JP2002358987A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system in which improvement in efficiency of fuel consumption and improvement in stability of fuel cell operation are made by reducing the supply quantity of humidifying water and increasing the circulation ratio of an ejector (circulation quantity/new supply quantity). SOLUTION: A high pressure fuel gas which is supplied from a hydrogen container 1 is supplied to the ejector 3 as a drive flow after regulated in pressure and flow rate by a pressure regulating valve 2. The humidifier 4 humidifies the fuel gas supplied to the fuel cell body 5. The exhaust gas discharged from the fuel pole outlet of the fuel cell body 5 is dehumidified by a dehumidifier 6 provided at the circulating passage 7 and re-circulated to the suction port of the ejector 3. Since the exhaust gas is dehumidified, the circulation ratio is improved. The water collected at the dehumidifier 6 is supplied to the humidifier 4 through a collection water passage 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel cell system, and more particularly to a fuel cell system for improving the balance of humidifying water suitable for use in vehicles.

[0002]

2. Description of the Related Art As a method of circulating fuel gas in the following fuel cell system, there is a fuel cell power generator disclosed in Japanese Patent Application Laid-Open No. 8-321316. According to this technology, a steam-water separator (dehumidifying means) is installed in a flue gas circulation path from a fuel electrode outlet to an ejector for the purpose of preventing water clogging due to water condensation in an ejector or a fuel gas supply path. Is condensed and removed.

[0003] In each path between the ejector and the fuel cell,
A heating device and heat exchanger are installed to maintain the temperature so that the water vapor in the passage does not condense.

[0004]

However, the conventional fuel cell power generator has the following problems. The steam separator provided in the exhaust gas circulation path
Although the steam in the exhaust gas is condensed by cooling the exhaust gas using the cooling water, the exhaust gas recirculated may be hotter than the new fuel gas supplied to the ejector. As for the performance of the ejector, when the inlet temperature of the driving flow is lower than the exhaust gas temperature returned by the exhaust gas circulation path, the ejector circulation performance as the circulation ratio (circulation amount / new supply amount) is reduced.

In a fuel cell system applied to a vehicle, water balance is an important factor, and water condensed by a steam separator in an exhaust gas circulation path is drained.
If the water in the system decreases and you drive for a long time,
Water supply will be required. In view of the above problems, an object of the present invention is to provide a fuel cell system that efficiently secures and supplies humidifying water.

It is another object of the present invention to provide a fuel cell system capable of easily obtaining a desired fuel gas flow rate and pressure by improving ejector circulation performance, and operating stably while improving an output range. .

[0007]

According to the first aspect of the present invention,
In order to achieve the above object, an ejector that circulates exhaust gas containing unreacted fuel gas discharged from a fuel cell body and uses the new fuel gas supplied to the fuel cell body as a driving flow and mixes the new fuel gas and the exhaust gas And a humidifier that humidifies the oxidizing gas or the fuel gas mixed with the ejector or both gases and supplies the humidified gas to the fuel cell body, and an exhaust gas circulation path that connects the exhaust gas outlet of the fuel cell body and the ejector. A dehumidifier for dehumidifying the exhaust gas,
In the fuel cell system provided with, the gist is to supply the water collected by the dehumidifier to the humidifier.

According to a second aspect of the present invention, in order to achieve the above object, in the fuel cell system according to the first aspect, the temperature of the exhaust gas recirculated to the ejector is changed to the temperature of the new fuel gas supplied to the ejector. The gist of the present invention is to provide a temperature adjusting means for bringing the temperature of the new fuel gas closer to the ejector or making the temperature of the new fuel gas close to or higher than the exhaust gas temperature.

According to a third aspect of the present invention, in the fuel cell system according to the second aspect of the present invention, the temperature adjusting means has a function of the dehumidifier and a new fuel gas supply passage of the ejector. The heat exchanger performs heat exchange between the heat exchanger and the exhaust gas circulation path.

According to a fourth aspect of the present invention, in order to achieve the above object, in the fuel cell system according to the second aspect, the temperature adjusting means is a heater installed in a new fuel gas supply path of an ejector. And

According to a fifth aspect of the present invention, in order to achieve the above object, in the fuel cell system according to the second aspect of the present invention, the temperature control means includes a heat source provided between a new fuel gas supply passage of an ejector and the humidifier. The point is to exchange.

