JP2006140005A - Fuel cell cooling system and protection method for fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell cooling system keeping cold performance of a fuel cell stack after gas is mixed to a liquid circulation system of a fuel cell system, and to provide a protection method for the fuel cell system. <P>SOLUTION: The fuel cell cooling system is equipped with a coolant pump 3 for circulating coolant between the fuel cell stack 1 and a radiator 2, a tank 4 storing the coolant, a water level detector 5 detecting or presuming the amount of the coolant, temperature sensors 6a, 6b detecting or presuming the temperature of the coolant, a pressure detector 7 detecting or presuming the pressure of the coolant, and a judgement part 9 judging whether the amount of the coolant is normal or abnormal from the pressure of the coolant detected with the pressure detector 7, the temperature of the coolant detected with the temperature sensors 6a, 6b, and the amount of the coolant detected with the water level detector 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell cooling system and a method for protecting the fuel cell system, and more particularly to a technique for detecting an abnormality occurring in a liquid circulation system in which a refrigerant for cooling a fuel cell stack flows.

  Fuel cell technology is a power source or power source that enables clean exhaust and high energy efficiency against recent environmental problems, especially air pollution caused by automobile exhaust gas and global warming caused by carbon dioxide. Attention has been paid.

  The fuel cell system supplies hydrogen as a fuel or a gas having a high hydrogen concentration, oxygen as an oxidant, or air containing oxygen to a fuel cell stack, which is a composite of an electrolyte and an electrode catalyst. It is an energy conversion system that causes chemical reactions and converts chemical energy into electrical energy. Since a solid polymer electrolyte fuel cell having a particularly high power density among fuel cell systems is generally controlled so that the temperature of the fuel cell stack is 85 ° C. or lower, water is used as the refrigerant. Many.

For example, a protection device for a fuel cell system as shown in FIG. 6 is conventionally known (see, for example, Patent Document 1). A refrigerant pipe 63 connects between the internal refrigerant passage of the fuel cell stack 51 and the radiator 52, and the refrigerant pump 53 circulates the refrigerant. The refrigerant pipe 63 is provided with a flow rate detector 54 that detects the flow rate of the refrigerant pump 53, a pressure detector 57 that detects the discharge pressure of the refrigerant pump 53, and temperature sensors 56a and 56b that measure the refrigerant temperature. Yes. When the refrigerant flow rate or the refrigerant pressure is out of the correct range, the control device 58 detects an abnormality in the cooling system, restricts or stops the output of the fuel cell system, and avoids a decrease in life due to an increase in the internal temperature of the fuel cell stack 51. To do.
JP 2002-184435 A

  The protection device of the fuel cell system disclosed in Patent Document 1 performs abnormal control before sudden failure such as refrigerant leakage, air lock, instantaneous stop of the refrigerant pump 53, etc. before exceeding the lifetime reduction limit temperature. It is possible to avoid a decrease in the life due to the occurrence of a general abnormality.

  However, even if such a sudden abnormality does not occur, gas enters the refrigerant pipe 63 and the temperature of the cells in the fuel cell stack 51 is higher than the temperature measured by the temperature sensors 56a and 56b. There is. Even when this state continues, the fuel cell stack 51 cannot sufficiently obtain the required cooling amount, and there is a possibility that the deterioration of the fuel cell stack 51 is accelerated. The protection device of Patent Document 1 does not consider such a case, and cannot reduce the life of the fuel cell.

  A first feature of the present invention is that a refrigerant pump that circulates a refrigerant between the fuel cell stack and the radiator, a tank that stores the refrigerant, a refrigerant amount detecting means that detects or estimates the amount of the refrigerant, and a temperature of the refrigerant. Temperature detecting means for detecting or estimating, pressure detecting means for detecting or estimating refrigerant pressure, refrigerant pressure detected by the pressure detecting means, refrigerant temperature detected by the temperature detecting means, and refrigerant detected by the refrigerant amount detecting means The gist of the present invention is that it is a fuel cell cooling system provided with determination means for determining whether the amount of refrigerant is normal or abnormal from the amount of the above.

