Role of fuel properties and piston shape in influencing soot oxidation in heavy-duty low swirl diesel engine combustion
Artikel i vetenskaplig tidskrift, 2019

The presented study evaluated effects on soot emissions of important diesel fuel properties (e.g. volatility T95, hydrogen to-carbon ratio H/C and oxygen content O/C) in a heavy-duty, low-swirl, direct injection diesel engine operated with cooled exhaust gas recirculation to control the emissions of nitrogen oxides. Variation of injection pressure was conducted in three representative operation points in the single-cylinder engine including conventional and wave piston bowl types. Additionally, detailed optical combustion studies were performed in a high pressure/high temperature combustion chamber with an engine-like flame-wall interaction geometry. The fuel properties mainly influenced parameters relating to events near the nozzle, such as the ignition delay, flame lift-off distance and spray air entrainment. Oxygenation of the fuel reduced soot formation (a known effect of spray-jet dilution), but the fuels’ H/C and T95 also influenced soot emissions. Viscosity, heating value and density, treated as secondary fuel parameters, affected the injected fuel's kinetic energy, and hence mean flow field and local turbulent mixing late in the combustion cycle. The results suggested that fuel effects on soot oxidation during late phases of combustion are mainly governed by parameters related to the fuel injection profile under the specific cylinder gas conditions. With an oxygenated fuel, flow structures (local turbulent side vortices) which are typical for the investigated engine type were found to form in a similar way as with a reference fuel. Hence, improved internal flow using a wave piston in combination with a low-sooting oxygenated fuel gave additional reductions in net soot emissions.

Diesel combustion

Fuel properties

Soot oxidation

Late cycle mixing

Wave piston

Piston bowl shape

Författare

Jan Eismark

Volvo Cars

Chalmers, Mekanik och maritima vetenskaper, Förbränning

Magnus Christensen

Volvo Cars

Mats Andersson

Förbränning och sprejer

Anders Karlsson

Volvo Cars

Chalmers, Mekanik och maritima vetenskaper, Förbränning

Ingemar Denbratt

Förbränningsmotorer och framdrivningssystem

Fuel

0016-2361 (ISSN)

Vol. 254 115568

Ämneskategorier

Energiteknik

Annan kemiteknik

Strömningsmekanik och akustik

DOI

10.1016/j.fuel.2019.05.151

Mer information

Senast uppdaterat

2019-12-02