在研究不同温度、含水量和高碳醇对乙醇/柴油互溶性影响的基础上,将柴油、乙醇和正己醇以20∶60∶20体积比混合作为测试燃料,开展了不同含水乙醇及喷油压力下的柴油机燃烧和排放试验.结果表明:含水量的增加和温度的降低会引起乙醇/柴油互溶性变差,利用不同高碳醇助溶剂均可解决混合燃料相分离现象.乙醇中含水量的小幅升高会使滞燃期延长,缸内压力和放热率峰值升高,同时能降低氮氧化物(NOx)和总碳氢化合物(THC)排放,CO排放基本保持不变,但负荷较低时会使CO排放升高.在含水乙醇/柴油燃料应用过程中,理想的喷油压力边界范围将会缩窄:低喷油压力易使燃烧恶化,而高喷油压力容易导致柴油机工作粗暴,且NOx与CO排放也呈上升趋势.%To solve the solubility problem of ethanol/diesel blend,the influences of different temperatures,water contents and higher alcohol additives on fuel solubility were investigated.Based on this research,an experimental study on the effects of hydrous ethanol and injection pressure on diesel engine performance and exhaust emission behaviors were conducted by mixing the blend of diesel,ethanol and n-hexanol with a volume ratio of 20 ∶ 60 ∶ 20.The results show that high water-containing and low temperature break the stable single-phase of ethanol/diesel,but adding high carbon alcohol additives can resolve this phenomena.The engine tests demonstrate that a small reduced water content in ethanol leads to a prolonged ignition delay,higher combustion pressure and heat release rate.Meanwhile,NOx and THC emissions tend to reduce with a rise of the water content,while CO emissions are nearly the same except for low load operations,where CO emissions increase.It is also found that the boundaries of feasible injection pressure will be narrowed during the application of the blends of hydrous ethanol and diesel.On one hand,lower injection pressure can worsen the combustion process due to bad air/fuel mixing.On the other hand,higher injection pressure will be easy to result in roughness combustion and higher NOx and CO emissions.
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