Characterization of a large lab-scale latent heat storage

Abstract

According to the 2nd law of thermodynamics, a driving temperature difference is always required for the transfer of heat resulting in a higher charging than discharging temperature of thermal energy storages. By using latent heat thermal energy storage (LH-TES), the driving temperature difference between charging and discharging can be minimized, resulting in higher exergetic efficiency. A dual-tube LH-TES concept was developed and tested with an organic Rankine cycle and a high temperature heat pump, as discussed at the ISEC in 2024. Thereafter, testing in an extended parameter range of temperatures and mass flow rates was conducted in order to allow for an in-depth characterization of the system. The results show that the LH-TES with a nominal melting temperature of 133 °C is capable of storing up to 124 kWh of heat in a temperature range of 104 to 139 °C with a maximum heat flow rate of up to 90 kW. Data from the experimental analysis will be shown and discussed.