Fuel cell system

Abstract

This fuel cell system is provided with: a first fuel cell stack; a second fuel cell stack; a first cooling system that circulates a refrigerant to the first fuel cell stack; a second cooling system for circulating the refrigerant to the second fuel cell stack; and a heat transfer system for circulating the refrigerant between the first cooling system and the second cooling system and cutting off the refrigerant.

Description

TECHNICAL FIELD

[0001] The present specification discloses a fuel cell system. BACKGROUND

[0002] There are also cases where a fuel cell system is provided with a plurality of fuel cell stacks connected to a battery. For example, at the start of a fuel cell system, one cell stack is sometimes started with power from a battery, and after the start of the one cell stack, the other cell stacks are started (Japanese Patent Application Publication No. 2022-117829).

[0003] In the case of being provided with a plurality of cell stacks, even if the cell stacks are started one after another, there is a tendency for the power consumption for starting to increase due to starting a plurality of cell stacks. This tendency is particularly significant in starting at low temperatures. There are also cases where an increase in power consumption at the time of starting results in a decrease in power efficiency. SUMMARY

[0004] The present specification provides a technology for suppressing an increase in power consumption at the time of starting in a fuel cell system provided with a plurality of cell stacks.

[0005] The technology disclosed in the present specification is embodied as a fuel cell system. The fuel cell system is provided with:

[0006] a first fuel cell stack;

[0007] a second fuel cell stack;

[0008] a first cooling system that circulates a refrigerant to the first fuel cell stack;

[0009] a second cooling system that circulates the refrigerant to the second fuel cell stack; and

[0010] a heat transfer system that enables circulation and cutoff of the refrigerant between the first cooling system and the second cooling system.

[0011] According to the above fuel cell system, at the time of starting of the fuel cell system, when one of the first fuel cell stack and the second fuel cell stack, here for example the first fuel cell stack, generates power and the second fuel cell stack does not generate power, the first fuel cell stack is warmed up along with the power generation of the first fuel cell stack, and the temperature of the refrigerant circulating in the first cooling system is also warmed up. By circulating the refrigerant from the first cooling system to the second cooling system in the heat transfer system, the refrigerant is circulated in the second fuel cell stack and the second fuel cell stack is warmed up. That is, the heat generated in the first fuel cell stack by means of the heat transfer system is utilized in the second fuel cell stack. Therefore, the use of power from the battery, the first fuel cell stack can be suppressed or prevented. As a result, the power consumption for starting the power generation of the plurality of fuel cell stacks can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention are described below with reference to the accompanying drawings, in which like reference numerals represent like elements, wherein:

[0013] Figure 1 This is a diagram showing an overview of the fuel cell system disclosed in this specification.

[0014] Figure 2 This is a diagram showing an example of a flowchart of a process executed when a plurality of fuel cell stacks in a fuel cell system start operating.

[0015] Figure 3 This is a diagram showing another example of a flowchart of a process executed when the operation of a plurality of fuel cell stacks in a fuel cell system is started. DETAILED DESCRIPTION

[0016] One embodiment of the fuel cell system disclosed in this specification may include:

[0017] 1st fuel cell stack;

[0018] 2nd fuel cell stack;

[0019] a first cooling system for circulating a refrigerant toward the first fuel cell stack;

[0020] a second cooling system for circulating the refrigerant toward the second fuel cell stack; and

[0021] The heat transfer system is capable of circulating and shutting off the refrigerant between the first cooling system and the second cooling system.

[0022] Another embodiment of the fuel cell system may further include a control device for controlling power generation of the first fuel cell group and the second fuel cell group.

[0023] The above control device performs:

[0024] a first startup process for performing startup operations for starting power generation by the first fuel cell stack and the second fuel cell stack;

[0025] a determination process of determining, after the first start-up process, which of the first fuel cell group and the second fuel cell group is capable of generating electricity;

[0026] a first power generation process in which one of the first fuel cell group and the second fuel cell group determined to be capable of power generation in the determination process generates power, while the other fuel cell group does not generate power; and

[0027] The temperature raising process raises the temperature of the other fuel cell stack by supplying the refrigerant circulating in the one fuel cell stack to the other fuel cell stack via the heat transfer system.

