Performance investigation of LiCl·H2O-γ-Al2O3 composite materials for low-grade heat storage

• Published in: RSC advances 2023-08, Vol.13 (36), p.24944-24954
• Main Authors: Li, Lin, Zeng, Tao, Huang, Hongyu, Li, Jun, Kobayshi, Noriyuki, Yang, Xiaohu
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Chemistry; Composite materials; Fourier transforms; Heat storage; Hydration; Lithium chloride; Particulate composites; Thermal conductivity; Thermal storage; Transitional aluminas
• ISSN: 2046-2069
• DOI: 10.1039/d3ra03835a

In this study, the influences of nano γ-Al2O3 on the thermal storage performance of LiCl were experimentally investigated. The XRD results show that a complex of lithium aluminium oxychloride (LiAlOCl2) was formed through the LiCl·H2O and γ-Al2O3 composites preparation process. The in situ diffuse reflectance infrared Fourier transform spectroscopy measurement reveals that the addition of γ-Al2O3 accelerated the hydration rate of LiCl composites, concentrated the spectrum utilization range, and promoted the desorption rate of physical adsorbed H2O and low-frequency structural –OH in the materials. The highest specific surface area of the composite is 34.5 times higher than that of pure LiCl. The addition of γ-Al2O3 can increase the conversion rate of LiCl·H2O to approximately 100% at the hydration time of 1 h and the addition content of γ-Al2O3 at 15 wt%. A maximum heat storage density (HSD) for the LiCl·H2O-γ-Al2O3 composite can reach 714.7 kJ kgLiCl·H2O−1 in 1 h when the addition content of γ-Al2O3 was 15%wt and its water uptake can reach 0.26 g g−1 in 1 h. It also can be found that the addition of Al2O3 in LiCl resulted in a decrease of the activation energy from 90.89 kJ mol−1 to 79.76 kJ mol−1. However, the thermal conductivity of the LiCl·H2O-γ-Al2O3 composite slightly decreased with the increase of nano γ-Al2O3 content.