Investigation of Ethanol Spray From Different DI Injectors by Using Two-Dimensional Laser Induced Exciplex Fluorescence at Potential Cold-Start Condition

The spray evaporation of gasoline and ethanol fuel was investigated qualitatively through the use of the planar laser induced exciplex fluorescence (PLIEF) technique in a constant volume chamber. The effect of fuel temperature and ambient pressure on spray evaporation was identified over a range of conditions. Both a swirl injector and a multi-hole injector were examined for each of the two fuels. A coevaporative mixture of benzene and triethylamine (TEA) was used as a fluorescent seeding material to study the evaporation processes of ethanol fuel. A mixture of fluorobenzene (FB) and diethylmethylamine (DEMA) in n-hexane, which has been proved to be a suitable seeding material for LIEF measurement, allowed for the investigation of the evaporation processes of gasoline fuel mixture. Remarkable spray evaporation processes were observed for both gasoline and ethanol fuel by increasing fuel temperature or by reducing ambient pressure to a vacuum. Especially after achieving flash-boiling, the vapor distribution of multi-plume spray increases dramatically, and the vapor phase of spray from swirl injector gathers to the centerline of injector by increasing the superheated degree. The collapsing of both liquid and vapor phases of n-hexane is stronger than that of ethanol spray for both swirl and multi-hole injectors.