JP2022069754A - Fuel cell system - Google Patents

Abstract

To detect a time until a cross leak occurs during power generation of a fuel cell in a short time.SOLUTION: A fuel cell system stores, in advance, a data group showing the correlation between the proton resistance of an electrolyte membrane during power generation of a fuel cell at a predetermined temperature of the fuel cell and a predetermined relative humidity of fuel gas and oxidant gas, and a time until a cross leak occurs, collates the measured proton resistance with the data group after the start of power generation of the fuel cell, and detects the time until the cross leak occurs.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a fuel cell system.

A fuel cell (FC) is used as a fuel gas in a fuel cell stack (hereinafter, may be simply referred to as a stack) in which one single cell or a plurality of single cells (hereinafter, may be referred to as a cell) are laminated. It is a power generation device that extracts electric energy by an electrochemical reaction between hydrogen (H ₂ ) and oxygen (O ₂ ) as an oxidizing agent gas. In the following, the fuel gas and the oxidant gas may be simply referred to as "reaction gas" or "gas" without particular distinction.
A single cell of this fuel cell is usually composed of a membrane electrode assembly (MEA: Membrane Electrode Assembly) and, if necessary, two separators sandwiching both sides of the membrane electrode assembly.
The membrane electrode assembly has a structure in which a catalyst layer and a gas diffusion layer are sequentially formed on both sides of a solid polymer electrolyte membrane having proton (H ⁺ ) conductivity (hereinafter, also simply referred to as “electrolyte membrane”), respectively. have. Therefore, the membrane electrode assembly may be referred to as a membrane electrode gas diffusion layer assembly (MEGA).
The separator usually has a structure in which a groove as a flow path of the reaction gas is formed on the surface in contact with the gas diffusion layer. This separator also functions as a current collector for the generated electricity.
At the fuel electrode (anode) of the fuel cell, hydrogen supplied from the gas flow path and the gas diffusion layer is protonated by the catalytic action of the catalyst layer, passes through the electrolyte membrane, and moves to the oxidizing agent electrode (cathode). The simultaneously generated electrons work through an external circuit and move to the cathode. Oxygen supplied to the cathode reacts with protons and electrons on the cathode to produce water.
The generated water gives an appropriate humidity to the electrolyte membrane, and the excess water permeates the gas diffusion layer and is discharged to the outside of the system.

Various studies have been conducted on fuel cells used in vehicles of fuel cell vehicles (hereinafter sometimes referred to as vehicles).
For example, Patent Document 1 discloses a technique for detecting deterioration of an electrolyte membrane (increase in the amount of cross leak) during power generation of a fuel cell.

In Patent Document 2, among the resistance values of the equivalent circuit of the fuel cell calculated by the arithmetic unit, the amount of electrical short circuit is determined by the magnitude of the film resistance component, and the amount of gas leak is determined by the magnitude of the anode reaction resistance. Described and disclosed.

International Publication No. 2014/115431 Japanese Unexamined Patent Publication No. 2005-0441715

There is a demand for a technique for detecting an increase in the amount of cross leak in a short time during power generation of a fuel cell. In Patent Document 1, the electrolyte membrane is swelled by sufficiently humidifying it to close the holes in the electrolyte membrane where the cross leak is generated. Therefore, excess water adheres to the fuel cell, which causes an increase in gas diffusion resistance due to the occurrence of flooding at a normal operating temperature, which may cause a deterioration in the performance of the fuel cell. Further, even in the temperature range below the freezing point, the water tends to generate ice, which may contribute to the destruction of the catalyst layer. In addition, since it is necessary to measure the output voltage of the fuel cell many times, it takes time to determine the cross leak.

The present disclosure has been made in view of the above circumstances, and an object of the present invention is to provide a fuel cell system that detects a time until a cross leak occurs during power generation of a fuel cell in a short time.

The fuel cell system of the present disclosure is a fuel cell,
A fuel gas supply unit that supplies fuel gas to the anode of the fuel cell,
Oxidizing agent gas supply unit that supplies oxidizing agent gas to the cathode of the fuel cell,
A humidity control unit that adjusts at least one of the relative humidity of the fuel gas and the relative humidity of the oxidant gas.
A temperature control unit that adjusts the temperature of the fuel cell,
A resistance measuring unit for measuring the proton resistance of the electrolyte membrane of the fuel cell, and
Equipped with a control unit
The control unit determines the time until the proton resistance and cross leak of the electrolyte membrane occur during power generation of the fuel cell at a predetermined temperature of the fuel cell and a predetermined relative humidity of the fuel gas and the oxidant gas. A group of data showing the correlation with
After the start of power generation of the fuel cell, the resistance measuring unit measures the proton resistance of the electrolyte membrane, and then measures the proton resistance.
The control unit is characterized in that the proton resistance obtained by the measurement of the resistance measuring unit is collated with the data group to detect the time until the cross leak occurs.

