The solar-driven calcium looping is a very promising high-temperature thermochemical energy storage technology. The calcium-based particle suffers from high thermal stress and is prone to fragmentation in high-flux concentrated solar power systems. Therefore, enhancing the stability of calcium-based particle under high-temperature conditions is of great importance. However, reports on the thermal stress of three-dimensional calcium-based particle in high-temperature thermochemical energy storage are currently scarce. In this study, based on micro-computed tomography (μ-CT), a real structural particle model was reconstructed, and numerical simulation techniques were employed to investigate the influence mechanisms of physical parameters and radiative properties of calcium-based particle on temperature and stress fields. First, using μ-CT technology combined with three-dimensional reconstruction algorithms, a digital three-dimensional porous structure of calcium-based particle was obtained. Subsequently, numerical methods were used to analyze changes in internal temperature and thermal stress under different physical parameters and radiative properties of calcium-based particle. Research indicates that when the specific heat capacity is 856 J/(kg·K), the particle thermal stress reaches a maximum value of 77.3 MPa, whereas at a specific heat capacity of 1256 J/(kg·K), the thermal stress reaches a minimum value of 48.83 MPa; when the absorptivity is 0.7, the thermal stress reaches a maximum value of 92.18 MPa, while at an absorptivity of 0.3, the thermal stress reaches a minimum value of 67.52 MPa. Therefore, lower specific heat capacity and higher absorptivity increase the risk of particle failure. Combining the numerical values of particle safety stress, the research results can provide important guidance for the preparation of high-performance calcium-based particle.
 

Keywords: Calcium looping, Thermochemical energy storage, Thermal stress