• Journal of the Korean Society of Industry Convergence
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• v.23 no.1
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• pp.101-106
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• 2020

Along with dust collection efficiency, pressure loss is a very important cyclone operation factor. A severe rise in pressure loss causes the problem of cost. To solve the problem, the method connecting axial-vane type cyclones in parallel is suggested recently. The axial vane type cyclone dust collector applied in this study is a small portable type. Multiple cyclones are installed in a round type. The basic performance test on the axial vane type cyclone dust collector was conducted. As a result, the cut size reduced along with a rise in the wind velocity of the cyclone dust collector inlet. According to the test on dust collection efficiency, the effect of dust collection began to appear in the range of 3㎛ and dust collection efficiency was greatly improved at 5 ㎛. The noise of the cyclone dust collector well met the fan sound power level of KSB 6361.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.3
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• pp.243-254
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• 1996

The main purpose of this study is to investigate the collection efficiency characteristics of a cylindrical ESP. To do that, it is necessary to analyze the electric field, gas flow field, and mechanism of particle movement by numerical simulation based on EHD model. For a gas flow field, Navier-Stokes equation involving the electric source term was solved by SIMPLE algorithm. In case of the electric field, the current continuity and electric field equations were solved by S.O.R. method. The analysis of particle movement was performed on the basis of PSI-CELL model from the Lagrangian viewpoint. The results showed that the influence on the gas flow field by the electric field is almost negligible in a cylindrical ESP. The particle drift velocity $V_P$ toward the collection surface is increased continuously by the electrostatic force due to the rise of particle charge as the particle is moving to the flow direction and the particle size becomes larger. The collection efficiency is to quitely higher with the increase of applied voltage for the same particle size, while becomes smaller as the inlet velocity is increased.

• Particle and aerosol research
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• v.19 no.3
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• pp.63-76
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• 2023

An electrostatic precipitator (ESP) has a low pressure drop and a high collection efficiency but its collection efficiency can be reduced due to dust accumulation on the collection plates during long-term operations. In order to maintain the initial dust collection efficiency, it is necessary to periodically clean the collection plates. The common cleaning methods are using physical impacts or water sprays. These cleaning methods can lead to damage to the collection plate or generate wastewater. Herein, we implemented an electrodynamic screen (EDS) for ESP cleaning and evaluated its surface cleaning performance of particles. The EDS is an electrostatic system that can electrostatically repel particles on surfaces, allowing it to clean the ESP without causing damage and wastewater generation. Our evaluation included the analysis of the effects of AC voltage characteristics, electrode configuration and environmental conditions on the cleaning performance of the EDS with the aim of achieving effective surface cleaning. It has been demonstrated that activating the EDS cleans up to 65% of the particles on the surface, which indicates about 94% of our target cleaning zone.

• Particle and aerosol research
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• v.17 no.2
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• pp.21-27
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• 2021

We developed non-metallic electrodes that can replace metallic electrodes of the electrostatic precipitator(ESP) for the purpose of light weight, corrosion resistance, cost reduction. We manufactured three types of collection electrodes made of stainless steel (M), Carbon ink coating layer-Plastic sheet-Carbon ink coating layer (CPC), and Plastic sheet-Carbon ink coating layer-Plastic sheet (PCP). We studied the collection efficiency of a two-stage ESP using oil mist particles with and without collection stage by changing the flow rate, the material of collection electrode, and the applied voltage of the pre-charger module and the collection module. Here we measured concentrations of particles at diameters of 0.45 ㎛ (CMD; count median diameter) and 3.0 ㎛ (MMD : mass median diameter), as well as PM_2.5 and PM₁₀. As a result of the experiment, two-stage ESP had 22~25% higher collection efficiency in PM_2.5 than one-stage ESP at the same applied voltage. The difference in collection efficiency by varying the materials of collection electrodes was less than 5%. The weight of the non-metallic electrode was only one eighth the weight of the metal electrode. CPC electrode had a thickness of 0.27 mm, which was 1.5 times thinner than a thickness of PCP electrode, so when the flow rate increased, the CPC electrodes couldn't be kept at equal intervals due to the fluttering unlike PCP electrodes. In addition, the PCP-CPC collection module of the present experiment followed the theoretical efficiency based on Deutsch equation and Cochet's charging theory.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.2
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• pp.241-245
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• 2008

