JP2005183178A - Fuel battery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inside humidification type fuel cell system minimizing the volume of gas flowing out to a humidifying agent supply passage when supplying fuel gas without supplying the humidifying agent, and preventing the fuel gas with high concentration from being exhausted outside through the humidifying agent supply passage. <P>SOLUTION: Pure water shutting valves 34 shutting a pure water supply passage 31 are arranged at the front side and back side of a pure water supply passage 31 supplying pure water as a humidifying agent to pure water poles 16, 17 of the fuel cell 10. When supplying at least the fuel gas or hydrogen to the fuel cell 10 without supplying the pure water as a humidifying agent, the pure water supply passage 31 is shut by the pure water shutting valve 34, just like the case of performing carbon corrosion prevention control when starting. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system including a solid polymer fuel cell using a solid polymer membrane as an electrolyte, and more particularly to a technique for suppressing the concentration of fuel gas discharged to the outside.

  Fuel cell technology that enables clean exhaust and high energy efficiency is attracting attention as a countermeasure against environmental problems in recent years, particularly air pollution caused by automobile exhaust gas and global warming caused by carbon dioxide. A fuel cell is an energy conversion system that supplies fuel gas (for example, hydrogen) and air to an electrolyte / electrode catalyst complex, causes an electrochemical reaction, and converts chemical energy into electrical energy. Above all, a polymer electrolyte fuel cell using a polymer electrolyte membrane as an electrolyte is easy to downsize at a low cost and has a high output density, so it is expected to be used as a power source for mobile vehicles such as automobiles. Has been.

  By the way, in the polymer electrolyte fuel cell, the solid polymer membrane functions as an ion conductive electrolyte by saturated water content, and also has a function of separating hydrogen and oxygen. If the water content of the solid polymer membrane is insufficient, the ionic resistance becomes high, and hydrogen and oxygen are mixed to make it impossible to generate power as a fuel cell.

  On the other hand, when hydrogen ions separated at the fuel electrode by power generation pass through the electrolyte membrane, water also moves together, so the fuel electrode side tends to dry. In addition, when the amount of water vapor contained in the supplied hydrogen or air is small, the solid polymer membrane tends to dry near the respective reaction gas inlets.

  For this reason, solid polymer membranes in polymer electrolyte fuel cells need to be moisturized by supplying moisture from the outside, and a humidifier such as pure water is directly supplied into the fuel cell. In addition, an internal humidification fuel cell system that performs humidification is known (see, for example, Patent Document 1).

In the invention described in Patent Document 1, humidification is performed on the reverse osmosis membrane side through a composite membrane composed of a reverse osmosis membrane that selectively permeates only water and an osmosis vaporization membrane that evaporates water permeated into the membrane from the membrane surface. The reaction gas is humidified by supplying water to the pervaporation membrane side.
JP 2000-208156 A

  Incidentally, even in the internal humidifying fuel cell system as described above, the humidifying agent is not always supplied to the fuel cell. For example, as in the following (1) and (2) examples, the humidifying agent is not supplied. In some cases, fuel gas is supplied to the fuel cell.

  (1) In order to maintain the power generation performance of the fuel cell, it is necessary to avoid carbon corrosion of the electrolyte membrane. In order to avoid this carbon corrosion, the electric power is taken out while suppressing the voltage, and oxygen in the oxidizer electrode (cathode). When the voltage is not generated by consuming.

  (2) When power generation is started without supplying a humidifying agent at the time of starting below freezing point.

  Thus, in the case of supplying fuel gas without supplying a humidifier in the internal humidification type fuel cell system, there is a possibility that the fuel gas flows out to the humidifier supply path, via the humidifier supply path. High concentration fuel gas may be discharged to the outside.

  The present invention has been proposed in view of such a conventional situation, and in an internal humidification type fuel cell system, when fuel gas is supplied without supplying a humidifier, it flows into the humidifier supply path. An object of the present invention is to provide a fuel cell system capable of minimizing the flow rate of the fuel gas and preventing the high concentration fuel gas from being discharged to the outside through the humidifying agent supply path.

