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Title: The impact of biofuel ethanol on lubrication and friction in the piston assembly of a gasoline engine
Author: De Silva, Prashan Roger
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2012
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The objective of the research presented in this thesis was to investigate and quantify the impact of biofuel ethanol and the associated water contamination into a commercially available automotive gasoline engine lubricant on the frictional response of piston ring/cylinder liner contacts and the resulting implications for fuel economy under problematic cold-start/warm-up/short-journey driving conditions. Whilst road transport is a major driver of global economic growth, it is also a primary user of fossil fuel based energy and a major emitter of Carbon Dioxide (C02). Therefore, increasingly stringent legislation demanding the use of biofuels in conjunction with conventional fossil fuels has been put in place. Even though biofuels are being blended into conventional gasoline and diesel at varying concentrations, information relating to the impact of these fuels on automotive engine lubrication, friction and fuel economy is scarce. A comprehensive and rigorous laboratory bench-top screening test programme using a reciprocating tribometer and Statistical Experimental Design was developed for the first stage of this investigation. Bespoke engine test programmes were also conducted to identify areas susceptible to ethanol and water dilution on the piston assembly and cylinder liner and to quantify fuel and water dilution into the lubricant present along the cylinder liner wall and in the sump. Tribometer investigations showed that significant reductions in friction resulted when the piston ring/cylinder liner contacts were lubricated with the lubricant-ethanol-water mixtures and the separated phases of these mixtures compared to the formulated lubricant. Temperature measurements on a single cylinder gasoline engine highlighted that lubricant present on the piston skirt, the connecting rod and on the intake side of the cylinder liner was highly susceptible to ethanol and water contamination under cold-start/warm-up conditions. Fuel dilution measurements on the same engine revealed that lubricant present on the upper cylinder liner, at top dead centre, was highly contaminated with ethanol, gasoline and water compared to that present lower down the cylinder, mid-stroke and bottom dead centre, and in the sump. again under cold-start/warm-up conditions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available