Comparison of Spherical and Non-Spherical Objects in Cyclonic and Uniaxial Flow Regimes

2018 ◽  
Vol 884 ◽  
pp. 93-104
Author(s):  
Thomas Archbold ◽  
James K. Carson
Keyword(s):  
Drag Coefficient ◽  
Separation Efficiency ◽  
Tangential Velocity ◽  
Orientation Angle ◽  
Particle Orientation ◽  
Cfd Simulations ◽  
Chestnut Shell ◽  
Pneumatic Separation ◽  
Vortex Finder ◽  
Shell Particles

This paper uses the Muschelknautz method to model the cyclone separation of chestnut shell and kernel fragments simulated as a square plate and sphere respectively. Because of the opposing geometry of the kernel and shell particles, a new framework is derived using CFD simulations to predict the drag coefficient of the shell particle as a function of orientation and Reynolds number. The drag coefficient of the shell is approximately proportional to the sine of the orientation angle, squared. Despite this, particle orientation remains relatively constant for all practical geometric and velocity parameters within a cyclone, as implied by the assumptions used in this paper. The results from the separation model show that the tangential velocity is almost 86 times greater than the radial velocity of the particle beneath the vortex finder. Consequently, the full frontal area of the particle is not exposed to the radial flow and the particles are not separated effectively by drag force. An experimental separation efficiency of 28.5% compared to an efficiency of 0% predicted by classical cyclone theory, indicates that the shell particles could be re-entrained at the base of the cyclone. This suggests that cyclones do not utilise the differences in drag between particles. The simulation of chestnut kernel and shell particles in a uniaxial flow field (such as occurs in pneumatic separation) shows that it is theoretically possible to achieve a significantly larger separation efficiency when compared to cyclones.

scholarly journals Study of GLR and Inlet Velocity on Hydrocyclone for Fracturing Flow-Back Fluids

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Bing Liu ◽  
Huajian Wang ◽  
Luncao Li ◽  
Zhenjiang Zhao ◽  
Liping Xu ◽  
...  
Keyword(s):  
Particle Size ◽  
Separation Efficiency ◽  
Tangential Velocity ◽  
Reynolds Stress Model ◽  
Optimum Range ◽  
Inlet Velocity ◽  
Split Ratio ◽  
Vortex Finder ◽  
Computational Fluid Dynamics Cfd ◽  
Solid Liquid

In this work, based on the Reynolds stress model (RSM) of the computational fluid dynamics (CFD) software Fluent and experimental method, the velocity field, pressure characteristics, split ratio, and separation efficiency of the hydrocyclone are analyzed under different gas-liquid ratios (GLRs). For the inlet velocity, the lower limit is ascertained by the flow field stability, the upper limit is largely determined by the energy consumption, and the optimum range is 4 m/s to 10 m/s. Within the optimum range, the peak value of tangential velocity increases while the GLR increases, whereas the pressure and pressure drop decrease. With the increase in the GLR, the axial velocity decreases, and the locus of zero vertical velocity shifts inward. The increase in the GLR causes more gas to collect at the vortex finder, which hinders the discharge of the solid-liquid mixture from the overflow, and the larger the GLR, the faster the decrease in the split ratio. The separation efficiency of particles with a particle size of 15 μm is increased by 6.75%, and the separation efficiency of particles with a particle size of 30 μm is increased by 0.57%. Meanwhile, the separation efficiency is increased by 2.43%, and the cut size d50 is reduced as the GLR increases.

scholarly journals Numerical investigation of the hydrocyclone vortex finder depth on separation efficiency

2021 ◽  
Vol 347 ◽  
pp. 00039
Author(s):  
Lesiba Mokonyama ◽  
Thokozani Justin Kunene ◽  
Lagouge Kwanda Tartibu
Keyword(s):  
Fluid Dynamics ◽  
Cfd Simulation ◽  
Fine Particles ◽  
Volume Fraction ◽  
Separation Efficiency ◽  
Cfd Simulations ◽  
Industrial Sectors ◽  
Air Core ◽  
Vortex Finder ◽  
Computational Fluid Dynamics Cfd

Hydrocyclones are devices used in numerous chemicals, food, and mineral-related industrial sectors for the separation of fine particles. A d50 mm hydrocyclone was modelled with the use of the Computational fluid dynamics (CFD) simulation, ANSYS® Fluent 2021 R1. The vortex finder depth was varied from 20 mm, 30 mm, and 35 mm to observe the effects of pressure drop and separation efficiency from a varied vortex finder depth and characteristics of the air core. The numerical methods validated the results observed from different parameters such as volume fraction characteristics based on CFD simulations. The tangential and axial velocities increased as the vortex finder length increased. It was found that as the depth of the vortex finder is increased, particle re-entrainment time in the underflow stream increases, and separation efficiency improved.

scholarly journals Design and Analysis of a Separator for Aluminium Dust Particle Collection

