JP2023167066A - fuel cell system - Google Patents

Abstract

To provide a fuel cell system which can stabilize output of a fuel cell and also can extend a lifespan thereof.SOLUTION: There is provided a fuel cell system in which a data storage unit stores a temperature deterioration rate of a catalyst and a humidity deterioration rate of the catalyst, and a control unit raises a temperature of a fuel cell stack when humidity in the fuel cell stack exceeds a predetermined specified value α. The control unit performs scavenging when a temperature deterioration rate at a current temperature in the fuel cell stack is greater than a humidity deterioration rate at current humidity in the fuel cell stack and the current humidity in the fuel cell stack exceeds the predetermined specified value α.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to fuel cell systems.

Fuel cell systems have been studied to improve the performance of fuel cells (FC).
For example, Patent Document 1 discloses a fuel that can suppress the redox reaction on the catalyst layer of the fuel electrode and air electrode due to changes in the operating conditions of the fuel cell, and thereby suppress deterioration caused by platinum aggregation and elution of the catalyst layer. A battery system is disclosed.
Patent Document 2 describes a fuel that can reduce the humidity of hydrogen gas and air using an optimal method that matches the operating conditions of the fuel cell to suppress redox reactions, thereby suppressing deterioration caused by platinum aggregation and elution of the catalyst layer. A battery system is disclosed.

Japanese Patent Application Publication No. 2017-224576 JP2017-224575A

Conventional technology, ``control based on electric power,'' is suitable for operating moving objects with large load fluctuations, such as passenger cars, and stationary FCs with large output fluctuations, but it is suitable for moving objects that are expected to have a longer lifespan. (For example, in commercial vehicles, etc.) and in stationary FCs, voltages exceeding the upper and lower limits accumulate, and fuel cell deterioration progresses.
The main mode of catalyst deterioration in fuel cells is elution/enlargement of active species Pt.
When a fuel cell vehicle starts and stops, or increases output due to acceleration uphill, the potential of the fuel cell is varied up and down, exposing the highly reactive Pt in the catalyst and preventing Pt from flowing out due to highly humid water or generated water. is accelerated by temperature fluctuations. Potential, temperature, and humidity are controllable factors and greatly contribute to the output performance and catalyst deterioration performance of the fuel cell, but conventional technology has not been able to weight them.

The present disclosure has been made in view of the above circumstances, and its main purpose is to provide a fuel cell system that can stabilize the output of a fuel cell and extend its life.

The fuel cell system of the present disclosure includes a fuel cell stack, a temperature sensor, a voltage sensor, a current sensor, a flow rate sensor, a fuel gas system, an oxidant gas system, a cooling system, a data storage unit, a control unit,
The fuel cell stack is a cell stack in which a plurality of single cells are stacked,
The single cell has a membrane electrode gas diffusion layer assembly,
The membrane electrode gas diffusion layer assembly includes a cathode gas diffusion layer, a cathode catalyst layer, an electrolyte membrane, an anode catalyst layer, and an anode gas diffusion layer,
The cathode catalyst layer and the anode catalyst layer include at least one of platinum and a platinum alloy as a catalyst, and an electrolyte having proton conductivity,
The data storage unit stores a temperature deterioration rate of the catalyst and a humidity deterioration rate of the catalyst,
The control unit increases the temperature of the fuel cell stack when the humidity within the fuel cell stack exceeds a predetermined specified value α;
The control unit is configured such that the temperature deterioration rate at the current temperature in the fuel cell stack is greater than the humidity deterioration rate at the current humidity in the fuel cell stack, and It is characterized in that air scavenging is performed when the humidity exceeds the predetermined specified value α.

According to the fuel cell system of the present disclosure, it is possible to stabilize the output of the fuel cell and extend its life.

