Tribometer investigation of the frictional response of piston rings with lubricant contaminated with the gasoline engine biofuel ethanol and water

Abstract

Ethanol is considered a potential long-term replacement for gasoline but information on the impact of ethanol on engine lubricant performance is scarce. Therefore, it is of prime importance to investigate the effect of ethanol on lubricants and engines that currently operate on gasoline. A bench-top test programme was undertaken on a modified Plint TE77 reciprocating tribometer to simulate the piston ring and cylinder wall interface. The Taguchi statistical experimental design method was used to quantify the effect of ethanol and the associated water contamination on friction with a commercially available fully formulated lubricant. Control factors and potential interactions were selected based on the TE77 capability and typical gasoline engine operating conditions. The statistical results show that while independently ethanol does not significantly contribute to friction reduction, the independent contribution from water is moderate when compared with the combined effect of ethanol and water. The water-temperature and load-speed interactions provide a small contribution to friction reduction while the ethanol-load and temperature-load interactions contribute moderately to the same.

Tribometer Investigation of the Frictional Response of Piston Rings when Lubricated with the Separated Phases of Lubricant Contaminated with the Gasoline Engine Biofuel Ethanol and Water

“…Distilled water was used in order to eliminate the impact of minerals such as calcium present in normal water on the experimental results. These materials are consistent with the first stage of this research [18].…”

“…The material of the cylinder liner sections was grey cast iron whilst the piston rings sections were cut from cast iron-chromium coated top compression rings. The details and specifications of the ring and liner sections are provided in De Silva et al [18].…”

“…Concentrations of ethanol and water were selected based on the research and field test data reported in the literature [18]. The separated oil phase experiments were conducted at liner temperatures of 70 and 110°C to evaluate the performance of the surface active additives which are designed to operate in this temperature regime.…”

“…A previous paper by the authors [18] reported an investigation to quantify the effect of ethanol and water on the frictional response of a top piston ring when lubricated with a fully formulated gasoline engine lubricant contaminated with ethanol and water. In this paper, the next stage of this research is described where the frictional response of a top piston ring lubricated with the separated phases the same contaminated lubricant forms when left undisturbed, as would happen when a vehicle is parked or garaged, was studied.…”

Effects of Ethanol Contamination on Friction and Elastohydrodynamic Film Thickness of Engine Oils

“…Since this ethanol accumulation is expected to influence lubrication and therefore friction, De Silva et al used a Plint TE77 reciprocating tribometer to investigate friction at the piston ring/cylinder wall interface for a fully formulated gasoline engine lubricant contaminated with ethanol and water (De Silva, et al (15)). They found that although the presence of ethanol did not affect friction measurements significantly, the combined presence of water and ethanol in the lubricant reduced friction.…”