Journal Article
Cold Start on Diesel Engine: Is Low Compression Ratio Compatible with Cold Start Requirements?
2008-04-14
2008-01-1310
Future emission standards for Diesel engine will require a drastic reduction of engine-out NOx emissions with very low level of particulate matter (PM), HC and CO, and keeping under control fuel consumption and combustion noise. One of the most promising way to reach this challenge is to reduce compression ratio (CR). A stringent limitation of reducing Diesel CR is currently cold start requirements. Indeed, reduction of ambient temperature leads to penalties in fuel vaporization and auto ignition capabilities, even more at very low temperature (-20°C and below). In this paper, we present the work operated on an HSDI Common rail Diesel 4-cyl engine in three area: engine tests till very low temperature (down to -25°C); in cylinder imaging (videoscope) and CFD code development for cold start operation. First, combustion chamber is adapted in order to reach low compression ratio (CR 13.7:1).