Fluidization in Supercritical Water: Heat Transfer between Particle and Supercritical Water

Supercritical water fluidized bed reactor, which is used to gasify biomass and produce hydrogen, is a new member of fluidized bed family. Forced convection heat transfer between supercritical water and particles is a major basic heat transfer mechanism in supercritical water fluidized bed reactor. The object of this paper was to determine the heat transfer characteristics for a forced convection between a spherical particle and supercritical water (SCW) in a range of pressure from 23 to 27 MPa and temperature from 637 to 697 K. A numerical model fully accounting for thermal physical property variation of SCW has been solved using a finite volume method with Reynolds number up to 200. Comparing with constant property flow, high velocity and temperature gradient in the vicinity of the particle surface were observed when the variable thermal physical property of SCW was incorporated in calculation. Based on the numerical results, a correlation that takes into account the large thermal physical property variation was proposed for predicting Nusselt number.