@inproceedings{MahdiDerschSchmitzetal.2022,
  author    = {Mahdi, Zahra and Dersch, J{\"u}rgen and Schmitz, Pascal and Dieckmann, Simon and Chico Caminos, Ricardo Alexander and Teixeira Boura, Cristiano Jos{\´e} and Herrmann, Ulf and Schwager, Christian and Schmitz, Mark and Gielen, Hans and Gedle, Yibekal and B{\"u}scher, Rauno},
  title     = {Technical assessment of Brayton cycle heat pumps for the integration in hybrid PV-CSP 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       = {10.1063/5.0086269},
  pages     = {11 Seiten},
  year      = {2022},
  abstract  = {The hybridization of Concentrated Solar Power (CSP) and Photovoltaics (PV) systems is a promising approach to reduce costs of solar power plants, while increasing dispatchability and flexibility of power generation. High temperature heat pumps (HT HP) can be utilized to boost the salt temperature in the thermal energy storage (TES) of a Parabolic Trough Collector (PTC) system from 385 °C up to 565 °C. A PV field can supply the power for the HT HP, thus effectively storing the PV power as thermal energy. Besides cost-efficiently storing energy from the PV field, the power block efficiency of the overall system is improved due to the higher steam parameters. This paper presents a technical assessment of Brayton cycle heat pumps to be integrated in hybrid PV-CSP power plants. As a first step, a theoretical analysis was carried out to find the most suitable working fluid. The analysis included the fluids Air, Argon (Ar), Nitrogen (N2) and Carbon dioxide (CO2). N2 has been chosen as the optimal working fluid for the system. After the selection of the ideal working medium, different concepts for the arrangement of a HT HP in a PV-CSP hybrid power plant were developed and simulated in EBSILON®Professional. The concepts were evaluated technically by comparing the number of components required, pressure losses and coefficient of performance (COP).},
  language  = {en}
}
@inproceedings{ZahraPhaniSrujanChicoCaminosetal.2022,
  author    = {Zahra, Mahdi and Phani Srujan, Merige and Chico Caminos, Ricardo Alexander 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{GedleSchmitzGielenetal.2022,
  author    = {Gedle, Yibekal and Schmitz, Mark and Gielen, Hans and Schmitz, Pascal and Herrmann, Ulf and Teixeira Boura, Cristiano Jos{\´e} and Mahdi, Zahra and Chico Caminos, Ricardo Alexander and Dersch, J{\"u}rgen},
  title     = {Analysis of an integrated CSP-PV hybrid power plant},
  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       = {10.1063/5.0086236},
  pages     = {9 Seiten},
  year      = {2022},
  abstract  = {In the past, CSP and PV have been seen as competing technologies. Despite massive reductions in the electricity generation costs of CSP plants, PV power generation is - at least during sunshine hours - significantly cheaper. If electricity is required not only during the daytime, but around the clock, CSP with its inherent thermal energy storage gets an advantage in terms of LEC. There are a few examples of projects in which CSP plants and PV plants have been co-located, meaning that they feed into the same grid connection point and ideally optimize their operation strategy to yield an overall benefit. In the past eight years, TSK Flagsol has developed a plant concept, which merges both solar technologies into one highly Integrated CSP-PV-Hybrid (ICPH) power plant. Here, unlike in simply co-located concepts, as analyzed e.g. in [1] - [4], excess PV power that would have to be dumped is used in electric molten salt heaters to increase the storage temperature, improving storage and conversion efficiency. The authors demonstrate the electricity cost sensitivity to subsystem sizing for various market scenarios, and compare the resulting optimized ICPH plants with co-located hybrid plants. Independent of the three feed-in tariffs that have been assumed, the ICPH plant shows an electricity cost advantage of almost 20\% while maintaining a high degree of flexibility in power dispatch as it is characteristic for CSP power plants. As all components of such an innovative concept are well proven, the system is ready for commercial market implementation. A first project is already contracted and in early engineering execution.},
  language  = {en}
}
@inproceedings{NiederwestbergSchneiderTeixeiraBouraetal.2022,
  author    = {Niederwestberg, Stefan and Schneider, Falko and Teixeira Boura, Cristiano Jos{\´e} and Herrmann, Ulf},
  title     = {Introduction to a direct irradiated transparent tube particle receiver},
  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       = {10.1063/5.0086735},
  pages     = {9 Seiten},
  year      = {2022},
  abstract  = {New materials often lead to innovations and advantages in technical applications. This also applies to the particle receiver proposed in this work that deploys high-temperature and scratch resistant transparent ceramics. With this receiver design, particles are heated through direct-contact concentrated solar irradiance while flowing downwards through tubular transparent ceramics from top to bottom. In this paper, the developed particle receiver as well as advantages and disadvantages are described. Investigations on the particle heat-up characteristics from solar irradiance were carried out with DEM simulations which indicate that particle temperatures can reach up to 1200 K. Additionally, a simulation model was set up for investigating the dynamic behavior. A test receiver at laboratory scale has been designed and is currently being built. In upcoming tests, the receiver test rig will be used to validate the simulation results. The design and the measurement equipment is described in this work.},
