摘要
为探究稀释燃烧改善发动机性能的潜力,通过一台1.5 L高压缩比增压直喷汽油机开展台架试验,对比研究了空气稀释、废气再循环(EGR)稀释及复合稀释燃烧在不同稀释程度下对中速、中负荷工况下发动机性能的影响规律.结果表明:稀释燃烧延长了燃烧持续期,降低了有效燃油消耗率(BSFC),减少了发动机传热损失,并降低了CO排放,稀释方式不同会导致HC和NO_(x)排放随稀释率的变化规律不同,但在高稀释率下,相比无稀释燃烧,HC排放升高,NO_(x)排放降低;相较于EGR,空气稀释对燃烧的抑制更弱,稀释边界更宽,BSFC降低效果更好,CO与HC排放显著更低,未燃损失更低,NO_(x)排放更高,且这些规律在相同稀释率、不同EGR占比的复合稀释燃烧的性能参数变化中同样存在,但有效热效率在过量空气系数φa=1.34、EGR率约为5%(稀释率为1.4)时达到最高,这与排气损失更低有关,此时相较原机,BSFC降低了5.7%,NO_(x)降低了33%,均比φ_(a)为1.40时的降幅更大,证明了复合稀释燃烧具备更强的节能减排潜力.
In order to investigate the potential of dilution combustion on engine performance improvement,a 1.5 L turbocharged direct injection gasoline engine with high compression ratio was used to conduct a bench test to compare the effect of lean burn,exhaust gas recirculation(EGR)and lean dilution combustion on engine performance at medium speed and load conditions under different degree of dilution defined as dilution rate.The results show that dilution combustion extends the combustion duration,reduces heat transfer losses,lowers the brake specific fuel consumption(BSFC),and reduces CO emissions.However,different dilution methods(lean burn and EGR)lead to different variation of HC and NO_(x)emissions with the increase of dilution rate.At high dilution rates,there are more HC emissions and lower NO_(x)emissions than undiluted combustion.Compared with EGR,lean burn has a weaker combustion inhibition,a wider dilution boundary for stable combustion,a lower fuel consumption,higher NO_(x)emissions,lower CO and HC emissions and unburned losses.The above laws also exist in the performance variation of lean dilution combustion at the same dilution rate with different percentage of EGR.In particular,the effective thermal efficiency reaches highest at a dilution rate of 1.4 with an EGR rate of 5%andφ_(a) of 1.34,which,according to the energy balance analysis,is related to lower exhaust losses.Under this condition,fuel consumption is reduced by 5.7%and NO_(x)is reduced by 33%compared with the equivalent ratio combustion,both of which are greater than the reduction whenφa is 1.40,which proves that the lean dilution combustion has a stronger potential to save energy and reduce emissions.
作者
楼狄明
赵彬皓
范本正
房亮
张允华
Lou Diming;Zhao Binhao;Fan Benzheng;Fang Liang;Zhang Yunhua(College of Automotive Studies,Tongji University,Shanghai 201804,China;SAIC Motor Corporation Limited,Shanghai 201804,China)
出处
《内燃机学报》
EI
CAS
CSCD
北大核心
2023年第5期427-434,共8页
Transactions of Csice
基金
国家重点研发计划资助项目(2021YFB2500801).
关键词
增压直喷汽油机
稀释燃烧
有效燃油消耗率
turbocharged direct injection gasoline engine
dilution combustion
brake specific fuel consumption
