Fuel battery system and control method of fuel battery system

Abstract

To provide a fuel battery cell system capable of suppressing gap corrosion due to an aqueous liquid flow path in which all or a part is formed of a metal material, and a control method of the fuel battery cell system.SOLUTION: A fuel battery cell system includes: a fuel battery cell having therein an aqueous liquid flow path through which an aqueous liquid having a function of supplying a hydrogen-containing gas from a hydrogen supply source to a fuel electrode, introducing an oxygen-containing gas such as air from an oxidizer gas supply source to an oxidizer electrode to perform power generation and removing at least a part of heat generated by the power generation flows, in which all or a part of the aqueous liquid flow path is made of a metal material; an aqueous liquid circulation flow path connected to the aqueous liquid flow path and capable of circulating the aqueous liquid; an aqueous liquid feeding part configured to circulate the aqueous liquid in the aqueous liquid circulation flow path; and a control part configured to control the aqueous liquid feeding part, in which the control part causes the aqueous liquid feeding part to operate at predetermined time intervals for a predetermined time in a state in which the fuel battery cell does not generate power.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a fuel cell system and a method for controlling a fuel cell system. [Background technology]

[0002] The electrochemical cell stack of a fuel cell is a laminate of cells, which are the smallest structural units of a fuel cell or electrolysis cell, and separators stacked in order. Fuel cells generate electricity by electrochemically reacting a fuel, such as hydrogen, with an oxidant, such as oxygen.

[0003] The separator in an electrochemical cell using a polymer membrane may be made of a metal material. Because metal materials have high strength, the weight of the separator can be reduced by making the separator from a metal material. In addition, the separator made of a metal material has an aqueous liquid flow path for cooling the fuel cell. In this way, when the separator is made of a metal material, all or part of the aqueous liquid flow path is made of a metal material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-272649 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when power generation by the fuel cell is stopped, concentration cells are formed due to the retention of eluted ions in the gaps of the metallic separator that comes into contact with the aqueous liquid, which may cause crevice corrosion.

[0006] Therefore, the problem to be solved by this embodiment is to provide a fuel cell system capable of suppressing crevice corrosion caused by aqueous liquid flow paths that are entirely or partially made of metal materials, and a method for controlling the fuel cell system. [Means for solving the problem]

[0007] The fuel cell system according to this embodiment generates electricity by supplying a hydrogen-containing gas from a hydrogen supply source to the fuel electrode and introducing an oxygen-containing gas such as air from an oxidant gas supply source to the oxidant electrode, and has an aqueous liquid flow path therein through which an aqueous liquid flows that has the function of removing at least a portion of the heat generated by the power generation, the aqueous liquid flow path being constructed entirely or partially from a metal material; an aqueous liquid circulation flow path connected to the aqueous liquid flow path and capable of circulating the aqueous liquid; an aqueous liquid delivery unit that circulates the aqueous liquid in the aqueous liquid circulation flow path; and a control unit that controls the aqueous liquid delivery unit, and the control unit operates the aqueous liquid delivery unit at predetermined time intervals when the fuel cell is not generating electricity. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress crevice corrosion caused by an aqueous liquid flow path that is entirely or partially made of a metal material. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of the overall configuration of a fuel cell system. [Figure 2] FIG. 2 is a top view showing the internal structure of a polymer electrolyte fuel cell stack. [Figure 3] FIG. 3 is a diagram schematically showing the cross section AA′ of FIG. 2. [Figure 4] FIG. 10 is a diagram schematically illustrating another example of a portion of a cross section of a separator. [Figure 5] 4 is a time chart showing a control example of the control device according to the present embodiment. [Figure 6] FIG. 10 is a diagram showing an example of the overall configuration of a fuel cell system according to a second embodiment. [Figure 7] 6 is a time chart showing a control example of a control device according to a second embodiment. [Figure 8] FIG. 10 is a diagram showing an example of the overall configuration of a fuel cell system according to a third embodiment. [Figure 9]FIG. 10 is a diagram showing an example of the overall configuration of a fuel cell system according to a fourth embodiment. [Figure 10] 10 is a time chart showing a control example of a control device according to a fourth embodiment. [Figure 11] FIG. 10 is a diagram showing an example of the overall configuration of a fuel cell system according to a fifth embodiment. [Figure 12] 10 is a time chart showing an example of control of a purge process in a control unit according to a fifth embodiment. [Figure 13] FIG. 10 is a diagram showing an example of the overall configuration of a fuel cell system according to a modified example of the first embodiment. [Figure 14] FIG. 10 is a diagram showing an example of the overall configuration of a fuel cell system according to a modified example of the second embodiment. [Figure 15] FIG. 11 is a diagram showing an example of the overall configuration of a fuel cell system according to a modified example of the third embodiment. [Figure 16] FIG. 11 is a diagram showing an example of the overall configuration of a fuel cell system according to a modified example of the fourth embodiment. [Figure 17] FIG. 13 is a diagram showing an example of the overall configuration of a fuel cell system according to a modified example of the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a fuel cell system and a control method for a fuel cell system according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the embodiment described below is an example of an embodiment of the present invention, and the present invention should not be interpreted as being limited to these embodiments. Furthermore, in the drawings referred to in this embodiment, identical parts or parts having similar functions are given the same or similar reference numerals, and repeated explanations thereof may be omitted. Furthermore, for convenience of explanation, the dimensional ratios of the drawings may differ from the actual ratios, and some components may be omitted from the drawings. (First embodiment)

