臭氧对天然气均质压缩燃烧的影响

Effect of Ozone on Natural Gas Homogeneous Compression Combustion

针对均质压燃(homogeneous charge compression ignition,HCCI)技术仍存在着火时刻控制困难、燃烧不充分等问题,以天然气HCCI发动机为研究对象,通过建立HCCI单区模型,耦合CH4-O3反应机理,研究添加臭氧(O3)和一定臭氧浓度下初始参数对天然气HCCI发动机的燃烧过程和排放特性的影响。结果表明:添加O3可以使着火时刻提前,缸内温度和压力升高,且随着O3浓度增大效果越明显,增长幅度逐渐下降;提高进气温度使缸内压力峰值下降,当量比的增大使着火时刻延迟,提示可通过改变O3浓度和初始参数实现对燃烧相位的控制;O3浓度和发动机初始参数的增大均不同程度上促进了NOx排放。

Homogeneous compression combustion ignition（ HCCI） still has shortcomings such as difficulties of ignition timing control and insufficient combustion. Based on a certain natural gas HCCI engine,this article constructed a zero-dimension HCCI single-zone model,and coupled the chemical reaction mechanism of CH4-O3,to study the effect of adding different concentrations of ozone on the combustion process and emission characteristics of the natural gas HCCI engine. The results show that the addition of ozone in the intake air advances the ignition timing of the natural gas HCCI engine,and increase the temperature and pressure inside the cylinder. Increase ozone concentration will increase fore mentioned effects,with the increasing gradient decrease gradually. Higher intake air temperature decreases peak pressure and increasing equivalence ratio delays ignition. The combustion phrase can be controlled through modify ozone concentration and other parameters. Additionally,the addition of ozone and the variation of fore mentioned parameters both increase NOxemission in different degrees.