进气氧浓度对柴油机燃烧过程影响的仿真研究
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摘要
为分析进气氧浓度对柴油机燃烧的影响,通过调节进气氮氧比控制进气氧浓度,应用计算流体力学(CFD)软件FIRE对不同进气氧浓度下柴油机燃烧过程进行了三维仿真研究。研究结果表明:进气氧浓度影响缸内混合气质量,进气氧浓度降低,缸内浓混合气增加,扩散燃烧阶段放热速率降低。随着进气氧浓度降低,缸内最高压力和平均温度降低,柴油机燃烧品质变差。富氧燃烧时柴油机NOx排放升高,碳烟排放降低;部分负荷时,进气氧浓度降低,NOx和碳烟排放均降低。
In order to investigate the effect of intake air oxygen concentration on the combustion process in diesel engine,computation fluid dynamics( CFD) software FIRE is used to simulate the combustion process in terms of the ratio of oxygen and nitrogen in intake air. The results show that intake air oxygen concentration affects the quality of fuel-air mixture. With the decrease in intake air oxygen concentration,the rich fuel-air mixture increases,which leads to a decrease in heat release rate in the stage of diffusion combustion. The decrease in intake air oxygen concentration reduces the in-cylinder peak pressure and combustion temperature,and the quality of combustion becomes worse. The oxygen-enriched combustion leads to a remarkable increase in NOxemission and a decrease in soot emission; with a decrease in intake air oxygen concentration at part load,both NOxand soot emissions decrease.
In order to investigate the effect of intake air oxygen concentration on the combustion process in diesel engine,computation fluid dynamics( CFD) software FIRE is used to simulate the combustion process in terms of the ratio of oxygen and nitrogen in intake air. The results show that intake air oxygen concentration affects the quality of fuel-air mixture. With the decrease in intake air oxygen concentration,the rich fuel-air mixture increases,which leads to a decrease in heat release rate in the stage of diffusion combustion. The decrease in intake air oxygen concentration reduces the in-cylinder peak pressure and combustion temperature,and the quality of combustion becomes worse. The oxygen-enriched combustion leads to a remarkable increase in NOxemission and a decrease in soot emission; with a decrease in intake air oxygen concentration at part load,both NOxand soot emissions decrease.
引文
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[2]隆愈强.不同氮氧组分进气发动机性能及排放试验研究[D].长春:吉林大学,2009.LONG Yu-qiang.Experiment investigation of combustion and emission in engine by variable intake-air composition of oxygen and nitrogen[D].Changchun:Jilin University,2009.(in Chinese)
[3]张全长,尧命发,郑尊清,等.进气氧浓度对柴油机低温燃烧影响的实验研究[J].内燃机学报,2009,27(4):298-305.ZHANG Quan-chang,YAO Ming-fa,ZHENG Zun-qing,et al.The effects of intake oxygen concentration on the combustion and emission characteristics of the diesel[J].Transactions of CSICE,2009,27(4):298-305.(in Chinese)
[4]ZHENG Z L,YAO M F.Mechanism of oxygen concentration effects on combustion process and emissions of diesel engine[J].Energy Fuels,2009,23(12):5835-5845.
[5]姚春德,刘增勇,何邦全.进气氮气含量对柴油机混合气形成于燃烧过程的影响[J].燃烧科学与技术,2002,8(3):233-237.YAO Chun-de,LIU Zeng-yong,HE Bang-quan,et al.Influence of intake air mixed with N2on combustion process in a diesel engine[J].Journal of Combustion Science and Technology,2002,8(3):233-237.(in Chinese)
[6]张韦.柴油机富氧燃烧及排放的实验研究与理论计算[D].天津:天津大学,2010.ZHANG Wei.Experiment and calculation on oxygen-enriched combustion and control of emissions of diesel engine[D].Tianjin:Tianjin University,2010.(in Chinese)
[7]肖广飞,乔信起,孙恺,等.膜法富氧进气改善直喷式柴油机的起动性能[J].上海交通大学学报,2007,41(10):1629-1632.XIAO Guang-fei,QIAO Xin-qi,SUN Kai,et al.Improvement on starting performance of a DI diesel engine by using membranebased oxygen-enriched intake air[J].Journal of Shanghai Jiaotong University,2007,41(10):1629-1632.(in Chinese)
[8]高荣刚,李国岫,虞育松,等.高原环境对柴油机燃烧过程的仿真研究[J].兵工学报,2012,33(12):1448-1454.GAO Rong-gang,LI Guo-xiu,YU Yu-song,et al.Multi-dimensional simulation for the effect of plateau environment on combustion process in diesel engine[J].Acta Armamentarii,2012,33(12):1448-1454.(in Chinese)
[9]石秀勇.喷油规律对柴油机性能与排放的影响研究[D].济南:山东大学,2007.SHI Xiu-yong.Research of injection rate on diesel engine performance and emissions[D].Jinan:Shandong University,2007.(in Chinese)
[10]韩永强,赵佳佳,张亮,等.放热率对效率的影响及对HCCI燃烧负荷限制评测[J].内燃机学报,2008,26(2):121-127.HAN Yong-qiang,ZHAO jia-jia,ZHANG Liang,et al.Heat release rate on the efficiency and evaluation of HCCI combustion load limit[J].Transactions of CSICE,2008,26(2):121-127.(in Chinese)
[11]安晓辉,刘波澜,张付军,等.基于氧浓度的EGR对柴油机性能影响的仿真[J].内燃机学报,2013,31(2):115-119.AN Xiao-hui,LIU Bo-lan,ZHANG Fu-jun,et al.Simulation of the effect of intake charge oxygen concentration based EGR on diesel engine performance[J].Transactions of CSICE,2013,31(2):115-119.(in Chinese)