According to the fuel cell system of the present disclosure, it is possible to detect the time until a cross leak occurs during power generation of a fuel cell in a short time.

FIG. 1 is a schematic configuration diagram showing an example of the fuel cell system of the present disclosure. FIG. 2 is a flowchart showing an example of control performed by the fuel cell system of the present disclosure. FIG. 3 is a diagram showing the proton resistance of each sample when the relative humidity of the hydrogen gas permeated through each sample is changed at 80 ° C. FIG. 4 is a diagram showing the amount of cross leak with respect to the durability time of each sample. FIG. 5 is a diagram showing the correlation between the proton resistance and the time until the cross leak occurs.

The fuel cell system of the present disclosure is a fuel cell,
A fuel gas supply unit that supplies fuel gas to the anode of the fuel cell,
Oxidizing agent gas supply unit that supplies oxidizing agent gas to the cathode of the fuel cell,
A humidity control unit that adjusts at least one of the relative humidity of the fuel gas and the relative humidity of the oxidant gas.
A temperature control unit that adjusts the temperature of the fuel cell,
A resistance measuring unit for measuring the proton resistance of the electrolyte membrane of the fuel cell, and
Equipped with a control unit
The control unit determines the time until the proton resistance and cross leak of the electrolyte membrane occur during power generation of the fuel cell at a predetermined temperature of the fuel cell and a predetermined relative humidity of the fuel gas and the oxidant gas. A group of data showing the correlation with
After the start of power generation of the fuel cell, the resistance measuring unit measures the proton resistance of the electrolyte membrane, and then measures the proton resistance.
The control unit is characterized in that the proton resistance obtained by the measurement of the resistance measuring unit is collated with the data group to detect the time until the cross leak occurs.

The cross leak means a phenomenon in which a reaction gas such as a fuel gas at the fuel electrode and an oxidant gas at the oxidant electrode passes through the electrolyte membrane, and the cross leak amount means the amount of gas passing through the electrolyte membrane. do. In the present disclosure, the state in which the reaction gas in an amount exceeding the reference value passes through the electrolyte membrane is defined as the state in which cross leak occurs, and the state in which the reaction gas in an amount below the reference value passes through the electrolyte membrane is defined as the state in which the cross leak occurs. , It is assumed that no cross leak has occurred.
By substituting the degree of deterioration of the electrolyte membrane with the water content of the electrolyte membrane and measuring the proton resistance of the electrolyte membrane that changes depending on the water content, the present disclosers measure the degree of deterioration of the electrolyte membrane and the time until cross leak occurs. We found that we could predict.
According to the present disclosure, by measuring the proton resistance of the electrolyte membrane at the initial stage of operation of the fuel cell, it is possible to detect the cross leak corresponding to the deterioration of the electrolyte membrane at an early stage.
According to the present disclosure, by measuring the proton resistance of the electrolyte membrane at the time of power generation of the fuel cell under the conditions of the predetermined temperature of the fuel cell and the predetermined relative humidity of the fuel gas and the oxidant gas, the extra in the fuel cell is obtained. It is possible to prevent a large amount of water from remaining, and it is possible to suppress the occurrence of flooding and the occurrence of freezing.

The fuel cell system of the present disclosure includes at least a fuel cell, a fuel gas supply unit, an oxidant gas supply unit, a humidity adjustment unit, a temperature adjustment unit, a resistance measurement unit, and a control unit.

The fuel cell system of the present disclosure is usually mounted and used in a fuel cell vehicle whose drive source is an electric motor (motor).
Further, the fuel cell system of the present disclosure may be mounted on and used in a vehicle that can travel with the electric power of a secondary battery.
The electric motor is not particularly limited, and may be a conventionally known drive motor.

The fuel cell may have only one single cell, or may be a fuel cell stack which is a laminated body in which a plurality of single cells are laminated.
The number of stacked single cells is not particularly limited, and may be, for example, 2 to several hundreds or 2 to 200.
The fuel cell stack may include end plates at both ends of the single cell stacking direction.

