废气再循环对二甲醚/天然气双燃料均质压燃燃烧过程和排放特性的影响  

Experimental Study on the Effects of EGR on HCCI Combustion Process and Emissions of DME/CNG Dual Fuel

作　　者：郑尊清[1] 尧命发[1] 

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072

出　　处：《燃烧科学与技术》2004年第3期260-264,共5页Journal of Combustion Science and Technology

基　　金：国家重点基础研究发展规划资助项目(2001CB209201);国家自然科学基金资助项目(50106007).

摘　　要：在一台单缸直喷式柴油机上研究了冷却废气再循环(EGR)对二甲醚(DME)/天然气(CNG)双燃料均质压燃(HCCI)燃烧过程和排放的影响.结果表明,EGR率加大,着火时刻滞后,放热速率降低,燃烧持续期延长.DME比例加大,着火始点提前,放热率峰值上升,燃烧持续期缩短.EGR率增大,发动机"失火"和爆震燃烧的DME比例增大,但"失火"和爆震燃烧之间的DME比例区间变宽,EGR可以拓宽HCCI发动机的工况范围.对应不同比例的EGR,有一个热效率最佳的DME比例区域.HC排放和CO排放随EGR率的增高而增加,随DME比例的增大而降低.NOx排放在不发生爆震的情况下保持在极低的水平.因此,控制DME比例和EGR率是控制DME/CNG双燃料HCCI发动机燃烧过程、性能和排放的关键.Experimental study of effects of cooled exhaust gas recirculation (EGR) on homogenous charge compression ignition (HCCI) combustion process and emission characteristics was carried out on a single-cylinder direct injection diesel engine fueled with dimethyl ether (DME)/compressed natural gas (CNG) dual fuel. The results indicate that with the increase of EGR rate, the ignition time delayed, the heat release rate decreased, and the combustion duration extends. While the proportion of DME increases, the ignition time advances, the peak heat release rate increases, and the combustion duration decreases. Although the proportions of DME of misfire and knock both increases with the increase of EGR rate, the proportion range of DME between misfire and knocking is enlarged. So EGR can extend the operating range of HCCI engine. For each EGR rate, there is a proportion range of DME in which higher thermal efficiency can be obtained. HC and CO emissions both ascend with the increase of EGR rate, and decreased with the increase of the proportion of DME. NOx emission remains at a very low level except that knocking occurs. The control of the proportion of DME and EGR rate is the key technique to control the combustion process, performance and emissions of HCCI engine fueled with DME/CNG dual fuel.

关 键 词：二甲醚 天然气 均质压燃 废气再循环 燃烧 排放 

分 类 号：TK464[动力工程及工程热物理—动力机械及工程]