Experimental

(l)Influence of air flow speed through the air channel on the cell performance

The relationship- between cell performance and air flow speed through the air channel of the separator was examined by 200cm2 single cells. Fabrication method of the test cell units was previously described Four kinds of the gas separators, in which the air channels were designed so that air flow speed became 1,3, 5,7 times that of separator adopted in 1 kW class module (1st model), were designed for the test cells.

©Effect of Teflon® amount on the carbon backing paper on the cell performance

The relationship between cell performance and Teflon® amount on the carbon backing paper was examined. Property of the backing carbon paper and cell performance were measured when the Teflon® amount on the backing carbon paper was changed. 25 cm2 single cells were used to measure the cell performance.

(3)Module operating test

The specification of 200 cm2 x 20 cell module (2nd model) and 200 cm2 x 36-cell module were listed in table 1. Photograph of 200 cm2 x 36-cell module is shown in figure 1. Water cooling was adopted and the cooling plate was placed in every two cells. Platinum amount of the cathode and the anode were controlled to 0.6 mg/cm2 and 0.5mg/cm2. Nafion® 115 was adopted as a membrane of the cell unit. Cell components were modified in both modules from the results of above experiment

These modules were tested using pure hydrogen as a fuel and air as an oxidant The output characteristics and the influence of reactant gas utilization on the module performance were measured. These results were compared with that of 200 cm2 x 20-cell module (1st model).

Table 1 Specifications of the test modules

Module

200cm2.20-cells(2nd model)

200cm2,36-celIs

Output power Cooling method

1 kW class Water cooling

2 kW class Water cooling

Relative air flow speed through air channel

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