JP2021174671A - Fuel cell system - Google Patents

Abstract

To provide a fuel cell system which is high in the corrosion resistance of a fuel cell stack in consideration of fuel consumption.SOLUTION: A fuel cell system comprises: a fuel cell stack having a structure in which a plurality of cells each having a membrane-electrode assembly including a perfluorosulfonic acid membrane as an electrolyte membrane are laminated; a fuel gas supply part for supplying a fuel gas to the fuel cell stack; a temperature sensor for detecting a temperature of the fuel cell stack; a voltage sensor for detecting a voltage of the fuel cell stack; a current sensor for detecting a current of the fuel cell stack; an inclination sensor for detecting an angle of inclination of the fuel cell stack; and a control part for controlling the driving of the fuel gas supply part.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a fuel cell system.

A fuel cell (FC) is a fuel cell stack (hereinafter, may be simply referred to as a stack) in which a plurality of single cells (hereinafter, may be referred to as cells) are laminated, and hydrogen (H _{2) as a fuel gas.} ) And oxygen (O ₂ ) as an oxidant gas to extract electrical energy through an electrochemical reaction. In the following, the fuel gas and the oxidant gas may be simply referred to as "reaction gas" or "gas" without particular distinction.
The 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.
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 electrons generated at the same time 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.

A fuel cell system with improved corrosion resistance of the fuel cell stack to acid is desired.
For example, in Patent Document 1, when the pH detecting means determines that the acidity of the liquid water in the fuel cell stack is high, the amount of water in the fuel cell stack is increased to suppress the occurrence of acid corrosion. The technology of doing so is disclosed.
In addition, scavenging is used to discharge the liquid water, but it is necessary to increase the gas flow rate for that purpose. Therefore, scavenging more frequently and for a longer time than necessary is not desirable because it causes deterioration of fuel efficiency.

Further, Patent Document 2 discloses a technique of changing the scavenging time according to the amount of residual water.

Japanese Unexamined Patent Publication No. 2006-040610 Japanese Unexamined Patent Publication No. 2018-139181

When a cross leak occurs due to deterioration of the electrolyte membrane, electrolytic corrosion in the gas manifold accelerates, and a leak occurs between each cell through the manifold.
As the amount of cross leak increases in the electrolyte membrane, the rate of deterioration of the electrolyte membrane increases. Therefore, the amount of the film deterioration product dissolved in the power generation water increases, and the ionic conductivity of the manifold retained water increases. Therefore, it is necessary to strengthen the drainage control of the manifold, but the conventional technique cannot strengthen the drainage, and the balance between the durability of the fuel cell stack and the fuel consumption may not be good.
For example, the technique described in Patent Document 1 is to increase the amount of liquid water to raise the pH when the pH detecting means determines that the acidity of the liquid water in the fuel cell stack is high. Not only the pH of the liquid water, but also the liquid entanglement between cells in the manifold due to the accumulated liquid water, the ionic conductivity of the accumulated liquid water, the stack voltage, and the like are factors of progress. Therefore, even if the amount of liquid water is increased to raise the pH, the possibility of liquid entanglement increases due to the increase in liquid water.
Further, even if the technique described in Patent Document 1 is combined with the technique described in Patent Document 2 to drain the water, it may not be sufficient as a countermeasure against corrosion of the stack member.

This disclosure has been made in view of the above circumstances, and it is possible to achieve both measures against corrosion of the stack member due to acid and reduction of the frequency of scavenging energy, and a fuel cell having high corrosion resistance of the fuel cell stack in consideration of fuel efficiency. The main purpose is to provide a system.

