Natural convection heat transfer for eutectic binary nitrate salt based Al2O3 nanocomposites in solar power systems

Molten salts are widely used as thermal energy storage materials in a concentrated solar plant. In these thermal storage systems, natural convection heat transfer for molten salts is important for both energy storage and transfer, however the research on nature convection heat transfer is quite limited. In present work, the natural convection heat transfer for eutectic binary nitrate salt based Al2O3 nanocomposites was numerically simulated using a two-phase lattice Boltzmann model. Various interactions affecting the distribution of nanoparticles were considered in the simulation. The effects of the nanoparticle mass fraction (0-2.0%) and Rayleigh number (104-108) on natural convection heat transfer were also analyzed. Results indicated that natural convection heat transfer increased with increasing the Ra. With the addition of nanoparticles, natural convection heat transfer decreased at low Ra numbers but increased at high Ra numbers. Among all interaction forces considered in this study, the temperature difference driving force FS was much larger than other forces, which means the nanoparticle distribution was mainly influenced by FS.