FIG. 1 is a flowchart illustrating an example of catalyst deterioration suppression control in the fuel cell system of the present disclosure. FIG. 2 is a diagram showing the temperature dependence of the voltage drop rate when potential fluctuation durability evaluation was performed under standard conditions of 90° C. and 82.4% RH (relative humidity). FIG. 3 is a diagram showing the humidity dependence of the voltage drop rate when potential fluctuation durability evaluation was performed under standard conditions of 90° C. and 82.4% RH (relative humidity).

Embodiments according to the present disclosure will be described below. Note that matters other than those specifically mentioned in this specification that are necessary for implementing the present disclosure (for example, the general configuration and manufacturing process of a fuel cell system that do not characterize the present disclosure) are It can be understood as a matter of design by a person skilled in the art based on the prior art in the field. The present disclosure can be implemented based on the content disclosed in this specification and the common general knowledge in the field.
In this specification, "~" indicating a numerical range is used to include the numerical values written before and after it as the lower limit and upper limit.
Furthermore, any combination of upper and lower limits in the numerical range can be adopted.

The fuel cell system of the present disclosure includes a fuel cell stack, a temperature sensor, a voltage sensor, a current sensor, a flow rate sensor, a fuel gas system, an oxidant gas system, a cooling system, a data storage unit, a control unit,
The fuel cell stack is a cell stack in which a plurality of single cells are stacked,
The single cell has a membrane electrode gas diffusion layer assembly,
The membrane electrode gas diffusion layer assembly includes a cathode gas diffusion layer, a cathode catalyst layer, an electrolyte membrane, an anode catalyst layer, and an anode gas diffusion layer,
The cathode catalyst layer and the anode catalyst layer include at least one of platinum and a platinum alloy as a catalyst, and an electrolyte having proton conductivity,
The data storage unit stores a temperature deterioration rate of the catalyst and a humidity deterioration rate of the catalyst,
The control unit increases the temperature of the fuel cell stack when the humidity within the fuel cell stack exceeds a predetermined specified value α;
The control unit is configured such that the temperature deterioration rate at the current temperature in the fuel cell stack is greater than the humidity deterioration rate at the current humidity in the fuel cell stack, and It is characterized in that air scavenging is performed when the humidity exceeds the predetermined specified value α.

The main mode of catalyst deterioration in fuel cells is elution/enlargement of active species Pt. The degree of deterioration is measured by the ECSA (electrochemical specific surface area) of the catalyst, and a decrease in ECSA has a strong correlation with a decrease in output performance. The potential fluctuation durability test is a deterioration test that assumes an increase in the output of the fuel cell due to starting and stopping of a fuel cell vehicle or acceleration uphill.By varying the potential of the fuel cell up and down, the highly reactive Pt in the catalyst is Pt efflux due to exposed, humid water or produced water is accelerated by temperature fluctuations.
According to the present disclosure, potential, temperature, and humidity are controllable factors, and greatly contribute to the output performance of the fuel cell and the deterioration performance of the catalyst. In order to suppress fuel cell output performance and catalyst deterioration (ECSA decrease), this disclosure utilizes the fact that the catalyst deterioration rate due to humidity and temperature is different, and scavenges moisture etc. (fuel cell system We propose a fuel cell system that can optimally distribute the temperature rise of the fuel cell (e.g., drainage to the outside) and temperature rise of the fuel cell.

FIG. 1 is a flowchart illustrating an example of catalyst deterioration suppression control in the fuel cell system of the present disclosure.
(1) Measurement of current humidity The control unit measures the humidity inside the fuel cell stack.
(2) Determining whether the current humidity exceeds the specified value α The control unit determines whether the current humidity exceeds the specified value α.
(3) Temperature increase If the current humidity exceeds the specified value α, the control unit increases the temperature of the fuel cell stack. If the current humidity is below the specified value α, the control unit ends the control.
(4) Determination of whether temperature deterioration rate > humidity deterioration rate is satisfied The control unit determines whether the temperature deterioration rate at the current temperature in the fuel cell stack is higher than the humidity deterioration rate at the current humidity in the fuel cell stack. Determine whether it is large or not.
If the temperature deterioration rate at the current temperature within the fuel cell stack is equal to or lower than the humidity deterioration rate at the current humidity within the fuel cell stack, the control unit further increases the temperature of the fuel cell stack.
(5) Determining whether the current humidity exceeds the specified value α The control unit determines whether the temperature deterioration rate at the current temperature inside the fuel cell stack is greater than the humidity deterioration rate at the current humidity inside the fuel cell stack. If so, the control unit again determines whether the current humidity exceeds the specified value α.
(6) The scavenging control unit determines that the temperature deterioration rate at the current temperature in the fuel cell stack is greater than the humidity deterioration rate at the current humidity in the fuel cell stack, and the current humidity in the fuel cell stack is Scavenging is performed when a predetermined value α is exceeded. If the current humidity is below the specified value α, the control unit ends the control.

