Report - DCE - Nationalt Center for Miljø og Energi

For catalyst vehicles the cold extra emissions are found from:
&( = β ⋅ β ⋅ 1 ⋅ 0 ⋅ () ⋅ ( &(U
−1)
,
where βred = the β reduction factor.
,
,
For CH4, specific emission factors for cold driven vehicles are included in
COPERT IV. The β and βred factors for VOC are used to calculate the cold
driven fraction for each relevant vehicle layer. The NMVOC emissions during
cold start are found as the difference between the calculated results for
VOC and CH4.
For NH3, specific cold start emission factors are also proposed by COPERT
IV. For catalyst vehicles, however, just like in the case of hot emission factors,
the emission factors for cold start are functions of cumulated mileage
(emission deterioration). The level of emission deterioration also relies on
the content of sulphur in the fuel. The deterioration coefficients are given in
EMEP/EEA (2009), for the corresponding layer. For cold start, the cut-off
mileage and sulphur level interval for hot engines are used, as described in
the deterioration factors paragraph.
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For each year, evaporative emissions of hydrocarbons are simulated in the
model as hot and warm running losses, hot and warm soak loss and diurnal
emissions. The calculation approach is the same as in COPERT III. All emission
types depend on RVP (Reid Vapour Pressure) and ambient temperature.
The emission factors are shown in Ntziachristos et al. (2000).
Running loss emissions originate from vapour generated in the fuel tank
while the vehicle is running. The distinction between hot and warm running
loss emissions depends on engine temperature. In the model, hot and warm
running losses occur for hot and cold engines, respectively. The emissions
are calculated as annual mileage (broken down into cold and hot mileage totals
using the β-factor) times the respective emission factors. For vehicles
equipped with evaporation control (catalyst cars), the emission factors are
only one tenth of the uncontrolled factors used for conventional gasoline vehicles.
, ,
5 = 1 ⋅ 0 ⋅ (( 1−
β ) ⋅ +5 + β ⋅:5)
,
,
,
Where R is running loss emissions and HR and WR are the hot and warm
running loss emission factors, respectively.
In the model, hot and warm soak emissions for carburettor vehicles also occur
for hot and cold engines, respectively. These emissions are calculated as
number of trips (broken down into cold and hot trip numbers using the βfactor)
times respective emission factors:
0
,
6 ,
= 1 ,
⋅ ⋅ (( 1−
β ) ⋅ +6 + β ⋅:6)
O
Where S C is the soak emission, ltrip = the average trip length, and HS and WS
are the hot and warm soak emission factors, respectively. Since all catalyst
vehicles are assumed to be carbon canister controlled, no soak emissions are
estimated for this vehicle type. Average maximum and minimum tempera-