The effect of different vibration amplitude and frequency
Fig. 4 shows the effect of vertical and level vibration on transient
response of PEMFC at 20 Hz frequency and 905 smL/min
air flow rate. It can be seen that the voltage no response lager
undershoot or overshoot under no vibration conditions, and it
takes about 20 s to reach a new steady-state condition.
Compared with the no vibration, the voltage are response
exhibits larger fluctuations and then it takes about 50e80 s to
reach a new steady-state condition under the vertical and
level vibration amplitude of 3 mm and 4 mm. This can be
explained that the time of the voltage reaches a new steadystate
mainly depends on water reasonable distribution in
gas diffusion layer and flow channel. When the load changes
from a low to a high level, the cathode gas diffusion layer
generates large amounts of water, the vibration causes water
fluctuations and the uneven distribution in the gas diffusion
layer, which lead to the voltage fluctuation. Furthermore, it is
show that the steady-state voltage under the vibration is
higher than without vibration.
Fig. 5 shows an enlarged view of Fig. 4, it is found that, after
a load change, the voltage response under vibration exhibit
the lager under-shoot and over-shoot until it reaches a new
stead state. The under-shoot is the voltage decreases continuously
until it reaches the minimum level, this course takes
about 1e5 s. The over-shoot is the voltage increase