Performance analysis on a hybrid compression-assisted sorption thermal battery for seasonal heat storage in severe cold region

Sorption thermal battery has revealed vast potential of heat utilization to address the issue of long-term energy storage. A hybrid compression-assisted sorption thermal battery is presented for solar energy utilization, which aims to solve the mismatch of heat storage and supply in cold region. Thermodynamic performance of the hybrid sorption thermal battery in cold region is analyzed by using MnCl2-SrCl2 and MnCl2-CaCl2 working pairs and then compared with that of basic sorption type with internal heat recovery. It is demonstrated that when ambient temperature in winter ranges from -30 degrees C to -5 degrees C, energy and exergy efficiencies of hybrid thermal battery using different working pairs increase from 0.74 to 0.865 and 0.25 to 0.43, respectively. Energy efficiency of hybrid thermal battery is almost twice higher than that of basic type with internal heat recovery. For different operating parameters, mass ratio and global conversion rate have a larger influence on thermal performance than isentropic efficiency of compressor. Although energy storage density per salt of basic sorption thermal battery is a bit higher than that of hybrid type, the density per reactor of hybrid compression-assisted thermal battery could be improved by 50%, which indicates a good system compactness in real application. (C) 2021 Elsevier Ltd. All rights reserved.