Comprehensive Analysis of Bidisperse Fluidized-Bed Kinetics Under Coupled Heat Transport

Abstract

Fluidized beds operating with bidisperse particle mixtures are integral to numerous industrial processes, including coal gasification, biomass combustion, and catalytic cracking. The complex interplay between particle kinetics and thermal transport in these systems presents significant challenges for process optimization and scale-up. This paper provides a comprehensive investigation into the kinetic behavior of bidisperse fluidized beds under the influence of coupled heat transport mechanisms. By integrating the kinetic theory of granular flow with Eulerian-Eulerian multiphase modeling, this study delineates the precise hydrodynamic and thermal interactions between particles of varying sizes and densities. The research systematically examines segregation and mixing phenomena, emphasizing how localized temperature gradients alter gas viscosity and, consequently, fluidization hydrodynamics. A rigorous methodological framework is established to quantify interphase heat transfer coefficients and particle collision frequencies across a spectrum of operating conditions. The findings reveal that bidisperse mixtures exhibit distinct thermal distribution profiles compared to monodisperse systems, primarily due to the differential drag forces and percolation velocities inherent in disparate particle populations. Furthermore, the introduction of coupled heat transport equations demonstrates that thermal expansion of the fluidizing medium significantly modifies the minimum fluidization velocity of the finer particle fraction, thereby accelerating transient segregation states. These insights offer a robust theoretical and empirical foundation for designing highly efficient multiphase reactors where precise temperature control and uniform mixing are paramount.