WO2011158295A1 - 燃料電池 - Google Patents
燃料電池 Download PDFInfo
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- WO2011158295A1 WO2011158295A1 PCT/JP2010/004036 JP2010004036W WO2011158295A1 WO 2011158295 A1 WO2011158295 A1 WO 2011158295A1 JP 2010004036 W JP2010004036 W JP 2010004036W WO 2011158295 A1 WO2011158295 A1 WO 2011158295A1
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- fuel cell
- cathode
- catalyst layer
- water
- cooling
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
- H01M8/04029—Heat exchange using liquids
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0267—Collectors; Separators, e.g. bipolar separators; Interconnectors having heating or cooling means, e.g. heaters or coolant flow channels
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
- H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
- H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
- H01M8/04156—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying with product water removal
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
- H01M8/04225—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells during start-up
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
- H01M8/04253—Means for solving freezing problems
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04298—Processes for controlling fuel cells or fuel cell systems
- H01M8/043—Processes for controlling fuel cells or fuel cell systems applied during specific periods
- H01M8/04302—Processes for controlling fuel cells or fuel cell systems applied during specific periods applied during start-up
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/2465—Details of groupings of fuel cells
- H01M8/2483—Details of groupings of fuel cells characterised by internal manifolds
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M2008/1095—Fuel cells with polymeric electrolytes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Definitions
- the present invention relates to a fuel cell that generates power by an electrochemical reaction between hydrogen and oxygen, and more particularly to a technique for operating the fuel cell in a cold environment.
- a fuel cell As a fuel cell, a plurality of membrane electrode assemblies (hereinafter also referred to as “MEA”) in which electrode layers are bonded to both surfaces of an electrolyte membrane, and a separator that separates each of these membrane electrode assemblies are provided. Alternating layers are known.
- MEA membrane electrode assemblies
- Such a fuel cell separator has a flow path for flowing hydrogen gas to the anode side of the MEA, a flow path for flowing oxidizing gas to the cathode side of the MEA, and a flow path for flowing a cooling medium for cooling the fuel cell.
- generated water is generated on the cathode side of the MEA with the electrochemical reaction between hydrogen and oxygen. In a cold environment, the produced water generated in the MEA may freeze and cause the MEA to deteriorate significantly.
- Patent Document 1 when starting a fuel cell in a cold environment, there is a technique for preventing an excessive temperature drop of the fuel cell due to the cooling water by stopping the sending of the cooling water to the fuel cell until the temperature of the fuel cell rises. It has been proposed (for example, Patent Document 1).
- the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of suppressing deterioration of a fuel cell in a cold environment.
- the present invention has been made to solve at least a part of the problems described above, and can be realized as the following forms or application examples.
- the fuel cell system of Application Example 1 is a fuel cell system that operates a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen, and includes a cooling pump that sends a cooling medium to the fuel cell; A water removal section for removing water remaining in the cathode catalyst layer formed on the cathode side of the electrolyte membrane in the fuel cell before the cooling pump sends out the cooling medium after the fuel cell is started. It is characterized by that. According to the fuel cell system of Application Example 1, since the water staying in the cathode catalyst layer of the fuel cell is removed before the cooling medium is sent to the fuel cell, the delivery of the cooling medium is started in a cold environment. Even in this case, freezing in the cathode catalyst layer of the fuel cell can be suppressed. As a result, it is possible to suppress deterioration of the fuel cell in a cold environment.
- the fuel cell includes a cathode flow channel that allows an oxidizing gas to flow to the cathode side of the electrolyte membrane, and the dewatering unit is activated after the fuel cell is activated.
- the oxidant gas is introduced into the cathode flow path to remove the water staying in the cathode catalyst layer. Also good.
- moisture in the cathode catalyst layer can be removed using a configuration in which an oxidizing gas is supplied to the fuel cell.
- the flow direction of the cathode channel is upward in the direction of gravity
- the water removal unit is configured so that the cooling pump is operated after the fuel cell is started.
- moisture remaining in the cathode catalyst layer is removed by introducing an oxidizing gas into the cathode flow path in a flow direction downward in the direction of gravity while the current of the fuel cell is stopped. It is also good. Accordingly, moisture in the cathode catalyst layer can be efficiently removed using gravity.
- the fuel cell system further includes a dissolution detection unit that detects the dissolution of water frozen in the cathode catalyst layer, and the water removal unit starts the fuel cell Then, before the cooling pump sends out the cooling medium, when the dissolution detector detects the dissolution of the water, the removal of the water staying in the cathode catalyst layer may be started. According to the fuel cell system of Application Example 3, it is possible to efficiently remove moisture from the cathode catalyst layer that has been frozen when the fuel cell is started.
- the dissolution detection unit may detect the dissolution of water frozen in the cathode catalyst layer based on the internal resistance of the fuel cell. According to the fuel cell system of Application Example 4, it is possible to detect the dissolution of moisture in the cathode catalyst layer with a simpler configuration than providing a temperature sensor in each part of the cathode catalyst layer.
- the fuel cell system further includes a residual water detection unit that detects a residual water amount in the cathode catalyst layer, and the water removal unit detects the residual water.
- the removal of water remaining in the cathode catalyst layer may be terminated based on the amount of remaining water detected by the unit. According to the fuel cell system of Application Example 5, it is possible to prevent the cooling medium from being sent to the fuel cell in a state where moisture is not sufficiently removed from the cathode catalyst layer.
- the fuel cell includes a cathode flow channel for flowing an oxidizing gas to the cathode side of the electrolyte membrane, and the residual water detection unit flows in the cathode flow channel.
- the residual water amount in the cathode catalyst layer may be detected based on the pressure loss of the oxidizing gas. According to the fuel cell system of Application Example 6, the amount of residual water in the cathode catalyst layer can be detected with a simpler configuration than providing a moisture sensor in each part of the cathode catalyst layer 217.
- the residual water detection unit may detect the amount of residual water in the cathode catalyst layer based on the internal resistance of the fuel cell. According to the fuel cell system of Application Example 7, the amount of residual water in the cathode catalyst layer can be detected with a simpler configuration than using a moisture sensor.
- the fuel cell includes an anode catalyst layer formed on the anode side of the electrolyte membrane, and hydrogen on the anode side of the electrolyte membrane.
- the fuel cell introduces an oxidizing gas that introduces an oxidizing gas into a cathode channel formed along the surface direction of the electrolyte membrane.
- a surface of the electrolyte membrane provided on a side corresponding to the oxidizing gas discharge unit, and an oxidizing gas discharge unit that discharges the oxidizing gas from the cathode flow path.
- a cooling introduction part that introduces a cooling medium into a cooling flow path formed along the direction, and a cooling discharge part that is provided on a side corresponding to the oxidizing gas introduction part and discharges the cooling medium from the cooling flow path.
- the oxidation gas is introduced into the oxidizing gas introduction section so that the flow rate of the oxidizing gas is smaller than that during the operation of the cooling pump.
- Ga Reduction unit may be provided with a. According to the fuel cell system of application example 9, avoiding the cooling introduction part side that becomes lower in temperature than the cooling discharge part side with the delivery of the cooling medium, the electrochemical reaction is concentrated on the cooling discharge part side to generate the generated water. By uneven distribution, freezing in the cathode catalyst layer of the fuel cell can be further suppressed.
