点火时刻对甲醇发动机燃烧及非法规排放的影响

针对甲醇发动机低温冷起动困难,在1台由1130单缸柴油机改造而成的直喷火花点火甲醇发动机上,利用CFD模拟软件AVL-Fire耦合甲醇氧化反应机理,通过电热塞将进气温度加热到283K,研究了点火时刻对甲醇发动机低温(266K)冷起动燃烧及非法规排放的影响。结果表明:提前点火时刻能够使缸内混合气得到较充分燃烧,减少未燃甲醇排放,当点火时刻由8°BTDC提前到11°BTDC时未燃甲醇排放显著减少;提前点火时刻能够降低甲醛排放,当点火时刻提前到17°BTDC、缸内最高燃烧温度超过1 300K时,甲醛快速氧化,甲醛排放显著减少。

Effects of Ignition Timing on Combustion and Non-compulsory Emission of Methanol Engine

For the cold start problem of methanol engine ,one 1130 single-cylinder diesel engine was retrofitted to direct injec-tion spark ignition methanol engine and the influences of ignition timing on methanol combustion and non-compulsory emission during cold start at 266 K were researched by simulating the oxidation reaction mechanism of methanol with AVL-Fire software and preheating the intake to 283 K with the electric heater plug .The simulation results show that advancing the ignition timing can improve the combustion and reduce the unburned methanol emission .When the ignition timing advances from 8°CA BTDC to 11°CA BTDC ,the unburned methanol emission decreases remarkably .Moreover ,formaldehyde oxidizes rapidly and its e-mission decreases obviously when the ignition timing is 17°CA BTDC and the in-cylinder peak temperature is beyond 1300 K .