• Particle and aerosol research
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• v.15 no.1
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• pp.1-13
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• 2019

Current desulfurization and denitrification technologies have reached a considerable level in terms of reduction efficiency. However, when compared with the simultaneous reduction technology, the individual reduction technologies have issues such as economic disadvantages due to the difficulty to scale-up apparatus, secondary pollution from wastewater/waste during the treatment process, requirement of large facilities for post-treatment, and increased installation costs. Therefore, it is necessary to enable practical application of simultaneous SOx and NOx treatment technologies to remove two or more contaminants in one process. The present study analyzes a technology capable of maintaining simultaneous treatment of SOx and NOx even at low temperatures due to the electrochemically generated strong oxidation of the wet-pulse complex system. This system also reduces unreacted residual gas and secondary products through the wet scrubbing process. It addresses common problems of the existing fuel gas treatment methods such as SDR, SCR, and activated carbon adsorption (i.e., low treatment efficiency, expensive maintenance cost, large installation area, and energy loss). Experiments were performed with varying variables such as pulse voltage, reaction temperature, chemicals and additives ratios, liquid/gas ratio, structure of the aeration cleaning nozzle, and gas inlet concentration. The performance of individual and complex processes using the wet-pulse discharge reaction were analyzed and compared.

• Journal of Environmental Health Sciences
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• v.23 no.4
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• pp.57-66
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• 1997

Successful energy conservation and good indcfor air quality (IAQ) are highly dependent on ventilation system. Air filtration is a primary solution of indoor air control strategies in terms of reducing energy consumption and improving ihdoor air quality. A conventional system with bypass filter, as it is called variable-air-volume/bypass filtration system (VAV/BPFS), is a variation of the conventional variable air volume (VAV) systems, which is designed to eliminate indoor air pollutant and to save energy. Bypass filtration system equipped with a high-efficiency particulate filter and carbon absorbent provides additional cleaned air into indoor environments and maintain good IAQ for human health. The objectives of this research were to compare the relative total decay rate of indoor air pollutant concentrations, and to develop a mathematical model simulating the performance of VAV/BPFS. All experiments were performed in chamber under the controlled conditions. The specific conclusions of this research are: 1. The VAV/BPFS system is more efficient than the VAV system in removing indoor air pollutant concentration. The total decay rates of aerosol, and total volatile organic compound (TVOC) for the VAV/BPFS system were higher than those of the conventional VAV system. 2. IAQ model predictions of each pollutant agree closely with the measured values. 3. According to IAQ model evaluation, reduction of outdoor supply air results in decreased dilution removal rate and on increased bypass filtration removal rate with the VAV/BPFS. As a results, we recommends the VAV/BPFS as an alternative to conventional VAV systems.

• Journal of the Korean Society of Visualization
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• v.22 no.1
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• pp.34-39
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• 2024

With the fine particulate matter (PM) poses a serious threat to public health and the environment. The ultrafine PM in particular can cause serious problems. This study investigates the effectiveness of a submicron dry fog system in removing fine PM. Two methods are used to create fine dust particles: burning incense and utilizing an aerosol generator. Results indicate that the dry fog system effectively removes fine dust particles, with a removal efficiency of up to 81.9% for PM₁₀ and 61.9% for PM_2.5 after 30 minutes of operation. The dry fog, characterized by a mean size of approximately 1.5 ㎛, exhibits superior performance in comparison to traditional water spraying methods, attributed to reduced water consumption and increased contact probability between water droplets and dust particles. Furthermore, experiments with uniform-sized particles which sizes are 1 ㎛ and 2 ㎛ demonstrate the system's capability in removing ultrafine PM. The proposed submicron dry fog system shows promise for mitigating fine dust pollution in various industrial settings, offering advantages such as energy consumption and enhanced safety for workers and equipment.

• Particle and aerosol research
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• v.14 no.4
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• pp.171-180
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• 2018

To optimize the shape of the electrostatic precipitator for the removal of particulate matter in subway environments, the wind-tunnel experiments were carried out to characterize collection efficiency and ozone emission rate. As a standardized parameter, power consumption divided by the square of flow velocity, was increased, the $PM_{10}$ collection efficiency increased. If the standardized parameter is higher than 1.0 due to high power consumption or low flow velocity, increase in thickness of electrodes from 1 to 2 mm, or increase in distance of collection plates from 5 to 10 cm did not change the $PM_{10}$ collection efficiency much. Increase in thickness of high-voltage electrodes, however, can cause decrease in $PM_{10}$ collection efficiency by 28% for low power consumption and high flow velocity. The ozone emission rate decreased as distance of collection plates became wider, because the ozone emission rate per unit channel was constant, and the number of collection channels decreased as the distance of collection plates increased. When the distance of collection plates was narrow, the ozone emission rate increased with the increase of the thickness of electrodes, but the difference was negligible when the distance of collection plates was wide. It was found that the electrostatic precipitator having a thin high-voltage electrodes and a narrow distance of collection plates is advantageous. However, to increase the thickness of high-voltage electrodes, or to increase the distance of collection plates is needed, it is necessary to increase the applied voltage or reduce the flow rate to compensate reduction of the collection efficiency.

