Effect of initial particle deposition rate on cake formation during dead-end microfiltration

2021 ◽  
Vol 618 ◽  
pp. 118672 ◽  
Author(s):  
Qi Han ◽  
Huang Teik Lay ◽  
Weiyi Li ◽  
Jia Wei Chew
Keyword(s):  
Deposition Rate ◽  
Particle Deposition ◽  
Initial Particle ◽  
Dead End ◽  
Cake Formation

Study on Deposition Motion of Naturally Circulating Particulate Matter in Supercritical Water Based on Factor and Correspondence Analysis

2021 ◽  
Author(s):  
Tian Qi ◽  
Tao Zhou ◽  
Ning Chen ◽  
Juan Chen
Keyword(s):  
Particle Size ◽  
Deposition Rate ◽  
Supercritical Water ◽  
Particle Deposition ◽  
Volume Fraction ◽  
Natural Circulation ◽  
Particle Volume Fraction ◽  
Heating Power ◽  
Axial Distance ◽  
Initial Particle

Abstract It is very important to study the deposition of particles in natural circulation of supercritical water to ensure the safe and stable operation of supercritical water reactor. The data of natural circulation loop calculated by ANSYS-CFX simulation software were analyzed by factorial analysis method, and the effects of axial distance, initial particle volume fraction, heating power and particle size on particle deposition were obtained. The results show that the contribution rate of particle size to the deposition rate is the largest, about 36.3%, and the contribution rate of initial particle concentration to the deposition rate is about 15.1%; the interaction between axial distance and heating power is the most obvious, and the interaction effect is the pipe temperature distribution. Through correspondence analysis, the main influencing factors of particle deposition rate at each level were analyzed. The results show that: when the deposition rate is small, the small change of axial distance will also have a greater impact on the deposition of particles; when the deposition rate is further increased, the change of initial particle volume fraction will significantly affect the deposition of particles; when the deposition rate is large, the particle size plays a leading role in the deposition of particles. Both of the two analysis methods show that: in the influence on the deposition of particles in supercritical water natural circulation, the influence degree is particle size > concentration > axial distance > heating power. Based on the two analysis methods, an analysis regression model is established and the volume proportion of particles in natural circulation is predicted.

Cake formation of bidisperse suspensions in dead-end microfiltration

2019 ◽  
Vol 577 ◽  
pp. 31-40 ◽  
Author(s):  
Qi Han ◽  
Thien An Trinh ◽  
Jia Wei Chew
Keyword(s):  
Dead End ◽  
Cake Formation ◽  
Bidisperse Suspensions

scholarly journals Airflow and Particle Deposition in Acinar Models with Interalveolar Septal Walls and Different Alveolar Numbers

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Jinxiang Xi ◽  
Mohamed Talaat ◽  
Hesham Tanbour ◽  
Khaled Talaat
Keyword(s):  
Deposition Rate ◽  
Particle Deposition ◽  
Orientation Angle ◽  
Structural Complexity ◽  
Particle Dispersion ◽  
Breath Holding ◽  
Complex Models ◽  
Tracking Model ◽  
Lagrangian Tracking ◽  
Collateral Ventilation

Unique features exist in acinar units such as multiple alveoli, interalveolar septal walls, and pores of Kohn. However, the effects of such features on airflow and particle deposition remain not well quantified due to their structural complexity. This study aims to numerically investigate particle dynamics in acinar models with interalveolar septal walls and pores of Kohn. A simplified 4-alveoli model with well-defined geometries and a physiologically realistic 45-alveoli model was developed. A well-validated Lagrangian tracking model was used to simulate particle trajectories in the acinar models with rhythmically expanding and contracting wall motions. Both spatial and temporal dosimetries in the acinar models were analyzed. Results show that collateral ventilation exists among alveoli due to pressure imbalance. The size of interalveolar septal aperture significantly alters the spatial deposition pattern, while it has an insignificant effect on the total deposition rate. Surprisingly, the deposition rate in the 45-alveoli model is lower than that in the 4-alveoli model, indicating a stronger particle dispersion in more complex models. The gravity orientation angle has a decreasing effect on acinar deposition rates with an increasing number of alveoli retained in the model; such an effect is nearly negligible in the 45-alveoli model. Breath-holding increased particle deposition in the acinar region, which was most significant in the alveoli proximal to the duct. Increasing inhalation depth only slightly increases the fraction of deposited particles over particles entering the alveolar model but has a large influence on dispensing particles to the peripheral alveoli. Results of this study indicate that an empirical correlation for acinar deposition can be developed based on alveolar models with reduced complexity; however, what level of geometry complexity would be sufficient is yet to be determined.

