JP2004146187A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system in which precision for determining the frozen state of water in a water tank is enhanced. <P>SOLUTION: A pressure sensor 23 to detect the pressure of the water is installed in a through conduit of piping 21 in which the pressure of the water is regulated by a pressure control valve 22, and based on the pressure detection result of the pressure sensor 23, the frozen state of the water in the water tank 18 is determined. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell system that accurately grasps a frozen state of stored water.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as this type of fuel cell system, for example, one described in the following document is known (see Patent Document 1).
[0003]
This document describes a fuel cell power generation system that can be stably started in a low-temperature environment such as a cold region. This fuel cell power generation system includes a tank for storing water to be supplied to a fuel gas humidifying unit or an oxidizing gas humidifying unit, and the tank includes a main tank water tank and a spare tank auxiliary tank. During normal operation, the water supplied from the water tank is supplied to the humidifier and the fuel reformer, respectively.When the fuel cell power generation system is started or the water tank is empty, the water stored in the auxiliary tank is supplied to the humidifier and the fuel reformer. Each is supplied to the fuel reformer.
[0004]
That is, at the time of startup, the heater generates heat to heat the auxiliary tank and melt the water solidified in the auxiliary tank. Therefore, water can be supplied from the auxiliary tank to the humidifier and the fuel reformer. The control unit detects the temperature in the auxiliary tank, and starts the supply of water from the auxiliary tank to the humidifier and the fuel reformer if the water contained therein has not solidified. Thereby, power generation by the fuel cell is started. When the control unit confirms that the water in the water tank has melted, the control unit starts supplying water from the water tank.
[0005]
As described above, it is possible to melt the water that has solidified in the fuel cell and to secure the water necessary for startup.
[0006]
[Patent Document 1]
JP 2000-149970 A
[Problems to be solved by the invention]
As described above, in the conventional fuel cell system, the determination of freezing of water is made based on the temperature in the tank. The ice in the tank becomes water and ice when thawing begins. When water and ice coexist statically, the temperature of the water is kept at 0 ° C. However, when the ice is thawed by applying heat from the outside of the tank, it is difficult to determine whether or not ice exists inside even if the temperature of the water on the outer periphery increases. For this reason, when judging thawing based on temperature, it was necessary to judge that the tank was thawed when the temperature had risen sufficiently.
[0008]
When judging the thawing of the ice in the tank in this way, there is a problem that not only the start-up time of the fuel cell system is prolonged, but also extra energy is used by performing unnecessary heating. .
[0009]
In addition, in order to start the system early, if it is determined that the tank has thawed when the temperature in the tank has reached near the freezing point, ice may remain inside the tank depending on external environmental requirements and conditions such as the inclination of the vehicle. It is assumed that it remains. In such a case, there is a problem that the water supply amount is insufficient with respect to the volume of the entire water supply system, and there is a possibility that the water cannot be supplied satisfactorily.
[0010]
Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a fuel cell system with improved accuracy in determining the freezing state of water in a water tank.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a means for solving the problem of the present invention is a storage means for storing water, a humidifying means for humidifying the air by supplying the water stored in the storage means, and a storage means for the storage means. Supply means for supplying stored water to the humidifying means, pressure adjusting means for adjusting the pressure of water supplied to the humidifying means by the supply means, the storage means, the supply means, the humidifying means and the A fuel cell comprising a water supply system having a pipe communicating with a pressure adjusting means and having a pipe that guides water discharged from the storing means to the storing means again through the supplying means, the humidifying means, and the pressure adjusting means. In the system, in the flow path of the pipe in which the pressure of the water is regulated by the pressure regulating means, a pressure detecting means for detecting a pressure of the water, and based on a detection result of the pressure detecting means, It characterized by having a determining means for determining the frozen state of the water in the built means.
