文档介绍：ARTICLE IN PRESS
Progress in Energy bustion Science 33 (2007) 272–309
ate/pecs
Soot processes pression ignition engines
Dale R. Treea,Ã, Kenth I. Svenssonb
aBrigham Young University, 435M CTB, Provo, UT 84602, USA
bEngine Product Development, Volvo Powertrain North America, 13302 Pennsylvania Avenue, Hagerstown, MD 21742, USA
Received 6 January 2005; accepted 17 March 2006
Available online 16 January 2007
Abstract
While diesel engines are arguably superior to any other power-production device for the transportation sector in terms
of efficiency, torque, and overall driveability, they suffer from inferior performance in terms of noise, NOx and particulate
emissions. The majority of particulate originates with soot particles which are formed in fuel-rich regions of burning diesel
jets. Over the past two decades, our understanding of the formation process of soot in bustion has transformed
from inferences based on exhaust measurements and laboratory flames to direct in-cylinder observations that have led to a
transformation in diesel bustion. In-cylinder measurements show the diesel spray to produce a jet which forms a
lifted, partially premixed, turbulent diffusion flame. Soot formation has been found to be strongly dependent on air
entrainment in the lifted portion of the jet as well as by oxygen in the fuel and to a lesser extent position and
structure of hydrocarbons in the fuel. Soot surviving bustion process and exiting in the exhaust is dominated by
soot from fuel-rich pockets which do not have time to mix and burn prior to exhaust valve opening. Higher temperatures
at the end bustion enhance the burnout of soot, while high temperatures at the time of injection reduce air
entrainment and increase soot formation. Using a conceptual model based on in-cylinder soot bustion
measurements, trends seen in exhaust particulate can be explained. The current trend in diesel engine emissions control
involves multi-bustion strategies which are tr