High-Concentration Ethanol Fuels for Cold Driving Conditions

摘要

VTT has together with the Finnish energy company St1 tested different high-volume ethanol fuel (E85) samples in order to find the optimum composition for this fuel to perform satisfactorily in low ambient temperature driving conditions encountered in Finland quite frequently during the winter season. Altogether seven different fuel compositions were evaluated, with 70-85 % of anhydrous bioethanol, and various different mixes of regular petrol components and some specific species like ETBE, butane, iso-butanol etc. As a reference, new Euro-quality 95E10 petrol with 10 % ethanol was used. Fuel vapour pressure of each sample was adjusted according to test temperatures to match summer or winter condition and ensure effortless start-up. Test results showed that the composition of the fuel had marked influence on emissions. The lower the test temperature was, the more distinctive were the differences. Based on the results, about -15 °C would be the lower limit of operation with "straight" E85 mixture composed ethanol and petrol. On the other hand the more "engineered" fuels performed much better, and allowed starting as low as at -20 to -25 °C. Cold start and driving was possible at equal level of unburned hydrocarbons and other unwanted emissions (aldehydes, ethanol) at an ambient temperature more than 10 °C lower compared to "straight" E85 fuel.