Preparation and property measurement of ternary eutectic sodium salt with multiwalled carbon nanotubes

In this study, NaF–NaCl–Na₂CO₃/multi-walled carbon nanotubes (MWCNTs) composites were prepared for high-temperature heat storage to increase the thermal conductivity of base salt. The impact of MWCNTs on the properties was tested. The test results demonstrated a marked improvement in the thermal diffusivity of NaF–NaCl–Na₂CO₃ after the addition of MWCNTs. Particularly, the composite with 1 wt% MWCNTs exhibited the most notable enhancement effect, with a thermal diffusivity of 1.22 mm²/s, representing a 17.5 % increase compared to the base salt. Moreover, the thermal conductivity of the prepared composite can be up to 2.87 W/(m·K), showing a 23.67 % improvement over the base salt. Adding MWCNTs increases the specific heat capacity of NaF–NaCl–Na₂CO₃ by 31.63 %. Additionally, thermal stability analysis demonstrated that NaF–NaCl–Na₂CO₃/MWCNTs composites maintained good thermal stability at 1100 K. Overall, the developed NaF–NaCl–Na₂CO₃/MWCNTs composite exhibited promising potential as a high-temperature heat storage medium.