Solar thermal energy storage for heating and cooling application is a priority in the renewable energy future. Several research groups aim to create compact thermal energy storages with different approaches. Therefore, materials with higher volumetric energy density like phase change materials (PCM) and thermo-chemical materials (TCM) are investigated. In a TCM based thermal storage system, the thermal energy is used to separate the working pair in its educts and in the reversed process, thermal energy is released.

In the EU project COMTES, three research groups with different technological approaches aim to reduce the required storage volume assigned for seasonal thermal storage. In our group, the absorption-desorption energy storage concept with aqueous sodium hydroxide (NaOH-H2O) and water is used. By including solar collectors to provide energy for the charging process in summer, a sustainable storage system can be obtained.

The presented work focuses on the development of heat and mass exchangers from a sodium lye based TCM storage system. The key components for charging and discharging are the absorption-desorption unit and the required evaporation-condensation unit. In this paper, the development process, the set-up and measurement results are shown and an outlook for further work is given.