JP2013069536A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system that ensures stability and reduces purge frequency in low-load power generation and that favorably prevents drying in high-load power generation.SOLUTION: A fuel cell system 10 comprises: a fuel cell stack 12 that has a plurality of laminated fuel cells 20; an oxidant gas supply device 14; a fuel gas supply device 16; a first humidifier 54 that passes moisture between an air supply passage 52 and a fuel off gas passage 72; a second humidifier 62 that passes moisture between the air supply passage 52 and an oxidant off gas passage 60; and a controller 18 that exercises such control as to humidify the oxidant gas by means of only the first humidifier 54 when load on the fuel cell stack 12 is equal to or below a predetermined value.

Description

  The present invention provides a fuel cell having an electrolyte membrane / electrode structure in which a cathode electrode and an anode electrode are provided on both sides of an electrolyte membrane, an oxidant gas supply device for supplying an oxidant gas to the fuel cell, and the fuel cell. The present invention relates to a fuel cell system including a fuel gas supply device that supplies fuel gas.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) provided with an anode electrode and a cathode electrode on both sides of an electrolyte membrane made of a polymer ion exchange membrane is sandwiched between a pair of separators. Yes. A fuel gas passage for supplying fuel gas to the anode electrode is formed between one separator and the electrolyte membrane / electrode structure, and between the other separator and the electrolyte membrane / electrode structure. Is formed with an oxidant gas flow path for supplying an oxidant gas to the cathode electrode.

  Usually, it is used as a fuel cell stack by stacking a plurality of fuel cells. The fuel cell stack is mounted on, for example, a fuel cell electric vehicle in addition to stationary, and constitutes an in-vehicle fuel cell system.

  In this type of fuel cell, it is necessary to keep the electrolyte membrane moisturized in order to ensure good ion conductivity by the electrolyte membrane. For this reason, a method is employed in which an oxidizing gas (for example, air) or a fuel gas (for example, hydrogen gas), which is a reactive gas, is humidified and supplied to the fuel cell.

  At this time, moisture for humidification may be liquefied without being absorbed by the electrolyte membrane and stay in the reaction gas flow path. Further, in the fuel cell, generated water is generated at the cathode electrode by a power generation reaction, and the generated water is back-diffused through the electrolyte membrane in the anode electrode. For this reason, moisture tends to condense and stay in the reaction gas flow path, and flooding due to condensed water may occur.

  In order to solve this type of problem, for example, a fuel circulation fuel cell system disclosed in Patent Document 1 is known. This patent document 1 discloses a fuel cell that generates power by being supplied with fuel and an oxidant, a fuel supply channel that supplies the fuel to the fuel cell, and a fuel off-flow that is discharged from the fuel cell. The present invention relates to a fuel circulation type fuel cell system including a circulation flow path that joins a path.

  This fuel circulation type fuel cell system moves moisture between the internal fluid of the circulation flow path and / or the fuel supply flow path after joining, and the oxidant or the oxidant off-gas discharged from the fuel cell. A water permeable membrane type humidity adjusting device having a humidifying function and a dehumidifying function that can humidify or dehumidify the internal fluid and adjust the humidity of the internal fluid as desired. The fuel supply channel is provided.

  As a result, the humidity of the fuel off-gas can be adjusted as desired without discharging the fuel from the circulation channel by the purge operation, and as a result, the humidity of the fuel supplied to the fuel cell can be adjusted as desired. become.

Japanese Patent No. 4028320

  By the way, during low-load power generation of the fuel cell, the amount of fuel gas consumed is reduced, so that the water produced by the power generation reaction is less than dry hydrogen (fuel gas) that is newly introduced into the gas circulation system on the anode side. The amount of water that passes through the electrolyte membrane and moves to the anode side increases. For this reason, the gas circulation system on the anode side is easily oversaturated, and the power generation performance may be reduced.

  On the other hand, at the time of high load power generation of the fuel cell, the amount of moisture on the anode side that moves to the cathode side due to electroosmosis increases and the amount of fuel gas supply increases, so it is newly introduced into the gas circulation system on the anode side Compared to dry hydrogen, the amount of water that moves to the anode side tends to decrease. Therefore, there is a problem that the vicinity of the gas inlet of the fuel cell becomes dry.

  The present invention provides a fuel cell system capable of ensuring stability during low-load power generation and reducing the frequency of purge in this type of fuel cell, and also effectively suppressing drying of the electrolyte membrane during high-load power generation. The purpose is to provide.