[0011] First, the overall configuration of a fuel cell system 1 will be described with reference to Figures 1 to 4. Figure 1 is a diagram showing an example of the overall configuration of a fuel cell system 1. Figure 2 is an exploded perspective view of a fuel cell 5 including a separator 20 according to an embodiment. Figure 3 is a diagram showing a portion of a cross section of a fuel cell 5 including a separator 20 according to an embodiment. Figure 4 is a diagram showing a schematic view of a portion of a cross section of a separator 20 according to an embodiment.

[0012] 1, the fuel cell system 1 is a system that can periodically cause an aqueous liquid to flow through an aqueous liquid circulation channel 100c while power generation by the fuel cell system 1 is stopped. The fuel cell system 1 includes a fuel cell 5, a pump 100, an aqueous liquid circulation channel 100c, a radiator 102, and a control device 200. The fuel cell 5 may also be referred to as a fuel cell stack.

[0013] The fuel cell 5 is under the control of a control device 200, which will be described later, and its operation period is controlled. The fuel cell 5 can be used as a polymer electrolyte fuel cell stack. The fuel cell 5 can also be used as a polymer electrolyte electrolysis cell stack.

[0014] An aqueous liquid circulation flow path 100c is connected to the aqueous liquid flow path 21 of the fuel cell 5, and an aqueous liquid for cooling is supplied through the aqueous liquid circulation flow path 100c. A hydrogen-containing gas is mainly supplied as an anode fluid from a hydrogen gas supply source via a hydrogen gas flow path 31c to the anode fluid flow path 31. An oxygen-containing gas such as oxygen or air is mainly supplied as a cathode fluid from an oxidant gas supply source via an oxidant gas supply flow path 41c to the cathode fluid flow path 41 of the fuel cell 5. Substances other than those described above may be used as the anode fluid and the cathode fluid. In this embodiment, the oxygen-containing gas may be referred to as an oxidant gas in some cases. Furthermore, the hydrogen-containing gas may be simply referred to as hydrogen gas in some cases.

[0015] The pump 100 circulates the aqueous liquid in the aqueous liquid circulation channel 100c under the control of the control device 200. The pump 100 according to this embodiment corresponds to an aqueous liquid delivery section.

[0016] The radiator 102 cools the aqueous liquid in the aqueous liquid circulation channel 100c. As can be seen from this, the heat generated by the power generation of the fuel cell 5 is cooled by the aqueous liquid flowing through the aqueous liquid channel 21. For example, the aqueous liquid is pure water or an aqueous antifreeze solution.

[0017] The control device 200 controls the entire fuel cell system 1. The control device 200 is configured to include, for example, a CPU (Central Processing Unit), and is equipped with a control unit 202 and a storage unit 204. The control unit 202 executes control over the entire fuel cell system 1 in accordance with a program stored in the storage unit 204. An example of control by the control unit 202 according to this embodiment will be described later with reference to FIG. 5.

[0018] (fuel cell 5) 2 and 3, the fuel cell 5 has a structure in which a cell 10, an anode separator 30, and a cathode separator 40 are stacked as a set. The anode separator 30 and the cathode separator 40 form a pair to form the separator 20. The separator 20 is stacked with the cell 10 sandwiched between them.

[0019] The cell 10 includes a membrane electrode assembly (MEA) 11 and a cell outer frame 12. Hereinafter, the membrane electrode assembly will be referred to as the MEA 11. As shown in FIG. 3, the MEA 11 includes an anode electrode 13, a polymer electrolyte membrane 14, and a cathode electrode 15. The anode electrode 13, the polymer electrolyte membrane 14, and the cathode electrode 15 are configured in a flat plate shape. In this embodiment, the anode electrode 13 corresponds to the fuel electrode, and the cathode electrode 15 corresponds to the oxidant electrode.

[0020] An anode electrode 13 is provided on one side of the surface of a polymer electrolyte membrane 14, which is an ion exchange membrane, and a cathode electrode 15 is provided on the other side of the surface of the polymer electrolyte membrane 14. As shown in Fig. 2, a cell outer frame 12 is provided on the outer periphery of the MEA 11. The cell outer frame 12 is made of a material that is impermeable to gases.

[0021] The anode separator 30 is provided on the anode electrode 13 side. At least a portion of the anode separator 30 is in contact with the anode electrode 13. The cathode separator 40 is provided on the cathode electrode 15 side. At least a portion of the cathode separator 40 is in contact with the cathode electrode 15.

