摘要
均质稀薄燃烧技术由于可大幅提高汽油机效率而成为发动机主要的发展方向之一,稀薄燃烧能够有效降低缸内燃烧温度,抑制爆震,从而允许点火角提前和增大压缩比。同时,减小发动机喷油加浓区域和降低冷却热损失,此外,还可在一定程度上降低发动机部分负荷的泵气损失功,以及有效降低NOx排放,但是随着过量空气系数的升高,缸内混合气体的燃烧变得更加困难,循环波动率增大,甚至会出现失火等现象,以及燃烧持续期加长,缸内温度下降,工质做功能力会下降。故需要匹配高效的点火系统,以获得稳定的燃烧,探索合适的过量空气系数范围是稀薄燃烧技术应用的关键。在此背景下,探索研究稀薄燃烧对于发动机油耗和NO_x排放的影响。应用高效点火系统,研究高效点火稀薄燃烧特性,以及稀燃情况下的燃烧、油耗和排放情况。试验验证发现,应用高效点火和稀薄燃烧技术之后,在2 416 r/min,BMEP 0.86 MPa,过量空气系数1.51时,获得最低有效燃油消耗率BSFC为203.85 g/(kW·h),发动机热效率约为41%,指示燃油消耗率193.41 g/(kW·h),指示热效率为43.3%。
Homogeneous lean combustion technology can significantly improve the thermal efficiency of gasoline engine and has become one of the main development directions of internal combustion engine.Temperature in cylinder during lean combustion can be greatly reduced, thus suppress knocking, allow the ignition angle advanced and the compression ratio increased, at the same time, can reduce the engine fuel enrichment area and the cooling heat loss. In addition, it can reduce the engine pumping losses in some extent, and effectively reduce NO_x emissions. But with the increase of Lambda, combustion of mixed gas in cylinder become difficult, and the COV increased, even the misfire appears, and combustion duration extends, and the temperature decreases in cylinder, working medium power capability decreases. It is the key to find the suitable Lambda range for the lean burn. In this context, the effects of lean combustion on engine fuel consumption and NO_x emission are investigated.In this paper, the high efficiency ignition system is used to study the combustion, fuel consumption and emission of lean combustion. The experimental results showed that, due to application of high-efficiency ignition and lean combustion technology, the BSFC was 203.85 g/kWh, the brake engine thermal efficiency achived 41% and the ISFC was 193.41, which meant the indicated thermal efficiency was 43.3%,at 2416 rpm, BMEP8.6 bar and lambda 1.51.
引文
1节能与新能源汽车技术路线图战略咨询委员会,中国汽车工程学会.节能与新能源汽车技术路线图[M].北京:机械工业出版社,2016
2 Li Shuangqing, Yu Jingzhou, Wang Zhiwang, et al. Development of GEELY low pressure EGR technology[R]. SAE EVENT/PFL180. Detroit:SAE WCX, 2018
3 周少任,张煜盛.内燃机脉冲电晕放电点火研究现状与发展方向[J].车用发动机,2006(5):7-11
4 Williams J, Yokoo N, Nakata K, et al. The impact of fuel composition on the combustion and emissions of a prototype leanboosted PFI engine[R]. SAE Technical Paper 2010-01-2094
5 Rixecker G, Brichzin V, Becker M, et al. Corona ignition as an enabler for lean combustion concepts leading to significantly reduced fuel consumption of turbocharged gasoline engines[C]. Proceedings of the 22nd Aachen Colloquium Automobile and Engine Technology, 2013
6 Marko F, K?nig G, Sch?ffler T, et al. Comparative optical and thermodynamic investigations of high frequency Corona-and spark-ignition on a CV natural gas research engine operated with charge dilution by exhaust gas recirculation[C]. International Conference on Ignition Systems for Gasoline Engines.Springer, Cham, 2016:293-314
