EGR冷却温度对重型柴油机性能及排放的影响

以一台配有废气再循环(exhaust gas recirculation,EGR)冷却系统和可变几何截面涡轮增压器的高压共轨重型柴油机作为研究对象,进行了EGR冷却温度对柴油机性能及排放影响的台架试验研究。结果表明:随着EGR冷却温度降低,柴油机燃油消耗率、烟度和NOx排放均持续降低。而EGR冷却温度每降低1℃,柴油机燃油消耗率、烟度和NOx排放在不同转速、负荷下降幅差异明显。燃油消耗率在中等转速、低负荷工况降幅最大,NOx排放和烟度在高转速、低负荷工况下降幅最大;在考虑到EGR冷却系统消耗的能量后,可以通过计算得到理论燃油消耗率。在兼顾燃油消耗率和排放性的原则下得到了各工况下EGR相对最优冷却温度,而所得到的相对最优EGR冷却温度正是各个试验工况下理论燃油消耗率最低的温度。

Influence of EGR Cooled-Gas Temperature on Performance and Emissions of a Heavy Duty Diesel Engine

A common rail heavy duty diesel engine with exhaust gas recirculation(EGR) cooler and variable geometry turbocharger was used to study the influence of EGR cooled-gas temperature on engine performance and exhaust emissions by bench test. The results show that the fuel consumption, NOx and smoke decrease when the EGR cooled-gas temperature declines. With every one degree decrease in EGR cooled-gas temperature, the reductions of fuel consumption, NOx and smoke at different operating conditions are quite different. At medium speed with low load, the fuel consumption reduces most; at high speed with low load, the NOx and smoke decreases most. Taking the energy consumption by EGR cooler into consideration, the actual fuel consumption can be calculated. In the principle of as low actual fuel consumption and low emissions as possible, the optimized EGR cooled-gas temperatures at which the actual fuel consumptions are the lowest can be determined at different operating conditions.