  The present invention relates to a fuel cell having an electrolyte membrane / electrode structure in which a cathode electrode and an anode electrode are provided on both sides of the electrolyte membrane, an oxidant gas supply path for supplying an oxidant gas to the fuel cell, and an oxidation from the fuel cell. An oxidant gas supply device for providing an oxidant offgas passage for discharging the oxidant offgas, a fuel gas supply passage for supplying fuel gas to the fuel cell, and a fuel gas supply device for providing a fuel offgas passage for discharging fuel offgas from the fuel cell And a fuel cell system.

  In this fuel cell system, a first humidifier that transfers moisture between the oxidant gas supply path and the fuel off-gas path, and a second humidifier that transfers moisture between the oxidant gas supply path and the oxidant off-gas path. A humidifier and a control unit that controls the oxidant gas to be humidified only by the first humidifier when the load of the fuel cell is equal to or less than a predetermined value.

  In this fuel cell system, the oxidant gas supply path has a bypass supply path that bypasses the first humidifier and passes through the second humidifier, and controls the flow rate of the oxidant gas that flows through the bypass supply path. It is preferable to provide a regulating valve to perform.

  In the present invention, when the fuel cell is subjected to low load power generation, the oxidant gas is humidified only by the first humidifier that transfers moisture between the oxidant gas supply path and the fuel off-gas path.

  Therefore, the fuel offgas discharged from the fuel cell to the fuel offgas passage can supply sufficient moisture to the dry air (oxidant gas) flowing through the oxidant gas supply passage. As a result, the gas circulation system on the anode side is not oversaturated and the power generation performance is not deteriorated, and the number of times of drainage due to the purge operation of the fuel off gas can be suppressed.

  On the other hand, when the fuel cell is subjected to high load power generation, the first humidifier and the second humidifier can be used in combination. Therefore, it is possible to satisfactorily prevent drying near the gas inlet due to an increase in the supply amounts of the fuel gas and the oxidant gas.

  Thereby, while ensuring the stability at the time of low load power generation and reducing the purge frequency, drying at the time of high load power generation can be satisfactorily suppressed.

1 is an explanatory diagram of a schematic configuration of a fuel cell system according to a first embodiment of the present invention. It is a principal part disassembled perspective view of the fuel cell which comprises the said fuel cell system. It is front explanatory drawing of the 2nd separator which comprises the said fuel cell. It is a schematic structure explanatory drawing of the fuel cell system concerning the 2nd Embodiment of this invention. It is a principal part disassembled perspective view of the fuel cell which comprises the said fuel cell system.

  As shown in FIG. 1, the fuel cell system 10 according to the first embodiment of the present invention constitutes an in-vehicle fuel cell system mounted on, for example, a fuel cell electric vehicle (not shown).

  The fuel cell system 10 includes a fuel cell stack 12, an oxidant gas supply device 14 for supplying an oxidant gas to the fuel cell stack 12, a fuel gas supply device 16 for supplying a fuel gas to the fuel cell stack 12, A coolant supply device (not shown) for supplying a coolant to the fuel cell stack 12 and a controller (control unit) 18 for controlling the entire fuel cell system 10 are provided.

  The fuel cell stack 12 is configured by stacking a plurality of fuel cells 20. In each fuel cell 20, the electrolyte membrane / electrode structure 22 is sandwiched between the first separator 24 and the second separator 26. The 1st separator 24 and the 2nd separator 26 are comprised by metal separators and carbon separators, such as a steel plate, a stainless steel plate, an aluminum plate, or a plating processing steel plate, for example.

  As shown in FIG. 2, one end edge of the fuel cell 20 in the direction of arrow C (horizontal direction in FIG. 2) communicates with each other in the direction of arrow A, which is the stacking direction, and contains an oxidant gas such as oxygen First oxidant gas inlet communication hole 28a1 for supplying gas, fuel gas, for example, first fuel gas outlet communication hole 30b1 for discharging a hydrogen-containing gas, second oxidation for supplying the oxidant gas The agent gas inlet communication hole 28a2 and the second fuel gas outlet communication hole 30b2 for discharging the fuel gas are arranged in the arrow B direction (vertical direction).

