Multiphysics coupled modelling of a tube-plate-type packed-bed reactor for CaO/Ca(OH)₂ thermochemical energy storage operated in ‘electricity-in-steam-out’ mode

The reaction system of Ca(OH)₂/CaO has been widely recognized as one of the most promising candidates for thermochemical energy storage (TCES) due to high energy density and low cost. As one upscaled and functional demonstration, our pioneering pilot-scale prototype of a novel ‘electricity-in-steam-out’ packed-bed reactor has practically verified the possible transition from academia to industry. The implementation is highly dependent on the multiphysics coupled model, which is capable of coupling the combined heat transfer, porous medium flow and thermochemical reactions together, and simulating the transient dehydration and hydration processes. The numerical results indicate that the radiation heat transfer could contribute up to 41 % of the total, based on which an equivalent heat conduction sub-model is established and incorporated in the form of variable bulk thermal conductivity, and agreement between simulation and experiment with average relative deviation of 3.55 %/6.71 % for de/hydration process is achieved. Moreover, both the electric heaters and heat-transfer pipes serve bi-functionally as either heat sources or heat transfer enhancers, suggesting they should be arranged considering the different characteristics of de/hydration processes. This work demonstrates a powerful tool for flexible design and comprehensive analysis of practical TCES reactors.