Enlargement Of The Effective Surface Area

In order to enlarge the effective surface area, new M&E fabrication technologies named " the three dimensional bonding methodlII"( micro curved cell) and "waved electrode-membrane asscinbly[2]" (macro curvcd cell) were developed.

(1) Micro curved cell The schematics and effects of the bonding method are shown in Fig. 1 and 2 respectively. By enlarging the area of the catalyst layer and closing both electrodes, the performance of a micro curvcd cell is made superior to that of a non-bonded one (only contacting). ■

(2) Macro curvcd cell The schcmatics and effects of waved M&E are shown in Fig. 3 and 4 respectively. The "cell voltages of waved M&E are higher than that of flat M&E when oxygen is used, or in a low current density region. It was clear that gas diffusion problems arose, especially at the cathode, when the pitch of the wave was long.

START UP AND DSS CYCLE TEST OF A lkW CLASS MODULE WITH INT. HUM.

Fig. 5 shows the starting characteristics of a lkW class module with an internal humidifier (25-cclI stack). Full power was obtained within several tens of seconds of starting at room temperature. The power level of the module was stable even when the temperatures changed. An endurance test under the DSS (Daily Start and Stop) mode was also carried out and the results are shown in Fig. 6. Rather stable performance was maintained during over 50 DSS cycles.

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