scholarly journals Improving the Homogenization of the Liquid-Solid Mixture Using a Tandem of Impellers in a Baffled Industrial Reactor

2021 ◽  
Vol 11 (12) ◽  
pp. 5492
Author(s):  
Adrian Stuparu ◽  
Romeo Susan-Resiga ◽  
Alin Bosioc
Keyword(s):  
Solid Particles ◽  
Bulk Liquid ◽  
Working Fluid ◽  
Multiphase Model ◽  
Tandem Configuration ◽  
Sliding Mesh ◽  
Solid Mixture ◽  
Stirred Reactor ◽  
Surface Liquid ◽  
Eulerian Multiphase Model

The paper explores a tandem configuration of three-blade impellers in a stirred reactor. The working fluid is a liquid-solid mixture and the stirring mechanism fitted with the two impellers must prevent the sedimentation of solid particles while homogenously dispersing them in the bulk liquid. The present numerical investigation, performed with the expert software Ansys® Fluent, Release 16, employs the Eulerian multiphase model along with the RNG k–ε turbulence model to simulate the free-surface liquid–solid flows in the baffled stirred reactor. A sliding mesh approach is used to model the impellers rotation. The tandem configuration is clearly superior to a single impeller, while the existing electrical motor that drives the stirring mechanism still provides the necessary power.

scholarly journals CFD Assessment of the Hydrodynamic Performance of Two Impellers for a Baffled Stirred Reactor

2021 ◽  
Vol 11 (11) ◽  
pp. 4949
Author(s):  
Adrian Stuparu ◽  
Romeo Susan-Resiga ◽  
Constantin Tanasa
Keyword(s):  
Phase Distribution ◽  
Solid Phase ◽  
Three Dimensional ◽  
Hydrodynamic Performance ◽  
Multiphase Model ◽  
Sliding Mesh ◽  
Solid Mixture ◽  
Stirred Reactor ◽  
Shaft Power

When converting a baffled stirred reactor to work with a different fluid, usually the original impeller must be replaced with a customized one. If the original impeller was designed for mixing liquids, its performance for liquid–solid suspensions may not be satisfactory. A case study is presented, where a two-blade original impeller is replaced with a new three-blade design. The new impeller shows clear improvements in mixing a liquid–solid suspension, while keeping the shaft power practically at the same level. As a result, a practically homogenous liquid–solid mixture is obtained, thus ensuring the required quality of the final product. The present numerical investigations employ the Eulerian multiphase model with renormalization (RNG) k–ε turbulence model to simulate the three-dimensional unsteady free-surface liquid–solid flow in a stirred tank. A sliding mesh approach was used to account for the impeller rotation within the expert code, FLUENT 16. The comparative quantitative analysis of the solid phase distribution and the relevant velocity profiles show that the new design of three-blade-impeller is significantly increasing the sedimentation time of the solid phase beyond the chemical reaction specific time. The necessary power to drive the new impeller has a slightly higher value than for the original impeller but it can be sustained by the existing driving system.

CFD Study the Influence of Solid Phase on the Pump Performance

2014 ◽  
Author(s):  
Mikhail P. Strongin
Keyword(s):  
Flow Rate ◽  
Volume Fraction ◽  
Solid Phase ◽  
Pure Water ◽  
Solid Particles ◽  
Spherical Particles ◽  
Multiphase Model ◽  
Solid Mixture ◽  
Water Transportation ◽  
Pump Head

In the water transportation applications of the liquid-solid mixture pumping is very common. Among these applications the submersible well pumps, dewatering, drainage, and irrigation could be mentioned. In this work, CFD study of influence of amount of solid phase in the solid-liquid mixture on the pump parameters is presented. Two stages vertical mixed flow pump was modeled. Fluent 14.5.7 commercial code was used for simulations. Mixer multiphase model can be used to model multiphase flows where the phases move at different velocities, but assume local equilibrium over short spatial length scales. Therefore, it was chosen for mixture model. SST k-ω model for turbulence was selected. Multi-reference frame approach was used for rotation domains. All mixtures in the presented work have water as their primary phase; the secondary phase is assumed to be a continuum of solid spherical particles of silicon with diameters that range from 0.1 mm to 0.4 mm. The load of the solid particles ranges from 0.5% to 10% of volume fraction of the mixture on the pump inlet. The total number of the mesh cells was 9 million. Calculations of the pump head for mixture and for pure water were done using the same water flow rate. Comparison of the results shows that they are close within ∼1% difference. It needs to be emphasized that the pump head is determined by the liquid phase. On the other hand, the efficiency of the pump with high solid phase load was much lower in comparison with the same flow rate of water for pure water case. These results may help in designing pumps for transporting liquid-solid mixture.

Penetration Dynamics of Solid Particles into Liquids High-Speed Experimental Results and Modelling

2005 ◽  
Vol 473-474 ◽  
pp. 429-434 ◽  
Author(s):  
Olga Verezub ◽  
György Kaptay ◽  
Tomiharu Matsushita ◽  
Kusuhiro Mukai
Keyword(s):  
Contact Angle ◽  
Particle Size ◽  
Aqueous Solutions ◽  
Particle Velocity ◽  
Weber Number ◽  
High Speed ◽  
Solid Particles ◽  
Bulk Liquid ◽  
Distilled Water ◽  
Critical Weber Number

Penetration of model solid particles (polymer, teflon, nylon, alumina) into transparent model liquids (distilled water and aqueous solutions of KI) were recorded by a high speed (500 frames per second) camera, while the particles were dropped from different heights vertically on the still surface of the liquids. In all cases a cavity has been found to form behind the solid particle, penetrating into the liquid. For each particle/liquid combination the critical dropping height has been measured, above which the particle was able to penetrate into the bulk liquid. Based on this, the critical impact particle velocity, and also the critical Weber number of penetration have been established. The critical Weber number of penetration was modelled as a function of the contact angle, particle size and the ratio of the density of solid particles to the density of the liquid.

