• 한국분무공학회지
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• 제7권1호
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• pp.7-13
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• 2002

This paper is study on simultaneous reduction of NOx and soot for direct injection diesel engine using high and low cetane fuels. The stratified injection system was applied for diesel engine to use high and low cetane fuel. In this study, diesel fuel was used as high cetane fuels, methanol was used as low cetane fuels. Some parts of the injection system, ie. Nozzle holder. delivery vale, was remodeled to inject dual fuel sequentially from one injector. The leak injection quantity ratio of dual fuel was certificated by volumetric ratio at injection quantity experiment. According as concentration of low cetane fuel was varied, combustion experiment was performed using Toroidal and Complex chamber. Also, exhaust gas and fuel consumption were measured at the same time. Simultaneous reduction of NOx and soot was achieved at complex chamber regardless of concentration of low cetane fuel. However, according as concentration of low cetane fuel was increased, THC and CO was increased.

• 한국자동차공학회논문집
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• 제19권3호
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• pp.99-105
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• 2011

This paper described the effect of the multiple injections on the emission characteristics and combustion stability in a common rail diesel engine. In order to investigate the influence of multiple injections in a passenger car diesel engine, the injection strategy was varied with pilot injection, post injection and one main injection at various conditions. Based on the experimental results, the combustion and emissions characteristics were analyzed for the various injection strategies such as main, pilot-main, double-pilot-main, double- pilot-main-post injection strategy. It is revealed that the $NO_X$, HC and CO emissions are reduced by double pilot and post injection at medium load, however, soot emission is increased. Also, in the case of multiple injection, the combustion pressure is increased smoothly near the TDC and the coefficient of variation and fuel consumptions are decreased.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.134-134
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• 2010

Recently, the interest of the study about IGCC(Integrated Gasification Combined Cycle), one of New & Renewable Energy technologies, bas been increased due to the United Nations Framework Convention on Climate Change, the Low Carbon Green Growth policy, etc. Also, with this interest of IGCC, the study on the gas turbine utilizing the synthetic gas is performing actively. In the study of the gas turbine characteristic, the power performance and the combustion efficiency are mainly discussed and also the concern about the exhaust gas is being taken care of due to the increasing awareness of the environment. With this, we would like to go over the exhaust gas emission characteristic by the synthetic gas inflow in this test. In order to conduct such a test, we constructed a synthetic gas supplying system to supply the synthetic gases ($H_2$: hydrogen, $N_2$: nitrogen, CO: carbon monoxide, $CO_2$: carbon dioxide, and $H_2O$: steam) quantitatively and this combustion test was conducted by controlling the supplied synthetic gases artificially. The concentration of the exhaust gases appeared variously depending on the differences of the inflow nitrogen amount and the steam amount, whether or not the carbon dioxide flow in and so on. The results of the test can be able to be utilized for the IGCC study by understanding the exhaust gas emission characteristic of the coal gas turbine by synthetic gas composition.

• 한국자동차공학회논문집
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• 제14권4호
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• pp.84-91
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• 2006

In this study, the effect of EGR and fuel injection pressure on the characteristics of combustion and emission performance of the common-rail diesel engine is investigated using DME fuel as a smoke-free alternative fuel. Because the heating value and density of DME fuel are lower than those of diesel fuel, the injection duration of the DME engine is relatively longer than the injection duration of the diesel engine with the same injection pressure. However, the higher injection pressure can shorten the injection duration for the DME engine. Although the smoke level of the DME engine is much lower than that of the diesel engine, the NOx is at a level similar to that of the diesel engine. As a proposed solution for this, the EGR technique is empirically applied to the DME engine. In the experiments, the injection pressure was changed from 200bar to 400bar, and the EGR rate was limited under 40%. With the same injection timing and fuel amount, the experiment results indicated that the increase of injection pressure led to the increase of IMEP while decreasing HC and CO emissions. However, the NOx emission tends to increase as the injection pressure becomes higher. On the other hand, as the EGR rate was increased, NOx emission and A/F were reduced while the HC and CO emissions were increased. Because HC and CO emissions have the critical A/F point where the emissions of HC and CO are rapidly increased, it is proposed that the EGR rate must be limited under the critical EGR rate.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.130-136
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• 2011

