JP2012109094A - Fuel cell system and operation method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system which reduces the deterioration of energy efficiency in heat sterilization processing of recovered water compared to a conventional fuel cell system, and to provide an operation method of the fuel cell system.SOLUTION: A fuel cell system includes: a fuel cell 1; a coolant passage 11 in which a coolant for cooling the fuel cell 1 flows; a coolant tank 7 storing the coolant; a radiator 12 provided at the coolant passage 11; recovered water tanks (5a, 5b) storing water recovered from exhaust gas of the fuel cell 1; water circulation passages (8a, 8b) in which water circulating between the recovered tanks (5a, 5b) and the coolant tank 7 flows; a pump 10 provided at the water circulation passages (8a, 8b); and a controller 20 which operates the pump 10 during power generation operation, carries out water circulation operation which circulates the water between the recovered tanks (5a, 5b) and the coolant tank 7, and reduces a heat radiation amount in the radiator 12 during the water circulation operation compared to when the water circulation operation is not carried out.

Description

The present invention relates to a fuel cell system including a fuel cell and an operation method thereof.

The fuel cell system includes a fuel cell that generates power by an electrochemical reaction between a hydrogen-rich fuel gas and an oxidant gas. The moisture of the gas discharged in the fuel cell system is usually recovered and stored in a recovered water tank. When fungi grow in this recovered water tank, a clogged or narrowed channel in the water supply path to a cooling water tank or reformer that uses the recovered water occurs, and the required amount of water is supplied. It may not be possible.

  Therefore, conventionally, a fuel cell system that sterilizes the recovered water tank by irradiating it with ultraviolet rays (see, for example, Patent Document 1) has been proposed. In addition, a fuel cell system that sterilizes by blowing ozone generated by an ozone generator into recovered water in a recovered water tank (see, for example, Patent Document 2) has also been proposed. In addition, a fuel cell system that sterilizes by heating the temperature of recovered water in the recovered water tank to a predetermined temperature or higher (see, for example, Patent Document 3) has been proposed.

  The fuel cell system described in Patent Document 3 usually has an operating temperature of only several tens of degrees Celsius, and it is difficult to set the temperature of the recovered water to a predetermined temperature (for example, 70 degrees Celsius) or higher necessary for heat sterilization. The exhaust water at the time of power generation of the fuel cell raises the cooling water at least temporarily to a predetermined temperature (for example, 70 ° C.) or higher, mixes the cooling water and the recovered water, and sterilizes the recovered water by heating.

JP 2002-270211 A JP 2004-103394 A JP 2002-270194 A

  However, in the fuel cell system described in Patent Document 3, since the recovered water having a temperature lower than the temperature of the cooling water is supplied into the cooling water tank during the heat sterilization operation of the recovered water, the cooling water temperature decreases. As a result, the operating temperature of the fuel cell is lowered. When the operating temperature of the fuel cell decreases, the amount of water condensation from at least one of the fuel gas and the oxidant gas flowing in the fuel cell increases, which may cause problems such as gas channel blockage.

  The present invention solves the above-described conventional problems, and provides a fuel cell system and a method for operating the same that suppress the temperature drop of the fuel cell during the heat sterilization treatment of recovered water more than the conventional fuel cell system. Objective.

In order to solve the above-described conventional problems, a fuel cell system of the present invention includes a fuel cell, a cooling water passage through which cooling water for cooling the fuel cell flows, a cooling water tank for storing the cooling water, A radiator provided in the cooling water flow path, a recovered water tank for storing water recovered from the exhaust gas of the fuel cell, a water circulation path through which water circulated between the recovered water tank and the cooling water tank flows, A pump provided in the water circulation path, the pump is operated during a power generation operation, a water circulation operation is performed to circulate water between the recovered water tank and the cooling water tank, and when the water circulation operation is performed A controller that reduces the amount of heat released by the radiator compared to when the water circulation operation is not performed.

