This study uses on-board measurement systems to analyze
emissions from a diesel engine vehicle during the cold start
period. An in-vehicle FTIR (Fourier Transform Inferred)
spectrometer and a Horiba on-board measurement system (OBS-1300)
were installed on a EURO3 emission-compliant 1.8 TDCi diesel van,
in order to measure the emissions. Both regulated and non-regulated
emissions were measured, along with an analysis of the NO/NO₂
split. A VBOX GPS system was used to log coordinates and road speed
for driving parameters and emission analysis. Thermal couples were
installed along the exhaust system to measure the temperatures of
exhaust gases during cold start. The real-time fuel consumption was
measured. The study also looks at the influence of velocity on
emissions of hydrocarbons (HCs) and NOx.
The cold start period of an SI-engine-powered vehicle, was
typically around 200 seconds in urban driving conditions. The
results of this research show that the cold start period for the
diesel engine is shorter than that for the SI engine. Emissions of
CO, NO, NO₂, formaldehyde and total hydrocarbons (THCs) were higher
during the cold start period than the warmed up period. The
magnitude of increase during the cold start was smaller than SI
engines. NOx emissions under real-world driving conditions were
well above the legislated values. The study of velocity and
emissions also found a correlation between emissions of HCs and NO
with vehicle velocity, showing a trend of higher speed alongside
higher emissions.