棉籽油生物柴油和柴油混合燃料的润滑特性

为研究生物柴油的润滑特性，该研究用棉籽油与甲醇和乙醇分别进行酯交换反应，制备出甲酯生物柴油和乙酯生物柴油。然后将它们分别以不同体积比率与市售0#柴油混合，制备出不同比率的生物柴油/柴油混合物。通过四球摩擦磨损试验机考察了这些混合物的润滑特性。结果表明：不同碳醇与棉籽油制备的生物柴油对柴油的润滑性能均具有增效作用，且随着生物柴油添加量的增加，柴油的润滑性能得到提高；但市售0#柴油对不同碳醇制备的生物柴油感受性不同，分别添加20%的甲酯生物柴油和乙酯生物柴油到0#柴油时，发现混合柴油的最大无卡咬负荷（PB值）分别提升了94.1%和29.4%；同时，甲酯生物柴油对柴油的最大无卡咬负荷影响大，而乙酯生物柴油/柴油的减摩性和抗磨性都好于甲酯生物柴油/柴油；游离脂肪酸对生物柴油润滑性也有较大影响。该研究为生物柴油的应用打下基础。

Lubrication characteristics of mixed fuel between cottonseed oil biodiesel and diesel

Biodiesels were synthesized by the transesterification reaction of cottonseed oil and methyl alcohol and ethyl alcohol, respectively, in order to study the lubricating properties of biodiesel. The biodiesel/diesel mixtures were then obtained by mixing the prepared biodiesels and commercial diesel. The lubrication properties of the obtained mixtures were studied on a four-ball tribological tester. The results showed that the synthesized biodiesels could improve the lubrication properties of diesel obviously. The increase of the biodiesel had a positive effect on the lubrication properties of the mixtures. Moreover, the lubrication properties could be affected remarkably by the different alcohols. The extreme pressure (PB value) of the mixture was increased by 94.1% and 29.4% by adding 20.0 vol% methyl ester biodiesel and ethyl ester biodiesel, respectively. The biodiesel from ethyl alcohol could improve the lubrication properties more than that from methyl alcohol. Free fatty acids can also affect the lubricity of biodiesel. The study lays the foundation of application of biodiesel.