火花点火天然气掺氢发动机稀燃极限的影响因素

Influence Factors of the Lean Operation Limit for a Spark Ignition Hydrogen Enriched Natural Gas Engine

通过试验分析了在天然气中掺入氢气对拓展天然气发动机稀燃极限的作用,并分析了发动机的各种运转参数对燃用不同体积掺氢比的天然气/氢气混合燃料(H2-CNG)稀燃极限的影响。试验结果证明:氢气的掺入可大幅拓展稀燃极限;负荷增大、进气温度升高都有利于提高稀燃极限;在小负荷时,转速提高导致天然气稀燃极限增大,大负荷时情况则相反,而天然气、氢气混合燃料稀燃极限对转速则不敏感。并且针对一种掺氢比和一定的工况,存在一个最佳的点火提前角使得稀燃极限最大。

In order to extend the lean operation limit （LOL） of a spark ignition natural gas engine to further decrease its NOx emission, an experimental research was conducted to investigate the effect of hydrogen addition and various engine operating parameters on the LOL. The results show that hydrogen addition can significantly extend LOL and both the increase of engine load and intake air temperature result in greater （leaner） LOL. The effect of engine speed on LOL is not so straightforward. When fueled by pure CNG, LOL becomes greater with the increase of engine speed at low load, but while at high load, LOL drops if engine speed increases. However, when fuelled by hydrogen enrichment compressed natural gas （HCNG）, engine speed has no obvious effect on LOL. Also an optimum spark advance to maximize LOL exists for a specific engine operating condition.