JP2023151802A - fuel cell system - Google Patents

Abstract

To provide a fuel cell system capable of suppressing catalyst deterioration of a fuel cell and deterioration of a system construction component.SOLUTION: In the present disclosure, a fuel cell system comprises: a fuel cell; a first gas supply mechanism that supplies a gas to the fuel cell; and a gas flow amount adjustment device that adjust a flow amount of the gas. By providing the gas flow amount adjustment device including: a first determination part that determined whether there is a request of intermittent operation; a first instruction part that instructs so as to increase the flow amount of the gas to the first gas supply construction in the case where the first determination part determines that there is the request of the intermittent operation; a second determination part that determines whether an electrolyte film is in a drying state after the increase of the flow amount of the gas; and a second determination part that instructs so as to perform the intermittent operation to the first gas supply mechanism in the case where the second determination part determines that the electrolyte film is in the drying state, by providing the fuel cell system, the problem is solved.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to fuel cell systems.

A fuel cell system is a system that generates electricity by supplying anode gas and cathode gas to a fuel cell having a fuel electrode (anode), an electrolyte membrane, and an oxygen electrode (cathode).

From the viewpoint of power generation efficiency of fuel cells, techniques are being considered to properly moisten the electrolyte membrane and prevent excessive drying. For example, Patent Document 1 discloses a fuel cell system that performs processing to increase the flow rate of hydrogen when hydrogen shortage or significant drying of an electrolyte membrane is detected. Moreover, Patent Document 2 discloses a fuel cell system that controls the internal water content of a fuel cell stack when the required output of the fuel cell stack decreases.

Japanese Patent Application Publication No. 2013-134866 JP2014-082082A

It is known that a fuel cell system performs intermittent operation in which power generation by the fuel cell is temporarily stopped during low load operation such as low speed driving or idling of the vehicle. On the other hand, even during intermittent operation, anode gas and cathode gas may be supplied to the fuel cell in order to maintain the voltage of the fuel cell in preparation for transition to normal operation.

Here, if the electrolyte membrane of the fuel cell is wet during intermittent operation, cross leakage of cathode gas and anode gas is likely to occur inside the fuel cell, and the voltage of the fuel cell may drop rapidly. If the voltage drops suddenly, catalysts such as the anode and cathode catalysts may deteriorate, and in order to maintain the dropped voltage at an appropriate voltage, gas supply parts, such as gas valves, will have to operate more often, causing parts damage. may deteriorate. In particular, there is a concern that the longer the period of intermittent operation, the greater the influence on the catalyst and parts.

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 suppress catalyst deterioration of a fuel cell and deterioration of system components.

In order to solve the above problems, the present disclosure includes a fuel cell, a first gas supply mechanism that supplies a gas, which is an anode gas or a cathode gas, to the fuel cell, and a gas supply mechanism that adjusts the flow rate of the gas. A fuel cell system comprising: a flow rate adjustment device, wherein the gas flow rate adjustment device determines whether or not there is a request for intermittent operation; and the first determination section determines whether or not there is a request for intermittent operation. a first instruction unit that instructs the first gas supply mechanism to increase the flow rate of the gas when it is determined that the electrolyte membrane is in a dry state after the increase in the flow rate of the gas; a second determination unit that determines whether or not the electrolyte membrane is in a dry state; and if the second determination unit determines that the electrolyte membrane is in a dry state, instructs the first gas supply mechanism to perform intermittent operation; , a second indicator, and a second indicator.

According to the present disclosure, in order to instruct to increase the flow rate of gas supplied to the fuel cell before performing intermittent operation when there is a request for intermittent operation, the electrolyte membrane of the fuel cell is dried at the start of intermittent operation. can be done. As a result, catalyst deterioration of the fuel cell and deterioration of system components can be suppressed.

The present disclosure has the advantage that it is possible to provide a fuel cell system that can suppress catalyst deterioration of the fuel cell and deterioration of system components.

1 is a schematic diagram illustrating the configuration of a fuel cell system according to the present disclosure. 1 is a schematic cross-sectional view illustrating a fuel cell according to the present disclosure. FIG. 3 is a flow diagram illustrating processing performed by the gas flow rate adjustment device in the present disclosure.

Hereinafter, the fuel cell system according to the present disclosure will be described in detail.
FIG. 1 is a schematic diagram illustrating the configuration of a fuel cell system according to the present disclosure. A fuel cell system 100 shown in FIG. 1 includes a fuel cell 10, a first gas supply mechanism (for example, an anode gas supply mechanism) 20, a second gas supply mechanism (for example, a cathode gas supply mechanism) 30, and a fuel cell 10, and an electronic control unit (ECU) 50 that performs various controls of the fuel cell system. The ECU also functions as a gas flow rate adjustment device in the present disclosure, which will be described later. The fuel cell 10, the first gas supply mechanism 20, the second gas supply mechanism 30, the monitoring unit 40, and the ECU 50 (gas flow rate adjustment device) will be described later.

According to the present disclosure, in order to instruct to increase the flow rate of gas supplied to the fuel cell before performing intermittent operation when there is a request for intermittent operation, the electrolyte membrane of the fuel cell is dried at the start of intermittent operation. can be done. As a result, catalyst deterioration of the fuel cell and deterioration of system components can be suppressed.