  The operation method of the fuel cell system according to the present invention includes a recovery water tank for storing water recovered from the exhaust gas of the fuel cell and a cooling water tank for storing cooling water for cooling the fuel cell during power generation operation of the fuel cell. A step (a) of circulating water, and a step (b) of reducing the amount of heat released from the cooling water in the step (a) as compared with the case where the step (a) is not executed.

According to the fuel cell system and the operation method thereof of the present invention, the reduction in energy efficiency during the heat sterilization treatment of the recovered water is suppressed as compared with the conventional fuel cell system.

1 is a diagram illustrating an example of a schematic configuration of a fuel cell system according to Embodiment 1. FIG. FIG. 3 is a flowchart showing an example of the operation of the fuel cell system according to the first embodiment. FIG. 5 is a flowchart showing an example of the operation of the fuel cell system according to Embodiment 2. FIG. 6 is a flowchart showing an example of the operation of the fuel cell system according to Embodiment 3. FIG. 10 is a control flow diagram of water circulation mode control of the fuel cell system according to Embodiment 4; The figure which shows schematic structure of the fuel cell system of an Example.

(Embodiment 1)
A power generation system according to Embodiment 1 includes a fuel cell, a cooling water passage through which cooling water for cooling the fuel cell flows, a cooling water tank for storing cooling water, a radiator provided in the cooling water passage, a fuel A recovery water tank that stores water recovered from the exhaust gas of the battery, a water circulation path through which water circulates between the recovery water tank and the cooling water tank, a pump provided in the water circulation path, and a pump that operates during power generation operation A controller that circulates water between the recovered water tank and the cooling water tank, and reduces the amount of heat released by the radiator when the water circulation operation is performed compared to when the water circulation operation is not performed. Is provided.

  In the operation method of the fuel cell system according to the first embodiment, during the power generation operation, water is collected between a recovered water tank that stores water recovered from the exhaust gas of the fuel cell and a cooling water tank that stores cooling water for cooling the fuel cell. In step (a), and in step (a), the step (b) reduces the amount of heat released from the cooling water as compared to when step (a) is not executed.

  With this configuration, the reduction in energy efficiency during the heat sterilization treatment of the recovered water is reduced as compared with the conventional fuel cell system.

  The water circulation operation does not have to be executed in the entire period during the power generation operation, and may be executed in at least a part of the period during the power generation operation of the fuel cell system.

  The control for reducing the amount of heat released by the radiator need not be executed during the entire period of the water circulation operation, but may be executed during at least a part of the period during the water circulation operation.

  Next, an example of the fuel cell system of Embodiment 1 will be described.

  FIG. 1 is a diagram illustrating an example of a schematic configuration of the fuel cell system according to the first embodiment.

  As shown in FIG. 1, a fuel cell system 100 includes a fuel cell 1, a fuel gas supplier 2, an oxidant gas supplier 3, a communication path 4, a recovered water tank 5a, a recovered water tank 5b, a condenser 6a, and a condenser. 6b, a cooling water tank 7, a first flow path 8a, a second flow path 8b, a first pump 10, a cooling water flow path 11, a radiator 12, a second pump 13, and a controller 20.

  The fuel cell 1 generates power using fuel gas and oxidant gas. Examples of the fuel cell include a polymer electrolyte fuel cell and a phosphoric acid fuel cell, and any type of fuel cell may be used.

  The fuel gas supplier 2 supplies fuel gas to the fuel cell 1, and a hydrogen tank, a hydrogen generator, and the like are exemplified. The oxidant gas supply device 3 supplies an oxidant gas to the fuel cell 1, and examples thereof include an air blower and an air fan.

  The recovered water tank 5 a is a tank that stores water recovered from the off-oxidant gas discharged from the fuel cell 1. The recovered water tank 5 b is a tank that stores water recovered from the off-fuel gas discharged from the fuel cell 1. The communication path 4 is a flow path that connects the recovered water tank 5a and the recovered water tank 5b. Although the fuel cell system 100 of this example includes both the recovered water tank 5a and the recovered water tank 5b, the fuel cell system 100 may include only one of these.