[0012]
【The invention's effect】
According to the present invention, since the frozen state of the water stored in the storage means is determined based on the water pressure in the flow path to which the water stored in the storage means is supplied, the water stored in the storage means is determined. The frozen state of water can be determined with high accuracy.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a diagram showing the configuration of the fuel cell system according to the first embodiment of the present invention. The fuel cell system according to the first embodiment shown in FIG. 1 includes a fuel cell body (FC stack) 1, a hydrogen tank 3 for storing hydrogen supplied to the FC stack 1, and an FC stack by humidifying air with water. 1, a humidifier 12, a water tank 18 for storing water supplied to the humidifier 12, a pump 19 for supplying water stored in the water tank 18 to the humidifier 12, a humidifier 12, and a water tank A pressure regulating valve 22 for regulating the pressure of the water flowing between the pressure regulators 18, a pressure detecting sensor 23 for detecting the pressure of the water regulated by the pressure regulating valve 22, and a control unit 31 for controlling the entire fuel cell system. It is configured.
[0015]
Further, the fuel cell system was adjusted to a desired pressure by the stack temperature sensor 2 for measuring the temperature of the FC stack 1, a pressure control valve 4 for reducing the pressure of the hydrogen tank 3 to a desired pressure, and a pressure control valve 4. An ejector 6 is provided for circulating hydrogen flowing in the normal circulation path 8 by utilizing fluid energy flowing through the fuel gas passage 5 later.
[0016]
The new hydrogen and the exhausted hydrogen after passing through the FC stack 1 in the ejector 6 are mixed and then supplied to the stack 1. The hydrogen that has passed through the FC stack 1 normally passes through the circulation path 8 and is guided to the ejector 6. When the concentration of impurities such as nitrogen and CO becomes high in the hydrogen circulation path, the purge valve 7 is opened, the circulating hydrogen is purged, and the hydrogen is guided to the exhaust hydrogen combustor 15. In the exhaust hydrogen combustor 15, the purged exhaust hydrogen and the stack exhaust air described later are mixed, burned, purified, and then discharged outside the vehicle.
[0017]
On the other hand, in the air passage 11, the air pumped into the pipe by the compressor 9 that sucks in and pumps outside air traps micro dust, sulfur content, oil discharged from the compressor 9, and the like by the filter 10. The purified air is humidified by a humidifier 12 provided in the air passage 11, and is supplied to the FC stack 1.
[0018]
The air remaining without being consumed by the FC stack 1 and the generated water are collected by a water condensing device 13 provided downstream thereof. Downstream thereof, a pressure control valve 14 capable of controlling the pressure of the air system to a desired pressure is provided. Further, an exhaust hydrogen combustor 15 is provided downstream thereof, and after purifying the exhaust hydrogen, the exhaust gas is exhausted as described above.
[0019]
In the present embodiment, the water condensing device 13 uses an air-cooled heat exchanger. However, the water condensing device 13 is not limited to a known one such as a water separation membrane or a device using cooling water. . The recovered water condensed and recovered by the water condensing device 13 is guided to a water tank 18 via a valve 16 for controlling the communication / non-communication of a water passage 17. In this embodiment, a filter is not particularly provided in the process of water recovery, but may be provided as needed. The water tank 18 is open to the atmosphere via a filter (not shown).
[0020]
The water flowing out of the water tank 18 is communicated by a pipe 20 to a pump 19 and a humidifier 12 on the downstream side. The pump 19 is on / off controlled by a command from the control unit 31 to pump water to the humidifier 12. The humidifier 12 is, for example, a film humidifier, and humidifies the cathode-side air. The water that has exited the humidifier 12 passes through a pipe 21, passes through a pressure sensor 23 that can detect the pressure in the pipe 21, and is given to a pressure regulating valve 22. The pressure regulating valve 22 keeps the water pressure between the pump 19 and the pressure regulating valve 22 substantially constant. The water that has passed through the pressure regulating valve 22 is returned to the water tank 18 again.
