Zheng, H. L., Xianglei; Xuan, Yimin; Song, Chao; Liu, Dachuan; Zhu, Qibin; Zhu, Zhonghui; Gao, Ke; Li, Yongliang; Ding, Yulong. "Thermochemical heat storage performances of fluidized black CaCO3 pellets under direct concentrated solar irradiation," Renewable Energy Vol. 178, 2021, pp. 1353-1369. https://doi.org/10.1016/j.renene.2021.07.026. (https://www.sciencedirect.com/science/article/pii/S0960148121010314)
Abstract: Conventional solar thermochemical heat storage based on indirect surface-heating usually suffers from high heat losses and low solar-chemical efficiency. Here, a different solar thermochemical heat storage system based on direct solar illumination on fluidized black CaCO3 pellets is proposed. A Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model considering irradiation ray tracing, granular flow, heat and mass transfer, and chemical reaction, is built. Black CaCO3 pellets are fabricated via a facile template mixing method, and the solar absorptance is enhanced to 63.9% from 27.9% of traditional pure CaCO3. Effects of gas velocity and irradiative flux on thermochemical heat storage performance in a fluidized volumetric bed are investigated by incorporating measured kinetic and solar absorptance properties of designed black CaCO3 pellets. The peak solar-chemical efficiency reaches a value higher than 43% benefiting from enhanced solar absorptance, higher gas velocity and irradiative flux. This work guides the design of the high-efficiency direct solar thermochemical heat storage system.
Keywords: Thermochemical heat storage; Calcium carbonate; Full-spectrum; Fluidized bed; Direct irradiation