Experimental Study of Mixing of Nonspherical Particles in a Vibrated Packed Bed Mixer

Abstract

The effect of the shape of particles on mixing and segregation is studied in a vibrated packed bed mixer. Binary mixtures (unequal sized) of four types of nonspherical glass particles (cube, prolate, oblate, and elongated needle) with different aspect ratios are used alongside spherical particles. The overarching goal is to explore the effect of the nonsphericity of granules (particles > 2 mm) used in the food and pharmaceutical industries. The experimental studies analyze the mixing behavior based on the particle (shape and size) and system (frequency and amplitude) parameters. The results show the existence of a critical vibration intensity (Γ = 4.64) below which there is little mixing. In addition, the axial segregation index (SI) value is also significantly correlated to the random monodisperse packing fraction of coarse particles. The axial SI follows the decreasing trend: cube > sphere > oblate > prolate > elongated needle. Similarly, increasing the fine particles’ angularity from 0 to 0.15, the axial segregation is reduced from 0.40 to 0.24. The nonsphericity of particles reveals the tendency to mix more than spherical particles. These results have important industrial design implications and provide heuristics to reduce segregation by selecting the particle shape.

Experimental Investigation of Segregation in the Dilute Phase Transport of Nonspherical Particles through a Pneumatic Conveying System

“…This mixture that arrives later is rich in large particles owing to their lower acceleration. A similar trend in segregation is observed due to the particle size ratio differences in other systems, such as a fluidized bed solid-mixer, vibrated packed solid-mixer, and horizontal rotating cylinder. − …”

Influence of aspect ratio of ellipsoidal particles on mixing in vibrated packed bed using DEM

“…Vibrating packed bed systems provide a good control to study the shape-induced mixing of ellip-soidal particles. This research extends the work of Yogi et al 10 by studying how different aspect ratios of ellipsoidal particles affect granular mixing in terms of mixing index and the average velocity of particles. The system geometry and particle parameters are identical for the experiment and simulations.…”

“…The schematic of the experimental setup used in this work is illustrated in Figure 2. The container geometry and particle properties are taken from previous work by Yogi et al 10 . Two different sizes of glass particles 3 and 6 mm are filled into the container with random packing.…”

“…However, non-spherical granular materials are commonly used in real-world applications. As a result, in recent years, there has been a significant increase in research on the effects of non-sphericity in granular materials 6,7,8,9,10 . Many industrial processes can be improved by understanding the fundamental behavior of non-spherical granular mixtures.…”

“…Many industrial processes can be improved by understanding the fundamental behavior of non-spherical granular mixtures. Verma et al 6 , Yogi et al 10 and Kumar et al 8 conducted experiments on the impact of particle shape on segregation in fluidized, vibrated packed beds, and rotating cylinder respectively. They discovered that particle shape plays a significant role in determining the extent of segregation in these systems.…”