[0021]
In addition, in the piping connecting the air passage 11 and the piping 21, pipings 35 and 36 communicating with the water piping of the pressure regulating valve 22 near the humidifier 12 and the piping 21 of the pressure regulating valve 22 near the water tank 18 are provided. Are provided. A switching valve 34 that switches the air passage 11 and the water pipe 21 in communication and non-communication is provided in a pipe passage 35 of the common piping portion.
[0022]
In this pipe, when the system is stopped, if the temperature of the outside air temperature sensor 33 is equal to or lower than a predetermined value, water remaining in the pipe may be frozen. The water is collected in the water tank 18. In this way, by collecting the water in the pipe, it is possible to prevent the water in the pipe from freezing and taking a long time at the next startup. The water tank 18 is provided with a heater 18H. When the water in the water tank 18 is frozen at the time of starting the system, the heater 18H is operated to defrost the water.
[0023]
The humidification amount required for the operation of the FC stack 1 is supplied by the humidification device 12. In addition, in order to monitor the humidification amount by the control unit 31, the humidity after passing through the humidification device 12 is measured by the temperature and humidity sensor 32.
[0024]
As a cooling means for the heat generation of the FC stack 1, a mixture of water and an antifreezing agent such as ethylene glycol is used, and cooling is performed by flowing the cooling water passage in the FC stack 1. The cooling water that has taken the heat of the FC stack 1 is cooled by a three-way switching valve 24 that can be switched according to a command from the control unit 31 to a cooling passage between a passage 26 passing through a radiator 27 and a bypass passage 25 not passing through the radiator 27. Divided into
[0025]
The radiator 27 adjusts the radiator outlet water temperature to a desired temperature by a signal from the control unit 31 by a radiator fan (not shown). A reservoir tank 28 is provided in the temperature-controlled cooling water passage. The reservoir tank 28 is used for absorbing thermal expansion and contraction of the cooling water, replenishing the cooling water, and the like. A cooling water pump 29 is provided downstream of the cooling water pump 29. The cooling water is pressure-fed so as to have a flow rate determined by the control unit 31 according to the output of the stack temperature sensor 2 and is sent to the FC stack 1.
[0026]
The upper part of the reservoir tank 28 is open to the atmosphere and has a reservoir function. The control unit 31 receives various input signals in accordance with the input of the outside air temperature sensor 33, and outputs various control signals based on the result of the judgment and the calculation of the input value. Further, the control unit 31 determines the frozen state of the water in the water tank 18 based on the operation described below.
[0027]
Next, the operation of the fuel cell system having the above configuration will be described with reference to the flowchart of FIG.
[0028]
First, in step S201, values from various sensors such as the stack temperature sensor 2, the pressure sensor 23, the temperature and humidity sensor 32, and the outside air temperature sensor 33 are read. Next, in step S202, it is determined whether the value Ta of the outside air temperature sensor 33 is equal to or greater than a threshold value Tth1. If it is less than the threshold, the process proceeds to step S203. It is assumed that the threshold value is set to, for example, 15 ° C.
[0029]
Next, in step S203, it is recognized that there is a possibility that the water tank 18 is frozen. Next, in step S204, the heater 18H of the water tank 18 is energized to promote thawing of the water tank 18. Next, in step S205, the pump 19 is driven.
[0030]
Next, in step S206, it is determined whether or not a predetermined time has elapsed after the drive of the pump 19. As a result of the determination, if the predetermined time has elapsed, the process proceeds to step S207, and if less than the predetermined time, the process returns. Here, it is assumed that the predetermined time is set to, for example, 2 seconds.
[0031]
Next, in step S207, it is determined whether or not the value of the pressure sensor 23 has increased with respect to the previously read value. If the number has increased, the process proceeds to step S208. If the number has not increased, the process proceeds to step S214. Since the value of the increase is difficult to determine when the sample period is short, for example, 10 ms, an average of, for example, 10 samples is calculated, and whether the value is increased by comparing with the average of the next 10 samples is determined. Is determined.
[0032]
Next, in step S208, it is recognized that the ice in the water tank 18 has been thawed. Next, in step S209, the heater 18 is turned off. Next, in step S210, the operation shifts to normal operation described later.
