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Title: Combustion characteristics of a compression ignition engine running on biodiesel and gasoline blended fuels
Author: Kevric, Arman
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2013
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An experimental investigation of the effects of fuel composition on the ignition delay and heat release characteristics of a light duty, automotive compression ignition engine has been carried out. The ignition delay is defined as the period between the start of the main fuel injection event and the start of combustion (SOC). The research has covered a range of fuel types and blends to maximise the effects of composition on the ignition delay and heat release. The fuels used were diesel, gasoline and FAME (Fatty Acid Methyl Esters) produced from rapeseed oil, coconut oil and waste cooking oil. All the engine test studies were carried out using a 2.4 litre displacement, direct injection Ford Puma engine, at test conditions representing low load, mid load and high load at 2000rpm, with EGR rates of up to 35%. Single equation, semi-empirical ignition delay models based upon the Arrhenius equation were studied and developed to fit the experimental ignition delay data, and thus incorporate fuel composition effects. Fuel composition is shown to affect the duration of the ignition delay, but after the start of combustion the heat release characteristics, for a given energy supplied in fuel, proved to be relatively insensitive to fuel composition effects. The premixed fraction is shown to be directly proportional to the ignition delay. The ignition delay of biodiesel fuel is up to 15% shorter than diesel while a gasoline blend of 50% gasoline/50% diesel lengthens the ignition delay by up to 30% with respect to diesel. These differences in the ignition delay affect the engine thermal efficiency by up to 2% due to combustion phasing effects. Gasoline fuel blended up to 80% (by volume) with diesel was combusted successfully, resembling PCCI (Premixed Charged Compression Ignition) combustion regimes, while biodiesel fuel types RME (Rapeseed Methyl Esters), CME (Coconut Methyl Esters) and WCO (Waste Cooking Oil Methyl Esters) all showed differences in heat release characteristics due to ignition delay differences. Calibration changes are necessary to compensate for the fuel composition effects on the ignition delay and subsequent combustion characteristics. An engine specific, single equation ignition delay model was developed that successfully described the experimental ignition delay data over the fuel range of fuel composition: rID = 4.32p-l.02/'P-O.2exp (:;) where EA = A.Kevric University of Nottingham , ' )t8186 . Based upon the analysis of combustion characteristics of the experimental CN+ZS) data, the initial form of a universal ignition delay model was developed, composing of a physical delay portion and a chemical delay portion. A.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available