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Therefore, for the current cell design, excess water was used to control the temperature of
the cell and also to prevent the membrane electrode assembly from drying.
The experimental results were grouped together to clearly see the effect of excess
water flow on the voltage. These are shown in Figure 4.9 (a)-(c). Temperatures were 30 o C
in Figure 4.9(a), 40 o C in Figure 4.9(b) and 50 o C in Figure 4.9(c).
a b
c
Figure 4.9. (a)-(c) Excess Water Flow Effect on Electrolysis
At 500mAmp/cm 2 , oxygen flow rate from the cell was 37.5ml/min. At 1g/min water
flow rate, 2.5% (by volume) of the output stream coming from anode side was water (the
rest was oxygen) and at 10g/min, this fraction increased to 21%. Total liquid volumetric
flow rate from the cell increased 23% although oxygen generated was the same at a
constant current density. In addition, excess water did not result in adverse effect on the
voltage (at a constant current denisty). The main advantage of excess water is to control
the temperature of the cell. This is especially critical at high current densities. In other
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