JP2019145334A - Fuel cell system - Google Patents

Abstract

To provide a fuel cell system that has excellent heat exchange performance in a cooling path used for the fuel cell system, etc. and maintains stable power generation by preventing air entrainment in the cooling path during initial water filling to the cooling path.SOLUTION: A fuel cell system (100) according to the present invention includes a fuel cell stack (1), a coolant circulation path (5) for flowing a coolant, a pump (6), a heat exchanger (7), and a tank (8). An air vent path (9) including an on-off valve (11) is provided in a second path (5b) of the coolant circulation path (5). By opening the on-off valve (11) during at least a part of a coolant filling term to the coolant circulation path (5), the air pool in the coolant circulation path (5) is discharged from an air vent path (9) to the atmosphere.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system that generates power by chemically reacting a fuel gas containing hydrogen and an oxidant gas.

  A fuel cell generates power by an electrochemical reaction between hydrogen in a fuel gas containing hydrogen gas as a main component and oxygen as an oxidant in the air. Since this electrochemical reaction is an exothermic reaction, heat is generated together with electricity during power generation. For this reason, the internal temperature of the fuel cell is maintained so that the operation temperature during power generation of the fuel cell is maintained at a temperature suitable for the reaction (for example, about 70 to 80 ° C. for a polymer electrolyte fuel cell) and power generation can be performed appropriately. In general, a mechanism for maintaining a constant value is employed.

  As a method of keeping the internal temperature of the fuel cell constant, there is a method of controlling the flow rate of the cooling water flowing through the cooling water circulation path arranged in the fuel cell (see, for example, Patent Document 1). Further, heat can be utilized by recovering heat of the high-temperature cooling water that has passed through the fuel cell by heat exchange in the exhaust heat recovery path by heat exchange.

  As shown in FIG. 3, Patent Literature 1 describes a fuel cell stack 102, a cooling water tank 103, a cooling water circulation pump 104, and a heat exchanger 108. In FIG. 3, the cooling water in the cooling water tank 103 is recovered by the cooling water circulation pump 104 through the fuel cell stack 102, and is circulated again to the cooling water tank 103 through the heat exchanger 108. Here, the exhaust heat recovery water, which is a heat medium, is conveyed to the heat exchanger 108 by the exhaust heat recovery pump 105, exchanges heat with the cooling water to become hot water, and is recovered in a hot water storage tank (not shown).

Japanese Patent Laid-Open No. 2005-100903

  However, in the conventional configuration, when the system is installed or restored after maintenance, the cooling water tank 103, the fuel cell stack 102, the cooling water circulation pump 104, and the cooling water circulation path that connects them (hereinafter referred to as cooling water circulation path) , Referred to as “water filling”), there is a problem in that air biting occurs and sufficient cooling performance cannot be obtained.

  That is, the cooling water circulation pump 104 circulates the cooling water so as to maintain the operating temperature of the fuel cell stack 102 during power generation at an appropriate temperature. However, when water accumulation occurs or stays in the cooling part of the fuel cell stack 102 during water filling, the fuel cell stack 102 cannot be sufficiently cooled with the cooling water. Further, when an air pool is generated or stays in the cooling water circulation pump 104, the cooling water circulation pump 104 generates air biting. When air is caught in the cooling water pump 104, the circulating flow rate of the cooling water is insufficient, and the fuel cell stack 102 cannot be sufficiently cooled. Further, when an air pocket is generated or stays in the heat exchanger 107, exhaust heat recovery by the heat exchanger 107 cannot be sufficiently performed.

  In view of the above problems, an object of the present invention is to prevent the occurrence of air accumulation in the cooling water circulation path disposed in the fuel cell system during water filling, to cool the fuel cell stack, and to cool the cooling water circulation path. An object of the present invention is to provide a fuel cell system excellent in heat exchange performance between water and the heat medium in the exhaust heat recovery path.

