Effects of injection strategies on combustion and emission characteristics of a common-rail diesel engine fueled with isopropanol-butanol-ethanol and diesel blends

Abstract

This study is aimed to investigate the performance, combustion, and emissions of a common-rail diesel engine fueled with IBE and diesel blends. Two blends of IBE and diesel fuel, denoted as IBE15 (15% IBE and 85% diesel in volume) and IBE30 (30% IBE and 70% diesel in volume), were tested under different injection strategies. The experimental results show that compared with single injection, the in-cylinder pressure and heat release rate curves (HRR) for all the tested fuels under double injection cases are less severe. That is to say, a pilot injection can reduce knocking combustion and ringing intensity when blending a high ratio of IBE into diesel. Furthermore, double injection is helpful in improving both engine performance and economy for all the tested fuels, especially for IBE30. For almost all the tested conditions, both IBE15 and IBE30 present a potential to reduce soot emissions but increase NOx emissions. A pilot injection is favorable to reduce NOx emissions but causes the soot emissions to increase. Results also show that the flame lift-off length of IBE30 is much longer than that of pure diesel. This feature may result in better air-fuel mixing, which then contributes to reduce soot emissions.