进气组分对低速船机NO_x排放的影响  

Impact of Air Intake Components on NO_x Emissions in Low-Speed Marine Diesel Engine

作　　者：刘海峰[1] 张慧祥 王浒[1] 邹宪[1] Liu Haifeng;Zhang Huixiang;Wang Hu;Zou Xian(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China)

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》2017年第4期313-319,共7页Journal of Combustion Science and Technology

基　　金：国家科技支撑计划资助项目(2015BAG16B00)

摘　　要：使用多维数值模拟方法,研究了采用废气再循环、进气加湿耦合喷油策略改善低速二冲程船机NO_x-ISFC(指示燃油消耗率)折衷关系的潜力.研究表明,EGR的稀释效应和热效应是降低缸内燃烧温度的主要原因,但稀释效应使得氧浓度降低,从而使得燃烧速率降低,燃烧持续期加长,导致油耗恶化;进气加湿引入量小,因而稀释效应的作用较小,大比例加湿的热效应作用较强是降低缸内燃烧温度的主要原因,而且少量的进气加湿对缸内燃烧过程和油耗影响较小.结果表明,EGR率为30%,,进气加湿量与喷油量的比值为1.5,喷油时刻为上止点后1°,CA,可在略微牺牲经济性的前提下,将NO_x降低90.5%,,满足TierⅢ排放法规的要求.In the current study,multi-dimensional numerical simulations are conducted to explore the potential ofEGR and intake humidifying coupling with injection strategy optimization to improve the trade-off relationship ofNOx-ISFC(indicated specific fuel consumption)in a low-speed two-stroke marine engine.The results show that thedilution and thermal effects of EGR are the main reasons for the lower combustion temperature.However,theoxygen concentration is also reduced as EGR increases,thus reduced combustion reaction rate,prolonged combustionduration and retarded combustion phasing are observed,resulting in deteriorated fuel economy.The dilutioneffect is weak for intake humidifying due to the relatively small water quantity;however,the high heat capacityof water vapor results in much stronger thermal effect,which is the main reason for the much lower combustiontemperature.In addition,a small amount of air intake humidifying has a insignificant influence on combustionand fuel economy.NOx can be reduced by90.5%,with a minor penalty on fuel economy by using30%,EGRcombined with1.5,(water to fuel ratio)and slightly retarded SOI timing(1°,CA after the top dead center),whichcan meet the TierⅢemission regulations.

关 键 词：二冲程船用柴油机 NOX排放 废气再循环 进气加湿 喷油时刻 

分 类 号：TK448.21[动力工程及工程热物理—动力机械及工程]