Performance of thermochemical energy storage of a packed bed of calcium hydroxide pellets

Abstract

Thermochemical energy storage (TCES) using reversible gas‐solid reactions is a promising technology owing to the high energy density and capability of long‐term storage. TCES using a calcium oxide/calcium hydroxide/water (CaO/Ca(OH) 2 /H 2 O) reaction system has attracted considerable attention because of the low material cost and environmental friendliness of the reactants. Previous experimental studies have focused on the TCES performances of packed beds of calcium oxide/calcium hydroxide powder. However, pelleted materials can be more favorable than powdered materials from a practical viewpoint. The aim of this study is to evaluate the performance of TCES of a packed bed of calcium oxide/calcium hydroxide pellets. In this work, a total of 60 g of calcium hydroxide pellets (diameter of 1.9 mm and length of 2‐10 mm) was evaluated using a 100‐W scale packed bed reactor. The heat storage density of the bed was 1.0 MJ L‐bed −1 , and an average heat output rate of 0.71 kW L‐bed −1 was observed for the first 10 minutes under a hydration pressure of 84.6 kPa. The stability of the reaction conversion of the bed was demonstrated during 17 cycles of experiments.