重型柴油机冷EGR与VGT耦合优化试验研究

以1台重型柴油机为试验对象,基于台架试验结果,通过建立数学模型和评价标准,对各个工况下的EGR和VGT阀门开度组合进行优化。经各评价标准优化结果的比较,选取折中NOx排放和烟度的标准作为最优方案,对其优化结果进行分析可知:相同转速下,随着负荷的增大,EGR阀门开度先增大后减小;中等负荷下,VGT阀门开度较小,随着转速的升高,阀门开度逐渐增大;NOx及CO排放整体较低,大负荷和高转速工况下NOx排放显著提升,低速大负荷工况下CO排放严重升高;中等负荷下,排气烟度极低,但低速大负荷工况下烟度迅速升高。

Experimental Study on Coupling Optimization of Cold EGR and VGT for Heavy-Duty Diesel Engine

Based on the bench test results of a heavy-duty diesel engine,the valve opening of EGR and VGT were optimized by establishing the mathematical model and evaluation criteria.By comparing the optimization results of each evaluation criterion,the criterion for a balance between the NOx and smoke emissions was selected as the optimal scheme.According to theoptimization results of optimal scheme,the valve opening of EGR increased first and then decreased with the increase of load at the same speed.Under medium load,the valve opening of VGT was small and increased gradually with the increase of rotational speed.The total emissions of NOx and CO were low,the NOx emission increased significantly under highload and high speed condition and the CO emission increased greatly under low speed and high load condition.The smoke emission was very low under medium load,but increased rapidly under low speed and high load condition.