• 한국분무공학회지
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• 제17권2호
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• pp.71-76
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• 2012

The aim of this work was to investigate the combustion and nanoparticle emission characteristics of premixed charge compression ignition (PCCI) combustion at various test conditions using a single cylinder common-rail diesel engine. In order to create the homogeneity of fuel-air mixture, the premixed fuel (gasoline) was injected into premixing chamber during the intake process and then the diesel fuel was directly injected into the combustion chamber as an ignition source for the gasoline premixture. From these results, it revealed that the ignition delays and combustion durations were gradually prolonged and the peak combustion pressure were increased because diesel fuel was injected early injection timing with the increase of premixed ratio. In addition, as the increase of premixed ratio, total particle number is generally decreased and particle volume also indicated low levels at the direct injection timing from BTDC $20^{\circ}$ to TDC. At further advanced injection timing, total particle number and volume were generally increased

• 한국자동차공학회논문집
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• 제15권5호
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• pp.78-85
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• 2007

Recently, diesel vehicles have been increased and their emission standards have been getting strict. The emission of diesel vehicles contains numerous dangerous compounds, especially particulate matters cause a serious environmental pollutant and affect to human health seriously. Thousands of studies have already reported that particulate matters are associated with respiratory and cardiovascular diseases, and death. Due to these, it is necessary to measure the soot concentration and soot particle size in laboratory flames or practical engines to recognize the soot formation, and develop the control strategies for soot emission. In this study, the characteristics of exhausted soot particle size and volume fraction from 2.0L CRDI diesel engine have been investigated as varying engine speed and load. Laser induced incandescence has been used to measure soot concentration. Time-resolved laser induced incandescence has been used to determine soot particle size in the engine. The soot volume fraction is increased as increasing engine load but soot volume fraction is decreased as increasing engine speed. The primary particle size is distributed about $35nm{\sim}60nm$ at each experimental conditions.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.1677-1683
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• 2015

배출가스 규제강화에 대응하기 위해 전자제어 디젤엔진의 적용으로 연료 분사량과 연료 분사시기를 정밀하게 제어하여 연료소비율과 출력 향상 및 소음과 진동이 감소되었다. 전자제어 디젤엔진 시스템의 성능을 유지하기 위해서는 연료압력을 정밀하게 제어하는 중요한 부품이 연료압력 레귤레이터이며 제어불량이 발생할 경우 연료압력이 정밀하게 제어되지 않아 시동불량, 시동지연, 가속불량, 엔진부조 등 이상 현상이 초래된다. 본 실험에서는 연료압력 레귤레이터의 고장에 따른 성능변화를 고찰하기 위하여 연료압력 레귤레이터 제어율에 변화를 주어 연료압력, 회수된 연료유량과 엔진회전수에 미치는 영향을 실험적으로 고찰하였다. 실험결과, 연료압력 레귤레이터의 제어율이 기준에서 4-6% 정도 낮아지면 엔진회전수, 회수되는 연료유량의 변화가 크게 나타났으며 이 때 이상현상이 발생함을 확인하였다. 또한 이를 통하여 연료압력 레귤레이터의 고장 유무을 판단할 수 있다.

• 한국자동차공학회논문집
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• 제17권1호
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• pp.105-113
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• 2009

The performance of a direct-injection type diesel engine often depends on the strength of swirl or squish, shape of combustion chamber, the number of nozzle holes, etc. This is of course because the combustion in the cylinder was affected by the mixture formation process. In this paper, combustion process of biodiesel fuel was studied by employing the piston which has several grooves with inclined plane on the piston crown to generate swirl during the compression stroke in the cylinder in order to improve the atomization of high viscosity fuel such as biodiesel fuel and toroidal type piston generally used in high speed diesel engine. To take a photograph of flame, single cylinder, four stroke diesel engine was remodeled into two stroke visible engine and high speed video camera was used. The results obtained are summarized as follows; (1) In the case of toroidal piston, when biodiesel fuel was supplied to plunger type injection system which has very low injection pressure as compared with common-rail injection system, the flame propagation speed was slowed and the maximum combustion pressure became lower. These phenomena became further aggravated as the fuel viscosity gets higher. (2) In the case of swirl groove piston, early stage of combustion such as rapid ignition timing and flame propagation was activated by intensifying the air flow in the cylinder. (3) Combustion process of biodiesel fuel was improved by the reason mentioned in paragraph (2) above. Consequently, the swirl grooves would also function to improve the combustion of high viscosity fuel.

