Improving dual fuel system to provide use of variable octane numbers gasoline in SI engines

ABSTRACTThe fuel octane required for knock-free operation of a spark-ignition engine varies widelywith load. Therefore, the octane rating of the fuel used is under-utilized, except near fullloading operating conditions. Such reduction in octane requirements implies reductions in thecost and energy expenditure of producing gasoline, as well as reductions in the use of octaneenhancers which produce particularly undesirable emissions such as tetraethyl lead andaromatic hydrocarbons. The cost and energy expenditure of producing gasoline increases withoctane rating. This observation led us to the idea of a dual-fuel system to provide anadjustable mixture of two fuels of different octane ratings that would match the instantaneousrequirements of the engine. A dual-fuel system would be particularly attractive for citydriving characterized by how engine power demand allowing substantial use of low octanefuel.In this study, a dual-fuel system was developed in spark-ignition engine. It can provide theoctane rating which engine requires for knock free operation in urban traffic and enables touse two fuels having different octane ratings. It is investigated the advantages of developedsystem compared to conventional system.As a result, it is observed that dual fuel system keeps high octane fuel consumption minimumby blending high and low octane fuels to provide octane rating which engine requires.Because of decreasing high octane fuel consumption, octane improving cost decreases.Therefore, it will be significantly for national economy.Usage of this kind of system doesn?t effect the engine performance. In addition, it providessignificant reduction of exhaust emissions. Owing to flexibility of the system, after makingsmall changes in software, alternative fuels can be used easily.Keywords: knock, octane rating, engine management, fuel system,x