Dynamic simulation and thermochemical characteristics of continuous 1 MWth CaO/CaCO₃ fluidized bed reactor for thermal energy storage system

Thermochemical energy storage, integrated with supercritical carbon dioxide concentrated solar power, offers a highly promising solution for the large-scale deployment of solar energy. The CaO/CaCO₃ reaction system stands out due to its favorable reversible reaction characteristics, high energy density, and potential for long-term storage. However, the design and optimization of an efficient CaO/CaCO₃ fluidized bed reactor remain challenging due to limited dynamic modeling studies that couple heat and mass transfer with chemical kinetics. To address this issue, a dynamic model of a 1 MWth CaO/CaCO₃ fluidized bed reactor was developed in MATLAB by using the finite volume method. It integrated mass transfer, heat transfer, and thermochemical reaction, focusing on the carbonation reaction of CaO. The study systematically investigated the thermochemical behavior and dynamic characteristics of the reactor, and analyzed various key physical parameters affecting its performance. Results indicated that the reactor achieved a CaO conversion of 85.8 % and a thermal efficiency of 87.3 %. Dynamic analysis demonstrated that the supercritical CO₂ inlet temperature significantly affected the reactor's outlet temperature, while variations in particle inlet flow rate had a notable impact on CaO conversion. In contrast, changes in particle inlet temperature had minimal effects. Furthermore, sensitivity analysis revealed that increasing the CO₂ inlet pressure, particle specific surface area, and diffusion coefficient could enhance the heat and mass transfer performance of the reactor. These findings provide valuable insights into the design, modelling, and scale-up of thermochemical energy storage systems, supporting their future advancement and deployment in solar thermal energy systems.