  language  = {en}
}
@techreport{GhinaiyaLehmannGoettsche2022,
  author    = {Ghinaiya, Jagdishkumar and Lehmann, Thomas and G{\"o}ttsche, Joachim},
  title     = {LOCAL+ - ein kreislauff{\"a}higer Holzmodulbau mit nachhaltigem Energie- und Wohnraumkonzept},
  series = {Bauphysik},
  volume    = {44},
  journal   = {Bauphysik},
  number    = {3},
  publisher = {Ernst \& Sohn},
  address   = {Hoboken},
  issn      = {0171-5445 (Print)},
  doi       = {10.1002/bapi.202200010},
  pages     = {136 -- 142},
  year      = {2022},
  abstract  = {Mit dem Beitrag des Teams der FH Aachen zum SDE 21/22 wird im Projekt LOCAL+ ein kreislauff{\"a}higer Holzmodulbau mit einem innovativen Wohnraumkonzept geplant und umgesetzt. Ziel dieses Konzeptes ist die Verringerung des stetig steigenden Wohnfl{\"a}chenbedarfs durch ein Raum-in-Raum Konzept. Geb{\"a}udetechnisch wird in dem Projekt nicht nur das Einzelgeb{\"a}ude betrachtet, sondern unter Ber{\"u}cksichtigung des Geb{\"a}udebestandes wird f{\"u}r das Quartier ein innovatives und nachhaltiges Energiekonzept entwickelt. Ein zentrales Wasserstoffsystem ist f{\"u}r ein Quartier geplant, um den Stromverbrauch aus dem Netz im Winter zu reduzieren. Zentraler Bestandteil des TGA-Konzepts ist ein unterirdischer Eisspeicher, eine PVT und eine W{\"a}rmepumpe mit intelligenter Regelstrategie. Ein Teil des neuen Geb{\"a}udes (Design Challenge DC) wird in Wuppertal als Hausdemonstrationseinheit (HDU) pr{\"a}sentiert. Eine hygrothermische Simulation der HDU wurde mit der WUFI-Software durchgef{\"u}hrt. Da im Innenraum Lehmmodule und -platten als Feuchtigkeitspuffer verwendet werden, spielen die Themen Feuchtigkeit, Holzf{\"a}ule und Schimmelwachstum eine wichtige Rolle.},
  language  = {de}
}
@inproceedings{BlankeSchmidtGoettscheetal.2022,
  author    = {Blanke, Tobias and Schmidt, Katharina S. and G{\"o}ttsche, Joachim and D{\"o}ring, Bernd and Frisch, J{\´e}r{\^o}me and van Treeck, Christoph},
  title     = {Time series aggregation for energy system design: review and extension of modelling seasonal storages},
  series = {Energy Informatics},
  volume    = {5},
  booktitle = {Energy Informatics},
  number    = {1, Article number: 17},
  editor    = {Weidlich, Anke and Neumann, Dirk and Gust, Gunther and Staudt, Philipp and Sch{\"a}fer, Mirko},
  publisher = {Springer Nature},
  issn      = {2520-8942},
  doi       = {10.1186/s42162-022-00208-5},
  pages     = {14 Seiten},
  year      = {2022},
  abstract  = {Using optimization to design a renewable energy system has become a computationally demanding task as the high temporal fluctuations of demand and supply arise within the considered time series. The aggregation of typical operation periods has become a popular method to reduce effort. These operation periods are modelled independently and cannot interact in most cases. Consequently, seasonal storage is not reproducible. This inability can lead to a significant error, especially for energy systems with a high share of fluctuating renewable energy. The previous paper, "Time series aggregation for energy system design: Modeling seasonal storage", has developed a seasonal storage model to address this issue. Simultaneously, the paper "Optimal design of multi-energy systems with seasonal storage" has developed a different approach. This paper aims to review these models and extend the first model. The extension is a mathematical reformulation to decrease the number of variables and constraints. Furthermore, it aims to reduce the calculation time while achieving the same results.},
  language  = {en}
}
@article{PeereBlanke2022,
  author    = {Peere, Wouter and Blanke, Tobias},
  title     = {GHEtool: An open-source tool for borefield sizing in Python},
  series = {Journal of Open Source Software},
  volume    = {7},
  journal   = {Journal of Open Source Software},
  number    = {76},
  editor    = {Vernon, Chris},
  issn      = {2475-9066},
  doi       = {10.21105/joss.04406},
  pages     = {1 -- 4, 4406},
  year      = {2022},
  abstract  = {GHEtool is a Python package that contains all the functionalities needed to deal with borefield design. It is developed for both researchers and practitioners. The core of this package is the automated sizing of borefield under different conditions. The sizing of a borefield is typically slow due to the high complexity of the mathematical background. Because this tool has a lot of precalculated data, GHEtool can size a borefield in the order of tenths of milliseconds. This sizing typically takes the order of minutes. Therefore, this tool is suited for being implemented in typical workflows where iterations are required. GHEtool also comes with a graphical user interface (GUI). This GUI is prebuilt as an exe-file because this provides access to all the functionalities without coding. A setup to install the GUI at the user-defined place is also implemented and available at: https://www.mech.kuleuven.be/en/tme/research/thermal_systems/tools/ghetool.},
  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 2022 conference proceedings},
  booktitle = {SolarPACES 2022 conference proceedings},
  number    = {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{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 2022 conference proceedings},
  booktitle = {SolarPACES 2022 conference proceedings},
  number    = {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}
}
@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}
}