Different Hydrous Ethanol-Gasoline Blends - FTIR Emissions of a Flex-Fuel Engine and Chemical Properties of the Fuels 2011-36-0080

In Brazilian market, Flex-Fuel vehicles represented over 85% of new light-duty vehicles sold in 2010. These vehicles can use gasoline blended with anhydrous ethanol (18 to 25% v/v), 100% of hydrous ethanol (contains from 6,2 to 7,4% w/w of water) or any blend of these fuels.

Some studies regarding Flex-Fuel technology are being made in Brazil, but there are not many published information about fuel properties of different ethanol-gasoline blends. Also, it is important to better understand emissions of aldehydes, unburned ethanol and total hydrocarbons of different ethanol blends on gasoline.

A Flex-Fuel engine, 1.4 l, 4 cylinders was tested on a dynamometer. A FTIR (Fourier Transform Infrared analyzer) bench measured aldehydes, unburned ethanol and total hydrocarbons. It was used Gasoline with 25% of anhydrous ethanol was used as a reference fuel (E25). E25 was blended with different hydrous ethanol contents such as 30% (H30), 50% (H50), 80% (H80) and 100% (H100). To control the engine operation, a programmable ECU (Engine Control Unit) was used, allowing spark timing calibration either for maximum break torque (MBT) or to keep the engine below the knocking limit. Operating conditions included partial load with stoichiometric air-fuel ratio, for three different engine speed conditions. Test results were handled by the STATISTICA® software that calculated a 95% confidence interval for each operating condition. The main physical properties of the different blends were analyzed as part of this work, including H/C and O/C molar ratio, net heating value and others.

The emissions results presented a reduction trend for CO, NMHC and NOx, a trend of increase of aldehydes and unburned ethanol and no significant changes for CO2.