Sources of Hydrocarbon Emissions from Low-Temperature Premixed Compression Ignition Combustion from a Common Rail Direct Injection Diesel Engine
Sources of Hydrocarbon Emissions from Low-Temperature Premixed Compression Ignition Combustion from a Common Rail Direct Injection Diesel Engine
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DOI：
10.1080/00102200802530066
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发表时间：
2009-02
影响因子：
1.9
通讯作者：
Manbae Han;D. Assanis;S. Bohac
中科院分区：
文献类型：
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作者：
Manbae Han;D. Assanis;S. Bohac
低温预混压缩点火燃烧（PCI）在这项研究中讨论的是实现通过晚喷射定时（接近上止点）和重型废气再循环（EGR）使用超低硫瑞典柴油（硫含量小于15 ppm）。与观察到PM-NOx折衷的常规燃烧相反，在喷射正时延迟的情况下，PCI获得颗粒物（PM）和氮氧化物（NOx）的同时减少。在PCI中，碳氢化合物（HC）和一氧化碳（CO）增加，并且必须使用后处理去除。为了了解来自PCI制度的HC的来源，采用具有火焰离子化检测器的气相色谱法在三个EGR率和三个喷射正时下进行排气HC形态分析。挥发性HC、半挥发性HC和CO随着喷射正时延迟或EGR增加而增加。延迟的喷射正时或增加的EGR降低了峰值气缸本体温度，从而增加了CO和挥发性HC（主要是C1-C3）的产率。延迟的喷射正时或增加的EGR也增加了点火延迟，这增加了过度混合，并导致更多的混合物变得如此稀薄，以致于燃烧停止，并且半挥发性HC物质（主要是未燃烧的C10-C12燃料）的输出增加。挥发性HC物质比半挥发性HC物质增加更多，这导致随着喷射正时延迟或EGR增加而转变为较轻的排气HC混合物。
Low-temperature premixed compression ignition combustion (PCI) discussed in this study is achieved via late injection timing (close to top dead center) and heavy exhaust gas recirculation (EGR) using ultra low sulfur Swedish diesel fuel (sulfur content less than 15 ppm). PCI obtains a simultaneous decrease in particulate matter (PM) and oxides of nitrogen (NOx), as where injection timing is retarded, as opposed to conventional combustion, where a PM-NOx trade-off is observed. In PCI, hydrocarbon (HC) and carbon monoxide (CO) are increased, and must be removed using aftertreatment. In order to understand the sources of HC from the PCI regime, gas chromatography with a flame ionization detector is employed to perform exhaust HC speciation at three EGR rates and three injection timings. Volatile HC, semi-volatile HC, and CO increase as the injection timing is retarded or EGR is increased. Retarded injection timing or increased EGR reduces peak cylinder bulk temperature and thereby increases the yield of CO and volatile HC (mostly C1–C3). Retarded injection timing or increased EGR also increases ignition delay, which increases over-mixing and causes more mixture to become so lean that combustion ceases and the output of semi-volatile HC species (mostly unburned C10–C12 fuel) is increased. Volatile HC species are increased more than semi-volatile HC species, which results in a shift to a lighter exhaust HC mixture as injection timing is retarded or EGR is increased.