• 한국자동차공학회논문집
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• 제20권4호
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• pp.39-45
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• 2012

Today gasoline engines for vehicular application are not only faced with stringent emission regulation but also with increasing requirements to better fuel economy, while guaranteeing power density. The spray-guided type gasoline direct injection (GDI) engine has an advantage of improved thermal efficiency and lower harmful emissions. Centrally mounted high pressure injector and adjacent spark plug allow stable lean combustion due to the flexible mixture stratification. In the present study, the performance and emissions characteristics of developed spray-guided type GDI combustion system were evaluated at various excess air ratio conditions. The specific fuel consumption and nitrogen oxides ($NO_x$) emissions were reduced due to the achievement of stable lean combustion under flammability limit. Multiple injection strategy was not helpful to improve fuel consumption while further reduction of $NO_x$ emissions was possible.

• 한국대기환경학회지
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• 제34권2호
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• pp.356-365
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• 2018

While social networks have become very popular and powerful way of connecting people and sharing new information, they also effectively spread wrong or biased information to the public. We examine the so-called "Shandong peninsular rumor" that claims Chinese government is responsible for the increased air pollution in South Korea and Japan, by moving pollution-causing industries near Beijing to the Shandong peninsular which is close to South Korea. We demonstrate that the amounts of $NO_x$ and $SO_2$ emissions inferred by space-borne monitoring and regional air quality models show clear declining trends in past several years. We do not have any evidences to support the relation of Shandong peninsular emissions change to South Korean air quality.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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• pp.50-56
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• 2001

A study on the exhaust emissions of diesel engine with various fuel injection timing is peformed experimentally. In this paper, fuel injection timing is changed from BTDC $14^{\circ}$ to $20^{\circ}$ by $2^{\circ}$ intervals, the experiments are performed at engine speed 1800rpm and from load 25% to 100% by 25% intervals, and main measured parameters are fuel consumption rate, Soot, NOx. HC and CO emissions etc. The obtained conclusions are as follows (1) Specific fuel consumption is indicated the least value at BTDC $18^{\circ}$ of fuel injection timing and it is increased in case of leading the injection timing. (2) Soot emission is decreased in case of leading fuel injection timing and it is increased in the form of convex downwards with increasing the load. (3) $NO_x$ emission is increased in case of leading fuel injection timing and it is increased in the form of straight line nearly with increasing the load. (4) HC and CO emissions are decreased in case of leading fuel injection timing and they are changed in the form of convex downwards with increasing the load.

• International Journal of Automotive Technology
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• 제6권2호
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• pp.95-105
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• 2005

Diesel engines have low specific fuel consumption, but high particulate emissions, mainly soot. Diesel soot is suspected to have significant effects on the health of living beings and might also affect global warming. Hence stringent measures have been put in place in a number of countries and will be even stronger in the near future. Diesel engines require either advanced integrated exhaust after treatment systems or modified engine models to meet the statutory norms. Experimental analysis to study the emission characteristics is a time consuming affair. In such situations, the real picture of engine control can be obtained by the modeling of trend prediction. In this article, an effort has been made to predict emissions smoke and NO$_{x}$ using cylinder combustion derived parameters and diesel particulate filter data, with artificial neural network techniques in MATLAB environment. The model is based on three layer neural network with a back propagation learning algorithm. The training and test data of emissions were collected from experimental set up in the laboratory for different loads. The network is trained to predict the values of emission with training values. Regression analysis between test and predicted value from neural network shows least error. This approach helps in the reduction of the experimentation required to determine the smoke and NO$_{x}$ for the catalyst coated filters.

