Molten salt thermal conductivity enhancement by mixing nanoparticles

•Thermal conductivity of the molten salt was enhanced by improving mixing of nanoparticle.•Dependency of thermal conductivity on temperature was investigated.•Thermal conductivity dependency on temperature was weak even in the case of the nanofluid. Fluoride molten salts are considered candidate of a coolant nuclear fusion reactors. However, heat transfer performance of the molten salts is not as high as liquid metals. Therefore, it is necessary to enhance thermophysical properties of the molten salts to get higher heat removal efficiency. This study aim is to enhance molten salt thermal conductivity by mixing nanoparticles. We employed molten salt HTS (Heat Transfer Salt), which is a mixed salt of NaNO2, NaNO3 and KNO3, as a surrogate of the fluoride molten salts. We measured the HTS thermal conductivity mixed silicon carbide nanoparticles at from approximately 150–250 °C, and then evaluated a rate of thermal conductivity enhancement. The method to measure the thermal conductivity was a transient hot-wire method. We found that the HTS thermal conductivity increased due to mixing the nanoparticles. In conclusion, it was demonstrated that mixing nanoparticles was able to enhance molten salt thermal conductivity. Moreover, we concluded that, in the present temperature range except near melting point of the sample, an amount of thermal energy that the nanoparticles stored did not significantly change even at the higher temperature.