In the present disclosure, scavenging refers to draining moisture to the outside of the fuel cell system, and exhausting fuel gas to the outside of the fuel cell system to replace the fuel gas in the fuel gas system with oxidizing gas or nitrogen gas. It means at least one of the following, and mainly means draining water to the outside of the fuel cell system.
Therefore, in the present disclosure, scavenging refers to draining water to the outside of the fuel cell system and exhausting the fuel gas to the outside of the fuel cell system to replace the fuel gas in the fuel gas system with oxidizing gas or nitrogen gas. It may be at least one of replacing water, and in particular, water may be drained to the outside of the fuel cell system.
In the present disclosure, the term "draining moisture to the outside of the fuel cell system" refers to only discharging the fuel gas to the outside of the fuel cell system and replacing the fuel gas in the fuel gas system with oxidizing gas or nitrogen gas. It is sometimes called purge to distinguish it from only performing purge.

In this disclosure, it is possible to more directly suppress catalyst deterioration by utilizing data accumulated in the laboratory and performing "control based on the fuel cell voltage drop rate (catalyst deterioration rate)". Become.
FIG. 2 is a diagram showing the temperature dependence of the voltage drop rate when evaluating potential fluctuation durability under standard conditions of 90° C. and 82.4% RH (relative humidity).
FIG. 3 is a diagram showing the humidity dependence of the voltage drop rate when evaluating potential fluctuation durability under standard conditions of 90° C. and 82.4% RH (relative humidity).
If the criterion is a voltage drop rate of 10%, the temperature will be 96°C, close to the upper limit of 100°C, but the humidity will reach 90%.
From this, the sensitivity of the catalyst to deterioration is greater with respect to humidity. That is, in order to suppress the increase in humidity, deterioration of the catalyst can be suppressed by intentionally controlling the temperature to increase in addition to scavenging.
For example, in FIG. 1, when the temperature becomes 90° C. and 90% RH during operation, the absolute humidity is 376 g/m ³ , and if left as is, the voltage drop rate based on humidity will be 10%.
Therefore, by setting the specified value α to 90% RH and increasing the temperature to 92°C, the relative humidity can be reduced to 83% RH even with the same absolute humidity, and the voltage drop rate will be 8% on both temperature and humidity standards. It becomes possible to suppress it.
By continuing this control until the rate of deterioration of the catalyst due to humidity and the rate of deterioration of the catalyst due to temperature both reach 10%, it is possible to eliminate the instability of the fuel cell output due to scavenging and further extend the life of the fuel cell. .

According to the fuel cell system of the present disclosure, in order to improve the output performance of the fuel cell and suppress deterioration of the catalyst (decrease in ECSA), the deterioration rate of the catalyst due to humidity is different from that due to temperature. The scavenging air and fuel cell temperature rise are optimally distributed. Through the above control, both the catalyst deterioration rate due to humidity and the catalyst deterioration rate due to temperature can be maintained in a low state for a long time, and it is possible to further extend the life of the fuel cell while eliminating instability in the output of the fuel cell due to scavenging air.

In this disclosure, the fuel gas and the oxidant gas are collectively referred to as a reaction gas. The reactive gas supplied to the anode is a fuel gas, and the reactive gas supplied to the cathode is an oxidant gas. The fuel gas is a gas mainly containing hydrogen, and may be hydrogen. The oxidant gas is a gas containing oxygen, and may be oxygen, air, dry air, or the like.

