Influence of post-injection strategy on combustion process and emission characters at low load working condition in light-duty diesel engine

Taken a light-duty diesel engine as prototype, the influences of post-injection on NOx and soot emission characters, combustion process and fuel consumption were discussed at the operating conditions of low load rate with common speed of 1600 r · min-1. The results show that internal cylinder temperature rises again in the later of main combustion process due to post-injection. With the increasing of the post-injection fuel quantity, the main combustion section cylinder pressure, the maximum combustion temperature, the average combustion temperature and the peak value of the main combustion heat release rate are all gradually decreased. The main combustion section cylinder pressure and the peak combustion heat release rate increase slightly with the increasing of the post-injection interval angle, while the average combustion temperature decreases. At the condition of low load rate, NOx and soot emissions can be efficiently reduced by post-injection and gradually decreased by the increase of post-injection fuel quantity. With the increasing of post-injection interval angle, the NOx emission gradually decreases and the soot emission shows an upward trend after the initial decrease. The fuel consumption is increased by post-injection and the increasing of post-injection fuel quantity and post-injection interval angle.