This study describes the effect of EGR rate on the combustion and emissions characteristics of a four cylinder CRDI diesel engine using biodiesel (soybean oil) blended diesel fuel. The test fuel is composed of 30% biodiesel and 70% ULSD (ultra low sulfur diesel) by volumetric ratio. The experiment of engine emissions and performance characteristics were performed under the various EGR rates. The experimental results showed that ignition delay was extended, the maximum combustion pressure and heat release gradually were decreased with increasing EGR rate. Comparing biodiesel blended fuel to ULSD, the injection quantity of biodiesel blended fuel was further increased than ULSD. The emission results showed that $NO_x$ emission of biodiesel blended fuel becomes higher according to the increase of EGR rate. However, in the case of biodiesel blended fuel, HC, CO and soot emissions were decreased compared to ULSD.

• 동력기계공학회지
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• 제10권3호
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• pp.5-10
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• 2006

In a conventional and lean operating engine, the state of mixture is very important in the combustion and emission characteristics. Lean operation is known to decrease the formation while maintaining a good fuel economy, but the unstable operation due to misfire and erratic combustion prevents engines from being operated at very lean mixtures, so both combustion rates and exhaust emission formation need to be satisfied comparably. In this study, it is designed and experimented the modified engine, and analyzed the combustion and exhaust emission according to the change of engine speed and with adding ozone. The conclusions were drawn out and enumerated as follows. 1. At the experimental result of automobile diesel engine, it has been verified that the formation of particulate matter(PM) gas is able to be lower with the addition of optimum quantities of ozone. 2. Carbon monoxide(CO) was formed by the lack of oxygen and the thermal dissociation in the combustion process. Therefore, with the change of swirl valve's position and addition of oxygen and ozone, CO formation was decreased by the increasing of excessive O2, but it was increased by the temperature of combustion gas growing higher. As a result of the two effects, CO formation was decreased in this study. 3. Hydrocarbon(HC) was formed by the lack of O2, and the flow of mixture in cylinder. According to opening of the swirl valve and adding the oxygen and ozone, hydrocarbon gas was decreased by 20%, 9%, and 27.5%, respectively. 4. Nitric oxides($NO_x$) was strongly affected by the combustion gas temperature. As a result of respectively experimental conditions, $NO_x$ formation was increased about 20% due to (be the) high(er) combustion gas temperature.

• 대한기계학회논문집B
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• 제38권6호
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• pp.501-511
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• 2014

바이오매스 원료로부터 급속열분해 반응을 통하여 생산되는 바이오 오일은 화석연료를 대체할 수 있는 잠재력을 가지고 있다. 하지만, 바이오 오일은 에너지 밀도와 세탄가가 낮고 점성도가 높은 연료의 한계성이 있으므로 디젤엔진에 적용하기에는 제한적이다. 따라서, 안정적인 연소를 얻기 위해서는 바이오 오일을 세탄가가 높은 연료와 유화하거나 혼합하여 사용하여야 한다. 하지만 바이오 오일과 화석연료는 극성이 달라서 서로 혼합되지 않으며 가장 손쉽게 혼합되는 연료는 알코올계 연료이다. 본 연구에서는 바이오 오일의 연료특성을 향상시키기 위하여 에탄올 연료와 혼합하였으며, 연료의 자발화 특성을 향상시키기 위하여 세탄가 향상제인 PEG 400, 2-EHN 도 첨가하였다. 또한 최대 15%의 바이오 오일이 혼합된 혼합연료를 디젤엔진에서 안정적으로 연소시키기 위하여 고압축비 피스톤도 적용하였다.

• 한국산학기술학회논문지
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• 제18권5호
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• pp.420-427
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• 2017

