@inproceedings{ZahraPhaniSrujanCaminosetal.2022,
  author    = {Zahra, Mahdi and Phani Srujan, Merige and Caminos, Ricardo Alexander Chico and Schmitz, Pascal and Herrmann, Ulf and Teixeira Boura, Cristiano Jos{\´e} and Schmitz, Mark and Gielen, Hans and Gedle, Yibekal and Dersch, J{\"u}rgen},
  title     = {Modeling the thermal behavior of solar salt in electrical resistance heaters for the application in PV-CSP hybrid power plants},
  series = {SOLARPACES 2020},
  booktitle = {SOLARPACES 2020},
  number    = {2445 / 1},
  publisher = {AIP conference proceedings / American Institute of Physics},
  address   = {Melville, NY},
  isbn      = {978-0-7354-4195-8},
  issn      = {1551-7616 (online)},
  doi       = {10.1063/5.0086268},
  pages     = {9 Seiten},
  year      = {2022},
  abstract  = {Concentrated Solar Power (CSP) systems are able to store energy cost-effectively in their integrated thermal energy storage (TES). By intelligently combining Photovoltaics (PV) systems with CSP, a further cost reduction of solar power plants is expected, as well as an increase in dispatchability and flexibility of power generation. PV-powered Resistance Heaters (RH) can be deployed to raise the temperature of the molten salt hot storage from 385 °C up to 565 °C in a Parabolic Trough Collector (PTC) plant. To avoid freezing and decomposition of molten salt, the temperature distribution in the electrical resistance heater is investigated in the present study. For this purpose, a RH has been modeled and CFD simulations have been performed. The simulation results show that the hottest regions occur on the electric rod surface behind the last baffle. A technical optimization was performed by adjusting three parameters: Shell-baffle clearance, electric rod-baffle clearance and number of baffles. After the technical optimization was carried out, the temperature difference between the maximum temperature and the average outlet temperature of the salt is within the acceptable limits, thus critical salt decomposition has been avoided. Additionally, the CFD simulations results were analyzed and compared with results obtained with a one-dimensional model in Modelica.},
  language  = {en}
}
@inproceedings{TeixeiraBouraNiederwestbergMcLeodetal.2016,
  author    = {Teixeira Boura, Cristiano Jos{\´e} and Niederwestberg, Stefan and McLeod, Jacqueline and Herrmann, Ulf and Hoffschmidt, Bernhard},
  title     = {Development of heat exchanger for high temperature energy storage with bulk materials},
  series = {AIP Conference Proceedings},
  volume    = {1734},
  booktitle = {AIP Conference Proceedings},
  number    = {1},
  doi       = {10.1063/1.4949106},
  pages     = {050008-1 -- 050008-7},
  year      = {2016},
  language  = {en}
}
@inproceedings{TeixeiraBouraEcksteinFelinksetal.2011,
  author    = {Teixeira Boura, Cristiano Jos{\´e} and Eckstein, J. and Felinks, J. and G{\"o}ttsche, Joachim and Hoffschmidt, Bernhard and Schmitz, S.},
  title     = {3-D CFD simulation of an air-sand heat exchanger},
  series = {SolarPACES 2011 : concentrating solar power and chemical energy systems : 20 - 23 September, 2011, Granada, Spain},
  booktitle = {SolarPACES 2011 : concentrating solar power and chemical energy systems : 20 - 23 September, 2011, Granada, Spain},
  address   = {Granada},
  pages     = {1 CD-ROM},
  year      = {2011},
  language  = {en}
}
@inproceedings{SchwagerTeixeiraBouraFleschetal.2019,
  author    = {Schwager, Christian and Teixeira Boura, Cristiano Jos{\´e} and Flesch, Robert and Alexopoulos, Spiros and Herrmann, Ulf},
  title     = {Improved efficiency prediction of a molten salt receiver based on dynamic cloud passage simulation},
  series = {AIP Conference Proceedings},
  volume    = {2126},
  booktitle = {AIP Conference Proceedings},
  number    = {1},
  isbn      = {978-0-7354-1866-0},
  doi       = {10.1063/1.5117566},
  pages     = {030054-1 -- 030054-8},
  year      = {2019},
  language  = {en}
}
@article{SchwagerFleschSchwarzboezletal.2022,
  author    = {Schwager, Christian and Flesch, Robert and Schwarzb{\"o}zl, Peter and Herrmann, Ulf and Teixeira Boura, Cristiano Jos{\´e}},
  title     = {Advanced two phase flow model for transient molten salt receiver system simulation},
  series = {Solar Energy},
  volume    = {232},
  journal   = {Solar Energy},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0038-092X (print)},
  doi       = {10.1016/j.solener.2021.12.065},
  pages     = {362 -- 375},
  year      = {2022},
