排气和中冷前进气节流对柴油机性能和排放特性的影响

The Effects of Exhaust Throttling and Throttling before Intercooler on Engine Performance and Emission Characteristics

通过先后分开调节安装在涡轮机后和中冷前的两个蝶形阀,来模拟研究排气节流和中冷前进气节流对发动机外特性性能及排放的影响。试验结果表明:增加排气节流后,低速时,发动机性能和排放特性变化较小;而中高速时,发动机排气背压和排气温度会明显升高,动力性和燃油经济性也会明显恶化,CO和THC比排放及核膜态和聚集态颗粒总数量浓度都明显增加,氮氧化物(NOx)比排放明显降低。增加中冷前进气节流后,发动机的动力性和燃油经济性只略微变差,变化很小,但在低速时排气温度明显升高。中冷前进气节流增加后对排放影响较大,尽管CO比排放只是略微升高,但THC比排放和核膜态颗粒总数量浓度排放都明显降低,在最大转矩转速附近对应超细颗粒总数量浓度和聚集态颗粒总数量浓度排放也明显降低。

By adjusting two valves, one after turbine and the other before intercooler respectively, the effects of exhaust throttling and intake throttling before intercooler on engine performance and emission characteristics at full load were simulated and researched. The results show that the increase of exhaust throttling makes the engine performance and emission characteristics change a little at low engine speed, but at high speed, it makes the exhaust back pressure and exhaust temperature increase significantly. These allow to have worse engine power and economy performance with the significant increase of CO and THC emissions and also the number concentration of both nucleation mode and accumulation mode particles, but with a slight decrease of NOx emissions. While the increase of intake throttling loss makes the exhaust temperatures rise significantly at low speed, but at all speeds, it makes the engine power and economy performance turn worse marginally. These allow to have bad CO emissions with the significant decrease of THC emissions and the number of nucleation mode particles. At maximum torque speed, the corresponding total number of particles and the number of accumulation mode particles will drop.