A single cell of a fuel cell comprises at least a membrane electrode assembly.
The membrane electrode assembly has an anode-side gas diffusion layer, an anode catalyst layer, an electrolyte membrane, a cathode catalyst layer, and a cathode-side gas diffusion layer in this order.

The cathode (oxidizing agent electrode) includes a cathode catalyst layer and a cathode side gas diffusion layer.
The anode (fuel electrode) includes an anode catalyst layer and an anode-side gas diffusion layer.
The cathode catalyst layer and the anode catalyst layer are collectively referred to as a catalyst layer.
The catalyst layer may include, for example, a catalyst metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, carbon particles having electron conductivity, and the like.
As the catalyst metal, for example, platinum (Pt), an alloy composed of Pt and another metal (for example, a Pt alloy in which cobalt, nickel and the like are mixed) and the like can be used.
The electrolyte may be a fluororesin or the like. As the fluororesin, for example, a Nafion solution or the like may be used.
The catalyst metal is supported on carbon particles, and carbon particles (catalyst particles) carrying the catalyst metal and an electrolyte may be mixed in each catalyst layer.
The carbon particles for supporting the catalyst metal (supporting carbon particles) are, for example, water-repellent carbon particles whose water repellency is enhanced by heat-treating commercially available carbon particles (carbon powder). May be used.

The cathode side gas diffusion layer and the anode side gas diffusion layer are collectively referred to as a gas diffusion layer.
The gas diffusion layer may be a conductive member or the like having gas permeability.
Examples of the conductive member include a carbon porous body such as carbon cloth and carbon paper, a metal mesh, and a metal porous body such as foamed metal.

The electrolyte membrane may be a solid polymer electrolyte membrane. Examples of the solid polymer electrolyte membrane include a fluorine-based electrolyte membrane such as a thin film of perfluorosulfonic acid containing water, a hydrocarbon-based electrolyte membrane, and the like. The electrolyte membrane may be, for example, a Nafion membrane (manufactured by DuPont) or the like.

The single cell may be provided with two separators sandwiching both sides of the membrane electrode assembly, if necessary. One of the two separators is the anode side separator and the other is the cathode side separator. In the present disclosure, the anode-side separator and the cathode-side separator are collectively referred to as a separator.
The separator may have a supply hole and a discharge hole for flowing the reaction gas and the refrigerant in the stacking direction of the single cell. As the refrigerant, for example, a mixed solution of ethylene glycol and water can be used in order to prevent freezing at a low temperature. The reaction gas is a fuel gas or an oxidant gas. The fuel gas may be hydrogen or the like. The oxidant gas may be oxygen, air, dry air or the like.
Examples of the supply hole include a fuel gas supply hole, an oxidant gas supply hole, a refrigerant supply hole, and the like.
Examples of the discharge hole include a fuel gas discharge hole, an oxidant gas discharge hole, a refrigerant discharge hole, and the like.
The separator may have one or more fuel gas supply holes, one or more oxidant gas supply holes, or one or more refrigerant supply holes. It may have one or more fuel gas discharge holes, one or more oxidant gas discharge holes, or one or more refrigerant discharge holes.
The separator may have a reaction gas flow path on the surface in contact with the gas diffusion layer. Further, the separator may have a refrigerant flow path for keeping the temperature of the fuel cell constant on the surface opposite to the surface in contact with the gas diffusion layer.
When the separator is an anode-side separator, it may have one or more fuel gas supply holes, or may have one or more oxidant gas supply holes, and one or more refrigerant supply holes. May have one or more fuel gas discharge holes, may have one or more oxidant gas discharge holes, and may have one or more refrigerant discharge holes. The anode-side separator may have a fuel gas flow path for flowing fuel gas from the fuel gas supply hole to the fuel gas discharge hole on the surface in contact with the anode-side gas diffusion layer, and the anode-side gas diffusion may be performed. A gas flow path for flowing a gas from the gas supply hole to the gas discharge hole may be provided on the surface opposite to the surface in contact with the layer.
When the separator is a cathode side separator, it may have one or more fuel gas supply holes, or may have one or more oxidant gas supply holes, and one or more refrigerant supply holes. May have one or more fuel gas discharge holes, may have one or more oxidant gas discharge holes, and may have one or more refrigerant discharge holes. The cathode side separator may have an oxidant gas flow path for flowing the oxidant gas from the oxidant gas supply hole to the oxidant gas discharge hole on the surface in contact with the cathode side gas diffusion layer. A refrigerant flow path for flowing a refrigerant from the refrigerant supply hole to the refrigerant discharge hole may be provided on the surface opposite to the surface in contact with the gas diffusion layer on the cathode side.
The separator may be a gas-impermeable conductive member or the like. The conductive member may be, for example, a dense carbon obtained by compressing carbon to make it impermeable to gas, a press-molded metal (for example, iron, aluminum, stainless steel, etc.) plate or the like. Further, the separator may have a current collecting function.