[0028] The fuel cell stack capable of power generation is determined by the first start-up process and the determination process, power generation is performed in the fuel cell stack capable of power generation, and operation is awaited in the other fuel cell stack incapable of operation. The refrigerant is raised in temperature in the fuel cell stack in which power generation is performed, and the other fuel cell stack is raised in temperature by the refrigerant raised in temperature. Therefore, for example, in the case where the fuel cell stack is started up at the freezing point or the like, the fuel cell stack capable of power generation can be selected to perform power generation, and then the other fuel cell stack incapable of power generation due to freezing or the like is raised in temperature to be thawed. Therefore, power consumption can be suppressed, and the other fuel cell stack can be efficiently started up.

[0029] In the one aspect,

[0030] The first cooling system includes a first radiator,

[0031] The second cooling system includes a second radiator,

[0032] The first power generation process is a process of performing power generation by the one fuel cell stack in a state where the refrigerant does not circulate in a radiator included in the one fuel cell stack,

[0033] The temperature raising process is a process of raising the temperature of the other fuel cell stack in a state where the refrigerant does not circulate in a radiator included in the other fuel cell stack.

[0034] Therefore, since the heat of the refrigerant is not taken away by the first and second radiators, the first fuel cell stack and the second fuel cell stack can be efficiently raised in temperature.

[0035] In the one aspect, a step of executing a second start-up process for starting a start-up operation of the power generation of the other fuel cell stack after the temperature raising process can be included. Therefore, power consumption can be suppressed, and the power generation of the other fuel cell stack can be reliably started.

[0036] Another aspect of the fuel cell system can further include a control device that controls the power generation of the first fuel cell stack and the second fuel cell stack,

[0037] The control device executes:

[0038] a first start-up process for starting a start-up operation of the power generation of one of the first fuel cell stack and the second fuel cell stack, and

[0039] The temperature raising process supplies the refrigerant circulated in one of the fuel cell stacks to the other of the fuel cell stacks to raise the temperature of the other fuel cell stack.

[0040] Thus, for example, even in a case where the possibility of icing of the gas flow path is low, it is possible to reduce the power consumption for raising the plurality of fuel cell stacks to start up.

[0041] In the other aspect described above, the control device can perform a second start-up process after the temperature raising process, the second start-up process performing a start-up operation for starting power generation of the other fuel cell stack. In the other aspect described above, the temperature raising process can be performed with restriction on use of power supplied from a battery included in the fuel cell system.

[0042] Hereinafter, the fuel cell system (hereinafter, also simply referred to as system) 2 disclosed in the present specification will be described in detail with appropriate reference to the accompanying drawings. Figure 1 A summary of the system 2 is shown, Figure 2 A flowchart showing a start-up procedure performed by the control device 100 included in the system 2 is shown.

[0043] The system 2 is not particularly limited, and for example, can be a system applied as a driving power source of a mobile body such as a vehicle, or a stationary power generation device. The kind of fuel cell included in the system 2 is not particularly limited, and for example, from the viewpoint of the operating temperature, it is sometimes meaningful to apply to a solid polymer fuel cell (PEFC).

[0044] Fuel cell stack

[0045] As shown in Figure 1 The system 2 includes fuel cell stacks (hereinafter, also simply referred to as cell stacks) 10, 20, cooling systems 30, 40, a battery 50, a heat transfer system 60, and a control device 100. Note that the number of cell stacks included in the system 2 is not limited to two, and is not particularly limited as long as it is a plurality, and can be appropriately changed as needed.

[0046] The cell stacks 10, 20, the fuel gas systems 12, 22, the oxidant gas systems 14, 24, various sensors, valves, switches, and the like included in the cooling systems 30, 40 are appropriately connected so as to be able to input and output signals to and from the control device 100. The control device 100 is constituted by a so-called computer. The control device 100 includes, for example, a processor and a memory, and is provided so as to be able to execute applications necessary for controlling power generation including start-up of the fuel cell stacks 10, 20 included in the system 2.

