The Study of Combustion Characteristics in the Diesel Engine by Utilizing Both Zero-Dimensional Simulation and Experimental Measurements

• Main Authors: Ming-Hung Wei, 魏銘宏
• Other Authors: Shih Kuo-Liang
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/65044199531094039823

碩士 === 國立雲林科技大學 === 機械工程技術研究所 === 83 === The goal of this study is to investigate combustion characte- ristics of fuel-air mixture in diesel engine cylinder. Actual analyses of these simulation results,i.e.,the cylinder pressure ,average gas temperature,and fuel heat release rate, etc.,are essential fundamental information toward fully understanding and good prediction of engine performance in advance. Also experimental measurements of engine pressure,torque,and power output, etc., are another extremely useful knowledge in engine analysis. Both simulation and experimental results have been compared in this research to study combustion characteristics in dieselengine which can be used for improving engine efficiency in the engine design company. The YAMAHA ME200F (three cylinders, 1973 CC, direct-injection) diesel engine in the laboratory and a zero-dimensional diesel engine simulation program (DESP) are selected to perform this research. The engine speed, load (equivalence ratio), and fuel injection timing are varied to study their effects on air-fuel mixing and combustion processes in the diesel engine. The experiments are also conducted simultaneously to measure the engine torques in various operating conditions through cautions appropriate experimental procedures. The results show that the ignition delay increases almost linearly with engine speed increasing at constant load. The most efficient engine operating speed for ME200F diesel engine is found to be near 2000 rpm due to the corresponding maximum brake mean effective pressure (BMEP) and the minimum specific fuel consumption (SFC) occurrence at this speed. As the engine load is increased, the ignition delay is shortened slightly due to increaseed cylinder charge temperature and pressure at time of injection. Increasing of engine load results in a reduction of brake spefic fuel consumption(BSFC)but a increment in bmep. The results also show that the engine brake power increases slowly with engine speed at high engine speed condition, especially at low engine load cases, this is primarily due to the quick non-proportional increment of friction force between engine moving parts at high speed. Another parametric study shows that if fuel injection timing is advanced, the ignition delay will be increased because the initial air temperature and pressure are relatively low in cylinder. According to DESP simulation results, the engine will operate with higher brake power output and better BMEP and SFC values at injection timing of 29 degree BTDC than the default value of 24 degree BTDC used in the actual engine. Thus, it is suggested that the optimum fuel injection timing for YAMAHA ME200F diesel engine should be at 29 degree BTDC. The experimental results show that the engine's maximum load φ=0.3 and φ=0.5 occurs at 500 rpm and 1000 rpm, respectively. On the opposite, its minimum load φ=0.3 occurs at high speed 3000 rpm. The comparison of engine's torque, power output, and BSFC between DESP program simulation results and experimental results is found very consistent in this study.