- the fuel cell introduces an oxidizing gas that introduces an oxidizing gas into a cathode channel formed along the surface direction of the electrolyte membrane.
- a surface of the electrolyte membrane provided on a side corresponding to the oxidizing gas introducing portion, and an oxidizing gas discharging portion that discharges the oxidizing gas from the cathode flow path.
- a cooling introduction section for introducing a cooling medium into a cooling flow path formed along the direction, and a cooling discharge section provided on a side corresponding to the oxidizing gas discharge section and discharging the cooling medium from the cooling flow path.
- the oxidation gas is introduced into the oxidizing gas introduction section so that the flow rate of the oxidizing gas is higher than that during the operation of the cooling pump.
- Scan increasing portion may be provided with a.
- the evaporation of moisture due to the oxidizing gas on the cooling introduction unit side which becomes lower in temperature than the cooling discharge unit side with the delivery of the cooling medium, is promoted, and the cooling discharge unit side is electrically connected. Freezing of the cathode catalyst layer of the fuel cell can be further suppressed by concentrating the chemical reaction to make the generated water unevenly distributed.
- Application Example 11 In the fuel cell system according to any one of Application Examples 1 to 10, the anode side of the electrolyte membrane when the cooling pump delivers the cooling medium after the fuel cell is started.
- a current suppression unit that suppresses the current of the fuel cell may be provided at a current value at which the amount of moisture that moves to the cathode side is less than the amount of moisture that moves to the cathode.
- the cooling medium when the cooling medium is sent to the fuel cell, the amount of water staying in the cathode catalyst layer of the fuel cell is suppressed to generate power. Can be further suppressed.
- the fuel cell operation method of Application Example 12 is a fuel cell operation method for operating a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen, and after the fuel cell is started, Before the cooling medium is sent to the fuel cell, water remaining in the cathode catalyst layer formed on the cathode side of the electrolyte membrane in the fuel cell is removed. According to the operating method of the fuel cell of Application Example 12, since the water staying in the cathode catalyst layer of the fuel cell is removed before the cooling medium is sent to the fuel cell, the cooling medium can be sent out in a cold environment. Even when started, freezing in the cathode catalyst layer of the fuel cell can be suppressed. As a result, it is possible to suppress deterioration of the fuel cell in a cold environment.
- the form of the present invention is not limited to the fuel cell, and may be applied to various forms such as a vehicle that travels using the power of the fuel cell, a power generation system that supplies the power of the fuel cell, and a method for manufacturing the fuel cell. It is also possible to do. Further, the present invention is not limited to the above-described embodiments, and it is needless to say that the present invention can be implemented in various forms without departing from the spirit of the present invention.
- FIG. 1 is an explanatory diagram showing the configuration of the fuel cell system 10.
- the fuel cell system 10 includes a fuel cell 20 that generates electric power by an electrochemical reaction of a reaction gas, and operates the fuel cell 20 to supply electric power to the outside of the fuel cell system 10.
- the fuel cell 20 of the fuel cell system 10 is a solid polymer type fuel cell, and uses a fuel gas containing hydrogen and an oxidizing gas containing oxygen as reaction gases.
- the fuel cell system 10 is a system mounted on a vehicle that travels using the power generated by the fuel cell 20, but as another embodiment, a system installed as a power source for a house or facility.
- the present invention may be applied to a system that is mounted as a power source in an electromechanical device that operates by electricity.
- the fuel cell 20 includes a plurality of single cells 25 constituting a basic structure for taking out electricity directly from a reaction gas, and the plurality of single cells 25 are electrically stacked in series.
- FIG. 2 is an explanatory diagram showing the configuration of the single cell 25 in the fuel cell 20.
- the single cell 25 of the fuel cell 20 includes a membrane electrode assembly (MEA) 210, an anode separator 230, and a cathode separator 240. In the single cell 25, the MEA 210 is sandwiched between the anode separator 230 and the cathode separator 240.
- MEA membrane electrode assembly
- the MEA 210 of the single cell 25 includes an electrolyte membrane 211, an anode electrode 213, and a cathode electrode 216.
- the anode electrode 213 of the MEA 210 includes an anode catalyst layer 214 and an anode diffusion layer 215, and the cathode electrode 216 of the MEA 210 includes a cathode catalyst layer 217 and a cathode diffusion layer 218.
- An anode electrode 213 is bonded to one surface of the electrolyte membrane 211 by laminating an anode catalyst layer 214 and an anode diffusion layer 215 in this order.
- a cathode electrode 216 is bonded to the other surface of the electrolyte membrane 211 by laminating a cathode catalyst layer 217 and a cathode diffusion layer 218 in this order.
- the electrolyte membrane 211 of the MEA 210 is a proton conductor having proton conductivity, and is a perfluorosulfonic acid ion exchange membrane using an ionomer resin in this embodiment.
- the anode catalyst layer 214 and the cathode catalyst layer 217 of the MEA 210 are formed of a material having gas permeability and conductivity and supporting a catalyst (for example, platinum or platinum alloy) that promotes an electrochemical reaction between hydrogen and oxygen. In this embodiment, it is formed of a carbon support carrying a platinum-based catalyst.
- the anode diffusion layer 215 and the cathode diffusion layer 218 of the MEA 210 are made of a material having gas permeability and conductivity.
- the anode diffusion layer 215 and the cathode diffusion layer 218 can be made of carbon cloth or carbon paper which is a carbon porous body.
- the anode separator 230 of the fuel cell 20 forms a plurality of anode channels 235 through which fuel gas flows on the surface of the anode diffusion layer 215 of the MEA 210, and the cathode separator 240 of the fuel cell 20 is the surface of the cathode diffusion layer 218 of the MEA 210.
- a plurality of cathode flow paths 245 through which oxidizing gas flows are formed.
- the anode separator 230 and the cathode separator 240 have sufficient conductivity for collecting electricity generated in the MEA 210 and have sufficient durability, heat resistance, and gas impermeability to flow a reaction gas through the MEA 210.
- the anode separator 230 and the cathode separator 240 are formed of carbon resin.
- the anode separator 230 and the cathode separator 240 may be formed of stainless steel, titanium, a titanium alloy, or conductive ceramics.
- the anode channel 235 and the cathode channel 245 are configured as gaps formed between the MEA 210, but in other embodiments, the anode channel 235 and the cathode channel 245 may be configured by a porous body having a plurality of continuous holes. good.
- the anode separator 230 and the cathode separator 240 are separately configured. However, in other embodiments, the anode separator 230 and the cathode separator 240 may be integrally configured.
- the fuel cell system 10 is configured to operate the fuel cell 20 as a hydrogen gas supply / exhaust unit 30, an oxidizing gas supply / exhaust unit 40, a cooling circulation unit 50, and a power controller 60. And a main control unit 90.
- the hydrogen gas supply / discharge unit 30 of the fuel cell system 10 operates based on an instruction from the main control unit 90, supplies hydrogen gas to the fuel cell 20, and collects used hydrogen gas discharged from the fuel cell 20. To do.
- the hydrogen gas supply / discharge unit 30 supplies hydrogen gas from a tank that compresses and stores hydrogen, but in other embodiments, hydrogen gas may be supplied from a hydrogen storage alloy that stores hydrogen. Alternatively, hydrogen gas may be supplied from a reformer that takes out hydrogen by reforming a hydrocarbon-based fuel such as natural gas, methanol, or gasoline.
