Lubrication Properties of Biodiesel: Experimental Investigation and Molecular Dynamics Simulations

In this work, biodiesels, such as such as ethyl stearate, ethyl oleate, ethyl linoleate, ethyl ricinoleate, were adopted as lubricity additives for low-sulfur diesel fuel, at the concentration range of 0.1 similar to 2 wt%. Tribological evaluation obtained from the High-Frequency Reciprocating Rig (HFRR) showed that double bonds or hydroxyl introduced in the carbon chain of the esters could lead to a higher lubrication performance. The lubricity efficiency order was explained by the molecular dynamics (MD) simulations. The lubricity enhancing properties of the esters are mainly determined by the cohesive energy of adsorbed films formed on iron surface. The greater the cohesive energy, the more efficiently it is that the esters enhance the lubricity of low-sulfur diesel fuel.