  The second feature of the present invention is that the refrigerant amount detection means detects the amount of refrigerant circulating between the fuel cell stack and the radiator, the temperature detection means detects the refrigerant temperature, and the pressure detection means detects the refrigerant pressure. The fuel cell stack starts operation by detecting and adding correction based on the temperature and pressure of the refrigerant detected by the temperature detection means and the pressure detection means to the amount of refrigerant before the fuel cell stack starts operation. After the fuel cell operation detected by the refrigerant amount detection means, the amount of the refrigerant after the start of operation is compared with the amount of refrigerant after the fuel cell operation detected by the refrigerant amount detection means. If the amount of the refrigerant is larger than the estimated amount of refrigerant after operation, the gist of the present invention is a method for protecting the fuel cell system that determines that gas is mixed in the fuel cell cooling system.

  According to the present invention, it is possible to provide a fuel cell cooling system and a fuel cell system protection method that maintain the cooling performance of the fuel cell stack even after gas is mixed into the liquid circulation system of the fuel cell system.

  Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  As shown in FIG. 1, the fuel cell cooling system according to the embodiment of the present invention includes a refrigerant pipe 13 connected to a refrigerant passage disposed inside the fuel cell stack 1 and a refrigerant circulating in the refrigerant pipe 13. A radiator 2 for cooling, a refrigerant pump 3 for circulating refrigerant between the fuel cell stack 1 and the radiator 2, a tank 4 for storing refrigerant, and a water level as an example of refrigerant quantity detecting means for detecting or estimating the quantity of refrigerant Detector 5, first temperature sensor 6a and second temperature sensor 6b as an example of temperature detecting means for detecting or estimating the temperature of the refrigerant, and pressure detection as pressure detecting means for detecting or estimating the pressure of the refrigerant , A control device 8 for controlling the entire fuel cell cooling system, and a notification means for notifying the user of an abnormality when the control device 8 detects that the amount of refrigerant is abnormal And a notification section 11 of the.

  In addition to the fuel cell 1 and the radiator 2, a refrigerant pump 3, a tank 4, a pressure detector 7, a first temperature sensor 6 a, a second temperature sensor 6 b, and a water level detector 5 are provided on the refrigerant pipe 13. ing. The refrigerant passage, the refrigerant pipe 13, the radiator 2 and the tank 4 inside the fuel cell stack 1 are filled with refrigerant.

  The fuel cell stack 1 generates electricity directly by electrochemically reacting hydrogen in the fuel gas with oxygen in an oxidant gas such as air, and generates heat as the power is generated. The refrigerant absorbs heat from the fuel cell stack 1 and is cooled by the rotation of the radiator fan 12 when passing through the radiator 2. As a result, the heat from the fuel cell stack 1 is released to the outside of the apparatus via the refrigerant and the radiator 2.

  The tank 4 stores refrigerant or separates gas and liquid. The pressure detector 7 detects the discharge pressure of the refrigerant pump 3. The first temperature sensor 6 a measures the refrigerant temperature near the entrance of the fuel cell stack 1. The second temperature sensor 6b measures the refrigerant temperature near the outlet of the fuel cell stack 1. The water level detector 5 detects the water level of the refrigerant in the tank 4.

  The control device 8 determines the amount of refrigerant from the refrigerant pressure detected by the pressure detector 7, the refrigerant temperature detected by the first and second temperature sensors 6 a and 6 b, and the refrigerant amount detected by the water level detector 5. As a determination unit 9 as a determination unit for determining whether normal or abnormal, and when the determination unit 9 determines that gas is mixed in the fuel cell cooling system, as an abnormality control unit for increasing the flow rate or cooling capacity of the refrigerant The abnormality control unit 10 is provided. When the determination unit 9 determines that the gas is mixed in the fuel cell cooling system, the notification unit 11 notifies the user of the abnormality.

  The determination unit 9 is based on the refrigerant temperature and pressure detected by the first and second temperature sensors 6a and 6b and the pressure detector 7 with respect to the refrigerant quantity before the fuel cell operation detected by the water level detector 5. The amount of refrigerant after operation is estimated by applying correction. Thereafter, the “estimated amount of refrigerant after operation” is compared with “the amount of refrigerant after operation of the fuel cell detected by the water level detector 5”. If the “amount of refrigerant after operation of the fuel cell detected by the water level detector 5” is larger than the “estimated amount of refrigerant after operation”, it is determined that gas is mixed in the fuel cell cooling system.

