• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.78-85
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• 2007

Recently, diesel vehicles have been increased and their emission standards have been getting strict. The emission of diesel vehicles contains numerous dangerous compounds, especially particulate matters cause a serious environmental pollutant and affect to human health seriously. Thousands of studies have already reported that particulate matters are associated with respiratory and cardiovascular diseases, and death. Due to these, it is necessary to measure the soot concentration and soot particle size in laboratory flames or practical engines to recognize the soot formation, and develop the control strategies for soot emission. In this study, the characteristics of exhausted soot particle size and volume fraction from 2.0L CRDI diesel engine have been investigated as varying engine speed and load. Laser induced incandescence has been used to measure soot concentration. Time-resolved laser induced incandescence has been used to determine soot particle size in the engine. The soot volume fraction is increased as increasing engine load but soot volume fraction is decreased as increasing engine speed. The primary particle size is distributed about $35nm{\sim}60nm$ at each experimental conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.4
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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).

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.403-412
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• 2006

The effect of a wall temperature on the soot deposition process from a diffusion flame to a solid wall was investigated in a microgravity environment to attain in-situ observations of the process. The fuel for the flames was an ethylene ($C_2H_4$). The surrounding oxygen concentration was 35% with surrounding air temperatures of $T_a=600K$. In the study, three different wall temperatures. $T_w$=300, 600, 800K, were selected as major test conditions. Laser extinction was adopted to determine the soot volume fraction distribution between the flame and burner wall. The experimental results showed that the maximum soot volume fractions at $T_w$=300, 800 K were $8.8{\times}10^{-6},\;9.2{\times}10^{-6}$, respectively. However, amount of soot deposition on wall surface was decreased because of lower temperature gradient near the wall with increasing wall temperature. A numerical simulation was also performed to understand the motion of soot particles in the flame and the characteristics of the soot deposition to the wall. The results from the numerical simulation successfully predicted the differences in the motion of soot particles by different wall temperature near the burner surface and are in good agreement with observed soot behavior that is, the 'soot line', in microgravity.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.54-65
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• 1997

To quantify the LII signals from soot particle of flames in diesel engine cylinder, a new method has been proposed for correcting LII signal attenuated by soot particles between the measuring point and the detector. It has been verified by an experiment on a laminar jet ethylene-air diffusion flame. Being proportional to the attenuation, the ratio of LII signal at two different detection wavelengths can be used to correct the measured LIIsignal and obtain the unattenuated LII signal, from which the soot volume fraction in the flame can be estimated. Both the 1064-nm and frequency-doubled 532-nm beams from the Nd : YAG laser are used. Single-shot, one-dimensional(1-D) line images are recorded on the intensified CCD camera, with the rectangular-profile laser beam using 1-mm-diameter pinhole. Two broadband optical interference filters having the center wavelengths of 647 nm and 400 nm respectively and a bandwidth of 10 nm are used. This two-wavelength correction has been applied to the ethylene-air coannular laminar diffusion flame, previously studied on soot formation by the laser extinction method in this laboratory. The results by the LII measurement technique and the conventional laser extinction method at the height of 40 nm above the jet exit agreed well with each other except around outside of the peaks of soot concentration, where the soot concentration was relatively high and resulting attenuation of the LII signal was large. The radial profile shape of soot concentration was not changed a lot, but the absolute value of the soot volume fraction around outside edge changed from 4ppm to 6.5 ppm at r=2.8mm after correction. This means that the attenuation of LII signal was approximately 40% at this point, which is higher than the average attenuation rate of this flame, 10~15%.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.400-404
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• 2011

The activity and stability of the metal filter material Pt coated on NOx and soot oxidation were examined. The catalytic reaction test for NOx and soot were also performed independently and simultaneously. As a result, it showed the NO to $NO_2$ shift reaction with 20% conversion, NOx decomposition (about 10%) and perfect soot oxidation on the material Pt coated proceeded. Onset temperature of soot oxidation shift to lower temperature (about $30^{\circ}C$) by generated $NO_2$. The material also was less affected by thermal shock than $Pt/Al_2O_3$ or $Pt/TiO_3$ catalysts due to its stability of surface structure.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.178-182
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• 2010

Simultaneous removal reaction for NOx, soot over Pt catalysts using various $TiO_2$ as support was studied. The catalytic tests ware carried out injectin NO, soot, NO and soot simultaneously on each catalysts. As results, it showed different NOx removal efficiency and soot oxidation rate according to various kinds of $TiO_2$. Onset temperature of soot oxidation has a correlation to $NO_2$ generated for the independently performed NOx. It was investigated that NO to $NO_2$ oxidation was intimately related to crystallite size and surface area, and it has a tremendous impact on Pt aggregation on the catalyst surface and catalyst' reducibility. Therefore, we concluded that major index of the reaction was physico-chemical properties of catalyst' supports.

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.183-193
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• 2000

Soot formation and oxidation is closely related to the combustion phenomena inside a diesel engine. Laser-based diagnostics provide a means for improving our understanding of diesel combustion, because they have highly temporal and spatial ability. To understand the soot behavior we did preliminary study by taking flame luminosity photographs and 2-D images of soot distribution using Laser Elastic Scattering(LIS) and Laser-Induced Incandescence(LII). From the data we found that soot concentration was high in the bowl and disappeared from the central region in the late combustion stage and that soot exists in the flame using luminosity, LIS and LII.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.107-110
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• 2003

Characteristics of PAH and soot formation in coflow diffusion flames of methane, methane, propane, and ethylene have been experimentally studied to investigate the temperature and fuel structure effect on soot formation. PAH and soot images were acquired by applying PAH LIF and LII techniques, respectively and temperature was measured using R-type thermocouple. Direct photographs of soot particles have also been taken by transmission electron microscopy (TEM) through a thermophoretic sampling. Comparison of PAH and soot formation between the aliphatic fuels has shown the importance of fuel structure effect in diffusion flames.

• Journal of Mechanical Science and Technology
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• v.15 no.8
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• pp.1196-1204
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• 2001

The effects of EGR(Exhaust Gas Recirculation) on heavy-duty diesel engine performance, NO and soot emissions were numerically investigated using the modified KIVA-3V code. For the fuel spray, the atomization model based on the linear stability analysis and spray wall impingement model were developed for the KIVA-3V code. The Zeldovich mechanism for the formation of nitric oxide and the soot model suggested by Hiroyasu et al. were used to predict the diesel emissions. In this paper, the computational results of fuel spray, cylinder pressure, and emissions were compared with experimental data, and the optimum EGR rates were sought from the NO and soot emissions trade-off. The results showed that the EGR is effective in suppressing NO but the soot emission was increased considerably by EGR. Using cooled EGR, soot emission could be enhanced without worsening of NO.

• Journal of ILASS-Korea
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• v.19 no.4
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• pp.211-215
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• 2014

The main purpose of this study is to provide basic information of droplet soot generation of decane fuel. To achieve this, this paper presents the experimental results on the decane droplet combustion conducted under various ambient pressure($P_{amb}$), and oxygen concentration($O_2$) conditions. At the same time, the experimental study was conducted in terms of soot volume fraction($f_v$) and its maximum value. Also, visualization of single fuel droplet was conducted by high resolution CCD camera and ambient pressure($P_{amb}$) and oxygen concentration($O_2$) was changed by control system. It was revealed that higher ambient pressure($P_{amb}$), and oxygen concentration($O_2$) enhanced the soot generation and improved the maximum soot volume fraction( $f_v$).