Environmental Engineering Reference
In-Depth Information
Fuel tank and conventional vehicle accessory battery (SLI) both represent mass
savings in the hybridized vehicle.
Gross vehicle weight is only slightly less for the hybrid vehicle.
The bottom line is that hybridizing a conventional vehicle can easily consume
all weight reduction actions taken before the hybrid components are installed.
Rather than retrofit and modify a conventional vehicle, it would be more
appropriate to design a hybrid vehicle (fuel cell vehicle for that matter) from the
ground up.
4.9 Exercises
Q1: Using the mid-sized vehicle data given in Table 4.1, the result of Example 1
and a simple calculation based on the equation in Example 1, show that the
ratio of vehicle peak accelerating power to cruise power is > 10:1.
A1:
11:1 for this particular set of parameters.
Q2:
For the duty cycle values calculated from the equation in Example 3,
determine what the converter output current, I d , and ultra-capacitor current,
I c , are when the battery voltage U d = 150 V and for
a. Motoring mode power of 12 kW.
b. Regenerating mode power of 6 kW.
A2:
(a) 162.3 A and (b) 78.9 A.
Q3: A plug-in hybrid electric vehicle is charged using Class II equipment sup-
plied from a 240 V ac line and delivers a constant 7 kW over a 12 AWG
cable. According to NEC 400.5(B) a 25 00 2 wire conducting cable is rated for
31 A rms and the load here is 30 A rms . If the charging equipment is located in
a residential garage and the cable is rated 60 C and well insulated (elec-
trically and thermally), then will the cable conductors remain below 60 Cin
a30 C ambient after charging for 8 h?
Hint: For copper conductors a 20 = 0.00427 K 1 , specific heat, c p = 385 kJ/kg-K,
12 AWG wire is 29.42 kg/km and 5.21 W /km. Use Q = Mc p d T for heat input.
A3: Yes, the near adiabatic heat input into the copper conductors of the cable is
well below the thermal capacity of the total cable mass.
Q4: A PHEV lithium ion pack of LFP chemistry is rated 15 kWh and is assumed to
have 42% of its total elemental lithium participate in energy storage. Using
the results of Example 4, calculate how much total lithium metal is needed in
this PHEV battery and what is relative equivalent lithium per kWh?
A4:
2,642 g (2.64 kg) and 176 g/kWh.
Q5:
Find the energy stored in (J) and (Wh) and calculate the following
metrics, SP, SE, PD and ED (specific P & E, and E & P density), given an
ultra-capacitor cell having C = 3,000 F, U mx = 2.7 V, M = 0.54 kg and
V ol = 0.475 dm 3 .
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