Potential of n-butanol/diesel blends for CI engines under post injection strategy and different EGR rates conditions

摘要

Blending n-butanol and diesel fuels in combination with a post injection strategy could accomplish the target of ultra-low soot emissions. However, the introduction of n-butanol leads to increased NOx emissions. Exhaust gas recirculation (EGR) technology is considered a suitable means of inhibiting the formation of NOx. Little research has been conducted on post injection strategies in conjunction with the effects of n-butanol/diesel blends and different EGR rates on engine emissions and combustion performances. In this investigation, a turbocharged diesel engine is used to explore the effect of n-butanol and EGR rates on engine emissions and combustion performances. Further, to gain a better understanding of the effect of EGR rates on compression ignition engines with different fuels, the energy distribution of cycle fuel mass with different EGR rates and fuels is analyzed. The four test fuels were as follows: pure diesel (D100), diesel with 10% n-butanol addition (NB10), diesel with 20% n-butanol addition (NB20), and diesel with 30% n-butanol addition (NB30). The results show that the use of post injection has little impact on the ignition delay time and brake thermal efficiency (BTE), and reduces the emissions of CO, HC, NOx, and soot by 33.3%, 10%, 25%, and 50%, respectively. Under certain post injection strategies, the addition of n-butanol (10%, 20%, and 30%) produced significant reduction in CO and soot emissions. Within the range of 10% and 20% EGR, NB20 fuel can achieve a balance between combustion performance and emissions under certain post injection strategies. In addition, NB30 fuel has the lowest soot and CO emission energy proportion and highest exchange heat energy proportion.