The Impact of Surface Forces on Particle Flow and Membrane Fouling in the Microfiltration of Metalworking Fluids

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Seounghyun Ham ◽  
Shiv G. Kapoor ◽  
Richard E. DeVor ◽  
John Wentz
Keyword(s):  
Brownian Motion ◽  
Surface Potential ◽  
Membrane Fouling ◽  
Fluid Dynamic ◽  
Fluid Velocity ◽  
Particle Surface ◽  
Metalworking Fluids ◽  
Partial Blocking ◽  
Repulsive Forces ◽  
The Impact

Microfiltration is an in-process recycling method that shows great potential to extend fluid life and reduce bacterial concentrations in synthetic and semisynthetic metalworking fluids. The primary problem facing the use of microfiltration is membrane fouling, which is the blocking of membrane pores causing reduced flux. In this paper a fluid dynamic model of partial and complete blocking in sintered alumina membranes is developed that includes hydrodynamic, electrostatic, and Brownian forces. Model simulations are employed to study the impact of electrostatic and Brownian motion forces on the progression of partial blocking. The simulations also examine the effects of fluid velocity, particle size, and particle surface potential. The inclusion of electrostatic and Brownian forces is shown to significantly impact the progression of the partial blocking mechanism. The addition of a strong interparticle electrostatic force is shown to eliminate the partial blocking build-up of small particles due to the presence of the repulsive forces between the particles. As a result, the time to complete blocking of the test pore was lengthened, suggesting that flux decline is reduced in the presence of electrostatic forces. The Brownian motion is shown to have a large impact at low fluid velocities. The most effective parameter set is a low fluid velocity, small particle sizes, high microemulsion surface potential, and high membrane surface potential.

The Impact of Surface Forces on Particle Flow and Pore Blocking in the Microfiltration of Metalworking Fluids

2009 ◽  
Author(s):  
Seounghyun Ham ◽  
John E. Wentz ◽  
Shiv G. Kapoor ◽  
Richard E. DeVor
Keyword(s):  
Brownian Motion ◽  
Surface Potential ◽  
Membrane Fouling ◽  
Fluid Dynamic ◽  
Fluid Velocity ◽  
Particle Surface ◽  
Metalworking Fluids ◽  
Partial Blocking ◽  
Repulsive Forces ◽  
The Impact

Microfiltration is an in-process recycling method that shows great potential to extend fluid life and reduce bacterial concentrations in synthetic and semi-synthetic metalworking fluids (MWFs). The primary problem facing this use of microfiltration is membrane fouling, which is the blocking of membrane pores causing reduced flux. In this paper a fluid dynamic model of partial and complete blocking in sintered alumina membranes is developed that includes hydrodynamic, electrostatic, and Brownian forces. Model simulations are employed to study the impact of electrostatic and Brownian motion forces on the progression of partial blocking. The simulations also examine the effects of fluid velocity, particle size, and particle surface potential. The inclusion of electrostatic and Brownian forces is shown to significantly impact the progression of the partial blocking mechanism. The addition of a strong inter-particle electrostatic force is shown to eliminate the partial blocking build-up of small particles due to the presence of the repulsive forces between the particles. As a result, the time to complete blocking of the test pore was lengthened, suggesting that flux decline is reduced in the presence of electrostatic forces. Brownian motion is shown to have a large impact at low fluid velocities. The most effective parameter set is a low fluid velocity, small particle sizes, high microemulsion surface potential, and high membrane surface potential.

Dynamic Simulations of Alumina Membrane Fouling From Recycling of Semisynthetic Metalworking Fluids

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
John E. Wentz ◽  
Shiv G. Kapoor ◽  
Richard E. DeVor ◽  
N. Rajagopalan
Keyword(s):  
Membrane Fouling ◽  
Fluid Dynamic ◽  
Cross Flow ◽  
Metalworking Fluids ◽  
Alumina Membrane ◽  
Dynamic Simulations ◽  
Membrane Pores ◽  
Alumina Membranes ◽  
Membrane Flux ◽  
Partial Blocking

The recycling of semisynthetic metalworking fluids (MWFs) using alumina membranes is significantly impacted by aggregated MWF microemulsions that cause partial and complete blocking of membrane pores. In this paper, computational fluid dynamic methods are employed to model both a portion of a sintered alumina membrane with tortuous pores and the microemulsions passing through it. Several particle size distributions, measured experimentally at various times through the membrane service life and under two different cross-flow velocities, were used to determine the particle sizes simulated in the flow. Simulated MWF particles smaller than the largest pore diameter were found to completely block the pore through the build-up of a network of particles that blocked smaller diameter inlets and outlets. The results demonstrate as well that significant membrane flux reduction can occur by partial blocking of pore inlets and outlets even in the absence of complete blocking.

