Page 150 - Introduction to Transfer Phenomena in PEM Fuel Cells

Heat Transfer Phenomena 139
Therefore, the results show irregular heat generation at the electrodes.
Ramousse et al. [RAM 09] suggested that it is due to the hydrogen oxidation
reaction being highly exothermic, while the oxygen reduction reaction is
endothermic.
There are few reviews in the literature on the topic of cooling channels in
PEM fuel cells. On the contrary, many studies are underway on the transport
of heat and water in this same type of fuel cell and for its different layers.
Chen et al. [CHE 03] numerically studied different types of cooling
methods (parallel and serpentine channels). They used a criterion known as
Index of Uniform Temperature (IUT). In their simulations, they used the
uniform heat flow generated by the stack.

At the inlet of the channel, they specified the mass flow and the flow
velocity values, but they did not mention anything for the channel outlet.

They assumed that the surrounding surface at the cooling plates is
adiabatic, and that the surrounding area along the edge of the flat plate is
small.

For the heat transfer from the solid structure to the fluid, the convective
heat transfer coefficient is estimated from a correlation taking into account
the conjugated heat transfer.

On conclusion of their work, they indeed found that cooling with
serpentine channels was better than parallel channels with consequent charge
loss.

Choi et al. [CHO 08] digitally analyzed the performance of the plate
cooling system in the PEM fuel cell. These studies are similar to those of
Chen et al. [CHE 03]. They studied the two types of panel configurations
(parallel and serpentine) using maximum surface temperature as an
optimization criterion. They also used a uniform heat flux for heat
generation and analyzed for three different values of heat flow, the case
where there is one, three and finally five cell units in a stack. From their
results, they concluded that the maximum surface temperature increases
linearly, the heat flux increases for their two particular designs with two
different Reynolds numbers.