  In order to solve the above-described conventional problems, a fuel cell system according to an aspect of the present invention includes a fuel cell stack that generates power using a fuel gas containing hydrogen and an oxidant gas, and the fuel cell stack is generated during power generation. A cooling medium circulation path for flowing a cooling medium for recovering heat, a pump for circulating the cooling medium flowing in the cooling medium circulation path, a heat exchanger for recovering heat of the cooling medium flowing in the cooling medium circulation path, and the cooling A tank opened to the atmosphere for storing the cooling medium flowing through the medium circulation path, and the cooling medium circulation path is set to be lower than a prescribed water level of the cooling medium stored in the tank. A connection portion between the second route and the tank is set higher than a connection portion between the tank and the first route, and an air vent route is provided in the second route. It is those that are provided.

  As a result, when filling the cooling medium circulation path with water filling, the connecting part between the second path and the tank is set higher than the height of the connecting part between the tank and the first path. By utilizing this, the cooling medium circulation path can be filled with the cooling medium. In addition, since the air removal path is provided in the second path, the cooling medium enters from the second path during the supply of the cooling medium to the tank, and the air pool is confined in the cooling medium circulation path. In addition, the air reservoir can be discharged to the atmosphere from the air vent path, and air can be vented reliably.

  The fuel cell system of the present invention can prevent the occurrence of air accumulation in the cooling path used in the fuel cell system, and can realize a fuel cell system that has excellent heat exchange performance in the cooling path and continues stable power generation.

Schematic configuration diagram showing a cooling water path of the fuel cell system of the present invention Schematic configuration diagram showing a modification of the fuel cell system of the present invention Configuration diagram showing a conventional fuel cell system

  A fuel cell system according to a first aspect of the present invention includes a fuel cell stack that generates power using a fuel gas containing hydrogen and an oxidant gas, and a cooling medium that flows a cooling medium that recovers heat generated by the fuel cell stack during power generation A circulation path, a pump that circulates the cooling medium that flows through the cooling medium circulation path, a heat exchanger that recovers heat of the cooling medium that flows through the cooling medium circulation path, and a cooling medium that flows through the cooling medium circulation path are stored. A tank opened to the atmosphere, and the cooling medium circulation path includes a first path and a second path set lower than a prescribed water level of the cooling medium stored in the tank, and the second path The connecting portion of the tank is set higher than the connecting portion of the tank and the first path, and an air vent path is provided in the second path.

  According to the fuel cell system of the first invention, when the cooling medium circulation path is filled with the cooling medium in the water filling, the connection part between the second path and the tank is higher than the height of the connection part between the tank and the first path. Since it is set, the cooling medium circulation path can be filled with the cooling medium by using the specified water level of the tank. Further, since the air vent path is provided in the second path, even when the cooling medium enters from the second path while supplying the cooling medium to the tank, and the air pool is confined in the cooling medium circulation path. The air reservoir can be discharged to the atmosphere from the air vent path, and air can be vented reliably. Further, by preventing the occurrence of air accumulation in the cooling path used in the fuel cell system, it is possible to realize a fuel cell system that has excellent heat exchange performance in the cooling path and continues stable power generation.

  In the fuel cell system according to the second invention, in particular, in the first invention, the top end of the air vent path extends to a position higher than a specified height of the tank, and an open / close valve is provided in the air vent path. The on-off valve is opened at least during a period of water filling.

  According to the fuel cell system of the second aspect of the invention, since the top end of the air vent path is provided at a position higher than the prescribed water level of the tank, the water level in the air vent path does not reach the top end during filling. Therefore, it is possible to prevent the cooling medium from leaking from the air vent path during water filling.

  A fuel cell system according to a third aspect of the invention is the fuel cell system according to the second aspect of the invention, wherein, in the water filling, the on-off valve is closed after a storage amount of the cooling medium supplied to the tank satisfies a predetermined condition. It is.