  The condenser 6a condenses and collects moisture in the off-oxidant gas. The condenser 6b condenses and collects moisture in the off-fuel gas. The cooling water tank 7 is a tank that stores cooling water for cooling the fuel cell 1.

The first water channel 8a is a channel through which water supplied from the recovered water tank 5a to the cooling water tank 7 flows, and the second water channel 8a is water supplied from the cooling water tank 7 to the recovered water tank 5b. It is a flowing channel. The water circulation channel includes a first water channel 8a and a second water channel 8b.
The first pump 10 is a pump that is provided in the first water circulation passage and circulates water between the recovered water tank 5 a and the cooling water tank 7. In this example, it is provided in the first water flow path 8a, but is not limited thereto, and may be provided in the second water flow path 8b.
The cooling water channel 11 is a channel through which the cooling water flows, and the radiator 12 is a device that is provided in the cooling water channel 11 and radiates the cooling water from which the exhaust heat of the fuel cell 1 is recovered. It is possible to control the amount of heat. Examples of the radiator 12 include a cooling fan, a radiator, a heat exchanger for recovering exhaust heat, and the like. The second pump 13 is a pump for flowing the cooling water in the cooling water channel 11.

The controller 20 controls the operation of the first pump 10 and the heat dissipation amount of the radiator 12. The controller 20 only needs to have a control function, and includes an arithmetic processing unit (not shown) and a storage unit (not shown) that stores a control program. Examples of the arithmetic processing unit include an MPU and a CPU. A memory is exemplified as the storage unit. The controller 20 means not only a single controller but also a group of controllers in which a plurality of controllers cooperate to execute control of the fuel cell system.
Next, an example of the operation of the fuel cell system 100 will be described.
FIG. 2 is a flowchart showing an example of the operation of the fuel cell system 100.

  First, during the power generation operation of the fuel cell system 100, the controller 20 starts a water circulation operation (step S201). Specifically, the controller 20 starts the operation of the first pump 10. When the operation of the first pump 10 is started, the water in the recovered water tank 5a is supplied to the cooling water tank 7 via the first flow path 8a, and the water in the cooling water tank 7 passes through the second water flow path 8b. To the recovered water tank 5a. Since the water temperature in the cooling water tank 7 is a temperature (for example, 60 ° C.) higher than the sterilization temperature (for example, 40 ° C.) of at least some mold fungi, the water temperature in the recovered water tank mixed with the cooling water in this step is At least a part of the water becomes the sterilization temperature or higher, and the heat sterilization treatment is performed.

  When the water circulation operation is executed, the controller 20 controls the heat radiation amount from the radiator 12 to be lower than when the water circulation operation is not executed (step S202). Although the specific control method is arbitrary, for example, the temperature of the cooling water that has passed through the radiator 12 is detected by a temperature detector (not shown), and the amount of heat released from the radiator 12 is reduced so that the detected temperature increases. The method of doing is illustrated. As another method, a method of reducing the heat radiation amount from the radiator 12 controlled according to the power generation amount of the fuel cell system 100 is exemplified.

  Here, the controller 20 reduces the amount of heat released from the radiator 12 by reducing the heat dissipation capability of the radiator 12. For example, if the radiator 12 is a heat exchanger for exhaust heat recovery, the controller 20 reduces the heat dissipation capability of the radiator 12 by reducing the flow rate of the heat medium for exhaust heat recovery during the water circulation operation. . As another example, if the radiator 12 includes a cooling fan, the controller 20 reduces the heat dissipation capability of the radiator 12 by reducing the output of the cooling fan.

  By step S202, compared with the conventional fuel cell system, the temperature drop of the cooling water due to the supply of the recovered water to the cooling water tank 7 during the water circulation operation, that is, the temperature drop of the fuel cell 1 is suppressed.