Non-volatile RAM (NVRAM) has both characteristics of nonvolatility and byte addressability. In order to efficiently exploit this NVRAM in the file system layer, we proposed the MiNV (Metadata in NVram) file system in our previous research. MiNV file system maintains all the metadata in NVRAM while storing file data in NAND Flash memory. In this paper, we experimentally analyze the efficiency for the execution of garbage collection in the MiNV file system. Also, we quantify the file system performance gains obtained from efficient garbage collection. Experimental results show that garbage collection on the MiNV file system executes more efficiently that on YAFFS even though these file systems adopt exactly the same garbage collection policy. Specifically, the MiNV file system invokes the aggressive garbage collection mechanism less frequently than YAFFS. Additionally, the MiNV file system postpones the first execution of the aggressive garbage collection mechanism in our experiments. From the experiments, we verify that the efficiency of garbage collection leads to performance improvements of the MiNV file system.

• Korean Journal of Veterinary Service
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• v.44 no.4
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• pp.217-225
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• 2021

We investigated the effect of temperature and stock density on the collection efficiency of oral fluid in the pig farm in Korea. Three pig farms with similar breeding environmental conditions were selected and four pens of each farm (total 12 pens) were tested for the collection efficiency of oral fluid from pigs. Collection rate was considered as significant when oral fluid was collected from 70% of pigs within a pen. In the case of growing pigs, when internal temperature of pig barn increased by one designated degree (5℃), the oral fluid collection rate significantly decreased by 24.7% (P<0.05). The collection rate of oral fluid also decreased by 7.1% (P<0.05) as the density rate increase by one designated degree (12.5%). It was estimated that the collection efficiency of oral fluid decreased when the internal temperature of pig barn was 30℃ or higher, or barn density is higher 25% or high. On the other hand, in the case of stall-housing sows, unlike growing pigs, there was no significant differences according to the temperature, so oral fluid collection was considered to be efficient even in hot season.

• Journal of Environmental Science International
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• v.8 no.2
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• pp.183-187
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• 1999

The purpose of this study is providing basic data to control the air pollutants from solid waste incinerator. Incinerating the waste wood, the electrostatic precipitator had the best collection efficiency. The leather incineration had the same collection efficiency as synthetic resin incineration. And the coarse particle collection efficiency was high. As you know in correlation of leather incineration. pollutants produced a from incinerator are mostly fine particles. If the scrubber used only in the process produced a lot of fine particles. It is adequate to use the above control devices, together with high efficiency collector like bag-filter. To select the adequate control devices, it is required to investigate the size distribution before establishing control devices.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.90-95
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• 2020

The purpose of this study is to numerically evaluate the collection performance of an ultra-small Lapple cyclone separator for 1~10 ㎛ particles introduced at flow rate of 10 L/min. The numerical evaluation reveals that a static pressure drop occurs more dominantly inside of the cyclone separator than at the inlet and the vortex finder. Also a fluid flow in the cyclone separator is confirmed to have a helical structure heading upward in the center of cyclone separator and downward in the vicinity of wall. The investigation on dust collection efficiency of the Lapple cyclone separator shows that particles of 4~8 ㎛ diameters are collected at very lower efficiency than other sizes. Then, the cut-point diameter of the cyclone separator is 1.48 ㎛.

• 연구논문집
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• s.34
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• pp.21-28
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• 2004

In this study, we report an investigation for the charging and collection of aerosol nanoparticles in an electrostatic precipitator (ESP) according to particle charging and diffusion effects. The competition between charging probability and diffusion effect determines the collection efficiency of nanoparticles in the ESP. In conclusion, collection efficiency continuously decreased with the reduction in the particle size. This indicates that poor partial charging effect of nanoparticles is more dominant than their diffusion effect in the ESP for the nanoparticles in the particle size range of 4-20 nm. Theoretical calculations using a unipolar diffusion charing theory were in good agreement with the experimental data for the nanoparticles less than 20 nm in diameter.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1795-1800
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• 2004

DOS and NaCl aerosol particles with geometric mean diameter of $0.1{\sim}3.0{\mu}m$ geometric standard deviation of $1.1{\sim}1.8$ and total number concentration of $450{\sim}400$ $particles/cm^3$ were used to determine collection efficiencies of a duct-type wet scrubber with respect to particle size. The tested operating variables included air velocity and water injection rate. It was shown from the experimental results that the collection efficiencies increased with increasing water injection rate and decreasing air velocity. It was also seen that the collection efficiency of the Duct-type wet scrubber is mainly governed by the mechanism of inertial impaction.