柴油-生物柴油-乙醇混合燃料发动机的醛类化合物排放特性研究

Study on Aldehydes Emission of BE-D Blend Fuel Engine

在一台单缸柴油机上进行燃用BE-D与柴油后的醛类排放物试验对比,采用衍生法捕集发动机排气中的醛类污染物,应用液相色谱分析醛类成分与浓度。结果表明,排气中总醛类化合物的排放率随发动机负荷增加而减少;甲醛和乙醛是排放的醛类中占有率最大的两种醛,大部分工况下占有率达80%左右;C4以上的醛占有率很低。随发动机负荷增加,甲醛占有率增加,乙醛占有率减少;大多数工况下甲醛占有率比乙醛高。BE-D的总醛类化合物的排放率在1200r/min和1800r/min下较柴油低,1500r/min下较柴油高。BE-D的丙醛排放比柴油高,丙烯醛排放却比柴油低;丁醛排放在高负荷下BE-D比柴油高,低负荷下则比柴油低。提出了醛类化合物毒性当量的计算方法,并进行了计算,发现BE-D的醛类化合物毒性当量明显比柴油低,最低达40%。

Comparable experiments on emission characteristics for BE-D and diesel were conducted on a single cylinder diesel engine.Exhaust aldehydes emissions were sampled with derivation method,and the components and concentration were analyzed by liquid chromatography.The results show that total aldehydes emissions rate decrease with the increase of load.Formaldehyde and acetaldehyde are the highest contents in all aldehydes emissions,about 80% under most conditions.The occupancy ratios of aldehydes with more than four C atoms are low.With the increase of load,occupancy ratio of formaldehyde increases while that of acetaldehyde decreases.Under most conditions,occupancy ratio of formaldehyde is higher than that of acetaldehyde.The total aldehydes emission rate for BE-D is lower than that of diesel at 1 200 r/min and 1 800 r/min,but is higher at 1 500 r/min.Propionaldehyde emission for BE-D is higher than that of diesel,while acrolein emission is lower than that of diesel.Butyraldehyde emission for BE-D is higher than that of diesel under medium and heavy load,but is lower than that of diesel under low load.This paper also presented a calculation method for toxic equivalence of aldehydes emissions,and the results show that toxic equivalence of aldehydes emissions for BE-D is much lower than that of diesel,up to a maximum of 40%.