BACKGROUND

1. Technical Field

The present disclosure relates to a fuel cell system.

2. Description of the Related Art

In one previously proposed fuel cell system that uses pure hydrogen as a fuel gas, the fuel gas (anode off-gas) not used for electric power generation is returned back to the anode of the fuel cell and reused. However, in this fuel cell, for example, a phenomenon occurs in which part of nitrogen in air supplied to the cathode migrates to the anode side through an electrolyte. In this case, when the electric power generation of the fuel cell is continued, the concentration of nitrogen in the fuel gas increases gradually, so that the electric power generation efficiency of the fuel cell decreases.

For example, one method proposed to prevent the reduction in the electric power generation efficiency of the fuel cell as described above includes a purge operation in which impurities such as nitrogen in the anode off-gas are discharged to the outside. In this purge operation, since flammable hydrogen gas, as well as nitrogen, is present in the anode off-gas, it is necessary that the anode off-gas be diluted to a desired hydrogen gas concentration and then discharged to the atmosphere.

Japanese Unexamined Patent Application Publication No. 2008-235205 discloses a fuel cell system including: a heating medium circulation path through which a heating medium that recovers the heat of the fuel cell passes; a radiator (heat exchanger) in which heat is exchanged between the heating medium and air; and a fan that blows air into the heat exchanger. In this system, air having passed through the heat exchanger is used to dilute purge gas during the purge operation.

SUMMARY

In the conventional example, however, no studies were conducted on an air shortage problem that occurs when the anode off-gas is diluted with air in the purge operation.

One non-limiting and exemplary embodiment provides a fuel cell system in which, in the purge operation for discharging impurities in the anode off-gas to the outside, the amount of air used to dilute the anode off-gas can be maintained more appropriately than in the conventional example.

In one general aspect, the techniques disclosed here feature a fuel cell system including: a fuel cell that generates and outputs electric power using a fuel gas supplied to an anode and an oxidant gas supplied to a cathode; an anode off-gas discharge path through which an anode off-gas exhausted from the anode of the fuel cell is discharged; an electric power converter that converts the electric power output from the fuel cell; a case that houses the electric power converter; a first air feeder that supplies air to the case; a housing that houses the fuel cell, the case, and the first air feeder; and an air discharge path through which the air having passed through the case is discharged to outside of the housing, wherein a downstream end of the anode off-gas discharge path is connected to the air discharge path.

The fuel cell system in the above aspect of the present disclosure has the effect that the amount of air used to dilute the anode off-gas during the purge operation for discharging impurities in the anode off-gas to the outside can be maintained more appropriately than in the conventional example.

Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. The benefits and/or advantages may be individually obtained by the various embodiments and features of the specification and drawings, which need not all be provided in order to obtain one or more of such benefits and/or advantages.

