Numerical Simulation of the Physical–Chemical–Thermal Processes During Hydration Reaction of the Calcium Oxide/Calcium Hydroxide System in an Indirect Reactor

Abstract

The CaO/Ca(OH)2 thermochemical energy storage system can store heat through reversible reactions for long term and transport energy for long distance, and thus can solve the mismatching between energy supply and demand. In this study, a one-dimensional model is developed for the physical–chemical–thermal processes during the hydration reaction of CaO/Ca(OH)2 system in an indirect fixed bed reactor, and the corresponding governing equations are solved by the tridiagonal matrix method with self-developed program parallelized by Message Passing Interface. The characteristics and complicated coupling mechanisms of the vapor flow, heat transfer, mass transport and reaction processes are analyzed. Then effects of inlet pressure, convective heat transfer, reactant porosity, reactant permeability and reactor size on the reaction performance are discussed, respectively. It is found that higher inlet pressure, heat transfer coefficient, permeability and porosity can enhance the heat and mass transfer processes, thus accelerating the reaction efficiently. Finally, the reaction performance under different conditions is comprehensively evaluated by four indicators including the reaction time, average power, temperature plateau duration and standard deviation.