Solid sorption thermal battery assisted by continuous compression process for efficient heat supply

Abstract

Ammonia-based sorption thermal battery (STB) is gathering momentum due to the advantage of high energy storage density and strong operation flexibility. To further improve the system adaptability to cold region, compression-assisted sorption thermal battery (CSTB) is inclined to reach a required heat release temperature by adjusting internal reaction pressure difference. However, the role of compression process in CSTB and its performance limiting factors under dynamic operating conditions remains unclear. This paper investigates the performance of CSTB by matching continuous compression processes under different working conditions. The results indicate that an average heat output power per kg MnCl2 adsorbent ranges from 0.042 kW to 0.26 kW when ambient temperature increases from −10 °C to −10 °C. Heat storage efficiency in an hour varies from 8% to 60%, and energy storage density (ESD) varies from 150 kJ·kg−1 to 950 kJ·kg−1. Besides, for the comparison between CSTB and STB, it demonstrates that under the condition of 40 °C heat release temperature and 10 °C ambient temperature, ESD of STB is a bit larger than that of CSTB by 47 kJ·kg−1. When ambient temperature drops to 0 °C, ESD of STB decreases to 310 kJ·kg−1, which is 50% lower than that of CSTB. It reveals that the compression process is key to CSTB at lower ambient temperature, and expected to have a desirable performance by regulating sorption kinetics in real application.