[0033]
On the other hand, in step S211, it is recognized that there is no possibility that the water tank 18 is frozen. Next, in step S212, the pump 19 is turned on. Next, in step S213, the process proceeds to a normal operation described later.
[0034]
On the other hand, in step S214, it is recognized that the water tank 18 has not been thawed. During this time, the power generation is controlled so as not to generate power. Next, in step S215, the pump 19 is stopped. Next, in step S216, the thawing determination subroutine is executed again, and thawing of water is continued.
[0035]
Next, the normal operation of step S210 and step S213 will be briefly described.
[0036]
The normal operation means that the fuel is supplied to the anode side of the FC stack 1 by the pressure reducing valve 4 on the anode side of the FC stack 1 according to the output corresponding to the accelerator opening of the driver = the fuel and the air amount corresponding to the electric power. Air is supplied to the cathode side of 1 by a compressor 9, and the air is humidified by a humidifier 12 and guided to the FC stack 1. The humidity at the entrance of the FC stack 1 is monitored by the temperature / humidity sensor 32. If the humidification amount is insufficient, the operating pressure is increased and the pressure of the humidifier 12 is also increased. It is controlled so as not to occur.
[0037]
In addition, the cooling pump 29 adjusts the flow rate so that the flow rate according to the calorific value of the FC stack 1 flows through the FC stack 1, and the flow rate is corrected according to the temperature of the FC stack 1 by the temperature sensor 2 of the FC stack 1. I have. When the temperature of the FC stack 1 is extremely low, the switching is performed by the switching valve 24 so that the FC stack 1 does not pass through the radiator 27 but passes through the bypass passage 25. The outlet temperature of the radiator 27 is controlled so as to maintain a substantially constant temperature by controlling the flow rate of a radiator fan (not shown) according to the temperature detected by the temperature sensor 2 of the FC stack 1.
[0038]
During operation, in the cathode side air system of the FC stack 1, water in the air discharged from the FC stack 1 is condensed and recovered by the water condensing device 13 and guided to the water tank 18 through the passage 17. Is stored.
[0039]
On the other hand, in the anode system of the FC stack 1, the exhaust gas from the FC stack 1 is circulated through the passage 8 and the ejector 6. However, since the concentration of impurities such as nitrogen in the air in the fuel gradually increases due to the permeation of the stack membrane or the like, the purge valve 7 is opened at predetermined intervals. As a result, hydrogen in the circulation path is purged, mixed with air by the catalyst in the exhaust hydrogen combustor 15 downstream thereof, purified by combustion, and exhausted.
[0040]
By the normal operation as described above, an output corresponding to the driver's accelerator operation is output from the fuel cell system, and the vehicle is driven by a motor (not shown).
[0041]
As described above, in the first embodiment, since the pressure sensor 23 is provided in the flow path where the water pressure is adjusted by the pressure adjusting valve 22, the freezing of water can be determined based on the pressure. Here, if the value detected by the pressure sensor 23 does not increase within a predetermined time after driving the pump 19, it is determined that the water in the water tank 18 is frozen. Water can be determined.
[0042]
Further, when freezing is not determined, the pump 19 is stopped, so that unnecessary power is not consumed and power consumption can be reduced. Further, when freezing is determined, the heater 18H is stopped, so that unnecessary power is not consumed and power consumption can be reduced.
[0043]
Until the ice in the water tank 18 is thawed, sufficient humidification water cannot be supplied to the FC stack 1 and the capacity of the FC stack 1 is reduced. Damage is avoided. Furthermore, when the system is stopped, the water in the pipes is collected in the water tank 18, so that when the system is started up, there is no water in the pipes connecting the humidifier 12 and the water tank 18. Thereby, when judging the frozen state in the water tank 18 based on the pressure, it is possible to prevent erroneous detection due to the influence of the pressure fluctuation due to the freezing of the water in the pipe.
