Abstract：Charged with variable oxygen and nitrogen components as intake air, the combustion features and emission regulations of a diesel engine were analyzed. The results show that the effect of enriched nitrogen on prolonging ignition delay appears more evidently than that of enriched oxygen on shortening ignition delay. The increasing rates of all emissions show second polynomial relationship with the increasing rate of intake oxygen. From the state of nitrogen enrichment, with the increasing of intake oxygen content, the ignition delay is decreased, and the cylinder peak pressure and the maximum rate of pressure rise are increased. At the state of oxygen enrichment, the effects of oxygen increasing on the reduction of HC, CO and smoke are weakened gradually. At the state of nitrogen enrichment, HC, CO and smoke are worsened sharply. NOx emissions behave a rapid rise at oxygen enrichment state but with slow decline at nitrogen enrichment state. Restricted by oxygen providing, the influence of intake oxygen volume fraction variation on CO and smoke emissions is enhanced at large load. At small load, the intake oxygen volume fraction has marked impact on in-cylinder temperature, which leads to more sensitivities of HC and NOx emission.
2016, Vol. 37 
