Study of the Transitional Flow and Particle Separation With a Fishhook Effect in a Mini-Hydrocyclone

The mini-hydrocyclone is being proposed as a micro-separator in complex micro-devices for in-line fine particle separation as it has a concise geometry and no moving parts,. In this work, we present a numerical study combined by experiments on a 5 mm minihydrocyclone to investigate the transitional flow and particle separation with the presence of a fishhook effect. The results showed that the simulation from the LES model gave good agreement with that from DNS at an inlet velocity of 0.4 m/s. The LES model was then used to study the higher inlet velocity cases of 1.0 and 1.8 m/s. The particle separation was predicted by a Lagrangian model with an added user defined function (UDF) in the Fluent code to account for the particle interaction. The modeling results for the three inlet velocities studied showed that small particle Reynolds number, ReP, resulted in a poorly developed wake behind the large particles, which did not entrain fine particles leading to a barely noticeable fishhook effect for the 0.4 m/s inlet velocity. In contrast, a large ReP gives rise to larger wakes, which are capable of entraining fine particles more efficiently causing the pronounced fishhook effect at higher inlet velocities. The results show the particle separation with the fishhook effect could be modeled based on the particle entrainment model, whereas the accurate simulation of the fishhook effect in future should include a correction coefficient that varies with Rep to improve the separation efficiency predictions.

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Cyclic Flow Experiments of a Fine Particle Separation Hydrocyclone

Volume 4: Materials Technology; Ocean Engineering ◽

10.1115/omae2007-29026 ◽

2007 ◽

Author(s):

Lixin Zhao ◽

Minghu Jiang

Keyword(s):

Flow Condition ◽

Fine Particle ◽

Fine Particles ◽

Separation Efficiency ◽

Amplitude Ratio ◽

Particle Separation ◽

Separation Performance ◽

Period Ratio ◽

Cyclic Flow ◽

Signal Type

Basic separating principle of hydrocyclones and the cyclic experimental research facilities are introduced. The difficulty of separating fine particle is described. Based on a solid-liquid hydrocyclone used for separating fine particles, effect of cyclic flow condition on hydrocyclone’s performance is studied. Effects of cyclic period ratio, cyclic flowrate amplitude ratio, Reynolds number, gas liquid ratio, and the cyclical signal type on the hydrocyclone’s fine particle separation performance, especially on relative overflow purifying rate were studied in detail. The results show that the separation efficiency of the hydrocyclone operated under cyclic flow condition can be higher than that in steady condition, when the cyclic period ratio is about 0.68 and the cyclic flowrate amplitude ratio is about 2%. Rectangular wave seems to be the best cyclic signal for enhancing the hydrocyclone’s separation efficiency. The cyclical change of flowrate leads to the increasing of hydrocyclone’s energy consumption to some extent, while the increasing amount is very less, which is no more than 3% in general.

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Study of the Particle Separation Performance of a Dust-settling Hopper

Chemical Product and Process Modeling ◽

10.2202/1934-2659.1589 ◽

2011 ◽

Vol 6 (1) ◽

Cited By ~ 4

Author(s):

Bofu Wu ◽

Jinlai Men ◽

Jie Chen

Keyword(s):

Fluid Dynamics ◽

Particle Concentration ◽

Separation Efficiency ◽

Simulation Analysis ◽

Numerical Study ◽

Particle Separation ◽

Separation Performance ◽

Particle Removal ◽

Airflow Velocity ◽

Calculation Results

This paper presents a numerical study to predict the particle separation performance of a dust-settling hopper using computational fluid dynamics. The Euler-Lagrange approach was employed to analyze the particle separation efficiency and the outflow particle concentration of the dust-settling hopper under different inlet airflow velocities. The calculation results obtained reveal that the overall particle separation efficiency and the outflow particle concentration decrease with the increase of the inlet airflow velocity, and the particle grade efficiency increases with particle size. Since there is a paradox between the particle separation performance and the particle removal performance for a street vacuum sweeper, it is necessary to counter-balance the effects of the inlet airflow velocity on them. According to the simulation analysis, an appropriate inlet airflow velocity is provided for the design of the dust-settling hopper.

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Numerical Study toward Optimization of Spray Drying in a Novel Radial Multizone Dryer

Energies ◽

10.3390/en14051233 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1233

Author(s):

Umair Jamil Ur Rahman ◽

Artur Krzysztof Pozarlik ◽

Thomas Tourneur ◽

Axel de Broqueville ◽

Juray De Wilde ◽

...

Keyword(s):

Spray Drying ◽

Droplet Size ◽

Separation Efficiency ◽

Numerical Study ◽

Three Dimensional ◽

Droplet Size Distribution ◽

Vortex Chamber ◽

Temperature Pattern ◽

Multiphase Model ◽

Drying Technology

In this paper, an intensified spray-drying process in a novel Radial Multizone Dryer (RMD) is analyzed by means of CFD. A three-dimensional Eulerian–Lagrangian multiphase model is applied to investigate the effect of solids outlet location, relative hot/cold airflow ratio, and droplet size on heat and mass transfer characteristics, G-acceleration, residence time, and separation efficiency of the product. The results indicate that the temperature pattern in the dryer is dependent on the solids outlet location. A stable, symmetric spray behavior with maximum evaporation in the hot zone is observed when the solids outlet is placed at the periphery of the vortex chamber. The maximum product separation efficiency (85 wt %) is obtained by applying high G-acceleration (at relative hot/cold ratio of 0.75) and narrow droplet size distribution (45–70 µm). The separation of different sized particles with distinct drying times is also observed. Smaller particles (<32 µm) leave the reactor via the gas outlet, while the majority of big particles leave it via the solids outlet, thus depicting in situ particle separation. The results revealed the feasibility and benefits of a multizone drying operation and that the RMD can be an attractive solution for spray drying technology.

