在一台加装独立的甲醇供给系统的自然吸气柴油机上,采用柴油甲醇组合燃烧模式(DMCC)进行台架试验.利用气相色谱仪分析技术,全面研究并总结了甲醛在不同的发动机工况如转速、负荷、排气温度(改变柴油氧化催化转化器DOC位置)和不同甲醇替代率的情况下的排放规律以及甲醛和未燃碳氢(HC)之间的相互关系.研究结果显示,DMCC模式下的甲醛排放主要受到负荷、甲醇替代率、排气温度3方面的共同影响.在中等负荷排温在240～380℃之间时,DOC促进甲醛的生成;在高负荷排温在400℃以上时,DOC减少甲醛排放.在同样工况下将DOC位置移近排气歧管对减少甲醛排放有显著的作用.在此情况下,当排气温度超过400℃,DOC后的甲醛排放体积分数降低到(10～15)×10-6左右,与燃用纯柴油的甲醛浓度相近.另外,未燃碳氢和甲醛的转化效率的规律有一定的关联.当排温高于320℃以后,尽管HC迅速下降到比原机还低的水平,但甲醛排放浓度却比较高.当排气温度超过380℃并将DOC位置移近排气歧管,此时,HC与甲醛的排放将同步减少直至接近零排放水平. In a naturally aspirated diesel engine with a separate methanol supply system, the diesel-methanol combined combustion mode (DMCC) was used to carry out the bench test.Using gas chromatography analysis technology, a comprehensive study and summary of formaldehyde in different engine operating conditions Such as the rotation speed, the load, the exhaust temperature (to change the DOC position of the diesel oxidation catalytic converter) and different methanol replacement rate and the correlation between formaldehyde and unburned hydrocarbon (HC) .The results show that DMCC The formaldehyde emission in the mode is mainly affected by the load, the methanol substitution rate and the exhaust temperature 3. When the medium load is between 240 and 380 ℃, the DOC promotes the formation of formaldehyde. When the high load exhaust temperature is 400 ℃ , The DOC reduces the formaldehyde emission and moving the DOC near the exhaust manifold in the same condition has a significant effect on reducing the formaldehyde emission.In this case, when the exhaust temperature exceeds 400 ° C., the formaldehyde emission volume after the DOC (10 ~ 15) × 10-6, which is similar to the formaldehyde concentration of pure diesel fuel.In addition, there is a certain correlation between the unburned hydrocarbon and formaldehyde conversion efficiency.When the temperature is higher than 320 ℃ Although HC fast The rate of formaldehyde emission is relatively high.When the temperature of the exhaust gas exceeds 380 ° C and the position of the DOC is moved close to the exhaust manifold, the emission of HC and formaldehyde will decrease synchronously until it approaches Zero emission level.