• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.113-121
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• 1999

Diesel particulate matter is known to be one of the major harmful emissions produced by diesel engines. Diesel particulates are subject to diesel emission regulations and have lately become the focus in the diesel emission control technology. Thus, the aftertreatment system is adopted at the diesel engine exhaust to reduce the particulate emission. Although this benefit is recognized, it is not clear how the aftertreatment system influences quantitatively the particle size distribution distribution. In this study, the particle size distributions of diesel exhaust were measured using the scanning mobility particle sizer with and without the aftertreatment system. There results showed that the diesel particulate filter and plasm system reduced the number of emitted particles by more than 90% and about 80% respectivley in the particle size range of 20nm∼600nm. On the other hand no significant effect of the diesel oxidation catalyst on the particle number concentration was detected.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.124-129
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• 2010

The direct injection (DI) diesel engine has become a prime candidate for future transportation needs because of its high thermal efficiency. However, nitrogen oxides (NOx) increase in the local high temperature regions and particulate matter (PM) increases in the diffusion flame region within diesel combustion. Therefore, the demand for developing hybrid system consist of exhaust gas recirculation (EGR) and aftertreatment system as well as diesel particulate filter (DPF) or lean NOx trap (LNT) should be applied. The variation of EGR rate due to the malfunction of EGR valve can affect not only the combustion stability of engine but also the performance of aftertreatment system. In this research, 2.0 liter 4-cylinder turbocharged diesel engine was used to investigate the combustion and emission characteristics for various operating conditions with EGR. While the fuel consumption was increased with increase of EGR rate, NOx emission was improved by maximum 90% at low speed, low load operating condition. To achieve combustion stability and reliability of aftertrearment system with minimum penalty in fuel consumption and emissions, the fault diagnosis of EGR malfunction must be employed.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.8-15
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• 2001

An aftertreatment system of diesel exhaust gas was attempted to extract particulate matters. The system consisted of a corona-less electrostatic precipitator to agglomerate soot particles and a counter-flow cyclone to collect them. When the effect of high voltage was examined at different configuration of electrode plates, the case of positive 15kV at both plates showed the maximum reduction of 38% in diesel smoke level. However, the back pressure became quite high as engine speed increased, so that minimizing pressure drop in cyclone should be studied with improving collection efficiency of soot particles.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.2
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• pp.225-236
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• 2004

Diesel engines which emit a lot of PM and NOx have been known as a main air polluter. Especially, diesel particulate matters (OPM) including black smoke are hazardous air pollutants to human health and environment. The nations retaining advanced engine technologies have reinforced emission regulations. To meet these regulations diesel engine manufacturers have developed low-emission diesel engines, aftertreatment equipments, alternative fuel technologies and so on. In this study, particle number concentrations characteristics according to particle size and engine driving conditions were analyzed when these low-emission technologies were applied. There was a tendency of increasing particle number concentrations from heavy-duty diesel engines with increasing engine rpm and load rate. In the cases of COPF (Catalytic Diesel Particulate Filter), CNG (Compressed Natural Gas) engine and ULSD (Ultra Low Sulfur Diesel) more than 99% of particle number concentration were removed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.6
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• pp.97-103
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• 2003

Currently, due to serious increase of pollution scones, lots of technology has been involved to reduce exhaust gas in diesel engine. But the amounts of exhaust gas can not be decreased somehow due to the increase of diesel vehicles. Moreover, emission standards of each counties are being stringent in advanced countries such as USA and Europe. In the near future, sulfur contents in fuel must be essentially reduced f3r health and environment because sulfur can basically reduce exhaust gas. Therefore, when will be applied to Bio-diesel and ULSD, they could reduce sulfur contents of fuel without aftertreatment and might conform the influence of engine performance, emission, smoke and fuel consumption.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.16-21
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• 1999

The diesel vehicle is relatively superior to gasoline vehicle on the fuel consumption, durability and combustion efficiency. However, exhaust emission from diesel vehicle are known to be harmful to human health and environment. The treatment technologies for the diesel exhaust gases are classified as replacement of fuel, quality control of diesel fuel, improvement of engine and aftertreatment system. The most effective for the treatment technology is known to be aftertreatment system, and this research is continuously conducted by many groups. The DOC system has many advantages of reducing particulates and harmful gaseous substances such as CO. HC. Moreover, it is simple in device structure, relatively low cost, and easy to install witout retrofitting the vehicle. In this study, experiment were conducted to analyze the effects on factors of oxidation characteristics and conversion efficiency of DOC. In experiment, test was conducted to estimate engine emission in 11,000cc diesel engine which was equipped with DOC.

• Journal of Institute of Convergence Technology
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• v.1 no.1
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• pp.41-47
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• 2011

With the world-wide demand on the emission minimization, the needs on the diesel aftertreatment devices with high efficiency are also increasing. In order to effectively develop or design a high-performance diesel particulate filter, a clear understanding on the deposition and regeneration mechanism is required. In the present study, a theory on the lumped parameter model for wall-flow type diesel particulate filters is described focusing on the deposition efficiency, pressure drop inside the filter. The fourth order explicit Runge-Kutta method is utilized for the mass flow rate computation. Engine operation modes with controlled and uncontrolled regeneration options are selected. The computational lumped parameter model is validated by comparing the computed results with the measured data.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.796-802
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• 2005

Numerical analysis has been conducted for improving air flow characteristics in the exhaust aftertreatment system of diesel-fueled passenger cars by changing axial length and cone shape of a DPF diffuser. The results of air velocity and static pressure distributions along with air flow uniformity results suggest that a diffuser shape with 2D or 3D function type is better for air flow patterns in front of a DPF.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.110-119
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• 2008

Computer methods with simplified mathematical models in conjunction with empirical model parameters can be efficiently practiced into an optimization of a diesel aftertreatment system. Components of prime interests are diesel particulate filter, diesel oxidation catalyst and de-$NO_x$ catalytic converter. de-$NO_x$, de-PM, and de-HC processes in each part are individually modeled, formulated and then combined into an integrated analysis procedure for a unified simulation of the diesel emission aftertreatment. The model is empirically tuned and validated with comprehensive engine and laboratory data. The effects of emission species and space velocity on the $NO_x$ and soot reductions are parametrically investigated. A lowered $NO_2/NO_x$ ratio due to PM oxidation in DPF contributes to promote the $NO_x$ reduction by SCR at intermediate gas temperatures. $NO_x$ reduction is inert to the PM oxidation at high temperatures. Rate of PM trapping strongly depends on temperature and $NO_x$ concentration.

• Journal of the korean Society of Automotive Engineers
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• v.23 no.1
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• pp.20-26
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• 2001