  abstract  = {In order to realistically predict and optimize the actual performance of a concentrating solar power (CSP) plant sophisticated simulation models and methods are required. This paper presents a detailed dynamic simulation model for a Molten Salt Solar Tower (MST) system, which is capable of simulating transient operation including detailed startup and shutdown procedures including drainage and refill. For appropriate representation of the transient behavior of the receiver as well as replication of local bulk and surface temperatures a discretized receiver model based on a novel homogeneous two-phase (2P) flow modelling approach is implemented in Modelica Dymola®. This allows for reasonable representation of the very different hydraulic and thermal properties of molten salt versus air as well as the transition between both. This dynamic 2P receiver model is embedded in a comprehensive one-dimensional model of a commercial scale MST system and coupled with a transient receiver flux density distribution from raytracing based heliostat field simulation. This enables for detailed process prediction with reasonable computational effort, while providing data such as local salt film and wall temperatures, realistic control behavior as well as net performance of the overall system. Besides a model description, this paper presents some results of a validation as well as the simulation of a complete startup procedure. Finally, a study on numerical simulation performance and grid dependencies is presented and discussed.},
  language  = {en}
}
@inproceedings{SchwagerAngeleSchwarzboezletal.2023,
  author    = {Schwager, Christian and Angele, Florian and Schwarzb{\"o}zl, Peter and Teixeira Boura, Cristiano Jos{\´e} and Herrmann, Ulf},
  title     = {Model predictive assistance for operational decision making in molten salt receiver systems},
  series = {SolarPACES: Solar Power \& Chemical Energy Systems},
  booktitle = {SolarPACES: Solar Power \& Chemical Energy Systems},
  number    = {2815 / 1},
  publisher = {AIP conference proceedings / American Institute of Physics},
  address   = {Melville, NY},
  isbn      = {978-0-7354-4623-6},
  issn      = {1551-7616 (online)},
  doi       = {10.1063/5.0151514},
  pages     = {8 Seiten},
  year      = {2023},
  abstract  = {Despite the challenges of pioneering molten salt towers (MST), it remains the leading technology in central receiver power plants today, thanks to cost effective storage integration and high cost reduction potential. The limited controllability in volatile solar conditions can cause significant losses, which are difficult to estimate without comprehensive modeling [1]. This paper presents a Methodology to generate predictions of the dynamic behavior of the receiver system as part of an operating assistance system (OAS). Based on this, it delivers proposals if and when to drain and refill the receiver during a cloudy period in order maximize the net yield and quantifies the amount of net electricity gained by this. After prior analysis with a detailed dynamic two-phase model of the entire receiver system, two different reduced modeling approaches where developed and implemented in the OAS. A tailored decision algorithm utilizes both models to deliver the desired predictions efficiently and with appropriate accuracy.},
  language  = {en}
}
@inproceedings{SchwagerAngeleNourietal.2022,
  author    = {Schwager, Christian and Angele, Florian and Nouri, Bijan and Schwarzb{\"o}zl, Peter and Teixeira Boura, Cristiano Jos{\´e} and Herrmann, Ulf},
  title     = {Impact of DNI forecast quality on performance prediction for a commercial scale solar tower: Application of nowcasting DNI maps to dynamic solar tower simulation},
  series = {SolarPACES conference proceedings},
  booktitle = {SolarPACES conference proceedings},
  number    = {Vol. 1},
  publisher = {TIB Open Publishing},
  address   = {Hannover},
  issn      = {2751-9899 (online)},
  doi       = {10.52825/solarpaces.v1i.675},
  pages     = {9 Seiten},
  year      = {2022},
  abstract  = {Concerning current efforts to improve operational efficiency and to lower overall costs of concentrating solar power (CSP) plants with prediction-based algorithms, this study investigates the quality and uncertainty of nowcasting data regarding the implications for process predictions. DNI (direct normal irradiation) maps from an all-sky imager-based nowcasting system are applied to a dynamic prediction model coupled with ray tracing. The results underline the need for high-resolution DNI maps in order to predict net yield and receiver outlet temperature realistically. Furthermore, based on a statistical uncertainty analysis, a correlation is developed, which allows for predicting the uncertainty of the net power prediction based on the corresponding DNI forecast uncertainty. However, the study reveals significant prediction errors and the demand for further improvement in the accuracy at which local shadings are forecasted.},
