满足国IV排放的DMCC发动机非常规排放研究

在一台电控单体泵增压中冷柴油机上采用柴油/甲醇组合燃烧方式(DMCC),后处理采用氧化催化转化器(DOC)耦合微粒氧化催化器(POC),对其排放特性开展了试验研究.结果表明:纯柴油模式时可挥发性有机物(VOCs)的排放体积分数在除怠速外的其它工况都小于5×10^-6,但甲醛在怠速工况时排放体积分数较高,为11.7×10^-6,苯系物的排放体积分数在各个工况下都小于6×10^-6;DMCC模式时,外特性时甲醇和甲醛排放均与柴油机相当,其它工况下甲醇和甲醛的排放体积分数大幅增加,都超过了250×10^-6,甲苯的排放体积分数要高于苯的排放体积分数;后处理器DOC+POC对甲醇和甲醛的催化效率均超过94%,对苯和甲苯的催化效率均超过75%.经过后处理器之后的柴油甲醇双燃料发动机的非常规排放物的比排放量为0.125 g·kW^-1·h^-1,原机的比排放量为0.209 g·kW^-1·h^-1,DMCC模式的非常规排放物要优于原机.

Unregulated emissions from DMCC engines of national IV emission standard

In the present work, the effects of diesel-methanol compound combustion (DMCC) and diesel oxidation catalyst coupled with a particulate oxidation catalyst (DOC+POC) on unregulated emissions was studied. A 4-cylinder, turbo-charged, electronic unit pump diesel engine equipped with a methanol injection system was used in the experiment. The results showed that the unregulated volatile organic compounds (VOCs) emissions were extremely low at diesel mode at all conditions except for idle condition, while benzene, toluene, ethylbenzene, and xylenes (BTEX) emissions were below 6×10^-6 at all conditions. At idle condition, only formaldehyde had high emissions of 11.7×10^-6. At DMCC mode, methanol and formaldehyde emissions increased significantly over 250×10^-6. However, the introduction of methanol at full load does limit methanol and formaldehyde emissions. In contrast to diesel mode, the concentration of toluene is higher than benzene when the engine operates at DMCC mode. The catalyst conversion efficiency of DOC+POC on methanol and formaldehyde is higher than 94%, while the conversion efficiency for benzene and toluene is more than 75%. The unregulated emissions of DMCC coupled with DOC+POC is much better than diesel mode, with the averaged unregulated emissions of 0.125 g·kW^-1·h^-1 and 0.209 g·kW^-1·h^-1, respectively.