Measurement of the Thermal Diffusivity of Liquids by the Forced Rayleigh Scattering Method. 3rd Report. Measurement of Molten Salts

The thermal diffusivity of molten KCl has been measured in the temperature range up to 1000°C by the forced Rayleigh scattering method. Through the experimental assessment of appropriate dye materials for high temperature molten salts, the materials employed here were CoCl₂ and NiCl₂ for KCI and K₂[PdCl₆] for NaNO₃ (check measurement at 333°C). In the case of very weak absorbing dye for molten salts, it was found that scattered light superimposed over the diffracted light of interest has to be taken into account to analyze the output voltage signals of a photomultiplier. The accuracy of the measurement is estimated to be ±7% for KCl colored with NiCl₂. The present KCl results show one of the smallest values among other previous data and they are different by a factor of four. The present study demonstrates the promising applicability of this method to high temperature molten salts.