[0044]
Next, a second embodiment of the present invention will be described.
[0045]
In the first embodiment described above, after the pump 19 is driven, it is determined whether or not the pressure of the water increases within a predetermined time to determine whether or not the pump 19 normally discharges water. Although the freezing in the water tank 18 is determined based on the result, the feature of the second embodiment is that the frozen state is determined when the water pressure is stabilized for a predetermined time. is there.
[0046]
When the water in the tank 18 is completely thawed, the pressure immediately rises as shown in FIG. 3, and even if slight instability is observed, the state immediately enters a stable state.
[0047]
On the other hand, when the water is not completely thawed, the water is not constantly sucked out by the pump 19, and as shown in FIG. Will continue. For this reason, in the second embodiment, similarly to the first embodiment, it is first determined whether or not the pressure has increased within a predetermined time after the drive of the pump 19 (steps S205, 206, and 207 in FIG. 2). When the pressure rises, the determination of pressure stabilization is further started as shown in FIG. This determination of stabilization determines whether or not a pressure exceeding, for example, ± 10% with respect to the average value of pressure up to that time has not been generated for a predetermined time. Here, it is assumed that the predetermined time is set to, for example, 10 seconds. In the determination result, when a pressure exceeding, for example, ± 10% with respect to the average value of the pressure up to that time has not been generated for a predetermined time, it is determined that the water pressure has stabilized, and the ice in the water tank 18 is thawed. Recognize that
[0048]
In the second embodiment, as described above, the processing for determining the stabilization of the water pressure is employed, so that the frozen state in the water tank 18 is further reduced as compared with the first embodiment. It can be determined accurately.
[0049]
Next, a third embodiment of the present invention will be described.
[0050]
In the first embodiment described above, if no pressure increase is observed within a predetermined time after the start of driving of the pump 19, the water tank 18 is determined to be in a frozen state. However, in the third embodiment, Is characterized in that thawing is determined when the water pressure rises to a target pressure value (for example, 100 kPa).
[0051]
In the third embodiment, as shown in FIG. 5, when the water pressure falls within a range of ± 5% of the target pressure for a predetermined time, it is determined that the target value has been reached. Then, when the state continues for a predetermined time (for example, 15 seconds), it is determined that the thawing is performed, and the process shifts to the normal control.
[0052]
As described above, in the third embodiment, when the value detected by the pressure sensor 23 becomes the target value after the drive of the pump 19, it is determined that the ice in the water tank 18 is thawed. Therefore, the thawing of the ice can be accurately determined. Furthermore, after the water pressure becomes close to the target value, the condition that the state is stabilized for a predetermined period of time is also used as the determination condition, so that it is possible to more accurately determine the thawing of ice.
[0053]
FIG. 6 is a diagram illustrating a configuration of a fuel cell system according to a fourth embodiment of the present invention. A feature of the fourth embodiment is that a tank temperature sensor for measuring the temperature in the water tank 18 is used instead of the outside air temperature sensor 33 shown in FIG. 1 in the first embodiment shown in FIG. 38, and the other configuration is the same as that of FIG.
[0054]
Next, the operation of the fourth embodiment will be described with reference to the flowchart shown in FIG.
[0055]
7, in step S701, values from various sensors such as the stack temperature sensor 2, the pressure sensor 23, the temperature / humidity sensor 32, and the tank temperature sensor 38 are read. Next, in step S702, it is determined whether the temperature measured by the tank temperature sensor 38 is equal to or higher than a threshold. If it is less than the threshold, the process proceeds to step S703, and if it is not less than the threshold, the process proceeds to step S711. The threshold here is set near the freezing point, for example, 5 ° C. Further, since the set temperature of the threshold varies depending on the structure of the water tank 18 and the heating structure, it may be set according to the water tank 18 to be used.
