Effects of engine operating parameters on diesel low-temperature combustion with split fuel injection
Effects of engine operating parameters on diesel low-temperature combustion with split fuel injection
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DOI：
10.1177/0954407012440937
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发表时间：
2012-04
期刊：
影响因子：
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通讯作者：
A. Sarangi;C. P. Garner;G. McTaggart-Cowan;M. Davy;E. Wahab;M. Peckham
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文献类型：
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作者：
A. Sarangi;C. P. Garner;G. McTaggart-Cowan;M. Davy;E. Wahab;M. Peckham
本文表明，一个分裂的燃料喷射策略可以实现强大的，接近零的烟雾和氮氧化物的排放量在低温燃烧条件下减少废气再循环水平。这项工作的总体目标是研究50：50（按质量）分段喷射策略对关键发动机运行参数变化的敏感性（就发动机排放和燃油经济性而言）。在0.51升单缸高速直喷式柴油机上进行了总指示平均有效压力为500 kPa、转速为1500 r/min的工况试验。本文研究了在进气压力（120 kPa，绝对压力）不变的情况下，采用分段主喷射策略，在不同的进气氧质量分数（10.5%和12%）下，不同的相对喷油正时对烟度、总烃和一氧化碳排放的影响。还报道了可变燃料喷射压力（90 MPa和110 MPa）对柴油机低温燃烧与分流喷射的影响，以及增加的进气压力（150 kPa，绝对）的影响。描述了运行参数和喷油正时对烟度、氮氧化物、总烃和一氧化碳排放以及总指示油耗率的综合影响。对于选定的操作条件下，周期分辨的喷雾和燃烧过程可视化与火焰温度测量使用双色光学高温计，以了解发生在分裂喷射策略的燃烧现象。光学研究的结果表明，不同的低温燃烧操作条件下产生类似的低水平的“发动机排出”的烟雾排放有很大不同的历史烟尘的形成和烟尘氧化。在给定的进气压力下，进气氧质量分数的增加降低了总碳氢化合物排放量和总指示燃料消耗率，而更高的进气压力进一步降低了它们。虽然从第二次喷射事件发生了显着的碳烟形成，大部分的碳烟随后被氧化，因为一个略高的火焰温度和略高的氧气浓度比单次喷射高废气再循环低温燃烧。较高的喷射压力对排放和总指示燃料消耗率没有任何显著影响。
This paper shows that a split-fuel-injection strategy can achieve robust, near-zero smoke and nitrogen oxide emissions at reduced exhaust gas recirculation levels under low-temperature combustion conditions. The overall objective of the work was to investigate the sensitivity (in terms of the engine emissions and the fuel economy) of a 50:50 (by mass) split-injection strategy to variations in the key engine operating parameters. Experiments were performed at operating conditions corresponding to a gross indicated mean effective pressure of 500 kPa at an engine speed of 1500 r/min in a 0.51 l single-cylinder high-speed direct-injection diesel engine. The paper presents the effects of different relative fuel injection timings at a variable intake oxygen mass fraction (10.5% and 12%) at a constant intake pressure (120 kPa, absolute) on the smoke, total hydrocarbon and carbon monoxide emissions with the split-main-injection strategy. The effects of a variable fuel injection pressure (90 MPa and 110 MPa) on diesel low-temperature combustion with split injection are also reported, as are the effect of an increased intake pressure (150 kPa, absolute). The combined effects of the operating parameters and the fuel injection timing on the smoke, nitrogen oxide, total hydrocarbon and carbon monoxide emissions and the gross indicated specific fuel consumption are described. For selected operating conditions, the cycle-resolved spray and combustion processes are visualized together with the flame temperature measurement using two-colour optical pyrometry to understand the combustion phenomena occurring in the split-injection strategy. The results of the optical studies show that different low-temperature combustion operating conditions producing similarly low levels of ‘engine-out’ smoke emissions have substantially different histories of soot formation and soot oxidation. An increase in the intake oxygen mass fraction reduced the total hydrocarbon emissions and the gross indicated specific fuel consumption at a given intake pressure, while a higher intake pressure reduced them further. Although significant soot formation took place from the second injection event, the majority of the soot was subsequently oxidized because of a slightly higher flame temperature and slightly higher oxygen concentration than in single-injection high-exhaust-gas-recirculation low-temperature combustion. A higher injection pressure did not have any significant effect on the emissions and the gross indicated specific fuel consumption.