Comprehensive analysis of properties of green diesel enhanced by fatty acid methyl esters

Abstract

This study systematically investigates the lubricating properties of bio-hydrogenated diesel (BHD), a synthetic diesel produced through biomass hydrogenation of vegetable oil. Despite having similar chemical properties to petroleum diesel, BHD has poor lubricating properties due to the removal of sulfur and oxygenated compounds during the hydrogenation process, which could damage the engine. To address this issue, fatty acid methyl esters (FAME) was added as an additive to BHD to enhance its fuel and lubricating properties. FAME is a polar molecule with good lubricating properties that adsorb on the surface to protect against wear. The study found that adding as little as 5% FAME significantly improved the lubricating properties of BHD. The wear scar diameter (WSD) decreased from 609 μm to 249 μm, and the average film was 94% with an average coefficient of friction of 0.138 by only 5% FAME addition investigated by High Frequency Reciprocating Rig with ISO 12156-1: 2018. This shows that blending FAME with BHD could reduce engine wear and improve its lubricating properties. Disc samples were analyzed using a Scanning Electron Microscope (SEM), OLS5100 3D laser microscopy, and Fourier Transform Infrared Microscopy (FTIR) to examine the worn surface both physically and chemically. An increase in the percentage of FAME addition to BHD resulted in a smoother worn surface, exhibiting reduced delamination and debris compared to pure BHD. This effect was attributed to the protective film formed by FAME. The study highlights the potential of FAME as an additive to enhance the lubricating properties of BHD and reduce engine wear.