Emissive Behavior of a Heavy-Duty SI Gas Engine During WHTC

In the arduous aim to reduce petroleum fuel consumption
and toxic emissions, gaseous fuels can represent an alternative
solution for heavy duty applications with respect to
conventional liquid fuels.
At the same time, the imposition of more stringent
emission regulations in the transport sector, is a crucial aspect
to be taken into account during the development of future
gas engines.
Aim of the present paper was to characterize a heavy
duty spark ignition engine, under development for Euro VI
compliance, with a particular focus on exhaust particulate
emissions. In this sense, the engine was installed on a
dynamic test bench, accurately instrumented to analyze
combustion evolution, performance and exhaust pollutant
emissions, along the World Harmonized Transient
Cycle (WHTC).
The emissions diagnostic devices included a gas analysis
system for the measurement of regulated species, a photoacoustic
sensor and a fast particulate spectrometer for on-line
soot, particle number (PN) and particle size measurements,
during the transient engine tests. The system layout comprised
also a Thermodenuder to provide information on the volatile
species contribution to particles emissions.
The results reveal a correlation of soot and PN emissions
with some specific phases of the test cycle, providing some
clues on the source of particles emissions.
The paper improves the literature in this field, at present
still limited, providing useful information on soot and PN emissions
from a heavy duty gas engine at the state of art technology.