混氢汽油机的燃烧及排放特性试验

针对汽油机热效率低、排放高的问题,通过进气混氢降低汽油机的能耗和排放.在一台4缸汽油机上安装一套电控多点顺序气道氢气喷射系统,可实现汽油和氢气在进气道的现场混合.在发动机转速为1 500 r/min及理论当量比条件下,选择混氢体积分数为1%、1.5%、2%、3%的4种不同进气,对混氢汽油机的燃烧与排放特性进行了试验研究.试验结果表明:在混氢体积分数为3%的工况下,与原机相比,发动机制动热效率平均提高了3.23%,缸压峰值的循环变动平均减少了3.18%.随着进气中氢气体积分数的增加,发动机着火滞燃期和燃烧持续期缩短,燃烧峰值压力增加,CO_2与HC排放明显降低,但NO_x与CO排放有所增加.混氢对改善发动机性能效果显著.

Experiment on Combustion and Emissions Characteristics of an IC Engine Blended With Hydrogen

In the view of low thermal efficiency and high emissions of spark ignition (SI) engines,this paper investigated the effect of hydrogen blending at intake ports to an SI engine on improving its economic and emissions performance.The experiment was carried out on a modified 4-cylinder SI engine on which hydrogen could be injected into the intake ports sequentially via an ECU (Electronic control unit) based control system and mixed with gasoline on-line.The combustion and emissions characteristics of a hydrogen-blended IC engine were investigated under the conditions of 1 500 r/min and the stoichiometric equivalence ratio with four different hydrogen volumetric fractions of 1%,1.5%,2%,3%.The test results demonstrated that, compared with the original engine,the brake engine thermal efficiency was increased by 3.23 % and the cycle- by-cycle variations of the peak in-cylinder pressure was reduced by 3.18 % on average at the hydrogen addition fraction of 3 %.Ignition delay and the rapid burning duration were shortened;the peak in-cylinder pressure was increased;CO_2 and HC emissions were obviously lower with the increasing fraction of hydrogen in the intake.However,NOx and CO emissions were also increased.In a word,the addition of hydrogen to a gasoline-fuelled IC engine is a good way to improve engine performance.