  The fuel cell system of the present invention includes a fuel cell, a fuel gas supply means, a humidifying agent supply path, a humidifying agent supply means, and a humidifying agent supply path blocking means. A fuel cell is configured by laminating a unit cell in which an electrolyte membrane is sandwiched between a fuel electrode and an oxidant electrode, and a humidifier channel for internally humidifying the electrolyte membrane. Fuel gas is supplied to the battery from the fuel gas supply means. Further, a humidifying agent supply path is connected to the fuel cell, and the humidifying agent is supplied from the humidifying agent supplying means provided in the humidifying agent supplying path to the humidifying agent passage of the fuel cell. In the fuel cell system of the present invention, when supplying at least the fuel gas to the fuel cell without supplying the humidifying agent, the humidifying agent supply path is cut off by the humidifying agent supply path blocking means.

  Thereby, even in the case of the examples (1) and (2), the fuel gas does not flow to the outside through the humidifying agent supply path.

  According to the fuel cell system of the present invention, when supplying at least the fuel gas without supplying the humidifying agent, the flow rate of the fuel gas discharged to the humidifying agent supplying path is minimized, and the humidifying agent supplying path is used. It is possible to prevent high concentration fuel gas from being discharged to the outside.

  Hereinafter, embodiments of a fuel cell system to which the present invention is applied will be described with reference to the drawings.

  FIG. 1 is a conceptual diagram showing the connection of the characteristic features of the present invention. The fuel cell system of the present invention is an internal humidification type fuel cell system in which humidification is performed by directly supplying a humidifier such as pure water into the fuel cell. As shown in FIG. 1, fuel gas is supplied to the fuel cell. Based on the operating state of the fuel gas supply unit 1 that performs the operation and the output of the operating state detection unit 2 that detects the operating state of the fuel cell system, the humidifying agent supplying unit 3 supplies the humidifying agent to the fuel cell, Based on the operating state of the fuel gas supply means 1 and the output of the operating state detection means 2, the humidifying agent supply path blocking means 4 blocks the humidifying agent supply path.

  FIG. 2 shows a more specific configuration of the fuel cell system to which the present invention is applied. In the fuel cell system of this example, the fuel cell 10 includes a fuel electrode (anode) 11 and an oxidant electrode (cathode) 12, an electrolyte membrane 13 sandwiched between the fuel electrode 11 and the oxidant electrode 12, It consists of pure water electrodes (humectant channels) 16 and 17 stacked on the fuel electrode 11 and the oxidant electrode 12 via separators 14 and 15, and a cooling water channel 19 stacked on the separator 18. ing. A solid polymer film is used as the electrolyte membrane 13 of the fuel cell 10, a porous plate is used as the separators 14 and 15, and a solid plate is used as the separator 18.

  Here, the hydrogen supply to the fuel electrode 11 is performed by a hydrogen supply system (fuel gas supply means) having a hydrogen tank 20 as a hydrogen supply source. That is, the high-pressure hydrogen supplied from the hydrogen tank 20 through the hydrogen tank main valve 21 is mechanically reduced to a predetermined pressure by the pressure reducing valve 22, and the hydrogen at the fuel electrode 11 of the fuel cell 10 by the hydrogen supply valve 23. The pressure is controlled to be a desired hydrogen pressure and supplied to the fuel cell 10.

  The hydrogen supply system is provided with a hydrogen circulation passage 24, an ejector 25, and a hydrogen circulation pump 26 in order to recirculate hydrogen that has not been consumed by the fuel electrode 11 of the fuel cell 10. Here, the hydrogen circulation pump 26 supplements a region where the ejector 25 does not operate.

  Further, a purge valve 27 is installed in the external exhaust part of the fuel electrode 11 of the fuel cell 10. The purge valve 27 plays the following role.

(1) Discharge nitrogen accumulated in the hydrogen system in order to ensure the hydrogen circulation function.

(2) In order to recover the cell voltage, the water clogged in the gas flow path is blown away.

(3) In order to prevent deterioration of the fuel cell 10, the gas in the hydrogen system is replaced with hydrogen while consuming the oxygen of the oxidant electrode 12 at startup, and the oxygen of the oxidant electrode 12 is consumed even when stopped. .

  A dilution blower 28 is installed at a downstream position of the purge valve 27, and the hydrogen discharged from the purge valve 27 is diluted with air so as to have a hydrogen concentration lower than the flammable concentration and discharged outside the vehicle.