In the present disclosure, a fuel cell stack having a configuration in which a plurality of cells including a membrane electrode assembly including a perfluorosulfonic acid film as an electrolyte membrane are stacked is used.
A fuel gas supply unit that supplies fuel gas to the fuel cell stack,
A temperature sensor that detects the temperature of the fuel cell stack, and
A voltage sensor that detects the voltage of the fuel cell stack and
A current sensor that detects the current of the fuel cell stack, and
An inclination sensor that detects the inclination angle of the fuel cell stack, and
It has a control unit that controls the drive of the fuel gas supply unit, and has.
Step (1) The control unit estimates the amount of cross leak from the voltage drop rate detected by the voltage sensor when the supply of the fuel gas is stopped.
Step (2) The control unit uses the temperature detected by the temperature sensor and the current detected by the current sensor, the temperature of the fuel cell stack measured in advance, the current of the fuel cell stack, and the fuel cell. The amount of liquid water produced in the fuel cell stack was calculated in light of the data group showing the correlation with the amount of liquid water produced in the stack.
Step (3) When the generated liquid water amount is not present, the control unit previously measures the temperature detected by the temperature sensor, the current detected by the current sensor, and the estimated cross leak amount. The amount of film deteriorated accumulated in the electrolyte membrane in light of the data group showing the correlation between the temperature of the fuel cell stack and the current of the fuel cell stack and the amount of film decomposition due to the cross leak of the fuel cell stack. Is calculated, the amount of the deteriorated film is added to the integrated amount of film decomposition, and the process returns to the step (2).
Step (4) When the integrated generated water amount is larger than the threshold value, the control unit determines that the membrane-deteriorating substance has been washed out from the electrolyte membrane, and resets the integrated membrane decomposition amount and the integrated generated water amount. On the other hand, when the integrated amount of generated water is equal to or less than the threshold value, the amount of retained liquid in the manifold of the fuel cell stack is calculated from the calculated amount of produced liquid water and the inclination angle detected by the inclination sensor. ,
Step (5) When the inclination angle is equal to or greater than a predetermined threshold value, the control unit determines that the liquid water has flowed out from the manifold, resets the amount of retained liquid water in the manifold, and returns to the step (2). On the other hand, when the inclination angle is less than a predetermined threshold value, the amount of the produced liquid water is added to the amount of the stagnant liquid water.
Step (6) The control unit determines from the inclination angle and the amount of the stagnant liquid water whether or not the stagnant liquid water can be drained by exhaust gas.
Step (7) When the control unit determines that the drainage is impossible, the process returns to the step (2), while when the control unit determines that the drainage is possible, the amount of the film deteriorated material and the amount of the retained liquid water. And, the ionic conductivity of the stagnant liquid water of the manifold is calculated from
Step (8) When the ionic conductivity is less than the threshold value, the control unit ends the control, while when the ionic conductivity is equal to or higher than the threshold value, the liquid water drainage required gas flow rate is determined from the inclination angle. , And further driving the fuel gas supply unit to supply the calculated liquid water drainage required gas flow rate to the fuel cell stack, and discharging the liquid water from the manifold. Provide a system.

According to the fuel cell system of the present disclosure, it is possible to suppress deterioration of the electrolyte membrane and provide a fuel cell system having high durability of the fuel cell stack.

It is a schematic block diagram which shows an example of the fuel cell system of this disclosure. It is a flowchart which shows an example of the control method of the fuel cell system of this disclosure.

In the present disclosure, a fuel cell stack having a configuration in which a plurality of cells including a membrane electrode assembly including a perfluorosulfonic acid film as an electrolyte membrane are stacked is used.
A fuel gas supply unit that supplies fuel gas to the fuel cell stack,
A temperature sensor that detects the temperature of the fuel cell stack, and
A voltage sensor that detects the voltage of the fuel cell stack and
A current sensor that detects the current of the fuel cell stack, and
An inclination sensor that detects the inclination angle of the fuel cell stack, and
It has a control unit that controls the drive of the fuel gas supply unit, and has.
Step (1) The control unit estimates the amount of cross leak from the voltage drop rate detected by the voltage sensor when the supply of the fuel gas is stopped.
Step (2) The control unit uses the temperature detected by the temperature sensor and the current detected by the current sensor, the temperature of the fuel cell stack measured in advance, the current of the fuel cell stack, and the fuel cell. The amount of liquid water produced in the fuel cell stack was calculated in light of the data group showing the correlation with the amount of liquid water produced in the stack.
Step (3) When the generated liquid water amount is not present, the control unit previously measures the temperature detected by the temperature sensor, the current detected by the current sensor, and the estimated cross leak amount. The amount of film deteriorated accumulated in the electrolyte membrane in light of the data group showing the correlation between the temperature of the fuel cell stack and the current of the fuel cell stack and the amount of film decomposition due to the cross leak of the fuel cell stack. Is calculated, the amount of the deteriorated film is added to the integrated amount of film decomposition, and the process returns to the step (2).
Step (4) When the integrated generated water amount is larger than the threshold value, the control unit determines that the membrane-deteriorating substance has been washed out from the electrolyte membrane, and resets the integrated membrane decomposition amount and the integrated generated water amount. On the other hand, when the integrated amount of generated water is equal to or less than the threshold value, the amount of retained liquid in the manifold of the fuel cell stack is calculated from the calculated amount of produced liquid water and the inclination angle detected by the inclination sensor. ,
Step (5) When the inclination angle is equal to or greater than a predetermined threshold value, the control unit determines that the liquid water has flowed out from the manifold, resets the amount of retained liquid water in the manifold, and returns to the step (2). On the other hand, when the inclination angle is less than a predetermined threshold value, the amount of the produced liquid water is added to the amount of the stagnant liquid water.
Step (6) The control unit determines from the inclination angle and the amount of the stagnant liquid water whether or not the stagnant liquid water can be drained by exhaust gas.
Step (7) When the control unit determines that the drainage is impossible, the process returns to the step (2), while when the control unit determines that the drainage is possible, the amount of the film deteriorated material and the amount of the retained liquid water. And, the ionic conductivity of the stagnant liquid water of the manifold is calculated from
Step (8) When the ionic conductivity is less than the threshold value, the control unit ends the control, while when the ionic conductivity is equal to or higher than the threshold value, the liquid water drainage required gas flow rate is determined from the inclination angle. , And further driving the fuel gas supply unit to supply the calculated liquid water drainage required gas flow rate to the fuel cell stack, and discharging the liquid water from the manifold. Provide a system.

