Combustion characteristics, performance and emissions of an acetone/n-heptane fuelled homogenous charge compression ignition (HCCI) engine

Recently, there has been renewed interest in homogenous charge compression ignition (HCCI) engines due to their high thermal efficiency and low NOx and particulate matter. However, knocking and misfiring are the classic problems in HCCI engines. The present study aimed to explore the effects of acetone addition into the n-heptane on the combustion, performance and emission characteristics of HCCI engine. Four different fuels were used in this research: N100 (pure n-heptane), A20N80 (acetone 20% - n-heptane 80%), A40N60 (acetone 40% n-heptane 60%), A60N40 (acetone 60% - n-heptane 40%). The experiments were carried out at 1000 rpm, 60 degrees C inlet air temperature and various lambda values (between 1.61 and 2.82). The research presented here confirms that in-cylinder pressure and heat release rate significantly decreased with the usage of A60N40 fuel blend. Besides, knocking disappeared with increasing amount of acetone into the mixture owing to the high octane number of acetone. The brake torque increased by 53.5% and specific fuel consumption (SFC) was lower by 44.8% for A60N40 compared to n-heptane at lambda = 2.1.