- the hydrogen gas supply / discharge unit 30 circulates and reuses the hydrogen gas used in the fuel cell 20.
- the oxidizing gas supply / exhaust unit 40 of the fuel cell system 10 operates based on an instruction from the main control unit 90 to supply the oxidizing gas to the fuel cell 20 and collect the used oxidizing gas discharged from the fuel cell 20. To do.
- the oxidizing gas supply / discharge unit 40 supplies the air taken in from the atmosphere to the fuel cell 20 as the oxidizing gas.
- the cooling circulation unit 50 of the fuel cell system 10 cools the fuel cell 20 by circulating cooling water (antifreeze) that is a cooling medium inside the fuel cell 20.
- the cooling circulation unit 50 includes a cooling pump 540 and a radiator 560.
- the radiator 560 of the cooling circulation unit 50 is a radiator that radiates the heat of the cooling water collected from the fuel cell 20 into the atmosphere.
- the cooling pump 540 of the cooling circulation unit 50 is a pump that operates based on an instruction from the main control unit 90 and sends the cooling water processed by the radiator 560 to the fuel cell 20. Details of the operation of the cooling pump 540 at the start-up of the fuel cell 20 will be described later.
- the power control unit 60 of the fuel cell system 10 is also referred to as a power control unit, and operates based on an instruction from the main control unit 90.
- the connection between the fuel cell 20 and the electric load is turned on and off, and the fuel cell 20 To control the power output to the electrical load.
- the power control unit 60 includes a boost converter that boosts the voltage of DC power from the fuel cell 20 and an inverter that converts the boosted DC power into AC power.
- the fuel cell system 10 includes an AC impedance sensor 810, a temperature sensor 820, an anode pressure sensor 830, and a cathode pressure sensor 840 as various sensors for detecting the state of the fuel cell 20. These sensors are electrically connected to the main controller 90, and output signals from the sensors are transmitted to the main controller 90.
- the AC impedance sensor 810 of the fuel cell system 10 is provided in the fuel cell 20 and detects a cell internal resistance that is an internal resistance (AC impedance) of the single cell 25.
- the temperature sensor 820 of the fuel cell system 10 is provided in the fuel cell 20 and detects the temperature of the fuel cell 20.
- the anode pressure sensor 830 of the fuel cell system 10 is provided in the fuel cell 20 and detects an anode pressure loss that is a differential pressure between the supply pressure and discharge pressure of hydrogen gas.
- the cathode pressure sensor 840 of the fuel cell system 10 is provided in the fuel cell 20 and detects a cathode pressure loss that is a differential pressure between the supply pressure and the discharge pressure of the oxidizing gas.
- the main control unit 90 of the fuel cell system 10 controls each unit of the fuel cell system 10.
- the main control unit 90 is an interface that electrically connects the operation control unit 910 that controls the operation of the fuel cell 20, the storage unit 920 that stores various programs and data, and each unit of the fuel cell system 10. 930.
- the operation control unit 910 of the main control unit 90 includes a water removal control unit 912, a dissolution detection unit 913, and a residual water detection unit 914.
- the function of each unit included in the operation control unit 910 is performed by the operation of a central processing unit (Central Processing Unit) of the operation control unit 910 based on the control program 922 stored in the storage unit 920.
- Central Processing Unit Central Processing Unit
- at least some of the functions of the operation control unit 910 may be realized by an electronic circuit of the operation control unit 910 operating based on its physical circuit configuration.
- the dewatering control unit 912 of the operation control unit 910 removes water remaining in the cathode catalyst layer 217 in the fuel cell 20 after starting the fuel cell 20 and before sending the cooling water to the fuel cell 20 by the cooling pump 540. Execute control to In the present embodiment, in order to remove moisture remaining in the cathode catalyst layer 217, the dewatering control unit 912 disconnects the fuel cell 20 from the electrical load and stops the current of the fuel cell 20 in the fuel cell 20. Control for introducing the reaction gas into the anode channel 235 and the cathode channel 245 is executed.
- the dissolution detection unit 913 of the operation control unit 910 detects the dissolution of water frozen by the cathode catalyst layer 217 of the fuel cell 20. In this embodiment, the dissolution detection unit 913 detects the dissolution of moisture frozen by the cathode catalyst layer 217 based on the cell internal resistance indicated by the output signal from the AC impedance sensor 810. In another embodiment, the dissolution detection unit 913 may detect the dissolution of moisture frozen by the cathode catalyst layer 217 based on the temperature of the fuel cell 20 indicated by the output signal from the temperature sensor 820.
- the residual water detection unit 914 of the operation control unit 910 detects the amount of residual water remaining in the cathode catalyst layer 217 of the fuel cell 20. In the present embodiment, the remaining water detection unit 914 detects the amount of remaining water in the cathode catalyst layer 217 based on the cathode pressure loss indicated by the output signal from the cathode pressure sensor 840. In another embodiment, the remaining water detection unit 914 may detect the amount of remaining water in the cathode catalyst layer 217 based on the cell internal resistance indicated by the output signal from the AC impedance sensor 810.
- the remaining water detection unit 914 may detect the amount of remaining water in the cathode catalyst layer 217 based on the anode pressure loss indicated by the output signal from the anode pressure sensor 830. In another embodiment, the remaining water detection unit 914 may detect the amount of remaining water in the cathode catalyst layer 217 based on the amount of water indicated by the output signal from the moisture sensor provided in the cathode catalyst layer 217.
- FIG. 3 is a flowchart showing a fuel cell activation process (step S10) executed by the operation control unit 910.
- the operation control unit 910 starts the fuel cell activation process (step S10) when the fuel cell 20 is activated.
- step S10 When the fuel cell starting process (step S10) is started, the operation control unit 910 instructs the power control unit 60 to connect an electrical load to the fuel cell 20, and supplies hydrogen gas and oxidizing gas to the fuel cell 20 with hydrogen.
- the fuel cell 20 is activated (step S110).
- step S110 When the fuel cell 20 is activated, power generation by an electrochemical reaction between hydrogen and oxygen is started in the fuel cell 20, and the temperature of the fuel cell 20 is increased by reaction heat accompanying this electrochemical reaction.
- the operation control unit 910 determines whether or not the fuel cell 20 is placed in a cold environment in which moisture remaining on the cathode catalyst layer 217 is frozen (step S120). ). In the present embodiment, the operation control unit 910 determines whether or not it is a cold environment based on the temperature of the fuel cell 20 indicated by the output signal from the temperature sensor 820.
- step S110 When it is determined that it is not a cold environment (step S110: “NO”), the operation control unit 910 instructs the cooling pump 540 to start sending cooling water, thereby starting the cooling pump 540 (step S160). Thereafter, the operation control unit 910 ends the fuel cell activation process (step S10) and executes operation control of the fuel cell 20 according to the required power.
- step S110 when it is determined that the environment is a cold environment (step S110: “YES”), the operation control unit 910 operates as the dissolution detection unit 913 while continuing the power generation by the fuel cell 20, whereby the cathode of the fuel cell 20 is obtained. It is determined whether or not the water frozen in the catalyst layer 217 is dissolved (step S130). In the present embodiment, the operation control unit 910 detects the dissolution of water frozen in the cathode catalyst layer 217 based on the internal resistance of the single cell 25 indicated by the output signal from the AC impedance sensor 810.
