@inproceedings{LahrsKrisamHerrmann2023,
  author    = {Lahrs, Lennart and Krisam, Pierre and Herrmann, Ulf},
  title     = {Envisioning a collaborative energy system planning platform for the energy transition at the district level},
  series = {ECOS 2023. The 36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems},
  booktitle = {ECOS 2023. The 36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems},
  publisher = {Procedings of ECOS 2023},
  doi       = {10.52202/069564-0284},
  pages     = {3163 -- 3170},
  year      = {2023},
  abstract  = {Residential and commercial buildings account for more than one-third of global energy-related greenhouse gas emissions. Integrated multi-energy systems at the district level are a promising way to reduce greenhouse gas emissions by exploiting economies of scale and synergies between energy sources. Planning district energy systems comes with many challenges in an ever-changing environment. Computational modelling established itself as the state-of-the-art method for district energy system planning. Unfortunately, it is still cumbersome to combine standalone models to generate insights that surpass their original purpose. Ideally, planning processes could be solved by using modular tools that easily incorporate the variety of competing and complementing computational models. Our contribution is a vision for a collaborative development and application platform for multi-energy system planning tools at the district level. We present challenges of district energy system planning identified in the literature and evaluate whether this platform can help to overcome these challenges. Further, we propose a toolkit that represents the core technical elements of the platform. Lastly, we discuss community management and its relevance for the success of projects with collaboration and knowledge sharing at their core.},
  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{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}
}