Lubricity Improvement of the Ultra-low Sulfur Diesel Fuel with the Biodiesel

Ultra-low sulfur diesel fuel is essential requirement as per the emission regulation. With the adoption of hydrodesulfurization (HDS) process, the diesel fuel loses its inherent lubricity, however certain amount of lubricity of diesel fuel is needed to save several engine components from wear and failure. Though the loss of lubricity of the diesel fuel is observed with the removal of sulfur, it is mainly due to the loss of nitrogen and oxygen based polar trace compounds which are also removed in the HDS process. Unrefined biodiesels having little amount of monoglycerides (<0.8%) and free fatty acids also show better lubricity and fuel properties to be used as fuel lubricant. Biodiesel are also considered as the suitable blending compound with the diesel. This study found that the biodiesel blends up to 20% with the diesel fuel can effectively reduce both the wear of the tribo-contact surfaces as well as the friction coefficient. The use of biodegradable fuel lubricant has set away the threat of environment pollution by the diesel additives which are derived chemically. The oxidation stability and the low temperature properties of both the biodiesel and the vegetable oils can be improved with some chemical modification. It can be concluded that the use of biodiesel with the diesel fuel can be an appropriate option for effective engine lubrication system where only the fuel has to provide the required lubricity.