An Experimental Study On Turbocharged Direct Injection Engine With Butanol-Gasoline Blend Fuels

Facing with double pressure of the increasingly serious environment pollution and the word energy crisis, the search for economically viable and environmentally friendly green alternative fuels is particularly important. This paper mainly studies the effects of n-butanol-gasoline oxygen fuel on combustion, power, fuel economy and emissions in a turbocharged direct injection gasoline engine through changing butanol ratio (Bu15, Bu30, Bu50) and ignition timing. And the results were compared with burning pure gasoline.The effect of n-butanol ratio results showed that:At the part loads and closed loop control area, as n-butanol injection ratio increased, the ignition delay and combustion duration shortened, the main heat release time advanced, and at the same time the speed of combustion reaction accelerated, the peak of combustion pressure and heat release rate increased. Although KP_PKavg increased, but the combustion cyclic variability decreased as n-butanol injection ratio increased, resulting in comprehensive knocking tendency weaken. At fuel economic and emissions part, with the n-butanol injection ratio increased, the brake specific fuel consumption increased, but the brake thermal efficiency improved. Additionally, before Three Way Catalysts, with the increase of n-butanol volume ratio, the emissions of THC and CO increased, but NOx decreased significantly, while the exhaust temperature before turbocharger also decreased. And with the load increased, the combustion and emissions parameters changed more obvious. At full load and open loop control areas, the combustion process parameters and the changed of emissions were similar with partial load, with the rising rates of n-butanol ratio, the brake specific fuel consumption increased, particularly the brake thermal efficiency of Bu15blend fuel had improved, but Bu30and Bu50were slightly lower, but the power and torque increased with n-butanol ratio raised. In addition, the physical and chemical properties of the n-butanol had obvious effect on knock tendency, compared with E10, the KP_PKavg of Bu50increased significantly.With increased ignition timing rates, compared with Bu00, the combustion parameters and emissions of50%n-butanol-gasoline fuel results showed that:Bu50and Bu00shared the same trend trends in combustion and emissions, the maximum cylinder pressure and heat release rate rised, combustion reaction speeds accelerated, the ignition delay and combustion duration shortened, the main heat release time advanced, and at the same time combustion cyclic variability decreased. Advancing ignition timing, the combustion process becomes better, energy and power conversion efficiency also increased when closed to the knocking boundary, the brake specific fuel consumption decreased, but the brake thermal efficiency would become better. Additionally, with the ignition timing advanced, before Three Way Catalysts, THC emissions increased, CO emissions basically unchanged, the exhaust temperature before turbocharger also decreased. Also compared with pure gasoline, Bu50emissions of NOx unchanged,and at the same time NOx and exhaust temperature were lower than BuOO.In summary, burmed a large volume proportion of n-butanol-gasoline oxygen fuel in direct injection gasoline engine, with ensured engine power constant, could improve the brake thermal efficiency and combustion stability. Simultaneously, combined with the earlier ignition timing, could improve thermal efficiency at the most and optimize engine fuel economy, particularly in the combustion of gasoline equivalent control region. This study will provide reference value for using of the efficient and clean n-butanol fuel in gasoline engine.