• 대한기계학회논문집B
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• 제30권7호
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• pp.682-691
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• 2006

This study was conducted to assess the effect of mixed fuel composition and mass fraction on spray inner structure in evaporating transient spray under the various ambient conditions. Spray structure and spatial distribution of liquid phase concentration are investigated using a thin laser sheet illumination technique on the multi-component mixed fuels. A pulsed Ar+ laser was used as a light source. The experiments were conducted in a constant volume vessel with optical access. Fuel was injected into the vessel with electronically controlled common rail injector. Used fuel contain $i-octane(C_8H_{18}),\;n-dodecane(C_{12}H_{26})$ and $n-hexadecane(C_{16}H_{34})$ that are selected as low-, middle- and high-boiling point fuel, respectively. Experimental conditions are 25Mpa, 42MPa, 72MPa and 112MPa in injection pressure, $5kg/m^3,\;15kg/m^3\;and\;20kg/m^3$ in ambient gas density, 400K, 500K, 600K and 700K in ambient gas temperature, 300K and 368K in fuel temperature, and different fuel mass fraction. Experimental results indicate that the more high-boiling point component, the longer the liquid phase it were closely related to fuel physical properties, but injection pressure had no effect on. And there was a high correlation between the liquid phase length and boiling temperature at 75% distillation point.

• 한국자동차공학회논문집
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• 제18권3호
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• pp.80-87
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• 2010

The purpose of this paper is to analyze the effects of ethanol blending ratio and fuel temperature in diesel-ethanol blended fuel on the spray-atomization characteristics in a high pressure common-rail injection system. In this work, a diesel fuel and three blended fuels were used as test fuels. Blended fuels were made by blending ethanol with a purity 99.9% to diesel fuel, from 0% to 30%. In order to keep diesel-ethanol blending stability, 5% of biodiesel fuel as volumetric ratio was added into test fuels. The fuel temperature was controled in steps with 40K, from 290K to 370K. Macroscopic spray characteristics were investigated by analyzing the spray tip penetration and spray cone angle through spray images obtained from visualization system. In addition, in order to study microscopic spray characteristics of ethanol blended fuels, the droplet diameter, was analyzed using the droplet measuring system. It is revealed that the spray tip penetration is similar regardless of ethanol blending ratio. As ethanol blending ratio is increased, the spray cone angle becomes wider. It is shown that the spray cone angle is affected by low viscosity and density of ethanol. As the fuel temperature increases, the spray tip penetration and spray cone angle become shorter and narrower respectively. The SMD of ethanol blending fuels is smaller than that of diesel fuel because of low viscosity and surface tension of ethanol.

• 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.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.76-84
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• 2010

The aim of this study is to analyze the effect of the ethanol blending in diesel-ethanol blended fuels on the spray and combustion characteristics in a common-rail four-cylinder diesel engine. For the analysis of the spray characteristics, the spray images were obtained using a high speed camera with metal-halide lamps. From these spray images, the macroscopic spray characteristics such as the spray tip penetration and spray cone angle were investigated. Also, the combustion characteristics including the combustion pressure and the rate of heat release were studied with the analysis of the exhaust emissions in diesel-ethanol blended fuel driven diesel engine. It can be confirmed from the experiment on spray characteristics of diesel-ethanol blended fuels that the increased ethanol blending ratio induced the decrease of the spray tip penetration after the end of the injection. The spray cone angle slightly increased by the blending of ethanol fuel. In the experiment on atomization characteristics, the ethanol blending caused the improvement of the diesel atomization performance. On the other hand, at the same engine load condition, the increase of the ethanol blending ratio lead to lengthen the ignition delays, and to decrease the peak combustion pressure and the rate of heat release. Totally, the combustion and emission characteristics of ULSD and DE10 showed similar characteristics. However, in the case of DE20, CO and HC rapidly increased, and $NO_x$ decreased. It can be believed that 20% ethanol disturbed the combustion of diesel-ethanol blended fuel due to the low cetane number and evaporation.

• Tribology and Lubricants
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• 제33권1호
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• pp.23-30
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• 2017

The electric controlled marine diesel engine has fuel pump generating the high pressurized fuel for fuel injection to combustion chamber via a common rail. Fuel pump consists of a cam-roller system. Journal bearing installed between a roller and a cam-roller pin is subjected to fluctuating heavy and instant loads by cam lift. First, Kinematic analysis is carried out to predict bearing loads during one cycle acting on the journal bearing. Second, flexible multi-body dynamic analysis and transient elasto-hydrodynamic(EHD) lubrication analysis for journal bearing considering elastic deformation of cam-roller pin, roller and bearing are conducted using AVL EXCITE/PU software to predict lubrication performance. The clearance ratio and journal groove shape providing lubrication oil are important parameter in bearing design having good performance and can be changed easier than other design parameters such as diameter, width, oil supply pressure and bearing material grade. Generally, journal bearing performance is represented by the minimum oil film thickness(MOFT) and peak oil film pressure(POFP). As well as the traditional design parameters(MOFT, POFP), in this study, temperature rise of lubrication oil is also evaluated through the side leakage flow of supplied oil. By the evaluating MOFT, POFP and temperature rise, the optimum bearing clearance ratio is decided.

