• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.45-51
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• 2015

In order to meet the enforced emission regulations and reduce fuel consumption, various new technologies are employed in engines. The problem of NOx emissions under a lean mixture condition should be solved, because a lean-burn direct-injection engine can realize stable lean combustion with a stratified mixture, which results in improvements in fuel economy and emissions. This study investigated the effects of intake and exhaust valve timing changes on the performance and emission characteristics of a lean-burn LPG direct-injection engine. Under a partial-load operating condition without throttling, an increase in the intake valve opening led to an increase in NOx emissions due to an increase in the amount of excess air. The fuel consumption deteriorated with an increase in the exhaust valve opening due to a decrease in the expansion work and an increase in the pumping loss.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.21-27
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• 2015

In order to meet the current emission regulations (EURO-6), it is necessary to significantly reduce $CH_4$ and $NO_X$ emissions. This study investigated the effect of a reduction in the valve overlap on the combustion and emission characteristics of a hydrogen-compressed natural gas engine under a part-load operating condition. The combustion and emission characteristics were analyzed for each fuel using the original camshaft and an altered camshaft with reduced valve overlap. The results showed that the thermal efficiency was decreased and the fuel flow was increased when using the altered camshaft. The $CO_2$ and $CH_4$ emissions were increased as a result of the reduced thermal efficiency. Under lean operating conditions, the $NO_X$ emission was decreased compared with one of the conventional camshaft. Thus, under the same fuels and operating conditions, it had a harmful influence on the emission characteristics and thermal efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.5
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• pp.596-603
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• 2003

Present study has been conducted to see the relative effects of adding N: to fuel-side and air-side on flame structure, soot formation and NOx emissions. Experiments were carried out to ascertain to what degree chemical kinetics and/or molecular transport effects can explain the differences in soot formation and NOx emission by studying laminar diffusion flames. Direct photograph was taken to see the flame structure. CARS techniques was used to get the flame temperature profiles. And spatial distribution of soot could be obtained by PLII method. CHEMKIN code was also used to estimate the global residence time to predict NOx emissions at each condition. Results from these studies indicate that fuel-side dilution is more effective than air-side dilution in view of NOx emissions. However, air-side dilution shows greater effectiveness over fuel-side dilution in soot formation. And turbulent mixing and heat transfer problems were thought to be considered in practical applications.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.183-188
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• 2017

This study deals with $de-SO_X$ and $de-NO_X$ process of a wet scrubber for small size ship engines. The experiment was conducted according to the E3 mode of the $NO_X$ technical code. In order to discharge the sulfur containing flue gas, ditertiarybutyldusulfide was added to the diesel fuel to increase the sulfur content. NO gas, which occupies most of the nitrogen oxides in the exhaust gas, was oxidized into $NO_2$ and absorbed by a wet scrubber. The developed equipment of this work achieved 100% of removal efficiency for highly soluble $SO_2$ gas in an aqueous solution.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.5
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• pp.525-530
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• 2013

In this study, the generator engine of training ship M/S "HAE RIM" of Kunsan National University which is being operated for 20 years was used in the experiment. The experiment was carried out under the engine speed of 1200rpm, then the load was varied 30 kW intervals from 0 to 90 kW and the injection timing was varied $2^{\circ}$CA intervals from BTDC $19^{\circ}$ to $23^{\circ}$CA. In the case of advancing fuel injection timing from BTDC $21^{\circ}$CA to $23^{\circ}$CA, specific fuel consumption is decreased by 1.37%, NOx is increased by 11.59 %, soot is decreased by 23.5 % and $SO_2$ is decreased by 2.8 %. Accoring to the analysis of effects of fuel injection timing on combustion & exhaust emissions characteristics on an old marine diesel engine, it is proved that the optimum fuel injection timing is BTDC $23^{\circ}$ which is $2^{\circ}$ faster than that of original injection timing.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.7
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• pp.70-75
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• 2005

In this study, experimental investigations were conducted on NOx emission characteristics with fuel swirl flow in swirl combustor. Many types of vanes, which altered air and fuel swirl angles, were employed to verify the mixing processes. For strong air swirl, fuel counter-swirl resulted in relatively large turbulent intensity, high energy to the high frequency region and narrow width of high temperature region compared with co-swirl condition. These effects of fuel counter-swirl resulted in low NOx emission characteristics at strong air swirl condition. And NOx reduction mechanism was also discussed.

