Ph.D. Tezi Görüntüleme | |||||||||||||||||||||
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| Summary: The conventional engine fuels are derived from crude oil based on limited natural sources. The fuel cost and total fuel consumption of the vehicle engines gradually increase. Furthermore, the demand for cleaner and more efficient engines requires to research the alternative fuels and to improve the fuel quality. In recent years, fumigation has become one of the most attractive methods for Diesel engines. Fumigation is a method by which alternative fuel is introduced into the engine by carbureting and vaporizing or injecting alternative fuel into the intake air stream. In the presented study, theoretical investigation of the effects of different gasoline and ethanol fumigation ratios on the engine performance and the exhaust emissions is aimed. For this purpose, a mathematical Diesel engine cycle model based on the First Law of Thermodynamics has been developed. This model includes a quasi-dimensional multi-zone combustion-modeling concept which consists of several sub-models such as spray formation, air-fuel mixing, swirl, heat transfer and emission models. The engine performance parameters and exhaust emissions for two different turbocharged Diesel engines having four and six cylinders fueled with pure Diesel fuel and Diesel fuel-gasoline/ethanol blends at different fumigation ratios have been predicted. Increasing gasoline fumigation at varied equivalence ratios increases the effective power, specific fuel consumption (SFC), carbon monoxide (CO) ratio while decrease effective efficiency and nitric oxide (NO) concentration. With increasing ratio of gasoline fumigation at constant equivalence ratios effective power, effective efficiency and CO ratio increase, however SFC and NO concentration decrease. Increasing ethanol fumigation at varied equivalence ratios increases the effective power, effective efficiency and CO ratio, however it decreases SFC and NO concentration. Effective efficiency, effective power and NO concentration increase generally by increasing the ethanol fumigation at constant equivalence ratios. In this case, SFC increases significantly and CO ratio exhibits generally increment tendency Key Words: Diesel Engine Cycles Modeling, Multi-Zone Combustion Modeling, Fumigation, Alternative Fuels, Spray Geometry, Dual Fueled Engines
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