Particle-scale study of coupled physicochemical processes in Ca(OH)₂ dehydration using the lattice Boltzmann method

Fundamental understanding of coupled physicochemical processes is crucial for improving the heat storage/release performance of thermochemical heat storage systems. In this study, for the first time a coupled lattice Boltzmann model is developed to simulate the particle-scale physicochemical processes during Ca(OH)₂ dehydration, including fluid flow, heat transfer, vapor mass transport and chemical reaction. The dehydration processes of a single Ca(OH)₂ particle, a single particle with coated ceramic shell and packed particles are studied, and thorough parametric studies are performed. The results show that the dehydration reaction rate of a single particle is mainly determined by the temperature and Ca(OH)₂ concentration. Introducing more micro-pores or meso-pores into the particle is favorable to achieve quicker heat storage, but at the cost of lower energy density. Increasing the Reynolds number from 0.3 to 3 or increasing the inlet temperature by 50 K can shorten the reaction time t_c by at least 33.8%. Dedicate design of the shell coated on the particle can enhance the dehydration process with t_c decreased by 3.5%. The underlying heterogenous structures greatly affect the reaction rate of packed particles, and local cracks should be prevented to achieve fast and stable heat storage response.