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 stack 11, a fuel gas supply unit 12, a fuel gas supply flow path 13, a fuel off gas discharge flow path 14, a sensor unit 15, a control unit 16, and an oxidizing agent. A gas supply unit 21, an oxidant gas supply flow path 22, and an oxidant gas discharge flow path 23 are provided. The sensor unit 15 includes a temperature sensor, a voltage sensor, a current sensor, and an inclination sensor.

According to the present disclosure, in order to both prevent corrosion of the electrolyte membrane by acid and reduce the frequency of scavenging energy, wastewater control is performed when the following two conditions are satisfied.
1) When liquid water can be drained from the stack inclination angle and the amount of residual water in the manifold.
2) When the ionic conductivity of liquid water estimated from the integrated value of the cross-leakage amount of the electrolyte membrane and the membrane decomposition amount during high-temperature operation of the stack exceeds the threshold value.
Then, when the cross leak of the electrolyte membrane is detected, the ionic conductivity of the liquid water estimated from the integrated value of the cross leak amount and the film decomposition amount during high-temperature operation of the stack exceeds the threshold value, and the stack By controlling the drainage when liquid water can be drained from the inclination angle and the amount of residual water in the manifold, the frequency of drainage is increased, the electrolytic corrosion of the manifold that leads to the leak is suppressed, and other parts due to the cross leak of the electrolyte membrane. Suppresses damage.

The fuel cell system of the present disclosure includes at least a fuel cell stack, a fuel gas supply unit, a temperature sensor, a voltage sensor, a current sensor, an inclination sensor, and a control unit, and usually further includes a fuel gas supply unit. , Fuel gas supply channel, fuel off gas discharge section, oxidant gas supply section, oxidant gas supply channel, oxidant gas discharge channel, cooling water supply section, cooling water circulation channel, etc. Be prepared.

The fuel cell system of the present disclosure is usually mounted on a fuel cell vehicle whose drive source is an electric motor (motor).
The electric motor is not particularly limited, and may be a conventionally known motor.

The fuel cell stack may power the motor.
The fuel cell stack is formed by stacking a plurality of fuel cell cells.
The number of stacked 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 in the stacking direction of the cells.
The fuel cell cell may include at least a membrane electrode assembly containing an oxidant electrode, an electrolyte membrane, and a fuel electrode, and may optionally include two separators sandwiching both sides of the membrane electrode assembly. ..

Examples of the electrolyte membrane include a perfluorosulfonic acid membrane and the like, and a Nafion membrane (manufactured by DuPont) and the like may be used.

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 cooling water flow path for keeping the temperature of the fuel cell stack constant on the surface opposite to the surface in contact with the gas diffusion layer.
The separator may have a supply hole and a discharge hole for flowing the reaction gas and the cooling water in the stacking direction of the single cell.
Examples of the supply hole include a fuel gas supply hole, an oxidant gas supply hole, and a cooling water supply hole.
Examples of the discharge hole include a fuel gas discharge hole, an oxidant gas discharge hole, a cooling water discharge hole, and the like.
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 gas impermeable, a press-molded metal (for example, iron, aluminum, stainless steel, etc.) plate or the like. Further, the separator may have a current collecting function.
stomach.
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 cooling water inlet manifold.
Examples of the outlet manifold include an anode outlet manifold, a cathode outlet manifold, and a cooling water outlet manifold.

