Abstract
•Using of 3 and 7vol.% n-butanol blends in SI engine is studied for the first time.•Engine performance and emissions depend on both engine speed and blend rates.•CO and UHC for blended fuels are maximum at 3000–3100r/min.•The higher the rate of n-butanol, the lower the emissions and performance.•This study strongly supports using low blend rates of n-butanol (<10vol.%) in ICE.
In this paper, exhaust emissions and engine performance have been experimentally studied for neat gasoline and gasoline/n-butanol blends in a wide range of working speeds (2600–3400r/min) without any tuning or modification on the gasoline engine systems. The experiment has the ability of evaluating performance and emission characteristics, such as break power, torque, in-cylinder pressure, volumetric efficiency, exhaust gas temperature and concentrations of CO2, CO and UHC. Results of the engine test indicated that using n-butanol–gasoline blended fuels slightly decrease the output torque, power, volumetric efficiency, exhaust gas temperature and in-cylinder pressure of the engine as a result of the leaning effect caused by the n-butanol addition; CO, CO2 and UHC emissions decrease dramatically for blended fuels compared to neat gasoline because of the improved combustion since n-butanol has extra oxygen, which allows partial reduction of the CO and UHC through formation of CO2. It was also noted that the exhaust emissions depend on the engine speed rather than the n-butanol contents.