Numerical modeling and experimental validation on the thermal stress inside the three-dimensional porous calcium-based particle for thermochemical energy storage

The solar-driven calcium looping is a very promising high-temperature thermochemical energy storage technology. The calcium-based particles suffers from high thermal stress and is prone to fragmentation in high-flux concentrated solar power systems. Therefore, in this study, calcium carbonate spherical particles with certain hardness were prepared using the extrusion spheronization method, and the real pore structure of calcium carbonate particles was obtained through micro-computed tomography scanning (μ-CT). Next, the displacement and strain of the calcium carbonate particles during the heating process were measured in real-time using optical methods. Integration of displacement vectors in different directions showed that the displacement in the X direction was the dominant direction. Subsequently, numerical simulation was employed to calculate the temperature field and stress field of the calcium carbonate particles with the real pore structure. The results showed that with the increase of heating time, the maximum temperature difference within the particles increased from 6 K to 13 K, and the corresponding maximum thermal stress on the particles increased from 2.13 MPa to 3.87 MPa. Finally, the maximum thermal stress obtained from numerical simulations was compared with experimental results, and the results showed good agreement between the experimental and simulated values, with an error range of 8.93 %–21.64 % and an average error of 16.9 %. The findings are of significant importance for preventing the fracture of high-temperature thermochemical energy storage particles during operation.