  On the other hand, air is supplied to the oxidizer electrode 12 by an air supply system having a compressor 29 as an air supply source. That is, air taken in from the outside by driving the compressor 29 is pumped to the oxidant electrode 12 of the fuel cell 10. At this time, the air pressure of the oxidant electrode 12 of the fuel cell 10 is controlled by driving the air pressure regulating valve 30.

  Supply of pure water to the pure water electrodes 16 and 17 of the fuel cell 10 is performed by a humidifier supply means (pure water tank 32 and pure water pump 33) via a pure water supply path 31 which is a humidifier supply path. . The pure water supply path 31 includes a humidifier supply path blocking means for blocking the pure water supply path 31 before and after the fuel cell 10 on both the inlet side and the outlet side of the pure water electrodes 16 and 17 of the fuel cell 10. A certain pure water shut valve 34 is installed.

  In each supply system, the air pressure of the oxidant, the gas pressure of hydrogen as the fuel, and the pressure of pure water as the humidifier are set in consideration of the power generation efficiency and the water balance in the fuel cell 10, The pressure difference is controlled at a predetermined pressure so that the electrolyte membrane 13 and the separators 14 and 15 of the fuel cell 10 are not distorted.

  The cooling water is supplied to the cooling water passage 19 of the fuel cell 10 by the cooling water pump 36 through the cooling water circulation passage 35. The cooling water circulation channel 35 is provided with a three-way valve 37, which switches or diverts the cooling water channel between the radiator 38 direction and the radiator bypass direction. The radiator 38 is provided with a radiator fan 39, and cools the cooling water by allowing air to pass through the radiator 38. The temperature of the cooling water is adjusted by driving the three-way valve 37 and the radiator fan 39.

  In addition, a power manager 40 is connected to the fuel cell 10, and the power manager 40 extracts power from the fuel cell 10 and supplies the power to a load (not shown) such as a motor that drives the vehicle.

  Further, the fuel cell system of the present embodiment includes a controller 41, a voltage sensor 42 that detects the voltage of the fuel cell 10, a pressure sensor 43 that detects the pressure at the inlet of the fuel electrode 11 of the fuel cell 10, and pure water of the fuel cell 10. A pressure sensor 44 that detects the outlet pressure of the poles 16 and 17 and a temperature sensor 45 that detects the inlet temperature of the cooling water passage 19 of the fuel cell 10 are provided, respectively, and the controller 41 is based on the output from each sensor. 10 operation states are determined (operation state detection means), and the operation of each actuator in the fuel cell system is controlled to an optimum state in each of the start, power generation, and stop states accordingly.

  In the fuel cell system configured as described above, in the fuel cell 10, fuel gas (hydrogen gas) is supplied to the fuel electrode 11, and oxidant gas (air) is supplied to the oxidant electrode 12. Electrode reaction proceeds and electric power is generated.

Anode (fuel electrode): H ₂ → 2H ⁺ + 2e ⁻ (1)
Cathode (oxidant electrode): 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O (2)
Here, a reaction catalyst such as a platinum catalyst is applied and formed on the surface of the electrolyte membrane 13 of the fuel cell 10 using carbon as a carrier, whereby the fuel electrode 11 and the oxidant electrode 12 are formed. In such an electrolyte membrane 13 of the fuel cell 10, the fuel electrode 11 and the oxidant electrode 12 of the fuel cell 10 are as shown in FIG. When this occurs, there is a problem in that carbon and water on the electrolyte membrane 13 react with each other at the oxidizer electrode 12 to cause carbon corrosion and the electrolyte membrane 13 deteriorates. This phenomenon will be described in detail with reference to FIG.

When oxygen and hydrogen remain in the oxidant electrode 12 and the fuel electrode 11 of the fuel cell 10 at the time of stoppage and are left without being connected to a load, respectively, the supply of hydrogen to the fuel electrode 11 of the fuel cell 10 starts at the time of startup. When the fuel electrode 11 is in a state where hydrogen and oxygen are separated, the proton H ⁺ moves from the fuel electrode 11 to the oxidant electrode 12, and the moved H ⁺ reacts with oxygen in the oxidant electrode 12. As a result, water is generated. In this reaction, the electron e ⁻ is required, but since the load is not connected, the electron e ⁻ does not move through the load. Therefore, the water present in the oxidant electrode 12 reacts with the carbon on the electrolyte membrane 13, and the generated electron e ⁻ is used for the water generation reaction in the oxidant electrode 12. At this time, the carbon on the electrolyte membrane 13 is deprived and the electrolyte membrane 13 deteriorates. In the fuel electrode 11, mixed oxygen, H ⁺ moved from the oxidant electrode 12, and an electron e ⁻ generated by protonation of hydrogen react to generate water. Here, if the open-circuit voltage is high, the movement of the electrons e ⁻ is likely to occur, and these chemical reactions are promoted, and the carbon corrosion of the electrolyte membrane 13 becomes intense. The carbon corrosion of the electrolyte membrane 13 affects the IV characteristics of the fuel cell 10. For this reason, the voltage of the fuel cell 10 falls and the problem that a big generated electric power cannot be obtained arises.