The fuel cell system of the present disclosure includes a fuel cell stack, a temperature sensor, a voltage sensor, a current sensor, a flow rate sensor, a fuel gas system, an oxidant gas system, a cooling system, a data storage unit, and a control unit.
The fuel cell system of the present disclosure may be used by being mounted on a moving body such as a vehicle or a stationary FC. The vehicle may be a fuel cell vehicle or the like. Examples of moving objects other than vehicles include railroads, ships, and aircraft.
Further, the fuel cell system of the present disclosure may be used by being mounted on a moving body such as a vehicle that can run on power from a secondary battery.
A mobile object may be equipped with the fuel cell system of the present disclosure. The moving body may include a drive unit such as a motor, an inverter, a hybrid control system, or the like.
The hybrid control system may be capable of driving the mobile object using both the output of the fuel cell and the electric power of the secondary battery.

The fuel cell system of the present disclosure includes a fuel cell stack.
A fuel cell stack is a cell stack in which a plurality of single cells are stacked.
The number of stacked single cells is not particularly limited, and may be, for example, from 2 to several hundreds.
In this disclosure, both a single cell and a fuel cell stack in which single cells are stacked may be referred to as a fuel cell.

A single fuel cell cell has a membrane electrode gas diffusion layer assembly (MEGA).
The membrane electrode gas diffusion layer assembly includes a cathode gas diffusion layer, a cathode catalyst layer, an electrolyte membrane, an anode catalyst layer, and an anode gas diffusion layer in this order.

The cathode (oxidant 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 includes, for example, a catalyst that promotes an electrochemical reaction, an electrolyte (ionomer) that has proton conductivity, and may further include a carrier that has electron conductivity.
As the catalyst, for example, platinum (Pt) or an alloy of Pt and another metal (for example, a Pt alloy containing cobalt, nickel, etc.) can be used.
The electrolyte may be a fluororesin or the like. As the fluororesin, for example, Nafion solution or the like may be used.
The catalyst is supported on a carrier, and in each catalyst layer, the carrier supporting the catalyst (catalyst-supporting carrier) and the electrolyte may coexist.
Examples of the carrier for supporting the catalyst include carbon materials such as carbon that are generally commercially available.

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 carbon porous bodies such as carbon cloth and carbon paper, and metal porous bodies such as metal mesh and foamed metal.

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

The single cell may be provided with two separators that sandwich both sides of the membrane electrode gas diffusion layer assembly, if necessary. One of the two separators is an anode side separator and the other is a cathode side separator. In this disclosure, the anode side separator and the cathode side separator are collectively referred to as separators.
The separator may have holes such as supply holes and discharge holes for allowing fluids such as reaction gas and cooling fluid to flow in the stacking direction of the unit cells.
Examples of the supply hole include a fuel gas supply hole, an oxidant gas supply hole, a cooling fluid supply hole, and the like.
Examples of the exhaust hole include a fuel gas exhaust hole, an oxidant gas exhaust hole, and a cooling fluid exhaust hole.
The separator may have a reactive gas flow path on the surface in contact with the gas diffusion layer. Further, the separator may have a cooling fluid 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.
The separator may be a gas-impermeable conductive member or the like. Examples of the conductive member include thermosetting resins, thermoplastic resins, resin materials such as resin fibers, carbon powder, and dense carbon made gas impermeable by compressing carbon materials such as carbon fibers. , a press-formed metal (for example, iron, aluminum, stainless steel, etc.) plate, etc. may be used. Further, the separator may have a current collecting function.
The shape of the separator may be a rectangle, a horizontally long hexagon, a horizontally long octagon, a circle, an oblong shape, or the like.

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

The fuel cell may include a gasket between adjacent single cells. The gasket is used as a sealing material to prevent leakage of reaction gas from each reaction gas system.
The gasket may be ethylene propylene diene rubber (EPDM) rubber, silicone rubber, thermoplastic elastomer resin, or the like.

