Effect of Injection Strategy on the Combustion and Exhaust Emissions Characteristics of Biodiesel-Ethanol Blend in a DI Diesel Engine

An experimental investigation was performed on the effect of injection strategy on the combustion, exhaust emissions characteristics and the particle size distribution in a direct-injection (DI) compression ignition engine fueled with biodiesel-ethanol blended fuel. The results obtained from the experiment of the particle distributions for the blended fuel are compared to that of diesel fuel. In addition to the distribution of the particles, exhaust emissions such as oxides of nitrogen (NO_x), hydrocarbon (HC), and carbon monoxide (CO) emissions and combustion characteristics under different engine operating parameters were investigated. The engine operating parameters in terms of injection timing and injection strategy were varied to investigate the combustion and emission reduction of biodiesel and ethanol blended fuel. The results show that multiple injection strategy of biodiesel-ethanol blended is beneficial to reduce NO_x emissions significantly without significant increase of soot emission. In multiple injection strategy, as the first injection mass was increased, the larger size particles were increased, however total numbers of particles were reduced. Biodiesel-ethanol blended fuel reduced particle concentration of relatively large size compared to the particles concentration of ULSD. Moreover, dramatically lower NO_x and soot emissions were found at the blend fueled with engine at the same injection condition.