摘要
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。
For the cold start problem of methanol engine,one 1130 single-cylinder diesel engine was retrofitted to direct injection spark ignition methanol engine and the influences of ignition timing on methanol combustion and non-compulsory emission during cold start at 266 Kwere researched by simulating the oxidation reaction mechanism of methanol with AVL-Fire software and preheating the intake to 283 Kwith 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 emission decreases obviously when the ignition timing is 17°CA BTDC and the in-cylinder peak temperature is beyond 1 300 K.
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