According to a sixth aspect of the present invention, in order to achieve the above object, in the fuel cell system according to the first aspect, two humidity regulators disposed between the fuel cell main body and the ejector are provided. When the humidity controller is connected between the ejector outlet and the fuel gas inlet of the fuel cell body, the other humidity controller is connected between the exhaust gas outlet of the fuel cell body and the ejector circulation path inlet. While the humidity controller of the above is operated as a humidifier, the other humidity controller is operated as a dehumidifier, and the connection between the two humidity controllers is switched as appropriate to switch the role of the humidifier and the dehumidifier. And that it is provided with.

According to a seventh aspect of the present invention, in order to achieve the above object, the fuel cell system according to the sixth aspect operates as a heating source supply path provided in each of the two humidity regulators and as a humidifier. Heating source supply switching means for supplying a heating source to the humidity controller to be used.

According to an eighth aspect of the present invention, in order to achieve the above object, in the fuel cell system according to the sixth or seventh aspect, a cooling source supply path provided in each of the two humidity regulators; A cooling source supply switching unit that supplies a cooling source to a humidity controller that operates as a dehumidifier.

[0015]

According to the first aspect of the present invention, the new fuel gas supplied to the fuel cell main body is used as a driving flow to circulate the exhaust gas containing the unreacted fuel gas discharged from the fuel cell main body, and the novel fuel gas is circulated. An ejector for mixing a gas and the exhaust gas, a humidifier for humidifying an oxidizing gas or a fuel gas or a mixture of both gases supplied to the ejector and supplying the humidified gas to a fuel cell body, an exhaust gas outlet of the fuel cell body and the ejector And a dehumidifier for dehumidifying the exhaust gas in an exhaust gas circulation path connecting the fuel cell system and the dehumidifier, so that the water collected by the dehumidifier is supplied to the humidifier. And the amount of pure water for humidification can be reduced.

According to the second aspect of the invention, in addition to the effect of the first aspect, the temperature of the exhaust gas recirculated to the ejector is made closer to the temperature of the new fuel gas supplied to the ejector, or , The temperature of the new fuel gas supplied to the ejector is brought close to or higher than the exhaust gas temperature by means of temperature adjusting means, thereby improving the performance of the circulation ratio (circulation amount / new supply amount) in the ejector, This has the effect of reducing the amount of emissions. In addition, there is also an effect of further stabilizing the operation of the fuel cell.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, the temperature adjusting means has a function of the dehumidifier and a new fuel gas supply path of the ejector and exhaust gas circulation. Since the heat exchanger exchanges heat with the road, the exhaust gas is cooled by the new fuel gas and the new fuel gas is heated by the exhaust gas, and the moisture in the exhaust gas is removed. There is an effect that the cooling water is not required and the configuration of the fuel cell system can be simplified.

According to the fourth aspect of the invention, in addition to the effect of the second aspect, the temperature adjusting means is a heater installed in a new fuel gas supply path of the ejector. There is an effect that the temperature of the fuel gas is raised to approach the temperature of the exhaust gas to improve the circulation ratio.

According to the fifth aspect of the invention, in addition to the effect of the second aspect, the temperature adjusting means exchanges heat between the new fuel gas supply path of the ejector and the humidifier. Thus, there is an effect that the temperature of the new fuel gas is increased without providing a heater to approach the temperature of the exhaust gas to improve the circulation ratio.

According to the invention of claim 6, in addition to the effect of the invention of claim 1, two humidity regulators disposed between the fuel cell body and the ejector, and one of the humidity regulators Is connected between the ejector outlet and the fuel gas inlet of the fuel cell body, the other humidity controller is connected between the exhaust gas outlet of the fuel cell body and the ejector circulation path inlet to adjust the humidity of one side. While the device is operated as a humidifier, the other humidity controller is operated as a dehumidifier, and a switching valve that switches the connection between the two humidity regulators and switches the roles of the humidifier and the dehumidifier, as appropriate. With this, one humidifier humidifies and consumes internal moisture, and the other humidifier dehumidifies to store moisture and then switches both humidity regulators. The water between the two humidity regulators is changed by switching valves. There is an effect that it is possible to eliminate the transfer.

