柴油喷射参数对高废气再循环(EGR)率下生物质气/柴油双燃料发动机燃烧的影响

Effects of Injection Parameters on Combustion Characteristics of Biogas-Diesel Dual Fuel Engine with High EGR Rate

通过调节柴油主喷正时以及预喷比,对高EGR率下双燃料燃烧模式优化,探究主喷正时、预喷比对高EGR率下生物质气/柴油双燃料发动机燃烧模式的影响。首先改变主喷正时进行对比试验,选取4个主喷正时,分别为上止点前3°、5°、7°和9°曲轴转角,预喷比取40%;然后选取40%、50%和60%3个预喷比进行对比试验,主喷正时取上止点前5°曲轴转角。研究表明随着主喷正时的提前,燃烧相位提前,热效率提高,碳氢(HC)和一氧化碳(CO)排放降低,而氮氧化物(NOx)升高;预喷比增大时燃烧提前,热效率略有升高,并且在大预喷比条件下碳烟排放较高。

The effects of main injection timing and we-injection ratio of diesel fuel on the combustion mode for biogas/diesel dual-fuel engines were investigated respectively by adjusting these two parameters and optimizing the combustion mode at a high EGR rate. First, the tests were carried out and cornpaled at four test points of different main injection timings （3°CA,5°CA,7°CA, 9°CA BTDC） with a pie-injection ratio of 40%. Then, similar tests wele made with various pie-injection ratios （40% ,50% , 60% ） at fixed main injection timing （5-CA BTDC）. The research results indicate that the combustion phase advances, thermal efficiency and NOx emissions increase, and the emissions of HC and CO decrease under the conditions of advanced main injection timings. It is also shown that the combustion phase advances with the increase of the pre-injection ratio, resulting in slightly increased thermal efficiency. Under the conditions of higher pie-injection ratio, higher soot emission is obtained.