Fouling on a Multistage Axial Compressor in the Presence of a Third Substance at the Particle/Surface Interface

2018 ◽  
Author(s):  
Nicola Aldi ◽  
Nicola Casari ◽  
Devid Dainese ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
...  
Keyword(s):  
Impact Velocity ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Fluid Dynamic ◽  
Particle Surface ◽  
Axial Compressor ◽  
Micro Particles ◽  
Multistage Compressor ◽  
Particle Ingestion ◽  
The Impact

Solid particle ingestion is one of the principal degradation mechanisms in the compressor and turbine sections of gas turbines. In particular, in industrial applications, the micro-particles not captured by the air filtration system can cause deposits on blades and, consequently, can result in a decrease in compressor performance. It is of great interest to the industry to determine which zones of the compressor blades are impacted by these small particles. However, this information often refers to single stage analysis. This paper presents three-dimensional numerical simulations of the micro-particle ingestion (0.15 μm – 1.50 μm) in a multistage (i.e. eight stage) subsonic axial compressor, carried out by means of a commercial CFD code. Particle trajectory simulations use a stochastic Lagrangian tracking method that solves the equations of motion separately from the continuous phase. The effects of humidity, or more generally, the effects of a third substance at the particle/surface interface (which is considered one of the major promoters of fouling) is then studied. The behavior of wet and oiled particles, in addition to the usual dry particles, is taken into consideration. In the dry case, the particle deposition is established only by using the sticking probability. This quantity links the kinematic characteristics of particle impact on the blade with the fouling phenomenon. In the other two cases, the effect of the presence of a third substance at the particle/surface interface is considered by means of an energy-based model. Moreover, the influence of the tangential impact velocity on particle deposition is analyzed. Introducing the effect of a third substance, such as humidity or oil, the phenomenon of fouling concerns the same areas of the multistage compressor. The most significant results are obtained by combining the effect of the third substance with the effect of the tangential component of the impact velocity of the particles. The deposition trends obtained with these conditions are comparable with those reported in literature, highlighting how the deposits are mainly concentrated in the early stages of a multistage compressor. Particular fluid dynamic phenomena, such as corner separations and clearance vortices, strongly influence the location of particle deposits.

scholarly journals Heat Transfer Analysis of 3-D Viscoelastic Nanofluid Flow Over a Convectively Heated Porous Riga Plate with Cattaneo-Christov Double Flux

2021 ◽  
Vol 9 ◽  
Author(s):  
K. Loganathan ◽  
Nazek Alessa ◽  
Safak Kayikci
Keyword(s):  
Brownian Motion ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Heat Transfer Analysis ◽  
Fluid Temperature ◽  
Heat Absorption ◽  
Nanoparticle Volume Fraction ◽  
Riga Plate ◽  
Viscoelastic Nanofluid ◽  
The Impact

The impact of heat-absorbing viscoelastic nanofluidic flow along with a convectively heated porous Riga plate with Cattaneo-Christov double flux was analytically investigated. The Buongiorno model nanofluid was implemented with the diversity of Brownian motion and thermophoresis. Making use of the transformations; the PDE systems are altered into an ODE system. We use the homotopy analysis method to solve these systems analytically. The reaction of the apposite parameters on fluid velocity, fluid temperature, nanoparticle volume fraction skin friction coefficients (SFC), local Nusselt number and local Sherwood number are shown with vividly explicit details. It is found that the fluid velocities reflect a declining nature for the development of viscoelastic and porosity parameters. The liquid heat becomes rich when escalating the radiation parameter. In addition, the nanoparticle volume fraction displays a declining nature towards the higher amount of thermophoresis parameter, whereas the inverse trend was obtained for the Brownian motion parameter. We also found that the fluid temperature is increased in viscoelastic nanofluid compared to the viscous nanofluid. When we change the fluid nature from heat absorption to heat generation, the liquid temperature also rises. In addition, the fluid heat is suppressed when we change the flow medium from a stationary plate to a Riga plate for heat absorption/generation cases.