According to the seventh aspect of the present invention, in addition to the effects of the sixth aspect of the present invention, a heating source supply path provided in each of the two humidity adjusters and a heating source supply path which operates as a humidifier are provided. The provision of the heating source supply switching means for supplying the heating source to the humidity controller has an effect that the humidification performance of the humidity controller is further improved.

According to the invention described in claim 8, in addition to the effects of the invention described in claim 6 or 7, the cooling source supply paths respectively provided in the two humidity regulators and the dehumidifier are provided. The provision of the cooling source supply switching means for supplying the cooling source to the operating humidity controller has the effect of further improving the dehumidifying performance of the humidity controller.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is a schematic configuration diagram showing a configuration of a first embodiment of a fuel cell system according to the present invention. In FIG. 1, the fuel cell system according to the first embodiment includes a hydrogen cylinder 1 filled with a fuel gas at a high pressure and a pressure regulation for adjusting the high-pressure fuel gas of the hydrogen cylinder 1 to a predetermined controllable pressure. The valve 2, the fuel gas regulated by the pressure regulating valve 2 as a driving flow, the ejector 3 which mixes the exhaust gas from the fuel cell main body 5 and supplies the mixed gas to the humidifier 4, and the reaction film of the fuel cell main body 5 A humidifier 4 for humidifying the fuel gas in order to keep it in a wet state, a fuel gas main body 5 for supplying a fuel gas and air as an oxidizing gas and generating electricity by an electrochemical reaction thereof, and a fuel cell main body 5
A dehumidifier 6 disposed in a circulation path 7 extending from an exhaust gas outlet of the above to the suction port of the ejector 3 for condensing and removing water vapor from the exhaust gas in the circulation path 7, and humidifying the water generated by the dehumidifier 6 And a recovered water path 10 for supplying the collected water to the recovered water path 4.

Next, the operation and effect of this embodiment will be described. The circulation ratio r, which is a main performance index of the ejector 3
Is the ratio of the circulation flow rate Qr of the exhaust gas to the supply flow rate Qp of the new fuel gas supplied through the pressure regulating valve 2, that is, r
= Qr / Qp.

Here, the temperatures Top and Tos, the pressures Pop and Pos of the upstream part of the ejector and the inlet part of the circulation path, respectively,
From the densities ρop and ρos, ignoring the friction in the pipeline and formulating a continuous equation, equation of motion, and energy conservation equation, the circulation ratio r becomes the temperature ratio TR between the upstream of the ejector and the entrance of the circulation path. , Pressure ratio PR, density ratio ρR, TR and ρR
And proportional to the reciprocal of PR. If the proportionality constant is k, it is expressed by equation (1).

[0026]

R = Qr / Qp = k√ (TR) √ (ρR) / PR (1) where TR is Top / Tos and PR is Pop / Po.
s, ρR = ρop / ρos.

In the first embodiment, noting that ρR is improved, water vapor in exhaust gas from the fuel cell is condensed by the dehumidifier 6 to make PR closer to 1 and improve the circulation ratio r. I have.

Further, in the vehicle, since the pure water tank to be supplied to the humidifier 4 is desirably small, the water condensed by the dehumidifier 6 is collected by the humidifier 4 and other pure water through the recovery water path 10. Supply where needed.

[Second Embodiment] FIG. 2 is a schematic configuration diagram showing the configuration of a second embodiment of the fuel cell system according to the present invention. In the figure, in the fuel cell system of the second embodiment, a heat exchanger 8 for bringing a factor TR relating to the circulation ratio of the ejector 3 close to 1 is installed upstream of the ejector 3, and this heat exchanger 8 These also function as the dehumidifier 6 of FIG. The other configuration is the same as that of the first embodiment shown in FIG. 1, and the same reference numerals are given to the components having the same functions, and the duplicate description will be omitted.

In the present embodiment, the high-temperature exhaust gas from the fuel cell main body 5 is guided to the heat exchanger 8 via the circulation path 7 to exchange heat with the outer peripheral portion of the fuel gas supply path to the ejector 3. ing. Due to this heat exchange, the exhaust gas temperature Tos decreases, and the new fuel gas temperature Top increases.
Therefore, the temperature ratio TR = Top / Tos increases,
The circulation ratio r is improved.

