The Effect of Biofuel on the Corrosion and Wear of Automotive Engine Components

Soot particles produced during diesel engine combustion process are of strong interest within the fields of environmental science (global warming, air pollution), air filtration and combustion science (the optimization of the combustion process). Diesel fuel production from renewable resources such as vegetable oils and animal fats offer the potential to reduce fossil carbon emissions and produce alternative ultra-clean fuels for transport and industrial use. It is well known that biodiesel, neat or in blends, can provide reduced particulate matter (PM) mass emissions through either oxygen content or enhanced air due to the higher boiling range of biodiesel. Recent observations have shown an oxidation reactivity variation with soot derived from different fuels. However, the manner in which crystallinity or nanostructure affects soot oxidation rates has not been clarified for diesel fuel soot, whether it is derived from conventional or alternative (e.g. renewable) fuel sources. This study has looked at the comparison of soot nanostructures of particulates produced from three different fuels (an ultra-low sulphur diesel fuel, its B20 blend and pure biodiesel B100) with a diesel engine by means of high resolution transmission electron microscopy (TEM) imaging. TEM studies of soot samples collected on a soot catcher under conditions relevant to different biodiesel blends, revealed a nanostructure that to our knowledge, has not been previously reported for diesel soot particulates. The immersion corrosion tests of biodiesel B100 were conducted at six different temperatures; 25°C, 80°C, 90°C, 100°C, 110°C and 120°C, each for 270 hours. Each sample was weighed at the commencement of the tests and again at the end. Any difference in those weights was used to inform on the corrosion characteristics of the particular fuel on each metal type. Under the experimental conditions, copper and brass were more susceptible to corrosion in biodiesel than aluminium and steel.