Effect of Inter-Particle Interaction on Particle Deposition in a Cross-Flow Microfilter

2013 ◽  
Author(s):  
Talukder Z. Jubery ◽  
Shiv G. Kapoor ◽  
John E. Wentz
Keyword(s):  
Surface Properties ◽  
Particle Deposition ◽  
Particle Trajectory ◽  
Particle Interaction ◽  
Cross Flow ◽  
Pore Wall ◽  
Operating Conditions ◽  
Hard Sphere Model ◽  
Wall Surface ◽  
Membrane Pore

Recent studies show that inter-particle interaction can affect particle trajectories and particle deposition causing fouling in the microfilters used for metal working fluids (MWFs). Inter-particle interaction depends on various factors: particle geometry and surface properties, membrane pore geometry and surface properties, MWF’s properties and system operating conditions, etc. A mathematical model with a Langevin equation for particle trajectory and a hard sphere model for particle deposition has been used to study the effect of particle’s size, particle’s surface zeta potential, inter-particle distance, and shape of membrane pore wall surface on particle trajectory and its deposition on membrane pore wall. The study reveals that bigger particles have a lesser tendency to be deposited on membrane pore walls than smaller particles. The shape of the membrane pore wall surface can also affect the particle deposition behavior.

Effect of Interparticle Interaction on Particle Deposition in a Crossflow Microfilter

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Talukder Z. Jubery ◽  
Shiv G. Kapoor ◽  
John E. Wentz
Keyword(s):  
Surface Properties ◽  
Particle Deposition ◽  
Particle Trajectory ◽  
Interparticle Distance ◽  
Pore Wall ◽  
Operating Conditions ◽  
Interparticle Interaction ◽  
Hard Sphere Model ◽  
Membrane Pore ◽  
System Operating

Recent studies show that interparticle interaction can affect particle trajectories and particle deposition causing fouling in the microfilters used for metal working fluids (MWFs). Interparticle interaction depends on various factors: particle geometry and surface properties, membrane pore geometry and surface properties, MWF's properties and system operating conditions, etc. A mathematical model with a Langevin equation for particle trajectory and a hard-sphere model for particle deposition has been used to study the effect of particle's size, particle's surface zeta potential, interparticle distance, and shape of membrane pore wall surface on particle trajectory and its deposition on membrane pore wall. The study reveals the microlevel force phenomena behind bigger particles having a lesser tendency to be deposited on membrane pore walls than smaller particles. Deposition of particles on pore walls with asperities such as previously deposited particles is also examined and it is found that such cases can reduce repulsive electrostatic forces and lead to a higher probability of particle capture.

Experimental and Computational Studies of Particle Scavenge Flow in Direct Laser Metal Sintering

2019 ◽  
Author(s):  
Morgan Austin ◽  
Thao Tran-Le ◽  
Robert Kunz ◽  
Timothy Simpson ◽  
Rui Ni
Keyword(s):  
High Speed ◽  
Particle Deposition ◽  
Single Phase ◽  
Cross Flow ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Phase Measurements ◽  
Direct Laser ◽  
Flow Systems ◽  
Lift Off

Abstract Powder Bed Fusion (PBF) cross-flow systems are designed to flow gas across the build plane and entrain metallic powder particles that are ejected during the build, due to the thermal and attendant released kinetic energy of the laser melt process. It is important that these particles be removed from the build chamber so that they do not redeposit on the build surface, as this uncontrolled particle deposition can degrade the part quality. Optimal design of these sub-systems involves tailoring a cross-flow jet such that most of the ejected particles are entrained and removed from the build chamber, while the top layer of particles that are freshly spread on the build plate are not entrained. Accordingly, a combined experimental and CFD study has been executed with the goal of developing engineering design guidance for these cross-flow systems. The closed loop small footprint wind tunnel incorporates a 0.305 m × 0.305 m × 0.915 m test section, a variable height build plate upon which powder can be spread, a variable geometry inlet nozzle, and variable flow rate so that a variety of cross-flow configurations can be tested. Helium bubble particle tracking velocimetry (PTV) was used to characterize the single-phase flow at a number of these operating conditions / configurations. In addition, high speed videography was used to study particle liftoff and entrainment at these same conditions. Using these measurements and attendant CFD models, critical particle liftoff Shield numbers were obtained using CFD predictions of friction velocity. Specifically, close agreement between CFD and measurements were obtained, so that predicted Shields numbers, Sh, could be correlated with particle Reynolds number, Reτ. In this paper we present details of the experimental facility and test program, experimental results including uncertainty/error analysis for the PTV measurements, as well as the videography results for an aluminum alloy powder. The results of the CFD modeling are compared to the single phase measurements. Since very good agreement is observed, predicted wall-shear stress values are used to estimate Sh vs. Reτ at flow rates where incipient particle lift-off is observed experimentally.

