• 한국자동차공학회논문집
• /
• 제9권1호
• /
• pp.63-74
• /
• 2001

In this study, a cycle simulation program of a Unit-Injection(UI) system was developed to estimate the injection performance of newly designed injection system. A fundamental theory of the simulation program is based on the conservation law of mass. Loss of fuel mass in the system due to leakage, compressibility effect of the liquid fuel and friction loss in the control volume was considered in the algorithm f the program. For the evaluation of the simulation program developed, the experimental result which was offered by the Technical Research Center of Doowon Precision Industry Co. was incorporated. Two main parameters; the maximum pressure in the plunger chamber and total fuel mass(kg) injected into the engine cylinder per cycle, were measured and compared with the simulation results. It was found that the maximum error rate of the simulation result to the experimental output was less than 3% in the rated rotational speed (rpm) range of the plunger cam.

• Journal of Advanced Marine Engineering and Technology
• /
• 제31권7호
• /
• pp.823-832
• /
• 2007

This paper presents the static characteristics of EGR-WI combined system. The water injection system was statically characterized by recording the engine exhaust outlet $NO_x$ emissions for comparison with baseline $NO_x$ emissions. Effects of the water injection system on CO and HC emissions and fuel consumption were examined. The research engine used for these experiments was a 103 kW turbocharged, intercooled, 2.5 L VM Motori CIDI engine equipped with a cooled EGR system. Water injection in the intake system demonstrated the potential for significant reductions in engine outlet $NO_x$ emissions. The system has reduced engine outlet $NO_x$ emissions by 40-50%, but caused significant increases in CO and HC emissions, particularly at low loads. Fuel consumption effects were minimal.

• 한국분무공학회지
• /
• 제8권4호
• /
• pp.17-23
• /
• 2003

To find suitable injection pressure, ultra high pressure impinging spray characteristics were investigated with a impinging distance and a impinging angle by using high pressure injection system. As impinging distance was increased, spray penetration was decreased but spray height was increased. For increase of injection pressure, spray penetration and spray height were increased until 2,500bar. But over this injection pressure region, the rate of increase was decreased suddenly.

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

• 한국자동차공학회논문집
• /
• 제20권1호
• /
• pp.39-45
• /
• 2012

In the standard CFD code, Lagrangian-Eulerian method is very popular to simulate the liquid spray penetrating into gaseous phase. Though this method can give a simple solution and low computational cost, it have been reported that the Lagrangian spray models have numerical grid dependency, resulting in serious numerical errors. Many researches have shown the grid dependency arise from two sources. The first is due to unaccurate prediction of the droplet-gas relative velocity, and the second is that the probability of binary droplet collision is dependent on the grid resolution. In order to solve the grid dependency problem, the improved spray models are implemented in the KIVA-3V code in this study. For reducing the errors in predicting the relative velocity, the momentum gain from the gaseous phase to liquid particles were resolved according to the gas-jet theory. In addition, the advanced algorithm of the droplet collision modeling which surmounts the grid dependency problem was applied. Then, in order to validate the improved spray model, the computation is compared to the experimental results. By simultaneously regarding the momentum coupling and the droplet collision modeling, successful reduction of the numerical grid dependency could be accomplished in the simulation of the high-pressure injection diesel spray.

• 에너지공학
• /
• 제13권2호
• /
• pp.118-127
• /
• 2004

본 연구는 배기량이 16.7ι인 V8형 터보차져 인터쿨러 직접분사식 디젤기관에서 흡기포트의 선회유동과 연료분사계 및 과급기가 기관성능 및 배출가스특성에 미치는 영향을 실험적으로 고찰하며 성능을 개선하는데 있다. 일반적으로 기관의 출력을 높이기 위하여 과급기 및 인터쿨러를 장착하여 과급공기를 냉각시켜 과급효율을 더욱 높인 TCI디젤기관이 보편화되고 있다 본 연구의 결과로서 흡기포트의 선회비가 2.25인 경우에서 압축비 17.5, re-entrant 8.5$^{\circ}$ 형 연소실, 노즐분공경 $\Phi$0.33*3+$\Phi$0.35*2, 노즐돌출량 3.18mm, 분사시기 BTDC 12$^{\circ}$CA, 과급기 T042(압축기 0.6A/R+46Trim, 터빈 1.0A/R+57Trim)경우가 기관성능 및 NO$_{x}$ 농도의 배출특성을 고려할 때 운전영역에서 가장 우수하여 흡기포트, 분사계 및 과급기에 대한 각 인자를 적정화할 수 있었다.

