废气再循环阀开度对柴油机排放特性的影响

Exhaust Gas Recirculation (EGR) system is an important means to reduce the NOx emission of diesel engine, but it will have different degrees of impact on the emission of other pollutants. Based on the engine bench, the steady-state orthogonal tests of EGR and variable geometry turbocharger (VGT) were carried out on a high-pressure common rail heavy-duty diesel engine, and the influence of EGR valve opening on diesel engine NOx, CO, CO2, soot, and other pollutants under steady-state conditions was investigated. The results shows that the NOx emission decreases with the increase of EGR valve opening. When the EGR valve opening exceeds 50%, the NOx emission decreases slowly. The CO emission of diesel engine increases with the increase of EGR valve opening, which is obviously under high load conditions; EGR has little effect on CO2 emissions under low and medium load conditions of diesel engine, while CO2 emission increases significantly with the increase of EGR valve opening under high load conditions. The exhaust smoke intensity increases with the increase of EGR valve opening, especially when the EGR valve opening exceeds 50%. When the EGR valve is fully open, the exhaust smoke increases by an average of 146.6% compared with that without EGR.