scholarly journals Numerical simulation of gas-solid flow in an interconnected fluidized bed

2015 ◽  
Vol 19 (1) ◽  
pp. 317-328 ◽  
Author(s):  
Giuseppe Canneto ◽  
Cesare Freda ◽  
Giacobbe Braccio
Keyword(s):  
Numerical Simulation ◽  
Fluidized Bed ◽  
Experimental Tests ◽  
Solid Particles ◽  
Multiphase Model ◽  
Cold Model ◽  
Conservation Equations ◽  
Solid Flow

The gas-particles flow in an interconnected bubbling fluidized cold model is simulated using a commercial CFD package by Ansys. Conservation equations of mass and momentum are solved using the Eulerian granular multiphase model. Bubbles formation and their paths are analyzed to investigate the behaviour of the bed at different gas velocities. Experimental tests, carried out by the cold model, are compared with simulation runs to study the fluidization quality and to estimate the circulation of solid particles in the bed.

A Novel Turbulent Aggregation Device for Flue Gas

2014 ◽  
Vol 955-959 ◽  
pp. 2425-2429 ◽  
Author(s):  
Yun Fei Li ◽  
Jian Guo Yang ◽  
Yan Yan Wang ◽  
Xiao Guo Wang
Keyword(s):  
Size Distribution ◽  
Flue Gas ◽  
Large Scale ◽  
Balance Model ◽  
Small Scale ◽  
Multiphase Model ◽  
Specific Performance ◽  
Particles Size Distribution ◽  
Scale Turbulence ◽  
Eulerian Multiphase Model

The purpose of this study is to construct a turbulent aggregation device which has specific performance for fine particle aggregation in flue gas. The device consists of two cylindrical pipes and an array of vanes. The pipes extending fully and normal to the gas stream induce large scale turbulence in the form of vortices, while the vanes downstream a certain distance from the pipes induce small one. The process of turbulent aggregation was numerically simulated by coupling the Eulerian multiphase model and population balance model together with a proposed aggregation kernel function taking the size and inertia of particles into account, and based on data of particles’ size distribution measured from the flue of one power plant. The results show that the large scale turbulence generated by pipes favours the aggregation of smaller particles (smaller than 1μm) notably, while the small scale turbulence benefits the aggregation of bigger particles (larger than 1μm) notably and enhances the uniformity of particle size distribution among different particle groups.

scholarly journals Implicit Finite Difference Simulation of Prandtl-Eyring Nanofluid over a Flat Plate with Variable Thermal Conductivity: A Tiwari and Das Model

Mathematics ◽  
2021 ◽  
Vol 9 (24) ◽  
pp. 3153
Author(s):  
Nidal H. Abu-Hamdeh ◽  
Abdulmalik A. Aljinaidi ◽  
Mohamed A. Eltaher ◽  
Khalid H. Almitani ◽  
Khaled A. Alnefaie ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Finite Difference ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Variable Thermal Conductivity ◽  
Solid Particles ◽  
Engine Oil ◽  
Working Fluid ◽  
Implicit Finite Difference

The current article presents the entropy formation and heat transfer of the steady Prandtl-Eyring nanofluids (P-ENF). Heat transfer and flow of P-ENF are analyzed when nanofluid is passed to the hot and slippery surface. The study also investigates the effects of radiative heat flux, variable thermal conductivity, the material’s porosity, and the morphologies of nano-solid particles. Flow equations are defined utilizing partial differential equations (PDEs). Necessary transformations are employed to convert the formulae into ordinary differential equations. The implicit finite difference method (I-FDM) is used to find approximate solutions to ordinary differential equations. Two types of nano-solid particles, aluminium oxide (Al2O3) and copper (Cu), are examined using engine oil (EO) as working fluid. Graphical plots are used to depict the crucial outcomes regarding drag force, entropy measurement, temperature, Nusselt number, and flow. According to the study, there is a solid and aggressive increase in the heat transfer rate of P-ENF Cu-EO than Al2O3-EO. An increment in the size of nanoparticles resulted in enhancing the entropy of the model. The Prandtl-Eyring parameter and modified radiative flow show the same impact on the radiative field.

scholarly journals Experimental and computational evaluation of a gas-solid suspension density distribution under circulating fluidized bed conditions

2021 ◽  
Vol 2130 (1) ◽  
pp. 012025
Author(s):  
P Mirek
Keyword(s):  
Density Distribution ◽  
Combustion Chamber ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Multiphase Model ◽  
Thermal Loads ◽  
Bottom Part ◽  
Boiler Load ◽  
Suspension Density ◽  
Eulerian Multiphase Model

Abstract The paper presents the results of operational measurements of the suspension density distribution in the 966 MWth supercritical Circulating Fluidized Bed boiler. The tests were carried out for four different unit thermal loads, i.e. 40, 60, 80, and 100% MCR. The conducted operational measurements showed that the suspension density distribution of the particulate material in the combustion chamber of the CFB boiler has the form of an exponential curve with maximum values occurring in the bottom part of the furnace. On the basis of the operational data, an attempt was made to reflect the suspension density distribution in the combustion chamber of the boiler using the ANSYS CFD software. The calculations were carried out using the Eulerian multiphase model in an unsteady state condition. As revealed by the simulations, the Eulerian multiphase model allows for a quantitative representation of the suspension density distribution of the granular material only for the maximum boiler load. For other thermal loads, quantitative representation of experimental distributions of suspension density using the Eulerian method is possible except for the dense region.

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