重型柴油机高压EGR系统管路设计仿真研究

Simulation Investigation on Design of High Pressure EGR System Pipeline in Heavy-Duty Diesel Engine

采用一维发动机工作过程计算软件GT-Power,建立了2种不同管路布置的高压EGR系统仿真模型,模拟研究了其对柴油机性能和排放的影响。研究结果表明:隔开取气的高压EGR系统对排气脉冲能量利用较好,可以提高废气再循环的引入能力(特别是在实现EGR比较困难的低转速大负荷工况),并改善NOx排放和燃油消耗率之间的折中关系;相对单级增压,二级增压采用隔开取气布置的高压EGR系统对性能和排放的改善效果减弱;通过优化二级增压隔开取气方式的EGR管路结构尺寸后,能够进一步改善柴油机的性能和排放。

Two simulation models were built up by GT-Power software package and used to study effects of different pipeline layout of high pressure EGR boost system on performance and emissions of heavy duty diesel engine. Simulation results show that the separated high pressure EGR boost system, better using exhaust gas pulsing energy can enhance the ability of EGR introduction, particularly under the condition of low speed high load difficult to introduce exhaust gas, and achieve much better trade-off between NOx and fuel economy. When applying two-stage turbocharging, difference between the two high pressure EGR boost systems becomes quite small. Engine performance and emissions can be further improved by optimizing the EGR pipeline of separated high pressure EGR boost system.