Design and performance evaluation of an innovative salt hydrates-based reactor for thermochemical energy storage

Abstract

Thermochemical energy storage (TCES) with salt hydrates has attracted much attention due to its high energy storage density, low regeneration temperature, and long-term storage without energy loss. As a key component of the TCES system, the reactor has a major influence on the system performance. The traditional reactor has problems of non-uniform reaction and easy liquefaction of salt hydrates. To address the above issues, in present paper, it designed a novel reactor which could disperse the air flow to increase the contact area between the air and the salt hydrates for more uniform reaction. The air outlet channel extended into the salt bed, facilitating fast removal of water vapor generated by dehydration, which could reduce the possibility of salt liquefaction. Compared with the existing reactor, the novel reactor reduced the reaction time by 26 % and increased the thermal efficiency by around 2.5 % under the same conditions. Then the inlet air temperature, inlet air flow rate, material porosity and parameters of reactor geometry were investigated to optimize the performance of the reactor. It was found both the thermal efficiency and reaction time were most sensitive to the inlet air temperature. When the inlet air temperature increased from 353 K to 365 K, the reaction process was shortened by 35.36 % and the charging efficiency increased by 15 %. In addition, it was found there was an optimal length of the outflow channel (ha = 0.17 m) with which the reaction time was the shortest and the thermal efficiency was the highest.