• 전기전자학회논문지
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• 제20권2호
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• pp.200-204
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• 2016

본 연구에서는 유로형(EURO type) 클린 디젤 CRDI(common rail direct injection) 엔진용 오버플로우 밸브 성능 평가 시스템을 구현한다. 친환경 조건에 맞도록 정밀 기능을 구비한 오버플로우를 위해 스프링의 하중을 고려한 구현이 중요하다. 특히 정밀제어에 따른 디젤 차량의 성능평가는 연비 향상과 환경 규제 만족이 필연적이다. 이에 성능평가를 위한 평가 알고리즘의 기본 조건은 100cc 미만에서 3.0 bar, 150 cc 이상에서 3.3 bar, 250 cc이상에서 4.0 bar를 사용하여 시험한다.

• 한국자동차공학회논문집
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• 제21권1호
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• pp.99-106
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• 2013

DME (Di-Methyl Ether) is synthetic product that is produced through dehydration of methanol or a direct synthesis from syngas. And it is able to save fossil fuel and reduce pollutants of emission such as PM and $CO_2$. In spite of its advantages it is difficult to design DME fuelled engine system because DME fuel may cause to severely generate cavitation and corrosion in fuel delivery system due to physical properties of DME. Therefore, in this study three-dimensional internal flow characteristics with consideration of cavitation were predicted in the DME injector using diesel and DME fuel. Moving grid technique was employed to describe needle motion and 1-D hydraulic simulation of injector was also simulated to obtain transient needle motion profiles. The results of simulation show that cavitations was generated at the inlet of nozzle near high velocity region both diesel and DME. And mass flow rate of DME is reduced by 4.73% compared to that of diesel at maximum valve lift because cavitation region of DME is much more larger. To increase flow rate of DME injector, internal flow simulation has been conducted to investigate the nozzle hole inner R-cut effect. The flow rates of diesel and DME increase as R-cut increases, and flow coefficient of DME fuel injector was increased by 6.3% on average compared with diesel fuelled injector. Finally, optimum shape of DME injector nozzle is suggested through the comparison of flow coefficient with variation of nozzle hole inner R-cut.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.301-310
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• 2003

Eco-Machinery engineering technologies in KIMM for reducing NOx emission were introduced. Combustion technologies such as reburning and fuel staged or air staged combustion have been applied to reduce NOx emission in the field of boiler furnaces. Lean premixed combustion method have been studied in gas turbine combustor. Hybrid system with plasma and SCR being considered as prospective method of De-NOx has been developed. Also, low NOx technologies including common rail system, EGR and DPF in diesel engine have been investigated.

• 한국연소학회지
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• 제15권1호
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• pp.1-11
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• 2010

In this study, the coupled simulation of fuel injection model and three-dimensional KIVA-3V code was tried to develop an algorism for predicting the effects of varying fuel injection parameter on the characteristics of fuel injection and emissions. The numerical simulations were performed using STAR-CD code in order to calculate the intake air flow, and the combustion characteristics is examined by KIVA-3V code linked with the conditional moment closure(CMC) model to predict mean turbulent reaction rate. Parametric investigation with respect to twelve relevant injection parameters shows that appropriate modification of control chamber orifice diameter, needle valve spring constant and nozzle chamber orifice diameter can significantly reduce NOx and soot emissions. Consequently, it is needed to optimize the fuel injection system to reduce the specific emissions such as NOx and soot.

• 동력기계공학회지
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• 제17권6호
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• pp.149-155
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• 2013

Since bio-diesel oil has a merit that it satisfies both demand of substitution for fossil fuel and reduction in carbon dioxide emission, it is widely used in diesel engines by blending in gas oil in small quantity. It is needed to reduce in NOx emission in some way or others if blending ratio of bio-diesel oil is going to increase, because it is demerit that bio-diesel oil emits more NOx emission than gas oil. In this study, it was accomplished to optimize 3 factors what effect on NOx emission as blending ratio of bio-diesel oil, injection timing and common rail pressure with an introduction of a design of experiments, in order to minimize a number of tests. It was cleared that to introduce the design of experiments was very available in NOx optimization.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.2076-2081
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• 2004

Future exhaust gas limits for diesel-driven passenger cars will force the automotive industry to significantly improve the performance of engine. Since modern common-rail injection systems deliver more degrees of freedom referring to the injection process, again the optimization of the injection process could offer a possibility to meet the exhaust gas limits. This study describes the characteristic the pilot spray structure of piezo-driven injector for a passenger car common-rail system to be applicable multiple injection caused by fast response rather than solenoid-driven injector. The piezo-driven injector is prototype injector with same needle chamber of solenoid injector and the solenoid-driven one is commercial injector. The pilot spray characteristic such as spray tip penetration, spray speed, spray angle were obtained by spray images, which is measured by the Mie scattering method with optical system for high-speed temporal photography. It was found that piezo-driven injector effected electric change as important factor and showed faster response than solenoid-driven injector.