Research on high temperature thermal stability and safety of two types of composite inorganic phase change thermal storage materials

In this paper, nitrate (KNO₃, NaNO₃) and carbonate (Li₂CO₃, K₂CO₃, Na₂CO₃ and CaCO₃), which are composite inorganic phase change thermal storage materials suitable for industrial thermal storage, non-toxic and less corrosive, are used as phase change components, respectively. The thermal properties (melting point, latent heat) of 4 different ratios of nitrate phase change components and 6 different ratios of carbonate phase change components were studied, and a distribution ratio of molten salt phase change components was selected respectively. Using the principle of porous carrier adsorption, two types of composite molten salt thermal storage materials with the best ratio were prepared. The ease of decomposition of the thermal storage materials in different media atmospheres (Ar and air) was analyzed. TG-DSC-MS tested high temperature thermal decomposition products show that the composite nitrate thermal storage materials have stable physical and chemical properties and good safety when storing thermal at medium temperature (300℃), but they are easy to decompose NO and high temperature (500℃) or higher. NO₂ and air atmosphere are more likely to generate toxic gases, and composite carbonate thermal storage materials are more likely to generate CO in air than Ar, which affects the safety of the thermal storage process.