The fuel cell system includes a temperature sensor.
The temperature sensor detects the temperature of the fuel cell stack. The temperature of the fuel cell stack may be the temperature of a cooling fluid near a cooling fluid outlet manifold of the fuel cell stack.
The temperature sensor is electrically connected to the control unit. The control unit detects the temperature of the fuel cell stack obtained by the temperature sensor.
A conventionally known voltmeter or the like can be used as the temperature sensor.

The fuel cell system includes a voltage sensor.
The voltage sensor detects the voltage of the fuel cell stack.
The voltage sensor is electrically connected to the control unit. The control unit detects the voltage of the fuel cell stack acquired by the voltage sensor.
As the voltage sensor, a conventionally known voltmeter or the like can be used.

The fuel cell system includes a current sensor.
The current sensor detects the current in the fuel cell stack.
The current sensor is electrically connected to the control unit. The control unit detects the current of the fuel cell stack acquired by the current sensor.
A conventionally known ammeter or the like can be used as the current sensor.

The fuel cell system includes a flow sensor.
The flow rate sensor detects the flow rate of the oxidant gas and fuel gas flowing into the fuel cell stack.
The flow rate sensor is electrically connected to the control unit. The control unit detects the flow rate of the fuel cell stack obtained by the flow rate sensor.
As the flow rate sensor, a conventionally known flow meter or the like can be used.

The fuel cell system may be equipped with a humidity sensor if necessary.
The humidity sensor detects humidity within the fuel cell stack.
The humidity sensor is electrically connected to the control unit. The control unit detects humidity within the fuel cell stack acquired by the humidity sensor.
As the humidity sensor, a conventionally known hygrometer or the like can be used.

The fuel cell system includes a fuel gas system.
The fuel gas system supplies fuel gas to the fuel cell.
The fuel gas system may include a fuel gas supply section, a fuel gas supply channel, a fuel off-gas discharge channel, a fuel gas circulation channel, and the like.
The fuel gas supply section supplies fuel gas to the anode of the fuel cell.
Examples of the fuel gas supply section include a fuel tank, and specifically, a liquid hydrogen tank, a compressed hydrogen tank, and the like.
The fuel gas supply section is electrically connected to the control section. The fuel gas supply section may control ON/OFF of the supply of fuel gas to the fuel cell by controlling the opening and closing of a main stop valve of the fuel gas supply section according to a control signal from the control section.
The fuel gas supply channel connects the fuel gas supply section and the anode inlet of the fuel cell. The fuel gas supply channel enables the supply of fuel gas to the anode of the fuel cell. The anode inlet may be a fuel gas supply hole, an anode inlet manifold, or the like.
The fuel off-gas exhaust channel connects the anode outlet of the fuel cell and the outside of the fuel cell system. The fuel off-gas exhaust passage may merge with the oxidant off-gas exhaust passage at a predetermined region of the oxidant off-gas exhaust passage. The anode outlet may be a fuel gas exhaust hole, an anode outlet manifold, or the like.
The fuel off-gas discharge channel may include a drainage valve (scavenging valve).
The drain valve may be electrically connected to the control unit, and the control unit may control opening and closing of the drain valve to control the amount of water drained to the outside.
The fuel off-gas may include fuel gas that has passed unreacted at the anode, water generated at the cathode, and water that has reached the anode. The fuel off-gas may contain corrosive substances generated in the catalyst layer, electrolyte membrane, and the like.
The fuel gas circulation flow path branches from the fuel off-gas discharge flow path at the branching point of the fuel off-gas discharge flow path, merges with the fuel gas supply flow path at the confluence of the fuel gas supply flow path, and uses the fuel off-gas as a circulating gas. Allows for circulation within the fuel gas system. A three-way discharge/circulation control valve that can control the flow rate of discharge of the fuel off-gas to the outside and the flow rate of circulation within the fuel gas system may be disposed at a branch part of the fuel off-gas discharge flow path. The discharge circulation control three-way valve is electrically connected to the control unit, and the control unit controls the opening/closing and opening degree of the discharge/circulation control three-way valve, thereby controlling the discharge flow rate of fuel off-gas to the outside and the flow rate within the fuel gas system. The circulating flow rate may be controlled.

