The Istituto Motori research activities concerning natural gas heavy duty engines

In this paper the potentialities of natural gas heavy duty engines, in both stoichiometric and lean burn configuration, are analysed in view of complying with future emission legislative limits. The main obstacle of lean burn solution is represented by the difficulty of simultaneously controlling NOx and HC, without worsening fuel consumption. However this engine offers the advantage of low thermal stress, similar to that of Diesel. The stoichiometric engine is a very promising solution to develop environmental friendly heavy duty vehicles, thanks to high efficiency of three-way catalytic converters, but in this case thermal stress and non optimal fuel consumption should be taken in consideration.