柴油/汽油反应活性控制压燃发动机喷油协调控制与排放特性研究

对某4缸高压共轨柴油机进气道进行改造,搭建了柴油/汽油双燃料反应活性控制压燃(reactivity controlled compression ignition,RCCI)发动机专用试验台架,设计了柴油/汽油双燃料RCCI燃烧汽油喷射控制策略,实现了全工况下汽油与柴油的协调喷射控制,系统地研究了不同运行工况下,不同汽油替代率对柴油机燃烧与排放性能的影响规律。结果表明:采用柴油/汽油双燃料RCCI燃烧控制策略,发动机可在其运行工况范围内实现高效清洁燃烧,随着汽油替代率的增加,发动机缸内最高压力逐渐增大,缸压峰值出现时刻推迟,放热率峰值降低,燃烧持续期延长,燃油消耗率降低,有效热效率升高,全碳氢、CO排放增加,NOx和碳烟排放降低。

Study on Dual-Fuel Injection Coordination Control and Emission Performance of Diesel-Gasoline Reactivity Controlled Compression Ignition Engines

A 4-cylinder high pressure common rail diesel engine test bench was modified to work under Reactivity Controlled Compression Ignition (RCCI) combustion. The coordination control strategy model of gasoline injection was developed to adjust the combustion process and emissions, including the injection coordinator, the value of start of energizing time and gasoline quantity. The effects of different gasoline fraction on combustion and emission of diesel engine operated in RCCI mode under different operating conditions were studied. The results show that the diesel/gasoline RCCI combustion control strategy can achieve high efficiency and clean combustion. With the increase of gasoline fraction, the peak in-cylinder pressure increases gradually, the crank angle position at which peak pressure occurs in the cylinder delays slightly, the ignition timing is retarded and peak heat release rate decreases, and the brake specific fuel consumption (BSFC) decreases. When the engine operating under RCCI mode, the higher volatility and better overall fuel-air mixing improved the combustion and reduced the nitrogen oxide (NOx) and soot emission. And the emission of hydrocarbon (THC) and carbon monoxide (CO) increase due to the unburned fuel at low load operating conditions. The trade-off relationship between NOx and soot emission was solved perfectly. The results can provide a theoretical basis for RCCI combustion coordination control of diesel/gasoline.