040033},
  number    = {Issue 1},
  publisher = {AIP Publishing},
  address   = {Melville, NY},
  doi       = {10.1063/1.5067069},
  year      = {2018},
  abstract  = {In this paper the results of a techno-economic analysis of improved and optimized molten salt solar tower plants (MSSTP plants) are presented. The potential improvements that were analyzed include different receiver designs, different designs of the HTF-system and plant control, increased molten salt temperatures (up to 640°C) and multi-tower systems. Detailed technological and economic models of the solar field, solar receiver and high temperature fluid system (HTF-system) were developed and used to find potential improvements compared to a reference plant based on Solar Two technology and up-to-date cost estimations. The annual yield model calculates the annual outputs and the LCOE of all variants. An improved external tubular receiver and improved HTF-system achieves a significant decrease of LCOE compared to the reference. This is caused by lower receiver cost as well as improvements of the HTF-system and plant operation strategy, significantly reducing the plant own consumption. A novel star receiver shows potential for further cost decrease. The cavity receiver concepts result in higher LCOE due to their high investment cost, despite achieving higher efficiencies. Increased molten salt temperatures seem possible with an adapted, closed loop HTF-system and achieve comparable results to the original improved system (with 565°C) under the given boundary conditions. In this analysis all multi tower systems show lower economic viability compared to single tower systems, caused by high additional cost for piping connections and higher cost of the receivers. REFERENCES},
  language  = {en}
}
@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{KearneyHerrmannNavaetal.2003,
  author    = {Kearney, D. and Herrmann, Ulf and Nava, P. and Kelly, B. and Mahoney, R. and Pacheco, J. and Cable, R. and Potrovitza, N. and Blake, D. and Price, H.},
  title     = {Assessment of a Molten Salt Heat Transfer Fluid in a Parabolic Trough Solar Field},
  series = {Journal of Solar Energy Engineering},
  volume    = {125},
  journal   = {Journal of Solar Energy Engineering},
  number    = {2},
  issn      = {1528-8986},
  doi       = {10.1115/1.1565087},
  pages     = {170 -- 176},
  year      = {2003},
  language  = {en}
}
@article{HerrmannSchwarzenbartDittmannGabriel2019,
  author    = {Herrmann, Ulf and Schwarzenbart, Marc and Dittmann-Gabriel, S{\"o}ren},
  title     = {Speicher statt Kohle. Integration thermischer Stromspeicher in vorhandene Kraftwerksstandorte},
  series = {BWK : Das Energie-Fachmagazin},
  volume    = {71},
  journal   = {BWK : Das Energie-Fachmagazin},
  number    = {4},
  publisher = {Springer-VDI-Verl.},
  address   = {D{\"u}sseldorf},
  issn      = {1436-4883},
  pages     = {42 -- 45},
  year      = {2019},
  language  = {de}
}
@article{WoliszSchuetzBlankeetal.2017,
  author    = {Wolisz, Henryk and Sch{\"u}tz, Thomas and Blanke, Tobias and Hagenkamp, Markus and Kohrn, Markus and Wesseling, Mark and M{\"u}ller, Dirk},
  title     = {Cost optimal sizing of smart buildings' energy system components considering changing end-consumer electricity markets},
  series = {Energy},
  volume    = {137},
  journal   = {Energy},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {10.1016/j.energy.2017.06.025},
  pages     = {715 -- 728},
  year      = {2017},
  language  = {en}
}
@article{RegerKuhnhenneEbbertetal.2020,
  author    = {Reger, Vitali and Kuhnhenne, Markus and Ebbert, Thiemo and Hachul, Helmut and Blanke, Tobias and D{\"o}ring, Bernd},
  title     = {Nutzung erneuerbarer Energien durch thermische Aktivierung von Komponenten aus Stahl},
  series = {Stahlbau},
  volume    = {2020},
  journal   = {Stahlbau},
  number    = {Volume 89, Issue 6512-519},
  publisher = {Ernst \& Sohn},
  address   = {Berlin},
  issn      = {1437-1049},
  doi       = {10.1002/stab.202000031},
  pages     = {512 -- 519},
  year      = {2020},
  abstract  = {Die Versorgung von Neubauten soll m{\"o}glichst weitgehend unabh{\"a}ngig von fossilen Energietr{\"a}gern erfolgen. Erneuerbare Energien spielen daf{\"u}r eine gewichtige Rolle. Eine gute M{\"o}glichkeit, erneuerbare Energien ohne viel zus{\"a}tzlichen Aufwand nutzbar zu machen, ist, bereits vorhandenen Komponenten im Geb{\"a}ude zus{\"a}tzliche Funktionen zu geben. Hier kann bspw. die Fassade oder das Dach solarthermisch aktiviert oder durch Fotovoltaikmodule erg{\"a}nzt werden. Auch Tiefgr{\"u}ndungen k{\"o}nnen neben der statischen Funktion noch eine geothermische Funktion zur Aufnahme oder Abgabe von W{\"a}rme erhalten. Neben der Erzeugung bietet sich auch f{\"u}r die Verteilung der W{\"a}rme oder K{\"a}lte im Geb{\"a}ude die Integration in Bauteile an. Hier kann bspw. der Boden durch eine Fußbodenheizung oder die Decke durch Deckenstrahlplatten aktiviert werden. Im Rahmen der Ver{\"o}ffentlichung wird auf die thermische Aktivierung von Stahlkomponenten eingegangen. Es wird eine L{\"o}sung vorgestellt, die vorgeh{\"a}ngte hinterl{\"u}ftete Stahlfassade (VHF) solarthermisch zu aktivieren. Außerdem werden zwei M{\"o}glichkeiten zur geothermischen Aktivierung von Tiefgr{\"u}ndungen mittels Stahlpf{\"a}hlen gezeigt. Zuletzt wird ein System zur thermischen Aktivierung von Stahltrapezprofilen an der Decke erl{\"a}utert, welches W{\"a}rme zuf{\"u}hren oder bei Bedarf abf{\"u}hren kann.},
