Abstract
Solid spherical shells of mm-order diameter can be applied in lightweight structural materials, buoyant catalytic agents, high-performance solid fuels and artificial organs. A device for sequential production of solid spherical shells using liquid-liquid-gas systems is comprised of a cylindrical container containing two immiscible liquids and a gas injection nozzle at the center of the bottom. By controlling the gas flow and the temperature field of the two liquid layers, liquid spherical shells are formed at the interface between the two immiscible liquids and they solidify during the upward motion. For stable production, it is necessary to correctly estimate the thermo-fluid flow and to control the temperature field in the two liquid layers with high accuracy. To develop a device for sequential production of solid spherical shells, natural convection heat transfer in the two immiscible liquid layers in the cylindrical container was studied. By solving the incompressible Navier-Stokes equations and the energy equations for the upper and lower liquids, the flow patterns and thermal field of the two liquid layers were quantitatively investigated. Suitable conditions for the sequential production of solid spherical shells were determined.