• 대한기계학회논문집B
• /
• 제24권3호
• /
• pp.390-401
• /
• 2000

In this study, numerical calculation is carried out to investigate the influence of injection timing, fuel amount, intake $O_2$ concentration, and EGR on Nitric Oxide(NO) formation using a two-zone model in a diesel engine. Results can be summarized as follows. The NO formation is very sensitive to the burned gas temperature, so multi-zone model must be applied to combustion process to predict the burned gas temperature exactly. Since the burned gas temperature increases rapidly during the premixed combustion, most NO is formed within 20 crank angle degrees after ignition. As the injection timing is retarded, the combustion occurs later in the expansion process which causes the decrease of burned gas temperature and, as a result, NO formation decrease. The increase of fuel amount results in the increase of earlier formation of NO in the engine. As the intake $O_2$ concentration increases, the maximum pressure and burned gas temperature increase due to activate combustion. And, [O] mole fraction of equilibrium combustion products also increase. Therefore NO exponentially increases. If exhaust gas is recirculated, the burned gas temperature decreases which results in NO decrease. If exhaust gas is cooled, more NO can be decreased.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
• /
• pp.220.2-220.2
• /
• 2011

Biodiesel and biodiesel blend fuel are receiving increasing attention as alternative fuels for diesel engines without substantial modifications. Biodiesel fuels and blending have been widely studied and applied in diesel engine because of biodiesel's lower sulfur, lower aromatic hydrocarbon and higher oxygen content. Biodiesels have the potential to be oxidized in different condition. It has reported that oxidation deterioration of biodiesel is different in the condition of storage and oxidation causes chemical property change of methyl esters. Sunlight intensity, temperature, material of container and contact surface with oxygen are key dominant factors accelerating oxidation deterioration. In this study, we chose temperature among key oxidation conditions and metal container filled with biodiesel was heated at about $110^{\circ}C$ for 10 days in order to accelerate oxidation deterioration. To better understand the effect of biodiesel blends on emission, steady state tests were conducted on a heavy duty diesel engine. The engine was fueled with Ultra Low Sulphur Diesel(ULSD), a blend of 10% and 20%(BD10, BD20) on volumetric basis, equipped with a common rail direct injection system and turbocharger, lives up to the requirements of EURO 3. The experimental results show that the blend fuel of normal biodiesel with BD10 and BD20 increased NOx. The result of PM was similar to diesel fuel on BD10, but the result of PM on BD20 was increased about 63% more than its of diesel. The blend fuel of Oxidation biodiesel with BD10 and BD20 increased NOx as the results of normal biodiesel. But PM was all increased on BD10 and BD20. Especially THC was extremely increased when test fuel contains biodiesel about 140% more than its of diesel. Through this study, we knew that oxidation deterioration of biodiesel affects emission of diesel engine.

• 한국자동차공학회논문집
• /
• 제19권5호
• /
• pp.118-124
• /
• 2011

To reach the Euro-6 regulations of PM and $NO_x$ for light-duty diesel vehicles, it will be necessary to apply the CDPF and the de-$NO_x$ catalyst. The described system consists of a catalytic configuration, where the CDPF is placed downstream of the diesel engine and followed by a urea injection unit and a urea-SCR catalyst. One of the advantages of this system configuration is that, in this way, the SCR catalyst is protected from PM, and both white PM and deposits become reduced. In the urea-SCR system, the injection control of reductant is the most important thing in order to have good performance of $NO_x$ reduction. The ideal ratio of $NH_3$ molecules to $NO_x$ molecules is 1:1 based on $NH_3$ consumption and having $NH_3$ available for reaction of all of the exhaust $NO_x$. However, under the too low and too high temperature condition, the $NO_x$ reduction efficiency become slower, due to temperature window of SCR catalyst. And space velocity also affects to $NO_x$ conversion efficiency. In this paper, rig-tests were performed to evaluate the effects of $NO_x$ and $NH_3$ concentrations, gas temperature and space velocity on the $NO_x$ conversion efficiency of the urea-SCR system. And vehicle test was performed to verify control strategy of reductatnt injection. The developed control strategy of reductant injection was improved over all $NO_x$ reduction efficiency and $NH_3$ consumption in urea-SCR system. Results of this paper contribute to develop urea-SCR system for light-duty vehicles to meet Euro-5 emission regulations.

• 한국분무공학회지
• /
• 제24권3호
• /
• pp.114-121
• /
• 2019

The effect of injector driving current pattern on fuel injection rate of solenoid diesel common rail injector was studied by computer simulation. The time resolved fuel injection rate and injected quantity per stroke of a common rail injector driven with the five current patterns were computer simulated. The fuel injection rate and injected quantity per stroke according to the rail pressure and fuel injection period were also computer simulated. When the common rail injector was driven with the five driving current patterns of peak & hold, there was no difference in the fuel injection rate in the peak section regardless of all the current patterns of the five cases. On the other hand, the magnitude of the hold current value influenced the injection rate and injected quantity per stroke. That is, in the current pattern of three cases where the hold current value is equal to or more than a constant value of the peak current value, the fuel injection rates for the given common rail rail pressure and injection period are same one another. On the other hand, the current pattern of the two cases, in which the hold current value is smaller than a certain value, there is a large fluctuation in the fuel injection rate.