喷射时刻对甲醇热氛围燃烧影响的试验  

Experimental Study on Effect of Injection Timing on Thermo-Atmosphere Combustion of Methanol

作　　者：陈征[1] 尧命发[1] 郑尊清[1] 张全长[2] 

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 [2]广西大学机械工程学院,南宁530004

出　　处：《天津大学学报》2007年第10期1159-1164,共6页Journal of Tianjin University(Science and Technology)

基　　金：国家自然科学基金资助项目(50376046);国家自然科学重点基金资助项目(50636040)

摘　　要：利用进气预混合二甲醚(DME)在缸内早燃形成的热氛围,研究了不同甲醇浓度下喷射时刻对缸内直喷甲醇热氛围燃烧的影响.结果表明:醇燃料在上止点附近喷射,燃烧过程表现为DME低温放热、高温放热和甲醇扩散燃烧放热3个阶段的分布式放热规律;随甲醇喷射时刻的提前,燃烧变为双峰放热,且第2放热峰值增大.较早的喷射时刻易导致爆震或者失火,燃烧过程较难控制.不同甲醇浓度下喷射时刻对发动机性能和排放特性的影响有所不同.值得注意的是,随甲醇浓度的增大,DME热值比例减小.综合比较,甲醇在上止点前22°CA附近喷射,能获得较好的发动机综合性能.The effect of injection timing at various methanol concentrations on thermo-atmosphere combustion of methanol was investigated experimentally. The results show that, when injection occurred near top dead center （ TDC ）, the combustion process comprises three stages： low temperature reaction of dimethyl ether （ DME ）, high temperature reaction of DME, and diffusion combustion of methanol. With injection occurred earlier, the combustion process transforms into two-stage heat release, and the second stage peak of heat release increases. Earlier injection easily causing knocking or misfire, thus makes the combustion process difficult to control. The effects of injection timing at various methanol concentrations on performance and emissions of the engine are different. It is noted that DME ratio decreases with increasing methanol concentration. In conclusion, better integrated performance can be achieved when methanol is injected near 22° CA before TDC.

关 键 词：喷射时刻 甲醇 二甲醚 热氛围 

分 类 号：TK407.9[动力工程及工程热物理—动力机械及工程] TQ923[轻工技术与工程—发酵工程]