High Concentration Ethanol Effect on SI Engine Emission 2010-01-1268
From the energy security and CO2 reduction point of view, much attention has been paid to the usage of bio-fuel. Recently, highly concentrated ethanol is used in some areas (“E85”; 85% ethanol and 15% gasoline in North America and Sweden, and “ethanol”; 93% ethanol and 7% water in Brazil). In these regions, Flexible Fuel Vehicles FFVs are being introduced that are capable of using fuels with a wide range of ethanol concentrations. Advantages of highly concentrated ethanol in internal combustion engine applications are higher thermal efficiency obtained due to higher octane number, and a reduction of nitrogen oxides due to lower combustion temperatures On the other hand, the latent heat of vaporization for ethanol is greater than gasoline, causing poor cold startability and high NMOG emissions.
This paper examines the effect of highly concentrated ethanol on exhaust emissions at cold start in a SI- engine. In first, by using gas sampling and computational simulation in-cylinder at the peak compression, quantity and composition of evaporated highly concentrated ethanol fuel are analyzed at cold temperatures, which is a determining factor for startability and exhaust emissions. And, technical guidelines for reducing exhaust emissions are defined from the viewpoints of fuel properties requirements such as concentrations and saturated vapor pressures of ethanol, and fuel evaporations improvement by utilizing variable valve train and heating device.