• Title/Summary/Keyword: Particle charging

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Numerical Evaluation of charged Liquid Particle′s Behavior in Fluid Flow and Electric Field and The Electric Effect on the Particle Dispersion (유동과 전기장 내에서의 액체입자의 거동과 전기장이 입자의 산란에 미치는 영향에 관한 수치적 연구)

  • Kim, Hyeong-Min
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.4
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    • pp.570-577
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    • 2002
  • Charged liquid particle's behavior in electric and flow field was simulated to define the effect of electric field on the contact area and its dispersion. For the simulation of flow and electric field finite volume method was applied. To find out the particle's moving path in that field lagrangian equation of motion was solved by Runge-Kutta methods. We assumed that the particle was charged 10% of Rayleigh limit while the particle passing through the electrode and the particle does not have an effect on the electric field. In case of 30[Kv] of voltage charging the particles injected from the central 60% of the nozzle injection area adhere to the grounded moving plate and no dispersion occurred. Increasing the charged voltage to 40[Kv], it brought about the same phenomena as that of 30[Kv] charging except the dispersion. Voltage increasing from 30[Kv] to 40 [Kv] caused higher Coulomb force acts on the particle and it made the particle dispersion.

Effects of Pulse Modulations on Particle Growth m Pulsed SiH4 Plasma Chemical Vapor Deposition Process (펄스 SiH4 플라즈마 화학기상증착 공정에서 입자 성장에 대한 펄스 변조의 영향)

  • Kim, Dong-Joo;Kim, Kyo-Seon
    • Journal of Industrial Technology
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    • v.26 no.B
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    • pp.173-181
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    • 2006
  • We analyzed systematically particle growth in the pulsed $SiH_4$ plasmas by a numerical method and investigated the effects of pulse modulations (pulse frequencies, duty ratios) on the particle growth. We considered effects of particle charging on the particle growth by coagulation during plasma-on. During plasma-on ($t_{on}$), the particle size distribution in plasma reactor becomes bimodal (small sized and large sized particles groups). During plasma-off ($t_{off}$), there is a single mode of large sized particles which is widely dispersed in the particle size distribution. During plasma on, the large sized particles grows more quickly by fast coagulation between small and large sized particles than during plasma-off. As the pulse frequency decreases, or as the duty ratio increases, $t_{on}$ increases and the large sized particles grow faster. On the basis of these results, the pulsed plasma process can be a good method to suppress efficiently the generation and growth of particles in $SiH_4$ PCVD process. This systematical analysis can be applied to design a pulsed plasma process for the preparation of high quality thin films.

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Particle Agglomeration of a Bipolar Charging System with a Control Grid (제어전극을 갖는 쌍극성 하전장치의 입자응집 특성)

  • Moon, Jae-Duk;Ahn, Chang-Jin
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.10
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    • pp.465-470
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    • 2005
  • In this paper. an experimental study, for method of increasing the efficiency of electrostatic precipitator for the collection of submicron-sized particles has been studied. All AC electric field was used to induce agglomeration of bipolory charged Particles. .4 bipolar AC-agglomeration system. consisted with a multineedle-mesh discharge system with a control grid, was proposed and investigated. Systematic experiments were carried out to investigate the agglomeration ratio of the AC-agglomeration system as a function of the different grid spacings and grid resistances for the submicron particles generated from liquid prorhane gas burning. The agglomeration ratios, which indicate the particle numbers before and after agglomeration of the test particles in number concentration base, were found to be 0.87, 1.80, 3.86, 9.50 and, 11.00 times for the particle sizes of 0.3. 0.5, 0.7, 1.0, and 2.0$\mu$m at applied voltage of 3.5kV, respectively which showed that the fine particle numbers were decreased while the larger particle numbers were increase greatly.

Numerical analysis of collection performance for electro-cyclone (전기싸이클론의 집진 성능 해석)

  • 김완수;강윤호;이진원
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.10 no.6
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    • pp.702-713
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    • 1998
  • The characteristics of flow and particle collection for an electrocyclone with a central wire inside a high efficiency Stairmand cyclone was numerically analysed. Turbulent flow field was modeled by the Reynolds stress model and solved with an FVM code FLUENT. Particle motion and in-situ charging were simultaneously solved by a Lagrangian integration with time. The flow field obtained was in good agreement with experiments in the outer region. The characteristics of collection enhancement due to electric force were well manifested and well explained based on first principles. The effect of the in-situ charging process was very similar to the case of a simplified assumption of saturated charging, and the effect of the hopper was proved negligible.

