Knock Properties of Oxygenated Blends in Strongly Charged and Variable Compression Ratio Engines
Replacing the conventional fossil fuel totally or partially with alcohols or ethers in spark-ignition (SI) engine is a promising way to reduce pollutant emissions. A large number of studies on alcohol-containing blends in SI engines could be found in the literature. Nonetheless, investigations of ether-containing blends are by far much less numerous, especially for modern boosted engines. Blending with ether compounds might change the burning rate at high pressure, which consequently changes the anti-knock properties of these fuels and leads to a deterioration in the vehicle drivability. This work reports experiments carried out in two one-cylinder engines: one is a naturally aspirated, variable compression ratio engine, and the other is a strongly charged optical engine. Three fuels with different RON and MON numbers were tested: Iso-octane, a blend Ethyl Tert Butyl Ether (ETBE) with a primary reference fuel, and a commercial gasoline fuel containing 5% by volume of ethanol (E05).