[0047] The cell stacks 10, 20 are configured by stacking known cells configured in correspondence with the kind of fuel cell. The cell stacks 10, 20 are electrically connected to the battery 50, and configured to be able to use the electric power supplied from the battery 50, and to be able to supply the electric power emitted by the cell stacks 10, 20 to the battery 50. The cell stacks 10, 20 are each one example of the first fuel cell stack and the second fuel cell stack disclosed in this specification.

[0048] Fuel gas system and oxidant gas system

[0049] The cell stacks 10, 20 each have a fuel gas system 12, 22 that makes a fuel gas such as hydrogen flow, and an oxidant gas system 14, 24 that makes an oxidant gas such as air flow. The fuel gas systems 12, 22 can be connected to the same fuel gas supply source. In addition, the oxidant gas systems 14, 24 can be connected to the same oxidant gas supply source.

[0050] Cooling system

[0051] As shown in FIG. 1, the cell stack 10 has a cooling system 30. The cooling system 30 has a pipe 32 through which a prescribed refrigerant that cools the cell stack 10 flows, and a pump 34 that circulates the refrigerant. The pump 34 and the pipe 32 can be appropriately configured as known. Figure 1

[0052] The cooling system 30 can form a circulation flow path 32a in which the refrigerant is circulated to the cell stack 10 by the pump 34 without passing through the radiator 36. The circulation flow path 32a is configured by a flow path 33a, a flow path 10a of the refrigerant in the cell stack 10, a flow path 33b, and a flow path 33c. The pump 34 is provided on the flow path 33a on the upstream side of the cell stack 10 in a manner that causes the refrigerant to flow toward the cell stack 10.

[0053] The cooling system 30 also forms a circulation flow path 32b in which the refrigerant is circulated to the cell stack 10 via the radiator 36. The circulation flow path 32b is configured by the flow path 33a, 10a, the flow path 33b, 33d, a flow path 36a of the refrigerant in the radiator 36, and a flow path 33e. The flow paths 33d, 33e branch from the circulation flow path 32a. A valve 38 that can form the circulation flow path 32a and the circulation flow path 32b, respectively, is provided at a portion of the flow path 33d that branches from the circulation flow path 32a. The valve 38 is formed to be open in both directions in a manner that can configure a portion of the circulation flow path 32a, and to be open in both directions in a manner that can configure a portion of the circulation flow path 32b.

[0054] In addition, the flow path 33b from which the refrigerant is discharged from the cell stack 10 has valves 66, 68. These valves 66, 68 will be described later. ​

[0055] The cooling system 40 can form a circulation flow path 42a in which the refrigerant is circulated to the battery stack 20 by the pump 44 without passing through the radiator 46. The circulation flow path 42a is constituted by the flow path 43a, a flow path 20a of the refrigerant in the battery stack 20, the flow path 43b, and the flow path 43c. The pump 44 is provided on the flow path 43a on the upstream side of the battery stack 20 in such a manner that the refrigerant flows toward the battery stack 20.

[0056] The cooling system 40 can also form a circulation flow path 42b in which the refrigerant is circulated to the battery stack 20 via the radiator 46. The circulation flow path 42b is constituted by the flow path 43a, 20a, the flow path 43b, a flow path 46a of the refrigerant in the radiator 46, and the flow path 43e. The flow paths 43d, 43e branch from the circulation flow path 42a. A valve 48 capable of forming the circulation flow path 42a and the circulation flow path 42b, respectively, is provided at a portion where the flow path 43d branches from the circulation flow path 42a. The valve 48 is formed so as to be open to both directions in such a manner that it can constitute a portion of the circulation flow path 42a, and so as to be open to both directions in such a manner that it can constitute a portion of the circulation flow path 42b.

