20 30 40 50 Air utilization (% ) Fig. 4 Relationship between module voltage and air utilization.

utilization of 50 %. It was confirmed that modification of the air channel design and change in the TeflonĀ® amount- of the backing carbon paper was effective to improve the module performance in a higher air utilization.

Figure 5 shows output characteristic of 200 cm2 x 36-cell module. The output power of 2.22 kW, power density of 0.31 W/cm2 was obtained at- a current density of 500 mA/cm2, a pressure of 3 atm and a air utilization of 40 %. Uniform cell voltage distribution of about 20 mV was observed

Figure 6 shows the result of daily start-shut-down operation test of 200 cm2 x 36-cell module. The test continued for a 3700 hours and about 40 cycles of operation was achieved The module voltage was almost constant at a current density of 300mA/cm2, but The cell resistance tended to increase slightly in this period

Fig. 5 Output characteristics of 200 cm2 x 36-cell module.
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