Numerical Analysis and Study of Factors Affecting the Hydrodynamic Behavior of a Gas-Solid Bubbling Fluidized Bed with Particle Granular Behavior

Document Type : Original Article

Authors

1 Master's degree, Imam Khomeini International University, Qazvin, Iran

2 Associate Professor, Imam Khomeini International University, Qazvin, Iran

Abstract

In recent years, fluidized bed reactors have attracted much attention due to a number of features such as uniform temperature distribution, proper mixing phases, and high heat transfer rates. The high heat transfer rate in the fluidized bed depends on the hydrodynamic factors of the bubbling bed. Therefore, in this study, the effects of particle diameter variations, the inlet air velocity change, and the drag model alteration on the performance of Geldart Group B particles in a bubbling fluidized bed are examined by studying the mean axial velocity distribution of particles and the mean volume fraction distribution of particles in the bubbling fluidized bed. Thus, the Eulerian multiphase flow approach and the kinetic theory of granular flow are employed in this study. In this regard, particles with the diameters of 500 μm, 530 μm, 570 μm, and 600 μm are considered. As can be seen in the results, increasing the diameter of solid particles from 500 μm to 600 μm decreases the average velocity of the solid particles around the bed core by approximately 45% and increases the accumulation of solid particles in the bed bottom by 14%. Moreover, as the particle diameters increase, an approximate increase in the granular temperature is witnessed. In addition, three different drag models have been studied in this paper. Compared to other drag models, the Syamlal-O'Brien model predicts the lowest downward velocity (negative velocity) near the walls, the lowest upward velocity (positive velocity) near the bed core, and the highest average volume fraction of solid particles. Furthermore, this study has investigated the effect of change in the inlet air velocity. As can be seen in the result of this study, increasing the velocity from 0.550 m/s to 0.587 m/s increases the average velocity of particles around the bed core by approximately 40%.

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References

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Fluid Mechanics & Aerodynamics
Volume 11, Issue 1 - Serial Number 29
October 2022
Pages 115-132

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History

  • Receive Date: 04 February 2022
  • Revise Date: 16 June 2022
  • Accept Date: 19 July 2022
  • Publish Date: 23 August 2022

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