[0057] Also, the flow path 43b of the circulation flow path 42a from which the refrigerant is discharged from the battery stack 20 is provided with a communication flow path 64 that branches toward the cooling system 30. A shut-off valve 70 is provided on the downstream side of the communication flow path 64. The communication flow path 64 and the shut-off valve 70 will be described later.

[0058] Heat transfer system

[0059] The heat transfer system 60 is configured to form a circulation flow path 60a as needed between the battery stacks 10, 20, in other words, between the cooling system 30 and the cooling system 40. The circulation flow path 60a can be either open to the flow of the refrigerant or shut off to the flow of the refrigerant. The heat transfer system 60 is provided with the flow paths 43a, 20a, 43b in the cooling system 40, the valves 66, 68, and the shut-off valve 70 in addition to the communication flow paths 62, 64 that communicate between the cooling systems 30, 40.

[0060] The communication flow path 62 is connected to the valve 66 in the cooling system 30 and to a position in the cooling system 40 that is on the downstream side of the pump 44 and on the upstream side of the battery stack 20 in the circulation flow path 42a. The refrigerant flowing in the communication flow path 62 from the valve 66 merges into the flow path 43a of the cooling system 40.

[0061] The communication flow path 64 is connected to the valve 68 on the flow path 33b in the cooling system 30 and to the flow path 43b in the cooling system 40. The communication flow path 64 connects the refrigerant from the cooling system 40 to the circulation flow path 32a via the valve 66 without passing through the pump 44. The refrigerant flowing in the communication flow path 64 merges into the circulation flow path 32a of the cooling system 30 via the valve 68.

[0062] Valve 66 is formed so as to be disposed on flow path 33b, and is opened to both cooling system 30 and valve 68 in a manner capable of forming a part of circulation flow path 32a. In addition, valve 66 is formed so as to be opened to both battery stack 10 and communication flow path 62 in a manner that allows refrigerant discharged from battery stack 10 to flow to communication flow path 62.

[0063] Valve 68 is formed on flow path 33c on the downstream side of valve 66. Valve 68 is formed so as to be opened to both valve 66 side and valve 38 in a manner capable of forming a part of circulation flow path 32a. In addition, valve 68 is formed so as to be opened to both communication flow path 64 side and valve 66 side in a manner that allows refrigerant supplied from communication flow path 64 to join circulation flow path 42a.

[0064] Shut-off valve 70 is disposed on flow path 43b at a position on the downstream side from the branched portion to communication flow path 64. Shut-off valve 70 is formed so as to be opened to both flow path 43b and valve 48 in a manner capable of forming circulation flow path 42a. In addition, shut-off valve 70 is formed so as to cut off the inflow of refrigerant from battery stack 20 to valve 48 and allow it to flow to communication flow path 64.

[0065] According to heat transfer system 60, by opening and closing operations of valves 66, 68, and shut-off valve 70, the flow of refrigerant can be cut off between cooling system 30 and cooling system 40. In addition, according to heat transfer system 60, by another manner of opening and closing operations of these valves 66, 68, 80, a circulation flow path 60a can be newly formed for refrigerant to flow between cooling system 30 and cooling system 40. In circulation flow path 60a, refrigerant flowing in circulation flow path 32a by pump 34 flows to flow path 20a of battery stack 20 via valve 66, communication flow path 62, and flow path 43a. And, refrigerant discharged from flow path 20a flows to flow path 43b and communication flow path 64, and reaches valve 68 to join circulation flow path 32a.

[0066] Next, the startup procedure performed when control device 100 starts power generation at the startup of such system 2 will be described. Among them, the following procedures are mainly performed when system 2 is in a low-temperature environment. For startup in a low-temperature environment, valves 38, 48 are controlled so as to circulate in circulation flow paths 32a, 42a, respectively, without passing through radiators 36, 46, in the cooling systems 30, 40 of battery stacks 10, 20. This is to promote the temperature rise of battery stacks 10, 20 in a manner that refrigerant is not cooled by radiators 36, 46. In addition, valves 66, 68, and shut-off valve 70 are controlled in a manner that refrigerant does not flow to circulation flow path 60a of heat transfer system 60.

