Identification of the Spouted Bed Flow Regime by Simulation and Experimental Data

2008 ◽  
Vol 591-593 ◽  
pp. 329-334 ◽  
Author(s):  
R.O. Lourenço ◽  
Kássia Graciele dos Santos ◽  
Valéria V. Murata ◽  
Claudio Roberto Duarte ◽  
Humberto Molinar Henrique ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Flow Regimes ◽  
Visual Observation ◽  
Circulation Rate ◽  
Multiphase Model ◽  
Spouted Bed ◽  
Spouted Beds ◽  
Experimental Apparatus

The particle circulation rate and gas–solid contacting efficiency are important parameters for the project of spouted beds, applied in many industrial processes. Due to the restrictions found in the identification of flow regimes through visual observation, new techniques have been developed to obtain a better gas and particle dynamics description, necessary for the evaluation of these parameters. One of these techniques has been the CFD simulation. In this work the pattern of solids and gas flows in a spouted bed was numerically simulated using a 3D Eulerian multiphase model. Soybean particles had been used in the attainment of data of pressure drop fluctuation and power spectrum as a function of gas velocity in an experimental apparatus. The 3D simulated solids volume fraction profiles allow the identification of the flow regimes showing a good agreement with the experimental data.

Mixture of Particles' Influence in Computer Simulations of a Spouted Bed

2010 ◽  
Vol 660-661 ◽  
pp. 448-453 ◽  
Author(s):  
D.A. Santos ◽  
I. Petri Junior ◽  
Marcos A.S. Barrozo ◽  
Claudio Roberto Duarte
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Fluid Dynamic ◽  
Computational Simulation ◽  
Particle Interaction ◽  
Multiphase Model ◽  
Spouted Bed ◽  
Air Concentration ◽  
Spouted Beds ◽  
Full Plane

This article aims to assess the influence of the way of simulating monoparticles as just monoparticles or as a mixture of particles, the latter, unlike the first, considering the effect of particle-particle interaction. The Eulerian–Eulerian multiphase model is used in the computational simulation of fluid dynamics of spouted beds and compared with experimental data. A half column of cylindrical spouted bed with a full plane glass attached to the front open surface of the bed as the transparent window was used for observation and photographing. Images of solid flows were recorded using a high speed camera (2000 frames per second). Glass beads with a diameter of 0.00368, 0.005 and 0.00252 mm are used as bed material. The simulated characteristic fluid dynamic curves of spouted bed for 0.15 m static bed heights (Ho) were obtained with good agreement with experimental data when the monoparticles was simulated as a mixture of particles with mixture’s percentage of 50%. The same occurred for the simulation of vertical velocities of particles profile, that is, when the monoparticles was simulated as a mixture of particles with mixture’s percentage of 50% we observed a more approach to the experimental data. It was also observed that the air concentration distribution seem to be independent of the changing of the composition.

Simulation of Spouted Bed Using a Eulerian Multiphase Model

2005 ◽  
Vol 498-499 ◽  
pp. 270-277 ◽  
Author(s):  
Claudio Roberto Duarte ◽  
Valéria V. Murata ◽  
Marcos A.S. Barrozo
Keyword(s):  
Control Volume ◽  
Flow Behavior ◽  
Cfd Modeling ◽  
Gas Flows ◽  
Present Calculation ◽  
Multiphase Model ◽  
Spouted Bed ◽  
Particle Coating ◽  
Spouted Beds ◽  
Good Agreement

Spouted bed systems have emerged as very efficient fluid-particle contactors and find many applications in the chemical and biochemical industry. Some important applications of spouted beds include coal combustion, biochemical reactions, drying of solids, drying of solutions and suspensions, granulation, blending, grinding, and particle coating. An extensive overview can be found in Mathur and Epstein[1]. The pattern of solid and gas flows in a spouted bed was numerically simulated using a CFD modeling technique. The Eulerian-Eulerian multifluid modeling approach was applied to predict gas-solid flow behavior. A commercially available, control-volume-based code FLUENT 6.1 was chosen to carry out the computer simulations. In order to reduce computational times and required system resources, the 2D axisymmetric segregated solver was chosen. The typical flow pattern of the spouted bed was obtained in the present calculation. The simulated velocity and voidage profiles presented a good agreement qualitative and quantitative with the experimental results obtained by He et al. [4].

