Bubbling fluidized beds have been widely used in industrial applications because of its good mass and heat transfer behavior,where the heterogeneous structures such as bubbles are widely present,and these complex structures significantly affect the mass,momentum,and heat transfer as well as chemical reactions in the fluidized bed.The continuum model is selected to simulate the industrial fluidized beds by considering both of the computer cost and efficiency.In order to improve the accurate prediction of the continuum method simulation,it's very important to quantify reasonably the relationship between heterogeneous structures and three transfers/chemical reactions.The structure two-fluid model has been proposed as a novel continuum model,which has taken into account the influence of the heterogeneous structures such as particle clusters in the governing equations and the constitutive relations,therefore,this method is a complete and logically self-consistent in terms of heterogeneous structures.In this study,the structural two-fluid model is extended to the numerical simulation of bubbling fluidized bed:in the deducing the governing equations,the heterogeneous gas-solid system is divided as the particle-dominated emulsion phase and gas-dominated bubble phase,which are defined as two continuous fluids and permeate each other;for closing the constitutive relations,the involved bubble diameter,solid fraction in the emulsion phase and its viscosity have considered the influence of heterogeneous structures such as bubbles by some empirical correlations.As shown in the simulated results,the structural two-fluid model can successfully predict the hydrodynamics characteristics of gas-solid flow in the bubbling beds,thus validating the applicability of the structural two-fluid model in the simulation of bubbling fluidized beds.Moreover,the bubble size as an essential factor has an impact on the interaction between bubble phase and emulsion phase,which leading to the different simulation results with different bubble size correlations.
multiphase flowbubbling fluidized bedmesoscale structurebubblecontinuum model
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