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A numerical study on combined baffles quick-separation device

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2021-0007 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ehsan Dehdarinejad ◽

Morteza Bayareh ◽

Mahmud Ashrafizaadeh

Keyword(s):

Turbulent Flows ◽

Separation Efficiency ◽

Numerical Study ◽

Turbulence Models ◽

Complete Separation ◽

Solid Particles ◽

Flow Rates ◽

Separation Device ◽

Coupling Technique ◽

Laminar And Turbulent Flows

Abstract The transfer of particles in laminar and turbulent flows has many applications in combustion systems, biological, environmental, nanotechnology. In the present study, a Combined Baffles Quick-Separation Device (CBQSD) is simulated numerically using the Eulerian-Lagrangian method and different turbulence models of RNG k-ε, k-ω, and RSM for 1–140 μm particles. A two-way coupling technique is employed to solve the particles’ flow. The effect of inlet flow velocity, the diameter of the splitter plane, and solid particles’ flow rate on the separation efficiency of the device is examined. The results demonstrate that the RSM turbulence model provides more appropriate results compared to RNG k-ε and k-ω models. Four thousand two hundred particles with the size distribution of 1–140 µm enter the device and 3820 particles are trapped and 380 particles leave the device. The efficiency for particles with a diameter greater than 28 µm is 100%. The complete separation of 22–28 μm particles occurs for flow rates of 10–23.5 g/s, respectively. The results reveal that the separation efficiency increases by increasing the inlet velocity, the device diameter, and the diameter of the particles.

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Numerical Study on the Erosion Characteristics of U-Type Bend for Gas Solid Flow

Volume 2: I&C, Digital Controls, and Influence of Human Factors; Plant Construction Issues and Supply Chain Management; Plant Operations, Maintenance, Aging Management, Reliability and Performance; Renewable Energy Systems: Solar, Wind, Hydro and Geothermal; Risk Management, Safety and Cyber Security; Steam Turbine-Generators, Electric Generators, Transformers, Switchgear, and Electric BOP and Auxiliaries; Student Competition; Thermal Hydraulics and Computational Fluid Dynamics ◽

10.1115/power-icope2017-3412 ◽

2017 ◽

Cited By ~ 1

Author(s):

Yu Wang ◽

Qi He ◽

Ming Liu ◽

Weixiong Chen ◽

Junjie Yan

Keyword(s):

Particle Size ◽

Erosion Rate ◽

Loading Rate ◽

Pipe Wall ◽

Numerical Study ◽

Pulverized Coal ◽

Mass Loading ◽

Two Phase ◽

Inlet Velocity ◽

Pipe System

In pulverized coal-fired plant, the U-type bend is commonly used in flue gas and pulverized coal pipe system to due to the constraints of outer space. And gas-solid two-phase flow exists in these pipelines. The erosion of the pipe has significant effect on the safety and reliability of pipelines. In present paper, the erosion characteristics of U-type bend were investigated through CFD (Computational Fluid Dynamics) method. The wear distribution on the pipe wall was obtained. And the particle flow characteristics in U-type bend were analyzed. The influence of inlet velocity, mass loading rate and particle size on the erosion rate was studied as well. Result suggested that the maximum erosion rate increases exponentially with the increase of inlet velocity. And maximum erosion rate increases linearly with the increasing mass loading rate. Increasing particle size can aggravate the wear on the pipe wall.

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Numerical Study of Methane and Air Combustion Inside Heat-Recirculating Combustors

Volume 1: Fuels and Combustion, Material Handling, Emissions; Steam Generators; Heat Exchangers and Cooling Systems; Turbines, Generators and Auxiliaries; Plant Operations and Maintenance ◽

10.1115/power2013-98257 ◽

2013 ◽

Author(s):

Yanxia Li ◽

Zhongliang Liu ◽

Yan Wang ◽

Jiaming Liu

Keyword(s):

Gas Flow ◽

Numerical Study ◽

Convection Heat Transfer ◽

Central Area ◽

Small Scale ◽

Inlet Velocity ◽

Strong Convection ◽

Simulation Results ◽

Lean Fuel ◽

Set Up

A numerical model on methane/air combustion inside a small Swiss-roll combustor was set up to investigate the flame position of small-scale combustion. The simulation results show that the combustion flame could be maintained in the central area of the combustor only when the speed and equivalence ratio are all within a narrow and specific range. For high inlet velocity, the combustion could be sustained stably even with a very lean fuel and the flame always stayed at the first corner of reactant channel because of the strong convection heat transfer and preheating. For low inlet velocity, small amounts of fuel could combust stably in the central area of the combustor, because heat was appropriately transferred from the gas to the inlet mixture. Whereas, for the low premixed gas flow, only in certain conditions (Φ = 0.8 ～ 1.2 when ν0 = 1.0m/s, Φ = 1.0 when ν0 = 0.5m/s) the small-scale combustion could be maintained.

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