[0067] The control device 100 performs a start-up operation for both of the cell stacks 10, 20, which is an operation for starting power generation using electric power supplied from the battery 50 to supply hydrogen and oxygen (S10). The S10 of performing the start-up operation is one example of the first start-up process disclosed in the present specification.

[0068] Next, a determination is made as to whether or not the start-up of the cell stacks 10, 20 is permitted, depending on the state of the cell stacks 10, 20 (S20). For the determination, for example, the flow rate of hydrogen when the cell stacks 10, 20 are attempted to start power generation by starting the supply of oxygen and hydrogen, the power generation voltage, or the like can be determined. For example, in a low-temperature environment at freezing point, sometimes the piping of hydrogen freezes and the hydrogen does not flow, or the voltage reverses, or the like. By the control device 100 detecting such phenomena, the cell stack that cannot be started can be discriminated. Since in the case where the outside air temperature is at freezing point, which cell stack 10, 20 cannot be started due to freezing is difficult to discriminate, such a start-up process and determination process are effective. The S20 of making the determination is one example of the determination process disclosed in the present specification.

[0069] In the S20, in the case where both of the cell stacks 10, 20 can be started, power generation is started directly (S30), and the process ends.

[0070] On the other hand, in the S20, as one example, in the case where the cell stack 10 can be started, but the cell stack 20 cannot be started, for the cell stack 10, power generation is started, and for the cell stack 20, the start-up operation is stopped and waits for power generation (S40). Along with the stop of the start-up operation of the cell stack 20, the control device 100 stops the pump 44, and also closes the shutoff valve 70, and stops the inflow of the refrigerant in the circulation flow path 42a. The S40 of performing the power generation is one example of the first power generation process disclosed in the present specification.

[0071] The cell stack 10 is warmed up by the start of power generation of the cell stack 10. By the warming up of the cell stack 10, the temperature of the refrigerant flowing in the cell stack 10 and the cooling system 30 is also warmed up. In addition, the cell stack 10 can also be heated using electric power supplied from the battery 50 to promote the warming up.

[0072] Next, the control device 100 performs determination as to whether the battery stack 10 is sufficiently warmed up (e.g., whether the warm-up operation is ended) (S50). For example, determination can be performed based on the temperature of the battery stack 10 or the temperature of the refrigerant circulating in the cooling system 30 detected by the control device 100. Also, for example, when the temperature of the battery stack 10 or the like becomes equal to or higher than a predetermined threshold temperature, the control device 100 can determine that the warm-up operation is ended. When the warm-up operation of the battery stack 10 is ended, the temperature of the refrigerant circulating in the circulation flow path 32a of the cooling system 30 in the battery stack 10 also generally exceeds 0°C. During a period in which the warm-up operation of the battery stack 10 is not ended, power generation (warm-up operation) of the battery stack 10 is continuously performed. Further, instead of S50, the battery stack 10 can be continuously operated for a predetermined time.

[0073] When the control device 100 determines that the warm-up operation of the battery stack 10 is ended, the control device 100 performs warming up of the battery stack 20 for which the start-up operation is stopped (S60). The battery stack 20 is warmed up by supplying the refrigerant circulating in the circulation flow path 32a of the cooling system 30 of the battery stack 10 to the cooling system 40 via the heat transfer system 60. That is, heat generated in the battery stack 10 is transferred / utilized for warming up of the battery stack 20. In the warming up process of the battery stack 20, no fuel gas and oxidant gas are supplied. S60 in which the warming up is performed is one example of the warming up process in the present specification.

[0074] The control device 100 forms the circulation flow path 60a of the heat transfer system 60 by opening the valves 66, 68 toward the battery stack 20 side, respectively. The frozen portion of the battery stack 20 is thawed and becomes gas circulation possible by heating the frozen portion of the battery stack 20 by the refrigerant passing through the flow path 20a of the battery stack 20.

