不同点火提前角时HCNG发动机的燃烧与排放特性

Combustion and Emission Characteristics of a HCNG Engine under Various Spark Timings

在一台火花点火天然气发动机上开展了在不同点火提前角下燃用不同体积掺氢比（0%～50％）的天然气掺氢燃料（HCNG）的试验研究，进行热效率、燃烧放热率、循环变动及排放特性的分析。结果表明：与原天然气发动机相比，HCNG发动机的最大扭矩点火提前角（MBT）减小，MBT时指示热效率变化不大；点火提前角增大时，火焰发展期增长，最大压力变动率减小，快速燃烧期和平均指示压力变动率先减小后增大；在相同点火提前角时，以上4个参数均随掺氢比的增加而减小。NOx、CO排放浓度随掺氢比增加而增大，CH4排放则相反。

An experimental study was conducted on a HCNG spark ignition engine to examine the effects of hydrogen blending ratio （0 %-50 %） and spark timings on the thermal efficiency, heat release rate, cyclic variations and exhaust emissions of the engine. The results show that hydrogen addition can decrease the spark advanced angle for best torque （MBT） but has no Obvious effects on engine thermal efficiency when operating at MBT. As the spark advanced angle increases, flame development duration increases while coefficient of variation（CoV） in peak pressure decreases, rapid burn duration and in indicated mean effective pressure（imep） decreases at beginning and then increases. At fixed spark timing, the above four parameters can simultaneously be improved by adding hydrogen. NOx and CO emissions increase while CH, emission decreases with the increase of hydrogen blending ratio.