scholarly journals Influence of inlet air distributor geometry on the fluid dynamics of conical spouted beds: A CFD study

2018 ◽  
Vol 24 (4) ◽  
pp. 369-378 ◽  
Author(s):  
J.N.M. Batista ◽  
R.C. Brito ◽  
R. Béttega
Keyword(s):  
Fluid Dynamics ◽  
Cfd Simulation ◽  
Low Cost ◽  
Scale Up ◽  
Straight Tube ◽  
Spouted Bed ◽  
Bed Height ◽  
Spouted Beds ◽  
Wide Range ◽  
Solid Dynamics

The spouted bed presents limitations in terms of scale-up. Furthermore, its stability depends on its geometry as well as the properties of the fluid and solid phases. CFD provides an important tool to improve understanding of these aspects, enabling a wide range of information to be obtained rapidly and at low cost. In this work, CFD simulation was used to evaluate the effects of different inlet air distributors (Venturi and straight tube) and the effects of static bed height on the fluid and solid dynamics of a conical spouted bed. Simulations were performed using the two-dimensional Euler-Euler approach. In order to evaluate the fluid dynamics model, static pressure data obtained by simulation were compared with experimental data obtained with the Venturi distributor. The fluid and solid dynamics of the conical spouted bed were obtained by CFD simulation. The results showed that the pressure drop was lower for the straight tube air distributor, while the Venturi air distributor provided higher stability and a more homogenous air distribution at the bed entrance.

Influence of Jordanian zeolite on the performance of a solar still: experiments and CFD simulation studies

2016 ◽  
Vol 16 (6) ◽  
pp. 1700-1709 ◽  
Author(s):  
Yazan Taamneh
Keyword(s):  
Experimental Data ◽  
Phase Change ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Solar Still ◽  
Cfd Simulations ◽  
Two Phase ◽  
Vof Model ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Computational fluid dynamics (CFD) simulations were performed for experiments carried out with two identical pyramid-shaped solar stills. One was filled with Jordanian zeolite-seawater and the second was filled with seawater only. This work is focused on CFD analysis validation with experimental data conducted using a model of phase change interaction (evaporation-condensation model) inside the solar still. A volume-of-fluid (VOF) model was used to simulate the inter phase change through evaporation-condensation between zeolite-water and water vapor inside the two solar stills. The effect of the volume fraction of the zeolite particles (0 ≤ ϕ ≤ 0.05) on the heat and distillate yield inside the solar still was investigated. Based on the CFD simulation results, the hourly quantity of freshwater showed a good agreement with the corresponding experimental data. The present study has established the utility of using the VOF two phase flow model to provide a reasonable solution to the complicated inter phase mass transfer in a solar still.

Numerical Simulation of Steady and Unsteady Compressible Multiphase Flows

2012 ◽  
Author(s):  
Huiying Li ◽  
Sergio A. Vasquez
Keyword(s):  
Experimental Data ◽  
Multiphase Flows ◽  
Volume Fraction ◽  
Numerical Approach ◽  
Absolute Pressure ◽  
Multiphase Model ◽  
Phase Volume ◽  
Phase Volume Fraction ◽  
Wide Range ◽  
Liquid Flows

