Impacts of fuel stratification on particulate matter formation and properties during ACI Engine operation
Melanie DeBusk, NTRC-Oak Ridge National Laboratory
As multi-mode type engine combustion strategies are investigated as a pathway to increased vehicle fuel efficiency, a better understanding of particulate matter formation during the advanced compression ignition (ACI) modes and the resulting PM properties is of growing importance for mitigating PM emissions and/or developing emissions control strategies. ACI combustion strategies claim extremely low soot production while achieving high break thermal efficiencies (BTE). However, US regulated emissions are on particulate matter (PM) mass which can consist of soot and/or hydrocarbon based particulate known as elemental carbon (EC) and organic carbon (OC), respectively. The composition of PM mass from ACI combustion ranges from nearly 100% OC to a mix of EC and OC particulates as the extent of fuel stratification increases. How the mass, compositions and morphology of PM changes as fuel stratifies within the combustion chamber, and what this can tell us about PM formation will be presented. Impact of fuel properties and the level of exhaust gas recirculation (EGR) on particulate matter properties will also be explored.