- FIG. 4 is an explanatory diagram showing the relationship between the cathode catalyst layer temperature and the cell internal resistance.
- the temperature is set on the horizontal axis and the internal resistance is set on the vertical axis, and the relationship between the cathode catalyst layer temperature that is the temperature of the cathode catalyst layer 217 and the cell internal resistance that is the internal resistance of the single cell 25. Is illustrated.
- the cell internal resistance decreases as the cathode catalyst layer temperature increases.
- the cell internal resistance rapidly decreases to the reference value Thz1, and then the amount of decrease in the cell internal resistance gradually changes.
- the sudden decrease in the cell internal resistance near 0 ° C. is considered to occur because ice near the cathode catalyst layer 217 melts and proton transfer resistance decreases.
- the cell internal resistance indicated by the output signal from the AC impedance sensor 810 is the reference value Thz1. In the following case, it is determined that the water frozen in the cathode catalyst layer 217 is dissolved.
- step S 140 when the dissolution of moisture in the cathode catalyst layer 217 is detected (step S ⁇ b> 130: “YES”), the operation control unit 910 stays in the cathode catalyst layer 217 by operating as the water removal control unit 912.
- the water removal process (step S140) for removing the moisture to be performed is executed.
- FIG. 5 is a flowchart showing details of the water removal process (step S140).
- the operation control unit 910 executes a purge process (step S145).
- the operation control unit 910 instructs the power control unit 60 to temporarily disconnect the electrical load from the fuel cell 20, and temporarily stops the current of the fuel cell 20. While the current of the fuel cell 20 is temporarily stopped, the operation control unit 910 continues to instruct the hydrogen gas supply / discharge unit 30 and the oxidant gas supply / discharge unit 40 to supply the reaction gas to the fuel cell 20, Hydrogen gas is introduced into the anode channel 235 and oxidizing gas is introduced into the cathode channel 245.
- step S145 the water in the anode channel 235 is removed by hydrogen gas and the moisture in the cathode channel 245 is removed by oxidizing gas while the generation of generated water accompanying power generation is temporarily stopped. . In this way, as the moisture is removed from the anode channel 235 and the cathode channel 245, the moisture remaining in the cathode catalyst layer 217 can be removed.
- step S145 since the power generation by the fuel cell 20 is performed intermittently even during the purge process (step S145), the temperature of the fuel cell 20 continues to rise intermittently due to the reaction heat.
- both hydrogen gas and oxidizing gas are introduced in the purge process (step S145).
- one of hydrogen gas and oxidizing gas may be introduced.
- the operation control unit 910 operates as the residual water detection unit 914 to determine whether or not the residual water amount remaining in the cathode catalyst layer 217 of the fuel cell 20 is equal to or less than a reference value.
- the operation control unit 910 detects the amount of residual water in the cathode catalyst layer 217 based on the pressure loss of the oxidizing gas indicated by the output signal from the cathode pressure sensor 840. If the remaining water amount in the cathode catalyst layer 217 is not less than the reference value (step S148: “NO”), the operation control unit 910 continues the water removal treatment (step S140), and the remaining water amount in the cathode catalyst layer 217 is less than the reference value. (Step S148: “YES”), the water removal process (step S140) is terminated.
- FIG. 6 is an explanatory diagram showing changes in anode pressure loss, cathode pressure loss, and cell internal resistance in the water removal treatment (step S140).
- the time is set on the horizontal axis
- the pressure loss and the internal resistance are set on the vertical axis
- the anode pressure loss which is the pressure loss of the anode flow path 235
- changes with time and the pressure loss of the cathode flow path 245.
- the time change of the cathode pressure loss and the time change of the cell internal resistance, which is the internal resistance of the single cell 25, are respectively illustrated.
- the cathode pressure loss increases from the start of the supply of the oxidizing gas to the maximum value due to the influence of moisture staying in the cathode channel 245, and decreases the amount of moisture staying in the cathode channel 245. It decreases with it. Thereafter, when water removal from the cathode channel 245 is completed, water removal from the cathode electrode 216 through the cathode channel 245 starts, and the cathode pressure loss gradually decreases as the amount of water remaining in the cathode electrode 216 decreases. descend. Thereafter, when the water removal up to the cathode catalyst layer 217 in the cathode electrode 216 is completed, the cathode pressure loss is stabilized at the reference value Thc.
- the operation control unit 910 causes the cathode catalyst layer 217 when the pressure loss of the oxidizing gas indicated by the output signal from the cathode pressure sensor 840 is stabilized at the reference value Thc. It is judged that the amount of residual water remaining in the water has become below the reference value.
- the anode pressure loss increases from the start of hydrogen gas supply to a maximum value due to the influence of moisture staying in the anode flow path 235, and decreases the amount of water staying in the anode flow path 235. It decreases with it. Then, following the completion of water removal from the cathode channel 245, water removal from the cathode electrode 216 begins via the anode electrode 213 and the electrolyte membrane 211, and the anode pressure loss is caused by a decrease in the amount of water remaining in the cathode electrode 216. Along with this, it decreases gradually.
- the operation control unit 910 causes the cathode catalyst layer when the hydrogen gas pressure loss indicated by the output signal from the anode pressure sensor 830 is stabilized at the reference value Tha. It may be determined that the amount of residual water remaining in 217 has become equal to or less than a reference value. As shown in FIG.
- the cathode pressure loss is more preferably used to determine the moisture content of the cathode electrode 216. preferable.
- the internal resistance of the cell is stabilized at a constant value due to the influence of water remaining in the MEA 210 until the water frozen from the cathode catalyst layer 217 is dissolved and the water removal from the cathode electrode 216 is started. Thereafter, when water removal from the cathode electrode 216 starts, the cell internal resistance rapidly increases as the amount of water remaining in the cathode electrode 216 decreases. The cell internal resistance reaches the reference value Thz2 at the time when the water removal up to the cathode catalyst layer 217 in the cathode electrode 216 is completed, and then gradually increases as the amount of water in the MEA 210 decreases. In another embodiment, from the characteristics of the fuel cell 20 shown in FIG.
- the operation control unit 910 causes the cathode catalyst layer 217 when the cell internal resistance indicated by the output signal from the AC impedance sensor 810 is equal to or higher than the reference value Thz2. It may be determined that the amount of residual water remaining in the water is below a reference value. In another embodiment, the remaining water amount of the cathode catalyst layer 217 may be detected based on at least two of the anode pressure loss, the cathode pressure loss, and the cell internal resistance.
- step S150 determines whether or not the temperature of the fuel cell 20 is equal to or higher than a reference value.
- the operation control unit 910 Judge that the temperature is above the reference value.
- step S150: “NO” the operation control unit 910 performs the water removal process (step S140) again.
- step S150 When the temperature of the fuel cell 20 is equal to or higher than the reference value (step S150: “YES”), the operation control unit 910 activates the cooling pump 540 (step S160). Thereafter, the operation control unit 910 ends the fuel cell activation process (step S10) and executes operation control of the fuel cell 20 according to the required power.
- FIG. 7 is an explanatory diagram showing a temperature change of the fuel cell 20 in the fuel cell activation process (step S10).
- time is set on the horizontal axis and temperature is set on the vertical axis, and the time change of the temperature in the fuel cell 20 is illustrated.
