Fuel equivalence ratio and EGR impact on premixed combustion rate and emission output, on a Heavy-Duty Diesel engine

This study aims to show how both NOx and soot are affected by EGR dilution when constant, as well as variations in equivalence ratio is applied together with multiple injection strategies.

Experiments were conducted in a single cylinder heavy duty research engine. The effects of both EGR and equivalence ratio on partly premixed combustion were investigated. Multiple injections strategies were combined with high EGR levels and lean mixtures.

Multiple injections were used to control the combustion phasing and the level of the premixed combustion rate. The diesel combustion conditioning by means of premixed combustion rate, EGR level and oxidant equivalence ratio, leads to low engine emissions. In the load range and configuration tested, emission levels below future emission standards e.g. EURO V have been shown, with no BSFC penalty or exhaust aftertreatment.