Experimental study of local solid volume fraction fluctuations in a liquid fluidized bed: Particles with a wide range of stokes numbers

2021 ◽  
Vol 135 ◽  
pp. 103348
Author(s):  
Maedeh Marefatallah ◽  
David Breakey ◽  
R. Sean Sanders
Keyword(s):  
Experimental Study ◽  
Fluidized Bed ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Wide Range

Simulation Studies of Gas-Solid in the Riser of a Circulating Fluidized Bed

2005 ◽  
Author(s):  
Ahmad Hussain ◽  
Farid Nasir Ani ◽  
Amer Nordin Darus ◽  
Azeman Mustafa ◽  
Arshad A. Salema
Keyword(s):  
Gas Phase ◽  
Fluidized Bed ◽  
Turbulence Model ◽  
Circulating Fluidized Bed ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Design Parameters ◽  
Cfd Model ◽  
End Effects ◽  
Wide Range

A numerical parametric study was performed on the influence of various riser exit geometries on the hydrodynamics of gas-solid two-phase flow in the riser of a Circulating Fluidized Bed (CFB). A Eulerian continuum formulation was applied to both phases. A two fluid framework has been used to simulate fully developed gas-solid flows in vertical riser. A two dimensional Computational Fluid Dynamics (CFD) model of gas-particle flow in the CFB has been investigated using the code FLUENT. The turbulence was modeled by a k-ε turbulence model in the gas phase. The simulations were done using the geometrical configuration of a CFB test rig at the Universiti Teknologi Malaysia (UTM). The CFB riser column has 265 mm (width), 72 mm (depth) and 2.7 m height. The riser is made up of interchangeable Plexiglas columns. The computational model was used to simulate the riser over a wide range of operating and design parameters. In addition, several numerical experiments were carried out to understand the influence of riser end effects, particle size, gas solid velocity and solid volume fraction on the simulated flow characteristics. The CFD model with a k-ε turbulence model for the gas phase and a fixed particle viscosity in the solids phase showed good mixing behaviour. These results were found to be useful in further development of modeling of gas solid flow in the riser.

A Sharp Interface Direct Forcing Immersed Boundary Approach for Fully Resolved Simulations of Particulate Flows

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Jianming Yang ◽  
Frederick Stern
Keyword(s):  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Density Ratio ◽  
Sharp Interface ◽  
Immersed Boundary ◽  
Particulate Flows ◽  
Order Accuracy ◽  
Wide Range ◽  
Direct Forcing ◽  
Coarse Grids

In recent years, the immersed boundary method has been well received as an effective approach for the fully resolved simulations of particulate flows. Most immersed boundary approaches for numerical studies of particulate flows in the literature were based on various discrete delta functions for information transfer between the Lagrangian elements of an immersed object and the underlying Eulerian grid. These approaches have some inherent limitations that restrict their wider applications. In this paper, a sharp interface direct forcing immersed boundary approach based on the method proposed by Yang and Stern (Yang and Stern, 2012, “A Simple and Efficient Direct Forcing Immersed Boundary Framework for Fluid-Structure Interactions,” J. Comput. Phys., 231(15), pp. 5029–5061) is given for the fully resolved simulations of particulate flows. This method uses a discrete forcing approach and maintains a sharp profile of the fluid-solid interface. It is not limited to low Reynolds number flows and the immersed boundary discretization can be arbitrary or totally eliminated for particles with analytical shapes. In addition, it is not required to calculate the solid volume fraction in low density ratio problems. A strong coupling scheme is employed for the fluid-solid interaction without including the fluid solver in the predictor-corrector iterative loop. The overall algorithm is highly efficient and very attractive for simulating particulate flows with a wide range of density ratios on relatively coarse grids. Several cases are examined and the results are compared with reference data to demonstrate the simplicity and robustness of our method in particulate flow simulations. These cases include settling and buoyant particles and the interaction of two settling particles showing the kissing-drafting-tumbling phenomenon. Systematic verification studies show that our method is of second-order accuracy on very coarse grids and approaches fourth-order accuracy on finer grids.