  The other end edge of the fuel cell 20 in the direction of arrow C communicates with each other in the direction of arrow A, a first fuel gas inlet communication hole 30a1 for supplying fuel gas, and a first for discharging oxidant gas. An oxidant gas outlet communication hole 28b1, a second fuel gas inlet communication hole 30a2 for supplying the fuel gas, and a second oxidant gas outlet communication hole 28b2 for discharging the oxidant gas are provided in the direction of arrow B. Arranged and provided.

  A first refrigerant body inlet communication hole 32a1 for supplying a refrigerant body to one end edge portion (upper edge portion) of the fuel cell 20 in the arrow B direction and communicating with each other in the arrow A direction, and the refrigerant body are discharged. First refrigerant body outlet communication holes 32b1 are arranged in the arrow C direction.

  The other end edge portion (lower end edge portion) of the fuel cell 20 in the direction of arrow B communicates with each other in the direction of arrow A, and includes the second refrigerant body inlet communication hole 32a2 for supplying the refrigerant body, and the refrigerant body. Second refrigerant body outlet communication holes 32b2 for discharging are arranged in the direction of arrow C.

  A surface 24a of the first separator 24 facing the electrolyte membrane / electrode structure 22 has a first oxidant gas flow path 34a communicating with the first oxidant gas inlet communication hole 28a1 and the first oxidant gas outlet communication hole 28b1. , And a second oxidant gas flow path 34b communicating with the second oxidant gas inlet communication hole 28a2 and the second oxidant gas outlet communication hole 28b2 is provided separately. The first oxidant gas flow path 34a and the second oxidant gas flow path 34b are each configured by a plurality of oxidant gas flow path grooves extending in the direction of arrow C.

  As shown in FIG. 3, the first fuel communicated with the first fuel gas inlet communication hole 30 a 1 and the first fuel gas outlet communication hole 30 b 1 on the surface 26 a of the second separator 26 facing the electrolyte membrane / electrode structure 22. The gas flow path 36a and the second fuel gas flow path 36b communicating with the second fuel gas inlet communication hole 30a2 and the second fuel gas outlet communication hole 30b2 are individually provided. The first fuel gas flow path 36a and the second fuel gas flow path 36b are each composed of a plurality of fuel gas flow path grooves extending in the direction of arrow C.

  The oxidant gas flow direction of the first oxidant gas flow channel 34a and the second oxidant gas flow channel 34b and the fuel gas flow direction of the first fuel gas flow channel 36a and the second fuel gas flow channel 36b are opposite to each other. It is configured in a direction, that is, in a counterflow.

  As shown in FIG. 2, between the surface 24b of the 1st separator 24 which comprises the mutually adjacent fuel cell 20, and the surface 26b of the 2nd separator 26, it is the 1st refrigerant body flow path 38a and the 2nd refrigerant body. The flow path 38b is provided individually. The first refrigerant body channel 38a communicates with the first refrigerant body inlet communication hole 32a1 and the first refrigerant body outlet communication hole 32b1, and the second refrigerant body channel 38b communicates with the second refrigerant body inlet communication hole 32a2. 2 It communicates with the refrigerant body outlet communication hole 32b2. The first refrigerant body flow path 38a and the second refrigerant body flow path 38b are each composed of a plurality of refrigerant body flow path grooves extending in the direction of arrow C.

  The first separator 24 and the second separator 26 are respectively provided with seal members 40 and 42 integrally or individually. The seal members 40 and 42 use, for example, a seal material such as EPDM, NBR, fluoro rubber, silicon rubber, fluorosilicon rubber, butyl rubber, natural rubber, styrene rubber, chloroplane, or acrylic rubber, a cushion material, or a packing material. To do.

  The electrolyte membrane / electrode structure 22 includes, for example, a solid polymer electrolyte membrane 44 in which a perfluorosulfonic acid thin film is impregnated with water, and a cathode electrode 46 and an anode electrode 48 sandwiching the solid polymer electrolyte membrane 44. Prepare.

  The cathode electrode 46 and the anode electrode 48 are formed by uniformly applying a gas diffusion layer made of carbon paper or the like and porous carbon particles carrying platinum alloy (or Ru) on the surface thereof. And an electrode catalyst layer to be formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 44.

  As shown in FIG. 1, the oxidant gas supply device 14 includes an air pump 50 that compresses and supplies air from the atmosphere, and the air pump 50 is disposed in an air supply path (oxidant gas supply path) 52. .

