The Effects of cooled and hot EGR(exhaust gas recirculation) on the characteristics of smoke and NOx emission have been investigated using a single cylinder, water-cooled, four cycle, DI diesel engine at several loads and speeds. In this study, a manually controlled EGR system was installed on a agricultural diesel engine which was operated at various operating system. And, the effects of hot EGR and cooled EGR on smoke and NOx emission were compared. The results showed that cooled EGR method was more effective than hot EGR method on smoke and NOx emission.

Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions from diesel engine are recognized main cause which influenced environment strong. In this study, the potential possibility of biodiesel and oxygenates additives (dimethoxy methane) was investigated as an alternative fuel for a naturally aspirated direct injection diesel engine. The smoke emission of blending fuel(biodiesel 90vol-% + DMM 10vol-%) was reduced in comparison with diesel fuel, that is, it was reduced approximately 70% at 2500rpm, full load. But, power, torque and brake specific energy consumption didn't have no large differences. But, NOx emissions withg biodiesel and DMM blended fuel had been increased compared with commercial diesel fuel.

The goal of this study is to propose the effective method of investigating the injurious factors and making improved plans that prevents the workers against musculoskeletal disorders at an diesel engine manufacturing company and the same business field with similar working conditions and process. A questionnaire were adopted to analyze the symptoms of workers' musculoskeletal disorders, and an ergonomic assessment method such as RULA, OWAS were performed to find out harmful factors of workplace and working posture. Based on the result of the evaluation, to enhance the working environment, improvement of worktable, working space, tools, and outfit was suggested, and induction of mechanical system was also suggested. It can be concluded that the method and process described in this paper could be helpful for diagnosing the musculoskeletal disorders and making improvement plans to the diesel engine fuel injection system manufacturing company and the same business field with similar working conditions and process.

In this study, the potential possibility of oxygenates on butyl ether(below BE) was investigated as an combustion activator for a direct injection diesel engine. It tested to estimate change of engine performance and exhaust emission characteristics for the diesel fuel and oxygenates additives blended fuel which has four kinds of blended ratio. The smoke of blended fuel(diesel fuel 80vol-%+BE 20vol-%) was reduced in comparison with diesel fuel, that is, it was reduced approximately 26%. And, power, torque and brake specific fuel consumption(BSFC) didn't have no large differences. But, NOx of BE blended fuel was increased compared with diesel fuel.

There are increased in using the bio-ethanol, as the carbon neutral attracts many researchers due to a reduction in carbon dioxide spotted as the global warming gas. A gasoline engine with 100% of the bioethanol was developed and used in Brazil already, but researches of using the bio-ethanol in diesel engines are lack. In this study, combustion tests with blend fuel of the gas oil and bio ethanol by 50% maximally due to a low cetane number of bio-ethanol were accomplished as a basic study of introduction of using the bioethanol in diesel engines. The result was that smoke emission was decreased with increase in proportion of the bio-ethanol, due to the increase of a amount of pre-mixed combustion with ignition delay. Although the amount of CO2 is reduced according as the bio-ethanol is used(carbon neutral), the emission of CO2 with increase in the proportion of the bio-ethanol was more increased due to lower a heat value of bio-ethanol than gas oil.

An emergency diesel generator(EDG) manufactured by a French company Wartsila SACM is a tandem type engine and consisted of two 10 cylindered diesel engines on each side. The maintenance manual provided by the manufacturer recommends that engine bearing be inspected every 15 years. However, it is difficult to inspect them because the manhole located in the lower compartment of the engine is too small for maintenance worker to access engine internals. Furthermore, the EDG should be disassembled and then overturned to inspect bearings unlike other EDG type. Such process will take longer period time than ordinary maintenance period. So it is not possible to inspect the main engine bearing and crank shaft during a routine or scheduled maintenance. In this paper, five methods are proposed and estimated to resolve the problem and the optimal maintenance method is chosen among them. The proposed optimal maintenance plan makes it possible to perform proper maintenance during regular maintenance period and to lower maintenance cost considerably.

In this paper, the effect of oxygen component in fuel on the exhaust emissions has been investigated for an indirect injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenate additive blended fuel which has four kinds of mixed ratio. Ethylene glycol mono butyl ether(EGBE) contains oxygen component 27% in itself, and it is a kind of effective oxygenated fuel of mono-ether group that the smoke emission of EGBE is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at higher loads in a IDI diesel engine.

Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions of diesel engines are recognized as main causes of the air pollution. DI diesel engine is widely used for the sake of minimization on exhaust emission. Because biodiesel fuel is a renewable and alternative fuel for diesel engine, its usability is expanded. The smoke emission of esterfied rapeseed oil is reduced remarkably in comparison with commercial gas oil, that is, it was reduced approximately 44.5% at 1500rpm. But, brake specific energy consumption showed very slight differences. It was concluded that esterfied rapeseed oil can utilize effectively as an alternative and renew-able fuel for diesel engine.

The potential possibility of oxygenated fuel for di-ether group oxygenated additives such as Methyl tertiary butyl ether(MTBE) and diethylene glycol dimethyl ether(DGM) were investigated for the sake of exhausted smoke reduction from diesel engine. They include oxygen content approximately from 18% to 36%, it is a kind of oxygenated fuel that the smoke emission of them is reduced remarkably compared with commercial diesel fuel. In the experiment by gas chromatography, unburned hydrocarbons of oxygenated fuel were reduced than those of commercial diesel fuel.

산유국으로부터 에너지 독립을 하고 대기오염방지를 위한 배기배출물을 저감시키기 위하여 대체연료에 많은 관심을 가지고 있다. 폐유나 새로운 식물성 기름과 동물성 기름으로부터 생성할 수 있는 바이오디젤유가 압축점화기관인 디젤기관에 구조적인 변화없이 사용될 수 있다. 이 논문에서는 4행정 직접분사식 디젤기관을 이용하여 순수 디젤유와 바이오디젤 혼합유(바이오디젤 10% 및 20% 함유)의 연료소비율과 배기배출물에 미치는 영향을 제시했으며, 특히 실험에 사용된 바이오디젤 연료는 우리 실험실에서 유채유로부터 직접 생산되었다. 이 연구 결과 바이오디젤 혼합유가 디젤유 보다 연료소비율과 질소산화물은 약간 증가 되었고 일산화탄소와 매연은 상당히 감소되었다.

Bio-diesel as fatty acid methyl ester was derived from such oils as soybean, peanut and canola oil by lipase catalyzed continuous trans-esterification. So the activation of lipase(Novozym - 435) was kept to be up to 4:1, the limiting molar ratio of methanol to oil under one-step addition of methanol due to the miscibility of oil and methanol through the static mixer for 4hrs and the elimination of glycerol on the surface of lipase by 7wt% silica gel. Therefore the overall yield of fatty acid methyl ester from soybean oil appeared to be 98% at 50·C of reaction temperature under two-steps addition of methanol with 2×2:1 of methanol to oil molar ratio at an interval of 5.5hrs, 7wt% of lipase, 24 number of mixer elements, 0.2ml/min of flow rate and 7wt% of silica gel.