[0075] Next, the control device 100 performs determination as to whether the battery stack 20 is sufficiently warmed up, for example, by detecting the temperature of the battery stack 20 or the temperature of the refrigerant circulating in the battery stack 20 (S70). The determination criterion of the warming up is, for example, a temperature at which it is inferred that the frozen portion of the battery stack 20 is thawed and is in a state in which power generation is possible. When the temperature of the battery stack 10 exceeds a predetermined threshold temperature, for example, 0°C, the control device 100 determines that the frozen portion of the battery stack 20 is thawed. The battery stack 20 is supplied with the refrigerant circulating in the battery stack 10 by the heat transfer system 60 until the thawing of the battery stack 20 is ended. Further, instead of S70, the refrigerant can be caused to flow in the circulation flow path 60a for a predetermined time.

[0076] When the control device 100 determines that the thawing of the cell stack 20 is completed, the control device 100 starts the supply of hydrogen and oxygen to the cell stack 20 to perform the startup operation for generating power by the cell stack 20 again (S80), and ends the process. Along with the execution of the startup operation, the control device 100 appropriately ends the circulation of the refrigerant involved in the heat transfer system 60. To stop the heat transfer system 60, the control device 100 operates the valves 66, 68 so that the refrigerant is independently circulated in the circulation flow paths 32a, 42a. The S80 of performing the startup operation again is another example of the 2nd startup process disclosed in the present specification.

[0077] By the above process, for example, when the cell stack 10 is able to start up but the cell stack 20 is iced and unable to start up, the use of electric power for the thawing of the iced portion of the cell stack 20 can be suppressed or avoided. The electric power consumption at the startup of the system 2 can be suppressed. As a result, even at the freezing point, the use of the battery electric power can be suppressed to start up the plurality of cell stacks 10, 20.

[0078] Further, in the above embodiment, the S60 of performing the temperature increase performs the temperature increase to thaw the iced portion of the cell stack 20, but is not limited thereto. The temperature increase can be performed to complete the normal warm-up operation in the cell stack 20.

[0079] Further, in the above embodiment, the heat transfer system 60 that supplies the refrigerant circulated in the cell stack 10 to the cell stack 20 is described, but the circulation flow path of the heat transfer system that supplies the refrigerant circulated in the cell stack 20 to the cell stack 10 can also be constructed.

[0080] Further, in the above embodiment, the control device 100 performs the process of determining the cell stack 20 that is unable to start up, but is not limited thereto. For example, when the outside air temperature of the system 2 is a temperature at which the iced state of the cell stacks 10, 20 is not assumed, only one of the cell stacks 10, 20 among the plurality of cell stacks can be started up, and then the other cell stacks can be temperature-increased and started up. One example of such a startup process of the cell stacks 10, 20 is shown in Figure 3

[0081] As shown in Figure 3 , the control device 100 first performs the startup operation for starting the power generation of the cell stack 10 (S110). The S110 of performing the startup operation for the cell stack 10 is another example of the 1st startup process disclosed in the present specification. The control device 100 does not perform the power generation of the cell stack 20, and performs the power generation of the cell stack 10 (S120). The S120 of performing the power generation of only the cell stack 10 is another example of the 1st power generation process disclosed in the present specification.

[0082] ​Then, the control device 100 determines whether the warm-up of the battery stack 10 is complete ( S130 ). This S130 may be replaced by continuing the operation of the battery stack 10 for a predetermined time.

[0083] If the control device 100 determines that the warm-up operation of the battery stack 10 is complete, it raises the temperature of the battery stack 20 (S140). The control device 100 operates valves 66, 68, and shutoff valve 70 to form a circulation flow path 60a, supplying refrigerant from the cooling system 30 to the cooling system 40 to raise the temperature of the battery stack 20. Raising the temperature of the battery stack 20 in S130 is another example of the temperature increase process disclosed in this specification.

[0084] The control device 100 determines whether the temperature of the battery stack 20 has risen sufficiently (S150). The criterion for this determination is, for example, whether the battery stack 20 has reached the warm-up completion temperature achieved through a normal warm-up operation. Alternatively, S150 can be replaced by continuing to flow the refrigerant through the circulation flow path 60a for a predetermined period of time.

