A new strategy of dual-material reactors for stable thermal output of sorption thermal battery

Sorption thermal battery driven by air humidity is a promising alternative technology to traditional methods of burning fossil fuels for space heating. Its dominant design of one-material reactor faces technical bottlenecks of unstable discharging thermal output and low energy efficiency. Herein, a new strategy of cascaded dual-material reactors was proposed as a solution, by utilizing their different sorption characterizations at material level and “reaction wave” properties at system level. A proof-of-concept prototype was established, whose main and regulatory reactor were packed with AA-15% LiCl composite and SrBr2·H2O, respectively. Experimental results demonstrated that the regulatory reactor has a strong stabilization function of the unstable output temperature of the main reactor, with the average output temperature fluctuations under 1.5 °C. The discharging/charging energy efficiency was increased by 0.4–1.7 times compared with one-material reactor. The output temperature level and heating power can be simply adjusted by changing the inlet air humidity and air velocity. Moreover, the influences of the lengths of two reactors on the thermal output and system operations were evaluated. Possible strategies to further enhance the multistage utilization of the charging energy were proposed. This new design strategy can contribute to the popularization and application of sorption thermal battery.