  In the above operation flow, after starting the water circulation operation, the control for decreasing the heat dissipation amount of the cooling water is started, but the start timing of both may be the same or vice versa. Absent. That is, it may be executed in at least a part of the period during the water circulation operation.

  Although not shown in FIG. 2, the heat radiation amount from the radiator 12 may be increased as the water circulation operation is stopped, and control may be performed so as to return to the heat radiation amount when the water circulation operation is not performed. Note that the timing of stopping the water circulation operation and the timing of starting the increase in the amount of heat released from the radiator 12 may be the same or may be combined.

  The stop timing of the water circulation operation is arbitrarily set. As an example, the fuel cell system 100 may be configured to stop the water circulation operation when the elapsed time from the start of the water circulation operation becomes equal to or greater than a preset time threshold value. The time threshold may be set as a time (for example, 2 hours) when the temperature of at least a part of the water in the recovered water tank is equal to or higher than the sterilization temperature. As another example, the fuel cell system 100 may be configured to stop the water circulation operation when the temperature of at least a part of the water in the recovered water tank after starting the water circulation operation is equal to or higher than the sterilization temperature.

(Embodiment 2)
The fuel cell system according to the second embodiment executes the water circulation operation when the controller has elapsed the time after the water circulation operation is stopped to be equal to or greater than the first threshold value.

  With such a configuration, since the heat sterilization treatment is periodically performed, the propagation of bacteria in the recovered water is reduced.

  The fuel cell system of the present embodiment may be configured in the same manner as the fuel cell system of the first embodiment except for the points described above.

  Since the fuel cell system 100 described below is configured in the same manner as the fuel cell system 100 of the first embodiment, the description thereof is omitted.

An example of the operation of the fuel cell system 100 of the present embodiment will be described.
FIG. 3 is a flowchart showing an example of the operation of the fuel cell system 100 of the present embodiment.

  As shown in FIG. 3, the controller 20 calculates the elapsed time since the previous water circulation operation was stopped (step S301). Although the calculation method is arbitrary, for example, the elapsed time is calculated from the current time measured by a timer (not shown) and the stop time of the water circulation operation stored in the storage unit (not shown). Then, it is determined whether or not the calculated elapsed time is equal to or greater than a first threshold (step S302). Here, after the water circulation operation is stopped, the first threshold value is set to a time period during which no channel blockage occurs in the water supply path to the water-using device due to the propagation of fungi in the recovered water, for example, set to 24 hours. The

  If the controller 20 determines that the elapsed time after stopping the water circulation operation is less than the first threshold value (No in step S302), the controller 20 returns to S301 and executes the calculation of the elapsed time again. On the other hand, if the controller 20 determines that the elapsed time after stopping the water circulation operation is equal to or greater than the first threshold (Yes in step 302), if the fuel cell system 100 is in the power generation operation, the water circulation is continued as it is. Operation is executed (step S201). If the fuel cell system 100 is in the stop period, the water circulation operation is executed during the next power generation operation.

  In the water circulation operation, as in the first embodiment, the controller 20 controls the heat radiation amount from the radiator 12 to be lower than when the water circulation operation is not performed (step S202).

  Although not shown in FIG. 3, when the water circulation operation is stopped, the heat radiation amount from the radiator 12 is increased, and the heat radiation amount when the water circulation operation is not performed is controlled. The stop timing of the water circulation operation is arbitrarily set as in the first embodiment.

(Embodiment 3)
In the fuel cell system of the third embodiment, the controller executes the water circulation operation when the accumulated stop time of the fuel cell system after the water circulation operation is stopped becomes equal to or greater than the second threshold value.

  With such a configuration, the heat sterilization process is performed in consideration of the stop time of the fuel cell system in which bacteria are likely to propagate. Therefore, the propagation of bacteria can be further suppressed as compared with the case where the stop time of the system is not considered. .