  According to the fuel cell system of the third invention, it is determined that the cooling medium circulation path is filled with the amount of the cooling medium supplied to the tank satisfying the predetermined condition, and the on-off valve is closed. . Thus, by confirming that the cooling medium circulation path is filled with the cooling medium and then closing the on-off valve, it is possible to reliably remove air accumulation from the cooling medium circulation path. The predetermined condition can be set, for example, by associating the state in which the cooling medium circulation path is filled with the cooling medium in advance with the relationship between the storage amount of the cooling medium supplied to the tank.

  A fuel cell system according to a fourth aspect of the present invention is the fuel cell system according to the second and third aspects of the present invention, wherein the tank is provided above a connection portion between the tank and the second path, and is stored in the tank. In addition, an overflow path for overflowing the cooling medium is provided, and in the water filling, the on-off valve is closed after the cooling medium is discharged from the overflow path.

  According to the fuel cell system of the fourth aspect of the present invention, it is determined that the cooling medium is filled in the cooling medium circulation path by discharging the cooling medium from the overflow path, and the on-off valve is closed. Thereby, the timing which closes an on-off valve can be judged easily. The timing for closing the on-off valve may be the point in time when the discharge of the cooling medium from the overflow path is started, but is not limited to this. For example, the on-off valve may be closed after a predetermined time has elapsed since the discharge of the cooling medium from the overflow path.

  The fuel cell system according to a fifth aspect of the present invention is the fuel cell system according to the second and third aspects of the invention, in which the tank further includes a water level detector for detecting the water level in the tank, and the water level detector is a predetermined in the water filling. The on-off valve is closed after detecting the water level.

  According to the fuel cell system of the fifth aspect of the invention, it is determined that the coolant is filled in the coolant circulation path when the water level detector detects the predetermined water level, and the on-off valve is closed. Thereby, the timing which closes an on-off valve can be judged easily. In addition, although the timing which closes an on-off valve is good also as a time of a water level detector detecting a predetermined water level, it is not limited to this. For example, the on-off valve may be closed after a predetermined time has elapsed since the water level detector detected a predetermined water level.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
FIG. 1 is a configuration diagram showing a configuration example of a fuel cell system according to the first embodiment of the present invention. As shown in FIG. 1, the fuel cell system 100 includes a fuel cell stack 1 that generates power using a fuel gas containing hydrogen and an oxidant gas. For example, the fuel gas includes a reformed gas obtained by reforming a gas containing hydrocarbons such as city gas in a fuel processor, and a hydrogen gas supplied from an infrastructure. In FIG. 1, the action direction of gravity is the vertical direction.

  In the fuel cell stack 1, the fuel gas supplied to the anode 2 and the oxidant gas (for example, air) supplied to the cathode 3 react electrochemically (exothermic reaction) to generate electricity and heat. .

  The electricity generated by the fuel cell stack 1 can be used in various electric devices, for example. Further, the heat generated by the fuel cell stack 1 can be used for various purposes, for example, for heating or hot water supply in a home.

  A detailed description of the internal structure of the fuel cell stack 1 is omitted.

  Since the electrochemical reaction (exothermic reaction) proceeds in the power generation of the fuel cell stack 1, the operating temperature during the power generation of the fuel cell stack 1 is set to a temperature suitable for the reaction (for example, 70 for a polymer electrolyte fuel cell). In general, a mechanism for cooling the fuel cell stack 1 is employed.

  Next, a fuel cell cooling path for cooling the fuel cell stack 1 will be described.

  As shown in FIG. 1, the fuel cell cooling path includes a cooling medium circulation path 5 through which a cooling medium that recovers heat generated by the fuel cell stack 1 during power generation, and an open air that stores the cooling medium flowing through the cooling medium circulation path 5. The tank 8, the pump 6 that circulates the cooling medium flowing through the cooling medium circulation path 5, and the heat collected by the cooling medium from the fuel cell stack 1 are collected by the heat medium and stored in a hot water storage tank (not shown). An exhaust heat recovery path 17 and a heat exchanger 7 that performs heat exchange between the heat medium flowing through the exhaust heat recovery path 17 and the cooling medium flowing through the cooling medium circulation path 5 are provided. Examples of the cooling medium include pure water, tap water, and antifreeze.