2021 ◽  
Vol 335 ◽  
pp. 03013
Author(s):  
Jia Hao Tan ◽  
Douglas Kum Tien Tong ◽  
Edwin Chin Yau Chung
Keyword(s):  
Separation Efficiency ◽  
Dust Sample ◽  
Solid Particles ◽  
Working Environment ◽  
Cfd Simulations ◽  
Particle Collection ◽  
Vortex Finder ◽  
Predicted Values ◽  
Do So

Cyclone separators are considered one of the most common and widely used method of separating solid particles from fluids. The focus of this paper was to design a separator that could effectively improve the air quality of an industrial working environment by considering factors such as the nature of the particles and the restrictions on the device such as size and operating condition. To do so, a sample of the dust sample was studied to determine the characteristics of the aluminum dust. An initial separator model which satisfied the separation condition was developed, and a second model was developed with the goal of optimizing and reducing the overall size of the separator. All models developed were subjected to CFD simulations to analyze the flow patterns, separation rate at various particle diameters as well as comparing against the theoretical predicted values. The simulation results showed how the change in various parameters improved the separation efficiency. The total height of the model was approximately 20% smaller than the initial proposed design to fit into the manufacturer’s workbench while the separation efficiencies improved by an average of 5% to 10% across various particle sizes. The results obtained indicated that the efficiency of the particle collection is dependent on the area of the barrel inlet of the separator and the depth of the vortex finder.

scholarly journals Influence of Vortex Finder Structure on Separation Performance of Double-Overflow Three-Product Hydrocyclones

Separations ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 79
Author(s):  
Yuekan Zhang ◽  
Jiangbo Ge ◽  
Lanyue Jiang ◽  
Hui Wang ◽  
Junru Yang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Experimental Research ◽  
Separation Efficiency ◽  
Structural Parameters ◽  
Separation Performance ◽  
Insertion Depth ◽  
Flow Field Characteristics ◽  
Vortex Finder ◽  
Fine Classification

In view of the difficulty of traditional hydrocyclones to meet the requirements of fine classification, a double-overflow three-product (internal overflow, external overflow and underflow) hydrocyclone was designed in this study. Numerical simulation and experimental research methods were used to investigate the effects of double-overflow flow field characteristics and structural parameters (i.e., internal vortex finder diameter and insertion depth) on separation performance. The research results showed that the larger the diameter of the internal vortex finder, the greater the overflow yield and the larger the cut size. The finest internal overflow product can be obtained when the internal vortex finder is 30 mm longer than the external vortex finder. The separation efficiency is highest when the internal vortex finder is 30 mm shorter than the external vortex finder.

Computational and Experimental Investigation of the Vertical Flash Tank Separator Part 1: Effect of Parameters on Separation Efficiency

2019 ◽  
Vol 27 (01) ◽  
pp. 1950005 ◽  
Author(s):  
Raid Ahmed Mahmood ◽  
David Buttsworth ◽  
Ray Malpress
Keyword(s):  
Separation Efficiency ◽  
Fluid Dynamic ◽  
Effective Area ◽  
Working Fluid ◽  
Cfd Simulations ◽  
Liquid Separation ◽  
Two Phase ◽  
Flash Tank ◽  
Tank Design ◽  
The Heat Transfer Coefficient

The flash tank separator is one of the most important components that can be used to improve the performance of a refrigeration cycle by separating the liquid from the gas–liquid two-phase flow and providing the evaporator with only liquid refrigerant. This technique increases the effective area and enhances the heat transfer coefficient in the evaporator. To optimize the size of the vertical flash tank separator for obtaining high separation efficiency, the effect of the size of the vertical flash tank separator needs to be considered. This paper investigates the effect of the size on the liquid separation efficiency of the vertical flash tank separator. This paper also assesses the usefulness of Computational Fluid Dynamic (CFD) in flash tank design, and this is achieved through experiments and simulations on a range of relevant configurations using water as the working fluid. The results revealed that the size has a significant effect on the liquid separation efficiency, as the highest value was achieved by the largest size (VFT-V5). The CFD simulations give a good agreement with the experiments; all the simulations underestimated the liquid separation efficiency by approximately 0.02 over the range of conditions tested.

Effect of particle orientation and of flow velocity on the combustibility of Pinus pinaster and Eucalyptus globulus firebrand material

2011 ◽  
Vol 20 (8) ◽  
pp. 946 ◽  
Author(s):  
Miguel Almeida ◽  
Domingos Xavier Viegas ◽  
Ana Isabel Miranda ◽  
Valeria Reva
Keyword(s):  
Flow Velocity ◽  
Eucalyptus Globulus ◽  
Pinus Pinaster ◽  
Orientation Angle ◽  
Fire Spread ◽  
Particle Orientation ◽  
Representative Species ◽  
Negative Effect ◽  
Experimental Laboratory ◽  
Pine Cones

