Experimental Study On The Combustion Characteristics Of A Spark Ignition Engine Fuelled With Alcohol-gasoline Blends

Energy saving and environmental protection are currently two major issues confronted with when developing internal combustion engines. Finding clean alternative fuels is one solution to solve the problems above. Alcohol, as one of renewable eco-friendly fuels, can partially replace gasoline, decrease petroleum consumption and exhaust emissions from automotive vehicles. Therefore, the study on the application of alcohol fuels has theoretical significance and practical values.Through improving a self-developed engine control system software for a spark ignition engine by creating additional functions controlling the injection number and duration at the cold start of engine, the maximum engine speed and independently starting/stopping injection and ignition of each cylinder, a convenient electronic control platform was established. On the other hand, the combustion characteristics and fuel consumption were investigated when ethanol-gasoline blends and bio-butanol-gasoline blends were used. The results show that:At low and medium loads, the ignition timing for maximum brake torque (MBT) avdances with the increase of ethanol content in the ethanol-gasoline blends, but the MBT of bio-butanol-gasoline blends delays. At high load, the MBT of different alcohol-gasoline blends is very close. Different alcohol-gasoline blends have different impact on the indicated thermal efficiency of the engine. The indicated thermal efficiency of ethanol-gasoline blends increases with ethanol content in the blends, while the indicated thermal efficiency of bio-butanol-gasoline blends increases and then decreases with the increase of bio-butanol content. The ethanol-gasoline fuels have shorter combustion duration and better anti-knock characteristic than gasoline and bio-butanol-gasoline blends. The specific fuel consumption of the bio-butanol-gasoline blends is higher than that of gasoline but is lower than that of ethanol-gasoline blends. The energy consumption of alcohol-gasoline blends is relative lower compared to gasoline fuel. At high loads, different alcohol-gasoline blends have slight effect on the cycle- by-cycle variations in indicated mean effective pressure. In addition, the volumetric efficiency of the engine is almost unchanged when using different fuels.