The Influence of Fuel Properties on Particulate Number Emissions from a Direct Injection Spark Ignition Engine 2013-01-1558
The use of direct injection spark ignition (DISI) engines for
passenger cars has increased; providing greater specific
performance and lower CO₂ emissions. DISI engines, however, produce
more particulate matter (PM) emissions than Port-Fuel-Injected
(PFI) engines. Forthcoming European exhaust emissions legislation
is addressing concerns over health effects of PM emissions.
Accordingly, research into PM emission formation has increased.
A model developed by Aikawa et al., (2010) for PFI engines
correlated PM number emissions with the vapor pressure and the
double bond equivalent (DBE) of the components of the fuel. However
there was no independent control of these parameters. This study
investigates a particulate emissions index for DISI engines.
A single-cylinder optical access Spray-Guided DISI engine was
used to develop a Particulate Matter Number emissions Index (PN
index) - modified from the PM index using industry standard
measurements - through the use of model and commercially available
Model fuels were designed using Raoult's law and UNIFAC such
that the DBE and vapor pressure of the fuel mix could be
Engine tests were conducted, independently varying the DBE and
the vapor pressure of the fuel. PM number emissions were measured
using a Cambustion DMS500, the results were analyzed alongside
observations of the fuel spray to investigate the PN index.
The PN index has also been used to evaluate emissions from two
commercially available EN228 fuels. The results demonstrate that
the trend of the PN index is followed both with model fuels and