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Charge Depletion Effect on Collection Efficiency of an Electret Cabin Air Filter for Submicron Particles (승용차용 정전 필터 내의 정전 섬유의 보유 하전 감쇄에 의한 미세 입자 포집효율 변화)

  • Ji, Jun-Ho;Kang, Suk-Hoon;Hwang, Jung-Ho;Bae, Gwi-Nam
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.71-76
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    • 2001
  • An electret filter is composed of permanently charged electet fibers and is widely used in applications requiring high collection efficiency and low-pressure drop. In this work, the collection efficiency of the filter media used in manufacturing cabin air filters was investigated by using poly-disperse particles when submicron particles are loaded. Long-term experiments were conducted by applying different charging states, which are spray electrification and charge equilibrium by bipolar ionization. In order to investigate on the effect of particle loading in filter media, NaCl particles were generated from 0.1% and 1% solutions by an atomizer. In NaCl 0.1%, the collection efficiency of electret filter decreased and then did not change in equilibrium state. In the case of relative larger particles of NaCl 1%, collection efficiency for the equilibrium charged particles increases due to the particle loading on the filter fibers. Particles charged by spray electrification are small in collection efficiency after equilibrium state and increase of filter media's pressure drop was very low in comparison of the equilibrium charged particles.

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Corona ion Assisted Nano-Particle Morphology Control in an Atmospheric Pressure Furnace Reactor (대기압 반응로 내 코로나 이온을 이용한 나노입자 형상의 제어)

  • An, Gang-Ho;Yun, Jin-Uk;Kim, Yeong-Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.5
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    • pp.710-715
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    • 2002
  • The spherical nonagglomerated and uniform nanometer-size SiO$_2$particles are synthesized by the injection of TEOS vapor, irons and reaction gas in a furnace. Ions are generated by corona discharge and these ions charge SiO$_2$particles. As a result, spherical, nonagglomerated and ultrafine particles are generated in various conditions. Their morphology, charging portion and size distribution are examined by using TEM, ESP and SMPS. As the applied voltage of electrode changes from 0 to 5.0 kV, it is observed that the melon diameter of SiO$_2$particle decreases from 94 nm to 42 nm.

Numerical Study of Particle Collection and Entrainment in Electrostatic Precipitator (집진기내 입자 포집과 비산 문제에 대한 수치적 연구)

  • Kim, Ju-Hyeon;Kweon, Soon-Cheol;Kwon, Ki-Hwan;Lee, Sang-Hwan;Lee, Ju-Hee
    • The KSFM Journal of Fluid Machinery
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    • v.15 no.1
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    • pp.27-35
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    • 2012
  • A numerical simulation for particle collection efficiency in a wire-plate electrostatic precipitator (ESP) has been performed. Method of characteristics and finite differencing method (MOC-FDM) were employed to obtain electric field and space charge density, and lattice boltzmann method (LBM) was used to predict the Electrohydrodynamic (EHD) flow according to the ion convection. Large eddy simulation (LES) was considered for turbulent flow and particle simulation was performed by discrete element method (DEM) which considered field charging, electric force, drag force and wall-collision. One way coupling from FDM to LBM was used with small and low density particle assumption. When the charged particle collided with the collecting plate, particle-wall collision was calculated for re-entertainment effect and the effect of gravity force was considered.

Characteristics of Ultrafine SiO$_2$Particle Synthesized by Electro-Hydrodynamic Spray Injection in a Furnace (반응로내 전기-수력학적 분사에 의한 비응집 초미세 SiO$_2$ 입자 합성과 특성)

  • Yun, Jin-Uk;Yang, Tae-Hun;An, Gang-Ho;Choe, Man-Su
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.5
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    • pp.660-665
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    • 2001
  • Ultrafine particles have been widely used in many high technology industrial areas. The spherical nonagglomerated and uniform nanometer-size SiO$_2$particles are synthesized by the direct injection of TEOS(Tetraethyorthosilicate) using electro-hydrodynamic spraying method. Electro-hydrodynamic spraying can generate submicron-size TEOS droplets having high electric charges by applying a high electric field between the liquid injection nozzle and the reaction tube. These TEOS droplets are evaporated, and thermally decomposed or oxidized to produce nanometresized SiO$_2$particles in the reaction tube. Spherical, nonagglomerated and ultrafine particles are generated in various conditions and examined by using SEM and SMPS. As the total gas flow rate in the furnace changes from 1.5 lpm, the mean diameter of SiO$_2$particle decreases from 120 nm to 68 nm. The synthesized particle charging fractions are also investigated.