Nano-Porous Structure Change of Carbonate and Oxide as Solid Reactant for Thermal-Energy Storage and Temperature Upgrade

Abstract

Cyclic reaction performances of solid reactants for a CaO-CO₂ chemical heat-pump designed for upgrading and storing high-temperature thermal energy were studied. It was observed that solid reactants prepared using CaCO₃ particles have micro-order pore structure among the particles and nano-order pore structure in the particles. With the proposed model, which is considered the pore structure change during reactions, the numerical analysis suggested that the carbonation and decarbonation rates were determined by micro- and nano- order pore structure changes, respectively. Upon experiments of CaO carbonation and CaCO₃ decarbonation at 923K, the pore volume change correspond to the greater part of the total volume change during decarbonation was observed in the range from 10 to 30 nm of pore radius.