The fuel cell stack may have a manifold such as an inlet manifold in which each supply hole communicates and an outlet manifold in which each discharge hole communicates.
Examples of the inlet manifold include an anode inlet manifold, a cathode inlet manifold, and a refrigerant inlet manifold.
Examples of the outlet manifold include an anode outlet manifold, a cathode outlet manifold, and a refrigerant outlet manifold.

The fuel cell system has a fuel gas supply unit. The fuel gas supply unit supplies fuel gas to the anode of the fuel cell. The fuel gas supply unit may supply fuel gas to each anode of the fuel cell stack.
The fuel gas is a gas mainly containing hydrogen, and may be, for example, hydrogen gas.
Examples of the fuel gas supply unit include a fuel tank and the like, and specific examples thereof include a liquid hydrogen tank and a compressed hydrogen tank.
The fuel gas supply unit is electrically connected to the control unit. The fuel gas supply unit is driven according to a control signal from the control unit. The fuel gas supply unit may be controlled by the control unit at least one selected from the group consisting of the flow rate and pressure of the fuel gas supplied from the fuel gas supply unit to the anode.

The fuel cell system may include a fuel gas supply channel.
The fuel gas supply channel connects the fuel gas supply unit and the anode inlet of the fuel cell. The fuel gas supply channel allows the fuel gas to be supplied from the fuel gas supply unit to the anode of the fuel cell. The fuel gas supply channel allows the fuel gas to be supplied from the fuel gas supply unit to each anode of the fuel cell stack.

The fuel gas supply flow path may be provided with a fuel gas supply valve.
The fuel gas supply valve makes it possible to adjust the flow rate and pressure of the fuel gas supplied to the anode.
The fuel gas supply valve is electrically connected to the control unit, and the control unit controls the opening / closing and opening of the fuel gas supply valve to control the supply flow rate of the fuel gas to the anode and the fuel gas pressure (anode pressure). May be adjusted.

The fuel cell system may include a fuel off-gas discharge channel.
The fuel off gas discharge channel is connected to the anode outlet of the fuel cell. The fuel off gas discharge channel recovers the fuel off gas, which is the fuel gas discharged from the anode of the fuel cell. The fuel off gas discharge channel may recover the fuel off gas discharged from each anode of the fuel cell stack.
The fuel off gas is supplied to the anode during scavenging, the fuel gas that has passed unreacted at the anode, the water content that the generated water generated at the cathode has reached the anode, the corrosive substances generated at the catalyst layer and the electrolyte membrane, and the like. Also contains good oxidant gas and the like.

The fuel off-gas discharge channel may be provided with a fuel-off gas discharge valve.
The fuel off gas discharge valve makes it possible to discharge the fuel off gas to the outside (outside the system). The outside may be the outside of the fuel cell system or the outside of the vehicle.
The fuel off-gas discharge valve may be electrically connected to the control unit, and the opening / closing of the fuel-off gas discharge valve may be controlled by the control unit to adjust the discharge flow rate of the fuel-off gas to the outside. Further, the fuel gas pressure (anode pressure) supplied to the anode may be adjusted by adjusting the opening degree of the fuel off gas discharge valve.

