正丁醇燃料特性对柴油机低温燃烧影响的机理

Mechanism of Effects of n-Butanol Properties on Low Temperature Combustion in a Diesel Engine

在一台单缸柴油机上,将20%体积分数的正庚烷、异辛烷和正丁醇分别与柴油进行掺混燃烧,研究了正丁醇沸点、燃料组分、十六烷值和含氧特性等理化特性对柴油机低温燃烧(LTC)的影响机理.结果表明,十六烷值是影响LTC燃烧特性的主导参数,柴油+正庚烷和柴油+异辛烷的燃烧特性分别与纯柴油和柴油+正丁醇接近.碳烟排放上,柴油+正庚烷与纯柴油差别很小,表明在20%掺混条件下,物理特性和燃料组分对LTC碳烟排放影响较小;柴油+异辛烷的碳烟排放较纯柴油降低明显,表明十六烷值是影响LTC碳烟排放的重要因素;柴油+正丁醇的碳烟排放比柴油+异辛烷有较大降低,表明正丁醇含氧特性对改善LTC碳烟排放具有重要作用.燃料理化特性对NOx、CO和HC等气体污染物排放影响较小.

The mechanism of effects of boiling point, fuel composition, cetane number, and oxygenated characteristic of n-butanol on low temperature combustion （LTC）were studied on a diesel engine. 20% volume addition of n-heptane, iso-octane and n-butanol is separately blended with diesel fuel. Results show that the combustion characteristics of n-heptane-diesel blend and iso-octane-diesel blend are respectively close to those of pure diesel and n-butanol-diesel blend, reflecting a dominant role of cetane number on LTC combustion. The difference in soot emission between n-heptane-diesel blend and diesel is small, suggesting small role of fuel physical property and composition on soot emission. Remarkable reduction of soot emission with iso-octane-diesel blend compared with that of pure diesel reveals the strong influence of cetane number on soot emission. Large reduction of soot emission with n-butanol-diesel blend compared with that of iso-octane-diesel blend suggests that oxygenated characteristic is favorable to decrease soot emission. Fuel property shows little influence on gasous emissions like NOx, CO and HC in this studv.