Environmental Engineering Reference
In-Depth Information
radius and is typically 0.95-0.99. For the given passenger vehicle tyre, the static
rolling radius determined from (11.2) when
c
r
¼
1.0 is 367 mm.
For the sports utility test vehicle, a 2002 Ford Motor Co. Escape 4
4, the
frontal area and dynamic rolling radius predicted from (11.1) come out to
A
¼
0
:
9
ð
1
:
551
Þð
1
:
774
Þ¼
2
:
476
(m
2
,m)
ð
11
:
3
Þ
100
r
w
¼
ð
43
:
9
Þ
¼
0
:
363
2
p
The value for dynamic rolling radius calculated from (11.3) is 99% of the value
calculated from the tyre code when the coefficient is set equal to unity. This means
a value of
c
r
¼
0.99 will adjust the static rolling radius to dynamic rolling radius
with a good accuracy.
Atmospheric conditions of temperature (
C) and barometric pressure (in-Hg)
are used to correct the sea level air density to that of the testing location according
to (11.4):
288
:
16
273
:
16
þ
T
amb
P
r
29
:
92
r
¼
r
STP
(kg
=
m
3
)
ð
11
:
4
Þ
r
STP
¼
1
:
225
where air density at standard temperature and pressure (STP) is given for a bar-
ometer of 29.92 in-Hg (101.325 bar) and temperature of 15
C.
Example 1:
Using the results so far, verify the vehicle parameters for a small BEV
sports sedan and an electric scooter. The vehicles are shown here for reference;
both are EVs.
Mazda Miata and BSA Street Rider Scooter
Miata vehicle data
Parameter
Description Rating
Parameter
Description
Rating
Battery pack
44S
1P
200 Ah
lithium-ion
144 V,
28 kWh
Aerodynamic
C
d
(#)
0.25
Battery mass Kg
303.6
Rolling resistance
R
0
(kg/kg)
0.008
Vehicle mass Kg
920 (1,127) Rolling radius
P205/50R16V (
r
w
) 0.4m
A
f
(m
2
)
ICE power
kW
125
Frontal area
1.96
