For this reason a computational investigation is conducted
on a heavy duty DI single cylinder diesel test engine
capable of operating at high peak combustion pressures [7].
Under EU project HEDE advanced injection timing was
used to improve its brake specific fuel consumption (bsfc)
that obviously had a negative impact on NOx emissions.
To control NOx, cooled EGR was considered using a fixed
temperature for all test cases examined. In the present work
are examined various EGR temperatures to determine
its effect on the combustion and pollutant formation
mechanisms. The study, due to space limitations, is
conducted at full load and various engine speeds were the
highest EGR mass flow rates are required. The theoretical
study is conducted using an existing 3D multi-zone model
[8,9], appropriately modified [4] to include the effect of
EGR percentage and temperature. For the analysis boost
pressure and injection timing were kept constant whereas
engine speed, EGR percentage and EGR temperature were
used as parameters for the calculations. As shown EGR
temperature has a detrimental effect on brake engine
efficiency and soot emissions while it has a small effect on
NO emissions in the EGR temperature range examined. A
more significant effect would exist if the EGR upper
temperature range was increased (hot EGR). As revealed,
reduction of EGR temperature (EGR cooling) is beneficial
for both bsfc and soot the effect depending on engine speed
and EGR rate considered.