• 한국대기환경학회지
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• 제28권5호
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• pp.506-517
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• 2012

Electronic Toll Collection System (ETCS), so called "Hi-Pass" in Korea, has improved traffic flow at toll gate of highways. It is known that the improvement of traffic flow should reduce air pollutants and $CO_2$ from vehicles. In this study, real driving emission of a light duty truck with Portable Emission Measurement System(PEMS) has been measured to evaluate the emission reduction effect due to ETCS. The correlations between driving variables and emissions have been analyzed to verify its effect on traffic flow improvement and emission reduction at toll gate. We considered average vehicle speed, Relative Positive Acceleration (RPA), and the distance of queue as driving variables. Compared to passing Manual Toll Collection System (MTCS) lane without queue, ETCS was able to reduce 38.7% of $NO_x$, 21.6% of soot, and 27.7% of $CO_2$. The results showed that the higher the average vehicle speed, the lower RPA and no queue in ETCS contributed to the emission reductions. Linear equation models with RPA and queue have been established by the multiple linear regression method. The linear models resulted in the higher coefficient of determination than those with only average vehicle speed used for establishing vehicle emission factors.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.16-23
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• 2011

Low temperature combustion is one of the advanced combustion technology in an internal combustion engine to reduce soot and nitrogen oxides simultaneously. In present experiment three kinds of injector were used to investigate the influence of injection angle and number of nozzle holes on the low temperature combustion in a heavy duty diesel engine. Low temperature diesel combustion is realized from the exhaust gas recirculation rate of 60%. Indicated mean effective pressure of low temperature combustion corresponds to the 70% level of conventional diesel engine combustion. Reduction of hydrocarbon and carbon monoxide, which are produced in low temperature combustion because of the low combustion temperature and a deficit of oxygen, was achieved by using various injector configuration. The result of experiment with $100^{\circ}$ injection angle and 8 holes showed that reductions in hydrocarbon and carbon monoxide could be achieved 58% and 27% respectively maintaining the 7% increased indicated mean effective pressure in low temperature diesel combustion compared with conventional injector.

• Journal of Advanced Marine Engineering and Technology
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• 제34권3호
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• pp.360-368
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• 2010

A SCR catalytic filter system is used for reducing $NO_x$ and soot emissions simultaneously from diesel combustors. The amount of ammonia (as a reducing agent) must be controlled with the amount of $NO_x$ to obtain an optimal $NO_x$ conversion. Hence, gas mixing between ammonia and exhaust gases is vital to ensure that the SCR catalyst is optimally used. If ammonia mass distribution is not uniform, slip potential will occur in rich concentration areas. At lean areas, on the other hand, the catalyst is not fully active. The better mixing is indicated by the higher uniformity of ammonia mass distribution which is necessary to be considered in SCR catalytic filter system. The ammonia mass distributions are depended on the flow field of fluids. In this study, the velocity field of gaseous flow is investigated to characterize the transport of ammonia in SCR catalytic filter system. The influence of different injection placements on the ammonia mass distribution is also discussed. The results show that the ammonia mass distribution is more uniform for the injector directed radially perpendicular to the main flow of inlet at the gravitational direction than that at the side wall for both laminar (Re = 640) and turbulent flows (Re = 4255). It is also found that the mixing index decreases as increasing the heating temperature in the case of ammonia injected at the side wall.

• 한국자동차공학회논문집
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• 제20권5호
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• pp.102-112
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• 2012

The vast stores of biomass available in the worldwide have the potential to displace significant amounts of fuels that are currently derived from petroleum sources. Fast pyrolysis of biomass is one of possible paths by which we can convert biomass to higher value products. The wood pyrolysis oil (WPO), also known as the bio crude oil (BCO), have been regarded as an alternative fuel for petroleum fuels to be used in diesel engine. However, the use of BCO in a diesel engine requires modifications due to low energy density, high water contents, low acidity, and high viscosity of the BCO. One of the easiest way to adopt BCO to diesel engine without modifications is emulsification of BCO with diesel and bio diesel. In this study, a diesel engine operated with diesel, bio diesel (BD), BCO/diesel, BCO/bio diesel emulsions was experimentally investigated. Performance and gaseous & particle emission characteristics of a diesel engine fuelled by BCO emulsions were examined. Results showed that stable engine operation was possible with emulsions and engine output power was comparable to diesel and bio diesel operation. However, in case of BCO/diesel emulsion operation, THC & CO emissions were increased due to the increased ignition delay and poor spray atomization and NOx & Soot were decreased due to the water and oxygen in the fuel. Long term validation of adopting BCO in diesel engine is still needed because the oil is acid, with consequent problems of corrosion and clogging especially in the injection system.

• 대한기계학회논문집B
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• 제36권11호
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• pp.1065-1072
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• 2012

바이오디젤 연료는 그 안에 포함된 산소성분으로 인해 압축착화엔진에 사용했을 때 일반디젤 연료보다 더 적은 입자상 물질을 배출한다. 따라서 이 연료를 저온연소 기법에 적용하는 경우 보다 효과적으로 $NO_x$-PM을 동시 저감할 수 있고 그로부터 저온연소 운전영역의 확장을 기대할 수 있다. 이번 연구에서는 일반디젤과 대두유 기반의 바이오디젤 연료를 이용하여 산소농도 5~7%의 Dilution controlled regime에서 저온연소 운전을 구현하고 성능 및 배기 특성을 조사하였다. 엔진 실험 결과로부터 바이오디젤 연료의 경우 디젤에 비해 약 14% 낮은 발열량에도 불구하고 높은 세탄가 및 함산소 성질로 인한 연소효율 증가로 동일 연료량 분사 시 이보다 더 낮은 약 10~12% 정도의 출력이 감소함을 볼 수 있었다. 배기 측면에서도 바이오디젤 내 산소원자가 입자상물질의 산화반응을 촉진하여 최대 90%의 smoke 저감이 가능함을 관찰하였다. 또한 엔진 과급 실험으로부터 과급을 사용하여 저온연소 및 바이오디젤 사용으로 인한 출력 저하를 개선할 수 있음을 확인하였으며 과급과 바이오디젤 연료의 동시 적용을 통해 산소농도 11~12%의 EGR 가스 투입으로도 저온연소에 상응하는 PM-$NO_x$ 동시 저감이 가능함을 보여주었다. 이런 결과는 결국 이와 같은 과급 및 바이오디젤 연료의 적절한 조합으로부터 엔진 출력 향상과 배기특성 개선이 동시에 달성할 수 있고 이로부터 운전영역의 확대가 가능함을 의미한다.

• 한국분무공학회지
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• 제19권4호
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• pp.155-166
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• 2014

This review will be concentrated on the spray characteristics of bioethanol and its derived fuels such as ethanol-diesel, ethanol-biodiesel in compression ignition (CI) engines. The difficulty in meeting the severe limitations on NOx and PM emissions in CI engines has brought about many methods for the application of ethanol because ethanol diffusion flames in engine produce virtually no soot. The most popular method for the application of ethanol as a fuel in CI engines is the blending of ethanol with diesel. The physical properties of ethanol and its derivatives related to spray characteristics such as viscosity, density and surface tension are discussed. Viscosity and density of e-diesel and e-biodiesel generally are decreased with increase in ethanol content and temperature. More than 22% and 30% of ethanol addition would not satisfied the requirement of viscosity and density in EN 590, respectively. Investigation of neat ethanol sprays in CI engines was conducted by very few researchers. The effect of ambient temperature on liquid phase penetration is a controversial topic due to the opposite result between two studies. More researches are required for the spray characteristics of neat ethanol in CI engines. The ethanol blended fuels in CI engines can be classified into ethanol-diesel blend (e-diesel) and ethanol-biodiesel (e-biodiesel) blend. Even though dodecanol and n-butanol are rarely used, the addition of biodiesel as blend stabilizer is the prevailing method because it has the advantage of increasing the biofuel concentration in diesel fuel. Spray penetration and SMD of e-diesel and e-biodiesel decrease with increase in ethanol concentration, and in ambient pressure. However, spray angle is increased with increase in the ethanol percentage in e-diesel. As the ambient pressure increases, liquid phase penetration was decreased, but spray angle was increased in e-diesel. The increase in ambient temperature showed the slight effect on liquid phase penetration, but spray angle was decreased. A numerical study of micro-explosion concluded that the optimum composition of e-diesel binary mixture for micro-explosion was approximately E50D50, while that of e-biodiesel binary mixture was E30B70 due to the lower volatility of biodiesel. Adding less volatile biodiesel into the ternary mixture of ethanol-biodiesel-diesel can remarkably enhance micro-explosion. Addition of ethanol up to 20% in e-biodiesel showed no effect on spray penetration. However, increase of nozzle orifice diameter results in increase of spray penetration. The more study on liquid phase penetration and SMD in e-diesel and e-biodiesel is required.

• 한국가스학회지
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• 제23권6호
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• pp.90-96
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• 2019

셰일가스의 채굴량 확장과 러시아를 통한 PNG (Pipeline Natural Gas)의 도입은 천연가스가 유력한 대체 연료임을 시사해주고 있다. 따라서 향후 증대될 천연가스의 공급에 맞추어 해당 연료의 수요처 증대가 필수적인 상황이다. 이와 같은 상황에서 수송분야는 저탄소 기체 연료인 천연가스를 적용하기 적합한 분야이며, 이를 통해 이산화탄소와 입자상 물질 등의 유해 배기물질을 저감하는 데 큰 역할을 할 것으로 기대된다. 천연가스는 자발화 특성이 낮고, 내노킹(Anti-knocking)성이 우수하기 때문에 전기점화 방식에 적합하다. 최근 가솔린 엔진은 연비 개선을 위해 연소실에 직접 분사하는 방식을 주로 채택하고 있으나,연소실 내로 액상 직분사를 하는 반면 천연가스의 경우 액상분사 혹은 고압 분사가 어렵다. 따라서 포트에 분사하는 방식을 사용하므로 동등 흡기압력에서 연료의 분율이 흡입공기의 체적을 대체하여 가솔린 직분 방식에 비해 출력이 저하되는 현상을 피할 수 없게 된다. 이에 본 연구에서는 터보차저를 천연가스 포트 분사 엔진에 적용하여 흡기 압력 상향을 통한 출력 보상을 도모하고자 하였다.그 결과 천연가스 적용 시 흡기압력을 기존 가솔린 대비 5-27 % 상향 시 가솔린 직분사 엔진과 동등 출력을 확보함과 동시에 향상된 제동 열효율을 확인 할 수 있었다.