  The fuel cell system according to the present embodiment may be configured in the same manner as the fuel cell system according to any one of the first and second embodiments except for the points described above.

  Since the fuel cell system 100 described below is configured in the same manner as the fuel cell system 100 of the first embodiment, the description thereof is omitted.

  An example of the operation of the fuel cell system of the present embodiment will be described.

FIG. 4 is a flowchart showing an example of the operation of the fuel cell system 100 of the present embodiment.
As shown in FIG. 4, the controller 20 calculates the cumulative stop time of the fuel cell system 100 since the previous water circulation operation was stopped during the stop period of the fuel cell system 100 (step S401). The calculation method is arbitrary. For example, the current time measured by a timer (not shown), the time when the previous water circulation operation was stored in the storage unit (not shown), the start time of the fuel cell system, and From the stop time of the fuel cell system, the cumulative stop time of the fuel cell system 100 since the water circulation operation was previously stopped is calculated.
Then, it is determined whether or not the calculated accumulated stop time is equal to or greater than a second threshold (step S402). Here, after the water circulation operation is stopped, the second threshold value is set to a time period during which no channel blockage occurs in the water supply path to the water-using device due to the propagation of fungi in the recovered water, for example, 12 hours. The

  Here, the second threshold value is set to be shorter than the first threshold value used in step S302 of the operation flow of the fuel cell system of the first embodiment. This is because during the power generation operation of the fuel cell system, condensed water is supplied to the recovered water tank 5a and water is supplied to the water utilization device (cooling water tank 7 or reformer (not shown)). The water in the recovered water tank 5a is replaced, but the water in the recovered water tank 5a remains stagnant while the fuel cell system 100 is stopped. This is because it is easy to breed.

  When the controller 20 determines that the accumulated stop time of the fuel cell system after stopping the water circulation operation is less than the second threshold (No in step S402), the controller 20 returns to step S401, and the accumulated stop time is Run the calculation again.

On the other hand, if it is determined that the cumulative stop time of the fuel cell system after stopping the water circulation operation is equal to or longer than the second threshold (Yes in step S402), the next fuel cell system starts to be started (step S403), Thereafter, the water circulation operation is executed after the power generation operation of the fuel cell system is started (step S404) (step S201).
In the water circulation operation, as in the first embodiment, the controller 20 controls the heat radiation amount from the radiator 12 to be lower than when the water circulation operation is not performed (step S202).

Although not shown in FIG. 4, when the water circulation operation is stopped, the heat radiation amount from the radiator 12 is increased, and control is performed to return to the heat radiation amount when the water circulation operation is not performed. The stop timing of the water circulation operation is arbitrarily set as in the first embodiment.
(Embodiment 4)
In the fuel cell system according to the fourth embodiment, the controller executes the water circulation operation when the temperature of the cooling water becomes equal to or higher than a predetermined threshold value.

  With this configuration, it is possible to suppress the growth of bacteria compared to the case where the water circulation operation is executed without considering the cooling water temperature.

  Here, the temperature of the cooling water being equal to or higher than the predetermined threshold means that the detection value of the detector that directly or indirectly detects the temperature of the cooling water is equal to or higher than the predetermined threshold. The detector that directly detects the temperature of the cooling water is exemplified by a temperature detector provided in the cooling water tank 7 or the cooling water passage 11. The detector that indirectly detects the temperature of the cooling water is exemplified by a detector that detects an elapsed time after the fuel cell system starts generating power.

  The fuel cell system according to the present embodiment may be configured in the same manner as the fuel cell system according to any one of the first embodiment, the second embodiment, and the third embodiment except for the points described above.

  Since the fuel cell system 100 described below is configured in the same manner as the fuel cell system 100 of the first embodiment, the description thereof is omitted.

  An example of the operation of the fuel cell system of the present embodiment will be described.

