It is of great significance
to improve the performance of diesel
engines by adjusting the intake components and their distribution.
In this work, various proportions of exhaust gas recirculation (EGR)
gas and oxygen (O
2
) have been introduced to the intake
charge of a diesel engine and the effects of different intake components
and stratification conditions on pollutant emissions, especially for
particles, have been explored. The results show that the introduction
of O
2
into the intake charge is beneficial to alleviate
the deterioration of particles and hydrocarbon (HC) emissions caused
by high EGR rates. Compared with the pure air intake condition, the
introduction of moderate O
2
at high EGR rate conditions
can simultaneously reduce nitrogen oxides (NO
x
) and particles, when the intake oxygen content (IOC) is 0.2
and the EGR rate is 20%, the NO
x
and particles
are reduced by 45.66% and 66.49%, respectively. It is worth noting
that different intake components have a significant impact on the
particle size distribution (PSD) of diesel engines. In addition, the
in-cylinder O
2
concentration distribution formed by the
stratified intake is advantageous for further improving the combined
effect of NO
x
, particles and HC emissions
relative to the homogeneous intake. At a condition of 0.2 IOC and
20% EGR rate, the NO
x
, particles, and
HC emissions are about 8.8%, 14.3%, and 26% lower than that of intake
components nonstratification, respectively.