The Effect of Particle Size on the Movement of a Striped Pattern Deposition Layer in an Aerosol Flow.

Aerosol Science and Technology

Tanaka

et al. 2000

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Formation of particle deposition layers on rough wall surfaces was studied as a simultaneous phenomenon of particle deposition and reentrainment. The test powders used were alumina of micron sizes and the experiments were conducted under turbulent aerosol flows. After particle deposition and reentrainment reached an equilibrium state, deposition layer of a striped pattern was formed. The striped pattern was characterized by the interval and the thickness, which decreased with increasing the roughness of wall surface. Further, the striped deposition layers moved slowly downstream, and the velocity of the moving deposition layers decreased with increasing the surface roughness. A moment balance model was used to explain the effect of the surface roughness on the velocity of the moving deposition layers.

Section: Moment Balance Of Separation and Adhesionmentioning

confidence: 94%

Simultaneous Phenomenon of Particle Deposition and Reentrainment: Effects of Surface Roughness on Deposition Layer of Striped Pattern

Adhiwidjaja

Aerosol Science and Technology

Tanaka

et al. 2000

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“…In addition, the striped deposition layer that formed on the vibrating wall moved downstream steadily. The same phenomenon occurs on the non-vibrating wall [20,21,23]. This is explained as follows: (i) small aggregates are reentrained from the front part of the striped deposition layer due to the aerodynamic drag and the collision of aerosol particles with the deposition layer, and (ii) aerosol particles deposit on the back part.…”

Section: Particle Deposition Layer Formed On a Non-vibrating Wallmentioning

confidence: 83%

“…In powder handling, a particle deposition layer is often formed in a pneumatic pipeline and small aggregates are mainly reentrained from the deposition layer. In recent years, the formation process of the particle deposition layer in turbulent aerosol flow has been studied under various conditions [19][20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Effects of wall vibration on particle deposition and reentrainment in aerosol flow

Theerachaisupakij

Advanced Powder Technology

Kataoka

et al. 2002

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The simultaneous phenomenon of particle deposition and reentrainment on a vibrating wall has been studied experimentally. Aerosols that were generated by dispersing alumina powder, of size 3.8-12.5 m mass median diameter, were transported into a vertical glass tube equipped with a vibration motor. The formation process of the particle deposition layer in the tube was observed through a digital video camera with a zoom lens. The experimental results showed that wall vibration was effective to enhance particle reentrainment. Critical flow velocity for the case of no particle layer formation decreased with increasing vibration acceleration and/or particle diameter. In contrast, at a velocity below the critical value, the wall vibration increased the amount of particles deposited on the wall. The critical condition for no particle layer formation under wall vibration was explained using a moment balance model.

“…Therefore, to clarify the simultaneous phenomenon, the formation process of the deposition layer and equilibrium states between deposition and reentrainment should be analyzed. From this point of view, we have studied the formation of the particle deposition layers and found several new facts [6][7][8][9]. A filmy deposition layer formed at a lower air velocity changed into a striped pattern deposition layer as the air velocity increases, and the thickness and the interval of the striped deposition layers were varied corresponding to the operational conditions.…”

mentioning

confidence: 99%

Simultaneous phenomenon of particle deposition and reentrainment in charged aerosol flow — effects of particle charge and external electric field on the deposition layer

Adhiwidjaja

Advanced Powder Technology

Yabe

et al. 2000

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Formation of particle deposition layer has been investigated as a simultaneous phenomenon of particle deposition and reentrainment in a turbulent aerosol flow. Aerosol particles passed through a corona charger were pneumatically transported into a glass tube equipped with a ring-type electrode, and the deposition layers formed on the tube wall in various conditions were quantitatively analyzed with particular attention to the effects of particle charge and external electric field on the deposition layer. The charged particles formed a filmy deposition layer around the electrode being independent of the polarity of particle charge and applied voltage. The mass of deposition layer increased with elapsed time and became constant after an equilibrium state of particle deposition and reentrainment. The time dependence was represented by an exponential equation; the time constant decreased with increasing particle charge and/or applied voltage, and the equilibrium mass of deposition layer increased with the particle charge. Furthermore, it was found that appropriate arrangement of electrodes to control external electric field eliminates the filmy deposition layer.