极寒条件下含氧燃料对柴油机冷起动特性的影响

Effects of Oxygenated Fuels on Cold Start Characteristics of Diesel Engines Under Extreme Cold Conditions

针对柴油机存在低温冷起动困难甚至无法起动的问题,基于起动/发电机集成一体化技术柴油机,在高原低温发动机冷起动试验舱,研究-50号柴油A0(氧质量分数为0%)、A1(氧质量分数为2.05%)和A2(氧质量分数为4.40%)燃料在-43℃下对柴油机冷起动过程的影响和燃烧特性分析.结果表明:相比A0纯柴油,燃用A1、A2含氧燃料起动时间分别缩短了36.64%和42.71%;起动累计油量分别降低47.8%和60.6%;怠速运行前60 s内转速波动率分别降低25.3%和43.8%.燃用燃料氧质量分数越高,起动燃烧首循环的缸内压力、燃烧放热率、缸内燃烧温度和缸内压力升高率峰值越高,且燃烧重心前移,燃烧持续期越短;起动转速上升过程循环数越少,平均最大缸内压力越大,起动过程燃烧稳定性越好.

In order to solve the problem of cold start struggling and failing of engine,comparative experiments were conducted on a diesel engine with integrated starting/generator technology fueled with-50#diesel A0(fuel oxygen content 0%),A1(fuel oxygen content 2.05%)and A2(fuel oxygen content 4.40%).Experimental data were collected on an engine cold start test cell of high plateau conditions at-43℃.Effects of different fuel oxygen contents on the processes and combustion of the diesel engine under cold start conditions were examined.The results show that comparing with A0,starting times of the diesel engine fueled with A1 and A2 are shortened by 36.64%and 42.71%respectively.The amount of fuel consumption during cold start periods is reduced by 47.8%and 60.6%respectively and the speed fluctuation rate is reduced by 25.3%and 43.8%respectively in the first 60 s of idle operation.With the increases of fuel oxygen content,the in-cylinder combustion temperature and in-cylinder pressure of the first diesel cycle,the heat release rate and the peak pressure rise rate all are increased.The CA 50 is advanced and the combustion duration is shortened.And the lower the number of cycles is during the starting speed rise,the higher the average maximum cylinder pressure,and the better the combustion stability during the starting process.