Experimental and numerical study of natural convection in bottom-heated cylindrical cavity filled with molten salt nanofluids

This paper combines numerical and experimental to study the heat transfer by free convection for nanofluids of molten salt within a cavity with cylindrical shape which is heated at the bottom and releases heat at the top. The aim is to acquire the free convection laws for nanofluids of molten salt in a cylindrical cavity. It is found that after adding nanoparticles, the molten salts have lower viscosity, higher flow velocity and higher heat transfer rate, and therefore, the free convection heat transfer is enhanced. Meanwhile, nanofluids Nusselt number is larger than that of the molten salts at the same Rayleigh number. In addition, as the classical Garon's equation cannot provide good predictions of free convection heat transfer for the nanofluids of molten salt, this paper establishes a free convection equation for the nanofluids of molten salt in a cylindrical cavity. This equation is able to predict with an error less than 20% the experimental results. Therefore, the findings can provide a basis for engineering applications of nanofluids and for designing optimal systems of heat stockpile with a single tank.