• International Journal of Automotive Technology
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• 제7권4호
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• pp.501-508
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• 2006

The effect of chemical additives, such as dimethyl ether(DME), ethanol, carbon disulfide on the soot formation were examined numerically. ill this study, the Frenklach soot mechanism was used as a base mechanism to predict the soot formation in the ethane flame. The combination of Westbrook's DME mechanism, Marinov's ethanol mechanism, and chemical kinetic mechanism for hydrogen sulfide and carbon disulfide flames was made with the base mechanism because the DME, ethanol, $CS_2$ additives are added into the ethane fuel. CHEMKIN code was used as a numerical analysis software to simulate the effect of chemical additives on reduction of the polycyclic aromatic hydrocarbons(PAH's) which are soot precursors. From the numerical results it is observed that addition of DME, ethanol and $CS_2$ into ethane fuel can reduce PAH species significantly. That means theses additives can reduce soot formation significantly. Results also strongly suggest suppression of soot formation by these additives to be mainly a chemical effect. Hand OH radicals may be the key species to the reduction of PAH species for additives.

• 대한기계학회논문집B
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• 제25권4호
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• pp.496-506
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• 2001

The effect of corona discharge on soot emission was experimentally investigated. Size and number concentrations of soot aggregates were measured and compared for various voltages. Regardless of the polarity of the applied voltage, the flame length decreased and the tip of flame spreaded with increasing voltage. For the experimental conditions selected, the flame was blown off toward the ground electrode by corona ionic wind. When the negative applied voltage was greater than 3kV(for electrode spacing = 3.5cm), soot particles in inception or growth region were affected by the corona discharge, resulting in the reduction of number concentration. The results show that the ionic wind favored soot oxidation and increased flame temperature. Number concentration and primary particle size greatly increased, when the corona electrodes were located the region of soot nucleation or growth(close to burner mouth).

• International Journal of Automotive Technology
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• 제3권1호
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• pp.17-26
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• 2002

The authors have reported significant reductions in particulate emissions of diesel engines by generating strong turbulence during the combustion process. This study aims to identify optimum conditions of turbulent mixing for effective soot reduction during combustion. The experiments were conducted with a constant volume combustion vessel equipped with abet-generating cell, in which a small amount of fuel is injected during the combustion of the main spray. The jet of burned gas from the cell impinges the main flame, causing changes In the mixing of fuel and air. Observation was made for a variety combinations of distances between spray nozzle and Jet orifice at different directions of impingement. It Is shown that compared with the case without Jet flame soot decreases when the jet impinges. When the jet is very close to the flame, it penetrates the soot cloud and causes little mixing. There were no apparent differences in the combustion duration when the direction of impingement was varied, although the mechanisms of soot reduction seemed different. An analysis of local turbulent flews with PIV (Particle image Velocimetry) showed the relationship between the scale of the turbulence and the size of the soot cloud.

• 한국입자에어로졸학회지
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• 제8권3호
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• pp.99-110
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• 2012

In the SCR (selective catalytic reduction) system which is used for controlling the NOx emission from the Diesel engines, the soot deposited on the catalysis causes degradation of the system performance. Numerical study was done to evaluate the performance of soot blower which is proposed as a method for removing the soot on the catalysis. The spray conditions and the effect of the compressed air from the AIG (air inlet gun) were analyzed numerically to evaluate the overall effective method of the soot blowing. The characteristics of the final velocity distribution and velocity waves across the inlet section of the catalysis were evaluated with respect to the geometries of the AIG outlets and pressure conditions. An experimental model was used to validate the results of the numerical calculation that is used for finding the effective removal blowing momentum transfer quantities of soot the inlet section of the catalysis, and it is proposed that the required minimum blowing momentum transfer quantities are over than 0.499 $kg/m{\bullet}t_{eff}$ in the current study.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.541-543
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• 2004

An optimal soot blowing system has been developed for an optimal operation of power utility boilers by both minimization of the use of steam and the number of soot blowers worked during soot blowing. Traditionally, the soot blowing system has been operated manually by operators. However, it causes the reduction of power and thermal performance degradation because all soot blowers installed in the plant should be worked simultaneously even there are lots of tubes those are not contaminated by slagging or fouling. Heat transfer area is divided into four groups, furnace, convection area including superheater, reheater and economizer, and air preheater in the present study. The condition of cleanness of the tubes is calculated by several parameters obtained by sensors. Then, a part of soot blowers works automatically where boiler tubes are contaminated. This system has been applied in a practical power plant. Therefore, comparison has been done between this system and manual operation and the results are discussed.

