A computational particle–fl uid dynamics (CPFD) model of a fl uidized bed reactor with carbon nanotube (CNT, d p = 485 μm)

particles was established. A drag model and coeffi cient were determined to simulate the hydrodynamic behavior of CNTs

in a fl uidized bed. The drag coeffi cient refl ected the variation in physical properties owing to CNT agglomeration, such as

aggregate size distribution, particle circularity, and apparent density. The Richardson–Davidson–Harrison model with a drag

coeffi cient of 0.17 was chosen based on results on solid holdup distribution. The proposed CPFD model described hydrodynamic

behaviors, such as bed expansion, solid holdup distribution, and relative standard deviation (RSD) of the pressure drop

with gas velocity, and predicted the transition gas velocity between the partial and complete fl uidization regimes. The bed

expansion and RSD gradually increased with increasing gas velocity in the partial fl uidization regime and rapidly increased

at the beginning of the complete fl uidization regime. The increased gas velocity signifi cantly enhanced bed expansion and

particle entrainment, resulting in the formation of large CNT aggregates and a higher solid holdup in the freeboard in the

complete fl uidization regime. The simulated results describe the behavior of CNT aggregates near the bed surface and in the

freeboard region, supporting previous fi ndings in the literature. Uneven local gas fl ows occurred in the bed and freeboard

regions, and the results described the bubbling bed characteristics in the complete fl uidization regime.