Temperature dependence of density and thermal conductivity of single molten salts

Low-temperature eutectic region (LTER) of a molten-salt mixture is defined as the temperature range between the melting temperature of the mixture and the highest melting temperature of its components. The melting temperature of a salt mixture is usually lower than that of its components if the mixture presents an eutectic behavior, that is, the temperature in the LTER of a mixture of molten-salts may be below the melting temperature of its components. A single salt may be not in liquid state in this temperature range. The properties of single mixture components in the LTER are often necessary but cannot be directly measured through experiments in calculating the thermophysical properties of salt mixtures such as density, viscosity, thermal conductivity, etc. In this paper, dependence of density and thermal conductivity on temperature is theoretically derived, and applied to experimental data. It is proved that experimental density of single molten salts can be well fitted using theoretical models. Experimentally, thermal conductivity data can be obtained by steady state guarded hot ring method (with annulus cell made of two concentric cylinders), modified hot-wire method or forced Rayleigh scattering method. A selected thermal conductivity dataset obtained using these techniques shows the same temperature dependence predicted by the theoretical model given in the present paper.