The kinetics research of thermochemical energy storage system Ca(OH)2/CaO

Abstract

Summary As one of the most promising thermochemical energy storage medium, research on the Ca(OH)2/CaO system provides an important way of understanding energy storage/release rates of the entire energy storage system. In this paper, a high-precision thermogravimetric analysis is adopted to investigate thermal decomposition processes of the Ca(OH)2 samples in pure N2 atmosphere at different heating rates. The results demonstrate that during the thermal decomposition process, two weight loss processes respectively occur during 623.15 ~ 773.15 and 873.15 ~ 973.15 K, and the weight loss rates are close to 21% and 2% severally. Multi-heating rate methods are applied to the study of thermal decomposition dynamics. Findings show that the obtained kinetic parameters are related to reaction conversion, heating rate, and the chosen model-methods. To further understand the decomposition mechanism of Ca(OH)2, differential method, integral method, and multiple scanning method are used to deal with the experimental data. Through the most probable mechanism function analysis, under certain experimental conditions, thermal decomposition kinetics model of Ca(OH)2 accords well with the shrinking cylinder mechanism. These conclusions provide theoretical bases for applying the Ca(OH)2/CaO system to the thermochemical energy storage field. Copyright © 2016 John Wiley & Sons, Ltd.