The effect of nano-MgO on thermal properties of ternary chloride fluid

Abstract

Abstract Molten chloride salts are promising candidates for high temperature thermal energy storage. However, the thermal properties of molten salts is of significance for their usage in real applications. In this study, a series of MgO doped chloride salt nano-fluids have been prepared and their thermal properties have been studied. The specific heat capacity (cp) and thermal diffusivity (α) of nano-fluids have been measured by differential scanning calorimeter (DSC) and laser flash analysis (LFA). The results show that the fusion enthalpy of chloride salt with 100nm MgO of 4.5 wt.% was 42.4 J·g-1 higher than pure ternary chloride. The melting point of chloride salt with 60nm MgO of 3.5 wt.% is reduced to 424.75°C. Scanning electron micrographs show that nano-MgO has good dispersibility in ternary chloride .The specific heat capacity of chloride salt with 20nm MgO of 4.5 wt % can increase by at least 28.5% over 480 oC. The MgO obtained by the in-situ method was close to 3.8wt.% of the total content, which result in the increase of thermal diffusivity by 23.5% when the temperature is close to 550°C. The enhanced cp and α of nano-fluids show that doping of nano-MgO has a positive effect on the improvement of the heat transfer performance for chloride salts.