• Journal of the Korean Electrochemical Society
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• v.8 no.2
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• pp.77-81
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• 2005

Porous-composite electrodes have been developed using silica gel, which reduce carbon aerogel usage with high cost. Silica gel powder was added to the carbon aerogel to simplify the manufacturing procedure and to increase the wet-ability, the mechanical strength and the CDI efficiency. Porous composite electrodes composed of carbon aerogel and silica gel powder were prepared by paste rolling method. Carbon aerosol composite electrodes with $10\times10cm^2$ are placed face to face between spacers, and assembled the four-stage series cells for CDI process. Each stage is composed of 45 cells. Four-stage series cells (flow through cells) for CDI process are put in continuous-system reactor containing 1,000ml-NaCl solution bath of 1,000 ppm. The four-stage series cells with carbon aerogel electrodes are charged at 1.2V and are discharged at 0.001V, and then read the current. Conclusively, removal efficiencies of ions using the four-stage series cells composed of carbon aerogel composite electrodes show good removal efficiency of $99\%$ respectively.

• KSBB Journal
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• v.22 no.3
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• pp.151-156
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• 2007

Increasing public concerns over odors and air regulations necessitates the remediation of a wide range of odorous compounds for industrial purpose. Currently, wet scrubbing technique by neutralization using essential oils is utilized to treat methyl mercaptan odor. The chemical analysis is performed to analyze the composition of an essential oil by GC-MS. The objective of this study is to clarify the possibility of the neutralization of odors sprayed in the fixed bed and determine the removal efficiencies in the misty aerosol by different input odor concentration. It is found that methyl mercaptan is significantly removed in the wet scrubber, and their removal efficiency of methyl mercaptan is obtained by 98%.

• Particle and aerosol research
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• v.13 no.1
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• pp.1-10
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• 2017

Accurate prediction of size, shape and velocity of a bubble rising through a liquid pool is very important for predicting the particulate removal efficiency in pool scrubbing, for designing engineering safety features to prepare for severe accidents in nuclear power plants, and for predicting the emission of fission products from MCCI (molten core-concrete interaction) process during severe accidents. In this review article, previous studies on the determination of the size, shape and rising velocity of a bubble in liquid are reviewed. Various theoretical and parameterization formulas calculating the bubble size, shape and velocity from physical properties of liquid and gas flowrate are compared. Recent studies tend to suggest simple parameterizations that can easily determine the bubble shape and rising velocity without iteration, whereas iteration has to be performed to determine the bubble shape and velocity in old theories. The recent parameterizations show good agreement with measured data obtained from experiments conducted using different liquid materials with very diverse physical properties, proving themselves to be very useful tools for researchers in related fields.

• Particle and aerosol research
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• v.12 no.4
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• pp.115-126
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• 2016

Numerical analysis was done to evaluate the movement of the particles and the fluid inside of the cyclone-bag hybrid dust collector. Flow discharged from the cyclone in the hybrid particle collector has swirl pattern, and it results in the biased flow to the bag filters and deteriorates the collection performance of the bag filter. The current study is to evaluate the effect of the duct lengths and the baffle arrays in the connection duct by the computational methods. Main concerns of the analysis are how to improve the uniformity of the internal flow between the cyclone and the bag filter. Numerical analysis was done to check the particle removal efficiencies of the system with respect to the flow characteristics which is expressed in RMS values of the upward flow inside of the connection duct. The flow pattern inside of the connection duct is evaluated under different the duct lengths and the baffle arrays. In case of the reference geometry the RMS value of inside flow was 56.7%, and the value was decreased to 30.1% by controlling the lengths of duct. The effects of baffle was also evaluated, the RMS value of flow could be decreased 55.2% and so on. But the pressure drop across the baffles becomes high and the system efficiency becomes lower.

• Particle and aerosol research
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• v.19 no.4
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• pp.101-110
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• 2023

In order to reduce particulate matters (PM) from marine diesel engines, we developed novel electrostatic diesel particulate matter filtration system. Electrostatic diesel particulate filtration (DPF) system consists of electrostatic charger and filtration part. The electrostatic charger and filtration part are composed of a metal discharge electrode and a metal fiber filter (porosity: 68.1-86.1%), respectively. In the electrostatic charger part, diesel soot particles are reduced by electrostatic force. The filtration part after electrostatic charger part reduces diesel soot particles through inertial and diffusion forces. The filtration efficiency of electrostatic DPF system was examined through the experiments using engine dynamometer system (300 kW) and ship (200 kW). The PM reduction efficiencies due to inertial and electrostatic forces showed about 70-75% and 80-90%, respectively, according to the RPM of the engine. The differential pressure of the electrostatic DPF system applied to the ship was about 1-9 mbar, which was less than the allowable differential pressure for ship engines in South Korea (100 mbar). The results show that the electrostatic DPF system is suitable for application to the PM reduction emitted from ships.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.12
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• pp.820-824
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• 2008

Electret filter media are used in general ventilation filters, disposable respirators, vehicle cabin filters, vacuum cleaners and room air cleaners. There are basic mechanisms of interception, inertial impaction, diffusion, gravitational settling, electrostatic attraction by which an aerosol particle can be deposited onto a fiber in a filter. The ability of fine particle removal strongly depends on the electrostatic forces between particles and polarized fibers. Thus, the stability of the fiber polarization is a major factor in the reliability of electret filters. In this study, the electret filter is made by electrospinning process using Polystyrene which is dissolved by 5 : 5 of Tetrahydrofuran (THF) and Dimethylformamide (DMF). Also the electrical properties and the filtration performances of electrospun filter media are Quantitatively investigated. Electrical properties of electrospun filters have been studied on surface charge potential and surface charge density. Also the filtration performance of the electret filters are evaluated on collection efficiency. The surface charge potential and the surface charge density of electrospun PS filters are increased with increasing applied voltage and saturated at 30 kV of applied voltage. Also collection efficiency of electro spun filters is increased with increasing surface charge potential and surface charge density. But the surface charge potential is decreased by natural decay and it causes deterioration of particle collection efficiency.