1. Fuel Cell FIG. 2 is a schematic cross-sectional view illustrating a fuel cell according to the present disclosure. The fuel cell (single cell) 10 shown in FIG. 2 is a membrane-electrode in which a cathode gas diffusion layer 1, a cathode catalyst layer 2, an electrolyte membrane 3, an anode catalyst layer 4, and an anode gas diffusion layer 5 are laminated in this order. It has a joined body (MEA) 11 and two separators 12 that sandwich the MEA 11. The fuel cell may be a single cell or a laminate in which a plurality of single cells are stacked.

Examples of the electrolyte membrane include fluorine-based electrolyte membranes such as perfluorosulfonic acid membranes and non-fluorine-based electrolyte membranes. Examples of non-fluorine electrolyte membranes include hydrocarbon electrolyte membranes. The thickness of the electrolyte membrane is, for example, 5 μm or more and 100 μm or less.

The cathode catalyst layer and the anode catalyst layer include, for example, a catalyst metal that promotes an electrochemical reaction, a base material that supports the catalyst metal, an electrolyte that has proton conductivity, and carbon particles that have electron conductivity. Examples of the catalyst metal include simple metals such as Pt (platinum) and Ru (ruthenium), and alloys containing Pt. Examples of the electrolyte include fluororesin. Furthermore, examples of the base material and the conductive material include carbon materials such as carbon. The thickness of the cathode catalyst layer and the anode catalyst layer is, for example, 5 μm or more and 100 μm or less, respectively.

The anode side gas diffusion layer and the cathode side gas diffusion layer may be electrically conductive members 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 foam metal. The thicknesses of the anode side gas diffusion layer and the cathode side gas diffusion layer are, for example, 5 μm or more and 100 μm or less, respectively.

The separator may have a gas path on the surface facing the gas diffusion layer (the anode gas diffusion layer and the cathode gas diffusion layer). Examples of the material of the separator include metal materials such as stainless steel and carbon materials such as carbon composite materials. Note that this separator has electronic conductivity and also functions as a current collector for the generated electricity.

2. First Gas Supply Mechanism and Second Gas Supply Mechanism The fuel cell system includes a first gas supply mechanism that supplies gas, which is an anode gas or a cathode gas, to the fuel cell. The gas supplied by the first gas supply mechanism may be an anode gas or a cathode gas. That is, the first gas supply mechanism may be an anode gas supply mechanism that supplies anode gas to the fuel cell, or may be a cathode gas supply mechanism that supplies cathode gas to the fuel cell. The fuel cell system also includes a second gas supply mechanism that supplies the fuel cell with a gas that is an anode gas or a cathode gas and is different from the gas that the first gas supply mechanism supplies. You can. As shown in FIG. 1, when the first gas supply mechanism is an anode gas supply mechanism, the second gas supply mechanism is a cathode gas supply mechanism.

As shown in FIG. 1, the anode gas supply mechanism includes, for example, a gas tank 21 that stores anode gas (for example, hydrogen gas), an injector 22 that injects the anode gas, and a mixed gas containing anode gas and anode off gas as fuel. It has an ejector 23 that supplies the fuel to the battery 10, and a gas-liquid separator 24 that removes moisture from the anode off-gas discharged from the fuel cell 10. Further, the anode gas supply mechanism may include an anode gas flow meter 25 that measures the flow rate of the anode gas supplied to the fuel cell 10. The measurement results of the anode gas flow meter 25 are output to the ECU 50. In addition, as shown in FIG. 1, the anode gas supply mechanism 20 is configured to supply an anode off-gas discharged from the fuel cell 10 to the fuel cell 10 again via a gas-liquid separator 24 and an ejector 23. It may have a circulation path.

As shown in FIG. 1, the cathode gas supply mechanism includes, for example, an air compressor 31 that takes in and discharges cathode gas (for example, air), a humidifier 32 that humidifies cathode gas with moisture contained in cathode off gas, and a humidifier 32 that humidifies cathode gas with moisture contained in cathode off gas. It has a valve 33 for controlling the flow of. Further, the cathode gas supply mechanism may include a cathode gas flow meter 34 that measures the flow rate of cathode gas supplied to the fuel cell 10. The measurement results of the cathode gas flow meter 34 are output to the ECU 50.

3. Monitoring Unit The fuel cell system may include a monitoring unit that monitors the fuel cell. As shown in FIG. 1, the monitoring unit 40 monitors the state of the fuel cell 10 and outputs the monitoring result to the ECU 50. Preferably, the monitoring unit includes, for example, a voltage sensor that measures the voltage (OCV) of the fuel cell and a current sensor that measures the current value of the fuel cell.

4. Gas flow rate adjustment device (1) Configuration of gas flow rate adjustment device The fuel cell system according to the present disclosure includes a gas flow rate adjustment device that adjusts the flow rate of the gas. The gas flow rate adjustment device is configured to increase the flow rate of the gas to dry the electrolyte membrane before intermittent operation is performed when there is a request for intermittent operation.