scholarly journals Gyrotactic microorganism and bio-convection during flow of Prandtl-Eyring nanomaterial

2021 ◽  
Vol 10 (1) ◽  
pp. 201-212
Author(s):  
Tasawar Hayat ◽  
Inayat Ullah ◽  
Khursheed Muhammad ◽  
Ahmed Alsaedi
Keyword(s):  
Brownian Motion ◽  
Fluid Velocity ◽  
Convergent Series ◽  
Entropy Generation Rate ◽  
Surface Drag ◽  
Concentration Difference ◽  
Brownian Motion And Thermophoresis ◽  
Buongiorno Model ◽  
Gyrotactic Microorganism ◽  
The Impact

Abstract Our main intension behind this work is to investigate Prandtl-Eyring nanomaterial in presence of gyrotactic microorganisms. Flow is generated via stretching sheet and is subject to melting heat effect. Radiation and dissipation are addressed. Entropy rate is also reported. Nanofluid effects are explored through Buongiorno model for nanofluid by considering Brownian motion and thermophoresis impacts. Problem related modelling is done by obtaining PDEs and these PDEs are then transmitted into ODEs by using appropriate similarity variables. Homotopic technique has been employed to obtain a convergent series solution of the considered problem. Graphical results have been presented to investigate the impact of different prominent variables over fluid velocity, temperature distribution, nanofluid concentration and on microorganism concentration. Entropy analysis has been discussed and the physical quantities such as surface drag force, Nusselt number, local Sherwood number and microorganism density number for the current problem is obtained. Velocity boost against higher melting and fluid parameters. Temperature of the fluid reduces with an increment in melting and radiation parameters while it intensifies through Prandtl and Eckert number, Brownian motion and thermophoresis parameters. Decay in concentration is noticed against higher values of melting and thermophoresis parameters while it increases for higher Schmidt number and Brownian motion parameter. Microorganism field boosts with higher values of Peclet number and microorganism concentration difference parameter. Moreover entropy generation rate intensifies against higher radiation parameter and Brickman number.

An Analytical Modeling and Performance Analysis of Graded Work Function Gate Recessed Channel SOI-MOSFET

2019 ◽  
Vol 9 (4) ◽  
pp. 504-511
Author(s):  
Sikha Mishra ◽  
Urmila Bhanja ◽  
Guru Prasad Mishra
Keyword(s):  
Analytical Model ◽  
Surface Potential ◽  
Threshold Voltage ◽  
Silicon On Insulator ◽  
Junction Depth ◽  
Short Channel ◽  
Soi Mosfet ◽  
Minimum Surface ◽  
Recessed Channel ◽  
The Impact

Introduction: A new analytical model is designed for Workfunction Modulated Rectangular Recessed Channel-Silicon On Insulator (WMRRC-SOI) MOSFET that considers the concept of groove gate and implements an idea of workfunction engineering. Methods: The impact of Negative Junction Depth (NJD) and oxide thickness (tox) are analyzed on device performances such as Sub-threshold Slope (SS), Drain Induced Barrier Lowering (DIBL) and threshold voltage. Results: The results of the proposed work are evaluated with the Rectangular Recessed Channel-Silicon On Insulator (RRC-SOI) MOSFET keeping the metal workfunction constant throughout the gate region. Furthermore, an analytical model is developed using 2D Poisson’s equation and threshold voltage is estimated in terms of minimum surface potential. Conclusion: In this work, the impact of Negative Junction Depth (NJD) on minimum surface potential and the drain current are also evaluated. It is observed from the analysis that the analog switching performance of WMRRC-SOI MOSFET surpasses RRC-SOI MOSFET in terms of better driving capability, high Ion/Ioff ratio, minimized Short Channel Effects (SCEs) and hot carrier immunity. Results are simulated using 2D Sentaurus TCAD simulator for validation of the proposed structure.

