Environmental Engineering Reference
In-Depth Information
Q3: Referring to Example 4 and Table 2.5 for the Camry Hybrid, the vehicle
propulsion power, P ( V ), stated here must match the road load. Determine
whether or not the vehicle's net propulsion power is sufficient to match the
road load at V WOT and if not, then to what speed can it match road load.
Assume level terrain, no headwind and no driveline losses. Also, (2.7) uses
M = M v + M pass and V WOT = 132.6 mph:
V 3
1
2 r air C d A f
P ð V Þ¼ MV V þð gC rr M Þ V þ
þð gM sin V
ð 2 : 7 Þ
A3:
For a single occupant at standard mass P (59.29) = 0 + 8,129.3 + 81,698.7 +
0 = 89.828 kW. The net propulsion power of the 2010 Camry Hybrid: P net =
P e + P b = 110 kW + 30 kW = 140 kW. So, yes, the propulsion power is
sufficient to sustain this speed under ideal conditions.
Q4: At what steady speed can the Camry Hybrid in Q3 sustain for the case of
four occupants, 20 mph headwind and 6% grade?
Hint: Convert the %grade to angle using (2.8) as we'll see in Chapter 3:
q ¼ tan 1 %grade
100
ð 2 : 8 Þ
A4:
Since the net available propulsion power is 140 kW, the maximum speed
can be stated as (2.9):
V 3
1
2 r air C d A f
P ð V Þ¼ P net ¼ 140 kW ¼½ gC rr M þ gM sin q V þ
ð 2 : 9 Þ
V 3
82 V 2
þ
26
:
þ
26,055
:
6 V
356,428
:
36
¼
0
Or, V = 13.57 m/s = 30.36 mph.
For these conditions the vehicle can sustain only 30 mph.
Q5: Much has been said of energy storage for hybrid vehicles and more will be
covered in later chapters. For this question, consider the power and energy
metrics of the regenerative energy storage system (RESS) pack for various
classes of hybrid vehicles listed in Table 2.8. For each class of vehicle,
Table 2.8 Approximate peak power and energy metrics by hybrid vehicle class
Class
Peak power
(kW)
Total stored
energy (kWh)
Power/energy
ratio ( P / E )
Open circuit
voltage
Mild hybrid
12
1
12
158
Strong
27
1.3
20
330
PHEV
130
16
8.12
330
BEV
136
42
3.3
335
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