Effect of Bioethanol-Gasoline Fuel Blends on an SI Engine Exhaust Emissions

In this paper, the effect of bioethanol- gasoline fuel blends on exhaust emissions of a four-cylinder spark ignition (SI) engine was investigated experimentally. Pure gasoline fuel was blended with various percentages of bioethanol (0, 20, 40, 60 and 85%), and the HC, CO, CO2 and NOX exhaust emissions were measured at different engine speeds and two throttle valve positions (full throttle and 50% throttle valve).The experimental results showed that as the ratio of bioethanol fuel is increased in the blend, the CO and HC emissions are decreased but CO2 and NOX are increased at two throttle valve positions. Also when the speed of engine was increased, the HC and CO2 emissions were decreased but CO and NOX emissions were increased. The statistical analysis indicated that the effect of bioethanol percentage in fuel blends on emissions at 5% level was significant.