The challenges and strategies of butanol application in conventional engines: The sensitivity study of ignition and valve timing

The study approach of this paper is to combine experiment and simulation on using butanol as fuel in gasoline engine. First, experiments were performed under full load on a single cylinder spark ignition engine fueled with 35%vol butanol–gasoline blend and the pure gasoline, respectively. The performance and operating parameters were measured. The experimental results showed that with the butanol addition, the ignition timing could be advanced without obvious knocking for higher combustion efficiency. The engine presented superior performance in power, fuel consumption, HC and CO emissions, but deteriorated the NOx emissions largely. Then, a GT-Power simulation model was set-up and calibrated by experimental data. Therefore, the simulation model could be used to study the valve timing impact on engine performance. The simulation results indicated that the enlargement of overlap presented a good “trade-off” effect, such as, decreased emissions (especially for NOx), without deteriorating the torque and fuel consumption too much (except for extremity speeds of 3000rpm and 8500rpm, which are not frequently-used in real road driving). The results also indicated that the HC and CO emissions depend more on the fuel properties. The power and NOx emissions depend more on the operating parameters. And the fuel consumption is in between.