Diesel engines have been widely used in heavy duty vehicles due to their superior fuel economy and high power density. However, they have a relatively high level of NOx and soot emissions. With the increasingly stringent emission standards the main focus of engine research is to simultaneously reduce the fuel consumption and emission. This paper is applied to three-dimensional simulation of in-cylinder phenomena of a direct injection diesel engine for solving the above problem. Ignition used auto ignition model and diffusion burning is modeled by the eddy dissipation model of Magnussen-Hjertager. The results show temperature, pressure, NOx, Soot, fuel concentration distribution which is diesel engine major parameter

디젤 엔진의 내부 연소 특성에 따른 수치 해석적 연구

To investigate the combustion characteristics of RI-CNG engine, a series of experiments have been carried out. Test fuel of CNG was directly injected into a sub-chamber with a GDI injector and the exact quantities of the fuel and also air were measured with precision flow-meters. The test RI-CNG engine was operated under light load. Equal quantities of CNG were injected in every cycle regardless of experimental conditions such as different CNG injection timings and air quantities. In this study, combustion characteristics like P max , Θ Pmax , COV imep have been obtained under the injection timings change from EVC (exhaust valve closure) to limit injection (engine operates unsteadily). When the injection timing is AETDC 120°, the RI-CNG engine shows advanced Θ pmax . And P max gradually increases when the injection timing is retarded from AETEC 120° to 180°. Because the RI-CNG engine can obtain fast combustion velocity by optimal mixing states and optimal injection timing, the engine shows high operation stability in spite of the excess air ratio changing from λ= 1.0 to λ= 1.4.

Light load combustion characteristics of RI-CNG engine

Currently, we need to produce environmentally friendly vehicles. One of Environmentally friendly vehicles is LPG car and this study is about performance of the LPLi fuel pump. The fluid rate in a direct-injection LPG fuel pump is analysis using a LPi Pump Test Bench. The analsis accounts for fully coupled fluid-structure interactions, the effects of movement and its the inlet/outlet valves and the fluid. The flow rate and the pressure of the fuel pump under various pump speeds and voltage are examined.

전압 특성에 따른 LPLi 연료펌프 성능 연구

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 60nm at each experimental condition.

디젤엔진에서의 매연 입자 배출 특성

In this research, we have developed a system for ECU in the loop simulation to evaluate the performance of a vehicle dynamics controller which is a kind of active stability control units to control wheel slip and to improve steering stability of a vehicle on the road under rainy and snow conditions by controlling brake pressure and engine torque. To operate the VDC module, wheel speeds, a steering angle, master cylinder pressures, a yaw rate and a lateral acceleration of the vehicle and engine operation conditions are necessary as input information, then the brake pressures of each wheels could be calculated for keeping the vehicle stability in the module. The performance test of the developed system has been done according to JASO rules. We can get satisfied results of the developed ECU HILS through a series of experiments.

차량 자세제어 장치를 위한 ECU in the Loop System 개발

In order to investigate the effect of heated temperature on fuel injection rate for fuels such as light oil, blend of rice bran oil and light oil, and pure rice bran oil as a parameter of injection pump rack stroke, tests are performed by an injection pump tester at three kinds of cam shaft speed. In this study, also, the effects of rice bran oil properties on the fuel economy and exhaust emissions are experimentally examined by a single cylinder, four cycle, direct injection, water-cooled diesel engine operating at several engine loads and speeds. The fuel injection timing is fixed to 22° BTDC regardless of fuel types, engine loads and speeds. The kinematic viscosity of rice bran oil is very high compared with light oil. Also, the oxygen is not contained at all in light oil, while the oxygen contents of 10.7% are included in rice bran oil. In this study, results show that fuel injection rate increases as injection pump rack stroke and cam shaft speed are elevated at the same conditions, and as heated temperature is elevated with the exception of light oil. It is also found that brake specific fuel consumption rate and NO x emissions increase, while soot emissions decrease as the blending rate of rice bran oil is enriched. Thus we can conclude that the combustion process which affect the fuel economy and exhaust emissions of diesel engines using rice bran oil as a fuel is controlled by the differences of chemical and physical properties.

디젤기관 대체연료 미강유의 분사율 및 배기 배출물 특성

Minimizing the cylinder wear and the consumption rate of cylinder oil in a large two-stroke diesel engine is of great economic importance. A motor-driven cylinder lubricator for Sulzer RT-flex large two-stroke diesel engines developed by authors is in need of mounting a quill system to lubricate cylinder parts for smoother operation. In order to apply the common-rail lubricating system to the developed cylinder lubricator as the second research stage, the quill system with a progressively quantitative distributor is improved in the electronically controlled quill system with an accumulated distributor. In this study, the effects of lubricator motor speed, plunger stroke and cylinder back pressure on oil feed rate, maximum discharge and delivery pressures are experimentally investigated by using the electronically controlled quill system with an accumulated distributor in the developed cylinder lubricator. It is found that the oil feed rate of the electronically controlled quill system with an accumulated distributor is larger than that of the quill system with a progressively quantitative distributor because of the increase of delivery speed and volume by changing the location of accumulator in the same experimental condition.

한영욱

Papers

디젤기관 대체연료 미강유의 분사율 및 배기 배출물 특성

대형 2행정 디젤기관에 있어서 실린더 주유기용 전자제어 퀼 축압분배기 개발