转速和冷却液温度对汽油HCCI燃烧特性和排放的影响

Effect of rotation speed and coolant temperature on combustion characteristic and emissions of gasoline HCCI

为研究转速和冷却液温度对汽油HCCI燃烧特性和排放的影响,在一台改造的试验发动机上进行相关的试验.结果表明:随着转速的增加,转速升高,缸内峰值压力升高,缸内温度变化不大,只是最高温度对应的曲轴转角提前,燃烧始点对转速不敏感,燃烧持续期缩短;当冷却液温度升高,缸内峰值压力和压力升高率升高,瞬时放热率增大,缸内峰值温度和燃烧始点基本不受冷却液温度变化的影响,冷却液温度升高,缸内向外散失的热量减少,燃烧持续期缩短,HC和CO排放减少,由于缸内温度一直不是很高,不利于NOx排放生成,在本次试验中测得的排放为零.

The test was conducted on a modified engine fuelled with gasoline to study the effects the rotation speed and coolant temperature on combustion characteristic and emissions of gasoline HCCI. The resuits showed that with the increase of rotation, the pressure in cylinder raised, temperature in cylinder changed little,corresponding crank angle for peak temperature was advanced,the combustion start point of HCCI was insensitive to rotation speed and combustion duration shortened. As the coolant temperature in- creased, peak pressure and rate of pressure rise rate in cylinder raised, the instantaneous heat release rate increased,peak temperature in cylinder basically insusceptible to the change of coolant temperature, the heat loss in cylinder decreased,combustion duration is shortened and HC and CO emissions reduced. Constantly low temperature in cylinder was against NOx formation with zero NOx emissions in the test.