Thermophysical characterization and thermal cycling stability of two TCM: CaCl2 and zeolite

Abstract

At this moment, the global energy consumption in buildings is around 40% of the total energy consumption in developed countries. Thermal energy storage (TES) is presented as one way to address this energyrelated problem proposing an alternative to reduce the gap between energy supply and energy demand. One way to store energy is using thermochemical materials (TCM). These types of materials allow accumulating energy through a chemical process at low temperature, almost without heat losses. In addition, it is a stable way to perform the heat storage and TCM can be implemented for seasonal storage or/and long term storage. This study compares the cyclability, from the thermophysical point of view, CaCl2 which follows a chemical reaction and zeolite which follows a sorption process to be used as TCM for seasonal/long term storage. The main results show that the chemical reaction TCM is more energy-efficient than the sorption TCM. The CaCl2 calculated energy density is 1.47 GJ/m3 , being the best option to be considered to be used as TCM, even though the dehydration process of the zeolite is simpler and it occurs at higher temperatures its calculated energy density is only 0.2 GJ/m3 .

The research leading to these results has received funding from the European Commission Seventh Framework Programme (FP/ 2007-2013) under grant agreement No ENER/FP7/1295983 (MERITS) and under grant agreement no. PIRSES-GA-2013-610692 (INNOSTORAGE). Furthermore, the work is partially funded by the Spanish government (ENE2011-28269-C03-02 and ENE2011- 22722), and the European Union by Cost Action TU0802. The authors would like to thank the Catalan Government for the quality accreditation given to their research groups GREA (2014 SGR 123) and DIOPMA (2014 SGR 1543).