Long-Term Durability and Reactivation of Thermochemical Heat Storage Driven by the CaO/Ca(OH)<sub>2</sub> Reversible Reaction

Abstract

Thermochemical heat storage is a promising technology for improving thermal energy efficiency. To investigate the durability of the CaO/Ca(OH) 2 reaction and develop a reactivation method, repetitive charging/discharging operation of a packed bed reactor with a thick packed bed was conducted, and variations in the discharging behavior, final conversion, and reactant activity were investigated. Owing to the formation of a deactivated sintered reactant block, the discharging time halved and the final conversion ratio decreased by the 53rd discharging operation. To enhance durability, a reactivation method using high-pressure vapor was implemented during the 54th discharging operation. Following reactivation, the final conversion increased 15%, and the discharging time tripled when compared with the discharging operation before reactivation, confirming the success of this simple reactivation method.

Investigation on Long Term Operation of Thermochemical Heat Storage with MgO-Based Composite Honeycombs

“…A number of studies using CaO/Ca(OH) 2 have been conducted for systems with a temperature range of 500-600 • C, and tests were mainly conducted based on a stationary system. In addition to the basic research to observe the one cycle [9] or 20 cyclic stability of materials [10] or 59 cycles [11] in small fixed bed reactor, there has also been research to establish a thermal storage device for cyclic experiments. German Aerospace Center (DLR) constructed a thermal storage system using 2.4 kg [12] and 25 kg [13] of CaO and conducted a study to ascertain the stability of the system along with changes in material and performance through the operation of 35 cycles and more than 10 cycles, respectively.…”