Chemistry Reference
In-Depth Information
Table 3 Typical exhaust after-treatment for diesel light-duty vehicles
Emission standard
Emission control
SCR
a
Stage
Date
EGR
DOC
DPF
Euro 1 and earlier
-
-
-
-
Euro 2
1996
(
✓
)
✓
-
-
Euro 3
2000
✓
✓
(
✓
)
-
Euro 4
2005
(
✓
)
-
✓
✓
Euro 5
2009
-
✓
✓
✓
Euro 6
)
Brackets correspond to application to some vehicles of the particular emission standard only
a
2014
(
✓
✓
✓
✓
SCR or NO
x
trap
Table 4 Typical exhaust after-treatment for diesel heavy-duty trucks
Emission standard
Emission control
DI
a
HPI
b
EGR
c
DOC
c
Stage
Date
DPF
SCR
Pre-Euro I
-
-
-
-
-
Euro I
1993
-
-
-
-
✓
Euro II
1996
-
-
-
✓✓
Euro III
2000
-
(
)
-
✓✓
✓
Euro IV
2005
(
)
(
)
-
(
)
✓✓
✓
✓
✓
Euro V
)
Euro VI 2014
✓✓✓✓✓✓
Brackets correspond to application to some vehicles of the particular emission standard only
a
Direct injection
b
High-pressure injection
c
EGR and DOCs were used in buses earlier than stated in the table, and in some cases as early as
the Euro I stage
2009
(
)
-
(
✓✓
✓
✓
✓
the two systems in terms of NO
x
control efficiency as a function of exhaust
temperature. Figure
5
shows an example of the emission behaviour of vehicles
equipped with the two systems. EGR performs much better at low speeds, whereas
SCR becomes more efficient at high speeds as exhaust gas temperature increases.
The actual performance of the two systems in real-world terms will depend on the
operational patterns of vehicles, such as the frequency of use in urban or highway
situations.
4.3 Fuel Quality and Alternative Fuels
Engine and vehicle technologies normally achieve their best emissions perfor-
mance with high quality fuels. One property on which a great deal of attention
has focussed is the sulphur content, partly because of the need to reduce PM and
SO
2
emissions and partly because fuel sulphur has an adverse effect on certain types
of engine and exhaust after-treatment technology. In Europe the controls on fuel
