Heat-mass transfer, reaction and sintering characteristics in energy carrier for calcium-looping thermochemical energy storage

Abstract

Calcium looping-thermochemical energy storage driven by renewable energy is a promising technology for large-scale long-duration energy storage and industrial decarbonization. However, sintering significantly reduces the energy storage capacity and cycling stability of the energy carrier. In this study, a coupled heat-mass-reaction-sintering model is proposed to investigate the thermochemical behavior and energy storage performance at the particle scale. Extremely high temperature and long residence time are the primary factors aggravating sintering under photothermal. Despite high energy storage efficiency and mild conditions, the prolonged conversion time under electrothermal is not conducive to rapid response applications. For operating parameters at the reactor scale, increasing input power is essential for high reaction rate and energy storage efficiency. However, matching input power and residence time is necessary to mitigate sintering and reduce energy losses. Furthermore, increasing ambient gas velocity and pressure is beneficial for enhancing temperature uniformity at the cost of slowing conversion. For particle parameters, high absorptivity and initial porosity are crucial for high energy storage efficiency and fast conversion. Low porosity caused by sintering can cause CO₂ accumulation, further extending conversion time. Additionally, 0.15–0.25 mm radius range is suitable for rapid energy storage response, while 0.15–0.2 mm radius range is optimal for sintering resistance in long-term operation.