Forced convective heat transfer of solar salt-based Al2O3 nanofluids using lattice Boltzmann method

Abstract

Though solar salt has been used in concentrated solar plants, the small specific heat capacity and low thermal conductivity still set a limitation on further application. A combination with nanoparticles shows potential to overcome these disadvantages. In present work, a freeze-drying method was employed to formulate solar salt-based Al2O3 nanofluids to modify the effective thermal properties. The investigation of forced convective heat transfer was taken by a modified lattice Boltzmann method. The effect of Al2O3 nanoparticle mass fractions on both effective cp and heat transfer performance was analyzed. Results indicate that within the nanoparticle mass fraction range (0–2.0%), cp and heat transfer coefficient increase with the increase of nanoparticle mass fractions. With 2.0 wt% Al2O3, the enhancement on effective cp, heat transfer coefficient and Nusselt are 12.33%, 7.26% and 3.52%, respectively. In the meantime, a comparison between simulation results and Shah-London correlation prediction was carried out and good agreement was obtained.