[0056]
Next, in step S703, as a result of the determination in step S702, it is recognized that the water in the water tank 18 may be frozen. Next, in step S704, the heater 18H of the water tank 18 is energized to promote thawing of the water tank 18. Next, in step S705, the pump 19 is driven. Next, in step S706, it is determined whether or not a predetermined time has elapsed after the drive of the pump 19. As a result of the determination, if the predetermined time has elapsed, the process proceeds to step S707, and if less than the predetermined time, the process returns. The predetermined time here is set to, for example, 2 seconds.
[0057]
Next, in step S707, it is determined whether the water pressure has risen and the value of the pressure sensor 23 is stable near the target value. When it is stable, the process proceeds to step S708, and when it is not stable, the process proceeds to step S714. The determination method in this case is the same as in the third embodiment described above. Next, in step S708, it is recognized that the ice in the water tank 18 has been thawed. Next, in step S709, the heater 18H is turned off. Next, in step S710, the operation shifts to the normal operation.
[0058]
On the other hand, in step S711, it is recognized that there is no possibility that the water in the water tank 18 is frozen. Next, in step S712, the pump 19 is turned on. Next, in step S713, since the water in the water tank 18 is not frozen, the operation shifts to the normal operation.
[0059]
On the other hand, in step S714, it is recognized that the ice in the water tank 18 has not been thawed. Next, in step S715, the pump 19 is stopped, and the time after the stop is integrated. Next, in step S716, it is determined whether or not a predetermined time has elapsed after the stop of the pump 19 integrated in step S715. If the predetermined time has elapsed, the process proceeds to step S717. If the predetermined time has not elapsed, the determination process is repeated.
[0060]
During the elapse of the predetermined time, the heater heating of the water tank 18 is continued, and after the elapse of the predetermined time, the thawing determination subroutine is executed again to continue the thawing of the ice. The predetermined time here is set to be longer as the temperature in the water tank 18 is lower and to be shorter as the temperature in the water tank 18 is higher as shown in FIG. 8, for example. This is because, when the temperature for freezing and the like are different from each other, the thawing time is considered to be shorter as the temperature is higher, so that it is possible to shift to the normal control immediately after the thawing judgment.
[0061]
As described above, in the fourth embodiment, the tank temperature sensor 38 for detecting the temperature of the water in the water tank 18 is provided, and the freezing judgment by the pressure sensor 23 is performed when the temperature is near the freezing point. Therefore, the determination can be made quickly outside the temperature range, and the startup time can be reduced. Further, the time during which the pump 19 is stopped is set to be longer as the temperature of the tank temperature sensor 38 is lower, so that power is not wasted according to the time until thawing. .
[0062]
In the first to fourth embodiments, a humidifier is used as the humidifier 12. However, the present invention is not limited to this. A pure water passage is provided in the FC stack 1, and pure water is directly supplied to the FC stack 1 to separate the humidifier. The present invention is also applicable to a humidifier having no humidifier for the body.
[0063]
The correspondence between the constituent features of each of the above embodiments and the constituent features in the claims is as follows. That is, the water tank 18 serves as the storage means, the humidifier 12 serves as the humidifying means, the supply means serves as the pump 19, the pressure regulating valve 22 serves as the pressure regulating means, the pipes 20 and 21 serve as the pipes, and the pressure detecting means serves as the pressure sensor 23. The determining means corresponds to the control unit 31. The temperature detecting means corresponds to the tank temperature sensor 38, and the heating means corresponds to the heater 18H.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention.
FIG. 2 is a flowchart illustrating an operation of the fuel cell system according to the first embodiment of the present invention.
FIG. 3 is a diagram showing a change in water pressure when ice in a water tank is thawing.
FIG. 4 is a diagram showing a change in water pressure when ice in a water tank is not completely thawed.
FIG. 5 is a diagram for explaining an example of setting a target value of water pressure and determining thawing.
FIG. 6 is a diagram showing a configuration of a fuel cell system according to a fourth embodiment of the present invention.
FIG. 7 is a flowchart illustrating an operation of a fuel cell system according to a fourth embodiment of the present invention.
