Environmental Engineering Reference
In-Depth Information
with the stack power from 0.32 to about 2%, while the instantaneous values, not
reported in Table
6.2
, were not higher than 4%. In the same Table
6.5
, the stack
and FCS efficiencies are also reported, the values obtained indicate that in the
range of temperatures investigated in Fig.
6.28
the FCS efficiency is comprised
between 0.40 and 0.48, except for the conditions of low load, when auxiliary
components consume most of the produced electric energy [
3
].
6.5 Characterization of the Overall Power Train on Driving
Cycles
The aim of the experimental tests performed on the overall power train is the
evaluation of efficiency and the individuation of the basic energy management
strategies necessary to assure proper vehicle operation. The experimental inves-
tigation is performed in dynamic conditions on two different urban driving cycles,
the R47 and R40, considered by the European regulations on vehicle emission
control. In Fig.
6.21
a and b, the two cycles are reported in terms of motor speed
versus time.
In particular, the R47 cycle (Fig.
6.21
a) is imposed by European legislation for
exhaust emission measurements of mopeds powered by internal combustion
engine, and here is used in absence of specific legislation regarding electrical
mopeds. The R47 cycle requires the maximum power in the initial phase up to the
maximum speed (6000 rpm), then a period of constant speed of 50 s at maximum
speed, a fast deceleration up to 2400 rpm, a second period of constant speed, a
final deceleration up to zero speed. The R40 cycle (Fig.
6.21
b) comprises three
phases, the first two characterized by acceleration, constant speed (1500 and
3200 rpm) and deceleration steps, while the last one presents two steps at constant
speed (5000 and 3500 rpm), before returning to zero speed.
The R40 cycle is required by the European legislation to evaluate the exhaust
emissions of motorcycles and, after addition of a fourth phase at higher speed, also
for passenger cars. It is used in this chapter to evaluate the performance of the fuel
cell power train on a typical urban route, not strictly associated with the driving
way assumed for a moped. The acceleration phases of the two cycles correspond to
stack power increase rates of 100 W/s for R40 and 500 W/s for R47.
6.5.1 Analysis of the FCS Dynamic Behavior on Driving Cycles
In Fig.
6.22
a, b, the acquisition versus time of stack current, voltage, and tem-
perature is reported for one R40 and four consecutive R47 driving cycles,
respectively [
1
]. The purge, humidification, and stoichiometric ratio control
strategies described in the previous sections are used also during these tests.