The oxidant electrode includes an oxidant electrode catalyst layer and a gas diffusion layer.
The fuel electrode includes a fuel electrode catalyst layer and a gas diffusion layer.
The oxidant electrode catalyst layer and the fuel electrode 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) and an alloy composed of Pt and another metal (for example, a Pt alloy in which cobalt, nickel, etc. are mixed) 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) include, for example, water-repellent carbon particles whose water repellency is enhanced by heat-treating commercially available carbon particles (carbon powder). May be used.

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 fuel off-gas discharge unit is not particularly limited as long as it can exhaust the fuel-off gas discharged from the fuel electrode of the fuel cell stack to the outside of the fuel cell system.
The fuel off gas mainly includes a fuel gas that has passed unreacted at the fuel electrode and a water content that the generated water generated at the oxidant electrode has reached the fuel electrode.
The fuel cell system of the present disclosure may include a fuel off-gas discharge flow path, and may further include a fuel-off gas discharge valve, if necessary.
The fuel off gas discharge valve regulates the fuel off gas discharge flow rate.
The fuel off gas discharge flow path makes it possible to discharge the fuel off gas to the outside.

The temperature sensor is not particularly limited as long as it can detect the temperature of the fuel cell stack, and conventionally known ones can be adopted. The temperature of the fuel cell stack may be a temperature near the cooling water outlet (cooling water outlet manifold, etc.) of the fuel cell stack.
The voltage sensor is not particularly limited as long as it can detect the voltage of the fuel cell stack, and conventionally known ones can be adopted.
The current sensor is not particularly limited as long as it can detect the current of the fuel cell stack, and conventionally known ones can be adopted.
The tilt sensor is not particularly limited as long as it can detect the tilt angle of the fuel cell stack, and conventionally known tilt sensors can be adopted.

The fuel gas supply unit supplies fuel gas to 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 flow path connects the fuel gas supply unit and the fuel cell stack, and enables the fuel gas to be supplied from the fuel gas supply unit to the fuel cell stack.

The fuel cell system of the present disclosure may include a circulation flow path that is branched from the fuel off-gas discharge flow path, recovers the fuel off-gas discharged from the fuel electrode of the fuel cell stack, and returns it to the fuel cell stack as circulating gas. ..
The circulation flow path may be provided with a gas-liquid separator for reducing the water content in the fuel off gas. Then, a drainage flow path branched from the circulation flow path by the gas-liquid separator and a drainage valve may be provided on the drainage flow path.
Moisture separated from the fuel-off gas by the gas-liquid separator may be discharged by opening a drain valve provided in the drainage channel branched from the circulation channel.
On the other hand, the fuel off gas from which the water is separated may be supplied to the fuel cell stack from the circulation flow path in a state containing a small amount of residual mist.

The fuel cell system may include an oxidant gas supply unit, an oxidant gas supply flow path, and an oxidant gas discharge flow path.
The oxidant gas supply unit supplies the oxidant gas to at least the oxidant electrode of the fuel cell stack.
As the oxidant gas supply unit, for example, an air compressor or the like can be used. The air compressor is driven according to a control signal from the control unit, and introduces an oxidant gas into the cathode side (oxidant electrode, cathode inlet manifold, etc.) of the fuel cell.
The oxidant gas supply channel connects the oxidant gas supply unit and the fuel cell stack, and enables the oxidant gas to be supplied from the oxidant gas supply unit to the oxidant electrode of the fuel cell stack.
The oxidant gas is an oxygen-containing gas, and may be air, dry air, pure oxygen, or the like.
The oxidant gas discharge channel allows the oxidant gas to be discharged from the fuel cell stack.

The fuel cell system may include a cooling water supply unit and a cooling water circulation flow path.
The cooling water circulation flow path communicates with the cooling water inlet manifold and the cooling water outlet manifold provided in the fuel cell stack, and circulates the cooling water supplied from the cooling water supply unit inside and outside the fuel cell stack to cool the fuel cell stack. to enable.
Examples of the cooling water supply unit include a cooling water pump and the like.
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 control unit controls the fuel cell system and mainly controls the drive of the fuel gas supply unit.
The control unit may be connected to a temperature sensor, a voltage sensor, a current sensor, an inclination sensor, a fuel gas supply unit, an oxidant gas supply unit, and the like via an input / output interface.
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 control programs and control data processed by the CPU, 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 (engine control unit).

