In order to investigate the effectiveness of methanol, which has high latent heat of evaporation and oxygen contents, for DI diesel engine performance and exhaust emission, the methanol was injected at the suction port of DI diesel engine. The injector used for test was conventional gasoline engine injector and controlled the quantity of methanol per cycle by the power supply controller which designed specially for injector. The results shown that the maximum pressure point was delayed, the value of maximum pressure was decreased, and the concentrations of both NOx and Soot were decreased, as the methanol injection quantity increased, and also the thermal efficiency of engine injected methanol under the high load condition was similar to no methanol injection but under the medium load condition was decreased within the experimental conditions.

This study was conducted on the properties of exhaust emissions of diesel oil and fish oil blended with diesel oils using a direct injection diesel engine at different loads, and on the conditions of carbon deposits of diesel oil and 40% blend oil in the combustion chamber after 20 hours operation at 1]2 load. The properties of exhaust emissions by fish oil blended with diesel oils showed no significant difference with diesel oil. However, soot emissions decreased, increasing the ratio of fish oil. Carbon deposits by fish oil blended with diesel oils were high level compared with diesel oil, which might be overcome by preheating of fuel oil and operating conditions.

터보 노즐에 유동하는 가스 에너지의 변화와 그위상의 조정에 의하여 디젤엔진의 성능 개선 가능성을 검토 하였다. 그리고 디젤기관의 각실린더와 터빈 노즐 면적과 가스의 유동에 대한 동기화를 실시함으로써 엔진 성능 또한 개선할 수 있었다.

The energy saving is one of the most important factors for profit in marine transportation. In order to reduce the fuel oil consumtion the ship's propulsion efficiency must be increased as possible. The propulsion efficiency depends upon a combination of an engine and a propeller. The propeller has better efficiency as lower rotational speed. This situation led the engine manufacturers to design the engine that has low speed, long stroke and a small number of cylinders. Consequently, the variation of rotational torque became larger than before because of the longer delay-time in fuel oil injection process and an increased output per cylinder. As this new trends the conventional mechanical-hydrualic governors for engine speed control have been replaced by digital speed controllers which adopted the PID control or the optimal control algorithm. But these control algorithms have not enough robustness to suppress the variation of the delay-time and the parameter perturbation. In this paper we consider the delay-time and the perturbation of engine parameters as the modeling uncetainties. Next we design the robust servo controller which has zero offset in steady state engine speed, based on H sub(∞) control theory. The validity of the controller was investigated through the response simulation. We used a personal computer and an analog computer as the digital controller and the engine (plant) part respectively. And, we could certify that the designed controller maintains its robust servo performance even though the engine parameters may vary.

The combustion characteristics of diesel oil and fish oil blended with diesel oils were investigated at various blending rate of fish oil in diesel engine and constant volume combustion bomb. The evaporation and combustion duration of diesel oil and fish oil blended with diesel oils were respectively different high and low temperature. The dependence of ignition delay on the temperature was different in high and low temperature ranges which were divided at the 773K. The ignition delay become longer than that of diesel oil as the blending rate of fish oil increases, and its difference were larger at different loads. The densityof smoke was lower as the blending rate of fish oil increases, and the rate offuel consumption showed no significant difference between diesel oil and fish oil blended with diesel oils.

In 1980 s to 1990 s the marine propulsion diesel engines have been developed into lower speed and longer stroke for the enegy saving (small S.F.O.C). As these new trends the conventional mechanical-hydraulic governors were not adapted to the new requirements and the digital governors have been adopted in the marine use. The digital governors usually use the control algorithms such as the PID control, optimal control, adaptive control and etc. While the engine has delay time and parameter variations these control algorithms have difficulty in considering the stability and the robustness for the model uncertainty. In this study, the H∞ controller design method are applied in order to design the feedback controller K(s) to the speed control of the low speed marine diesel engine, and the two-degree-of-freedom control system is constituted with H∞controller. By comparison of responses of the two-degree-of-freedom control system under the delay time and parameter variations is confirmed.

예연소실식 디젤기관에 있어서 박용부하운전조건에 따른 연소특성을 규명하기 위해 예언소실의 압력데이터를 single-zone, single-chamber의 열역학적 해석에 적용하여 연소해석을 행한 결과 다음과 같은 결론을 얻었다. 1) 부하가 증가함에 따라 최고압력이 상승하고 그 위치가 크랭크각도상 후진되었다. 2) 착화 지연시간은 부하에 관계없이 거의 일정하고, 부하가 증가할수록 가연 혼합기 형성에 소요되는 흡열량은 겉보기로 감소하였다. 3) 예혼합 연소단계의 열발생 양상은 부하에 관계없이 거의 비슷하고, 예혼합 연소시간은 부하가 증가할수록 짧아졌다. 4) 부하가 증가함에 따라 예혼합 연소량은 다소 증가하나 일정 연공비 이상에서는 거의 일정했다. 5) 예혼합 연소분율은 부하가 증가함에 따라 감소했다.(이 논문의 결론부분임)

This paper is an experimental study to investigate utility of ultrasonic treatment of fuel oil in diesel engine. Experiment was carrid out to clarify the effect of ultrsonic vibration on the characteristics of maximum pressure, fuel consumption ratio, smoke, BMEP and torque. The result obtained are as follows: 1. In the case of given ultrsonic vibration, the maximum pressure is increased in all experimental conditions. 2. In the case of given ultrsonic vibration, the decrease effect of fuel consumption rate is increased at low rpm. 3. The generation quantity of soots is increased according to load. In the case of given ultrsonic vibration, the decreased quantity of soots does not very according to load. 4. In the case of given ultrsonic vibration, the BMEP and torque are increased at low load.

국산 소형어선용 예연소실식 디젤기관의 연료유를 가열할 경우, 연소특성 및 기관성능에 미치는 영향에 관하여 실험한 결과를 요약하면 다음과 같다. 1) 연료유 분사시작점은 연료유 가열온도의 증가에 따라 늦어지는 경향을 나타냈으며, 특히 저부하 운전시 늦어지는 경향이 현저했다. 2) 연소최고압력점은 연료유 가열온도의 증가에 따라 늦어졌으며, 연소최고압력은 연료유 가열온도 증가에 따라 감소하였으나 부하의 증가에 따라 증가하는 경향을 나타내었다. 3) 연료소비율은 부하의 증가에 따라 감소하였으며, 연료소비율이 가장 작은 연료유의 최적가열온도는 150℃부근임을 나타내고 있다. 4) 그을음농도는 부하와 연료유 가열온도의 증가에 따라 증가하는 경향을 나타냈다.