Further, between the heat exchanger 8 and the humidifier 4, a recovered water path 10 for supplying condensed water to the humidifier 4 is provided. In the conventional example, cooling water for cooling the dehumidifier was required in order to condense the water vapor in the exhaust gas. However, in the second embodiment, the heat exchanger 8
Has the function of a dehumidifier, so there is no need to provide cooling water for dehumidification, and the configuration of the fuel cell system can be simplified.

[Third Embodiment] FIG. 3 is a schematic configuration diagram showing the configuration of a third embodiment of the fuel cell system according to the present invention. In the figure, the fuel cell system according to the third embodiment differs from the first embodiment shown in FIG. 1 in that a heater 9 is installed in a fuel gas path supplied to the ejector 3 and the temperature inside the heater 9 is changed. Thermometer in heater for detecting Th 2
1, a circulation path thermometer 22 for detecting the temperature Tr at the entrance of the circulation path of the ejector 3, and a control of the ON / OFF of the hot water or the flow rate of the hot water in the hot water path for supplying the hot water to the heater 9 for controlling the heater 9. And a hot water control valve 23. Other configurations are the same as those in FIG.

In the third embodiment, a heater 9 is provided in a fuel gas path supplied to the ejector 3, and the temperature Top (≒ Th) of the fuel gas supplied to the ejector 3 is returned from the circulation path 7 to the ejector 3. Circulating exhaust gas temperature Tos (ＴT
By increasing the temperature ratio to the same value as or more than r), the ejector circulation performance is improved by increasing the temperature ratio TR.

In FIG. 3, the heater 9 is a heater for heating the fuel gas with hot water, but is not limited to this, and may be an electric heater for increasing the temperature by electricity. In this case, instead of the hot water control valve 23, the heating by the electric heater can be controlled by an ON / OFF switch or a semiconductor switch capable of changing the energization time ratio.

FIG. 4 is a flowchart for explaining the control operation in the third embodiment, which is configured as a subroutine called at regular intervals. here,
The hot water control valve 23 is a simple open / close valve. First, the thermometer 21 in the heater and the thermometer 22 in the circulation path are read, and the temperature Th in the heater and the temperature Tr in the circulation path are obtained (step S10). Next, it is determined whether the circulation path entrance temperature Tr is higher than the heater internal temperature Th (step S1).
2) If Tr is high, open the hot water control valve 23 (step S14) and proceed to step S16. Step S1
If Tr is not high in the determination of 2, the process proceeds to step S16.

In step S16, it is determined whether or not [Th-Tr] exceeds a predetermined value T1. [Th-T
r] exceeds the predetermined value T1, the hot water control valve 23
Is closed (step S18), and the process returns. If [Th-Tr] does not exceed the predetermined value T1 in the determination of step S16, the process returns without doing anything. If the hot water control valve 23 is a valve whose opening can be adjusted, step S14 is performed.
May be controlled to increase the opening, and to decrease the opening in step S18.

If the temperature of the hot water used for heating is about the same as that of the exhaust gas of the fuel cell, or about tens of degrees higher,
In particular, there is no need to control using a temperature sensor or the like.

[Fourth Embodiment] FIG. 5 is a schematic configuration diagram showing the configuration of a fourth embodiment of the fuel cell system according to the present invention. In the figure, the fuel cell system of the fourth embodiment is different from the first embodiment shown in FIG. 1 in that fuel gas is supplied from a hydrogen cylinder 1 to an ejector 3 via a pressure regulating valve 2. The point is that the passage 11 passes through the inside of the humidifier 4 and heat is exchanged between the fuel gas and the humidifier 4. Other configurations are the same as those in FIG.

In the fourth embodiment, the fuel gas path 11 to be supplied to the ejector is passed through the humidifier 4 between the ejector and the fuel cell main body 5 to raise the fuel gas temperature and bring TR close to 1. This improves the circulation performance of the ejector.

In the third embodiment, it is not necessary to install a heater, but it is difficult to increase the TR to 1 or more due to heat exchange by the humidifier 4, and the amount of improvement in the ejector circulation performance can be improved. It is inevitable that it will be lower than in the third embodiment.

