Performance characteristics of a single cylinder spark ignition engine fuelled with ethanol–petrol blends at constant engine speed

ABSTRACT Performance and exhaust emission analyses of a single cylinder spark ignition engine fuelled with an extended range of ethanol–petrol blends were carried out successfully at constant engine speed conditions. Ethanol produced from Nigerian feedstock was blended with petrol at different proportions by volume. In order to establish a baseline for comparison, the engine was first run on neat petrol. The engine performance parameters (brake specific fuel consumption, brake mean effective pressure and brake thermal efficiency) and the exhaust emission parameters (CO, HC, CO2 and O2 emissions) were determined for each blend of fuel at different engine external load and at a particular engine speed. The test results showed that addition of ethanol to petrol causes an improvement in engine performance and significant reduction in exhaust emissions. At 2500 rpm, E30 recorded the maximum thermal efficiency of 43.20% followed by E20 with thermal efficiency of 42.8% while at 3500 rpm, the maximum efficiency of 37.8% was recorded for both E20 and E30 fuels. The maximum thermal efficiency for petrol fuel at 2500 rpm and 3500 rpm were 24.12% and 25% respectively. E30, E20, E15 and E10 blends showed respectively an increment of 7.25%, 14.50%, 10.14% and 4.35% in combustion efficiency compared to that of petrol. Generally, the CO and HC emissions were significantly reduced through blending of petrol with ethanol. Ethanol and its blends with petrol exhibited performance characteristics trends similar to that of petrol thus suggesting them as suitable alternative fuels for spark ignition engines.