氧化时间对生物柴油性能及排放的影响

Effect of Biodiesel Oxidation Stability on Diesel Engine Performance and Emission

生物柴油在存储和运输过程中会发生氧化,使其密度、黏度以及氧化安定性指标发生不同程度的改变。应用傅里叶红外光谱等手段,分析不同氧化时间的生物柴油的微观表面官能团和黏度、密度等指标的变化规律;通过台架试验,进行186F柴油机燃烧生物柴油的性能、排放污染物的研究。结果表明,随着氧化时间的延长,生物柴油的黏度、密度等理化指标升高;同时,生物柴油组分中不饱和脂肪酸的C=C吸收峰峰值降低,饱和度增加,表面官能团—OOH吸收峰峰值增加,生物柴油中还原性物质增加,氧化安定性变差。氧化安定性差的生物柴油导致其排放的HC、烟度、颗粒数增加,NO_x有所降低;不同转速的负荷特性,有效燃油消耗率均有所增加。标定工况时,燃烧氧化720h和氧化2160h的生物柴油,有效燃油消耗率分别增加1.51%和3.45%。

Biodiesel will be oxidized during the process of storage and transportation.During the oxidation process,some parameters such as density,viscosity and oxidation stability of biodiesel will be changed.The tendency of biodiesel saturation along with the oxidation time was analyzed by Fourier infrared spectrum instrument.The engine performance and the emission of biodiesel under different oxidation time were tested by186 Fdiesel engine test bench,and the influence was also analyzed.The results showed that the density and viscosity increased with the increase of oxidation time.In addition,the component C=C absorption peak decreased and the surface functional groups—OOH absorption peak increased with the oxidation time increasing,leading to the oxidation ability of biodiesel downward.Oxidized biodiesel will cause the deterioration of combustion process.It will increase the emission of HC and smoke and decrease the NOxemission.The engine specific fuel consumption all increased under the load characteristic of various speed.In particular,under full load condition,the specific fuel consumption of the engine increased 1.51% and 3.45%respectively,when the biodiesel oxidized 720 hand 2160 hwere used.