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Title: Optical studies of combustion of hydrous and anhydrous ethanol fuels in a spark-ignition engine
Author: Augoye, A. K.
ISNI:       0000 0004 8497 8056
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2016
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The azeotropic nature of hydrous ethanol at purity levels above 95.50 % significantly increases further purification cost, a factor which mitigates the use of ethanol in the global drive for CO2 reduction. Therefore, understanding the combustion mechanism of hydrous ethanol in comparison to anhydrous ethanol and traditional hydrocarbon fuels is required. This thesis focused on the combustion mechanism of hydrous and anhydrous ethanol (0-10% water volume) in comparison to iso-octane, gasoline and n-butanol fuels in a single-cylinder spark-ignition research engine operated at 1000 rpm with 0.5 bar intake plenum pressure. The engine was equipped with optical access and tests were conducted with both Port Fuel Injection (PFI) and Direct Injection (DI) mixture preparation methods with all tests conducted at stoichiometric conditions. Various optical diagnostics methods including High Speed Chemiluminescence imaging, Planar Laser Induced Fluorescence (PLIF) imaging and UV visible spectral acquisition were applied during this investigation. Peak in-cylinder pressure was observe to reduce as water content in hydrous ethanol was increased for both PFI and DI operation and peak in-cylinder pressures were higher for PFI operation compared to DI for all fuels tested. The effect of increasing water content in ethanol on combustion performance was more significant under DI operation due to less efficient mixing compared to PFI. Characterised high-speed chemiluminescence images showed similar trends to those obtained from heat release analysis. Characterisation of OH images acquired through Planar Laser Induced Fluorescence imaging of OH radicals revealed a linear sensitivity of measures of flame 'wrinkled-ness' to water content in ethanol within equivalent flame radius less than 6mm. The laminar burning velocity of hydrous ethanol was measured on a burner and it was found to reduce with increase in water content. Water volume fraction in ethanol was also observed to have some effect on measured regulated and unregulated engine exhaust emissions as well as mixture preparation strategy. Overall, PFI operation produced better engine combustion performance compared to DI under the engine test conditions implemented in this investigation due to better mixing efficiency. Also, statistically significant differences were recorded in engine combustion performance and flame characteristics between anhydrous ethanol and hydrous ethanol even when the latter had a water volume fraction of 5 %.
Supervisor: Aleiferis, P. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available