  The cooling medium circulation path 5 includes a first path 5a and a second path 5b set lower than a prescribed water level of the cooling medium stored in the tank 8, and an air vent path 9 is provided in the second path 5b. Yes. Further, the connection portion between the second path 5 b and the tank 8 is set higher than the connection portion between the first path 5 a and the tank 8.

  The prescribed water level of the tank 8 is set based on the storage amount of the cooling medium in the tank 8 necessary for filling the cooling medium circulation path 5 with the cooling medium.

  The air vent path 9 is provided with an on-off valve 11 that can arbitrarily discharge the air and the cooling medium in the cooling medium circulation path 5 by performing opening / closing control. As the on-off valve 11, for example, an electromagnetic valve, a manual valve, an air vent plug, or the like can be used.

  In the first embodiment, the opening / closing valve 11 is an electromagnetic valve, and the opening / closing operation of the opening / closing valve 11 is controlled by the control unit 13. Note that the control unit 13 may control the operation of another device such as the pump 6.

  The air vent path 9 is configured to be opened to the atmosphere by opening the on-off valve 11.

  The water filling of the fuel cell system configured as described above will be described. Here, the water filling is to fill the cooling medium circulation path for cooling the fuel cell stack with a cooling medium (for example, pure water), for example, when the fuel cell system is constructed or restored after maintenance. Sometimes.

  First, the cooling medium is supplied to the tank 8. Here, the cooling medium is supplied from a supply port provided in the tank 8. In addition, as a method for supplying the cooling medium to the tank 8, a liquid feeding device such as a pump may be used, or the cooling medium may be naturally dropped.

  The on-off valve 11 is in an open state during at least a part period of water filling. Note that the timing for opening the on-off valve 11 may be before the start of supply of the cooling medium, or after the start of supply until the completion of water filling.

  In FIG. 1, the cooling medium supplied into the tank 8 passes through the cooling section 4 of the fuel cell stack 1 via the first path 5a, and passes through the pump 6 and the heat exchanger 7 in the second path 5b. Then, it is guided to the tank 8. Then, after the cooling medium flows again to the tank 8 via the second path 5b, it is stored in the tank 8 up to the height of the overflow path 12. When the water level in the tank 8 reaches the overflow path 12, the cooling medium is discharged from the overflow path 12.

  However, the cooling medium supply path from the tank 8 to the cooling medium circulation path 5 is not limited to the above. For example, when the supply speed to the tank 8 is higher than the speed at which the tank 8 flows into the coolant circulation path 5, the water level in the tank 8 rises before the coolant circulation path 5 is filled with the coolant, There is a case where the cooling medium enters from a connecting portion between the tank 8 and the second path 5b. Further, in the course of supplying the cooling medium to the tank 8, the cooling medium may occur and the cooling medium may enter from the connecting portion between the tank 8 and the second path 5b.

  As described above, when the cooling medium is supplied from the first path 5 a and the second path 5 b of the cooling medium circulation path 5, the air pool is confined in the cooling medium circulation path 5.

  According to the configuration of the first embodiment, by opening the on-off valve 11 provided in the air vent path 9 of the second path 5b, the air reservoir in the cooling medium circulation path 5 is changed from the air vent path 9 to the atmosphere. Can be discharged. This is particularly useful for configurations including elements with high pressure loss, such as fuel cell stacks and heat exchangers.