- the fuel cell activation process step S10 is started in a cold environment (timing t0 in FIG. 7)
- the temperature of the fuel cell 20 rises from below the freezing point due to reaction heat accompanying power generation.
- the temperature of the fuel cell 20 exceeds 0 ° C. (timing t1 in FIG. 7) and the water removal treatment (step S140) is started in accordance with the melting of ice in the cathode catalyst layer 217, the temperature of the fuel cell 20 rises.
- step S140 hydrogen gas is introduced into the anode channel 235 and oxidizing gas is introduced into the cathode channel 245 to remove moisture from the cathode catalyst layer 217 (step S145).
- the water in the cathode catalyst layer 217 can be removed using the configuration in which the reaction gas is supplied to the fuel cell 20.
- the moisture of the cathode catalyst layer 217 that has been frozen when the fuel cell 20 is started up is removed. It can be removed efficiently. Further, in order to detect the dissolution of the water frozen in the cathode catalyst layer 217 based on the internal resistance of the fuel cell 20, the configuration of the cathode catalyst layer 217 is simpler than that provided with a temperature sensor in each part of the cathode catalyst layer 217. The dissolution of moisture can be detected.
- the cathode catalyst layer 217 In addition, the amount of water remaining in the cathode catalyst layer 217 is detected (step S145), and the water removal process (step S140) is terminated. Therefore, the fuel cell 20 is cooled in a state where moisture removal from the cathode catalyst layer 217 is insufficient. Water can be prevented from being sent out. Further, in order to detect the amount of remaining water in the cathode catalyst layer 217 based on the pressure loss of the oxidizing gas flowing through the cathode channel 245, the cathode catalyst layer has a simpler configuration than that provided with a moisture sensor in each part of the cathode catalyst layer 217. The amount of residual water in 217 can be detected.
- FIG. 8 is an explanatory diagram showing the direction in which the reaction gas flows in the second embodiment.
- FIG. 8 illustrates the direction in which the reactive gas flows during normal power generation and the direction in which the reactive gas flows in the purge process (step S145).
- the direction in which hydrogen gas flows through the anode channel 235 is downward in the direction of gravity toward the gravity direction G, and the direction in which oxidizing gas flows through the cathode channel 245 is opposite to the direction of gravity G. It is upward in the direction of gravity.
- the direction in which the hydrogen gas flows through the anode channel 235 is switched downward in the direction of gravity while the direction in which the oxidizing gas flows through the cathode channel 245 is switched downward in the direction of gravity.
- the direction in which the oxidizing gas flows through the cathode flow path 245 is switched downward in the gravity direction by switching the pipe connecting the oxidizing gas supply / discharge unit 40 and the fuel cell 20.
- the deterioration of the fuel cell 20 in a cold environment can be suppressed as in the first embodiment. Further, since the oxidizing gas is allowed to flow downward in the gravity direction in the purge process (step S145), moisture in the cathode catalyst layer 217 can be efficiently removed using gravity.
- FIG. 9 is a flowchart showing details of the water removal process (step S140) in the third embodiment.
- the water removal treatment (step S140) of the third embodiment is the same as that of the first embodiment except that the method for removing moisture from the cathode catalyst layer 217 is different.
- the operation control unit 910 instructs the hydrogen gas supply / discharge unit 30 to increase the stoichiometric ratio of the hydrogen gas while continuing the power generation by the fuel cell 20, whereby the cathode catalyst layer.
- the amount of water that moves from 217 to the anode catalyst layer 214 is increased (step S146).
- the stoichiometric ratio of hydrogen gas is the ratio of the amount of gas actually supplied to the minimum amount of gas required for the amount of power generation. The larger the stoichiometric ratio, the more excessive the supply.
- FIG. 10 is an explanatory view showing the state of water removal treatment (step S140) in the third embodiment.
- FIG. 10 shows the vicinity of the electrolyte membrane 211 before and during the water removal treatment.
- the anode catalyst layer 214 is formed of catalyst-carrying carbon 224, and a gap is formed between the catalyst-carrying carbons 224.
- the cathode catalyst layer 217 is formed of catalyst-supporting carbon 227, and a gap is formed between the catalyst-supporting carbons 227.
- Generated water accompanying power generation is generated on the catalyst-supporting carbon 227 of the anode catalyst layer 214.
- step S140 the stoichiometric ratio of the hydrogen gas is increased and the flow rate of the hydrogen gas is increased, so that the amount of water taken by the hydrogen gas from the anode catalyst layer 214 is also increased.
- moisture staying in the cathode catalyst layer 217 passes through the electrolyte membrane 211 and moves to the anode catalyst layer 214.
- the deterioration of the fuel cell 20 in a cold environment can be suppressed as in the first embodiment.
- the water gas is removed from the cathode catalyst layer 217 by increasing the stoichiometric ratio of hydrogen gas and increasing the amount of moisture that moves from the cathode catalyst layer 217 to the anode catalyst layer 214.
- Step S146 Using the configuration for supplying hydrogen gas to the fuel cell 20, moisture in the cathode catalyst layer 217 can be removed while power generation is continued.
- the fuel cell system 10 of the fourth embodiment is the same as that of the first embodiment except that the configuration relating to the hydrogen gas supply / exhaust section 30 and the operation of the water removal treatment (step S140) are different.
- FIG. 11 is an explanatory diagram showing the hydrogen gas supply / discharge part 30 in the fourth embodiment.
- the configuration of the fuel cell system 10 of the fourth embodiment is the same as that of the first embodiment except that a heating unit 370 for heating the hydrogen gas supplied from the hydrogen gas supply / exhaust unit 30 to the fuel cell 20 is provided.
- the heating unit 370 is an electric heater disposed around a pipe for supplying hydrogen gas, and operates based on an instruction from the operation control unit 910.
- FIG. 12 is a flowchart showing details of the water removal treatment (step S140) in the fourth embodiment.
- the water removal treatment (step S140) of the fourth embodiment is the same as that of the first embodiment except that the method for removing moisture from the cathode catalyst layer 217 is different.
- the operation control unit 910 instructs the heating unit 370 to heat the hydrogen gas while continuing the power generation by the fuel cell 20, whereby the cathode catalyst layer 217 to the anode catalyst layer 214 are operated.
- the amount of moisture transferred to is increased (step S147).
- step S140 When the water removal treatment (step S140) is started, the temperature of the hydrogen gas rises and the saturated vapor partial pressure of the hydrogen gas increases, so that the amount of moisture taken away from the anode catalyst layer 214 also increases. Along with this, as in the third embodiment shown in FIG. 10, the moisture staying in the cathode catalyst layer 217 passes through the electrolyte membrane 211 and moves to the anode catalyst layer 214.
- the deterioration of the fuel cell 20 in a cold environment can be suppressed as in the first embodiment.
- the temperature of the hydrogen gas is increased to increase the amount of moisture that moves from the cathode catalyst layer 217 to the anode catalyst layer 214, thereby removing moisture from the cathode catalyst layer 217 (
- step S147) using the configuration in which hydrogen gas is supplied to the fuel cell 20, moisture in the cathode catalyst layer 217 can be removed while power generation is continued.
- Example 5 The fuel cell system 10 of the fifth embodiment is the same as that of the first embodiment except that the flow of the oxidizing gas to the MEA 20 is different.
