Characterization of nanoparticle agglomerate motion based on the TEMOM method

Abstract

The investigation of nanoparticle agglomerates' dynamic behavior within fluidized beds constitutes a pivotal research avenue within the domains of aerosols and multiphase flows. Within this inquiry, the Thermo-Electrical Model of Moving Particle (TEMOM) is employed to scrutinize the efficacy of three distinct models, namely, the Sectional Moving Mesh (SMM), Quadrature Method of Moments (QMOM), and TEMOM itself, in elucidating particle dynamics within a fluidized bed. The findings underscore the superiority of the TEMOM model in congruence with experimental data about the simulation of bed pressure drop and expansion rate. Initially, during the phase of particle fluidization, particles ascend in a bulging configuration, engendering cyclic motion in conjunction with the descending particles along the walls. Over time, the particles attain a state of stable fluidization, manifesting a tendency towards the stabilization of agglomerated bulk fluidization distribution, albeit with the persistence of stratification phenomena. Within the bed's central region, particle agglomerate velocity attains prominence, with the discernible manifestation of Brownian condensation. Moreover, the continuous occurrence of agglomeration and fragmentation processes within the fluidized bed, particularly along the mid-bed wall, where aggregate diameter and axial velocity register higher values, is noted. The scrutiny of moment characteristics across each order of the particle phase elucidates the influence of particle number density on M₀, M₁, and M₂ moments, with the variation in particle number density directly impinging upon particle motion and agglomeration dynamics. After the attainment of a stable fluidization state by the fluidized bed, the moments' values for each particle order exhibit steady fluctuations, thereby reflecting the distributional and dynamic attributes of particles within the bed.