Performance investigation of LiCl·H(2)O-γ-Al(2)O(3) composite materials for low-grade heat storage

In this study, the influences of nano γ-Al(2)O(3) on the thermal storage performance of LiCl were experimentally investigated. The XRD results show that a complex of lithium aluminium oxychloride (LiAlOCl(2)) was formed through the LiCl·H(2)O and γ-Al(2)O(3) composites preparation process. The in situ diffuse reflectance infrared Fourier transform spectroscopy measurement reveals that the addition of γ-Al(2)O(3) accelerated the hydration rate of LiCl composites, concentrated the spectrum utilization range, and promoted the desorption rate of physical adsorbed H(2)O 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-Al(2)O(3) can increase the conversion rate of LiCl·H(2)O to approximately 100% at the hydration time of 1 h and the addition content of γ-Al(2)O(3) at 15 wt%. A maximum heat storage density (HSD) for the LiCl·H(2)O-γ-Al(2)O(3) composite can reach 714.7 kJ kg(LiCl·H(2)O)(−1) in 1 h when the addition content of γ-Al(2)O(3) 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 Al(2)O(3) 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·H(2)O-γ-Al(2)O(3) composite slightly decreased with the increase of nano γ-Al(2)O(3) content.