The effects of split injections on high exhaust gas recirculation low-temperature diesel engine combustion
The effects of split injections on high exhaust gas recirculation low-temperature diesel engine combustion
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DOI：
10.1177/1468087412450987
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发表时间：
2013-02
影响因子：
2.5
通讯作者：
A. Sarangi;C. P. Garner;G. McTaggart-Cowan;M. Davy;E. Wahab;M. Peckham
中科院分区：
文献类型：
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作者：
A. Sarangi;C. P. Garner;G. McTaggart-Cowan;M. Davy;E. Wahab;M. Peckham
柴油机通过采用高水平的废气再循环实现低温燃烧，可以同时减少氮氧化物和烟度的排放。然而，每循环单次燃料喷射柴油机低温燃烧的特征还在于高燃料消耗和高总未燃碳氢化合物和一氧化碳排放。这项工作的重点是调查潜在的分裂（50/50）的主要燃料喷射策略，以减少烟雾，总未燃碳氢化合物和一氧化碳排放量的废气再循环水平低于那些需要实现单次喷射柴油机低温燃烧在中等负荷，中等速度的操作条件。在一台0.51升单缸高速直喷柴油机上，在平均指示压力为500 kPa的工况下，以1500 r/min的转速进行了试验。在此负载下，需要62%的废气再循环水平来实现接近零的氮氧化物和烟雾排放，但这导致热效率的不可接受的降低以及高的总未燃烧碳氢化合物和一氧化碳排放。这项工作比较了在排气再循环水平为52%（按体积）的情况下的分段燃料喷射与在排气再循环水平为52%和62%的情况下的单次喷射的效果。结果表明，废气再循环率和分次喷射的组合效应可以实现接近零的氮氧化物，具有良好的热效率和总未燃碳氢化合物和一氧化碳排放量远低于62%的废气再循环。此时单次喷射会导致过量的烟雾，通过分次喷射策略可以减少75%以上。这些结果是特别相关的，因为它们证明了具有可接受的热效率和实际废气再循环水平的发动机操作的氮氧化物排放非常低。
Diesel engine emissions of oxides of nitrogen and smoke can be reduced simultaneously through the use of high levels of exhaust gas recirculation to achieve low-temperature combustion. However, single fuel injection per cycle diesel low-temperature combustion is also characterized by high fuel consumption and high total unburned hydrocarbons and carbon monoxide emissions. This work focuses on investigating the potential of a split (50/50) main fuel-injection strategy to reduce smoke, total unburned hydrocarbons and carbon monoxide emissions at exhaust gas recirculation levels lower than those required to achieve single-injection diesel low-temperature combustion at a medium-load, medium-speed operating condition. Experiments were performed on a 0.51 l single-cylinder high-speed direct-injection diesel engine running at 1500 r/min at an operating condition corresponding to a gross indicated mean effective pressure of 500 kPa. At this load, exhaust gas recirculation levels of 62% are needed to realize near-zero nitrogen oxide and smoke emissions, but this leads to an unacceptable reduction in thermal efficiency as well as high total unburned hydrocarbons and carbon monoxide emissions. This work compares the effects of split fuel injections at an exhaust gas recirculation level of 52% by volume to those from single injections at exhaust gas recirculation levels of 52% and 62%. The results demonstrate that the combined effects of exhaust gas recirculation rate and split injections can achieve near-zero nitrogen oxide with good thermal efficiency and total unburned hydrocarbons and carbon monoxide emissions much lower than at 62% exhaust gas recirculation. Single injection at this point results in excessive smoke, which can be reduced by over 75% through the split-injection strategy. These results are particularly relevant as they demonstrate very low nitrogen oxide emissions from an engine operation with acceptable thermal efficiency and at practical exhaust gas recirculation levels.