Study of Heat and Mass Transfer Mechanisms in a Turbulent Fluidized Bed

Abstract

AbstractEnvironmental regulations concerning emission limitations from the use of fossil fuels in large combustion plants have stimulated interest in fluidized bed technologies. Indeed, these latter offer good options for the replacement of obsolete or polluting power plants. Turbulent fluidized bed has been the subject of considerable research and development. However, its description and characteristics still debated and unclear. This work describes heat and mass transfer mechanisms in a turbulent fluidized bed. The modeled system consists of an identical solid particles bed resting on a porous horizontal grid inside a column and a gas circulating through it at a uniform speed in the ascending direction. This study has been conducted using Ansys Fluent software based on EULER-EULER approach for multiphase flows modeling in a two-dimensional geometry and the K-ɛ approach for turbulence modeling. Different particle size and several functions and parameters were used. These functions and parameters were developed in C++ software and were implemented in Fluent software using the user defined function interface. Presented results demonstrate the influence of particle size, drag force and diffusion coefficient on heat transfer. It was found that particle surface temperature increases if particle size increases. These results appear to be consistent with previous works.KeywordsTurbulentFluidized bedParticle sizeCombustionTemperature