过量空气系数对氢内燃机冷起动燃烧及排放的影响

Combustion and Emissions Performance of a Hydrogen Engine During Cold Start at Different Excess Air Ratios

本文在一台1.6 L四缸进气道燃料喷射氢内燃机上,通过自主开发电子控制单元逐步调节氢气的喷射脉宽,试验研究了过量空气系数(λ)对氢内燃机冷起动燃烧与排放特性的影响。试验结果表明:当λ由1.54逐渐减小至0.72时,氢内燃机冷起动前6 s内,起动转速峰值逐渐升高,成功起动时间由2.4 s逐渐缩短至1.9 s,起动时间缩短了20.8%;相同循环数下,火焰发展期(θ(0-10))和快速燃烧持续期(θ(10-90))随λ的减小呈现逐渐缩短的变化趋势;NOx排放呈现先小幅上升,而后逐渐降低的变化规律,冷起动前6 s内NOx平均排放降低约84.4%,且在λ=1.41时NO_x排放峰值及平均排放均最高.此外,由于部分润滑油进入缸内参与燃烧而导致排放中会出现HC及CO污染物,且随λ的减小,HC及CO排放逐渐增加。

This paper experimentally investigated the combustion and emissions performance of a hydrogen engine during cold start at different excess air ratios(λ).The experimental results showed that,whenλdeclined from 1.54 to 0.72,the peak engine speed was increased while the successful starting duration for hydrogen engine was shortened from 2.4 s to 1.9 s,the successful starting duration was reduced by 20.8%.Both of the flame development and propagation periods were shortened with the decrease ofλ.In addition,NOx emissions increased slightly at first and then decreased gradually by decreasing A within the first 6 s.The average NOx emissions in the first 6 s reduced by 84.4%.it can be found that the highest peak NOx emission and the highest average NOx emission is found at the condition ofλ=1.41.Moreover,the emitted HC and CO emissions found in the exhaust manifold are increased with the decrease ofλdecreased due to the evaporated lubricant oil.