  language  = {en}
}
@inproceedings{SchulteSchwagerNoureldinetal.2023,
  author    = {Schulte, Jonas and Schwager, Christian and Noureldin, Kareem and May, Martin and Teixeira Boura, Cristiano Jos{\´e} and Herrmann, Ulf},
  title     = {Gradient controlled startup procedure of a molten-salt power-to-heat energy storage plant based on dynamic process simulation},
  series = {SolarPACES: Solar Power \& Chemical Energy Systems},
  booktitle = {SolarPACES: Solar Power \& Chemical Energy Systems},
  number    = {2815 / 1},
  publisher = {AIP conference proceedings / American Institute of Physics},
  address   = {Melville, NY},
  isbn      = {978-0-7354-4623-6},
  issn      = {1551-7616 (online)},
  doi       = {10.1063/5.0148741},
  pages     = {9 Seiten},
  year      = {2023},
  abstract  = {The integration of high temperature thermal energy storages into existing conventional power plants can help to reduce the CO2 emissions of those plants and lead to lower capital expenditures for building energy storage systems, due to the use of synergy effects [1]. One possibility to implement that, is a molten salt storage system with a powerful power-to-heat unit. This paper presents two possible control concepts for the startup of the charging system of such a facility. The procedures are implemented in a detailed dynamic process model. The performance and safety regarding the film temperatures at heat transmitting surfaces are investigated in the process simulations. To improve the accuracy in predicting the film temperatures, CFD simulations of the electrical heater are carried out and the results are merged with the dynamic model. The results show that both investigated control concepts are safe regarding the temperature limits. The gradient controlled startup performed better than the temperature-controlled startup. Nevertheless, there are several uncertainties that need to be investigated further.},
  language  = {en}
}
@inproceedings{SchulteSchwagerFrantzetal.2022,
  author    = {Schulte, Jonas and Schwager, Christian and Frantz, Cathy and Schloms, Felix and Teixeira Boura, Cristiano Jos{\´e} and Herrmann, Ulf},
  title     = {Control concept for a molten salt receiver in star design: Development, optimization and testing with cloud passage scenarios},
  series = {SolarPACES conference proceedings},
  booktitle = {SolarPACES conference proceedings},
  number    = {Vol. 1},
  publisher = {TIB Open Publishing},
  address   = {Hannover},
  issn      = {2751-9899 (online)},
  doi       = {10.52825/solarpaces.v1i.693},
  pages     = {9 Seiten},
  year      = {2022},
  abstract  = {A promising approach to reduce the system costs of molten salt solar receivers is to enable the irradiation of the absorber tubes on both sides. The star design is an innovative receiver design, pursuing this approach. The unconventional design leads to new challenges in controlling the system. This paper presents a control concept for a molten salt receiver system in star design. The control parameters are optimized in a defined test cycle by minimizing a cost function. The control concept is tested in realistic cloud passage scenarios based on real weather data. During these tests, the control system showed no sign of unstable behavior, but to perform sufficiently in every scenario further research and development like integrating Model Predictive Controls (MPCs) need to be done. The presented concept is a starting point to do so.},
  language  = {en}
}
@inproceedings{SattlerCaminosUerlingsetal.2020,
  author    = {Sattler, Johannes, Christoph and Caminos, Ricardo Alexander Chico and {\"U}rlings, Nicolas and Dutta, Siddharth and Ruiz, Victor and Kalogirou, Soteris and Ktistis, Panayiotis and Agathokleous, Rafaela and Jung, Christian and Alexopoulos, Spiros and Atti, Vikrama Nagababu and Teixeira Boura, Cristiano Jos{\´e} and Herrmann, Ulf},
  title     = {Operational experience and behaviour of a parabolic trough collector system with concrete thermal energy storage for process steam generation in Cyprus},
  series = {AIP Conference Proceedings},
  booktitle = {AIP Conference Proceedings},
  number    = {2303},
  doi       = {10.1063/5.0029278},
  pages     = {140004-1 -- 140004-10},
  year      = {2020},
  language  = {en}
}