FIG. 5 is a flowchart showing an example of the operation of the fuel cell system 100 of the present embodiment.
As shown in FIG. 5, the controller 20 has a fuel cell system when the elapsed time after stopping the water circulation operation is equal to or longer than the first threshold (Yes in step S302), or after stopping the water circulation operation. Is equal to or greater than the second threshold (Yes in step S402), the temperature of the cooling water is detected by a cooling water temperature detector (not shown) during the power generation operation of the fuel cell system (step S501).

  Next, it is determined whether or not the temperature of the cooling water detected by the cooling water temperature detector is equal to or higher than a predetermined threshold (step S502). Here, the predetermined threshold is defined as a temperature higher than the sterilization temperature of at least some fungi included in the collected water.

  When the controller 20 determines that the temperature of the cooling water is lower than the predetermined threshold (No in step S502), the controller 20 returns to step S501 and executes the detection of the cooling water temperature again. On the other hand, when the controller 20 determines that the temperature of the cooling water is equal to or higher than the predetermined threshold (Yes in step S502), the controller 20 executes the water circulation operation as in the first embodiment (step S201), Control to reduce the heat dissipation.

  Even when the fuel cell system is in a power generation operation, the temperature of the cooling water is low, and it may not be sterilized at all. For example, depending on the specifications, the fuel cell system may have a form in which the temperature of the cooling water is low at the beginning of power generation, increases as power generation continues, and stabilizes at a temperature that can be sterilized. Here, as described above, it is confirmed that the temperature of the cooling water is a sterilizable temperature, and the water circulation operation is executed, whereby at least a part of the fungus is recovered by heat sterilization.

  In steps S501 and S502, the temperature of the cooling water is directly detected to determine whether the temperature is sterilizable. However, the present invention is not limited to this. As described above, a mode may be adopted in which it is determined whether or not the parameter for indirectly detecting the temperature of the cooling water is equal to or greater than a predetermined threshold value. For example, the form which determines whether the elapsed time after starting electric power generation of a fuel cell system is more than a predetermined threshold value is mentioned. Here, the predetermined threshold is set as a time for the temperature of the cooling water to reach a sterilizable temperature, for example, 1 hour.

  Although not shown in FIG. 5, when the water circulation operation is stopped, the heat radiation amount from the radiator 12 is increased, and control is performed to return to the heat radiation amount when the water circulation operation is not performed. The stop timing of the water circulation operation is arbitrarily set as in the first embodiment.

[Example]
An example of the fuel cell system according to any of Embodiments 1-4 will be described.

  FIG. 6 is a diagram showing a schematic configuration of the fuel cell system of the present embodiment.

  In FIG. 6, the description of the components denoted by the same reference numerals as those in FIG. 1 in FIG.

  The fuel cell system 100 of the present embodiment includes a heat exchanger 12a, a second pump 13, a heat medium flow path 14, and a heat accumulator 15.

  The heat exchanger 12a is an example of the radiator 12 in FIG. 1, and is a heat exchanger that exchanges heat between the cooling water recovered from the fuel cell 1 and the heat medium. The heat medium flow path 14 is a flow path through which the heat medium flows, and the second pump 13 is a pump provided in the heat medium flow path 14 to flow the heat medium in the heat medium flow path 14. The heat accumulator 15 is a device that stores heat recovered by a heat medium. Examples of the heat medium include water and antifreeze.

  Next, the operation of the fuel cell system 100 of the present embodiment will be described.

  The fuel cell system 100 of the present example performs the water circulation operation in the same manner as any one of the fuel cell systems of Embodiment 1-4. In the water circulation operation, the controller 20 reduces the operation amount of the second pump 13 so that the amount of heat recovered from the heat exchanger 12a is reduced. The operation amount is an input amount for controlling the operation amount of the second pump 13 and includes, for example, a voltage value. The controller 20 reduces the voltage value in step S202 and controls the flow rate of the heat medium flowing through the heat medium flow path 14 to decrease. The voltage value is an example, and the operation amount is not limited to this.

