点燃式缸内直喷甲醇发动机甲醛和未燃甲醇排放特性

Formaldehyde and unburned methanol emissions from a spark-ignition direct-injection methanol engine

基于气相色谱和液相色谱相结合的甲醛和甲醇测量方法,试验研究了点燃式缸内直喷甲醇发动机甲醇喷射正时、点火正时和过量空气系数在均质燃烧模式下对甲醛和未燃甲醇排放的影响。试验结果表明,甲醇喷射正时、点火正时和过量空气系数对该发动机甲醛和未燃甲醇排放有显著影响,并且甲醛和未燃甲醇排放随喷射正时、点火正时和过量空气系数的变化呈相反的变化趋势。推迟喷射甲醇、提前点火及采用稀混合气可以降低甲醛排放。

The effects of methanol injection timing, ignition timing and excess air ratio on formaldehyde and unburned methanol emissions from a spark-ignition direct-injection methanol engine under homogenous combustion mode were investigated experimentally by means of a measurement method in which the gas chromatography and the liquid chromatography were used to separate and measure formaldehyde and methanol. The results show that the methanol injection timing, ignition timing and excess air ratio affect significantly the formaldehyde and unburned methanol emissions from a spark- ignition directqnjection methanol engine. The variations in emitted formaldehyde and unburned methanol show opposite tendencies with the variations in the methanol injection timing, ignition timing and excess air ratio. Retarding methanol injection timing, advancing ignition timing and using lean mixture decrease formaldehyde emission.