Numerical study on free convection heat transfer from sphere particle in supercritical water

Free convection heat transfer from particle in supercritical water (SCW) is a major basic heat transfer mechanism in supercritical water fluidized bed (SCEFB). Numerical study on the steady free convection heat transfer from a single sphere particle SCW has been conducted. Both the Boussinesq approximation method and real property model (considering variable specific heat, density viscosity, and conductivity of SCW) are incorporated to simulate the flow and temperature field. Comparing with Boussinesq approximation, high vorticity high temperature gradients, high local Nusselt number, and high heat transfer rate were observed in the vicinity of the sphere surface. The increasing trend of Nusslet number mainly depends on variation of specific heat and conductivity. The relationship between Grashof number and Nusselt number for variable property flow is nearly linear in logarithmic coordinates.