The present work concerns the development of an advanced numerical approach to simulate steady and unsteady compressible multiphase flows in the CFD solver FLUENT. Compressible multiphase flows can be simulated under the framework of either the multiphase Mixture/VOF or the Eulerian multifluid model. The governing equations solved are the mixture (Mixture or VOF model) or phase (Eulerian multifluid model) momentum, energy, species transport equations and phase volume fraction equations. Turbulence effects are accounted for using a range of multiphase turbulence models. For the compressible multiphase model, it assumes that only one phase is a compressible gas/gaseous mixture with multiple species. In gas-liquid flows, all the liquid phases can be compressible /incompressible liquid, while in gas-solid flows the solid phase can be treated as a granular flow. To ensure numerical stability and obtain physical solutions, the absolute pressure is limited in a way to satisfy the constraints for both incompressible and compressible flows that may exist in different regions. The compressible effects are taken into account by adding extra terms related to sound speed and phase volume fractions in both the phase volume fraction and the pressure-correction equations. For flow conditions at inlets and exits, only pressure and mass-flow-rate boundaries are applicable. The mixture Mach numbers are defined and used to determine the subsonic or supersonic flows and thermal boundary conditions. The compressible multiphase model have been successfully used to simulate steady and unsteady, sub- and super-sonic compressible multiphase flows in a wide range of 2D and 3D multiphase systems. The examples presented in the paper include: (1). Gas-liquid separation in a vertical cylindrical container; (2). Transient pressure variations in compressible liquid and gas-liquid flows of water hammers; (3). Sub- and super-sonic gas-liquid two-phase flows in a nozzle; (4). Cavitating and ventilated super-cavitating flows; and (5). 3D gas-liquid flows in a three-stream injector. The solver robustness and convergence performance will be discussed. The solutions will be compared with available experimental data or numerical solutions. Emphasis will be focused on the solver performances on simulations of compressible multiphase flows. Overall, the results obtained from the present compressible multiphase model are in line with analytical/CFD solutions or available experimental data. The numerical approach is reasonably fast and robust, and suitable for practical compressible multiphase applications.

Experimental Study of Transient Hydrodynamics in a Spouted Bed of Polydisperse Particles

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Ling Bai ◽  
Weidong Shi ◽  
Ling Zhou ◽  
Lingjie Zhang ◽  
Wei Li ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Gas Velocity ◽  
Spouted Bed ◽  
Clear Trend ◽  
Spouted Beds ◽  
Superficial Gas Velocity ◽  
Different Diameters ◽  
Polydisperse Particles

In industrial processes such as chemical looping combustion, single-component spouted beds of monodisperse particles are very rarely used but the spouted beds of polydisperse particles have been widely used. The flow characteristics of polydisperse particles are much more complex than the single particle fraction in a fluidized bed. To investigate the gas–solid two-phase flow characteristics of the particles with different diameters in a spouted bed, the segregation and mixing characteristics, bubble morphology, minimum spouting velocity, and pressure fluctuations of the particles with different sizes under different superficial gas velocities are studied experimentally. The results show that higher the initial bed height and larger the volume fraction of the bigger particles, higher is the minimum spouting velocity. Moreover, the magnitude of the minimum spouting velocity increases exponentially with increase in the volume fraction of the bigger particles. At low superficial gas velocity, there is a clear trend of segregation between the particles of different diameters. At moderate superficial gas velocity, the mixing trend among particles of different diameters is enhanced, and the pressure fluctuations in the bed present some degree of regularity. At high superficial gas velocity, the particles of different diameters tend to separate again, the pressure fluctuations become intense, and the particle flow turns into a turbulent state. Furthermore, when the bed becomes stable, the particles of different diameters distribute within the bed with regular stratification.

Study of Measurement Methods of Particle Velocity in a Spouted Bed

2012 ◽  
Vol 727-728 ◽  
pp. 1842-1847
Author(s):  
D.A. Santos ◽  
G.C. Alves ◽  
M.A.S. Barrozo ◽  
Claudio Roberto Duarte
Keyword(s):  
Particle Velocity ◽  
High Speed ◽  
Measurement Techniques ◽  
Video Camera ◽  
Three Dimensions ◽  
Average Particle ◽  
Multiphase Model ◽  
Spouted Bed ◽  
Spouted Beds ◽  
Fiber Optical

Average particle velocity measurements were carried out in a conical-cylindrical spouted bed made of acrylic. In this study an intrusive fiber optical technique which is based on a cross-correlation function between signals from its two channels was used. For a non-intrusive measurement in order to compare with the intrusive technique, images of particle movement were recorded using a high-speed video camera. The experiments were conducted in differents air velocity conditions above the minimum spouting velocity. The latter method was limited in velocity measurement only near the spouted beds wall inasmuch as the spouted bed used was a three dimensions one. On the other hand, the fiber optical is a promising technique for measuring particle velocity distributions in a three dimensions spouted bed. To predict the minimum spouting velocity in order to use this result in the measurement techniques investigation, simulations were carried out using the Eulerian-Eulerian multiphase model.