The fuel cell system includes an oxidant gas system.
The oxidizing gas system may include an oxidizing gas supply section, an oxidizing gas supply channel, an oxidizing gas discharge channel, an oxidizing gas bypass channel, a bypass valve, and the like. Specifically, the oxidant gas supply channel, the oxidant gas discharge channel, and the oxidant gas bypass channel may be pipes.
The oxidizing gas supply unit supplies oxidizing gas to the fuel cell. Specifically, the oxidizing gas supply section supplies oxidizing gas to the cathode of the fuel cell.
The sealed volume of the oxidant gas system may be 5 times or less the sealed volume of the fuel gas system.

Examples of the oxidizing gas supply unit include an air pump, an air compressor, an air blower, and an air fan.
The oxidizing gas supply section may be arranged upstream of the fuel cell in the oxidizing gas supply channel.
The oxidant gas supply section is electrically connected to the control section. The oxidant gas supply section is driven according to a control signal from the control section. In the oxidant gas supply section, at least one of the flow rate and pressure of the oxidant gas supplied from the oxidant gas supply section to the cathode of the fuel cell may be controlled by the control section.

The oxidizing gas supply channel connects the oxidizing gas supply section and the cathode inlet of the fuel cell.
The oxidant gas supply channel enables the oxidant gas to be supplied from the oxidant gas supply section to the cathode of the fuel cell. The cathode inlet may be an oxidizing gas supply hole, a cathode inlet manifold, or the like.
The oxidizing gas supply channel may be provided with a pressure loss body upstream of the oxidizing gas supply section.
Examples of the pressure loss body include a filter and the like. By providing the pressure loss body, impurities in the oxidizing gas can be reduced, and the durability of the fuel cell can be improved.

The oxidizing gas exhaust channel connects the cathode outlet of the fuel cell and the outside of the fuel cell system. The oxidizing gas discharge channel allows the oxidizing gas discharged from the cathode of the fuel cell to be discharged to the outside of the fuel cell system. The cathode outlet may be an oxidizing gas outlet, a cathode outlet manifold, or the like.
The oxidizing gas discharge channel may include an oxidizing gas pressure regulating valve downstream of the cathode outlet of the fuel cell.
The oxidizing gas pressure regulating valve is electrically connected to the control section, and when the oxidizing gas pressure regulating valve is opened by the control section, the oxidizing gas is discharged from the oxidizing gas discharge channel to the outside. Furthermore, the pressure of the oxidizing gas supplied to the cathode (cathode pressure) may be adjusted by adjusting the opening degree of the oxidizing gas pressure regulating valve.

The oxidizing agent off-gas discharge channel may include a drainage valve (scavenging valve).
The drain valve may be electrically connected to the control unit, and the control unit may control opening and closing of the drain valve to control the amount of water drained to the outside.

The oxidant gas bypass flow path branches from the oxidant gas supply flow path, bypasses the fuel cell, and connects the branch portion of the oxidant gas supply flow path and the confluence portion of the oxidant gas discharge flow path.
A bypass valve is arranged in the oxidant gas bypass flow path.
The bypass valve is electrically connected to the control unit, and when the control unit opens the bypass valve, the fuel cell is bypassed and the oxidant gas is supplied to the fuel cell. The gas can be discharged to the outside from the gas discharge channel.

Further, the fuel gas supply channel and the oxidizing gas supply channel may be connected via a converging channel. A purge valve may be provided in the merging channel.
The purge valve may be electrically connected to the control section, and when the purge valve is opened by the control section, the oxidant gas in the oxidant gas supply section may be caused to flow into the fuel gas supply channel as purge gas.
The purge gas used for purging may be nitrogen gas, oxidant gas, or a mixed gas containing these gases.

