EGR率和预喷时刻对柴油机NO_x和CO排放的影响

Effect of EGR Rate and Pilot Injection Timing on NO_x and CO Emissions of Diesel Engine

选用某四缸电控高压共轨柴油机进行试验,研究不同EGR率和预喷提前角对柴油机NO_x和CO排放量的影响。在测试转速2 500 r/min、扭矩100 N·m工况下,EGR率分别为0%、50%、60%和70%,预喷提前角分别为上止点前10°、20°、30°和40°时,对NO_x和CO的排放量进行了测量。结果表明:当预喷提前角相同时,NO_x和CO排放量均随EGR率的增大而减小。当EGR率相同时,CO排放量随预喷提前角的增大开始缓慢变化,然后迅速增大;NO_x排放量随着预喷提前角的增大开始变化不大,然后迅速减小,再缓慢变化。

Taking a four-cylinder electronically controlled high pressure common rail diesel engine as a test object, the paper studies the effects of different EGR rates and pilot injection time on NOx and CO emissions of diesel engine, measures the amount of NOx and CO under conditions that EGR rate is set as 0,50% ,60% and 70% ,the pilot time is set as 10°BTDC,20°BTDC,30°BTDC and 40°BTDC, and the engine rotating speed is 2 500 r/min, torque is 100 N · m. The experimental result shows that if the pilot injection time is the same, both NO, and CO emissions decrease as the EGR rate increases;if the EGR rate is the same, CO emissions vary slowly at first and then increase quickly as the pilot injection time is advanced,and NOx emissions vary slightly in the beginning, then decrease quickly, afterwards vary slowly as the pilot injection time is advanced. So selecting the appropriate EGR rate and pilot injection time can significantly reduce NOx and CO emissions of diesel engines.