Effect of ethanol addition on the performance and exhaust emissions of a spark ignition engine

The depletion of fossil fuel availability and increase of pollution due to the use of fossil fuels have forced the researcher to find a renewable-friendly energy source. One of the potential replacements is alcohol based fuel. This present study investigated experimentally the influence of ethanol addition on the engine performance, in terms of effective power, brake specific fuel consumption, and exhaust emissions of a gasoline spark ignition engine. The engine used in the research was a 4-stroke single cylinder, indirect injection system with engine capacity of 124.8cc, and compression ratio of 9.3:1. The experiments were conducted at eight different engine speeds ranging from 1500 rpm to 5000 rpm and 10 types of gasoline-ethanol mixtures (E10 to E100). The result showed that the effective power decreased with the increase of ethanol in the fuel blends for all variations of engine speed. Leaning effect of ethanol addition in the blend fuel caused the CO emissions to decrease greatly as well as the HC emissions. On average, gasoline engine fueled by pure ethanol reduced the CO emission level by more than 60 % in volume compared to the engine with gasoline fuel. On average, the maximum power of the engine with fuel blend was obtained at engine speed of around 2500 to 3000 rpm. For higher ethanol content on the fuel blend, the optimum shift to the lower engine speed. It can be concluded that engine operation with ethanol content on the fuel performed better in the lower engine speed.