  For example, the operation amount is an input current value for driving the second pump 13, a fluctuation frequency of the input voltage for driving the second pump 13, a duty ratio of the input voltage for driving the second pump 13, and the like. There may be.

  On the other hand, when the water circulation operation is stopped, the controller 20 increases the heat recovery amount from the heat exchanger 12a and controls to return to the heat recovery amount when the water circulation operation is not performed. For example, when the manipulated variable is a voltage value, the controller 20 increases the voltage value and controls the flow rate of the heat medium flowing through the heat medium flow path 14 to decrease. The voltage value is an example, and the operation amount is not limited to this.

  In the fuel cell system 100 of the embodiment 1-4 and the example, the water is circulated between the cooling water of the cooling water tank 7 and the recovered water tank 5a. The water may be circulated between the tank 5b, or the water may be circulated between the cooling water tank 7 and the tank that shares the recovered water tanks 5a and 5b. Good. That is, any configuration may be employed as long as water is circulated between a recovered water tank that stores water recovered from the exhaust gas of the fuel cell and a cooling water tank.

  From the above description, many modifications and other embodiments are apparent to persons skilled in the art. Accordingly, the above description should be construed as illustrative only.

The fuel cell power generation system of the present invention is useful for a fuel cell system used for home use and the like because a decrease in energy efficiency during the heat sterilization treatment of recovered water is suppressed as compared with a conventional fuel cell system.

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Fuel gas supply device 3 Oxidant gas supply device 4 Communication path 5a Recovered water tank 5b Recovered water tank 6a Condenser 6b Condenser 7 Cooling water tank 8a First flow path 8b Second flow path 10 First pump 11 Cooling water channel 12 Radiator 12a Heat exchanger 13 Second pump 14 Heat medium channel 15 Heat accumulator 20 Controller 100 Fuel cell system

Claims (7)

A fuel cell;
A cooling water flow path through which cooling water for cooling the fuel cell flows;
A cooling water tank for storing the cooling water;
A radiator provided in the cooling water flow path;
A recovered water tank for storing water recovered from the exhaust gas of the fuel cell;
A water circulation path through which water circulated between the recovered water tank and the cooling water tank flows;
A pump provided in the water circulation path;
A water circulation operation is performed in which the pump is operated during power generation operation to circulate water between the recovered water tank and the cooling water tank, and the heat dissipation is performed when the water circulation operation is performed compared to when the water circulation operation is not performed. A fuel cell system comprising a controller for reducing the amount of heat released from the vessel. The radiator is a heat exchanger for exchanging heat between the cooling water and the heat medium,
A flow controller for controlling the flow rate of the heat medium passing through the heat exchanger;
2. The fuel according to claim 1, wherein the controller controls the flow rate controller so that the flow rate of the heat medium passing through the heat exchanger is reduced during the water circulation operation compared to when the water circulation operation is not performed. Battery system. 3. The fuel cell system according to claim 1, wherein the controller executes the water circulation operation when an elapsed time after the water circulation operation is stopped becomes equal to or greater than a first threshold value. 4. The fuel according to any one of claims 1 to 3, wherein the controller executes the water circulation operation when an accumulated stop time of the fuel cell system after the water circulation operation is stopped becomes a second threshold value or more. Battery system. The fuel cell system according to any one of claims 1 to 4, wherein the controller executes the water circulation operation when a temperature of the cooling water is equal to or higher than a predetermined threshold value.   The said controller reduces the heat dissipation of the said cooling water at the time of execution of the said water circulation operation from the time of the non-execution of the said water circulation operation according to the water temperature of the said recovery water tank. Fuel cell system. Circulating the water between a recovered water tank for storing water recovered from the exhaust gas of the fuel cell and a cooling water tank for storing cooling water for cooling the fuel cell during power generation operation (a);
A method of operating a fuel cell system, comprising the step (b) of reducing the amount of heat released from the cooling water when executing the step (a) compared to when not executing the step (a).

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