The fuel cell system includes a cooling system.
The cooling system regulates the temperature of the fuel cell.
The cooling system includes a cooling fluid supply section, a cooling fluid circulation channel, and the like, and may include a cooling fluid bypass channel, a cooling fluid three-way valve, and the like, as necessary.
As the cooling fluid, for example, a mixed solution of ethylene glycol and water can be used to prevent freezing at low temperatures, and other gases such as nitrogen gas and air may also be used.
The cooling fluid circulation channel communicates with a cooling fluid supply hole and a cooling fluid discharge hole provided in the fuel cell, and enables the cooling fluid supplied from the cooling fluid supply section to circulate inside and outside the fuel cell. Make it.
The cooling fluid supply section is electrically connected to the control section. The cooling fluid supply section is driven according to a control signal from the control section. In the cooling fluid supply section, the flow rate of the cooling fluid supplied from the cooling fluid supply section to the fuel cell is controlled by the control section. This may control the temperature of the fuel cell.
Examples of the cooling fluid supply section include a cooling water pump.
The cooling fluid circulation channel may be provided with a radiator that radiates heat from the cooling fluid.
The cooling fluid circulation channel may be provided with a reserve tank that stores the cooling fluid.

The cooling fluid bypass flow path branches from the cooling fluid flow path via the cooling fluid three-way valve, bypasses the fuel cell, communicates with the cooler, and connects to the cooling fluid flow path downstream of the cooling fluid flow path. It merges with the cooling fluid flow path at the fluid flow path merging section. The cooling fluid bypass flow path allows cooling fluid to be circulated in and out of the cooler.
The cooling fluid bypass flow path may include a heater that heats the cooling fluid.
The three-way cooling fluid valve makes it possible to control the supply of cooling fluid from the cooling fluid channel to the cooling fluid bypass channel. The cooling fluid three-way valve is electrically connected to the control unit. The control unit controls opening and closing of the cooling fluid three-way valve.

The fuel cell system may include a humidifier.
The humidifier may be, for example, a bubbling type humidifier.
The humidifier may be placed in at least one of the oxidant gas system and the fuel gas system.
Further, the humidifier may be disposed across the oxidant gas supply channel and the oxidant off-gas discharge channel. In this case, the humidifier may be equipped with a water-permeable membrane, for example. By arranging the water permeable membrane in the area between the oxidant gas supply channel and the oxidant off gas discharge channel and allowing the oxidant gas and oxidant off gas to flow through the humidifier, the water contained in the oxidant off gas can be removed. Moisture passes through the water-permeable membrane and moves to the oxidizing gas, humidifying the oxidizing gas.

The oxidizing gas system may include a cooler (intercooler) downstream of the oxidizing gas supply section of the oxidizing gas supply channel and upstream of the humidifier.
The cooler may exhibit a cooling function by circulating the cooling fluid of the cooling system inside and outside the cooler.

The fuel cell system may include a battery.
The battery (secondary battery) may be anything that can be charged and discharged, and includes conventionally known secondary batteries such as a nickel-metal hydride secondary battery and a lithium ion secondary battery. Further, the secondary battery may include a power storage element such as an electric double layer capacitor. A plurality of secondary batteries may be connected in series. The secondary battery supplies power to an air compressor and the like. The secondary battery may be rechargeable, for example, from a power source external to a mobile object such as a vehicle, such as a household power source. The secondary battery may be charged by the output of the fuel cell. Charging and discharging of the secondary battery may be controlled by a control unit.

The fuel cell system includes a data storage unit.
The data storage unit stores the temperature deterioration rate of the catalyst and the humidity deterioration rate of the catalyst.
The data storage section can appropriately employ a known storage medium.
The temperature deterioration rate of the catalyst may be a data group as shown in FIG. 2, for example.
The humidity deterioration rate of the catalyst may be a data group as shown in FIG. 3, for example.

