DTBP改性汽油PPCI燃烧与排放特性的试验研究

Experimental Research on PPCI Combustion and Emissions with DTBP/Gasoline Blends

在单缸柴油机上研究了不同比例十六烷值增强剂二叔丁基过氧化物(DTBP)/汽油改性燃料对部分预混压燃(PPCI)燃烧与排放的影响。研究结果表明:DTBP能拓展汽油PPCI运行工况;随着DTBP含量的增加,滞燃期缩短,燃烧相位CA50靠近上止点,燃烧放热集中,缸内温度升高,最大压力升高率升高,预混燃烧所占比例减小;随着DTBP含量的增加,NO排放升高,未燃HC和CO排放降低,有效热效率提高。并研究了DTBP质量分数为1%时,喷油时刻与废气再循环(EGR)对PPCI燃烧与排放特性的影响。研究结果表明:在喷油时刻延迟到曲轴转角为上止点前5°时,NO排放大幅降低,未燃HC和CO排放有所升高,较高负荷时有效热效率提高;EGR率20%时,有效热效率基本无变化,同时NO排放降低了60%,未燃HC排放降低了20%,CO排放提高了30%。

The influence of different ratios of cetane number improver-DTBP/gasoline blends on PPCI combustion and exhaust emissions was studied on a single-cylinder engine. The experimental results show that DTBP could expand engine operating range. The increased DTBP ratio would make ignition delay decrease, CA50 get close to TDC, heat release concentrate, exhaust gas temperature increase, maximum pressure rise rate increase and premixed combustion ratio decrease; NO emission increase, UHC and CO emissions reduce, while effective thermal efficiency increase. Further experiments were carried out with 1% of DTBP mass fraction to find out the impacts of injection timing and EGR ratio on PPCI combustion and exhaust emissions. The experimental results show that when the injection timing was adjusted to 5°crank angle BTDC, NO emission reduced dramatically, UHC and CO emissions increased slightly, and effective thermal efficiency increased slightly at moderate toad （0. 237 MPa BMEP）, while NO emission reduced by 60%, UHC emission reduced by 20%, and CO emission increased by 30%, but effective thermal efficiency remained almost constant together with 20% EGR.