Supplied gaseous oxygen and gaseous hydrogen are warmed by the preheaters, and are fed to a cell stack through the pressure regulators. The oxygen line is a blind alley except for the purge line of accumulated impurity gas, that is, gaseous oxygen is supplied just as much as it is consumed. Gaseous hydrogen is circulated by a separator pump. Water vapor in gaseous hydrogen, the reaction product in the cell stack, is condensed in a condenser, and then condensed water is removed from gaseous hydrogen by the separator. In addition, the heat generated by the fuel cell reaction is carried away from the cell stack by circulating coolant, and then the cell stack is maintained at a constant temperature. FUNDAMENTAL TEST Test Procedure The fundamental study of the fuel cell system is carried out in two phases which are the fundamental test of the fuel cell and the functional test of the fuel cell system. The fundamental test of the fuel cell has been completed, and the functional test of the fuel cell system is in preparation. The fundamental test of the fuel cell was carried out successively as follows: Major Characteristics The power of the flight type fuel cell system is expected to range up to several kW. However, a power of 80 W was planned as the target power of the fuel cell of the test bed for developing the above fuel cell system of the space vehicle. The specification of this fuel cell is as follows: Construction of Fuel Cell The basic model of the experimental cell for the test bed is shown in Fig. 2. A cathode and an anode are gridless sheets of silver-palladium alloy rolled with polytetrafluoroethylene binder. The electrodes are separated by an asbestos matrix impregnated with a 30% electrolyte solution of potassium hydroxide. A current collector made of expanded nickel screen is placed in the gas chamber behind each electrode. A porous sintered nickel plate attached to the anode is designed to act as the electrolyte reservoir. Small perforation distributed over the electrolyte reservoir plate allows free access of gaseous hydrogen to the anode. The outside and exploded view of the 5 cell stack are shown in Fig. 3.
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