- FIG. 13 is an explanatory diagram showing the single cell 25 viewed from the stacking direction in the fifth embodiment.
- the single cell 25 includes six hole portions 261 to 266 that respectively form holes penetrating in the stacking direction.
- the holes 261, 262, and 263 are provided along one short side of the rectangular single cell 25, and the holes 264, 265, and 266 are provided along the other short side of the rectangular single cell 25. Yes.
- the hole portion 261 is a cooling water introduction portion that introduces cooling water into the single cell 25 and constitutes a part of a flow path for flowing cooling water to be introduced into each of the plurality of single cells 25 in the fuel cell 20.
- the hole portion 262 is an oxidizing gas discharge portion that discharges the oxidizing gas from the single cell 25 and constitutes a part of a flow path through which the oxidizing gas discharged from each of the plurality of single cells 25 in the fuel cell 20 flows.
- the hole 263 is a hydrogen gas introduction part that introduces hydrogen gas into the single cell 25 and constitutes a part of a flow path for flowing hydrogen gas to be introduced into each of the plurality of single cells 25 in the fuel cell 20. .
- the hole portion 264 is a hydrogen gas discharge portion that discharges hydrogen gas from the single cell 25 and constitutes a part of a flow path through which the hydrogen gas discharged from each of the plurality of single cells 25 in the fuel cell 20 flows.
- the hole portion 265 is an oxidizing gas introducing portion that introduces the oxidizing gas into the single cell 25 and constitutes a part of a flow path for flowing the oxidizing gas to be introduced into each of the plurality of single cells 25 in the fuel cell 20.
- the hole portion 266 is a cooling water discharge portion that discharges the cooling water from the single cell 25 and constitutes a part of a flow path for flowing the cooling water discharged from each of the plurality of single cells 25 in the fuel cell 20.
- the flow of the hydrogen gas is opposed to the flow of the oxidizing gas and flows from the hydrogen gas upstream portion 271 of the single cell 25 to the hydrogen gas downstream portion 272.
- the flow of the oxidizing gas is illustrated using white arrows, and the flow of the cooling water is illustrated using wavy lines.
- the oxidizing gas flows from the hydrogen gas downstream portion 272 to the hydrogen gas upstream portion 271 facing the flow of hydrogen gas, and the cooling water faces the hydrogen gas upstream portion facing the flow of the oxidizing gas. From 271 to the hydrogen gas downstream portion 272.
- FIG. 14 is a flowchart showing a fuel cell activation process (step S10) in the fifth embodiment.
- step S10 when the dissolution of moisture in the cathode catalyst layer 217 is detected (step S130: “YES”), the flow rate of the oxidizing gas during power generation by the fuel cell 20 is determined during normal power generation.
- the flow rate is the same as that of the first embodiment except that the flow rate is set lower (step S135).
- the electrochemical reaction between hydrogen and oxygen is concentrated not on the hydrogen gas upstream portion 271 side where the cooling water flows but on the hydrogen gas downstream portion 272 side, and the generated water accompanying power generation is concentrated on the hydrogen gas downstream portion 272 side. It can be unevenly distributed.
- the deterioration of the fuel cell 20 in a cold environment can be suppressed as in the first embodiment. Further, in order to make the generated water unevenly distributed by concentrating the electrochemical reaction on the hydrogen gas downstream portion 272 side, avoiding the hydrogen gas upstream portion 271 side which becomes lower in temperature than the hydrogen gas downstream portion 272 side as the cooling water is delivered. Further, freezing in the cathode catalyst layer 217 of the fuel cell 20 can be further suppressed.
- Example 6 The fuel cell system 10 of the sixth embodiment is the same as that of the fifth embodiment except that the flow of oxidizing gas and cooling water to the MEA 20 is different.
- FIG. 15 is an explanatory diagram showing the single cell 25 viewed from the stacking direction in the sixth embodiment.
- the configuration of the single cell 25 is the same as that of the fifth embodiment except that the direction in which the cooling water flows is opposite to that of the fifth embodiment.
- the hole portion 261 is a cooling water discharge portion that discharges cooling water from the single cell 25, and the hole portion 266 is a cooling water introduction portion that introduces cooling water into the single cell 25.
- the flow directions of the hydrogen gas and the oxidizing gas are the same as those in the fifth embodiment, and the cooling water flows from the hydrogen gas downstream portion 272 to the hydrogen gas upstream portion 271 in the same manner as the flow of the oxidizing gas.
- FIG. 16 is a flowchart showing the fuel cell activation process (step S10) in the sixth embodiment.
- step S10 when the dissolution of moisture in the cathode catalyst layer 217 is detected (step S130: “YES”), the flow rate of the oxidizing gas during power generation by the fuel cell 20 is determined during normal power generation. Except for the point that the flow rate is set higher than that (step S136), it is the same as the first embodiment.
- the deterioration of the fuel cell 20 in a cold environment can be suppressed as in the first embodiment.
- the evaporation of moisture by the oxidizing gas on the hydrogen gas downstream portion 272 side which becomes lower than the hydrogen gas upstream portion 271 side with the delivery of cooling water, is promoted, and an electrochemical reaction is performed on the hydrogen gas upstream portion 271 side. Since the generated water is concentrated and concentrated, freezing in the cathode catalyst layer 217 of the fuel cell 20 can be further suppressed.
- FIG. 17 is a flowchart showing the fuel cell activation process (step S10) in the seventh embodiment.
- the operation control unit 910 instructs the power control unit 60 to suppress the current of the fuel cell 20 to the current value Thi (step S160).
- the current value Thi is a current value at which the amount of water that moves to the cathode electrode 216 side becomes smaller than the amount of water that moves to the anode electrode 213 side.
- FIG. 18 is an explanatory diagram showing the relationship between the current density of the MEA 210 and the damage time of the cathode catalyst layer 217 in the sub-freezing region.
- the current density is set on the horizontal axis and the time is set on the vertical axis, and the relationship between the current density of the MEA 210 and the damage time of the cathode catalyst layer 217 in the sub-freezing region is illustrated.
- the time until the cathode catalyst layer 217 is damaged increases as the current density of the MEA 210 decreases, and dramatically increases when the current density of the MEA 210 decreases below the reference value CD1.
- FIG. 19 is an explanatory diagram showing how moisture moves in the MEA 210.
- FIG. 19 illustrates a state where the current density of the MEA 210 is the reference value CD1, and a state where the current density of the MEA 210 is the reference value CD2 which is larger than the reference value CD1.
- the electroosmotic water W1 shown in FIG. 19 is water that moves together with protons in the electrolyte membrane 211 from the anode catalyst layer 214 side to the cathode catalyst layer 217 side, and increases as the current density of the MEA 210 increases.
- the reverse diffusion water W2 shown in FIG. 19 is water that moves the electrolyte membrane 211 from the cathode catalyst layer 217 side to the anode catalyst layer 214 side due to the water vapor partial pressure difference.
- the electroosmotic water W1 is less than the reverse diffusion water W2. Accordingly, it is considered that the amount of moisture that moves to the cathode catalyst layer 217 and freezes is suppressed, and the time until the cathode catalyst layer 217 is damaged is extended.