Modeling a New Rotational Reciprocating Plate Impeller Using Computational Fluid Dynamics

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Yun Lin ◽  
Jules Thibault ◽  
Zisheng Zhang
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Liquid Velocity ◽  
Fermentation Broth ◽  
Velocity Shear ◽  
Multiphase Model ◽  
Rushton Turbine ◽  
Simulation Results

A new impeller, the rotational reciprocating plate impeller (RRPI), designed to handle highly viscous fermentation broth, was modeled using computational fluid dynamics (CFD) to gain more insight into its performance. A standard Rushton turbine was first simulated using CFD software Fluent(r) for validation purposes. Under experimental conditions, the prediction of the power number obtained from CFD simulation agrees qualitatively with the experimental data. Multiphase simulation was used to better represent the gas-liquid interactions using Eulerian multiphase model. The rotational reciprocating movement of the RRPI was approximated using small time steps, each of which has a different rotation speed. Water and carboxymethyl cellulose (CMC) solutions were used as model fluids to represent the different stages of a typical fermentation with a rheologically-evolving broth. By comparing the simulation results to experimental data, the efficiency of the toothed belt used to drive the Rushton turbine impeller was confirmed to be high as expected, while the efficiency of the three-arm linkage system used to achieve the rotational reciprocation of the RRPI was estimated to be around 80%. The uniformity of mixing with the 3-Rushton impeller and the RRPI was compared to each other by investigating the distribution of liquid velocity, shear rate, and broth viscosity. The simulation results proved that the RRPI eliminated the dead zones that usually form when the Rushton turbines are used in viscous medium.

Influence of Boundary Conditions on CFD Simulation of Gas- particle Hydrodynamics in a Conical Fluidized Bed Unit

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Alireza Bahramian ◽  
Mansour Kalbasi ◽  
Martin Olazar
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Fluidized Bed ◽  
Cfd Simulation ◽  
Tangential Velocity ◽  
Optical Probe ◽  
Multiphase Model ◽  
Numerical Predictions ◽  
Conical Fluidized Bed

The hydrodynamics of gas-particle conical fluidized bed containing dried TiO2 micro-size particles were studied experimentally and computationally. The pressure drop was studied by pressure measurements and mean solid velocity in the different axial and radial positions and their experimental values were measured by a parallel 3-fiber optical probe. The Eulerian-Eulerian multiphase model, including kinetic theory of granular flow using Gidaspow (1994) drag function was used in the computational fluid dynamics (CFD) simulation. The frictional viscosity of solids is predicted from the equation proposed by Schaeffer (1987), whereas semi-empirical boundary equations developed by Johnson and Jackson (1987) were applied for the tangential velocity and granular temperature of the solids at the wall. Three different types of boundary conditions (BC), consisting in free-slip/no-friction, no-slip/friction and high-slip/small-friction, were used in this work to compare the results of the model with the experimental data. The numerical predictions using free-slip/no-friction BC agreed reasonably well with the experimental pressure drop measurements, especially at superficial gas velocities higher than the minimum fluidization velocity, Umf. The results for simulated mean axial solid velocity show that the free-slip BC was in better agreement with the experimental data compared with the other boundary conditions. The model also provides reasonable predictions for particle circulation and formation of fountain zone, gulf-effect and air velocity.

CFD Multifluid Simulation of Spouted Beds with and without Internal Draft Tubes

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Mahmood Reza Rahimi ◽  
Salar Azizi
Keyword(s):  
Experimental Data ◽  
Particle Trajectory ◽  
Draft Tube ◽  
Granular Flows ◽  
Spouted Bed ◽  
Drag Model ◽  
Spouted Beds ◽  
Particulate Solids ◽  
Computational Fluid Dynamics Cfd ◽  
Draft Tubes

The insertion of an axially positioned non-porous and porous draft tube into the conventional spouted bed has shown potential advantages in stability and flexibility of the system and controlling particle trajectory history. In this work with computational fluid dynamics (CFD), important information on the flow field within three types of spouted bed has been provided and influences of using internal tube on spouted beds hydrodynamics were investigated. The simulation used the multi-fluid Eulerian-Eulerian approach based on kinetic theory of granular flows (KTGF), incorporating a kinetic-frictional constitutive model for dense assemblies of particulate solids and Gidaspow’s drag model for the interaction between gas and particles. Finally, the modeling results were compared with the experimental data from literature.

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