掺氢比对氢-甲醇发动机稀薄燃烧及排放影响

为探究掺氢比对氢-甲醇发动机稀薄燃烧性能的影响，在一台1.8 L涡轮增压缸内直喷汽油机 （GDI） 改装的氢-甲醇发动机上，开展了不同燃空当量比和不同掺氢比条件下的甲醇发动机掺氢燃烧和排放试验研究。结果表明，在稀燃条件下，增大掺氢比能提高发动机缸内最高燃烧压力及放热率峰值，且燃烧相位提前，燃烧持续期缩短。在稀燃情况下适当掺氢有助于改善循环变动，混合气越稀改善效果越好，但随燃空比和掺氢量增大时，循环变动却有恶化的趋势。当燃空当量比大于 0.71 时，增大掺氢比能改善 HC 排放；当燃空当量比大于 0.83 时，掺氢能改善 NOx排放，但 CO 排放恶化；当燃空当量比小于0.83时，增大掺氢比导致NOx排放恶化但CO排放降低。

Effect of H2 Ratio on Combustion and Emissions of a H2/Methanol Engine During Lean Burn Operation

In order to study the influence of hydrogen mixing ratio on the lean combustion performance of hydrogen-methanol engines, experiments were carried out on a hydrogen-methanol engine modified by a 1.8L turbocharged gasoline direct injection (GDI) engine, considering different fuel-air equivalence ratios and hydrogen mixing ratios. The hydrogen-mixed combustion and emissions of the methanol engine were focused. The test results show that under lean-burn conditions, as the hydrogen ratio increases, the maximum combustion pressure and the peak heat release rate in the engine cylinder increase, the combustion phase is advanced and the combustion duration is shortened. The leaner combustion condition with the proper amount of hydrogen improves even more the cycle fluctuation. However, when the fuel-air ratio and the amount of hydrogen increase, the cycle fluctuation tends to deteriorate. For the fuel-air equivalence ratio greater than 0.71, increasing the hydrogen mixing ratio can improve HC emissions. For the fuel-air equivalence ratio greater than 0.83, hydrogen admixture improves NOx emissions; however, increasing the hydrogen mixing ratio deteriorates CO emissions. For the ratio less than 0.83, increasing the hydrogen mixing ratio leads to the deterioration of NOx emissions and the decrease of CO emissions.