Performance of thermochemical adsorption heat storage system based on MnCl2-NH3 working pair

Abstract

As a leading technology of heat storage, thermochemical adsorption heat storage has become a hot research direction in the world because of its high heat storage density, which can realize cross season heat storage and combined cold and heat storage. In this study, a thermochemical adsorption heat storage system with MnCl2-NH3 as working pair is constructed. MnCl2@expanded graphite composite adsorbent has been prepared by adding expanded graphite (EG) to suppress the expansion and agglomeration of chemical salts, and 3.78 kg MnCl2@EG are filled in the chemical reactor. The heat storage performance of the MnCl2-NH3 thermochemical adsorption heat storage system is experimentally tested. The optimal heat storage performance was obtained when the charging, discharging and condensation/evaporation temperature is 174 °C, 50 °C and 20 °C, respectively. The corresponding total heat storage density is 3211.56 kJ/kg MnCl2 (or 2729.82 kJ/kg consolidated composite material) with the total heat storage efficiency 0.939. The experimental results revealed that MnCl2@EG composite exhibits the superior heat storage performance and could be a promising thermochemical adsorption heat storage material. The thermochemical adsorption heat storage could be used for harvesting the solar thermal energy in large scale and recovering the industrial waste heat.