Westphal, JanJanWestphalBrunnemann, JohannesJohannesBrunnemannSpeerforck, ArneArneSpeerforck2025-03-312025-03-312025-05-01Energy 322: 135434 (2025)https://hdl.handle.net/11420/55016District heating networks (DHN) are an essential part of the decarbonization of the heating sector. As a high proportion of the buildings provided with district heating are integrated into larger networks, there is a need for efficient simulation tools that enable the simulation of large-scale DHN. This paper introduces a modeling concept for the dynamic simulation of DHN with several thousand substations using the modeling language Modelica. The emphasis is on the simulation of strongly meshed networks, usually appearing in large-scale DHN. To test the modeling concept, a generic, large-scale DHN is designed and simulated. The results are used to determine the time constants of the DHN for different load cases and evaluate the efficiency of the heat provision. We show that our modeling concept is suitable to simulate a DHN with 2167 substations, while the results suggest that there is still room for upscaling. To make the modeling concept fully open-source, a smaller DHN model is designed and simulated in OpenModelica. A comparison to Dymola shows that Dymola is not only 15 times faster in terms of simulation time; it also needs much less time for the translation and compilation of the model, highlighting future development of OpenModelica.en0360-54422025https://creativecommons.org/licenses/by/4.0/District heating network | Dynamic simulation | Large-scale | ModelicaTechnology::620: Engineering::620.1: Engineering Mechanics and Materials ScienceComputer Science, Information and General Works::004: Computer SciencesJournal Articlehttps://doi.org/10.15480/882.1497510.1016/j.energy.2025.13543410.15480/882.14975Journal Article