在4B26增压柴油机上，以进气管电控喷射的方式掺入甲醇，实现甲醇/柴油双燃料的燃烧。采用废气再循环技术拓宽高比例甲醇双燃料柴油机的工况范围，研究EGR对燃烧过程的影响规律。结果表明：适当的EGR率可以显著降低燃烧初期时的燃烧反应速度和加速度，缸内燃烧压力振荡明显减弱。随着EGR率的增加，甲醇/柴油预混合燃烧量减少，滞燃期缩短，燃烧持续期延长，燃烧最高温度降低；原甲醇/柴油双燃料燃烧放热以预混放热为主；引入EGR后，预混放热量减少，扩散放热量增加。随着EGR率的增加，放热率峰值降低；在相同工况下，保持掺混48%甲醇不变时，甲醇/柴油双燃料发动机的指示热效率随EGR率的增加而降低。%Methanol/diesel dual fuel combustion is realized on a turbocharged diesel engine 4B26 with methanol blended in by electronically controlled intake port injection. Exhaust gas recirculation ( EGR) technology is adopted to extend the working range of dual fuel diesel engine with high proportion of methanol with its effects on combustion process studied. The results show that an appropriate EGR rate can significantly reduce the speed and acceleration of combustion reaction at initial stage and weaken the oscillation of in-cylinder combustion pressure. With the increase in EGR rate, the volume of premixed combustion of methanol/diesel blend reduces, ignition delay period shortens, combustion duration prolongs and the combustion temperature peak lowers. The main parts of heat release is premixed one for methanol/diesel dual fuel combustion in nature, but with EGR introduced, premixed heat release reduces, diffusion heat release increases, and the peak heat release rate lowers when EGR rate increa-ses. In the same working condition with a fixed methanol proportion of 48%, the indicated thermal efficiency of methanol/diesel duel fuel engine lowers with the increase of EGR rate.
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