柴油微引燃天然气发动机中高负荷QHCCI燃烧试验  

Experiment of Mid-Load and High-Load QHCCI Combustion on a Natural Gas Engine with Diesel Micro-Ignition

作　　者：刘亚龙[1] 毋波 邬斌扬[1] 苏万华[1] Liu Yalong;Wu Bo;Wu Binyang;Su Wanhua(State Key Laboratory of Engines,Tianjin University,Tianjin 300350,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300350

出　　处：《内燃机学报》2022年第6期481-488,共8页Transactions of Csice

基　　金：国家重点研发计划资助项目(2017YFB0103501);天津市自然科学基金资助项目(19JCYBC21200)。

摘　　要：柴油微引燃天然气发动机准均质充量压燃着火(QHCCI)燃烧具有低碳、高效、清洁运行的潜力.通过一台潍柴WP12改造的柴油微引燃天然气发动机,探究了废气再循环(EGR)、进气门晚关(LIVC)、引燃柴油喷射定时和燃氧当量比φ_(o)在大、中负荷工况下对天然气QHCCI的影响.结果表明:大负荷下提高EGR率,有利于QHCCI向更高负荷拓展,但会降低缸内工质比热比,不利于总指示热效率(ITE_(g))提高;通过LIVC技术,降低有效压缩比,避免粗爆燃烧,也有利于QHCCI向大负荷拓展.通过采用LIVC技术结合低EGR率的技术可使QHCCI在大负荷下高效燃烧,经优化后,在低转速、大负荷工况、p_(in)=0.30 MPa、φ_(o)=0.79、EGR率为15%、引燃柴油喷射能量为3%和引燃柴油喷射定时为-3°CA ATDC的条件下,ITE_(g)达到47.50%.中等负荷下,通过引燃柴油喷射定时与φ_(o)的协同控制可对燃烧相位和燃烧速率进行优化,最后在p_(in)=0.18 MPa、φ_(o)=0.50、EGR率为0%、引燃柴油喷射能量为5%且引燃柴油喷射定时为-10°CA ATDC的条件下,ITE_(g)达到49.79%.Quasi homogeneous charge compression ignition(QHCCI)combustion of natural gas engine with the diesel micro-ignition has the potential for low-carbon,efficient and clean operation.The influence of exhaust gas recirculation(EGR),late intake valve closure(LIVC),pilot diesel injection timing and fuel oxygen equivalent ratioφ_(o) on the QHCCI combustion process was experimentally explored on a diesel micro-ignition natural gas engine modified by a Weichai WP12 diesel engine under heavy and medium load conditions.The results show that increasing the EGR rate under high-load is beneficial to realize an extension of QHCCI combustion to higher load,but it will reduce the specific heat ratio of the working fluid,which is not conducive to the improvement of the gross indicated thermal efficiency(ITE_(g)).Reducing the effective compression ratio through LIVC technique can avoid knocking combustion and also conducive to the extension of QHCCI combustion to high-loads.Using LIVC combined with low EGR rate,the QHCCI combustion can be efficiently achieved under high-load.After optimization,the ITE_(g) reaches 47.50%at a low speed and high-load operation point,p_(in)=0.30 MPa,φ_(o)=0.79,the EGR rate of 15%,the pilot diesel injection energy of 3%and pilot diesel injection timing of-3°CA ATDC.For mid-load opera-tion,the combustion phase and combustion rate can be optimized through coordinated control of pilot diesel injection timing andφ_(o).As a result,the ITE_(g) reaches 49.79%at p_(in)=0.18 MPa,φ_(o)=0.50,the EGR rate of 0%,the pilot diesel injection energy of 5%and the pilot diesel injection timing of-10°CA ATDC.

关 键 词：天然气发动机 柴油微引燃 准均质充量压燃着火 燃烧相位 燃烧速率 

分 类 号：TK423.2[动力工程及工程热物理—动力机械及工程]