[Fifth Embodiment] FIG. 6 is a schematic configuration diagram showing the configuration of a fifth embodiment of the fuel cell system according to the present invention. In the figure, a fuel cell system according to a fifth embodiment has a hydrogen cylinder 1 filled with a fuel gas at a high pressure, and a pressure regulation for adjusting the high-pressure fuel gas of the hydrogen cylinder 1 to a predetermined controllable pressure. A valve 2, an ejector 3 for mixing the exhaust gas from the fuel cell body 5 with the fuel gas regulated by the pressure regulating valve 2 as a driving flow, and a fuel gas and air as an oxidizing gas are supplied. A fuel cell main body 5 for generating power by an electrochemical reaction, and two humidity regulators 11 and 12 provided between the ejector 3 and the fuel cell main body 5
When one of the humidity controllers (12 in the state of FIG. 6) is connected between the outlet of the ejector 3 and the fuel gas inlet of the fuel cell body 5, the other humidity controller (12 in the state of FIG. 6) 1
1) is connected between the exhaust gas outlet of the fuel cell main body 5 and the inlet of the ejector circulation path, and while one humidity controller 12 is operated as a humidifier, the other humidity controller 11 is used as a dehumidifier. Switching valves 13 and 14 which are operated to switch the functions of the humidifier and the dehumidifier by switching the connections of the humidity controllers 11 and 12 as appropriate, and hot water for supplying hot water to the humidity controller 11 or 12. Source 17 and humidity controller 1
A chilled water source 18 for supplying chilled water to 1 or 12; switching valves 15 and 16 for supplying hot water to one of the humidity regulators 11 or 12 and chilled water to the other;
And a control device 20 for controlling the control units 4, 15, and 16.

In the fifth embodiment, the switching valve 1
In the case where one of the two humidity regulators 11 and 12 is heated by hot water to become a humidifier by switching between 5 and 16, the other is cooled by cold water and adsorbs (or condenses) water vapor from exhaust gas with high humidity. If one is a dehumidifier, the other is a humidifier.

A moisture adsorbent such as, for example, granular silica gel or a polymer adsorbent is held inside the humidity adjusters 11 and 12, so that it is possible to exchange the flowing gas and moisture.
That is, when a high humidity gas flows, the humidity controllers 11 and 12 take in water vapor from the gas, and when a low humidity gas flows, the humidity controllers 11 and 12 humidify the gas from the gas. It has become.

The fuel gas circulates from the ejector 3 through the route of the humidity controller 12 (humidifier), the fuel cell body 5, the humidity controller 11 (dehumidifier), and the ejector 3. Exhaust gas from the fuel cell body 5 enters the ejector 3 in a state where water vapor is adsorbed (or condensed) by the humidity controller 11 (dehumidifier) and dehumidified to some extent. As described above, since the gas dehumidified in the circulation path has a lower density ρ, ρR is higher and the ejector circulation performance is improved.

In this state, sufficient moisture is taken into the humidity controller 11, and after the moisture is released from the humidity controller 12, the switching valves 13 and 14 are switched to dehumidify the humidity controllers 11 and 12. The role of the humidifier / humidifier is exchanged, and the humidity controller 12 serving as a humidifier becomes a dehumidifier, and the humidity controller 11 serving as a dehumidifier becomes a humidifier. Similarly, ρR is increased and the ejector circulation performance is improved. At this time, the switching valves 15 and 16 for switching the hot water and cold water supply destinations are simultaneously switched. The timing of switching these switching valves 13, 14, 15, 16 may be an elapsed time, a fuel cell main body inlet, or a hygrometer provided at each humidity controller.

FIG. 7A is a flowchart for explaining the control operation in the fifth embodiment, in which the elapsed time is used as the switching timing of the switching valve. This process is configured as a subroutine called at regular intervals. The timer for measuring the elapsed time used in this embodiment is a normal clock timer that can be reset at an arbitrary timing while being generally reset when the fuel cell system is started.

First, the time t of the humidity adjustment timer is read (step S20). Next, it is determined whether or not t exceeds the determination time To (step S22), and if not, the process returns without doing anything. If it exceeds, the timer is reset (t ← 0) (step S24), the switching valves 13 and 14 for switching the path of the fuel gas are switched (step S26), and the switching valves 15 and 16 for switching the path of the hot water and the cold water. (Step S28), and
To return. Note that the determination time To may be a constant or a variable set according to the operating state of the fuel cell, the gas supply target, or the like.