The fuel cell system may include a circulation channel.
The circulation flow path branches from the fuel off gas discharge flow path and connects to the fuel gas supply flow path. The circulation channel makes it possible to return the recovered fuel off gas to the anode as circulating gas. The circulation channel makes it possible to supply the water contained in the recovered fuel off gas to the anode.
The circulation flow path may merge with the fuel gas supply flow path at the confluence with the fuel gas supply flow path.
If necessary, the fuel cell system may include a circulation pump such as a hydrogen pump for adjusting the flow rate of the circulating gas on the circulation flow path, an ejector, and the like.
The circulation pump may be electrically connected to the control unit, and the flow rate of the circulation gas may be adjusted by controlling the on / off of the drive of the circulation pump, the rotation speed, and the like by the control unit.
The ejector may be arranged, for example, at the confluence of the fuel gas supply flow path and the circulation flow path. The ejector supplies a mixed gas containing a fuel gas and a circulating gas to the anode of the fuel cell. The ejector may supply a mixed gas containing the fuel gas and the circulating gas to each anode of the fuel cell stack. As the ejector, a conventionally known ejector can be adopted.

The fuel cell system may include an anode gas-liquid separator.
The anode gas-liquid separator is arranged at the branch point of the fuel off-gas discharge flow path with the circulation flow path, and separates the water contained in the fuel-off gas, which is the fuel gas discharged from the anode outlet, and the fuel gas. Recover and supply at least one of the recovered water and fuel gas to the anode. The anodic gas-liquid separator may be electrically connected to the control unit. The opening / closing and opening degree of the outlet valve of the anode gas-liquid separator may be controlled by the control of the control unit. Thereby, the amount of water supplied to the anode, the flow rate of the fuel gas, and the like may be controlled.

The fuel cell system has an oxidant gas supply unit.
The oxidant gas supply unit supplies the oxidant gas to the cathode of the fuel cell. The oxidant gas supply unit may supply the oxidant gas to each cathode of the fuel cell stack.
The oxidant gas is an oxygen-containing gas, and may be air, dry air, pure oxygen, or the like.
As the oxidant gas supply unit, for example, an air compressor or the like can be used.
The oxidant gas supply unit is electrically connected to the control unit. The oxidant gas supply unit is driven according to a control signal from the control unit. The oxidant gas supply unit may be controlled by the control unit at least one selected from the group consisting of the flow rate and pressure of the oxidant gas supplied from the oxidant gas supply unit to the cathode.

The fuel cell system may include an oxidant gas supply channel.
The oxidant gas supply channel connects the oxidant gas supply unit and the cathode inlet of the fuel cell. The oxidant gas supply channel enables the supply of the oxidant gas from the oxidant gas supply unit to the cathode of the fuel cell. The oxidant gas supply channel may enable the supply of the oxidant gas from the oxidant gas supply unit to each cathode of the fuel cell stack.

The fuel cell system may include an oxidant off-gas discharge channel.
The oxidant off-gas discharge channel is connected to the cathode outlet of the fuel cell. The oxidant off gas discharge channel enables the oxidant off gas, which is the oxidant gas discharged from the cathode of the fuel cell, to be discharged to the outside. The oxidant off-gas discharge channel may allow the oxidant off-gas discharged from each cathode of the fuel cell stack to be discharged to the outside.
An oxidant gas pressure regulating valve may be provided in the oxidant off gas discharge flow path.
The oxidant gas pressure control valve is electrically connected to the control unit, and the oxidant gas pressure control valve is opened by the control unit to discharge the oxidant off gas, which is the reacted oxidant gas, from the oxidant off gas. Discharge from the flow path to the outside. Further, the oxidant gas pressure (cathode pressure) supplied to the cathode may be adjusted by adjusting the opening degree of the oxidant gas pressure adjusting valve.

Further, the fuel gas supply flow path and the oxidant gas supply flow path may be connected via a confluence flow path. A scavenging valve may be provided in the merging flow path.
The scavenging valve is electrically connected to the control unit, and the scavenging valve is opened by the control unit so that the oxidant gas in the oxidant gas supply unit flows into the fuel gas supply flow path as scavenging gas. It may be.
The scavenging gas used for scavenging may be a fuel gas, an oxidant gas, or a mixed reaction gas containing both of these gases.

The fuel cell system may include a refrigerant supply unit or a refrigerant circulation flow path as a cooling system for the fuel cell.
The refrigerant circulation flow path communicates with the refrigerant supply hole and the refrigerant discharge hole provided in the fuel cell, and enables the refrigerant supplied from the refrigerant supply unit to be circulated inside and outside the fuel cell.
The refrigerant supply unit is electrically connected to the control unit. The refrigerant supply unit is driven according to a control signal from the control unit. The refrigerant supply unit controls the flow rate of the refrigerant supplied from the refrigerant supply unit to the fuel cell by the control unit. Thereby, the temperature of the fuel cell may be controlled.
Examples of the refrigerant supply unit include a cooling water pump and the like.
The refrigerant circulation flow path may be provided with a radiator that dissipates heat from the cooling water.
As the cooling water (refrigerant), for example, a mixed solution of ethylene glycol and water can be used in order to prevent freezing at a low temperature.

