High-temperature thermal stability of molten salt materials

This paper focuses on thermal stability of molten salts consisting of potassium nitrate, sodium nitrite, sodium nitrate and one kind of additives such as A, B and C at a high temperature. The multi‐component molten salts were prepared by mixing the pure salts, heating statically to the melting state and then cooling to room temperature to form the mixed molten salts. The stability experiments were carried out at 500 and 550°C, and the experiment found that the molten salt with 5% additive A performed better high‐temperature thermal stability and its optimum operating temperature was increased to 550 from 500°C. XRD and DSC analyses indicated that the molten salt with 5% additive A had a lower freezing point and a higher phase change latent heat. Besides, the concentration of NO 2− anion in the molten salt was analyzed and the results showed that the main reaction for the molten salts in air was nitrite thermal oxidation at 500 and 550oC. In addition, the energy used for the oxidation of nitrite would be increased with an increase in additives and the prolonging of reaction time at the same time. Copyright © 2008 John Wiley & Sons, Ltd.