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Energy storage systems are essential to reduce CO2 emissions caused by energy generation for a number of reasons. On the one hand, the volatile nature of renewable energies requires storage capacities in order to guarantee a reliable supply at all times, and on the other hand, energy storage systems allow the load to be smoothed out, enabling existing power plants to be operated more efficiently and the share of climate-friendly energy generation to be increased. In addition to electrical storage systems, thermal storage systems used in district heating systems are also very important. Improving the design and usage of new and existing district heating networks requires precise models for thermal storage systems of any size and any application. Validating these models using real world data is crucial. So far, most researchers have focused on smaller short-term storage systems or larger seasonal storage systems, but not on larger short-term storage systems.

For this reason, we will carry out high-resolution temperature measurements on the short-term thermal storage system of Entega AG, which is currently under construction. The obtained data enables the creation and validation of a detailed three-dimensional CFD model. This allows us to study the thermodynamic processes during loading and unloading, as well as during standby operation, which are important to understand and predict the system’s performance. Since the computational complexity of this model is very high, it is not suitable for a simulation of the entire district heating network and its interaction with the thermal storage system, as the timeframe of such a simulation is in the months and years. We will therefore derive and validate simplified one-dimensional models.