The fuel cell system may include a secondary battery.
The secondary battery (battery) may be any as long as it can be charged and discharged, and examples thereof include a nickel hydrogen secondary battery and a conventionally known secondary battery such as a lithium ion secondary battery. Further, the secondary battery may include a power storage element such as an electric double layer capacitor. The secondary battery may have a configuration in which a plurality of secondary batteries are connected in series. The secondary battery supplies electric power to the motor, the oxidant gas supply unit, and the like. The secondary battery may be rechargeable from a power source external to the vehicle, such as a household power source. The secondary battery may be charged by the output of the fuel cell. The charging / discharging of the secondary battery may be controlled by the control unit.

The fuel cell system includes a humidity control unit.
The humidity control unit adjusts at least one of the relative humidity of the fuel gas and the relative humidity of the oxidant gas.
The humidity control unit may be electrically connected to the control unit and driven according to a control signal from the control unit.
The humidity control unit may be, for example, a humidifier or the like.
The humidifier is connected to the fuel gas supply channel and is connected to either the oxidant gas supply channel or the oxidant off gas discharge channel. When the humidifier is connected to the fuel gas supply channel and the oxidant gas supply channel, the humidifier recovers the water contained in the oxidant gas supplied to the cathode inlet and supplies the recovered water to the fuel gas supply channel. do. This adjusts the relative humidity of the fuel gas and the relative humidity of the oxidant gas. When the humidifier is connected to the fuel gas supply flow path and the oxidant off gas discharge flow path, the humidifier recovers the generated water contained in the oxidant off gas, which is the oxidant gas discharged from the cathode outlet, and collects the recovered generated water. Supply to the fuel gas supply channel. This adjusts the relative humidity of the fuel gas.
The fuel cell system may include a humidity sensor that measures the relative humidity of the fuel gas and the oxidant gas. The humidity sensor is electrically connected to the control unit and gives the measured relative humidity to the control unit. The control unit may control the drive of the humidity control unit based on the relative humidity measured by the humidity sensor. The humidity sensor comprises, for example, a dew point meter.

The fuel cell system includes a temperature control unit.
The temperature control unit adjusts the temperature of the fuel cell.
The temperature adjusting unit may be electrically connected to the refrigerant supply unit, and the refrigerant supply unit may control the temperature of the fuel cell by being driven according to a control signal from the temperature adjusting unit.
Therefore, the control unit may also have the function of the temperature adjustment unit.
The fuel cell system may include a temperature sensor that measures the temperature of the fuel cell. The temperature sensor is electrically connected to the control unit and gives the measured temperature to the control unit. The control unit may control the drive of the temperature control unit based on the temperature measured by the temperature sensor.

The resistance measuring unit measures the proton resistance of the electrolyte membrane of the fuel cell.
The resistance measuring unit may be electrically connected to the control unit, and the resistance measuring unit may be driven according to a control signal from the control unit to measure the proton resistance of the electrolyte membrane of the fuel cell. The resistance measuring unit gives the measured proton resistance to the control unit. The control unit may also have the function of the resistance measurement unit.
The method for measuring the proton resistance is not particularly limited, and may be, for example, a proton pump method, a high frequency impedance method, or the like.
The timing at which the resistance measuring unit measures the proton resistance of the electrolyte membrane of the fuel cell is not particularly limited as long as it is after the start of power generation of the fuel cell, but from the viewpoint of detecting the time until the cross leak occurs in a short time, the fuel cell It may be immediately after the start of.

