Experimental Investigation of Different Hydrous Ethanol-Gasoline Blends on a Flex-Fuel Engine 2010-36-0469

In Brazilian market, Flex-Fuel vehicles represented over 90% of new light-duty vehicles sold in 2009. These vehicles can use gasoline blended with anhydrous ethanol (20 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. An experimental investigation was done to study fuel consumption, emissions and in-cylinder pressure data of a Flex-Fuel Otto engine, 1.4 L, 4 cylinders. It used gasoline with 22% of anhydrous ethanol as a reference fuel (E22). E22 was blended with different hydrous ethanol contents such as 50% (H50) and 80% (H80), also a 100% hydrous ethanol H100) was used. The main fuel properties were analyzed as part of this work. 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, and high load with rich mixture for four different engine speed conditions. In-cylinder pressure data was analyzed by using a special data acquisition system and a piezoelectric pressure sensor installed on the spark plug. Some combustion characteristics, such as combustion duration, indicated mean effective pressure (IMEP) and others were calculated based on in-cylinder pressure curve data. Test results were handled by the STATISTICA® software that calculated different regression curves for each output variable, based on torque, speed and ethanol content.