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时间:2010-05-10 19:48来源:蓝天飞行翻译 作者:admin
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year (e.g., day, week, month, year) by adjusting the applicable number of trips or miles traveled.
As mentioned above, motor vehicle emissions vary based on local ambient conditions (e.g., CO
is high in colder weather). If the time period of interest includes both warm and cold weather
seasons, the emissions should be calculated for each season to obtain an accurate emissions
estimate. In addition, emissions must be calculated separately for different years of interest, since
emission indices change by year.
These procedures do not illustrate how to determine the emission indices, which are based on
multiple other inputs. See the MOBILE user’s guide (Reference 88) for more information on the
calculation of emission indices. Similar calculation methodologies are grouped together below,
although different emission indices are needed for each type of calculation.
G-8
ET = EI x D x T x CF
Equation G-2: Crankcase or Running Losses
Where: ET - total hydrocarbon emissions, in pounds, resulting from crankcase or running
losses of the vehicle of interest in the given time period
EI - emission index, in grams per mile
D - distance traveled, in miles
T - number of vehicle trips
CF - 0.00220446 unit conversion factor from grams to pounds
ET = EIG x G x CF
or
ET = EID x D x T x CF
Equation G-3: Refueling Losses
Where: ET - total hydrocarbon emissions, in pounds, resulting from refueling losses of
the vehicles of interest in the given time period
EIG - emission index, in grams per gallon of fuel dispensed
EID - emission index, in grams per mile
G - gallons of fuel dispensed (that are used for airport access)
D - distance traveled, in miles
T - number of vehicle trips
CF - 0.00220446 unit conversion factor from grams to pounds
ET = EI x T x CF
Equation G-4: Hot Soak
Where: ET - total hydrocarbon emissions, in pounds, resulting from hot soak of the
vehicles of interest in the given time period
EI - emission index, in grams per trip
T - number of vehicle trips for which a soak period exists (i.e., vehicle trips with
a stop, such as in a parking lot)
CF - 0.0022046 unit conversion factor from grams to pounds
ET = EI x N x T x CF
Equation G-5: Diurnal (Partial/Full-Day or Multiple-Day of Rest)
Where: ET - total hydrocarbon emissions, in pounds, resulting from diurnal losses of the
vehicles of interest in the given time period
EI - emission index, in grams per vehicle day
N - number of days of rest (for partial/full-day calculations, number of days
equals 1)
T - number of vehicle trips (i.e., vehicles) for which a diurnal loss period exists
(i.e., vehicle trips with a stop, such as in a parking lot)
CF - 0.0022046 unit conversion factor from grams to pounds
G-9
ET = EIR x R x H x T x CF
or
ET = EID x D x T x CF
Equation G-6: Resting Losses
Where: ET - total hydrocarbon emissions, in pounds, resulting from resting losses of the
vehicles of interest in the given time period
EIR - emission index, in grams per hour of rest
EID - emission index, in grams per mile
R - days of rest
H - hours of rest per day to convert units from day to hours (assumed to be 24
hours/day)
D - distance traveled, in miles
T - number of vehicle trips for which a resting period exists (i.e., vehicle trips
with a stop, such as in a parking lot)
CF - 0.0022046 unit conversion factor from grams to pounds
G1.1.3 Idling Emissions
Idling emissions are calculated for vehicles with an extended idle time. Only extended idle times
are considered, since a normal amount of idle time already is incorporated into the exhaust
emission indices. The types of GAV that may have extended idle times at airports are passenger
vehicles and taxicabs. At air bases, GAV that may have extended idle times are base
transportation vehicles, such as buses or vans. Although the methodology and inputs are
generally the same for calculating idling emissions as for exhaust emissions, there are a few
minor modifications. These modifications are discussed in EPA’s MOBILE5 Information Sheet
#2: Estimating Idle Emission Factors Using MOBILE5 (Reference 75).
G1.1.4 Activity Categories
As mentioned in the above methodology, when calculating emissions from GAVs, vehicle
activity is divided into two categories: roadway and parking lot. The EPA procedures described
above are applied to both roadway and parking lot activity. Important issues and considerations
when applying the above procedures to roadways and parking lots are discussed below.
G1.1.4.1 Roadways
The above methodologies are used to determine GAV emissions from all vehicle roadway trips.
 
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