Thermochemical storage performance of a packed bed of calcium hydroxide composite with a silicon-based ceramic honeycomb support

Abstract

The thermal decomposition of calcium hydroxide (Ca(OH)2) into calcium oxide (CaO) and water vapor has been suggested as a reversible gas–solid reaction suitable for thermochemical energy storage. This study aims to develop a composite material to enhance the heat transfer in a reaction bed. We focus on a novel material using CaO/Ca(OH)2 and a ceramic honeycomb support composed of silicon carbide and silicon. A laboratory-scale evaluation of the thermochemical storage performance of the composite using honeycomb support has not been sufficiently reported in the literature. In this study, a 100 W-scale packed bed reactor was used to evaluate the performance of the composite. We found that the composite had a volumetric energy density of 0.76 MJ L-bed−1 and exhibited a heat output rate of 1.6 kW L-bed−1 (for the first 5 min at the highest hydration pressure of 85 kPa), which was 1.8 times higher than the heat output rate previously reported for a pure Ca(OH)2 pellet bed. The composite also retained its high reactivity during repetitive reactions. Therefore, it was concluded that the composite using the ceramic honeycomb support is practically more useful for thermochemical energy storage than conventional pure CaO/Ca(OH)2 materials.