  language  = {de}
}
@article{HagenkampBlankeDoering2021,
  author    = {Hagenkamp, Markus and Blanke, Tobias and D{\"o}ring, Bernd},
  title     = {Thermoelectric building temperature control: a potential assessment},
  series = {International Journal of Energy and Environmental Engineering},
  volume    = {13},
  journal   = {International Journal of Energy and Environmental Engineering},
  publisher = {Springer},
  address   = {Berlin},
  doi       = {10.1007/s40095-021-00424-x},
  pages     = {241 -- 254},
  year      = {2021},
  abstract  = {This study focuses on thermoelectric elements (TEE) as an alternative for room temperature control. TEE are semi-conductor devices that can provide heating and cooling via a heat pump effect without direct noise emissions and no refrigerant use. An efficiency evaluation of the optimal operating mode is carried out for different numbers of TEE, ambient temperatures, and heating loads. The influence of an additional heat recovery unit on system efficiency and an unevenly distributed heating demand are examined. The results show that TEE can provide heat at a coefficient of performance (COP) greater than one especially for small heating demands and high ambient temperatures. The efficiency increases with the number of elements in the system and is subject to economies of scale. The best COP exceeds six at optimal operating conditions. An additional heat recovery unit proves beneficial for low ambient temperatures and systems with few TEE. It makes COPs above one possible at ambient temperatures below 0 ∘C. The effect increases efficiency by maximal 0.81 (from 1.90 to 2.71) at ambient temperature 5 K below room temperature and heating demand Q˙h=100W but is subject to diseconomies of scale. Thermoelectric technology is a valuable option for electricity-based heat supply and can provide cooling and ventilation functions. A careful system design as well as an additional heat recovery unit significantly benefits the performance. This makes TEE superior to direct current heating systems and competitive to heat pumps for small scale applications with focus on avoiding noise and harmful refrigerants.},
  language  = {en}
}
@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{RegerKuhnhenneHachuletal.2019,
  author    = {Reger, Vitali and Kuhnhenne, Markus and Hachul, Helmut and D{\"o}ring, Bernd and Blanke, Tobias and G{\"o}ttsche, Joachim},
  title     = {Plusenergiegeb{\"a}ude 2.0 in Stahlleichtbauweise},
  series = {Stahlbau},
  volume    = {88},
  journal   = {Stahlbau},
  number    = {6},
  publisher = {Ernst \& Sohn},
  address   = {Berlin},
  issn      = {1437-1049 (E-journal), 0038-9145 (print)},
  doi       = {10.1002/stab.201900034},
  pages     = {522 -- 528},
  year      = {2019},
  language  = {de}
}
@article{SattlerRoegerSchwarzboezletal.2020,
  author    = {Sattler, Johannes, Christoph and R{\"o}ger, Marc and Schwarzb{\"o}zl, Peter and Buck, Reiner and Macke, Ansgar and Raeder, Christian and G{\"o}ttsche, Joachim},
  title     = {Review of heliostat calibration and tracking control methods},
  series = {Solar Energy},
  volume    = {207},
  journal   = {Solar Energy},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {10.1016/j.solener.2020.06.030},
  pages     = {110 -- 132},
  year      = {2020},
  abstract  = {Large scale central receiver systems typically deploy between thousands to more than a hundred thousand heliostats. During solar operation, each heliostat is aligned individually in such a way that the overall surface normal bisects the angle between the sun's position and the aim point coordinate on the receiver. Due to various tracking error sources, achieving accurate alignment ≤1 mrad for all the heliostats with respect to the aim points on the receiver without a calibration system can be regarded as unrealistic. Therefore, a calibration system is necessary not only to improve the aiming accuracy for achieving desired flux distributions but also to reduce or eliminate spillage. An overview of current larger-scale central receiver systems (CRS), tracking error sources and the basic requirements of an ideal calibration system is presented. Leading up to the main topic, a description of general and specific terms on the topics heliostat calibration and tracking control clarifies the terminology used in this work. Various figures illustrate the signal flows along various typical components as well as the corresponding monitoring or measuring devices that indicate or measure along the signal (or effect) chain. The numerous calibration systems are described in detail and classified in groups. Two tables allow the juxtaposition of the calibration methods for a better comparison. In an assessment, the advantages and disadvantages of individual calibration methods are presented.},
  language  = {en}
}