• 한국분무공학회지
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• 제25권1호
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• pp.21-26
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• 2020

The objective of this work is to numerically reveal the effect of equivalence ratio change on the simultaneous reduction of NO_X and soot emissions from the simulated-EGR compression ignition engine containing CO₂. An experiment was conducted by using a single-cylinder common-rail injection system engine, an intake control system, and exhaust emissions analyzers. The numerical analysis results were validated under the same experimental conditions. To investigate the effect of equivalence ratio by simulated-EGR containing CO₂, the O₂, N₂, and CO₂ mole fraction were changed in the initial air conditions to the cylinder. The results were analyzed in terms of peak cylinder pressure, indicated mean effective pressure, indicated specific nitrogen oxide, and indicated specific soot. It was revealed that ignition delay characteristics and heat release rate (ROHR) characteristics were not significantly different according to the equivalence ratio. However, as the equivalence ratio increased from 0.68 to 0.83, the maximum combustion pressure and IMEP decreased by about 6.5% and 9.4%, respectively. In the case of ISFC, as is well known, the trend is opposite of IMEP. In the case of ISNO, as the equivalence ratio increased, less NO was generated, and as the equivalence ratio increased by 0.05, the ISSoot value of about 10% increased.

• 전기전자학회논문지
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• 제18권1호
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• pp.152-158
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• 2014

본 연구에서는 저온유동성 성능검사 시스템 구현을 통해 디젤 차량용 통합형 연료히터의 성능을 평가한다. 저온 유동성 시험장치에서 $+20{\sim}-30^{\circ}C$ 온도범위에 따라 분리형과 통합형 연료히터 성능을 비교하고, 필터 전후에 따라 유압과 시동시간, 히터의 소모전력을 측정한다. 이때 다양한 종류의 필터면적을 사용함으로써 통합형 연료히터와 분리형을 비교한 결과 시동 시간이 23% 향상되었고, 저온시동성능은 19% 정도 향상된다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권1호
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• pp.8-12
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• 2015

비에스테르화 바이오 디젤유는 에스테르화 공정을 거치지 않기 때문에 공정에 드는 비용이 절감되며 경유에 5%로 혼합하여 전자제어 분사식 디젤엔진에 사용할 경우 에스테르화 바이오 디젤유보다 경유에 더 유사한 성능을 나타내었다. 이러한 연구를 바탕으로 경유에 5% 혼합된 비에스테르화 바이오 디젤유를 전자제어 분사식 디젤엔진에 적용하기 위해서는 성능 최적화가 필요하다. 본 연구에서는 비에스테르화 바이오 디젤유의 성능 최적화를 위한 기초 실험으로 연료소비율, 질소산화물 및 도시평균유효압력을 반응치로 정하고 제어 가능한 6가지 인자에 대해서 그 영향력을 평가하고자 부분요인배치법을 이용하여 25%와 50%의 부분 부하에서 실험을 수행하였다. 그 결과 6가지 인자 중 분사시기 및 커먼레일압력이 가장 큰 영향을 미쳤고 각 부하에서 영향의 크기는 다르게 나타났다.

• 대한기계학회논문집B
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• 제36권7호
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• pp.745-752
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• 2012

디젤엔진은 바이오연료 적용을 위한 엔진으로서 가솔린엔진과 비교해 사용연료가 바이오연료와 유사한 높은 세탄가를 가지며, 가솔린엔진과 달리 점화계통 장치의 불필요 등 기존 엔진의 개조비용 등에서 유리한 장점이 있다. 따라서 본 연구에서는 상용 디젤 엔진의 커먼레일 분사시스템을 사용하여 바이오연료인 식물성 팜유의 분무거동특성을 해석하고, 그 결과를 기존의 디젤엔진 연료인 경유와 비교 분석하였다. 실험변수로서는 분사압력과 경유에 대한 바이오디젤 연료의 혼합비율(BD3, BD5, BD20, BD30, BD50, BD100)을 달리하였다. 분사압력은 500bar, 1000bar, 1500bar 및 1600bar로 설정하고 분사기간은 $500{\mu}s$로 동일하게 하였다. 본 연구의 결과로서, 분사압력이 동일한 경우 사용한 바이오디젤 연료의 혼합비 변화에 대한 거시적 분무거동특성(분무선단도달거리 및 분무각)의 변화는 뚜렷하지 않았다. 특히 분무각의 경우 본 연구의 모든 실험조건에 있어서 약 $15^{\circ}$의 값을 나타내었다.

• 한국수소및신에너지학회논문집
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• 제25권5호
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• pp.533-540
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• 2014

The remanufacturing industry for automotive parts is a major issue which affects the environment protection and CO2 reduction throughout the world. Beside this, remanufacturing technologies of worn-out diesel engines have been developing to make as close to new as possible. In this study, the characteristics of the engine-power output and exhaust emissions of remanufactured diesel engine by hydrogen enrichment are evaluated by measuring the engine and vehicle test. Moreover, with worn-out diesel engine and first generation common-rail engine, we compared by testing their characteristics, resulting in the restoration of engine-power output more than 93%, as well as marvelously reduces the THC and NOx emission. At a guess, high pressure injection of diesel increases fuel atomization characteristics with excellence combustion efficiency, resulting in reduction of THC emission. Also, rapid cooling of EGR decreases combustion temperature, resulting in reduction of NOx emission. Consequently, these remanufacturing for diesel engine enables worn-out diesel engine to have restoration to the original state. Simultaneously achieved 2 goals called that CO2 emission reduction and protection of environment by remanufacturing engine.