Applicability of Various EGR Strategies in a Multi-cylinder Diesel Engine

- Effect of Combining HPL-EGR and LPL-EGR Systems -

Abstract

The effect of combining high pressure loop (HPL-) and low pressure loop (LPL-) EGR systems on engine performance and emission characteristics were investigated using a multi-cylinder diesel engine under steady-state conditions. At low load, increasing HPL-EGR rate causes higher soot emission whereas increasing LPL-EGR rate causes higher fuel penalty. To solve this problem, combining HPL- and LPL-EGR systems at low load can reduce exhaust emissions without fuel penalty. At high load, in contrast, since pumping loss is low effect on fuel consumption, increasing LPL-EGR rate with higher boost pressure can reduce NOx and soot emissions simultaneously.