- the electroosmotic water W1 is larger than the reverse diffusion water W2. For this reason, it is considered that the moisture that moves to the cathode catalyst layer 217 freezes one after another in the cathode catalyst layer 217 and promotes damage to the cathode catalyst layer 217.
- FIG. 20 is an explanatory view showing a temperature change of the fuel cell 20 in the seventh embodiment.
- the time is set on the horizontal axis
- the temperature and the current are set on the vertical axis
- the time change of the temperature and current in the fuel cell 20 is illustrated.
- the temperature of the fuel cell 20 is indicated by a solid line
- the current of the fuel cell 20 is indicated by a one-dot chain line.
- the temperature change of the fuel cell 20 is the same as that of the first embodiment shown in FIG.
- step S10 when the fuel cell activation process (step S10) is started in a cold environment (timing t0 in FIG. 20), the current of the fuel cell 20 starts to rise. Thereafter, when the cooling pump 540 is started (timing t2 in FIG. 20), the current of the fuel cell 20 is changed to the current value Thi where the current density of the MEA 210 becomes the reference value CD1 by the current suppression of the fuel cell 20 (step S160). It is suppressed.
- the timing for executing the current suppression (step S160) of the fuel cell 20 is earlier than the timing (timing t3 in FIG. 20) at which the temperature of the fuel cell 20 decreases again to below the freezing point as the cooling water is sent out.
- the cooling pump 540 is not started (step S160). However, in another embodiment, the cooling pump 540 may be started (step S160).
- the fuel cell activation process step S10 is completed, the current of the fuel cell 20 rises to a current value corresponding to the required power.
- the deterioration of the fuel cell 20 in a cold environment can be suppressed as in the first embodiment.
- the amount of water staying in the cathode catalyst layer 217 of the fuel cell 20 is suppressed to generate power, and thus freezing in the cathode catalyst layer 217 of the fuel cell 20 is further suppressed. be able to.
- the water removal treatment (step S140) is started after detecting the dissolution of the frozen water in the cathode catalyst layer 217 (step S130).
- the cathode catalyst layer 217 is used.
- the water removal treatment (step S140) may be started in accordance with the activation of the fuel cell 20 without waiting for the water that has been frozen in step 1 to be dissolved. Thereby, the generated water generated after the start of the fuel cell 20 can be removed at an early stage.
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Abstract
Description
A-1.燃料電池システムの構成:
図1は、燃料電池システム10の構成を示す説明図である。燃料電池システム10は、反応ガスの電気化学反応によって発電する燃料電池20を備え、燃料電池システム10の外部に電力を供給するために燃料電池20を運転する。本実施例では、燃料電池システム10の燃料電池20は、固体高分子型の燃料電池であり、水素を含有する燃料ガス、および酸素を含有する酸化ガスを反応ガスとして用いる。本実施例では、燃料電池システム10は、燃料電池20で発電した電力を利用して走行する車両に搭載されるシステムであるが、他の実施形態として、住宅や施設の電源として設置されるシステムに適用しても良いし、電気で作動する電気機械機器に電源として搭載されるシステムに適用しても良い。
図3は、運転制御部910が実行する燃料電池起動処理(ステップS10)を示すフローチャートである。本実施例では、運転制御部910は、燃料電池20を起動する際に、燃料電池起動処理(ステップS10)を開始する。
以上説明した第1実施例の燃料電池システム10によれば、燃料電池20に冷却水が送出される前に、燃料電池20のカソード触媒層217に滞留する水分が除去されるため、寒冷環境下で冷却水の送出が開始された場合であっても、燃料電池20のカソード触媒層217における凍結を抑制することができる。その結果、寒冷環境下での燃料電池20の劣化を抑制することができる。
第2実施例の燃料電池システム10は、パージ処理(ステップS145)においてカソード流路245に酸化ガスを流す方向が異なる点を除き、第1実施例と同様である。図8は、第2実施例において反応ガスを流す方向を示す説明図である。図8には、通常発電時に反応ガスを流す方向と、パージ処理(ステップS145)において反応ガスを流す方向とを図示した。燃料電池20による発電中、アノード流路235に水素ガスを流す方向は、重力方向Gに向かう重力方向下向きであり、カソード流路245に酸化ガスを流す方向は、重力方向Gとは逆に向かう重力方向上向きである。第2実施例では、パージ処理(ステップS145)において、アノード流路235に水素ガスを流す方向は重力方向下向きのまま、カソード流路245に酸化ガスを流す方向を重力方向下向きに切り換える。本実施例では、酸化ガス給排部40と燃料電池20とを接続する配管を切り換えることによって、カソード流路245に酸化ガスを流す方向を重力方向下向きに切り換える。
第3実施例の燃料電池システム10は、除水処理(ステップS140)の動作が異なる点を除き、第1実施例と同様である。図9は、第3実施例における除水処理(ステップS140)の詳細を示すフローチャートである。第3実施例の除水処理(ステップS140)は、カソード触媒層217から水分を除去する手法が異なる点を除き、第1実施例と同様である。除水処理(ステップS140)を開始すると、運転制御部910は、燃料電池20による発電を継続させながら、水素ガスのストイキ比の上昇を水素ガス給排部30に指示することによって、カソード触媒層217からアノード触媒層214に移動する水分量を増加させる(ステップS146)。なお、水素ガスのストイキ比とは、発電量に必要な最小のガス量に対する実際に供給されるガス量の比率であり、ストイキ比が大きくなる程、供給過大であること示す。
