The Influence of Ethanol Blending in Diesel fuel on the Spray and Spray Combustion Characteristics

摘要

The influence of ethanol blending in Diesel fuel on the spray and spray combustion characteristics was investigated by performing experiments in an optically accessible high-pressure/high-temperature spray chamber under non-evaporating, evaporating and combusting conditions. Three fuels were investigated: (1) Diesel - a European Diesel based on the EN590 standard; (2) E10 - a blend of Diesel containing 10% ethanol and 2% emulsion additive; and (3) E20 - a blend of Diesel containing 20% ethanol and 2% emulsion additive. A constant gas density of 24.3 kg/m~3 was maintained under non-evaporating (30℃, 21.1 bar), evaporating (350℃, 43.4 bar), low combustion temperature (550℃, 57.3 bar) and high combustion temperature (600℃, 60 bar) conditions. A single-hole injector with a nozzle diameter of 0.14 mm was used and injection pressure was held constant at 1350 bar. Various optical methods were used to characterize the non-combusting and combusting sprays. Despite the differences in the fuels' compositions, they did not differ significantly with respect to their liquid phase spray penetrations or cone angles under non-evaporating or evaporating conditions. However, under combusting conditions, reducing the ambient temperature increased the ignition delay and delayed the onset of soot formation for all fuels. Under equivalent combustion conditions, E10 and E20 had longer ignition and soot formation delays than Diesel. As the ethanol content of the fuel was increased from 0% to 20%, the lift-off length increased and the detectable soot luminescence decreased.