The fuel cell system includes a control section.
Physically, the control unit 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 a control unit. 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 electronic control unit (ECU).
The control unit may be electrically connected to an ignition switch that may be mounted on a moving object such as a vehicle. The control unit may be operable by an external power source even when the ignition switch is turned off.

The control unit detects the current humidity within the fuel cell stack from a humidity sensor, humidity calculation data, etc., and determines whether the humidity within the fuel cell stack exceeds a predetermined specified value α.
Humidity measurement may be performed by preparing humidity calculation data, a temperature sensor, a voltage sensor, a current sensor, and a flow rate sensor. The humidity may be determined by creating a data map of the amount of generated water in advance from the temperature, current, voltage, and gas supply amount, and comparing these data to calculate the humidity and use it as humidity calculation data.
Alternatively, a humidity sensor may be placed near the cathode outlet manifold of the fuel cell stack to measure humidity.
As a control mechanism for determination, either the fuel gas system or the oxidant gas system may have a post-determination ON switch, a control mechanism (bubbling type humidifier, etc.), and the like. Both the fuel gas system and the oxidizing gas system may have a post-judgment ON switch and a control mechanism (bubbling type humidifier, etc.).
The determination may be made constantly during operation of the fuel cell, or may be made at regular intervals.

The control unit increases the temperature of the fuel cell stack when the humidity within the fuel cell stack exceeds a predetermined regulation value α. When the humidity within the fuel cell stack is below a predetermined specified value α, the control is terminated.
To increase the temperature, a cooling system including a heater, a cooling fluid, etc. may be used, and a temperature sensor or the like may be placed near the cooling fluid outlet manifold of the fuel cell stack to control the temperature.

The control unit detects the current temperature inside the fuel cell stack from the temperature sensor, detects the current humidity inside the fuel cell stack from the humidity sensor, humidity calculation data, etc., and stores the temperature and humidity in the data storage unit. Compare the temperature deterioration rate of the catalyst and the humidity deterioration rate of the catalyst to determine whether the temperature deterioration rate at the current temperature inside the fuel cell stack is greater than the humidity deterioration rate at the current humidity inside the fuel cell stack. do. If the temperature deterioration rate at the current temperature within the fuel cell stack is less than or equal to the humidity deterioration rate at the current humidity within the fuel cell stack, the control unit further increases the temperature of the fuel cell stack.
The control unit is configured such that the temperature deterioration rate at the current temperature within the fuel cell stack is greater than the humidity deterioration rate at the current humidity within the fuel cell stack, and the current humidity within the fuel cell stack is at a predetermined specified value. Scavenging is performed when α is exceeded. When the humidity within the fuel cell stack is below a predetermined specified value α, the control is terminated.
The data storage unit may store data such as those shown in FIGS. 2 and 3 as the determination data.
For scavenging, a scavenging valve and, if necessary, a flow rate sensor or the like may be placed in the system to control the amount of water discharged.

Claims (1)

Equipped with a fuel cell stack, temperature sensor, voltage sensor, current sensor, flow rate sensor, fuel gas system, oxidant gas system, cooling system, data storage unit, and control unit.
The fuel cell stack is a cell stack in which a plurality of single cells are stacked,
The single cell has a membrane electrode gas diffusion layer assembly,
The membrane electrode gas diffusion layer assembly includes a cathode gas diffusion layer, a cathode catalyst layer, an electrolyte membrane, an anode catalyst layer, and an anode gas diffusion layer,
The cathode catalyst layer and the anode catalyst layer include at least one of platinum and a platinum alloy as a catalyst, and an electrolyte having proton conductivity,
The data storage unit stores a temperature deterioration rate of the catalyst and a humidity deterioration rate of the catalyst,
The control unit increases the temperature of the fuel cell stack when the humidity within the fuel cell stack exceeds a predetermined specified value α;
The control unit is configured such that the temperature deterioration rate at the current temperature in the fuel cell stack is greater than the humidity deterioration rate at the current humidity in the fuel cell stack, and A fuel cell system that performs scavenging when humidity exceeds the predetermined specified value α.