CFD modeling of gas-fluidized beds with a bimodal particle mixture

AIChE Journal ◽  
2001 ◽  
Vol 47 (6) ◽  
pp. 1292-1302 ◽  
Author(s):  
B. G. M. van Wachem ◽  
J. C. Schouten ◽  
C. M. van den Bleek ◽  
R. Krishna ◽  
J. L. Sinclair
Keyword(s):  
Fluidized Beds ◽  
Cfd Modeling ◽  
Particle Mixture ◽  
Gas Fluidized Beds

Gas‐Fluidized Beds

2021 ◽  
pp. 311-345
Keyword(s):  
Fluidized Beds ◽  
Gas Fluidized Beds

scholarly journals Experimentally-assessed multi-phase CFD modeling of segregating gas-solid fluidized beds

2021 ◽  
Author(s):  
Mohamed Sobhi Alagha ◽  
Pal Szentannai
Keyword(s):  
Fluidized Beds ◽  
Cfd Modeling ◽  
Multi Phase

Expulsion of particles from a buoyant blob in a fluidized bed

1994 ◽  
Vol 278 ◽  
pp. 63-81 ◽  
Author(s):  
G. K. Batchelor ◽  
J. M. Nitsche
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Particle Concentration ◽  
Small Concentration ◽  
Numerical Calculations ◽  
Significant Feature ◽  
Average Particle ◽  
Remarkable Property ◽  
Gas Fluidized Beds ◽  
Secondary Instabilities

It is a significant feature of most gas-fluidized beds that they contain rising ‘bubbles’ of almost clear gas. The purpose of this paper is to account plausibly for this remarkable property first by supposing that primary and secondary instabilities of the fluidized bed generate compact regions of above-average or below-average particle concentration, and second by invoking a mechanism for the expulsion of particles from a buoyant compact blob of smaller particle concentration. We postulate that the rising of such an incipient bubble generates a toroidal circulation of the gas in the bubble, roughly like that in a drop of liquid rising through a second liquid of larger density, and that particles in the blob carried round by the fluid move on trajectories which ultimately cross the bubble boundary. Numerical calculations of particle trajectories for practical values of the relevant parameters show that a large percentage of particles, of such small concentration that they move independently, are expelled from a bubble in the time taken by it to rise through a distance of several bubble diameters.Similar calculations for a liquid-fluidized bed show that the expulsion mechanism is much weaker, as a consequence of the larger density and viscosity of a liquid, which is consistent with the absence of observations of relatively empty bubbles in liquid-fluidized beds.It is found to be possible, with the help of the Richardson-Zaki correlation, to adjust the results of these calculations so as to allow approximately for the effect of interaction of particles in a bubble in either a gas- or a liquid-fluidized bed. The interaction of particles at volume fractions of 20 or 30 % lengthens the expulsion times, although without changing the qualitative conclusions.

Arguments on heat transfer in gas fluidized beds

1993 ◽  
Vol 48 (4) ◽  
pp. 761-770 ◽  
Author(s):  
O. Molerus
Keyword(s):  
Heat Transfer ◽  
Fluidized Beds ◽  
Gas Fluidized Beds

Modeling Approaches to Accurately Predict Minimum Fluidization Characteristics of Gas-Solid Fluidized Beds

2012 ◽  
Author(s):  
Santhip Krishnan Kanholy ◽  
Francine Battaglia
Keyword(s):  
Binary Mixtures ◽  
Fluidized Beds ◽  
Solid Phase ◽  
Cfd Modeling ◽  
Particle Interactions ◽  
Dead Zones ◽  
Modeling Approaches ◽  
Minimum Fluidization ◽  
Computational Fluid Dynamics Cfd ◽  
Eulerian Modeling

The hydrodynamics of fluidized beds involving gas and particle interactions are very complex and must be carefully considered when using computational fluid dynamics (CFD). Modeling particle interactions are even more challenging for binary mixtures composed of varying particle characteristics such as diameter or density. One issue is the presence of dead-zones, regions of particles that do not fluidize and accumulate at the bottom, affecting uniform fluidization. In Eulerian-Eulerian modeling, the solid phase is assumed to behave like a fluid and the presence of dead zones are not typically captured in a simulation. Instead, the entire bed mass present in an experiment is modeled, which assumes full fluidization. The paper will present modeling approaches that account for only the fluidizing mass by adjusting the initial mass present in the bed using pressure drop and minimum fluidization velocity from experiments. In order to demonstrate the fidelity of the new modeling approach, different bed materials are examined. Binary mixture models are also validated for two types of mixtures consisting of glass-ceramic and ceramic-ceramic compositions. It will be shown that adjusting the mass in the modeling of fluidized beds best represents the measured quantities of an experiment for both single-phase and binary mixtures.

Time-Series Analysis of Eulerian Density Fluctuations in Gas Fluidized Beds

2004 ◽  
Vol 43 (18) ◽  
pp. 5776-5782 ◽  
Author(s):  
Clay R. Sutton ◽  
John C. Chen
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
Fluidized Beds ◽  
Density Fluctuations ◽  
Series Analysis ◽  
Gas Fluidized Beds

A numerical study of the bubble induced pressure fluctuation in gas-fluidized beds

2017 ◽  
Vol 314 ◽  
pp. 387-399 ◽  
Author(s):  
Yuli Zhang ◽  
Rui Xiao ◽  
Mao Ye ◽  
Zhongmin Liu
Keyword(s):  
Pressure Fluctuation ◽  
Fluidized Beds ◽  
Numerical Study ◽  
Gas Fluidized Beds
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