超稀薄燃烧对汽油发动机性能影响的试验研究

Experimental Research on the Effect of Ultra-lean Combustion on the Gasoline Engine Performance

均质超稀薄燃烧技术作为实现45%+热效率的关键技术之一,缸内最高燃烧温度较当量比燃烧低,可有效降低爆燃倾向,在超高压缩比下提高点火角,同时提高比热比,进而提高热效率,随着过量空气系数的提高,燃烧温度降低,从而获得较低的NO_(x)排放。在此背景下研究汽油机超稀薄燃烧性能。在一款热力学单缸机上应用电晕点火系统、快速燃烧系统和超高压缩比技术等,研究汽油机超稀薄燃烧(过量空气系数>1.8)的燃烧、油耗和排放情况。试验验证发现,采用电晕点火高电压及较长持续时间可以获得过量空气系数2.2以上稳定燃烧,在2000 r/min及IMEP 10 MPa,过量空气系数2.25时,发动机的指示燃油消耗率为170.5 g/(kW·h),并获得较低的NO_(x)原始排放。

Homogeneous lean combustion is a key technology to achieve more than 45%thermal efficiency of the gasoline engine and knocking suppression due to the lower maximum combustion temperature than the stoichiometric combustion.Advanced ignition timing in the case of ultra-high compression ratio and specific heat ratio can also improve thermal efficiency.With the increase of excess air coefficient,the engine obtains a lower NO_(x) due to lower combustion temperature.Under this background,this paper studies the ultra-lean combustion performance of the gasoline engine.In this paper,we study the combustion,fuel consumption and emission of ultra lean combustion(φa>1.8)at a thermodynamic single cylinder engine which applied corona ignition system,fast combustion system and ultra high CR technology.And we have achieved the best ISFC,170.5g/(kWh),the engine indicated thermal efficiency about 49.5%,with low NO_(x) emission at 2000 r/min,IMEP10 MPa and lambda 2.25.