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Title: Alcohol fuel effects on mixture preparation and combustion in SI engines
Author: Malcolm, J. S.
ISNI:       0000 0004 8502 8677
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2015
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The automotive industry is constantly trying to reduce exhaust emissions and to introduce alternatives to fossil fuels. Pressure from increasingly environmentally aware consumers and UK/EU emissions targets, mean that understanding the physics of the behaviour of various alternative fuels in the internal combustion engine is of huge importance to the automotive industry. One suggested alternative is to use alcohols as fuels. At present in Europe there is some crop based ethanol added to unleaded fuel, but as further legislation is considered the percentage of alcohols may to increase. At present even the well-established consumers of alcohol fuels such as Brazil run their vehicles using port fuel injection (PFI) systems and as direct injection spark ignition (DISI) becomes more popular within the automotive industry, for reasons of reported increases in efficiency and greater possibilities in combustion control due to injection strategies, the question of how this type of injection system can be best matched with the alcohol fuels is still not fully answered. This research aims to increase understanding of the physics involved in the ingestion and combustion of alcohol fuels in modern engine geometries. The use of an optical research engine allows images of DI spray formation, as well as PFI and DI combustion, to be captured and analysed by image processing techniques. In particular, the injection process of blends of alcohols with fossil fuels from a DI pressure-swirl injector is examined to determine the thermo-fluid dynamics and flow interactions affecting the spray development. The use of laser-based optical techniques further allows quantification of the in-cylinder air flow and fuel mixing processes to achieve an insight into how differing alcohol fuels effect DI in-cylinder air flow characteristics. Specifically in-cylinder PIV is undertaken to examine flow evolution both with and without alcohol fuels. Fuel effects are also discussed with regard to future optimization of engines to operate on these alternatives. Comparisons are made between different blends of alcohols and fossil fuels in terms of combustion images and incylinder rates of heat release. These are undertaken both visually in the optical engine, and thermodynamically in a thermodynamic engine of the same geometry, allowing greater insight into real-world combustion and exhaust emissions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available