  In the first embodiment, the top end of the air vent path 9 is configured to extend to a position higher than the specified water level of the tank 8 defined by the overflow path 12. With this configuration, the water level of the cooling medium in the air vent path 9 does not reach the top end in the water filling. Therefore, it is possible to prevent the cooling medium from overflowing from the air vent path 9 during water filling. The on-off valve 11 may be provided at the top end.

  Next, the on-off valve 11 is closed after the storage amount of the cooling medium supplied to the tank 8 satisfies a predetermined condition. The predetermined condition can be set by associating the state in which the cooling medium circulation path is filled with the cooling medium in advance with the relationship between the storage amount of the cooling medium supplied to the tank.

  Accordingly, it can be determined that the coolant circulation path 5 is filled with the coolant because the amount of the coolant supplied to the tank satisfies the predetermined condition. By confirming that the cooling medium circulation path 5 is filled with the cooling medium, the on-off valve 11 is closed, so that air traps can be reliably removed from the cooling medium circulation path.

  In the first embodiment, the predetermined condition for the storage amount of the cooling medium supplied to the tank 8 is that after the cooling medium is discharged from the overflow path 12. By setting it as such a structure, the timing which closes the on-off valve 11 can be judged easily.

  The timing for closing the on-off valve 11 may be a point in time when the discharge of the cooling medium from the overflow path 12 is started, but is not limited thereto. For example, the on-off valve 11 may be closed after a predetermined time has elapsed since the discharge of the cooling medium from the overflow path 12 was started. However, it closes before the pump 6 starts operation.

  Here, when the on-off valve 11 is closed after a lapse of a predetermined time since the discharge of the cooling medium from the overflow path 12 is started, air accumulation in the cooling medium circulation path 5 can be surely eliminated. .

  Then, the cooling medium is discharged from the overflow path 12 to complete the water filling. After the water filling is completed, the operation of the pump 6 is started. By adopting a configuration in which the operation of the pump 6 is started after the air pool in the cooling medium circulation path 5 is eliminated, it is possible to prevent the pump 6 from being caught by air. Further, it is possible to prevent the heat exchange performance of the fuel cell stack and the heat exchanger from being lowered.

  After the water filling described above is completed, fuel gas and oxidant gas are supplied to the fuel cell stack 1, and electricity and heat are generated by power generation. The generated heat is recovered by the pump 6 into the cooling medium circulating in the cooling medium circulation path 5, is heat-exchanged by the exhaust heat recovery water in the heat exchanger 7, and is stored in a hot water storage tank (not shown). Become.

  In the first embodiment, the opening / closing operation of the on-off valve 11 is controlled by the control unit 13, but the present invention is not limited to this configuration. For example, the operator may manually control the on-off valve 11 by checking the supply state of the cooling medium to the tank 8 and the discharge state of the cooling medium from the overflow path 12.

(Embodiment 2)
Next, a fuel cell system according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a configuration diagram showing a configuration example of the fuel cell system according to the second embodiment of the present invention. In FIG. 2, the action direction of gravity is the vertical direction. Further, the same reference numerals are used for the same components as those in the first embodiment.

  The power generation mechanism of the fuel cell and the water filling of the fuel cell system are the same as those in the first embodiment, and thus detailed description thereof is omitted.

  As shown in FIG. 2, the fuel cell system 200 has a water level detector 14 in the tank 8. Here, the supply of the cooling medium to the tank 8 is performed via the cooling medium supply path 15 provided with the cooling medium supply valve 16. Here, the cooling medium supply valve 16 is an on-off valve, and for example, an electromagnetic valve, a manual valve, or the like can be used. In the second embodiment, the on-off valve 11 is a solenoid valve.

  In the second embodiment, the control unit 13 performs on / off control of the on-off valve 11 and the cooling medium supply valve 16 and communication with the water level detector 14.

  Hereinafter, water filling of the fuel cell system according to Embodiment 2 will be described. The definition of water filling is the same as in the first embodiment.

  First, the control unit 13 opens the cooling medium supply valve 16 and starts supplying the cooling medium to the tank 8 through the cooling medium supply path 15.

