Experimental analysis of a high-performance open sorption thermal storage system with absorption-crystallization-adsorption processes

Abstract

Sorption thermal energy storage is one of the promising solar thermal energy storage considering its long-term storage ability. Since the common sorption thermal storage suffers from low sorption capacity, a high energy storage density enhancement mechanism is always essential for a cost-effective and compact storage system. With three-phase sorption thermal storage, high energy storage density from the crystallization sorption process can be achieved. However, such a sorption process brings significant challenges, including crystal blockage issues in absorption system or solution leakage handling problems in adsorption system, which need to be resolved. Here, we showed a high-performance sorption thermal storage that can attain high energy storage density via a full liquid-to-solid state sorption process. Such a process is achieved by adopting moist air as heat and mass transfer media, which enables liquid absorption, crystallization, and solid adsorption in a simple configuration simultaneously. The lab-scale model achieved high energy storage density in the range of 333–405 kWh/m3 resulting from the heat of absorption and crystallization of LiCl, which is the record value for liquid absorption systems. The energy storage density obtained from the dual liquid and solid sorption processes is enhanced by 278 % compared with that of the conventional cycle at 70 % RH (relative humidity) and temperature lift of 10 °C. With simple construction and high energy storage density, the proposed system has great potential in real applications.