  Specifically, measurement signals from the pressure detector 7, the first and second temperature sensors 6 a and 6 b, and the water level detector 5 are respectively input to the control device 8. The control device 8 includes “total refrigerant volume data by tank water level”, “refrigerant volume expansion coefficient data by temperature change”, “volume data at each water level of the tank”, “tank water level change data by pump discharge pressure”, and “normal Built-in internal data storage for storing “water level threshold”. And the determination part 9 in the control apparatus 8 is based on the measurement signal from these sensors, and the 2nd in the tank 4 by the 1st water level change amount in the tank 4 by the temperature change and the discharge pressure of the refrigerant pump 3 is obtained. The amount of water level change is calculated. Then, correction is performed by adding the first water level change amount and the second water level change amount to the water level in the tank before operation, and the estimated refrigerant amount after operation is obtained. Then, it is determined whether or not the estimated refrigerant amount after operation is within the normal range by collating with the normal water level range based on the normal range data of the water level.

  The above-mentioned “total refrigerant volume data based on tank water level” is data indicating the volume of all refrigerants derived from the water level in the tank 4 detected by the water level detector 5, and has been previously tested or routed in the fuel cell cooling system. Calculated by volume calculation. When the change in the total refrigerant volume due to the tank water level is qualitatively expressed, the relationship is as shown in FIG.

  The “refrigerant volume expansion coefficient data due to temperature change” is data indicating the volume expansion coefficient of the refrigerant due to the change in the temperature of the refrigerant detected by the first and second temperature sensors 6a and 6b. In the case of water that is often used as a refrigerant in general, the relationship is as shown in FIG. Here, the “reference temperature T” of the refrigerant is 6.85 ° C., and the correction coefficient at this time is 1.

  The above “volume data at each water level of the tank” is data indicating the tank volume up to each water level obtained in advance by experiments. When the tank volume data at each water level is qualitatively expressed, the relationship is as shown in FIG.

  The above “tank water level change amount data due to pump discharge pressure” is data indicating the amount of water level change in the tank 4 due to the change in the discharge pressure of the refrigerant detected by the pressure detector 7 and is obtained in advance through experiments or calculations. .

  The “normal water level threshold value” is data indicating the normal range of the water level in the tank 4, and the amount of gas mixed that causes the internal temperature of the fuel cell stack 1 to be equal to or higher than the temperature sensor value by experiment or calculation in advance. And a value obtained by subtracting the sensor error from the calculated amount.

  The control device 8 transfers control signals to the refrigerant pump 3 and the radiator fan 12 to control the refrigerant flow rate and the air flow rate of the radiator 2, respectively. During normal operation, the control device 8 controls the refrigerant pump 3 and the radiator fan 12 so that the temperatures detected by the first and second temperature sensors 6a and 6b are within a predetermined range. Thereby, the operating temperature of the fuel cell stack 1 is maintained at a predetermined temperature.

  On the other hand, when the water level detected by the water level detector 5 deviates from the predetermined normal range, the determination unit 9 detects the gas mixture and determines the cooling system abnormality, and the abnormality control unit 10 The control of the radiator fan 12 is changed to the control at the time of abnormality. Specifically, the abnormality control unit 10 sets the amount obtained by subtracting the “estimated refrigerant amount after operation” from the “amount of refrigerant after fuel cell operation detected by the water level detector 5” as the “gas mixture amount”. From the “gas mixing amount”, an insufficient amount of cooling performance is calculated, and in order to maintain the cooling performance, the number of revolutions of the refrigerant pump 3 is increased by a predetermined amount, and the number of revolutions of the radiator fan 12 is increased. Increase cooling capacity. At the same time, the control device 8 gives a notification command to the notification unit 11 to notify the driver that there is an abnormality.

  The abnormality control unit 10 performs measures such as limiting the output of the fuel cell cooling system or stopping power generation instead of increasing the flow rate or cooling capacity of the refrigerant, or at the same time. You may avoid the life fall by internal temperature rise.

  Next, an abnormality detection operation by the control device 8 of the fuel cell cooling system of FIG. 1, that is, a method for protecting the fuel cell system will be described with reference to FIG.

  In addition to the abnormality detection, the control device 8 performs main control operations such as drive control of the refrigerant pump 3 and control of the radiator fan 12 in accordance with the output of the fuel cell stack 1 and the refrigerant temperature. The description is omitted because it is not directly related to the gist of the embodiment. The operation according to the flowchart of FIG. 5 is not particularly limited, but is configured as a subroutine that is called from the main control operation every predetermined time (for example, 0.05 seconds), for example.

