Application of coarse-graining for large scale simulation of fluid and particle motion in spiral jet mill by CFD-DEM

Scott, Lewis; Borissova, Antonia; Renzo, Alberto Di; Ghadiri, Mojtaba

doi:10.1016/j.powtec.2022.117962

Cited by 7 publications

(1 citation statement)

References 25 publications

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“…The spiral nozzle insertion method forms a vortex zone inside the fluidized bed, and the fluid forms a vortex structure throughout the entire inner space of the jet mill. Since classification only occurs near the top and bottom walls, making it difficult for large particles to obtain large impact energy in such flow fields [1][2][3]. Carmine et al presented a novel approach to model the micronization of pharmaceutical ingredients at process scales and times, and the proposed approach could be used to estimate the outlet particle size distribution in a short computational time [4].…”

Section: Introductionmentioning

confidence: 99%

CFD simulation of flyash fluidized-bed pulverization with superheated steam

Zhang,

Hong,

Liu

et al. 2024

J. Phys.: Conf. Ser.

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The supersonic pulverization technology uses superheated steam generated by the boiler to generate supersonic airflow through the Laval nozzle, and accelerates the flyash fed into the crushing chamber by the screw feeder, and then the flyash can be crushed in mutual collision and friction process. The present paper conducted CFD simulation of fluidized-bed pulverization with superheated steam, and both the velocity filed and the particle tracks are obtained. Convergence test was performed firstly to verify the numerical results, and three different meshes and several different numbers of particles are employed here to show the average velocity of the particles through a certain horizontal plane. The effect of some key parameters, such as distance between the two opposite nozzles and feeding locations of the flyash to the velocity filed and the particle velocity are also numerically investigated. Results show that, the best distance between the two opposite nozzles of the four-nozzle case is 142 mm and the average particle velocity distribution varies little with the flyash feeding position for the present jet mill model.

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Section: Introductionmentioning

confidence: 99%

CFD simulation of flyash fluidized-bed pulverization with superheated steam

Zhang,

Hong,

Liu

et al. 2024

J. Phys.: Conf. Ser.

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Comparison of sub-grid drag laws for modeling fluidized beds with the coarse grain DEM–CFD approach

Grabowski,

Jurtz,

Brandt

et al. 2023

Comp. Part. Mech.

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Fluidized particulate systems can be well described by coupling the discrete element method (DEM) with computational fluid dynamics (CFD). However, the simulations are computationally very demanding. The computational demand is drastically reduced by applying the coarse grain (CG) approach, where several particles are summarized into larger grains. Scaling rules are applied to the dominant forces to obtain precise solutions. However, with growing grain size, an adequate representation of the interaction forces and, thus, representation of sub-grid effects such as bubble and cluster formation in the fluidized particulate system becomes challenging. As a result, particle drag can be overestimated, leading to an increase in average particle height. In this work, limitations of the system-to-grain ratio are identified but also a dependency on system width. To address this issue, sub-grid drag models are often applied to increase the accuracy of simulations. Nonetheless, the sub-grid models tend to have an ad hoc fitting, and thorough testing of the system configurations is often missing. Here, five different sub-grid drag models are compared and tested on fluidized bed systems with different Geldart group particles, fluidization velocity, and system-to-grain diameter ratios.

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