Lubricity Properties of Palm Oil Biodiesel Blends with Petroleum Diesel and Hydrogenated Vegetable Oil

While the methyl ester structure in biodiesel is responsible for lubrication improvement in base fuels with poor lubricity properties such as ultra-low sulfur diesel and non-upgraded HVO, relatively little is known about its effect on all-level blends, which would provide higher energy security for biodiesel utilization. In this study, binary blends of palm oil biodiesel (POB) with commercial petroleum diesel fuel (DF) and HVO at every 10%-v/v blend point were analyzed using a high-frequency reciprocating rig (HFRR) according to the standard method of ASTM D6079. It was found that the addition of POB successfully improved the lubricating properties of DF-CN48 and DF-CN51 and efficiently acted as a lubricity improver that showed a minimum friction coefficient and improved the specific wear rate. The adsorption of ester molecules on the metallic surfaces acted as a protective layer during the rubbing process, resulting in lubricity improvement for the diesel fuel. Interestingly, the 60–90%-v/v POB blend with HVO showed a lubricity capacity that competed determinatively and attractively, resulting in a non-ideal contribution to the changes in the friction coefficient, WSD formation, and specific wear rate.