  The on-off valve 11 is in an open state during at least a part period of water filling. Note that the timing for opening the on-off valve 11 may be before the start of supply of the cooling medium, or after the start of supply until the completion of water filling.

  In FIG. 2, the cooling medium supplied into the tank 8 passes through the cooling section 4 of the fuel cell stack 1 via the first path 5a, and passes through the pump 6 and the heat exchanger 7 in the second path 5b. Then, it is guided to the tank 8. Then, after the cooling medium flows again to the tank 8 via the second path 5 b, it is stored in the tank 8. When the water level detector 14 detects that the water level in the tank 8 has reached a predetermined water level set in advance, the cooling medium supply valve 16 is controlled to be closed, and the supply of the cooling medium is stopped.

  The prescribed water level of the tank 8 is set based on the storage amount of the cooling medium in the tank 8 necessary for filling the cooling medium circulation path 5 with the cooling medium.

  However, the cooling medium supply path from the tank 8 to the cooling medium circulation path 5 is not limited to the above. For example, when the supply speed to the tank 8 is higher than the speed at which the tank 8 flows into the coolant circulation path 5, the water level in the tank 8 rises before the coolant circulation path 5 is filled with the coolant, There is a case where the cooling medium enters from a connecting portion between the tank 8 and the second path 5b. Further, in the course of supplying the cooling medium to the tank 8, the cooling medium may occur and the cooling medium may enter from the connecting portion between the tank 8 and the second path 5b.

  As described above, when the cooling medium is supplied from the first path 5 a and the second path 5 b of the cooling medium circulation path 5, the air pool is confined in the cooling medium circulation path 5.

  According to the configuration of the second embodiment, by opening the on-off valve 11 provided in the air vent path 9 of the second path 5b, the air pool in the cooling medium circulation path 5 is changed from the air vent path 9 to the atmosphere. Can be discharged.

  In the second embodiment, the top end of the air vent path 9 is configured to extend to a position higher than the prescribed water level of the tank 8. With this configuration, the water level of the cooling medium in the air vent path 9 does not reach the top end in the water filling. Therefore, it is possible to prevent the cooling medium from overflowing from the air vent path 9 during water filling. The on-off valve 11 may be provided at the top end.

  Next, the on-off valve 11 is closed after the storage amount of the cooling medium supplied to the tank 8 satisfies a predetermined condition. As for the predetermined condition, the state in which the cooling medium circulation path is filled with the cooling medium in advance and the water level in the tank detected by the water level detector 14 (reserved amount of the cooling medium supplied to the tank) are associated with each other. Can be set.

  Thereby, it can be determined from the fact that the water level in the tank satisfies the predetermined condition that the cooling medium circulation path 5 is filled with the cooling medium. By confirming that the cooling medium circulation path 5 is filled with the cooling medium, the on-off valve 11 is closed, so that air traps can be reliably removed from the cooling medium circulation path.

  In the second embodiment, the predetermined condition for the storage amount of the cooling medium supplied to the tank 8 is that after the water level detector 14 detects that the water level in the tank 8 has reached the predetermined water level. By setting it as such a structure, the timing which closes the on-off valve 11 can be judged easily.

  The timing at which the control unit 13 closes the on-off valve 11 may be a point in time when the control unit 13 detects that the water level in the tank 8 has reached a predetermined water level by the water level detector 14, but is not limited to this. For example, the on-off valve 11 may be closed after a predetermined time has elapsed since the control unit 13 detects that the water level in the tank 8 has reached a predetermined water level by the water level detector 14. However, it closes before the pump 6 starts operation.

  Here, when the water level detector 14 detects that the water level in the tank 8 has reached the predetermined water level, the on-off valve 11 is closed after a predetermined time has elapsed, so that the inside of the cooling medium circulation path 5 is surely established. The air pocket can be eliminated.

