Effects of oxygen concentration on combustion and emissions of diesel engine are investigated by experiment.The intake oxygen concentration is controlled by adjusting CO2.The results show that very low levels of both soot and NOx emissions can be achieved by modulating the injection pressure,tim-ing,and boost pressure at the low levels of oxygen concentration.However,both CO and HC emissions and fuel consumption distinctly increase at the low levels of oxygen concentration.The results also indicate that NOx emissions strongly depend on oxygen concentration,while soot emissions strongly depend on injection pressure.Decreasing oxygen concentration is the most effective method to control NOx emissions.High injection pressure is necessary to reduce smoke emissions.High injection pres-sure can also decrease the CO and HC emissions and improve engine efficiency.With the increase of intake pressure,both NOx and smoke emissions decrease.However,it is necessary to use the appro-priate intake pressure in order to get the low HC and CO emissions with high efficiency.
