Relationship between flow structure and transfer coefficients in fast fluidized beds

In this paper, the relationships between the bed structural parameters and momentum transfer, mass transfer and heat transfer in fast fluidized beds are analyzed for Geldart A or B particles. The influence of dispersion and aggregation of particles on the mass transfer coefficient and heat transfer coefficient is discussed. The equations for calculating the drag force coefficient, mass transfer coefficient and heat transfer coefficient in fast fluidized beds are developed based on eight structural parameters (U-fd, U-fc, U-pd, U-pc, d(c), f, epsilon(d) and epsilon(c)) of heterogeneous beds. which can be solved by the Energy-Minimization Multi-Scale (EMMS) model. The drag force has been calculated based on the local bed structural parameters and the calculated solids flux and solids concentration are compared with the experimental data in the literature. For the heat transfer and mass transfer, the averaged bed structural parameters are employed to calculate the averaged heat transfer and mass transfer coefficients, and the results are compared with the experimental data from the literature. The simulating results are in good agreement with experimental data. (C) 2010 Elsevier B.V. All rights reserved.