Combustion visualization and experimental study on spark induced compression ignition (SICI) in gasoline HCCI engines
Combustion visualization and experimental study on spark induced compression ignition (SICI) in gasoline HCCI engines
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DOI：
10.1016/j.enconman.2009.11.029
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发表时间：
2010-05
影响因子：
10.4
通讯作者：
Zhi Wang;Xu He;Jian-xin Wang;S. Shuai;Fan Xu;Dongbo Yang
中科院分区：
文献类型：
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作者：
Zhi Wang;Xu He;Jian-xin Wang;S. Shuai;Fan Xu;Dongbo Yang
火花压燃(SICI)是一种较新的燃烧控制技术，是汽油机一种很有前途的高效燃烧方式。SICI可以分为两类，SACI和SI-CI。本文分别用燃烧可视化和发动机试验研究了SICI的燃烧过程。采用高速摄影技术，在不同压缩比的光学发动机上拍摄了SICI的着火过程。结果表明，SICI是一种部分火焰传播和主要自燃相结合的燃烧模式。火花点燃了火花电极附近的局部混合物，火焰传播发生在均匀混合物自动点燃之前。火焰传播引起的中心燃烧区放热增加了缸内压力和温度，导致未燃烧混合气自燃。SICI燃烧过程可分为火花诱导阶段、火焰传播阶段和压缩着火阶段。在燃烧和排放特性方面，SICI燃烧模式与火花点火(SI)敲击模式不同。在一台高压缩比、可切换凸轮型线的汽油直喷式发动机上，对HCCI、SICI、SI三种典型燃烧模式进行了对比分析。结果表明，SICI具有明显的燃烧特性，具有两级放热和较低的压力升高率。SICI燃烧模式可以通过点火定时和EGR率来控制，是提高汽油均质压燃发动机高负荷性能的一种有效方法。在较低的NOx排放和较高的热效率下，最大内燃机能达到0.82 Mpa。SICI燃烧模式适用于高效率汽油机的中高负荷区域。
Spark induced compression ignition (SICI) is a relatively new combustion control technology and a promising combustion mode in gasoline engines with high efficiency. SICI can be divided into two categories, SACI and SI–CI. This paper investigated the SICI combustion process using combustion visualization and engine experiment respectively. Ignition process of SICI was captured by high speed photography in an optical engine with different compression ratios. The results show that SICI is a combustion mode combined with partly flame propagation and main auto-ignition. The spark ignites the local mixture near spark electrodes and the flame propagation occurs before the homogeneous mixture is auto-ignited. The heat release from central burned zone due to the flame propagation increases the in-cylinder pressure and temperature, resulting in the unburned mixture auto-ignition. The SICI combustion process can be divided into three stages of the spark induced stage, the flame propagation stage and the compression ignition stage. The SICI combustion mode is different from the spark ignition (SI) knocking in terms of the combustion and emission characteristics. Furthermore, three typical combustion modes including HCCI, SICI, SI, were compared on a gasoline direct injection engine with higher compression ratio and switchable cam-profiles. The results show that SICI has an obvious combustion characteristic with two-stage heat release and lower pressure rise rate. The SICI combustion mode can be controlled by spark timings and EGR rates and utilized as an effective method for high load extension on the gasoline HCCI engine. The maximum IMEP of 0.82MPa can be achieved with relatively low NOxemission and high thermal efficiency. The SICI combustion mode can be applied in medium–high load region for high efficiency gasoline engines.