FIG. 2 is a flowchart showing an example of the control method of the fuel cell system of the present disclosure. The present disclosure is not necessarily limited to this typical example.
Specifically, the control of the fuel cell system of the present disclosure may be performed in the following steps (1) to (8).

Step (1) Estimating the amount of cross leak The control unit estimates the amount of cross leak from the voltage drop rate detected by the voltage sensor when the supply of fuel gas is stopped.
The timing for estimating the cross-leakage amount is not particularly limited, and may be performed when the operation of the fuel cell stack is stopped, may be performed after a predetermined time has elapsed from the operation stop, or the cross-leakage amount may be estimated at all times. , The estimated time can be set as appropriate.
As a method of estimating the cross-leakage amount, for example, the cross-leakage amount of the electrolyte membrane may be estimated from the time change of the residual voltage of the stack when the stack is stopped.

Step (2) Calculation of the amount of generated liquid water The control unit uses the temperature detected by the temperature sensor and the current detected by the current sensor as the temperature of the fuel cell stack and the current of the fuel cell stack measured in advance. And the data group showing the correlation with the amount of produced liquid water of the fuel cell stack, the amount of produced liquid water of the fuel cell stack is calculated.

Step (3) Calculation of the amount of deteriorated film When the amount of produced liquid water is not present (that is, the amount of produced liquid water = 0), the control unit has the temperature detected by the temperature sensor and the current detected by the current sensor. The estimated cross-leakage amount is compared with a data group showing the correlation between the pre-measured temperature of the fuel cell stack and the current of the fuel cell stack and the amount of film decomposition due to the cross-leakage of the fuel cell stack. Then, the amount of the film deteriorated substance staying in the electrolyte membrane may be calculated, the amount of the film deteriorated substance may be added to the integrated film decomposition amount, and the process may return to the above step (2). On the other hand, when there is the amount of the product liquid water (that is, the amount of the product liquid water> 0), the amount of the product liquid water is added to the cumulative amount of the product liquid water.

Step (4) Calculation of Retained Liquid Water Amount When the integrated generated water amount is larger than the threshold value, the control unit determines that the membrane-deteriorating substance has been washed out from the electrolyte membrane, and determines the integrated membrane decomposition amount and the integrated amount. When the amount of generated water is reset and the integrated amount of generated water is equal to or less than the threshold value, the amount of retained liquid in the manifold of the fuel cell stack is calculated from the calculated amount of produced liquid water and the tilt angle detected by the tilt sensor. calculate.
For the threshold value of the cumulative generated water amount, for example, a data group showing the correlation between the deterioration rate of the electrolyte membrane and the cumulative generated water amount of the fuel cell stack is prepared in advance in an experiment or the like, and the data group is appropriately selected according to the performance of the fuel cell stack and the like. Can be set.

Step (5) Determining whether or not the inclination angle is less than a predetermined threshold value When the inclination angle is equal to or more than a predetermined threshold value, the control unit determines that the liquid water has flowed out from the manifold, and the retained liquid in the manifold. The amount of water may be reset and the process may return to the above step (2). On the other hand, when the inclination angle is less than a predetermined threshold value, the amount of the produced liquid water is added to the amount of the stagnant liquid water.
For example, the inclination of the manifold is estimated by the inclination angle sensor, and if the angle is positive, the liquid water flows out from the manifold, so that the amount of residual water in the manifold may be reset.
On the other hand, for example, when the manifold angle is negative, the amount of produced liquid water may be added to the amount of retained liquid water in the manifold.
For example, the inclination angle threshold can be appropriately set according to the performance of the fuel cell stack or the like by preparing a data group in which the inclination angle at which the liquid water can flow out from the manifold can be measured in advance in an experiment or the like. ..

Step (6) Determining whether or not drainage is possible The control unit determines whether or not the retained liquid water can be drained by exhaust from the inclination angle and the amount of retained liquid water.
For example, from the manifold angle and the amount of liquid water retained in the manifold, it may be estimated that drainage is possible when the height of the liquid level is higher than the height of the drainage pipe inlet.

Step (7) Calculation of Ion Conductivity of Retained Liquid Water If the control unit determines that drainage is not possible, the control unit may return to the step (2). On the other hand, when it is determined that the drainage is possible, the ionic conductivity of the retained liquid water of the manifold is calculated from the amount of the membrane deteriorated substance and the retained liquid water amount.

