摘要 |
When an operation of a fuel cell system ( 100 ) is stopped, a flow of cathode off-gas into a circulation passage ( 28 ) is stopped. A stopped state of the flow of the cathode off-gas into the circulation passage ( 28 ) is held even after a start-up of the system ( 100 ) until the fuel cell ( 10 ) is brought into a predetermined state. Such structure prevents an outlet ( 52 ) of a three-way valve ( 50 ) from being frozen in an opened state. Accordingly the cathode off-gas that contains large amount of water and nitrogen hardly flows into the fuel cell ( 10 ) accidentally. This makes it possible to restrain various types of trouble, for example, generation of flooding upon start-up of the system, decrease in the oxygen partial pressure, and decrease in the power generation efficiency resulting therefrom.
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