Influence of rolling friction on single spout fluidized bed simulation

Euler-Lagrange simulations of fluidized beds of Geldart Group A particles containing different levels of fines are performed in periodic domains with various domain-averaged solid volume fractions. Bubble-like voids readily form when no fines are added. Introducing fines does not reduce bubble sizes if van der Waals force between particles is not accounted for. In contrast, the addition of van der Waals force produces significant changes. With no fines, bubbles are found to be suppressed at sufficiently high solid volume fractions, corresponding to the expanded bed regime for Group A particles. With the addition of fines, bubbles can be suppressed at lower solid volume fractions. With more fines added, bubbles can be suppressed at even lower solid volume fractions. When bubbles are suppressed, the system is found to be in a stable solid-like regime. In this regime, forces on each particle are balanced, and the particle velocity fluctuations are dampened.

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“…31 The two phases are coupled via CFDEMcoupling software. 32 Particle motion is followed by solving Newton's equations of motion:…”

Section: Simulation Methodologymentioning

confidence: 99%

Numerical studies of the effects of fines on fluidization

Özel

Sundaresan

2016

AIChE Journal

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“…is the relative angular velocity [34]. Energy is basically dissipated via frictional damping in sliding and, in collisonal interactions, via the coefficient β = ln(e)/ ln 2 (e) + π 2 , with e the restitution coefficient.…”

Section: Intergrain Forcesmentioning

confidence: 99%

Dynamic induced softening in frictional granular materials investigated by discrete-element-method simulation

et al. 2017

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A granular system composed of frictional glass beads is simulated using the Discrete Element Method. The inter-grain forces are based on the Hertz contact law in the normal direction with frictional tangential force. The damping due to collision is also accounted for. Systems are loaded at various stresses and their quasi-static elastic moduli are characterized. Each system is subjected to an extensive dynamic testing protocol by measuring the resonant response to a broad range of AC drive amplitudes and frequencies via a set of diagnostic strains. The system, linear at small AC drive amplitudes has resonance frequencies that shift downward (i.e., modulus softening) with increased AC drive amplitude. Detailed testing shows that the slipping contact ratio does not contribute significantly to this dynamic modulus softening, but the coordination number is strongly correlated to this reduction. This suggests that the softening arises from the extended structural change via break and remake of contacts during the rearrangement of bead positions driven by the AC amplitude.

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“…Compared with the traditional spouted bed, the total flow rate required to fluidize the particles is reduced with the presence of the background velocity [9]. Lots of experimental efforts have been taken in the past to investigate many important aspects of the spout-fluid bed [10][11][12][13][14][15]: Zhang et al [16,17] experimentally investigated the mixing and segregation behavior in a spout-fluid bed, with the influences of particle size and density. The results show that segregation of solid phase becomes more pronounced with increasing the particle size difference and the segregation pattern is dependent on the mass ratio and density difference between the light and heavy particles.…”

Section: Introductionmentioning

confidence: 99%