Fouling Behavior of Microstructured Hollow Fiber Membranes in Dead-End Filtrations: Critical Flux Determination and NMR Imaging of Particle Deposition

Langmuir ◽  
2011 ◽  
Vol 27 (5) ◽  
pp. 1643-1652 ◽  
Author(s):  
P. Zeynep Çulfaz ◽  
Steffen Buetehorn ◽  
Lavinia Utiu ◽  
Markus Kueppers ◽  
Bernhard Bluemich ◽  
...  
Keyword(s):  
Hollow Fiber ◽  
Particle Deposition ◽  
Nmr Imaging ◽  
Hollow Fiber Membranes ◽  
Critical Flux ◽  
Dead End ◽  
Fiber Membranes ◽  
Flux Determination

Simulation of Submicron Particle Deposition in Laminar and Turbulent Stagnation Point Flows

1991 ◽  
Author(s):  
Salem Abuzeid ◽  
Ahmed A. Busnaina
Keyword(s):  
Brownian Motion ◽  
Stagnation Point ◽  
Deposition Rate ◽  
Particle Deposition ◽  
Aerosol Particles ◽  
Laminar Flows ◽  
Wafer Surface ◽  
Particle Sizes ◽  
Mean Flow ◽  
Gaussian Random Process

Abstract The two dimensional laminar and turbulence stagnation-point flow over a wafer surface within a cleanroom environment are numerically simulated. This study shows the relationship between particle capture area on the wafer and the particle size and flow conditions. The mean flow field is simulated using a two equation k-ϵ turbulence model. Trajectories of aerosol particles are evaluated by solving the corresponding Lagrangian equation of motion that includes effects of drag, gravity, lift force, Brownian motion and turbulence fluctuations. The Brownian motion is modeled as a white noise process and turbulence fluctuation is assumed to behave as Gaussian random process. Simulations are carried out for aerosol particles (of various sizes) released at different locations over the surface. Depositions of particles on the wall are evaluated and a capture area which varies with particle sizes is produced. The results show that Brownian motion becomes very significant when turbulence fluctuations start to disappear near the wall for particles smaller than 1 μm in diameter. The results also show that, deposition of particles in turbulent flows are usually higher than that in laminar flows for all particle sizes considered. The effect of fluid on particle deposition rate is predicted for fluid of air and water. The results show that, particles deposition rate in air is higher than that in water.

Blower-door estimates of PM2.5 deposition rates and penetration factors in an idealized room

2020 ◽  
pp. 1420326X2094442 ◽  
Author(s):  
Yonghang Lai ◽  
Ian Ridley ◽  
Peter Brimblecombe
Keyword(s):  
Deposition Rate ◽  
Coefficient Of Variation ◽  
Particle Deposition ◽  
Experimental Methods ◽  
Test Cell ◽  
Deposition Rates ◽  
Penetration Factor ◽  
Surface Materials ◽  
Novel Method ◽  
Indoor And Outdoor

Particle deposition and penetration in buildings has been widely studied, but the effect of indoor characteristics merits further investigation, so improved experimental methods may be needed. The present study measured indoor and outdoor concentrations of PM2.5 and estimated PM2.5 deposition rates and penetration factors under a variety of different indoor situations, with a novel method (blower-door method). The blower-door method is compared with the standard decay and rebound method for an idealized room (a portable building test cell; 6.08 m [Formula: see text] 2.40 m [Formula: see text] 2.60 m) under eight testing scenarios (empty, cardboard boxes in three arrangements, terry cloth wall covering, and three sets of window holes); run three times to establish the coefficient of variation representing precision. Results show that higher induced indoor–outdoor pressure differences cause a larger variation of estimated effective deposition rate on different indoor surfaces. The deposition rate and penetration factor may be influenced by indoor surface materials. The blower-door method gives higher precision for the estimates, and detects subtle differences in penetration factors, which may be difficult using the decay and rebound method.

Effect of coagulation mechanisms on the fouling and ultrasonic cleaning of PTFE membrane

2012 ◽  
Vol 66 (11) ◽  
pp. 2291-2298 ◽  
Author(s):  
Meng-Wei Wan ◽  
Cybelle Morales Futalan ◽  
Cheng-Hung Chang ◽  
Chi-Chuah Kan
Keyword(s):  
Membrane Fouling ◽  
Permeate Flux ◽  
Cleaning Efficiency ◽  
Ultrasonic Cleaning ◽  
Ptfe Membrane ◽  
Pore Blocking ◽  
Dead End ◽  
Flux Decline ◽  
Cake Formation ◽  
Scanning Electron

In this study, the effect of coagulation pretreatment on membrane fouling and ultrasonic cleaning efficiency was investigated using a dead-end polytetrafluoroethylene (PTFE) microfiltration system. The extent of membrane fouling was examined under different coagulation mechanisms such as charge neutralization (CN), electrostatic patch effect (EPE) and sweep flocculation (SW). Fouling through EPE mechanism provided the greatest flux decline and least permeate flux recovery over CN and SW. EPE produces more stable, smaller and more compact flocs while CN and SW have large, easily degraded and highly-branched structured flocs. The predominant fouling mechanism of EPE, CN and SW is pore blocking, a combination of pore blocking and cake formation, and cake formation, respectively. Better permeate flux recovery is observed with SW over CN and EPE, which implies formation of less dense and more porous cake deposits. The morphology of fouled membranes was examined using scanning electron microscopy (SEM).

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