Step (8) Determining whether the ionic conductivity is equal to or higher than the threshold value The control unit ends the control when the ionic conductivity is less than the threshold value. On the other hand, when the ionic conductivity is equal to or higher than the threshold value, the liquid water drainage required gas flow rate is calculated from the inclination angle, and the fuel gas supply unit is further driven to obtain the calculated liquid water drainage required gas flow rate. It is supplied to the fuel cell stack, and the liquid water is discharged from the manifold.
For the threshold of ionic conductivity, for example, a data group showing the correlation between the ionic conductivity of the retained liquid water and the deterioration rate of the electrolyte membrane is prepared in advance in an experiment or the like, and the data group is appropriately selected according to the performance of the fuel cell stack and the like. Can be set.

The start time of the second control after the end of the first control is not particularly limited, and may be performed without interruption after the end of the first control, or may be performed at regular intervals, and the fuel cell stack may be started. It may be set as appropriate according to the application.

11 Fuel cell stack 12 Fuel gas supply section 13 Fuel gas supply flow path 14 Fuel off gas discharge flow path 15 Sensor unit 16 Control unit 21 Oxidizing agent gas supply unit 22 Oxidizing agent gas supply flow path 23 Oxidizing agent gas discharge flow path 100 Fuel cell system

Claims (1)

A fuel cell stack having a configuration in which a plurality of cells having a membrane electrode assembly including a perfluorosulfonic acid film as an electrolyte membrane are laminated.
A fuel gas supply unit that supplies fuel gas to the fuel cell stack,
A temperature sensor that detects the temperature of the fuel cell stack, and
A voltage sensor that detects the voltage of the fuel cell stack and
A current sensor that detects the current of the fuel cell stack, and
An inclination sensor that detects the inclination angle of the fuel cell stack, and
It has a control unit that controls the drive of the fuel gas supply unit, and has.
Step (1) The control unit estimates the amount of cross leak from the voltage drop rate detected by the voltage sensor when the supply of the fuel gas is stopped.
Step (2) The control unit uses the temperature detected by the temperature sensor and the current detected by the current sensor, the temperature of the fuel cell stack measured in advance, the current of the fuel cell stack, and the fuel cell. The amount of liquid water produced in the fuel cell stack was calculated in light of the data group showing the correlation with the amount of liquid water produced in the stack.
Step (3) When the generated liquid water amount is not present, the control unit previously measures the temperature detected by the temperature sensor, the current detected by the current sensor, and the estimated cross leak amount. The amount of film deteriorated accumulated in the electrolyte membrane in light of the data group showing the correlation between the temperature of the fuel cell stack and the current of the fuel cell stack and the amount of film decomposition due to the cross leak of the fuel cell stack. Is calculated, the amount of the deteriorated film is added to the integrated amount of film decomposition, and the process returns to the step (2).
Step (4) When the integrated generated water amount is larger than the threshold value, the control unit determines that the membrane-deteriorating substance has been washed out from the electrolyte membrane, and resets the integrated membrane decomposition amount and the integrated generated water amount. On the other hand, when the integrated amount of generated water is equal to or less than the threshold value, the amount of retained liquid in the manifold of the fuel cell stack is calculated from the calculated amount of produced liquid water and the inclination angle detected by the inclination sensor. ,
Step (5) When the inclination angle is equal to or greater than a predetermined threshold value, the control unit determines that the liquid water has flowed out from the manifold, resets the amount of retained liquid water in the manifold, and returns to the step (2). On the other hand, when the inclination angle is less than a predetermined threshold value, the amount of the produced liquid water is added to the amount of the stagnant liquid water.
Step (6) The control unit determines from the inclination angle and the amount of the stagnant liquid water whether or not the stagnant liquid water can be drained by exhaust gas.
Step (7) When the control unit determines that the drainage is impossible, the process returns to the step (2), while when the control unit determines that the drainage is possible, the amount of the film deteriorated material and the amount of the retained liquid water. And, the ionic conductivity of the stagnant liquid water of the manifold is calculated from
Step (8) When the ionic conductivity is less than the threshold value, the control unit ends the control, and when the ionic conductivity is equal to or higher than the threshold value, the control unit determines the required gas flow rate for liquid water drainage from the inclination angle. , And further driving the fuel gas supply unit to supply the calculated liquid water drainage required gas flow rate to the fuel cell stack, and discharging the liquid water from the manifold. system.

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