EGR和VNT的匹配对增压柴油机排放的影响

通过可变喷嘴增压器(VNT)和废气再循环(EGR)系统的匹配试验,考察了VNT对发动机排气和进气的压差以及EGR率的影响规律,研究了降低四缸增压柴油机的排放问题。试验结果表明,EGR系统能在不改变柴油机动力性、经济性和烟度排放的基础上,使柴油机NOx排放量降低20%~47%。VNT通过调节废气涡轮增压器涡前压气后的压差,可将EGR率提高2%~12%。

Synergic effects of EGR and VNT on exhaust emissions from turbocharged diesel engine

In order to reduce the exhaust emissions from a 4-cylinder turbocharged automotive diesel engine,the synergy of the variable nozzle turbocharger(VNT) and the exhaust gas recirculation(EGR) was studied experimentally to reveal the effects of the VNT on the EGR driving pressure difference and the achievable EGR rate.The test results showed that the developed EGR system reduces the engine NO_x emission by 20%~47% without the penalty on the engine power output,the fuel economy and the exhaust smoke.The EGR rate could be increased by 2%~12% through regulating the difference between the gas pressure before the VNT and the air pressure after the VNT by means of VNT adjustment.