Ternary Molten Salt Heat Transfer Fluids for Energy Applications

One of the major impediments of current energy applications is the availability of an economical and reliable heat transfer fluid. Such applications include concentrated solar power, gas processing, petrochemicals, nuclear, and other high-temperature processes. Organic heat transfer fluids currently in use have limitations approaching 390°C, and other salt-based fluids have rather high freezing temperatures. Ternary nitrate salts have the potential to operate at high temperatures while maintaining low freezing temperatures. Mixtures of various concentrations of LiNO₃-NaNO₃-KNO₃ salts and their properties have been investigated. For various LiNO₃-NaNO₃-KNO₃ compositions, specific heat, latent heat, and viscosity are reported at various temperatures. Phase diagrams have also been predicted for the LiNO₃-NaNO₃-KNO₃, CsNO₃-NaNO₃-KNO₃, and CsNO₃-LiNO₃-KNO₃ systems using mathematical modeling and the results are encouraging. The results presented in this work are expected to make a significant impact on the development of economical and practical ternary nitrate mixtures in energy applications.