Abstract
An experimental investigation on the combustion and controllability of the partially premixed combustion (PPC) fueled with n-butanol was conducted on a modified single-cylinder compression ignition engine. The effects of engine loads, intake pressure, exhaust gas recirculation (EGR), and two-stage injection strategy were studied. The results show that the controllability of the n-butanol PPC combustion is poor, which is even worse under low load. In addition, the controllability of the n-butanol PPC combustion is significantly sensitive to the EGR rate and a high EGR rate will result in the poor controllability, and it can be improved when appropriate small proportion of EGR is adopted. However, the controllability can be improved and high peak pressure rise rate (PPRR) can be reduced through adopting a high intake pressure, which is quite effective under the low-load condition. Furthermore, the deterioration of the controllability at a high EGR rate can also be improved by increasing the intake pressure. Meanwhile, compared with a single injection strategy, the adoption of the two-stage injection strategy has a remarkable effect on improving the controllability of the n-butanol PPC combustion, which however, leads to a slightly lower indicated thermal efficiency due to the longer combustion duration.