  (A) First, in step S5, 1 is added to the value of t1, and the process proceeds to step S10. In step S10, it is determined whether t1 is smaller than t100. When t1 is less than t100 (YES in step S10), the process proceeds to step S20, and when t1 is t100 or more (NO in step S10), the process proceeds to step S120. Here, t100 is a predetermined constant obtained by dividing the time from when the control device 8 starts to operate until a predetermined time elapses by the control period. The predetermined time is the time before the operation of the fuel cell cooling system. In addition, although time management is used here, it may be managed by state transition.

  (B) In step S20, the coolant level L100 and the coolant temperature T100 in the tank 4 are detected using the water level detector 5 and the first or second temperature sensor 6a, 6b, and the storage device in the control device 400 The refrigerant water level L100 and the refrigerant temperature T100 before the operation of the fuel cell cooling system are stored. In step S30, the refrigerant volume V100 in the fuel cell cooling system at the refrigerant water level L100 before operation is calculated with reference to the “total refrigerant volume data based on the tank water level” stored in the control device 8, and the process goes to the main routine. Return. The estimated refrigerant volume V100 before operation is stored in the control device 8 as internal data.

  (C) On the other hand, in step S120, after starting the operation of the fuel cell cooling system, the refrigerant temperature T150 is detected using the first and second temperature sensors 6a and 6b. In step S130, with reference to “refrigerant volume expansion coefficient data due to temperature change” stored in the control device 8, the control device 8 changes from the refrigerant temperature T100 before operation to the refrigerant temperature T150 after operation starts. The volume expansion coefficient of the refrigerant at the time is calculated and the volume expansion coefficient is applied to the refrigerant volume V100 to calculate the expanded refrigerant volume V150 after the start of operation. The expanded refrigerant volume V150 after the start of operation is stored in the control device 8 as internal data.

  (D) In step S140, a pure expansion volume is calculated from the difference between the expansion refrigerant volume V150 and the refrigerant volume V100 before operation, and the expansion volume and the water level L100 stored in the storage device in the control device 8, By referring to “volume data at each water level of the tank” stored in the storage device in the control device 8, the water level increase / decrease amount ΔL150 due to temperature change is calculated. The water level increase / decrease amount ΔL150 due to the temperature change is stored in the control device 8 as internal data.

  (E) In step S150, the pressure detector 7 is used to detect the refrigerant pressure P100. In step S160, referring to the refrigerant pressure P100 and “tank water level change amount data by pump discharge pressure” stored in the storage device in the control device 8, the water level increase / decrease amount ΔL200 by the pump discharge pressure is calculated. . The water level increase / decrease amount ΔL200 due to the pump discharge pressure is stored in the control device 8 as internal data.

  (F) In step S170, the initial water level L100 stored in the storage device in the control device 8, the water level increase / decrease amount ΔL150 due to temperature change, and the water level increase / decrease amount ΔL200 due to the pump discharge pressure are added to obtain an estimated water level L250. Is calculated. Thus, when the temperature of the cooling water rises with the operation of the fuel cell system, the amount of cooling water increased by the temperature rise is added to the initial water level. Further, the water level during operation is grasped by subtracting the decreasing water level from the initial water level by the rotation of the refrigerant pump 3. At the same time, an actual water level (actual water level) L300 is obtained using the water level detector 5.

  (G) In step S180, the water level obtained by adding the predetermined water level threshold value ΔL350 and the estimated water level L250 is compared with the actual water level L300 to determine whether or not the actual water level L300 is higher. When the actual water level L300 is higher (YES in step S180), it is determined that gas has entered the fuel cell cooling system, and the process proceeds to step S190, where both are the same or the actual water level L300 is lower ( In step S180, NO) it is determined that no gas is mixed in the fuel cell cooling system, and the process proceeds to step S210.

  (H) In step S190, 1 is added to the value of t2, and the flow proceeds to step S195. In step S195, it is determined whether t2 is greater than t200. When t2 is larger than t200 (YES in step S195), the process proceeds to step S200, and when t2 is t200 or less (NO in step S195), the process proceeds to step S210. Here, t200 is a predetermined constant obtained by dividing the time until it is determined that gas is mixed in the fuel cell cooling system by the control period.