  As will be described later, the air supply path 52 is provided with a first humidifier 54 for exchanging moisture and heat between a supply oxidant gas and an exhaust fuel gas (hereinafter referred to as fuel off gas), and The air supply path 52 communicates with the first oxidant gas inlet communication hole 28a1 and the second oxidant gas inlet communication hole 28a2 of the fuel cell stack 12. As the first humidifier 54, for example, a hollow fiber membrane humidification module using an ion exchange membrane or a flat membrane humidification module using an ion exchange membrane is used. For this reason, it can prevent that fuel gas and oxidant gas permeate | transmit and mutually mix.

  The air supply path 52 is provided with a bypass supply path 56 that bypasses the first humidifier 54, and the bypass supply path 56 has a regulating valve that controls the flow rate of the oxidizing gas flowing through the bypass supply path 56. 58 is arranged.

  The oxidant gas supply device 14 includes an oxidant off-gas passage 60 that communicates with the first oxidant gas outlet communication hole 28b1 and the second oxidant gas outlet communication hole 28b2. A second humidifier 62 is disposed in the oxidant off-gas path 60, and a bypass supply path 56 is connected to the second humidifier 62. The second humidifier 62 is configured in the same manner as the first humidifier 54. For example, a hollow fiber membrane type humidification module using a porous membrane or a flat membrane type humidification module using an ion exchange membrane is used. The The second humidifier 62 delivers moisture between the air supply path 52 and the oxidant offgas path 60. A dilution box 64 is disposed in the oxidant off-gas passage 60 at a position downstream of the second humidifier 62.

The fuel gas supply device 16 includes a hydrogen tank (H ₂ tank) 66 that stores high-pressure hydrogen. The hydrogen tank 66 communicates with the first fuel gas inlet communication hole 30a1 and the second fuel gas inlet communication hole 30a2 of the fuel cell stack 12 via a hydrogen supply path (fuel gas supply path) 68. An ejector 70 is provided in the hydrogen supply path 68. The ejector 70 sucks off the fuel gas off gas and supplies it to the hydrogen supply path 68.

  The fuel off-gas passage 72 communicates with the first fuel gas outlet communication hole 30b1 and the second fuel gas outlet communication hole 30b2 of the fuel cell stack 12. A first humidifier 54 is disposed in the middle of the fuel off-gas passage 72 to transfer moisture between the air supply passage 52 and the fuel off-gas passage 72.

  The fuel off-gas passage 72 communicates with the suction port side of the ejector 70 to form a hydrogen circulation passage. A drain path 74 is connected to the fuel off-gas path 72, and the drain path 74 is connected to the dilution box 64 via a purge valve 76.

  The operation of the fuel cell system 10 configured as described above will be described below.

  First, when the fuel cell system 10 is activated by an ignition switch or the like of a fuel cell electric vehicle (not shown), power generation by the fuel cell stack 12 is started.

  During normal operation, as shown in FIG. 1, air is sent to the air supply path 52 via the air pump 50 constituting the oxidant gas supply device 14. The air is humidified through at least one of the first humidifier 54 and the second humidifier 62, and then the first oxidant gas inlet communication hole 28a1 and the second oxidant gas inlet communication hole 28a2 of the fuel cell stack 12. To be supplied.

  On the other hand, in the fuel gas supply device 16, hydrogen gas is supplied from the hydrogen tank 66 to the hydrogen supply path 68. The hydrogen gas is supplied through the hydrogen supply path 68 to the first fuel gas inlet communication hole 30a1 and the second fuel gas inlet communication hole 30a2 of the fuel cell stack 12.

  As shown in FIG. 2, the air is supplied from the first oxidant gas inlet communication hole 28a1 and the second oxidant gas inlet communication hole 28a2 to the first oxidant gas flow path 34a and the second oxidant gas of the first separator 24, respectively. It introduce | transduces into the agent gas flow path 34b. The air is supplied to the cathode electrode 46 constituting the electrolyte membrane / electrode structure 22 while moving in the arrow C direction.

  On the other hand, as shown in FIGS. 2 and 3, the hydrogen gas passes through the first fuel gas inlet communication hole 30a1 and the second fuel gas inlet communication hole 30a2, and the first fuel gas flow path 36a of the second separator 26, respectively. It is introduced into the second fuel gas channel 36b. The hydrogen gas is supplied to the anode electrode 48 constituting the electrolyte membrane / electrode structure 22 while moving in the direction of arrow C.

