buletinul institutului politehnic din iaşi - Universitatea Tehnică ...

104 Ioan Hiticas et al.
3. Experimental Research
The experimental research was conducted in vehicle dynamics laboratory
from Faculty of Mechanics, Timişoara. For the experiments we analysed two
engine types: first type was the diesel engine, which equipped the urban
vehicles, and a second engine, a spark ignition engine, which equipped a
passenger car.
In this paper we present the real situation of diesel engine which
equipped the vehicle in urban transportation (Koerner & Klopatek, 2002), and
we monitored the exhaust gases to identify the principal harmful elements, with
adverse health effect.
In compression ignition engines case, we realised measurement for
particulate matter and opacity. Vehicles used for experimental research was an
urban bus, Mercedes, model which fit almost the entire urban city fleet. The
vehicles are equipped with diesel engines (Wallington T.J. et al., 2008); model
MO45LhA, 11 litres displacement, and supercharged, nominal power 183
kW/2100 rpm, and emission standard were Euro III. Usually a diesel engine
emitted through tailpipe different harmful species, like HC, NOx, and others,
including particulate matter which composed the soot. Another reference on this
engine is the degree of smoke and the opacity, which is in correlation with
linear absorption coefficient, k, measured through opacimeter.
Tested vehicle have run a travel distance of 3500 km, divided in five
segments. First segment was 1323 km distance, followed by other 4 segments,
presented in Table 1. For the first segment, we make measurements with the
opacimeter, having k = 0.23 m -1 , or Hartridge Standard Unit, HSU = 0.90 %,
resulting PT (particulate matter) = 0.05 [g/m 3 ], for this first segment.
Table 1
Evolution of particulate matter and opacity
Nr. Travel distance, km k, m -1 HSU, % PT, g/m 3
1 1323 0.23 0.90 0.05
2 1741 0.31 0.86 0.07
3 2322 0.44 0.81 0.09
4 2936 0.26 0.88 0.06
5 3465 0.38 0.83 0.08
The opacity is expressed through linear absorption coefficient, K, through
the equation
1 1−N
k = ln ,
(3)
L 100
where: k – Linear absorption coefficient; L – Effective length of a column of
homogeneous gas, m.