최근 화석연료의 고갈, 지구온난화 그리고 환경오염이 세계적인 공공의 문제로 대두됨으로써 신재생에너지에 관한 연구들이 많이 진행되고 있다. 이러한 신재생에너지들 중 바이오연료는 다루기 쉬울 뿐만 아니라, 낮은 가격과 풍부한 자원성이 미래에 화석연료를 대체할 수 있는 잠재성을 가지고 있다. 바이오연료 중 본 연구에서 사용한 급속 열분해유는 폐목재나 억새, 갈대와 같은 비식용작물에서부터 추출되었고, 이는 무한한 자원성 때문에 디젤엔진에서 디젤유를 대체할 신재생에너지로 주목받고 있다. 하지만 열분해유는 낮은 세탄가, 높은 점도, 높은 산도 그리고 낮은 발열량으로 인해 디젤엔진에 직접적으로 적용하기가 어렵다. 따라서 이러한 낮은 물질적 특성을 개선하기 위해서 본 연구에서는 에탄올과 같은 알코올계 연료와 혼합하여 투입하였다. 알코올계 연료인 에탄올이 열분해유의 저장 및 보관성에도 도움을 줄뿐 아니라 점도를 낮춰주어 엔진에 적용하기 수월하게 만들기 때문이다. 열분해유-에탄올 혼합연료를 파일럿 분사한 디젤유 이후 분사하여 연소시켜 이때의 연소 및 배기특성에 대해 고찰해 보았고, 그 결과로 미연탄화수소와 일산화탄소는 증가하는 경향을 띄지만 NOx와 PM이 현저히 줄어든 결과를 확인할 수 있었다.

• 한국산학기술학회논문지
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• 제19권3호
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• pp.112-118
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• 2018

화석연료를 기반으로 하는 내연기관의 엄격한 배기가스규제를 충족시키기 위해 자동차와 선박용 후처리장치의 비중이 점차로 증가하고 있다. 디젤엔진은 $CO_2$ 배출량이 적고 강력한 파워와 연료의 경제성을 가지고 있으며, 상용차뿐만 아니라 승용차에서도 시장의 수요가 증가하고 있다. 디젤 연료 특성으로 인하여 질소산화물은 국부적인 고온연소 영역에서 생성되며, 입자상물질은 확산연소 영역에서 생성이 된다. LNT와 urea-SCR 촉매는 디젤엔진에서 NOx를 저감시키기 위한 후처리장치로 개발되어져왔다. 이 연구는 가혹해지고 있는 배기가스 규제 대응을 위해 소형과 중 대형 디젤기관에 많이 사용되고 있는 Cu SCR 촉매의 NOx 저감 성능 향상을 목적으로 한다. $5Cu-2ZrO_2$/Zeolyst(Si/Al=13.7)SCR 촉매는 $5Cu-2ZrO_2$/93Zeolite(Si/Al=2.9) 촉매에 비해 촉매온도 $300^{\circ}C$ 이상에서 약 5-50% 수준으로 de-NOx 성능이 높았다. Zeolite는 zeolyst에 비해 금속의 분산도가 낮고 평균 입경이 커짐에 따라 촉매의 반응속도가 저하되었다. 10wt% Cu가 담지된 $10Cu-2ZrO_2$/88Zeolyst 촉매는 $200^{\circ}C$에서 40%, $350^{\circ}C$에서 약 65%로 NOx 정화성능이 가장 높았고, Cu의 이온이 제올라이트의 결정화합물인 Al과의 이온교환율이 증가함에 따라 다른 촉매에 비해 20-40% de-NOx 성능이 향상되었다.

• 유기물자원화
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• 제15권3호
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• pp.106-112
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• 2007

본 연구는 하수슬러지 케이크와 타르, 피트모스를 혼합하여 연료 및 보조연료로써 활용이 기능하도록 안정된 발열랑을 가지는 혼합비를 도출하고, 제조된 고형연료의 연소특성과 대체연료로써의 RDF의 적용가능성을 확인하는데 목적이 있다. 각각의 개별 발열량은 하수슬러지 케이크와 피트모스가 4000~4500kcal/kg 비슷하였으며, 타르의 발열량은 7000kcal/kg로 가장 높은 것으로 나타났다. 또한, 발열량 6,000kcal/kg 이상으로 하는 적정 혼합비를 (하수슬러지케이크 : 타르 : 피트모스) 1 : 4 : 1에서 1: 7 : 1까지로 하여 길이 1.6cm, 직경 1.3cm, 중량 2.3g의 고형연료를 제조하였다. 제조된 고형연료의 RDF 적용가능성 분석결과, 배기가스 분석에서는 혼합비에 따라 발생되는 배기가스의 성분농도가 크게 변하지 않았으며, 고형연료의 불꽃 지속시간은 5분 내외로 동일 질량 2.3g을 연소시킨 일반 무연탄과 지속시간이 비슷한 것으로 나타났다. 따라서 본 연구에서 제조한 고형연료의 연료 및 보조연료로서의 활용이 기능할 것으로 판단된다.