Thermal modelling of the discharge of a 180 kW·h latent thermal energy storage demonstrator

This paper presents the validation of a numerical model against experimental data for the discharge of a latent thermal energy storage. The experimental data come from the experimental characterization of 180 kW·h phase change material storage demonstrator installed in a substation of the Grenoble district heating network. The heat transfer fluid used is water and the phase change material is RT70HC. The numerical model has been presented and validated for different charging cases in a previous paper. This paper focus on the modelling of the phase-change during discharges, as the RT70HC has two solidification peaks. The model is a 1.5D model, developed in the DYMOLA software, with a 1D homogeneous approach for the heat transfer fluid combined with a 1.5D approach for the phase change material. The model with two solidification peaks reproduces the total energy unloaded during a discharge with an accuracy of 98.3 %, a root-mean-square error of 3 kW on outlet power and 1.6 °C for storage outlet temperature. These results are slightly better than a model with one peak of solidification (accuracy of 98 %, root-mean-square error of 3.22 kW on outlet power and 1.7 °C for storage outlet temperature). The conclusion is that consideration of the two peaks in this case is not mandatory. • Developing a 1.5D model for shell-and-tubes Latent Heat Thermal Energy Storages • Validation of the model against experimental data (180kWh storage demonstrator) • Validation on discharge experimental data (PCM solidification) • Particular PCM (RT70HC) with two plateaus of solidification • Minor impact of the PCM solidification model on the macroscopic results