  From the above, in order to maintain the power generation performance of the fuel cell 10, it is necessary to avoid carbon corrosion of the electrolyte membrane 13. Therefore, hydrogen and air are separated at the fuel electrode 11 of the fuel cell 10, and a high voltage is obtained. It is necessary to avoid the situation. For this purpose, first, while hydrogen and air are separated, electric power is taken out while suppressing the voltage, and oxygen in the oxidizer electrode 12 is consumed so that the voltage does not stand. Thereafter, by continuously supplying hydrogen, the fuel electrode 11 is replaced with hydrogen, and the state where the hydrogen and air in the fuel electrode 11 are separated is also eliminated, so that even when an electromotive voltage is generated in the subsequent normal power generation, The fuel cell 10 is not deteriorated.

  However, in the internal humidification type fuel cell system, when the fuel gas is supplied to the fuel cell 10 without supplying the humidifying agent, the humidifying agent supply path passes through the separators 14 and 15 made of porous plates. Since there is a possibility that the fuel gas flows out to 31, it is necessary to newly supply gas to the pure water supply path 31 to reduce the concentration of the fuel gas.

  Therefore, in the fuel cell system of the present embodiment, when supplying fuel gas without supplying a humidifier to the fuel cell 10, the pure water supply path 31 is shut off before and after the fuel cell 10 by the pure water shut valve 34. Then, the flow rate of hydrogen discharged to the pure water supply path 31 is minimized, and air used for power generation of the fuel cell 10 (air from the compressor 29) is supplied to the pure water tank 32 to reduce the fuel gas concentration. By lowering, the concentration of the fuel gas discharged to the outside can be reduced with a simple structure.

  FIG. 4 shows the state of operation of the fuel cell 10 when the present invention is not applied (hydrogen supply amount, pure water supply amount, carbon corrosion prevention control on / off, hydrogen concentration in the pure water supply path, and in the pure water tank) Hydrogen concentration).

  When performing the start-up operation to avoid the above-described carbon corrosion, the fuel gas (hydrogen) is controlled to a predetermined pressure (or flow rate), and at the same time, the hydrogen circulation device (the ejector 25 and the hydrogen circulation pump 26) is started, Pure water is not supplied to the pure water electrodes 16 and 17 of the fuel cell 10. As a result, hydrogen supplied to the fuel cell 10 may flow into the pure water electrode 16 through the separator 14 formed of a porous layer between the fuel electrode 11 and the pure water electrode 16. This gas flows out of the fuel cell 10 and is accumulated in the pure water tank 32 as a result through the pure water supply path 31. In this case, the hydrogen concentration can be lowered by supplying air from the compressor 29 into the pure water tank 32, but the compressor 29 is stopped while the carbon corrosion prevention control without supplying air to the fuel cell 10 is performed. As a result, air is not supplied into the pure water tank 32 and high concentration hydrogen may accumulate.

  FIG. 5 shows the operation of the fuel cell 10 in the fuel cell system of the present embodiment (hydrogen supply amount, pure water supply amount, carbon corrosion prevention control on / off, pure water shut valve open / close, pure water tank Air supply amount, hydrogen concentration in pure water supply path, and hydrogen concentration in pure water tank).