  (I) In step S200, when it is detected that gas has entered the cooling system in the fuel cell system, an abnormality treatment and notification are performed. For example, the abnormality control unit 10 of the control device 8 controls the refrigerant pump 3 to rotate at the maximum rotation speed regardless of the temperatures detected by the first and second temperature sensors 6a and 6b, and the radiator fan 12 is also maximized. Control to rotate at the number of rotations. Alternatively, the amount of the insufficient refrigerant is calculated from the difference between the estimated refrigerant volume and the actual refrigerant volume, and the number of revolutions of the refrigerant pump 3 is increased or the number of revolutions of the radiator fan 12 is increased by an amount that compensates for the amount of the insufficient refrigerant. You may control. Control is performed so as to maintain the operating temperature of the fuel cell stack 1 within a predetermined temperature by operating the rotational speeds of the refrigerant pump 3 and the radiator fan 12. As another means, the output of the fuel cell stack 1 is limited or the operation of the entire fuel cell system is stopped. Also by these means, it is possible to suppress an increase in the internal temperature of the fuel cell stack 1 and to avoid a decrease in life. You may implement in combination with these measures by the abnormality control part 10 simultaneously. In addition, the notification unit 11 notifies the driver of the occurrence of an abnormality by turning on or blinking a warning lamp, sounding an alarm buzzer, or the like. Thereafter, the process returns to the main routine. On the other hand, in step S210, tt2 is set to 0 and the process returns to the main routine.

  As described above, according to the embodiment of the present invention, the refrigerant pressure in the fuel cell cooling system detected by the pressure detector 7 and the fuel cell cooling system detected by the first and second temperature sensors 6a and 6b. By determining whether the refrigerant amount is normal or abnormal from the refrigerant temperature inside, the normality / abnormality of the refrigerant amount can be accurately determined.

  The estimated amount of refrigerant after the start of operation (estimated water level L250) and the amount of refrigerant after operation of the fuel cell detected by the water level detector 5 (actual water level L300) are compared. By determining whether or not gas is mixed into the fuel cell, it is possible to more reliably detect gas mixing into the fuel cell cooling system.

  By taking the difference between the estimated amount of refrigerant after the start of operation (estimated water level L250) and the amount of refrigerant after operation of the fuel cell detected by the water level detector 5 (actual water level L300), By calculating the gas mixing amount and increasing the refrigerant flow rate or cooling capacity equivalent to the insufficient refrigerant amount, the required cooling performance can be satisfied and the life of the fuel cell can be avoided without consuming more power than necessary. Can do.

  When gas is mixed in the fuel cell cooling system, the abnormality control unit 10 increases the refrigerant flow rate or cooling capacity to compensate for insufficient cooling performance and suppress the decrease in the life of the fuel cell. You can continue driving.

  When gas is mixed in the fuel cell cooling system, the abnormality control unit 10 limits the output of the fuel cell stack 1, thereby suppressing deterioration of the fuel cell and allowing the fuel cell to continue operating even after gas mixing. .

  When gas is mixed in the fuel cell cooling system, the abnormality control unit 10 can stop the operation of the fuel cell system, thereby avoiding a decrease in the life of the fuel cell.

  When gas is mixed in the fuel cell cooling system, the notification unit 11 notifies the driver of the abnormality, so that the driver can grasp the gas mixing at an early stage and can perform the removal operation.

  As described above, the present invention has been described by way of one embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. That is, it should be understood that the present invention includes various embodiments not described herein. Therefore, the present invention is limited only by the invention specifying matters according to the scope of claims reasonable from this disclosure.

1 is a block diagram showing a fuel cell cooling system according to an embodiment of the present invention. It is a graph which represents qualitatively the relationship between a tank water level and the total refrigerant | coolant volume. It is a graph which represents qualitatively the relationship between the temperature of a refrigerant | coolant, and the volume expansion coefficient (correction coefficient) of a refrigerant | coolant. It is a graph which represents qualitatively the relationship between a tank water level and a tank volume. It is a flowchart explaining the control procedure of the fuel cell cooling system of FIG. 10 is a block diagram showing a protection device for a fuel cell system disclosed in Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 51 ... Fuel cell stack 2, 52 ... Radiator 3, 53 ... Refrigerant pump 4 ... Tank 5 ... Water level detector (refrigerant amount detection means)
6a ... 1st temperature sensor (temperature detection means)
6b ... Second temperature sensor (temperature detection means)
7, 57 ... Pressure detector (pressure detecting means)
8, 58... Control device 9... Determination unit (determination means)
10: Abnormal control unit (abnormal control means)
11… Notification Department (notification means)
DESCRIPTION OF SYMBOLS 12 ... Radiator fan 13, 63 ... Refrigerant piping 54 ... Flow rate detector 56a, 56b ... Temperature sensor

