Impact on thermophysical properties of solar salt with different concentrations of SiC nanoparticles for thermal energy storage system

Enhancement of thermophysical properties of molten salt-based nanofluids is essential to reduce the geometric size and increase the energetic-exergetic efficiency of the thermal energy storage system. Moreover, the thermophysical properties of nanoparticles dispersed molten salt remain unclear, especially the anomalous enhancement of specific heat capacity (Cp). In the present study, the different concentrations (0.5, 1.0 and 2.0 wt%) of silicon carbide nanoparticles (SiC-NPs) dispersed solar salt (i.e., SiC nanosalt) were prepared using the wet chemical method, and their thermophysical properties were evaluated using various differential techniques. The crystalline structure of the SiC-NPs was analysed and confirmed using an X-ray diffractometer (XRD). Further, the size (diameter = 30.61 nm) and shape were identified in the transmission electron microscope (TEM). The differential scanning calorimetry (DSC) analysis was carried out for the prepared SiC nanosalt and found the average specific heat capacity enhancement for 1.0 wt% SiC nanosalt is 14.4 % and 8.1 % in solid (50 degrees C-200 degrees C), and liquid (250 degrees C-350 degrees C) phases, which is 8.7 % and 3.3 % higher than 0.5 wt% and 2.0 wt%. Further, the scanning electron microscope (SEM) technique was conducted for different wt% of SiC and found random dispersion (for 0.5 wt%), better dispersion (for 1.0 wt%), and agglomeration (for 2.0 wt%). From the combined result of DSC and SEM, the optimal weight loading of SiC-NPs was identified as 1.0 wt%. The thermal conductivity was measured for the prepared sample, and it was found that a thermal conductivity of 2.0 wt% is 8.85 % higher than solar salt. Finally, the thermal stability of the nanosalt was tested in thermogravimetric analysis (TGA), and it found that the maximum weight presence for the maximum wt% of SiC is 92.8 %, which resulted in the weight loss of the SiC nanosalt is similar to solar salt.