可变截面涡轮增压器与废气再循环

Effects of VGT/EGR on Emissions from Diesel Engine

摘要:

以一台重型柴油机为试验对象，研究可变截面涡轮增压器(VGT)和废气再循环(EGR)阀门开度对柴油机增压比、空燃比、燃油消耗率及NOx，CO，HC，CO2和烟度等排放特性的影响.研究结果表明，随着EGR阀门开度的增大，增压比、空燃比降低，经济性变差.EGR阀门开度和VGT阀门开度对NOx排放影响很大，随EGR阀门开度和VGT阀门开度增大,NOx排放的体积分数显著降低，但HC，CO，CO2的体积分数和烟度升高.为实现降低NOx排放的同时控制燃油消耗率和烟度的升高，可在中等负荷时选择EGR阀门开度50%、VGT阀门开度45%的控制策略；在高负荷时选择EGR阀门开度75%、VGT阀门开度55%的控制策略.

Abstract:

The effects of variable geometry turbine(VGT)/ exhaust gas recirculation (EGR) on pressure ratio, airfuel ratio, specific fuel consumption, and emissions of NOx, CO, HC, CO2 and smoke from a heavy duty diesel engine have been investigated. The results show that pressure ratio and airfuel ratio decrease, and fuel economy deteriorates with the increase of the opening of the EGR valve. NOx emission can be strongly affected by the opening of the EGR valve and VGT valve. NOx emission can be greatly reduced by increasing the opening of the EGR valve and VGT valve, and there is good logarithmic relationship between decline of volume concentration of NOx and the opening of EGR valve. However, HC, CO, CO2 and smoke emissions are increased. In order to lower NOx emission, while effectively controlling fuel economy and smoke emission, 50% of the opening of the EGR valve combined with 45% of the opening of the VGT valve is suitable at medium load, and 75% of the opening of the EGR valve combined with 55% of the opening of the VGT valve is suitable at high load.