采用2,4-二硝基苯肼(DNPH)衍生法和高效液相色谱(HPLC)技术,对柴油机排气中的醛、酮污染物进行了捕集和分离测定,考察了柴油机燃用BD100、BD50、BD0时,不同负荷下的醛、酮污染物排放规律,分析了燃料组分、缸内温度、压力、排气温度等对醛、酮污染物排放的影响。研究结果表明,该方法可实现微量醛、酮污染物的准确、快速测定;柴油机排气中含量较高的羰基物有甲醛、丙醛、丙烯醛、乙醛、丙酮、丁酮和丁醛,其排放水平均随负荷增大而呈下降的趋势;高负荷时,高温区域的滞留时间延长,醛、酮类被再次氧化、转化几率增加;较高的排气温度会促使排气中的醛、酮类物质和HC燃料再次氧化生成CO和CO2。
Carbonyl emissions from a diesel engine were sampled,captured and measured by using method of 2,4-dinitrophenyl hydrazine(DNPH)and high performance liquid chromatography(HPLC).Emission characteristics of carbonyl at different loads were investigated.The influencing factors to both aldehyde and alkone emissions,like composition of fatty acid,in-cylinder temperature and pressure,and exhaust temperature were analyzed.Result show that this method is good for the simultaneous determination of aldehyde and ketone emissions.As load is increased,the carbonyl emissions of aldehyde and alkone are decreased.Probability of re-oxidation and transformation in carbonyl is increased at high loads.The residence duration at high temperature is increased,and high exhaust temperature leads to re-oxidation of carbonyl and HC into CO and CO2.