  Therefore, in the electrolyte membrane / electrode structure 22, the air supplied to the cathode electrode 46 and the hydrogen gas supplied to the anode electrode 48 are consumed by an electrochemical reaction in the electrode catalyst layer, and electricity is generated.

  The refrigerant supplied to the fuel cell stack 12 is introduced into the first refrigerant inlet communication hole 32a1 and the second refrigerant inlet communication hole 32a2. The refrigerant body is introduced into the first refrigerant body flow path 38a and the second refrigerant body flow path 38b between the first separator 24 and the second separator 26, and then flows in the direction of arrow C. The refrigerant body cools the electrolyte membrane / electrode structure 22, and then is discharged from the first refrigerant body outlet communication hole 32b1 and the second refrigerant body outlet communication hole 32b2.

  Next, the air that is supplied to the cathode electrode 46 and at least partly consumed is used as the oxidant off-gas in the direction of arrow A along the first oxidant gas outlet communication hole 28b1 and the second oxidant gas outlet communication hole 28b2. Discharged. On the other hand, the hydrogen gas that has been supplied to the anode electrode 48 and at least partially consumed is discharged as fuel offgas in the direction of arrow A along the first fuel gas outlet communication hole 30b1 and the second fuel gas outlet communication hole 30b2. The

  As shown in FIG. 1, the oxidant off-gas is discharged from the first oxidant gas outlet communication hole 28 b 1 and the second oxidant gas outlet communication hole 28 b 2 to the oxidant off-gas path 60. The oxidant off-gas is sent to the second humidifier 62 to humidify the newly supplied air and then discharged to the dilution box 64. The dilution box 64 is supplied with the fuel gas discharged from the fuel off-gas path 72 to the drain path 74, and the fuel gas is diluted with air and then discharged to the outside.

  The fuel off gas is sent to the first humidifier 54 through the fuel off gas passage 72 from the first fuel gas outlet communication hole 30b1 and the second fuel gas outlet communication hole 30b2. This fuel off gas circulates through the first humidifier 54 to humidify newly supplied air, and then is sucked into the ejector 70 and supplied again to the fuel cell stack 12 as fuel gas.

In this case, the controller 18 detects the current value of the fuel cell stack 12 after the load application is started. When it is determined that the detected current value is equal to or less than a predetermined current value (for example, 0.2 A / cm ² ), that is, when it is determined that the fuel cell stack 12 is low load power generation, adjustment is performed. Valve 58 is closed. For this reason, the new air supplied by the air pump 50 is supplied only to the first humidifier 54 and the supply to the second humidifier 62 is stopped.

  Therefore, the fuel offgas discharged from the fuel cell stack 12 to the fuel offgas passage 72 can supply sufficient moisture to the dry air (oxidant gas) flowing through the air supply passage 52. As a result, the gas circulation system on the anode side (system formed by the hydrogen supply path 68, the anode side in the fuel cell stack 12, the fuel off-gas path 72, etc.) is in a water supersaturated state and power generation performance decreases. There is no. In addition, since the water in the fuel off gas is well removed, the number of times of drainage due to the purge operation of the fuel off gas can be suppressed.

On the other hand, when the controller 18 determines that the detected current value exceeds a predetermined current value (for example, 0.2 A / cm ² ), that is, it is determined that the fuel cell stack 12 is high load power generation. Then, the regulating valve 58 is controlled to be opened. For this reason, the 1st humidifier 54 and the 2nd humidifier 62 can be used together, and the dryness of the gas inlet_port | entrance by the increase in the supply amount of fuel gas and the supply amount of oxidizing gas can be prevented favorably. It becomes possible.

Thereby, in the first embodiment, the stability of the low load power generation (for example, about 0.2 A / cm ² or less) is ensured and the purge frequency is reduced, and the solid polymer electrolyte membrane 44 is formed during the high load power generation. The effect that it can suppress favorably drying is acquired. Note that low load power generation includes when the vehicle is idling.

  Furthermore, the oxidant gas flow direction of the first oxidant gas flow path 34a and the second oxidant gas flow path 34b and the fuel gas flow direction of the first fuel gas flow path 36a and the second fuel gas flow path 36b are: It is configured to counter flow. For this reason, it becomes possible to make the water content of both surfaces of the electrolyte membrane / electrode structure 22 uniform by self-diffusion.