The fuel cell system includes a control unit.
The control unit is a data showing the correlation between the proton resistance of the electrolyte membrane during power generation of the fuel cell and the time until cross leak occurs at a predetermined temperature of the fuel cell and a predetermined relative humidity of the fuel gas and the oxidant gas. Memorize the group in advance.
The predetermined temperature may be, for example, 0 to 30 ° C.
The predetermined relative humidity may be, for example, 15-30%. The predetermined relative humidity of the fuel gas and the predetermined relative humidity of the oxidant gas may be different or the same, but may be the same from the viewpoint of accurately measuring the proton resistance. May be the correlation equation (1) or the like shown in FIG. 5, which will be described later.
The control unit collates the proton resistance obtained by the measurement of the resistance measurement unit with the data group, and detects the time until the cross leak occurs.
The control unit physically includes, for example, an arithmetic processing unit such as a CPU (central processing unit), a ROM (read-only memory) that stores a control program processed by the CPU, control data, and the like, and mainly controls. It has a storage device such as a RAM (random access memory) used as various work areas for processing, and an input / output interface. Further, the control unit may be, for example, a control device such as an ECU (electronic control unit).
The control unit may be electrically connected to an ignition switch which may be mounted on the vehicle. The control unit may be operable by an external power source even if the ignition switch is turned off.

FIG. 1 is a schematic configuration diagram showing an example of the fuel cell system of the present disclosure.
The fuel cell system 100 shown in FIG. 1 includes a fuel cell 10, a fuel gas supply unit 20, a fuel gas supply flow path 21, a fuel off gas discharge flow path 22, an oxidant gas supply unit 30, and an oxidant gas supply. It includes a flow path 31, an oxidant off-gas discharge flow path 32, a humidity adjustment unit 40, a control unit 50, a resistance measurement unit 60, a temperature adjustment unit 70, a fuel filler supply unit 80, and a fuel filler circulation flow path 81.
The humidity adjusting unit 40 is arranged on the fuel gas supply flow path 21 and on the oxidant gas supply flow path 31. The humidity control unit 40 recovers the water contained in the oxidant gas flowing through the oxidant gas supply flow path 31, and supplies the recovered water to the fuel gas flowing through the fuel gas supply flow path 21 to the fuel cell. The relative humidity of the supplied oxidant gas and fuel gas may be adjusted.
The control unit 50 is electrically connected to the humidity adjustment unit 40 and controls the relative humidity of the fuel gas and the oxidant gas by controlling the humidity adjustment unit 40.
The resistance measuring unit 60 is electrically connected to the fuel cell 10 and the control unit 50, and measures the proton resistance of the electrolyte membrane of the fuel cell 10 according to the control signal from the control unit 50.
The temperature adjusting unit 70 is electrically connected to the refrigerant supply unit 80, and controls the temperature of the fuel cell by controlling the refrigerant supply unit 80.

FIG. 2 is a flowchart showing an example of control performed by the fuel cell system of the present disclosure.
As a prerequisite for control, for example, the correlation equation (1) shown in FIG. 5 is incorporated into the fuel cell system as a data group showing the correlation between the proton resistance and the time until the cross leak occurs, and the fuel cell is started in the fuel cell system. The proton resistance in the initial state is stored in advance.
Start the fuel cell.
The temperature control unit adjusts the temperature of the fuel cell to a predetermined temperature (for example, 30 ° C.), and the humidity control unit adjusts the relative humidity of the fuel gas and the oxidant gas to a predetermined relative humidity (for example, 15 to 30% RH). The resistance measuring unit measures the proton resistance of the electrolyte membrane at the initial stage of starting the fuel cell. This makes it possible to suppress the occurrence of flooding and freezing by measuring the proton resistance under low temperature and low relative humidity conditions.
The control unit predicts the time from the measured proton resistance to the occurrence of cross leak using the correlation equation (1). Then, the control unit determines whether or not the time until the cross leak occurs is equal to or longer than the allowable time. If the time until the cross leak occurs is longer than the allowable time, the control unit determines that there is no problem, the temperature adjustment unit raises the temperature of the fuel cell to the normal operating temperature, and the humidity adjustment unit raises the fuel gas and oxidizing agent. Adjust the relative humidity of the gas and operate normally.
If the time until the cross leak occurs is less than the allowable time, the control unit determines that there is a problem and tells the driver of the vehicle that the cell needs to be replaced, for example, if the fuel cell system is mounted on the vehicle. Notify by turning on the warning lamp. The permissible time is not particularly limited, but for example, the time required for the driver to drive the vehicle to the store for cell exchange may be appropriately set.
By the above method, it is possible to easily inform the user such as the driver of the time until the cross leak occurs or the presence or absence of the cross leak in a short time before the cross leak of the electrolyte membrane occurs.

(Reference example)
Hereinafter, verification was performed using the electrolyte membrane samples 1 to 3 in Table 1. In Table 1, it is shown by the standard value when the sample 1 is set as the reference "1".