• Journal of the Korean Institute of Gas
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• v.19 no.4
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• pp.22-28
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• 2015

In order to keep the competitiveness of LPG fuel for transportation fuel, the difference in fuel consumption with gasoline and cost for an aftertreatment system should be reduced with continuous development of technology for LPG engine. In the present study, spray-guided type direct injection combustion system, whose configuration is composed of direct injector in the vicinity of spark plug, was employed to realize stable lean combustion. A certain level of nitrogen oxides($NO_x$) emits due to a locally rich mixture regions in the stratified mixture. With the application of EGR system for the reduction of $NO_x$, 15% of $NO_x$ reduction was achieved whereas fuel consumption and hydrocarbon emission increased. By the application of EGR, the combustion speed reduced especially appeared at initial flame development period and peak heat release rates and increasing rates for heat release rate decreased as EGR rate increased due to the dilution effect of intake air.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.308-315
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• 2013

Water emulsion technology has the problem of unstable combustion due to the rapid separation of water. To solve the problem, a hybrid mixing device was developed. The device attached on the burner was tested. As a result, the fuel consumption reduced to 12% in the similar condition of exhaust emissions and flame temperature, and 45.5%, 98.5% and 97.2% of NOx, CO, and smoke were reduced at the same inlet air and fuel flow rate.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.1
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• pp.103-108
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• 2015

Recent global warming has been recognized as the world economy development from fossil fuel use is the culprit. This study was reduce the fossil fuel has been developed in a number of alternative energy, As a fuel that can be produced in our country is a biofuel. Biofuels is a sustainable fuel having economically benefits and decreasing environmental pollution problems caused due to fossil fuel. A lot of research is progressing about the conversion of diesel biofuel as renewable clean energy. In this experiment were remodel the institution that has been used in fishing engine again produced an experimental apparatus were installed directly, were studied using various bio fuel like to help the economically and environmentally sound operation of the vessel. rapeseed oil, soybean oil, comprehensively analyzing the results the effects of the exhaust emission characteristics of the waste rapeseed oil is available in a marine engine with similar physical and chemical components of the fuel, and the fuel consumption ratio, NOx is slightly increased, but soot was confirmed a tendency to decrease much.

• Journal of the korean Society of Automotive Engineers
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• v.18 no.6
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• pp.33-39
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• 1996

최근 서울의 일부 지역에서는 오존 주의보에 의한 대기 오염의 수치가 발표되고 있어 이의 심각성이 대두되고 있다. 대기오염의 주범은 자동차이며, 자동차에서 주로 많이 배출되는 질소산화물(NOx)과 탄화수소(HC) 및 디젤자동차에서의 입자상 물질(PM: Particulate Matter)등이 대기환경에 미치는 영향이 크므로 이러한 물질의 저감에 대한 요구가 점차 강화되어가고 있다. 특히, 디젤 엔진이 가솔린 엔진에 비해 대기오염의 주원인이라는 편견이 일반적으로 널리 알려져 있지만, 이는 눈에 보이는 Black smoke에 대한 거부반응이 있다는 점이다. 실제로 디젤 엔진의 유해 배출 성분 중에서 NOx는 가솔린과 비슷한 수준이나 HC와 CO성분은 상당히 적게 배출되고 있다. 또한, 디젤 엔진은 연료 경제성 및 지구 온난화의 원인인 CO$_{2}$ 배출이 적다는 장점이 있으므로 디젤 엔진에서 많이 배출되는 성분으로서 입자상 물질(PM) 및 NOx를 줄이는 방안이 요구되고 있다. 이를 저감시키는 방법은 여러가지가 있으나 분사계 측면에서 전자제어식 고압 연료 분사가 요구되고 있으며 이의 개발 필요성에 대해서 논하기로 한다.