Effects of interface layer on the thermophysical properties of solar salt-SiO2 nanofluids: A molecular dynamics simulation

The microstructure and behaviors of the interface layer around the nanoparticle are strongly related to the overall thermophysical properties of molten salt-based nanofluids (MSBNFs). Understanding this link may enable the advanced heat transfer fluid (HTF) for concentrated solar power and other applications. In this study, a molecular dynamics (MD) model for solar salt (60 wt% NaNO3/40 wt% KNO3)-SiO2 nanofluid system is developed to estimate the characteristics of the interface layer and their effects on the overall specific heat capacity (SHC) and effective thermal conductivity (ETC) of MSBNFs. The results show that the SHC and thermal conductivity (TC) of the interface layer in MSBNFs are, respectively, 1.44-1.85 and 1.05-1.97 times higher than those of pure solar salt. The SHC of the interface layer has a significant effect on the overall SHC of the MSBNFs, but the interface layer is not the dominant influencing factor for the ETC enhancement of MSBNFs and thus has less effect on the overall ETC.