Modeling and identification of the hydration process in a CaO/Ca(OH)2-based heat storage system

Thermochemical energy storage systems are promising for storing excess energy produced by renewable sources. Of particular interest and the focus of this paper is a specific application based on the reaction pair CaO and H2O. Working towards a model based controller for the reactor storage system, all of the ongoing processes need to be modeled. This publication establishes a model for the hydration process, where heat is recovered from the exothermic reaction of CaO and liquid H2O. The derivations are based on mass and enthalpy balance equations for the reactor and the cooling water. This yields a simple reactor system model, for which some parameters are unknown and need to be identified. For this, an optimization is set up. Additionally, the parameter sensitivity of the model outputs is analyzed. The simulation results with the identified parameters illustrate that the model is able to predict the measurements well. The sensitivity results coincide with the identification variance for the estimated parameters.