Cake Formation in Cross-Flow Microfiltration Systems

1992 ◽  
Vol 25 (10) ◽  
pp. 149-162 ◽  
Author(s):  
V. L. Pillay ◽  
C. A. Buckley
Keyword(s):  
Cross Flow ◽  
Operating Conditions ◽  
Waste Waters ◽  
Domestic Waste ◽  
Time Curve ◽  
Good Correspondence ◽  
Operating Variables ◽  
Start Up ◽  
Turbulent Flow Regime ◽  
Cake Formation

Cross-flow microfiltration (CFMF) has potentially wide application in the processing of industrial and domestic waste waters. Optimum design and operation of CFMF systems necessitates a knowledge of the characteristic system behaviour, and an understanding of the mechanisms governing this behaviour. This paper is a contribution towards the elucidation and understanding of the behaviour of a woven fibre CFMF operated in the turbulent flow regime. The characteristic flux-time curve and effects of operating variables on flux are presented for a limestone suspension cross-flow filtered in a 25 mm woven fibre tube. The phenomena contributing to the shape of the flux-time curve are discussed. A model of the mechanisms governing cake growth and limit is presented. Predicted steady-state fluxes show a notably good correspondence with experimentally measured values. It is also found that the flux may not be uniquely defined by the operating conditions, but may also be a function of the operating path taken to reach the operating point. This is of significance in the start-up and operation of CFMF units.

Unsteady simulations of migration and deposition of fly-ash particles in the first-stage turbine of an aero-engine

2021 ◽  
pp. 1-21
Author(s):  
Z. Hao ◽  
X. Yang ◽  
Z. Feng
Keyword(s):  
Fly Ash ◽  
Film Cooling ◽  
Particle Deposition ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Velocity Model ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Aero Engine

Abstract Particulate deposits in aero-engine turbines change the profile of blades, increase the blade surface roughness and block internal cooling channels and film cooling holes, which generally leads to the degradation of aerodynamic and cooling performance. To reveal particle deposition effects in the turbine, unsteady simulations were performed by investigating the migration patterns and deposition characteristics of the particle contaminant in a one-stage, high-pressure turbine of an aero-engine. Two typical operating conditions of the aero-engine, i.e. high-temperature take-off and economic cruise, were discussed, and the effects of particle size on the migration and deposition of fly-ash particles were demonstrated. A critical velocity model was applied to predict particle deposition. Comparisons between the stator and rotor were made by presenting the concentration and trajectory of the particles and the resulting deposition patterns on the aerofoil surfaces. Results show that the migration and deposition of the particles in the stator passage is dominated by the flow characteristics of fluid and the property of particles. In the subsequential rotor passage, in addition to these factors, particles are also affected by the stator–rotor interaction and the interference between rotors. With higher inlet temperature and larger diameter of the particle, the quantity of deposits increases and the deposition is distributed mainly on the Pressure Side (PS) and the Leading Edge (LE) of the aerofoil.

scholarly journals Data-driven Modelling of Microfiltration Process with Embedded Static Mixer for Steepwater from Corn Starch Industry

2017 ◽  
Author(s):  
Laslo Šereš ◽  
Ljubica Dokić ◽  
Bojana Ikonić ◽  
Dragana Šoronja-Simović ◽  
Miljana Djordjević ◽  
...  
Keyword(s):  
Corn Starch ◽  
Desirability Function ◽  
Specific Energy Consumption ◽  
Cross Flow ◽  
Operating Conditions ◽  
Transmembrane Pressure ◽  
Static Mixer ◽  
Permeate Flux ◽  
Experimental Conditions ◽  
Starch Industry

Cross-flow microfiltration using ceramic tubular membrane was applied for treatment of steepwater from corn starch industry. Experiments are conducted according to the faced centered central composite design at three different transmembrane pressures (1, 2 and 3 bar) and cross-flow velocities (100, 150 and 200 L/h) with and without the usage of Kenics static mixer. For examination of the influence of the selected operating conditions at which usage of the static mixer is justified, a response surface methodology and desirability function approach were used. Obtained results showed improvement in the average permeate flux by using Kenics static mixer for 211 % to 269 % depending on experimental conditions when compared to the system without the static mixer. As a result of optimization, the best results considering flux improvement as well as reduction of specific energy consumption were obtained at low transmembrane pressure and lower feed cross-flow rates.

