摘要
针对某国Ⅵ天然气发动机开展了提升进气混合均匀性和发动机经济性的试验,分析了进气系统结构优化(包含加装扰流器)对进气混合均匀性的影响;同时研究了高低压废气再循环(EGR)技术(即EGR从涡轮机前取气而从压气机前引入)对发动机燃烧和性能的影响规律以及探索了其实现高效燃烧的潜力.结果表明:对进气系统结构的优化能显著改善混合气的混合均匀性,减少各缸燃烧差异从而改善发动机经济性.高低压EGR技术的应用能显著减小EGR引入对高涡前压力依赖的需求,相比高压EGR方案可匹配更大涡端增压器同时满足对大比例EGR率的需求,从而显著降低泵气损失;并且高低压EGR技术降低了进气歧管温度来提高充量系数;此外,采用高低压EGR技术延长了混合气的混合时间尺度,进一步提高混合均匀性.最终,更加高效的燃烧和较低的泵气损失使发动机有效热效率(BTE)从原机水平39.12%提升至40.63%,改善幅度达3.9%.
An experimental study on increasing the mixing uniformity in the intake manifold and improving the fuel economy was carried out on a China Ⅵ natural gas(NG) engine. Firstly,a structure optimization of the intake system,including the installation of a spoiler,on the mixing uniformity was analyzed. Then,an influence of the high and low pressure exhaust gas recirculation(EGR) system on engine combustion and performance was studied. Finally,the potential of achieving high efficient combustion was explored. The results show that the structure optimization of the intake system can significantly improve the uniformity of the mixture,leading to a reduction of the cylinder-to-cylinder combustion variation and an improvement of the engine fuel economy. The application of high and low pressure EGR system can easily introduce a desired EGR amount by not relying heavily on a high preturbine exhaust pressure,which allows to use a larger turbocharger. As a result,the pumping loss is significantly reduced. Meanwhile,the high and low pressure EGR system decreases the intake manifold temperature and extends the mixing time for a better mixing uniformity. Experiment results show that more efficient combustion and lower pumping losses make the brake thermal efficiency(BTE)of the engine to increase from 39.12% in baseline to 40.63%,an improvement of 3.9%.
作者
官维
盛利
王辉
林铁坚
Guan Wei;Sheng Li;Wang Hui;Lin Tiejian(Guangxi Yuchai Machinery Company Limited,Yulin 537000,China)
出处
《内燃机学报》
EI
CAS
CSCD
北大核心
2023年第1期25-32,共8页
Transactions of Csice
基金
广西重点研发计划资助项目(桂科AB21220055)。
关键词
天然气发动机
高低压废气再循环
混合均匀性
燃烧特征
natural gas engine
high and low pressure exhaust gas recirculation
mixing uniformity
combustion characteristics