FIG. 7B is a flow chart for explaining the control operation in the fifth embodiment, in which the humidity detected by a hygrometer provided at the inlet of the fuel cell main body is used as the switching timing of the switching valve. is there. This process is configured as a subroutine called at regular intervals.

First, the humidity Hin by a hygrometer provided at the entrance of the fuel cell main body is read (step S30). Next, it is determined whether the humidity Hin is lower than the set value C (step S32). If the humidity Hin is not lower than the set value C, the process returns without doing anything. If it is lower, the switching valves 13 and 14 for switching the path of the fuel gas are switched (step S34), and the switching valves 15 and 16 for switching the paths of the hot water and the cold water are switched (step S36), and the process returns. The set value C may be a constant or a variable set according to the operating state of the fuel cell or the gas supply target.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing a main part of a first embodiment of a fuel cell system according to the present invention.

FIG. 2 is a system configuration diagram showing a main part of a second embodiment of the fuel cell system according to the present invention.

FIG. 3 is a system configuration diagram showing a main part of a third embodiment of the fuel cell system according to the present invention.

FIG. 4 is a flowchart illustrating an operation of the third embodiment.

FIG. 5 is a system configuration diagram showing a main part of a fourth embodiment of the fuel cell system according to the present invention.

FIG. 6 is a system configuration diagram showing a main part of a fifth embodiment of the fuel cell system according to the present invention.

FIG. 7A is a flowchart illustrating the operation of the fifth embodiment, and shows an example in which the humidity controller is switched according to the elapsed time. (B) It is a flowchart explaining operation | movement of 5th Embodiment, and shows the example which switches a humidity adjuster by humidity detection.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 hydrogen cylinder 2 pressure regulating valve 3 ejector 4 humidifier 5 fuel cell body 6 dehumidifier 7 circulation path 10 recovered water path

Claims (8)

[Claims] An ejector that circulates exhaust gas containing unreacted fuel gas discharged from the fuel cell main body while using the new fuel gas supplied to the fuel cell main body as a driving flow, and mixes the new fuel gas and the exhaust gas; A humidifier that humidifies the oxidizing gas or the fuel gas mixed by the ejector or both gases and supplies the humidified gas to the fuel cell main body; A fuel cell system comprising: a dehumidifier for dehumidifying water; and supplying the water collected by the dehumidifier to the humidifier. 2. The temperature of the exhaust gas recirculated to the ejector approaches the temperature of the new fuel gas supplied to the ejector, or the temperature of the new fuel gas supplied to the ejector approaches the exhaust gas temperature, or 2. The fuel cell system according to claim 1, further comprising a temperature adjusting unit configured as described above. 3. The heat exchanger according to claim 2, wherein said temperature adjusting means is a heat exchanger which also functions as said dehumidifier and performs heat exchange between a new fuel gas supply passage of said ejector and an exhaust gas circulation passage. The fuel cell system as described. 4. The fuel cell system according to claim 2, wherein said temperature adjusting means is a heater installed in a new fuel gas supply path of an ejector. 5. The fuel cell system according to claim 2, wherein said temperature adjusting means performs heat exchange between a new fuel gas supply path of an ejector and said humidifier. 6. When two humidity adjusters are provided between the fuel cell main body and the ejector, and one of the humidity adjusters is connected between the ejector outlet and the fuel gas inlet of the fuel cell main body. While the other humidity controller is connected between the exhaust gas outlet of the fuel cell body and the ejector circulation path inlet, and one of the humidity controllers is operated as a humidifier, the other humidity controller is used as a dehumidifier. 2. The fuel cell system according to claim 1, further comprising: a switching valve that operates as a switch, and switches the connection between the two humidity regulators to switch the roles of the humidifier and the dehumidifier. 7. A heating source supply path provided in each of the two humidity controllers, and a heating source supply switching unit for supplying a heating source to a heating source supply path of a humidity controller that operates as a humidifier. The fuel cell system according to claim 6, comprising: 8. A cooling source supply path provided to each of the two humidity controllers, and a cooling source supply switching means for supplying a cooling source to a cooling source supply path of a humidity controller that operates as a dehumidifier. The fuel cell system according to claim 6, comprising: