柴油机燃用柴油/甲醇混合燃料时的性能与排放研究

通过添加助溶剂形成一种稳定的柴油／甲醇混合燃料，并开展了柴油机燃用此混合燃料的性能与排放研究。研究结果表明：发动机热效率和柴油等热值燃油消耗率随混合燃料中甲醇含量的增加而改善，这是由于预混燃烧量的增加，燃料富氧以及扩散燃烧的改善所致。适当增加供油提前角可使柴油／甲醇混合燃料发动机热效率提高。燃用柴油／甲醇混合燃料可显著降低发动机CO和烟度，而对碳氢排放影响不大；在相同平均有效压力的条件下，N0x随甲醇含量的增加而增加，添加甲醇对N0x的影响在大负荷下更为明显。柴油／甲醇混合燃料燃烧时存在一个较为平坦的N0x／烟度关系曲线。

Performance and Emissions of a DI Diesel Engine Operating on Diesel/Methanol Blends

A stabilized diesel/methanol blend was realized and the study on the performance and emissions of the diesel/methanol blend was conducted in a DI engine.The study showed that the thermal efficiency of engine increases and the diesel equivalent brake specific fuel consumption (bsfc) decreased with the increase in methanol mass fraction for diesel/methanol blends due to an increased fraction of premixed combustion phase,an oxygen enrichment and an improvement in diffusive combustion phase.Further advancement of fuel delivery advance angle would achieve a better engine thermal efficiency when operating on the diesel/methanol blends.Remarkable reduction in the exhaust CO and smoke could be achieved when operating on the diesel/methanol blend.Exhaust HC gave less variation with the addition of methanol in diesel fuel.NO_x increased with the increase of methanol mass addition and methanol addition in diesel fuel was found to have a strong influence on NO_x concentration at the high engine load rather than at the low engine load,and a flat NO_x/Smoke trade-off curve is observed in the combustion of diesel/methanol blends.