Turbulent fluid and particle interaction in the boundary layer for cross flow over a tube

1998 ◽  
Vol 24 (2) ◽  
pp. 213-223 ◽  
Author(s):  
J.R. Fan ◽  
X.Y. Zhang ◽  
J. Jin ◽  
Y.Q. Zheng ◽  
K.F. Cen
Keyword(s):  
Boundary Layer ◽  
Particle Interaction ◽  
Cross Flow ◽  
Turbulent Fluid

Macro- and Microscale Fabrication by Field Assisted Nanoparticle Assembly - The Challenging Path from Science to Engineering

2012 ◽  
Vol 507 ◽  
pp. 155-162 ◽  
Author(s):  
G. Falk
Keyword(s):  
Particle Deposition ◽  
Membrane Surface ◽  
Debye Length ◽  
Alumina Nanoparticles ◽  
Navier Stokes ◽  
Particle Tracing ◽  
Membrane Pore ◽  
Stagnation Points ◽  
Electroosmotic Pumping ◽  
Exchange Membrane

Local electrophoretic deposition of alumina nanoparticles under external DC electric field conditions with submerged impinging jet type capillaries arranged at ion exchange membrane substrates is presented. In order to evaluate particle deposition mechanisms a mathematical model is derived describing electroosmotic pumping of electrolyte through a micrometre scaled channel. The system is governed by surficial charge discontinuities and modeled by coupled mass balances, Ohmic law, Navier Stokes, and Nernst-Planck equations. Based on the boundary conditions of bulk convective electrodiffusion the effect of the imposed surface potential on the fluid flow behaviour and on particle tracing characteristics is studied by means of numerical analysis. The following findings have been obtained. At the corner edges of the charged surficial boundaries micro-vortices are generated to build up local stagnation points onto the modeled membrane surface. Particle tracing analysis reveal that the particle movement is caused by mass transport within the membrane directed velocity field to the stagnation point. The complex electrokinetics and electrohydro-dynamics suggest further investigations at membrane pore sizes in the range of the Debye-length to model the non-linear current-voltage characteristic that has already been experimentally proven for these kind of membrane EPD systems.

scholarly journals Full Surface Heat Transfer Characteristics of Stator Ventilation Duct of a Turbine Generator

2020 ◽  
Author(s):  
Shinyoung Jeon ◽  
Changmin Son ◽  
Jangsik Yang
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Cross Flow ◽  
Surface Heat ◽  
Operating Conditions ◽  
Scale Model ◽  
Turbine Generator ◽  
Surface Heat Transfer ◽  
Ventilation Duct ◽  
Flow Case

Turbine generator operates with complex cooling system due to the challenge in controlling the peak temperature of the stator bar caused by ohm loss, which is unavoidable. Therefore, it is important to characterise and quantifies the thermal performance of the cooling system. The focus of the present research is to investigate the heat transfer and pressure loss characteristics of typical cooling system, so-called stator ventilation duct. A real scale model was built at its operating conditions for the present study. The direction of cooling air is varied to consider its operation condition, so that there are (1) outward flow and (2) inward flow cases. In addition, the effect of (3) cross flow (inward with cross flow case) is also studied. The transient heat transfer method using thermochromic liquid crystals is implemented to measure full surface heat transfer distribution. A series of Computational Fluid Dynamics analysis is also conducted to support the observation from the experiment. For the inward flow case, the results suggest that the average Nusselt number of the 2nd duct is about 30% higher than the 3rd duct. The trend is similar with the effect of cross flow. The CFD results are in good agreement with the experimental data.

scholarly journals Experimental Study for Counter to Cross Flow Air-cooled Heat Exchangerof Annular Tube having Internal Circular grooving at Different pitches - A Review

2020 ◽  
pp. 268-274
Author(s):  
Suneel Nagar ◽  
Ajay Singh ◽  
Deepak Patel
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Operating Conditions ◽  
Theory And Practice ◽  
Thermal Flow ◽  
Total Cost ◽  
Literature Theory ◽  
Modern Analytical ◽  
Annular Tube

The objective of this study is to provide modern analytical and empirical tools for evaluation of the thermal-flow performance or design of air-cooled heat exchangers (ACHE) and cooling towers. This review consist various factors which effect the performance of ACHE. We introduced systematically to the literature, theory, and practice relevant to the performance evaluation and design of industrial cooling. Its provide better understanding of the performance characteristics of a heat exchanger, effectiveness can be improved in different operating conditions .The total cost of cycle can be reduced by increasing the effectiveness of heat exchanger.

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