Effect of Multi-Walled Carbon Nano Tubes on Thermal Properties of Nitrate Molten Salts

Energy storage is a key element in energy conservation and efficiency of thermal energy utilization. Among different methods of storing thermal energy, latent heat thermal energy storage (LHTES) systems using phase change materials (PCMs) have been widely used. In this work, composites of multi-walled carbon nanotubes (MWCNTs) and NaNO3-KNO3 binary salt (60: 40 ratio) were mixed with four different weight fractions (0.1, 0.5, 1.0, and 1.5 wt. %) of MWCNTs using the direct synthesis method. The morphology, melting enthalpy, melting point, specific heat, and thermal conductivity were characterized using scanning electron microscope, differential scanning calorimetry, and hot disk analyzer. MWCNTs with concentrations of 0.1 wt. %, 0.5 wt. %, and 1.0 wt.% enhanced the heat of fusion of solar salt to 36.11%, 33.30%, and 10.11% respectively; And enhanced its thermal conductivity by 21.93%, 33.33%, 43.86% and 50.88% with concentration of 0.1 wt. %, 0.5 wt. %, 1.0 wt.%, and 1.5 wt.%, respectively.