Thermal analysis of higher-order chemical reactive viscoelastic nanofluids flow in porous media via stretching surface

2021 ◽  
pp. 095440622110084
Author(s):  
Mohamed R Eid ◽  
F Mabood
Keyword(s):  
Brownian Motion ◽  
Transfer Rate ◽  
Fluid Velocity ◽  
Mass Transfer Rate ◽  
Higher Order ◽  
Flow In Porous Media ◽  
Viscoelastic Parameter ◽  
Suction Parameter ◽  
And Brownian Motion ◽  
Magnetic Strength

The essence of the present investigation is to reveal the hydrothermal variations of viscoelastic nanofluid flow in a porous medium over a stretchable surface. A higher-order chemical reaction is incorporated with thermophoresis and Brownian motion. Similarity conversions reduce the resulting equations into their dimensionless form and then solved using Runge-Kutta-Fehlberg (RKF) based shooting procedure. The effects of underlying factors on the flow are discussed through various graphs and tables. Computational results for noteworthy skin friction and heat and mass transport are presented and reviewed with sensible judgment. The study reveals that the fluid velocity reduces with incremental values of the viscoelastic parameter [Formula: see text] and magnetic strength. The temperature reduces for the suction parameter with the existence of stretchable but enhances with thermophoresis and Brownian motion effects. Heat transfer rate amplifies for [Formula: see text] but declines for [Formula: see text]. Mass transfer rate increases with the increase in Brownian parameter and Schmidt number. A comparative analysis shows a better agreement with previous results in limiting scenarios.

scholarly journals Determination of Zero Dimensional, Apparent Devolatilization Kinetics for Biomass Particles at Suspension Firing Conditions

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1018
Author(s):  
Anna Espekvist ◽  
Tian Li ◽  
Peter Glarborg ◽  
Terese Løvås ◽  
Peter Arendt Jensen
Keyword(s):  
Aspect Ratio ◽  
Particle Density ◽  
Fluid Dynamic ◽  
Particle Radius ◽  
Biomass Combustion ◽  
Least Squares Regression ◽  
Gas Temperature ◽  
Density Maximum ◽  
Parameter Ranges ◽  
The Impact

As part of the strive for a carbon neutral energy production, biomass combustion has been widely implemented in retrofitted coal burners. Modeling aids substantially in prediction of biomass flame behavior and thus in boiler chamber conditions. In this work, a simple model for devolatilization of biomass at conditions relevant for suspension firing is presented. It employs Arrhenius parameters in a single first order (SFOR) devolatilization reaction, where the effects of kinetics and heat transfer limitations are lumped together. In this way, a biomass particle can be modeled as a zero dimensional, isothermal particle, facilitating computational fluid dynamic calculations of boiler chambers. The zero dimensional model includes the effects of particle aspect ratio, particle density, maximum gas temperature, and particle radius. It is developed using the multivariate data analysis method, partial least squares regression, and is validated against a more rigorous semi-2D devolatilization model. The model has the capability to predict devolatilization time for conditions in the parameter ranges; radius (39–1569 μμm), density (700–1300 kg/m3), gas temperature (1300–1900 K), aspect ratio (1.01–8). Results show that the particle radius and gas phase temperature have a large influence on the devolatilization rate, and the aspect ratio has a comparatively smaller effect, which, however, cannot be neglected. The impact of aspect ratio levels off as it increases. The model is suitable for use as stand alone or as a submodel for biomass particle devolatilization in CFD models.

Mapping of protein fouling by FTIR-ATR as experimental tool to study membrane fouling and fluid velocity profile in various geometries and validation by CFD simulation

2008 ◽  
Vol 47 (7) ◽  
pp. 1106-1117 ◽  
Author(s):  
David Delaunay ◽  
Murielle Rabiller-Baudry ◽  
José M. Gozálvez-Zafrilla ◽  
Béatrice Balannec ◽  
Matthieu Frappart ◽  
...  
Keyword(s):  
Velocity Profile ◽  
Membrane Fouling ◽  
Cfd Simulation ◽  
Fluid Velocity ◽  
Protein Fouling ◽  
Experimental Tool
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