  And the control part 13 determines with the water filling having been completed because the water level detector 14 detected that the water level in the tank 8 reached the prescribed water level. After the water filling is completed, the operation of the pump 6 is started. By adopting a configuration in which the operation of the pump 6 is started after eliminating the air pool in the cooling medium circulation path 5, it is possible to prevent the occurrence of air jamming in the pump 6. Further, it is possible to prevent the heat exchange performance of the fuel cell stack and the heat exchanger from being lowered.

  After the water filling described above is completed, fuel gas and oxidant gas are supplied to the fuel cell stack 1, and electricity and heat are generated by power generation. The generated heat is recovered by the pump 6 into the cooling medium circulating in the cooling medium circulation path 5, is heat-exchanged by the exhaust heat recovery water in the heat exchanger 7, and is stored in a hot water storage tank (not shown). Become.

  In addition, in the said Embodiment 1 and Embodiment 2, although the pump 6 and the heat exchanger 7 were provided in the 2nd path | route 5b, this invention is not limited to this structure. Air is exhausted vertically by the action of gravity. Therefore, the pump 6 and the heat exchanger 7 are installed in the first path 5a lower than the prescribed water level of the tank 8, so that the air reservoir passes through the cooling unit 4 of the fuel cell stack 1 from the first path 5a. The air is discharged from the air vent path 9 provided in the two paths 5b or the tank 8 to the outside.

  In addition, in the said Embodiment 1 and Embodiment 2, the water discharge direction of the pump 6 is not limited.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  As described above, the fuel cell system according to the present invention can fill the cooling water circulation path, the heat exchanger, the fuel cell stack, and the cooling water circulation pump with cooling water without biting air. As a result, sufficient heat exchange performance satisfying the initial setting performance can be ensured and stable power generation can be performed, which is useful, for example, as a household fuel cell cogeneration system.

DESCRIPTION OF SYMBOLS 1 Fuel cell stack 2 Anode 3 Cathode 4 Cooling part 5 Cooling medium circulation path 5a 1st path 5b 2nd path 6 Pump 7 Heat exchanger 8 Tank 9 Air vent path 11 On-off valve 12 Overflow path 13 Control part 14 Water level detector 15 Cooling Medium supply path 16 Cooling medium supply valve 17 Waste heat recovery path 100 Fuel cell system 200 Fuel cell system

Claims (5)

A fuel cell stack for generating electricity using a fuel gas containing hydrogen and an oxidant gas;
A cooling medium circulation path for flowing a cooling medium for recovering heat generated by the fuel cell stack during power generation;
A pump for circulating the cooling medium flowing through the cooling medium circulation path;
A heat exchanger that recovers heat of the cooling medium flowing through the cooling medium circulation path;
A tank opened to the atmosphere for storing the cooling medium flowing through the cooling medium circulation path, and
The cooling medium circulation path includes a first path and a second path that are set lower than a prescribed water level of the cooling medium stored in the tank, and a connection portion between the second path and the tank is the tank and the tank. It is set higher than the connection part of the first route,
A fuel cell system, wherein an air vent path is provided in the second path. The topmost end of the air vent path extends to a position higher than a prescribed water level of the tank,
The air vent path is provided with an open / close valve,
The fuel cell system according to claim 1, wherein the on-off valve is opened at least during a period of water filling.   3. The fuel cell system according to claim 2, wherein in the water filling, the on-off valve is closed after a storage amount of the cooling medium supplied to the tank satisfies a predetermined condition. The tank is provided above a connection portion between the tank and the second path, and includes an overflow path for overflowing a cooling medium stored in the tank,
4. The fuel cell system according to claim 2, wherein, in the water filling, the on-off valve is closed after the cooling medium is discharged from the overflow path. The tank includes a water level detector that detects the water level in the tank,
The fuel cell system according to claim 2 or 3, wherein, in the water filling, the on-off valve is closed after the water level detector detects a predetermined water level.

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