Abstract
Effects of O_2 concentration and injection duration on combustion and emission characteristics of diesel spray in a high temperature and high pressure vessel was experimentally examined under low O_2 concentration ambient. It is confirmed that the fuel injection duration has large effect on the shape of heat release rate. As the decrease of injection duration, the shape changed from the normal diesel combustion like one to the smooth heat release rate curve with only one peak which is qualitatively similar to the effect of O_2 concentration. Under the very low O_2 concentration condition, the combustion duration becomes extremely longer as the increase of injection duration which is primarily due to the slow heat release during the later phase of combustion. The CO emission rate increases with the decrease of O_2 concentration and with the increase of injection duration. The NOx emission rate dramatically decreased with the decrease of O_2 concentration, however there existed an injection duration which leads to the maximum NOx emission rate.