FIG. 8 is a diagram illustrating a relationship between a pump stop time and a temperature of a water tank.
[Explanation of symbols]
Reference Signs List 1 FC stack 2 Stack temperature sensor 3 Hydrogen tank 4 Pressure control valve 5 Fuel gas passage 6 Ejector 7 Purge valve 8 Normal circulation path 9 Compressor 10 Filter 11 Air passage 12 Humidifier 13 Moisture condensing device 14 Pressure control valve 15 Exhaust hydrogen combustor 16 Valve 17 Water passage 18 Water tank 18H Heater 19 Pump 20, 21 Pipe 22 Pressure regulating valve 23 Pressure sensor 24 Switching valve 25 Bypass passage 26 Flow passage 27 Radiator 28 Reservoir tank 29 Cooling water pump 31 Control unit 32 Temperature / humidity sensor 33 Outside air Temperature sensor 34 Switching valve 35, 36, 37 Pipe line 38 Tank temperature sensor

Claims (11)

Storage means for storing water;
Humidifying means for humidifying the air by providing the water stored in the storage means,
Supply means for supplying the water stored in the storage means to the humidification means,
Pressure adjusting means for adjusting the pressure of water supplied to the humidifying means by the supply means,
The storage means, the supply means, the humidification means and the pressure adjustment means are communicated, and the water discharged from the storage means is returned to the storage means via the supply means, the humidification means and the pressure adjustment means. A fuel cell system comprising a water supply system having a pipe for guiding
Pressure detection means for detecting the pressure of water, in the flow path of the pipe in which the pressure of water is regulated by the pressure adjustment means,
Determining means for determining a frozen state of water in the storage means based on a detection result of the pressure detection means. The determining means includes:
The water in the storage means is determined to be frozen if the pressure detection value by the pressure detection means does not increase within a predetermined time after the start of driving the supply means. Fuel cell system. The determining means includes:
After the start of driving the supply means, within a predetermined time, the pressure detection value by the pressure detection means has exceeded a predetermined range, and based on whether the state has continued for a predetermined time, whether or not the pressure detection value has stabilized. 2. The fuel cell system according to claim 1, wherein if the pressure detection value is not stable, it is determined that water in the storage unit is frozen. The determining means includes:
2. The method according to claim 1, wherein after starting the driving of the supply unit, when the pressure detection value by the pressure detection unit reaches a target value, it is determined that the water in the storage unit is not frozen. Fuel cell system. The determining means includes:
After the start of driving the supply unit, when the pressure detection value by the pressure detection unit is close to the target value and the state has been stably continued for a predetermined time, it is determined that the water in the storage unit is not frozen. The fuel cell system according to claim 1, wherein: Comprising a temperature detecting means for detecting a temperature of water in the storage means,
6. The method according to claim 1, wherein the determining unit performs the determining process when the temperature detected by the temperature detecting unit is near the freezing point. The fuel cell system according to item 1. 7. The method according to claim 1, wherein when the determination unit determines that the water in the storage unit is frozen, the driving of the supply unit is stopped. The fuel cell system according to claim 1. When the determination unit determines that the water in the storage unit is frozen, the drive of the supply unit is stopped, and a period during which the drive of the supply unit is stopped is detected by the temperature detection unit. 7. The fuel cell system according to claim 6, wherein the lower the temperature, the longer the setting. The power generation amount of the fuel cell system is limited while the water in the storage means is determined to be frozen by the determination means. The fuel cell system according to any one of claims 6, 7, and 8. The storage unit includes a heating unit that heats the stored water, and while the determination unit determines that the water in the storage unit is frozen, the storage unit operates the heating unit. The output of the heating means is reduced or stopped when it is determined that the water in the storage means is not frozen. 10. The fuel cell system according to any one of 8 and 9. The water supply system includes:
11. The water storage system according to claim 1, wherein the water remaining in the pipe is collected in the storage unit when the fuel cell system is stopped. The fuel cell system according to claim 1.

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