Claims (10)

A refrigerant pump for circulating refrigerant between the fuel cell stack and the radiator;
A tank for storing the refrigerant;
Refrigerant amount detection means for detecting or estimating the amount of the refrigerant;
Temperature detecting means for detecting or estimating the temperature of the refrigerant;
Pressure detecting means for detecting or estimating the pressure of the refrigerant;
Whether the amount of the refrigerant is normal or abnormal is determined from the pressure of the refrigerant detected by the pressure detection unit, the temperature of the refrigerant detected by the temperature detection unit, and the amount of the refrigerant detected by the refrigerant amount detection unit. A fuel cell cooling system comprising: a determination unit.   The determination unit corrects the amount of the refrigerant before the fuel cell operation detected by the refrigerant amount detection unit based on the temperature and pressure of the refrigerant detected by the temperature detection unit and the pressure detection unit. The amount of the refrigerant after operation is estimated, and the estimated amount of refrigerant after operation is compared with the amount of refrigerant after operation of the fuel cell detected by the refrigerant amount detection means, and the refrigerant amount detection means 2. The fuel cell cooling system according to claim 1, wherein when the detected amount of the refrigerant after operation of the fuel cell is larger than the estimated amount of refrigerant after the operation, it is determined that gas is mixed in the fuel cell cooling system. Fuel cell cooling system.   3. The fuel cell cooling according to claim 2, further comprising an abnormality control means for increasing the flow rate or cooling capacity of the refrigerant when the determination means determines that gas is mixed in the fuel cell cooling system. system.   3. The fuel cell cooling system according to claim 2, further comprising an abnormality control unit that limits an output of the fuel cell stack when the determination unit determines that gas is mixed in the fuel cell cooling system. .   3. The fuel cell cooling system according to claim 2, further comprising an abnormality control unit that stops the operation of the fuel cell stack when the determination unit determines that gas is mixed in the fuel cell cooling system.   6. The apparatus according to claim 2, further comprising notification means for notifying the user of an abnormality when the determination means determines that gas is mixed in the fuel cell cooling system. Fuel cell cooling system.   When the determination unit determines that gas is mixed in the fuel cell cooling system, the abnormality control unit detects the estimated amount of the refrigerant after operation and the fuel cell operation detected by the refrigerant amount detection unit. The amount of the gas mixed into the fuel cell cooling system is calculated by taking the difference from the amount of the refrigerant, and the flow rate or cooling capacity of the refrigerant equivalent to the insufficient amount of the refrigerant is increased. The fuel cell cooling system according to claim 3, wherein the cooling performance is insufficient.   When the determination unit determines that gas is mixed in the fuel cell cooling system, the abnormality control unit detects the estimated amount of the refrigerant after operation and the fuel cell operation detected by the refrigerant amount detection unit. The flow rate or cooling capacity of the refrigerant is increased, the output of the fuel cell stack is limited, or the amount of the gas mixed into the fuel cell cooling system is calculated according to the difference from the amount of the refrigerant. 3. The fuel cell cooling system according to claim 2, wherein a flow rate or cooling capacity of the refrigerant equivalent to an amount of the insufficient refrigerant is increased.   2. The fuel cell cooling system according to claim 1, wherein the refrigerant amount detection means is a water level detector that detects a water level of the refrigerant in the tank. The refrigerant amount detection means detects the amount of refrigerant circulating between the fuel cell stack and the radiator,
Temperature detecting means detects the temperature of the refrigerant;
Pressure detecting means detects the pressure of the refrigerant;
The fuel cell stack operates by correcting the amount of the refrigerant before the fuel cell stack starts operation based on the temperature and pressure of the refrigerant detected by the temperature detection unit and the pressure detection unit. Estimating the amount of the refrigerant after starting
Comparing the estimated amount of refrigerant after the start of operation with the amount of refrigerant after operation of the fuel cell detected by the refrigerant amount detection means;
When the amount of the refrigerant after the fuel cell operation detected by the refrigerant amount detection means is larger than the estimated refrigerant amount after the operation, it is determined that gas is mixed in the fuel cell cooling system. A method for protecting a fuel cell system.

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