气相射流点火天然气发动机的燃烧及排放特性

射流点火是实现稳定的稀薄燃烧,大幅度提升发动机热效率的有效技术途径。该文利用设计的一种射流点火器,对气相射流点火(GJI)的燃烧开展研究,揭示了主动式射流点火(射流室内有补充燃料)和被动式射流点火(射流室内无补充燃料)的燃烧和排放特性。结果表明:相比于被动式射流点火,主动式射流点火将过量空气系数拓展至2.0,热效率提升1.5%;进一步引入废气再循环(EGR)后,热效率提升至44.5%。主动式射流点火时,最高热效率点NOx排放较被动式射流点火下降低66%,THC及CO排放的增加使燃烧效率降低3%;引入EGR后,NOx进一步降低79%,燃烧效率保持稳定在96%。

Characteristics of combustion and emission of natural gas engine using gas-jet ignition

Jet ignition is an efficient way to achieve lean burn and improve thermal efficiency of the engine.Gas-jet ignition(GJI)combustion was studied with the designed jet igniter,and the characteristics of combustion and emission under passive jet ignition and active jet ignition strategies were investigated.The results show that active ignition extends the excess air ratio to 2 and thermal efficiency is improved 1.5%compared with passive ignition,and based on the active jet ignition,thermal efficiency is further improved to 44.5%when exhaust gas recirculation(EGR)is introduced.The NOx emission at the most efficient point decreases 66%with active jet ignition,whereas the combustion efficiency decreases 3%due to the increase of THC and CO emission.NOx emission further decreases 79%and combustion efficiency keeps stable at 96%with the introduction of EGR.