Experimental and numerical investigation of a 4 MWh high temperature molten salt thermocline storage system with filler

In this work a brief introduction into the thermocline molten salt energy storage concept is given. This concept allows storing hot and cold molten salt inside a single tank. By adding a filler material to the storage tank, a large fraction of molten salt can be substituted, thus reducing total cost significantly. For the investigation of the thermocline concept with filler, DLR's test facility for thermal energy storage in molten salts (TESIS) has been equipped with basalt filler material. A total of 166 thermocouples were embedded inside the packed bed to measure the temperature field. This publication presents experimental results of a charging and discharging cycle at 2 kg/s mass flow rate and temperatures between 290°C and 560°C. The inlet temperatures are fed into a numerical model, which showed good agreement with measured temperatures inside the storage volume, if some bypasses of the bulk flow are considered. Some inconsistencies were identified which need to be addressed in the future.