第4実施例の燃料電池システム10は、水素ガス給排部30に関する構成、および除水処理(ステップS140)の動作が異なる点を除き、第1実施例と同様である。図11は、第4実施例における水素ガス給排部30を示す説明図である。第4実施例の燃料電池システム10の構成は、水素ガス給排部30から燃料電池20に供給される水素ガスを加熱する加熱部370を備える点を除き、第1実施例と同様である。本実施例では、加熱部370は、水素ガスを供給する配管の周囲に配置された電熱器であり、運転制御部910からの指示に基づいて動作する。
第5実施例の燃料電池システム10は、MEA20に対する酸化ガスの流し方が異なる点を除き、第1実施例と同様である。図13は、第5実施例における積層方向から見た単セル25を示す説明図である。単セル25は、積層方向に貫通する孔をそれぞれ形成する六個の孔部261~266を備える。孔部261,262,263は、長方形の単セル25における一方の短辺に沿って設けられ、孔部264,265,266は、長方形の単セル25における他方の短辺に沿って設けられている。
第6実施例の燃料電池システム10は、MEA20に対する酸化ガスおよび冷却水の流し方が異なる点を除き、第5実施例と同様である。図15は、第6実施例における積層方向から見た単セル25を示す説明図である。単セル25の構成は、冷却水を流す方向が第5実施例とは逆である点を除き、第5実施例と同様である。第6実施例では、孔部261は、単セル25から冷却水を排出する冷却水排出部であり、孔部266は、単セル25に冷却水を導入する冷却水導入部である。第6実施例では、水素ガスおよび酸化ガスの流れ方向は、第5実施例と同様であり、冷却水は、酸化ガスの流れと同様に水素ガス下流部272から水素ガス上流部271に流れる。
第7実施例の燃料電池システム10は、燃料電池起動処理(ステップS10)の動作が異なる点を除き、第1実施例と同様である。図17は、第7実施例における燃料電池起動処理(ステップS10)を示すフローチャートである。第7実施例では、冷却ポンプ540を起動する際(ステップS160)、運転制御部910は、電力制御部60に指示することによって、燃料電池20の電流を電流値Thiに抑制する(ステップS160)。電流値Thiは、カソード電極216側に移動する水分量がアノード電極213側に移動する水分量よりも少なくなる電流値である。
以上、本発明の実施の形態について説明したが、本発明はこうした実施の形態に何ら限定されるものではなく、本発明の趣旨を逸脱しない範囲内において様々な形態で実施し得ることは勿論である。例えば、第1実施例ないし第7実施例の少なくとも二つの実施例を適宜組み合わせて適用しても良い。また、上述の実施例では、除水処理(ステップS140)を、カソード触媒層217で凍結した水分の溶解を検知した後(ステップS130)に開始したが、他の実施形態において、カソード触媒層217で凍結した水分の溶解を待つことなく、燃料電池20の起動に合わせて除水処理(ステップS140)を開始しても良い。これによって、燃料電池20の起動後に発生する生成水を早期に除去することができる。
Claims (12)
- 水素と酸素との電気化学反応によって発電する燃料電池を運転する燃料電池システムであって、
前記燃料電池に冷却媒体を送出する冷却ポンプと、
前記燃料電池が起動した後、前記冷却ポンプが前記冷却媒体を送出する前に、前記燃料電池における電解質膜のカソード側に形成されたカソード触媒層に滞留する水分を除去する除水部と
を備える燃料電池システム。 - 請求項1に記載の燃料電池システムであって、
前記燃料電池は、前記電解質膜の前記カソード側に酸化ガスを流すカソード流路を含み、
前記除水部は、前記燃料電池が起動した後、前記冷却ポンプが前記冷却媒体を送出する前に、前記燃料電池の電流を停止した状態で、前記カソード流路に酸化ガスを導入することによって、前記カソード触媒層に滞留する水分を除去する、燃料電池システム。 - 請求項1または請求項2に記載の燃料電池システムであって、
更に、前記カソード触媒層で凍結した水分の溶解を検知する溶解検知部を備え、
前記除水部は、前記燃料電池が起動した後、前記冷却ポンプが前記冷却媒体を送出する前に、前記溶解検知部が前記水分の溶解を検知した場合、前記カソード触媒層に滞留する水分の除去を開始する、燃料電池システム。 - 前記溶解検知部は、前記燃料電池の内部抵抗に基づいて、前記カソード触媒層で凍結した水分の溶解を検知する、請求項3に記載の燃料電池システム。
- 請求項1ないし請求項4のいずれか一項に記載の燃料電池システムであって、
更に、前記カソード触媒層における残水量を検知する残水検知部を備え、
前記除水部は、前記残水検知部によって検知された残水量に基づいて、前記カソード触媒層に滞留する水分の除去を終了する、燃料電池システム。 - 請求項5に記載の燃料電池システムであって、
前記燃料電池は、前記電解質膜の前記カソード側に酸化ガスを流すカソード流路を含み、
前記残水検知部は、前記カソード流路を流れる酸化ガスの圧力損失に基づいて、前記カソード触媒層における残水量を検知する、燃料電池システム。 - 前記残水検知部は、前記燃料電池の内部抵抗に基づいて、前記カソード触媒層における残水量を検知する、請求項5に記載の燃料電池システム。
- 請求項1ないし請求項7のいずれか一項に記載の燃料電池システムであって、
前記燃料電池は、
前記電解質膜のアノード側に形成されたアノード触媒層と、
前記電解質膜の前記アノード側に水素ガスを流すアノード流路と
を含み、
前記除水部は、前記アノード流路に流れる水素ガスのストイキ比および温度の少なくとも一方を上昇させ、前記カソード触媒層から前記アノード触媒層に移動する水分量を増加させることによって、前記カソード触媒層に滞留する水分を除去する、燃料電池システム。 - 請求項1ないし請求項8のいずれか一項に記載の燃料電池システムであって、
前記燃料電池は、
前記電解質膜の面方向に沿って形成されたカソード流路に酸化ガスを導入する酸化ガス導入部と、
前記酸化ガス導入部に対向する位置に設けられ、前記カソード流路から酸化ガスを排出する酸化ガス排出部と、
前記酸化ガス排出部に対応する側に設けられ、前記電解質膜の面方向に沿って形成された冷却流路に冷却媒体を導入する冷却導入部と、
前記酸化ガス導入部に対応する側に設けられ、前記冷却流路から冷却媒体を排出する冷却排出部と
を含み、
更に、前記燃料電池が起動した後、前記冷却ポンプが前記冷却媒体を送出する前に、前記酸化ガス導入部に導入される酸化ガスの流量を、前記冷却ポンプの稼働時よりも減少させる酸化ガス減少部を備える燃料電池システム。 - 請求項1ないし請求項8のいずれか一項に記載の燃料電池システムであって、
前記燃料電池は、
前記電解質膜の面方向に沿って形成されたカソード流路に酸化ガスを導入する酸化ガス導入部と、
前記酸化ガス導入部に対向する位置に設けられ、前記カソード流路から酸化ガスを排出する酸化ガス排出部と、
前記酸化ガス導入部に対応する側に設けられ、前記電解質膜の面方向に沿って形成された冷却流路に冷却媒体を導入する冷却導入部と、
前記酸化ガス排出部に対応する側に設けられ、前記冷却流路から冷却媒体を排出する冷却排出部と
を含み、
更に、前記燃料電池が起動した後、前記冷却ポンプが前記冷却媒体を送出する前に、前記酸化ガス導入部に導入される酸化ガスの流量を、前記冷却ポンプの稼働時よりも増加させる酸化ガス増加部を備える燃料電池システム。 - 更に、前記燃料電池が起動した後、前記冷却ポンプが前記冷却媒体を送出する際に、前記電解質膜のアノード側に移動する水分量よりも前記カソード側に移動する水分量が少なくなる電流値に、前記燃料電池の電流を抑制する電流抑制部を備える請求項1ないし請求項10のいずれか一項に記載の燃料電池システム。
- 水素と酸素との電気化学反応によって発電する燃料電池を運転する燃料電池の運転方法であって、
前記燃料電池を起動した後、前記燃料電池に冷却媒体を送出する前に、前記燃料電池における電解質膜のカソード側に形成されたカソード触媒層に滞留する水分を除去する、燃料電池の運転方法。
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EP10853180.7A EP2584637B1 (en) | 2010-06-17 | 2010-06-17 | Fuel cell |
US13/702,242 US8980486B2 (en) | 2010-06-17 | 2010-06-17 | Fuel cell |
CN201080067453.6A CN102947993B (zh) | 2010-06-17 | 2010-06-17 | 燃料电池 |
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JP2015220198A (ja) * | 2014-05-21 | 2015-12-07 | トヨタ自動車株式会社 | 燃料電池システム及びその制御方法 |
WO2021010065A1 (ja) * | 2019-07-16 | 2021-01-21 | 株式会社デンソー | 燃料電池システム |
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CN106876751B (zh) * | 2017-02-14 | 2020-11-10 | 北京东方华氢科技有限公司 | 一种氢氧燃料电池 |
JP6996430B2 (ja) * | 2018-06-12 | 2022-02-04 | トヨタ自動車株式会社 | 燃料電池セルおよび燃料電池スタック |
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