  As shown in FIG. 5, in the fuel cell system of the present embodiment, the pure water supply valve 31 is shut off before and after the fuel cell 10 by the pure water shut valve 34 while the carbon corrosion prevention control is being performed. The hydrogen gas that has flowed into the pure water electrode 16 side of the battery 10 can be prevented from flowing into the pure water supply path 31. In addition, after the carbon corrosion prevention control is finished, the pure water supply path 31 is blocked by the pure water shut valve 34 so that a small amount of hydrogen gas staying in the pure water electrode 16 of the fuel cell 10 is supplied with pure water. At this time, the compressor 29 is activated and the air from the compressor 29 can be supplied to the pure water tank 32, so that the hydrogen in the pure water tank 32 is diluted with air. Thus, the hydrogen concentration can be lowered and discharged to the outside.

  FIG. 6 shows a control flow when the fuel cell system of this embodiment is started.

  As shown in FIG. 6, when the fuel cell system of the present embodiment is started, first, the pure water shut valve 34 is closed in step S1, and then hydrogen supply to the fuel cell 10 by the hydrogen supply system is started in step S2. . At the same time, in order to determine the amount of air to be supplied to the pure water supply path 31 (pure water tank 32) after completing the carbon corrosion prevention control, the controller 41 releases the pure water shut valve 34 from the fuel cell 10 and releases the pure water. The estimation of the amount of hydrogen flowing out to the water supply path 31 is started (outflow fuel gas amount estimating means).

  Here, the amount of hydrogen flowing out from the fuel cell 10 to the pure water supply path 31 after the pure water shut valve 34 is opened is stored in the fuel cell 10 while the pure water supply path 31 is shut off by the pure water shut valve 34. The amount of hydrogen produced, the pressure difference between the hydrogen pressure and the internal pressure of the pure water supply path 31, and the water generated during the shut-off of the pure water supply path 31 become steam at the temperature of the fuel cell 10 at that time. Determined by the amount released. The amount of hydrogen stored in the fuel cell 10 during the shutoff of the pure water supply path 31 is determined by the fuel cell 10 from the amount of supplied hydrogen supplied from the hydrogen tank 20 to the fuel cell 10 as shown in FIG. This is obtained by subtracting the amount of reaction hydrogen used for power generation from the amount of exhausted hydrogen released to the outside through the purge valve 27.

  The amount of hydrogen supplied from the hydrogen tank 20 to the fuel cell 10 can be estimated from the hydrogen pressure at the inlet of the fuel cell 10 and the elapsed time, and the amount of reaction hydrogen used for power generation can be determined while the pure water supply path 31 is shut off. It can be estimated from the amount of electric power extracted from the fuel cell 10. Further, the amount of discharged hydrogen released to the outside can be estimated from the hydrogen pressure and the size (predetermined value) of the purge valve 27. Therefore, the estimated value of the amount of hydrogen flowing out from the fuel cell 10 to the pure water supply path 31 after the pure water shut valve 34 is opened is the controller 41 outputs to the output of the voltage sensor 42, the pressure sensors 43 and 44, the temperature sensor 45, and the like. Based on this, it can be obtained by performing a predetermined calculation process.

  An electromotive force is generated in the fuel cell 10 by starting the supply of hydrogen in step S2, and if the hydrogen supply is continued in the state as it is, the voltage of the fuel cell 10 is increased to promote the carbon corrosion reaction. Therefore, in step S3, the controller 41 determines the operating state of the fuel cell 10 from the total voltage of the fuel cell 10 and the like (operating state detecting means), and takes out current as an index to suppress the voltage rise. Start corrosion prevention control. In step S4, the total voltage of the fuel cell 10 or the like is used to determine whether a condition for ending the carbon corrosion prevention control is satisfied. If the condition is satisfied, the carbon corrosion prevention control is performed in step S5. Exit.

  Thereafter, in step S6, air is supplied from the compressor 29 to the pure water tank 32 in order to dilute the hydrogen flowing out from the fuel cell 10 to the pure water supply path 31 and flowing into the pure water tank 32. At this time, based on the estimated value of the amount of hydrogen flowing out to the pure water supply path 31 performed in step S2, a sufficient amount of air is supplied from the compressor 29 to reduce the concentration of this hydrogen. Thereafter, the pure water shut valve 34 is opened in step S7, and the block of the pure water supply path 31 is released.

  Thereafter, in order to shift to normal operation, the supply of pure water to the fuel cell 10 is started in step S8, and the process further proceeds to step S9, where power generation in the normal fuel cell 10 is started. Through the series of processes described above, the control at the time of startup in the fuel cell system of the present embodiment is completed.