[0085] When the control device 100 determines that the temperature of the battery stack 20 has reached the warm-up completion temperature, it performs a startup operation (S160) to start power generation in the battery stack 20 and terminates the process. S150, which performs the startup operation of the battery stack 20, is another example of the second startup process in this specification.

[0086] Thus, by performing a warm-up operation only on the battery stack 10 and then utilizing the heat from the battery stack 10, the battery stack 20 can be completely warmed up without generating electricity (operating) in the battery stack 20. Even if the outside air temperature of the system 2 is low enough to prevent the battery stacks 10 and 20 from freezing, simultaneous warm-up operations for all of the battery stacks 10 and 20 can be avoided, thus suppressing power consumption and potentially improving power efficiency.

[0087] In addition, Figure 3 In the illustrated process, the power supplied from the battery 50 can also be used during the warm-up operation of the battery stack 10. This allows the warm-up operation of the battery stack 10 to be completed quickly. During the temperature increase of the battery stack 20, the operation can also be performed with the power supplied from the battery 50 limited (suppressed or not used). This further reduces power consumption.

[0088] The above-described specific examples of the technology disclosed in the present specification have been described in detail, but these are merely examples and do not limit the technical solutions. The technology described in the technical solutions includes technologies obtained by various modifications and changes to the above-described specific examples, such as the control method of the fuel cell. The technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the technical solutions at the time of filing. The technologies exemplified in the present specification or the drawings can simultaneously achieve multiple purposes, and achieving one of the purposes itself has technical usefulness.

Claims

1. A fuel cell system, wherein, The fuel cell system includes: a first fuel cell stack; a second fuel cell stack; a first cooling system that circulates a refrigerant to the first fuel cell stack; a second cooling system that circulates the refrigerant to the second fuel cell stack; and a heat transfer system that enables circulation and cutoff of the refrigerant between the first cooling system and the second cooling system.

2. The fuel cell system according to claim 1, wherein a control device that controls power generation of the first fuel cell stack and the second fuel cell stack is further included, the control device performs: a first startup process that performs a startup operation for starting power generation involving the first fuel cell stack and the second fuel cell stack; a determination process that determines, after the startup process, which of the first fuel cell stack and the second fuel cell stack is capable of power generation; a first power generation process that performs power generation by one of the first fuel cell stack and the second fuel cell stack determined as capable of power generation in the determination process, and does not perform power generation in the other fuel cell stack; and a warming process that warms the other fuel cell stack by supplying the refrigerant circulated in the one fuel cell stack to the other fuel cell stack via the heat transfer system.

3. The fuel cell system according to claim 2, wherein the first cooling system includes a first radiator, the second cooling system includes a second radiator, the first power generation process is a process that performs power generation by the one fuel cell stack in a state where the refrigerant is not circulated in one radiator included in the one fuel cell stack, the warming process is a process that warms the other fuel cell stack in a state where the refrigerant is not circulated in the other radiator included in the other fuel cell stack.

4. The fuel cell system according to claim 2 or 3, wherein the control device performs a second startup process that performs a startup operation for starting power generation of the other fuel cell stack after the warming process.

5. The fuel cell system according to claim 1, wherein a control device that controls power generation of the first fuel cell stack and the second fuel cell stack is further included, the control device performs: a first startup process that performs a startup operation for starting operation of one of the first fuel cell stack and the second fuel cell stack; a first power generation process that performs power generation by the one fuel cell stack, and does not perform power generation in the other fuel cell stack; and a warming process that warms the other fuel cell stack by supplying the refrigerant circulated in the one fuel cell stack to the other fuel cell stack.

6. The fuel cell system according to claim 5, wherein the control device performs a second startup process that performs a startup operation for starting power generation of the other fuel cell stack after the warming process. ​ 7. The fuel cell system according to claim 5 or 6, wherein The warming-up process is executed with restriction of use of electric power supplied from a cell possessed by the fuel cell system in the other fuel cell stack.

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