Spotting is a very important mechanism of forest fire spread. Its negative effect increases in extreme fire danger conditions. In order to predict the maximum spotting distance, the duration of the combustion reaction of potential firebrands should be evaluated. This paper reports the results of an experimental laboratory study of the combustibility of firebrand material (pine cones and scales and pieces of bark of eucalypt) of two representative species in Portugal, Pinus pinaster Ait. and Eucalyptus globulus Labill. The main purpose was to assess the role on the burning conditions of the firebrand particle orientation angle θ in relation to the airflow and of the flow velocity (U) around the particle. Tests were made varying the angle of orientation of the main axis of the particle in relation to incident flow in the range of ±90°; flow velocities were tested from 0 to 6.5 m s–1. After ignition, particle mass loss owing to flaming or glowing combustion of the particle was continuously measured. Residual mass, duration of the flaming phase and the burnout times are reported for each case. Empirical models to estimate the trends of variation of some of these parameters with θ and U are proposed to illustrate their importance for the range of test conditions.

CFD Assessment and Experimental Investigation of the Liquid Separation Efficiency Enhancements in a Vertical Gravity Separator

2020 ◽  
Vol 28 (03) ◽  
pp. 2050021
Author(s):  
Raid Ahmed Mahmood
Keyword(s):  
Separation Efficiency ◽  
Flow Direction ◽  
Fluid Dynamic ◽  
Working Fluid ◽  
Cfd Simulations ◽  
Liquid Separation ◽  
Flash Tank ◽  
Tank Design ◽  
Vertical Gravity ◽  
Design Options

Three design enhancement options for a vertical gravitational flash tank separator were proposed and investigated in this work. Computational Fluid Dynamic (CFD) was used to assess the optimum configurations of the vertical gravitational flash tank separator. A series of experiments were performed to test the CFD proposed configurations of the enhancement design options. This paper also assessed the usefulness of CFD in flash tank design, and this is achieved through experiments and simulations on a range of relevant configurations using water as the working fluid. The results revealed that the combination of the inlet flow direction and extractor had a significant effect on the performance of the vertical flash tank separator which increased by 2%. The results also revealed that there was a good agreement between the CFD simulations and experiments; the CFD simulations underestimated the liquid separation efficiency by approximately 0.02 over the range of conditions tested.

Study on Characteristics and Operating Parameters of Axial Rotating Hydrocyclone

2009 ◽  
Author(s):  
Yan Xu ◽  
Zunce Wang ◽  
Fengxia Lv ◽  
Sen Li
Keyword(s):  
Pressure Drop ◽  
Laboratory Experiments ◽  
Separation Efficiency ◽  
Rotation Speed ◽  
Tangential Velocity ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Axial Rotation ◽  
Rotating Wall ◽  
Simulation Results

The axial rotation of the hydrocyclone affects its internal flow characteristics and separating effect directly, as some local applications require the static hydrocyclone rotates about its own axis. Based on CFD, velocity distribution in the axial rotating hydrocyclone is studied. It is shown that as the rotation speed increasing, the tangential velocity improves and its gradient reduces in free vortex region observably, while the radial velocity has an incremental trend in the section of the small cone. The laboratory experiments are carried out for the static hydrocyclone of disposal capacity of 4 m3/h at 100r/min ∼ 300r/min. The relationships among rotation speed, flowrate, pressure drop and separated efficiency are achieved, which agree well with the numerical simulation results. The results indicate that the disposal capacity of hydrocyclone subjected to the rotation wall can be more flexible than that with no-rotating wall, the scope of best disposal capacity gradually enlarges with the increase of rotation speed of wall. Appropriate rise of the rotation speed is favor of the separation efficiency at the steady flowrate, however the increase of the flowrate and rotation speed induces the growth of the hydrocyclone’s pressure drop correspondingly to some extent.

Study on the Configuration Effect of a Vortex Finder for a Gas-Solid Cyclone Separator Using Eulerian-Eulerian Approach

2013 ◽  
Author(s):  
Moonho Choi ◽  
Sungwon Lee ◽  
Jin-Ki Ham
Keyword(s):  
Pressure Loss ◽  
Erosion Rate ◽  
Separation Efficiency ◽  
Solid Particles ◽  
Least Square ◽  
Design Parameters ◽  
Reduced Pressure ◽  
Eulerian Approach ◽  
Method Of Least Square ◽  
Vortex Finder

Granular model, a part of Eulerian-Eulerian approach is implemented to improve a gas-solid cyclone separator’s performances which are largely determined by dimensions of a vortex finder. Design-Of-Experiments method analyzes the performances such as pressure loss, separation efficiency, and erosion rate of each variation model due to the change of design parameters of the vortex finder. Separation efficiencies due to the motion of solid particles are predicted according to the classical efficiency model by using the method of least square. The numerical results are validated by comparing with previously reported experimental data. The standard Stairmand design cyclone is improved judging from the reduced pressure loss by 43%, the reduced cut size by 63% and the reduced erosion rate by 2% by changing the position and the diameter of the vortex finder.

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