Analysis of the highly premixed combustion attained by a late injection strategy in an HD diesel engine

The paper is focussed on the highly premixed combustion concept in diesel engines, whose main interest is the simultaneous reduction of nitrous oxides and soot emissions. The strategy for achieving this combustion concept has been retarding the injection process until the expansion stroke, thus avoiding instabilities in the auto-ignition. This experimental work has been focused on the combustion process description and also on the definition of pollutant emissions behaviour. The effect of the start of injection, the injection pressure and the boost pressure has been analysed. The results have confirmed the possibility of reducing both nitrogen oxides and soot emissions if the premixed combustion phase is sufficiently extended and the combustion is shifted towards the expansion stroke.