As described above, the electronic control unit (ECU) also functions as a gas flow rate adjustment device in the present disclosure, and includes a CPU (Central Processing Unit), a memory, and an input/output port for inputting and outputting various signals. . The memory includes, for example, ROM (Read Only Memory), RAM (Random Access Memory), and rewritable nonvolatile memory. Various controls are executed by the CPU executing programs stored in the memory. The various controls performed by the ECU are not limited to processing by software, but can also be processed by dedicated hardware (electronic circuits).

The gas flow rate adjustment device has a first determination section, a first instruction section, a second determination section, and a second instruction section as processing blocks for realizing its functions. Further, the gas flow rate adjustment device may include an acquisition unit that acquires the gas flow rates measured by the anode gas flowmeter and the cathode gas flowmeter.

The first determination unit is configured to determine whether there is a request for intermittent operation. The presence or absence of a request for intermittent operation may be determined based on the efficiency with respect to the output of the fuel cell, for example, as disclosed in Japanese Patent Laid-Open No. 2001-307758. Further, in addition to the output efficiency of the fuel cell as disclosed in Japanese Patent Application Laid-open No. 2006-286479, the necessity of intermittent operation may be determined by reflecting the usage status of the output range of the fuel cell.

The first instruction unit is configured to instruct the first gas supply mechanism to increase the flow rate of the gas when the first determination unit determines that there is a request for intermittent operation. . The first instruction unit is configured to instruct the second gas supply mechanism to increase the flow rate of the gas when the first determination unit determines that there is a request for intermittent operation. may have been done. That is, the gas that increases the flow rate may be only the anode gas, only the cathode gas, or both the anode gas and the cathode gas. When increasing both the anode gas and the cathode gas, the first instruction section instructs both the first gas supply mechanism and the second gas supply mechanism. Note that from the viewpoint of energy efficiency, it is preferable to increase only the flow rate of cathode gas (air). The first instruction unit, for example, issues instructions to component parts of the anode gas supply mechanism such as an injector and ejector in the anode gas supply mechanism, and to component parts of the cathode gas supply mechanism such as an air compressor in the cathode gas supply mechanism. Gas flow rate can be increased. The amount of increase (increase rate) in the gas flow rate is not particularly limited, but is, for example, 1.1 times or more, may be 1.3 times or more, or may be 1.5 times or more. Further, it is preferable to record the amount of increase in the gas flow rate in the memory in advance.

The second determination unit is configured to determine whether the electrolyte membrane is in a dry state after the gas flow rate is increased. For example, the second determination unit may calculate the membrane resistance value of the electrolyte membrane based on the impedance of the fuel cell, and determine whether the electrolyte membrane is dry based on the calculated membrane resistance value. Further, the second determination unit may calculate the amount of generated water from the amount of power generated by the fuel cell, and determine whether or not the electrolyte membrane is dry from the calculated amount of generated water. Further, the second determination unit may determine whether the electrolyte membrane is dry based on the operating temperature of the fuel cell. Furthermore, it may be determined whether or not the electrolyte membrane is dry by combining the determination items described above. It is preferable that each of the above-described determination items be recorded in advance as a map in a memory.

The second instruction section is configured to instruct the gas supply mechanism to perform intermittent operation when the second determination section determines that the electrolyte membrane is in a dry state. The second instruction unit can, for example, instruct the components of the first gas supply mechanism to perform intermittent operation. It is preferable to record the conditions of intermittent operation (for example, the upper limit of gas pressure and the lower limit of gas pressure) in the memory in advance.

(2) Processing performed by the gas flow rate adjustment device FIG. 3 is a flowchart illustrating the processing performed by the gas flow rate adjustment device in the present disclosure. In step S1, it is determined whether there is a request for intermittent operation. If there is a request for intermittent operation, the process proceeds to step S2 and the flow rate of at least one of the cathode gas and the anode gas is increased. If it is determined in step 3 that the electrolyte membrane is in a dry state, an instruction is given to perform intermittent operation in step S4, and the process ends.

Note that the present disclosure is not limited to the above embodiments. The above-mentioned embodiments are illustrative, and any configuration that has substantially the same technical idea as the claims of the present disclosure and provides similar effects is the present invention. within the technical scope of the disclosure.

10...Fuel cell 20...First gas supply mechanism 30...Second gas supply mechanism 40...Monitoring unit 50...ECU
100...Fuel cell system

Claims (1)

fuel cell and
a first gas supply mechanism that supplies gas, which is an anode gas or a cathode gas, to the fuel cell;
A fuel cell system comprising a gas flow rate adjustment device that adjusts the flow rate of the gas,
The gas flow rate adjustment device includes:
a first determination unit that determines whether there is a request for intermittent operation;
a first instruction unit that instructs the first gas supply mechanism to increase the flow rate of the gas when the first determination unit determines that there is a request for intermittent operation;
a second determination unit that determines whether the electrolyte membrane is in a dry state after increasing the flow rate of the gas;
A fuel cell system comprising: a second instruction section that instructs the first gas supply mechanism to perform intermittent operation when the second judgment section determines that the electrolyte membrane is in a dry state.