  The pure water shut valve 34 that opens and closes in step S1 and step S7 may be provided in the pure water supply path 31 or in the vicinity of the inlet / outlet of the fuel cell 10. Further, if the pure water pump 33 as the pure water supply means is provided with a sealing property, the pure water shut valve 34 on the inlet side of the fuel cell 10 can be omitted. In any case, the amount of fuel gas flowing out from the fuel cell 10 to the pure water supply path 31 at startup can be minimized.

It is a conceptual diagram which shows the principal part structure of the fuel cell system which concerns on this invention. It is a figure which shows an example of the specific structure of the fuel cell system to which this invention is applied. It is a figure explaining carbon corrosion. The state of operation of the fuel cell when the present invention is not applied (hydrogen supply amount, pure water supply amount, carbon corrosion prevention control on / off, hydrogen concentration in the pure water supply path, and hydrogen concentration in the pure water tank) is shown. FIG. Operation of the fuel cell when the present invention is applied (hydrogen supply amount, pure water supply amount, carbon corrosion prevention control on / off, pure water shut valve open / close, pure water tank air supply amount, It is a figure which shows the hydrogen concentration in a pure water supply path | route, and the hydrogen concentration in a pure water tank. It is a flowchart which shows the control flow at the time of starting in the fuel cell system of this invention. It is a figure explaining the method of estimating the quantity of the hydrogen which flows into a pure water supply path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel gas supply means 2 Operation | movement state detection means 3 Humidifier supply means 4 Humidifier path | route interruption | blocking means 10 Fuel cell 11 Fuel electrode 12 Oxidant electrode 13 Electrolyte membrane 14, 15 Separator (porous plate)
16, 17 Pure water electrode 31 Pure water supply path 32 Pure water tank 33 Pure water pump 34 Pure water shut valve

Claims (7)

A fuel cell configured by laminating a unit cell in which an electrolyte membrane is sandwiched between a fuel electrode and an oxidizer electrode, and a humidifier channel for internally humidifying the electrolyte membrane;
Fuel gas supply means for supplying fuel gas to the fuel cell;
A humidifying agent supply path for supplying a humidifying agent to the humidifying agent flow path of the fuel cell;
A humidifying agent supply means provided in the humidifying agent supply path;
A humidifier supply path blocking means for blocking the humidifier supply path before and after the fuel cell;
A fuel cell system, wherein when the fuel gas is supplied to the fuel cell without supplying the humidifier, the humidifier supply path is shut off by the humidifier supply path cutoff means. Having an operating state detecting means for detecting an operating state of the fuel cell;
At the time of system startup, the humidifying agent supply path is cut off by the humidifying agent supply path blocking means while electric power is taken out from the fuel cell while supplying only the fuel gas based on the output from the operating state detecting means. The fuel cell system according to claim 1. The fuel gas flowing out to the humidifying agent supply path is mixed with an oxidant gas, and then discharged to the outside.
3. The humidifying agent supply path is shut off by the humidifying agent supply path blocking means while only the fuel gas is supplied to the fuel cell without supplying an oxidant gas. 4. Fuel cell system. An outflow fuel gas amount estimating means for estimating the amount of fuel gas flowing out to the humidifying agent supply path;
The oxidant gas amount mixed with the fuel gas is determined based on an estimation result of the outflow fuel gas amount estimation means, and the determined amount of oxidant gas is supplied to the humidifying material supply path. 4. The fuel cell system according to 3.   The spilled fuel gas amount estimation means includes a fuel gas amount stored in the fuel cell while the humidifier supply path is shut off, a differential pressure between the pressure of the fuel gas and the internal pressure of the humidifier supply path, and The amount of water generated during the shutoff of the humidifying agent supply path is released as water vapor at the temperature of the fuel cell, and after releasing the shutoff of the humidifying agent supply path by the humidifying agent supply path shutting means The fuel cell system according to claim 4, wherein the amount of fuel gas flowing out to the humidifying agent supply path is estimated.   2. The humidifying agent supply path blocking means is configured to block one of the front and rear of the fuel cell in the humidifying agent supply path with the humidifying agent supplying means and the other with a valve. 6. The fuel cell system according to any one of 5 above.   The fuel cell system according to any one of claims 1 to 6, wherein the fuel cell is formed by laminating the unit cell and the humidifying agent channel via a porous separator.

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