• 한국대기환경학회지
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• 제26권1호
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• pp.69-76
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• 2010

While increased use of motor cycles in the recent years for various demands could worsen air quality, only few studies have been conducted on estimation of emission factors and characterization of emissions from motorcycle. In this study, emissions from selected six models of motorcycle based on largest market share and production rate were investigated. To investigate gaseous and carbonaceous air pollutants, such as carbon monoxide (CO), total hydrocarbon (THC), nitrogen oxide ($NO_x$), elemental carbon (EC) and organic carbon (OC), total 124 motorcycles between 2003 and 2007 model year were tested with regulatory driving conditions, such as CVS-40 and CVS-47 mode. These motorcycles were further sub-categorized based on their displacement (< 50 cc, 50~150 cc, and $\geq$ 150 cc), type of stroke (2- and 4 strokes) and model year (2003~2005 and 2006~2007). Tested motorcycles with recent model year (2006~2007) exhibited less emissions of regulatory gaseous and carbonaceous air pollutants compared to old model year (2003~2005). Chemical analysis showed that CO present in highest concentration followed by THC and $NO_x$ for all tested motorcycles. Interestingly, two strokes motorcycle produced higher THC emission but less CO and $NO_x$ than those of four strokes. For all types of displacement and stroke, emission factors (gram per kilometer) of THC and CO except $NO_x$ with recent model year (2006~2007) showed decreased trend compared to old model year (2003~2005). In addition to this, due to mixed combustion between gasoline fuel and lubricant, two strokes motorcycle showed OC > EC emission trend.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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• pp.75-82
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• 2002

The effects of intake mixture temperature on performance and exhaust emissions under four kinds of engine loads were experimentally investigated by using a four-cycle four-cylinder, swirl chamber type, water-cooled diesel engine with scrubber EGR system operating at three kinds of engine speeds. The purpose of this study is to develop the scrubber exhaust gas recirculation(EGR) control system for reducing $NO_x$ and soot emissions simultaneously in diesel engines. The EGR system is used to reduce NOx emissions. And a novel diesel soot-removal device with a cylinder-type scrubber which has five water injection nozzles is specially designed and manufactured to reduce soot contents in the recirculated exhaust gas to the intake system of the engine. The influences of cooled EGR and water injection, however, would be included within those of scrubber EGR system. In order to study the effect of intake mixture temperature, a intake mixture heating device which has five heating coils is made of a steel drum. It is found that the specific fuel consumption rate is considerably elevated by the increase of intake mixture temperature, and that NOx emissions are markedly decreased as EGR rates are increased and intake mixture temperature is dropped, while soot emissions are increased with increasing EGR rates and intake mixture temperature.

• 대한기계학회논문집B
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• 제32권11호
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• pp.897-905
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• 2008

Selective catalytic reduction(SCR) is known as one of promising methods for reducing $NO_x$ emissions in diesel exhaust gases. $NO_x$ emissions react with ammonia in the catalyst surface of SCR system at working temperature of catalyst. In this study, to raise the reacting temperature when the exhaust gas temperature is too low, a heater is located at the bottom of SCR reactor. At an ambient temperature, ammonia is radially injected perpendicular to the exhaust gas flow at inlet pipe and uniformly mixed in the mixing area after being impinged against the wall. To predict the turbulent model inside the mixing area of SCR system, the standard ${\kappa}\;-\;{\varepsilon}$ model is applied. This work investigates numerically the effects of induced heat on the gaseous flow. The results show that the Taylor-$G{\ddot{o}}rtler$ type vortex is generated after the gaseous flow impinges the wall in which these vortices influence the temperature distribution. The addition of heat disturbs the flow structure in bottom area and then stretching flow occurs. Vorticity strand is also formed when heat is continuously increased. Constriction process takes place, however, when a further heat input over a critical temperature is increased and finally forms shed vortex which is disconnected from the vorticity strand. The strong vortex restricts the heat transport in the gaseous flow.

• 한국자동차공학회논문집
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• 제24권5호
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• pp.538-548
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• 2016

The purpose of this study is to identify the possibility of effective tuning works, understand the characteristics of tuning engine, and analyse the basic data of engine tuning inspection corresponding to the safe operation and environment of a driving gasoline car. The effects of tuning on the characteristics of performance and exhaust emissions under a wide range of engine speeds are experimentally investigated by the actual driving car with a four-cycle, four-cylinder DOHC, turbo-intercooler, water-cooled gasoline engine operating at four types of non-tuning, tuning 1, 2 and 3. The tuning parts in the gasoline engine are the intake manifold, intake pipe and air filter. In the experiment, the output, torque and air-fuel ratio of the five-speed automatic transmission vehicles were measured at the chassis dynamometer(Dynojet 224xLC) with one person on board. The exhaust emissions of $NO_X$, THC, CO, $O_2$ and $CO_2$, and excess air ratio(${\lambda}$) at the other chassis dynamometer(DASAN-MD-ASM-97-KR-HD) were also measured by the idle/constant-speed mode(ASM2525 mode) test method. It is found that the actual air-fuel ratios of non-tuning and tuning engines were shown to be lower than the stoichiometric air-fuel ratio with increasing engine speed, and the actual air-fuel ratio of non-tuning engine was slightly higher than those of tuning engines when the engine speed is more than 4000 rpm. The output was significantly increased by the tuning whereby the maximum output of tuning engine was more increased to approximately 117.64% than that of non-tuning engine. In addition, CO, THC and $NO_X$ emissions of non-tuning and tuning engines measured by the constant-speed test mode were all satisfied with the inspection standards. CO emission was increased, while THC and $NO_X$ emissions were reduced by tuning.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.88-94
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• 2012

One of the effective ways to reduce both $NO_x$ and PM at the same time in a diesel CI engine is to operate the engine in low temperature combustion (LTC) regimes. In general, two strategies are used to realize the LTC operation-dilution controlled LTC and late injection LTC - and in this study, the former approach was used. In the dilution controlled regime, LTC is achieved by supplying a large amount of EGR to the cylinder. The significant EGR gas increases the heat capacity of in-cylinder charge mixture while decreasing oxygen concentration of the charge, activating low temperature oxidation reaction and lowering PM and $NO_x$ emissions. However, use of high EGR levels also deteriorates combustion efficiency and engine power output. Therefore, it is widely considered to use increased intake pressure as a way to resolve this issue. In this study, the effects of intake pressure variations on performance and emission characteristics of a single cylinder diesel engine operated in LTC regimes were examined. LTC operation was achieved in less than 8% $O_2$ concentration and thus a simultaneous reduction of both PM and $NO_x$ emission was confirmed. As intake pressure increased, combustion efficiency was improved so that THC and CO emissions were decreased. A shift of the peak Soot location was also observed to lower $O_2$ concentration while $NO_x$ levels were kept nearly zero. In addition, an elevation of intake pressure enhanced engine power output as well as indicated thermal efficiency in LTC regimes. All these results suggested that LTC operation range can be extended and emissions can be further reduced by adjusting intake pressure.

• Korean Chemical Engineering Research
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• 제62권3호
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• pp.225-232
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• 2024

탄소 중립 사회로의 전환을 위해 전체 온실가스 배출량의 86.8%를 차지하는 에너지 생산 부문에서의 이산화탄소 배출량 감축이 필요하다. 현재 우리나라는 총 발전량의 60%를 석탄과 천연가스에 의존하고 있으며 이를 풍력, 태양광 등의 재생에너지로 대체하는 방법은 에너지 수급이 불안정하고 비용이 높다는 단점이 있다. 이를 해결하기 위해 본 연구에서는 기존에 사용되고 있는 NGCC(Natural Gas Combined Cycle) 공정을 기반으로 천연가스, 암모니아, 수소를 혼합하여 연소한다는 해결책을 제시하였다. 시뮬레이션을 수행한 결과, 이산화탄소 배출량을 효과적으로 줄일 수 있었으며 천연가스만을 연료로 이용해 얻은 전력량과 비교하였을 때 34%~238%의 전력을 얻었다. 천연가스, 암모니아, 수소의 질량분율에 대한 사례연구를 수행한 결과, 암모니아 비율이 증가할수록 발전량과 NO_x 배출량은 감소하였고 수소비율이 증가할수록 발전량과 NO_x 배출량은 증가하였다. 본 연구는 추후 다양한 혼합 연료의 조합 및 경제성 평가 등 혼합 연료 발전 분야의 가이드라인이 될 수 있을 것이다.