• Journal of Mechanical Science and Technology
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• 제20권1호
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• pp.1-12
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• 2006

This work reviews the effects of catalyst formulation and exhaust gas composition on soot oxidation in CDPF (Catalytic Diesel Particulate Filter). DOC's (Diesel Oxidation Catalysts) have been loaded with Pt catalyst (Pt/$Al_{2}O_3$) for reduction of HC and CO. Recent CDPF's are coated with the Pt catalyst as well as additives like Mo, V, Ce, Co, Fe, La, Au, or Zr for the promotion of soot oxidation. Alkali (K, Na, Cs, Li) doping of metal catalyst tends to increase the activity of the catalysts in soot combustion. Effects of coexistence components are very important in the catalytic reaction of the soot. The soot oxidation rate of a few catalysts are improved by water vapor and NOx in the ambient. There are only a few reports available on the mechanism of the PM (particulate matter) oxidation on the catalysts. The mechanism of PM oxidation in the catalytic systems that meet new emission regulations of diesel engines has yet to be investigated. Future research will focus on catalysts that can not only oxidize PM at low temperature, but also reduce NOx, continuously self-cleaning diesel particulate filters, and selective catalysts for NOx reduction.

• 대한기계학회논문집B
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• 제22권4호
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• pp.468-480
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• 1998

The temporal and spatial distributions of soot volume fractions were measured for single toluene droplet flames as a function of pressure under the normal-gravity condition. In order to characterize the transient nature of the flame and sooting regions, a full-field light extinction and subsequent tomographic inversion technique was used. The reduction in sooting as a function of pressure was assessed by comparison of the maximum soot volume fractions at several vertical positions along the axis above the droplet. The maximum soot volume fraction was reduced by 70% when the pressure was reduced by 60% from 1 atm to 0.4 atm. The reduction in sooting is attributed to variation of the geometric configuration of flame which reduces the system Grashof number as well as only the change in the adiabatic flame temperature as the pressure decreases. The gravimetrically-measured total soot yield was also compared to the optically-measured soot volume fraction to obtain a correlation between the two measurements. As a result, the total soot yield was linearly proportional to the optically-measured maximum soot volume fraction and linearly reduced as the pressure decreased. Accordingly, the non-intrusive full-field light extinction-measurements were able to be calibrated not only to measure soot volume fraction, but to simultaneously evaluate the total soot yield emitted from the toluene droplet flame (which is useful in the practical application).

• 한국분무공학회지
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• 제7권1호
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• pp.7-13
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• 2002

This paper is study on simultaneous reduction of NOx and soot for direct injection diesel engine using high and low cetane fuels. The stratified injection system was applied for diesel engine to use high and low cetane fuel. In this study, diesel fuel was used as high cetane fuels, methanol was used as low cetane fuels. Some parts of the injection system, ie. Nozzle holder. delivery vale, was remodeled to inject dual fuel sequentially from one injector. The leak injection quantity ratio of dual fuel was certificated by volumetric ratio at injection quantity experiment. According as concentration of low cetane fuel was varied, combustion experiment was performed using Toroidal and Complex chamber. Also, exhaust gas and fuel consumption were measured at the same time. Simultaneous reduction of NOx and soot was achieved at complex chamber regardless of concentration of low cetane fuel. However, according as concentration of low cetane fuel was increased, THC and CO was increased.

• Journal of Mechanical Science and Technology
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• 제15권9호
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• pp.1311-1318
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• 2001

It is necessary to diagnose accurately the characteristics of soot formation and oxidation in a diesel engine. Whereas past measurement techniques for soot concentration give limited information for soot, laser-based two-dimensional imaging diagnostics have a potential to provide temporally and spatially superior resolved measurements of the soot distribution. The technique using laser sheet beam has been applied to an optically accessible diesel engine for the quantitative measurement of soot. The results provided the information for reduction of soot from the diesel engine. Both LIS (Laser Induced Scattering) and LII (Laser Induced Incandescence) techniques were used simultaneously in this study. The images of LIS and LII showed the quantitative distribution of the soot concentration in the diesel engine. In this study, several results were obtained by the simultaneous measurements of LIS and LII technique. The diameter and number density of soot in combustion chamber of the test engine were obtained from ATDC 20 degree to 110 degree. The soot diameter increased about 37% between ATDC 20 degree and 110 degree. The number density of soot, however, decreased significantly between ATDC 40 degree and 70 degree.

• 한국기계가공학회지
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• 제18권8호
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• pp.74-81
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• 2019

Cars are inspected in the transport sector for their ability to achieve the greenhouse gas reduction targets. A vehicle (automobile) inspection broadly consists of regular and total checks, and both the safety level and the amount of exhaust gas are checked simultaneously during a vehicle inspection. This study deals with the efficiency of a soot probe to measure soot emissions from diesel vehicles. When the vehicle exhaust gas measurement is performed, there may be a difference between the exhaust gas temperature and the soot suction amount because of the different shape and angle of the exhaust port for each vehicle type. This may result in some incidents where the correct inspection nonconforming vehicle is not selected. Therefore, in this study, the shape of the probe was improved to increase the soot measurement efficiency under the condition of the exhaust pipe angle change.