Molecular dynamics study on thermophysical properties of K2CO3 molten salt-based SiO2 nanofluids using Buckingham potential framework

•Thermophysical properties of K2CO3-SiO2nanofluid were studied by MD simulation within a Buckingham potential framework.•Local structure and energy were analyzed to reveal the mechanism of the enhanced heat capacity of the nanofluids.•A compressed layer is observed around the nanoparticle, in which the cation is closer to the nanoparticle.•The mechanism of the enhanced thermal conductivity of the nanofluids was explored using heat flux decomposition and VDOS. In concentrated solar power (CSP) systems, molten salt plays a vital role as a medium for both storing and transferring heat. This research conducts molecular dynamics (MD) simulations to investigate the thermophysical properties of K2CO3 molten salt-based SiO2 nanofluids within the Buckingham potentialframework. MD results show that the Buckingham potential along with the derived parameters can well reproduce the thermophysical properties of K2CO3 molten salt. At 1.0 wt% of nano-SiO2, the nanofluids achieve a 11.80 % enhancement in specific heat capacity compared with the pure molten salt. The thermal conductivity of molten salt nanofluids is increased as the doping ratio of nano SiO2 is increased. Specifically, when the doping ratio reaches 3.0 wt%, the thermal conductivity is increased by 14.31 % compared with the undoped base salt. It has been found that the enhanced specific heat capacity of nanofluids is primarily resulted from the change in the Coulomb energy due to the addition of the nano-SiO2 and a compression layer surrounding the nanoparticles. Heat flow decomposition of the nanofluid has also shown that its enhanced thermal conductivity is mainly caused by the strengthened nonbonded interactions by adding the nanoparticles.