Experimental study on a new gas–liquid separator for a wide range of gas volume fraction

2020 ◽  
Vol 160 ◽  
pp. 561-570 ◽  
Author(s):  
Xiaobo Zeng ◽  
Guangming Fan ◽  
Junxiu Xu ◽  
Antai Liu ◽  
Yifan Xu ◽  
...  
Keyword(s):  
Experimental Study ◽  
Volume Fraction ◽  
Wide Range ◽  
Gas Volume Fraction ◽  
Gas Volume ◽  
Liquid Separator

Hydrodynamics of Multiple Jet Systems in a 2D Gas Solid Fluidized Bed

2012 ◽  
Author(s):  
Steven L. Brown ◽  
Brian Y. Lattimer
Keyword(s):  
Fluidized Bed ◽  
Digital Image Analysis ◽  
Particle Image ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Particle Model ◽  
Discrete Particle ◽  
Image Velocimetry ◽  
Discrete Particle Model ◽  
Single Jet

An experimental 2-D fluidized bed was developed to study gas-solid hydrodynamics. The effects of multiple jet systems were examined using Particle Image Velocimetry (PIV) combined with Digital Image Analysis (DIA). Flow regimes were classified through pressure drop spectral analysis. The combination of these non-intrusive techniques allowed for the development of a solid volume fraction correlation. The experimental results show new void fraction regimes of multiple interacting jets. Jet systems combined to promote gas solid mixing and decrease particle dead zones within the bed. It was determined that the validation of multiple jet Discrete Particle Model simulations cannot be exclusively confirmed from single jet studies.

CFD Simulation of Heat Transfer in Fluidized Bed Reactor

2014 ◽  
Vol 493 ◽  
pp. 267-272
Author(s):  
I. Nyoman Suprapta Winaya ◽  
I. Made Agus Putrawan ◽  
I. Nyoman Gede Sujana ◽  
Made Sucipta
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Navier Stokes ◽  
Velocity Variation ◽  
Navier Stokes Equation ◽  
Program Language ◽  
The Heat Transfer Coefficient

This study aims to predict heat transfer from a heated bed in a gas fluidized bed using Syamlal-OBrien drag coefficient. Discrete particles model with the Navier-Stokes equation and Eulerian multiphase are used to approach heat transfer simulation. Coefficient of heat transfer which is related to Nusselt Number and volume fraction are calculated using Gunn model which was compiled from C++ program language. The effect of fluidization velocity variation on the heat transfer coefficient comes to the fore, indicating the heat transfer and solid volume fraction at the bed height are very dependent. Contour of solid volume fraction and temperature distribution are also presented.

scholarly journals Application of Particle Imaging Method for Measurement of Solid Volume Fraction in Carbon Nanotube Particles Fluidized Bed

2018 ◽  
Vol 7 (3.33) ◽  
pp. 85 ◽  
Author(s):  
Sung Won Kim ◽  
. .
Keyword(s):  
Carbon Nanotube ◽  
Fluidized Bed ◽  
Volume Fraction ◽  
Particle Density ◽  
Solid Volume Fraction ◽  
Fixed Bed ◽  
Apparent Volume ◽  
Previous Method ◽  
Imaging Method ◽  
Particle Imaging

Solid volume fraction in the carbon nanotube (CNT) fluidized bed reactors is an important parameter which is responsible of fluidization quality and the design of reactor. The solid volume fraction can be obtained from the pressure drop across the bed with the information of gas and particle densities. However, previous method such as the Hg-porosimetry for the measurement of the particle density did not adequately draw the solid volume fraction of the CNT aggregates with entangled nanotubes network. A new method to measure the apparent particle density of the CNT aggregates was proposed to calculate the solid volume fraction in the CNT fluidized bed. The density of the vertically aligned CNT particle was measured based on the apparent volume by shape analysis using two dimensional imaging. The solid fraction based on imaging method showed a significant value of 0.69 for the fixed bed, which describes well the entangled structure of the CNT aggregates. The distribution of solid volume fraction in the CNT fluidized bed with variation of gas velocity was determined based on the imaging method. The method was verified by applying the obtained values to the Richardson-Zaki equation on the bed expansion in the fluidized bed.  

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