  Moreover, the oxidant gas flow path is divided into a first oxidant gas flow path 34a and a second oxidant gas flow path 34b, while the fuel gas flow path is divided into a first fuel gas flow path 36a and a second fuel. The gas channel 36b is divided. Accordingly, there is an advantage that the amount of moisture in the surface is further uniformed, the dew generation region is reduced, and the durability in the low humidification operation is improved. Note that the oxidizing gas channel is not limited to two divisions, and may be, for example, three divisions or more.

  FIG. 4 is a schematic configuration explanatory diagram of a fuel cell system 80 according to the second embodiment of the present invention. The fuel cell system 80 includes the fuel cell 82 and is configured in the same manner as the fuel cell system 10 according to the first embodiment. The same components are denoted by the same reference numerals, and details thereof are described. The detailed explanation is omitted.

  As shown in FIGS. 4 and 5, the fuel cell 82 includes an electrolyte membrane / electrode structure 84 sandwiched between a first separator 86 and a second separator 88. The 1st separator 86 and the 2nd separator 88 are comprised by the metal separator or the carbon separator.

  As shown in FIG. 5, one end edge of the fuel cell 82 in the direction of arrow C (horizontal direction in FIG. 5) communicates with each other in the direction of arrow A, which is the stacking direction, The cooling medium inlet communication holes 32a and the fuel gas outlet communication holes 30b are arranged in the arrow B direction (vertical direction).

  A fuel gas inlet communication hole 30a, a coolant outlet communication hole 32b, and an oxidant gas outlet communication hole 28b communicate with each other in the arrow A direction at the other edge of the fuel cell 82 in the arrow C direction. Are provided in an array.

  An oxidant gas flow path 34 communicating with the oxidant gas inlet communication hole 28a and the oxidant gas outlet communication hole 28b is provided on the surface 86a of the first separator 86 facing the electrolyte membrane / electrode structure 84.

  A fuel gas passage 36 communicating with the fuel gas inlet communication hole 30a and the fuel gas outlet communication hole 30b is provided on a surface 88a of the second separator 88 facing the electrolyte membrane / electrode structure 84.

  A cooling medium that connects the cooling medium inlet communication hole 32a and the cooling medium outlet communication hole 32b between the surface 86b of the first separator 86 and the surface 88b of the second separator 88 constituting the fuel cells 82 adjacent to each other. A flow path 38 is provided.

  In the second embodiment configured as described above, the stability of the low load power generation and the purging frequency can be reduced, and the drying during the high load power generation can be well suppressed. The same effect as in the embodiment can be obtained.

DESCRIPTION OF SYMBOLS 10,80 ... Fuel cell system 12 ... Fuel cell stack 14 ... Oxidant gas supply device 16 ... Fuel gas supply device 18 ... Controller 20, 82 ... Fuel cell 22, 84 ... Electrolyte membrane and electrode structure 24, 26, 86, 88 ... Separator 34, 34a, 34b ... Oxidant gas flow path 36, 36a, 36b ... Fuel gas flow path
38, 38a, 38b ... refrigerant passage 44 ... solid polymer electrolyte membrane 46 ... cathode electrode 48 ... anode electrode 50 ... air pump 52 ... air supply path 54, 62 ... humidifier 56 ... detour supply path 58 ... regulating valve 60 ... Oxidant off-gas passage 66 ... Hydrogen tank 68 ... Hydrogen supply passage 70 ... Ejector 72 ... Fuel off-gas passage

Claims (2)

A fuel cell having an electrolyte membrane / electrode structure in which a cathode electrode and an anode electrode are provided on both sides of the electrolyte membrane;
An oxidant gas supply device for providing an oxidant gas supply path for supplying an oxidant gas to the fuel cell and an oxidant offgas path for discharging the oxidant offgas from the fuel cell;
A fuel gas supply device for providing a fuel gas supply passage for supplying fuel gas to the fuel cell and a fuel offgas passage for discharging fuel offgas from the fuel cell;
A fuel cell system comprising:
A first humidifier that transfers moisture between the oxidant gas supply path and the fuel off-gas path;
A second humidifier that transfers moisture between the oxidant gas supply path and the oxidant offgas path;
A control unit for controlling the oxidant gas to be humidified only by the first humidifier when the load of the fuel cell is a predetermined value or less;
A fuel cell system comprising: 2. The fuel cell system according to claim 1, wherein the oxidant gas supply path includes a bypass supply path that bypasses the first humidifier and passes through the second humidifier.
A fuel cell system comprising an adjustment valve for controlling a flow rate of the oxidant gas flowing through the bypass supply path.

Images