The proton resistance of each sample in Table 1 was confirmed under the same measurement conditions. The results are shown in FIG.
FIG. 3 is a diagram showing the proton resistance of each sample when the relative humidity of the hydrogen gas permeated through each sample is changed at 80 ° C.
It was found that the proton resistance increased in the order of sample 1, sample 2, and sample 3.
As shown in Table 1 and FIG. 3, it was clarified that the water content correlates with the proton resistance. Protons propagate through the water in the electrolyte membrane, which is a reasonable result.

Next, the durability performance (time until cross leak occurs) was confirmed.
FIG. 4 is a diagram showing the amount of cross leak with respect to the durability time of each sample.
As a result of confirming the time until the cross leak occurs, as shown in FIG. 4, since the cross leak is generated from the electrolyte membrane having a low water content, the time until the cross leak occurs has a correlation with the water content of the electrolyte membrane. It turned out that there was.
When hydroxyl radicals that decompose the electrolyte membrane are generated, in the case of an electrolyte membrane with a low water content, it becomes difficult for the water in the electrolyte membrane to flush away the hydroxyl radicals using the water generated during power generation, and the hydroxyl radicals stay there, causing cross leaks. It can be inferred that it will lead to.

From the above, it is considered that the time until the cross leak occurs correlates with the magnitude of the proton resistance. Therefore, it is possible to grasp the occurrence of cross leak by confirming the proton resistance. In particular, since it is possible to confirm the occurrence of cross leak from the proton resistance of the electrolyte membrane during power generation of the fuel cell in the low relative humidity range, it is possible to easily generate cross leak without humidifying the gas more than necessary. It becomes possible to grasp the time of.

Assuming that the electrolyte membrane decomposes as a result of the deterioration of the electrolyte membrane, and as a result, the water content decreases (proton resistance increases), the electrolyte membranes in Table 1 are the same in the order of sample 1, sample 2, and sample 3. It can be considered to be equivalent to the case where a kind of electrolyte membrane changes with time (deterioration progresses). Based on this, from the results of FIGS. 3 and 4, the correlation between the proton resistance and the time until the cross leak occurred was confirmed.
FIG. 5 is a diagram showing the correlation between the proton resistance and the time until the cross leak occurs.
FIG. 5 shows changes in proton resistance and time until cross leak (gas cross leak) occurs when deterioration progresses in the same electrolyte membrane.
The correlation equation (1) was obtained from each data in FIG.
y = -1.457x + 2.4765 ... (1)
In the formula (1), x indicates the proton resistance and y indicates the time until the cross leak occurs.
From the formula (1), it can be seen that as the proton resistance increases, the time until the cross leak occurs in the electrolyte membrane becomes shorter.
Such a correlation equation can be established for each fuel cell system and used for determining the presence or absence of cross leak. Further, when the allowable time until the cross leak occurs is less than the allowable time, it is possible to notify the driver that the fuel cell should be replaced.

10 Fuel cell 20 Fuel gas supply section 21 Fuel gas supply channel 22 Fuel off gas discharge channel 30 Oxidizing agent gas supply section 31 Oxidizing agent gas supply channel 32 Oxidizing agent off gas discharge channel 40 Humidity control section 50 Control section 60 Resistance measurement Unit 70 Temperature control unit 80 Fuel supply unit 81 Fuel circulation flow path 100 Fuel cell system

Claims (1)

Fuel cell,
A fuel gas supply unit that supplies fuel gas to the anode of the fuel cell,
Oxidizing agent gas supply unit that supplies oxidizing agent gas to the cathode of the fuel cell,
A humidity control unit that adjusts at least one of the relative humidity of the fuel gas and the relative humidity of the oxidant gas.
A temperature control unit that adjusts the temperature of the fuel cell,
A resistance measuring unit for measuring the proton resistance of the electrolyte membrane of the fuel cell, and
Equipped with a control unit
The control unit determines the time until the proton resistance and cross leak of the electrolyte membrane occur during power generation of the fuel cell at a predetermined temperature of the fuel cell and a predetermined relative humidity of the fuel gas and the oxidant gas. A group of data showing the correlation with
After the start of power generation of the fuel cell, the resistance measuring unit measures the proton resistance of the electrolyte membrane, and then measures the proton resistance.
The fuel cell system is characterized in that the control unit collates the proton resistance obtained by the measurement of the resistance measuring unit with the data group and detects the time until a cross leak occurs.

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