[0022] 3, the anode separator 30 and the cathode separator 40 have, for example, a corrugated shape with an isosceles trapezoidal cross section. The convex portions that form the upper base are formed alternately on the anode electrode 13 side and the cathode electrode 15 side in the direction in which the corrugated shape is formed.

[0023] Separator 20 is formed by overlapping and joining the upper base of anode separator 30 that protrudes toward cathode electrode 15 and the upper base of cathode separator 40 that protrudes toward anode electrode 13 .

[0024] An anode fluid flow path 31 for flowing an anode fluid is formed between the anode electrode 13 and the anode separator 30. A cathode fluid flow path 41 for flowing a cathode fluid is formed between the cathode electrode 15 and the cathode separator 40. An aqueous liquid flow path 21 for flowing a refrigerant is formed between the anode separator 30 and the cathode separator 40. As shown in FIG. 3 , the aqueous liquid flow path 21 is formed by the space inside the protruding portion of the anode separator 30 that protrudes toward the anode electrode 13, and the space inside the protruding portion of the cathode separator 40 that protrudes toward the cathode electrode 15. The aqueous liquid flow path 21 is made entirely or partly of a metal material.

[0025] An end surface 30a of the upper base of the anode separator 30 protruding toward the anode electrode 13 contacts the anode electrode 13. An end surface 40a of the upper base of the cathode separator 40 protruding toward the cathode electrode 15 contacts the cathode electrode 15.

[0026] 2, anode fluid manifolds 50, 50 for supplying and discharging anode fluid, cathode fluid manifolds 51, 51 for supplying and discharging cathode fluid, and refrigerant manifolds 52, 52 for supplying and discharging refrigerant are formed on the cell outer frame 12, the anode separator 30, and the cathode separator 40. One of the manifolds is a manifold for supplying fluid, and the other is a manifold for discharging fluid.

[0027] The flow paths for the anode fluid, cathode fluid, and refrigerant are sealed with sealant 60 to prevent leakage of the fluids to the outside. As shown in Fig. 1 , the sealant 60 for the cathode fluid is formed, for example, on the surface of the cathode separator 40 facing the cathode electrode 15. The sealant 60 for the refrigerant is formed, for example, on the surface of the anode separator 30 facing the cathode separator 40. The sealant 60 for the anode fluid is formed, for example, on the surface of the anode separator 30 facing the anode electrode 13.

[0028] Although an example in which the sealing material 60 is formed on the anode separator 30 and the cathode separator 40 has been shown here, the sealing material 60 may also be formed on the cell 10. Also, a gasket may be provided as the sealing material 60 between each surface to be sealed.

[0029] 2, the anode fluid flow channel 31, the cathode fluid flow channel 41, and the aqueous liquid flow channel 21 are shown as an example having a serpentine structure with multiple bends, but are not limited to this configuration. Each flow channel may also have a linear structure without bends.

[0030] For example, if hydrogen is used as the anode fluid and oxygen is used as the cathode fluid, hydrogen supplied to one anode fluid manifold 50 is introduced into the anode fluid flow channel 31. Oxygen supplied to one cathode fluid manifold 51 is introduced into the cathode fluid flow channel 41. Hydrogen and oxygen are used as reactants in the chemical reaction that accompanies power generation in the cell 10.

[0031] Hydrogen that is not used as a reactant is discharged to the outside from the other anode fluid manifold 50. Furthermore, oxygen that is not used as a reactant is discharged to the outside from the other cathode fluid manifold 51 together with the products of the chemical reaction.

[0032] Here, when the fuel cell 5 is used as a polymer electrolyte fuel cell stack or a polymer electrolyte electrolysis cell stack, the coolant supplied to one of the coolant manifolds 52 is introduced into the aqueous liquid flow path 21. After cooling the MEA 11, the coolant is discharged to the outside from the other coolant manifold 52.

[0033] Next, a detailed description will be given of the configuration of the separator 20. As shown in Fig. 4, the anode separator 30 and the cathode separator 40 that constitute the separator 20 include a substrate 80 and a corrosion-resistant film 90.

[0034] The substrate 80 is formed of a thin metal plate such as stainless steel (SUS), titanium, aluminum, an aluminum alloy, magnesium, or a magnesium alloy. Specifically, the substrate 80 is formed of one material selected from these materials.

[0035] The thickness of the base material 80 is, for example, about 0.1 mm. Here, by forming the base material 80 from aluminum, an aluminum alloy, magnesium, or a magnesium alloy, it is possible to achieve further weight reduction.

[0036] The substrate 80 is formed into, for example, the aforementioned isosceles trapezoidal wave shape by, for example, pressing the above-mentioned thin metal plate. The pressing may be performed before or after the corrosion-resistant film 90 is formed.

[0037] The corrosion-resistant film 90 prevents the substrate 80 from being corroded by exposure to an acidic atmosphere. The corrosion-resistant film 90 is formed on at least one surface 80a of the substrate 80. In the anode separator 30, the corrosion-resistant film 90 is formed at least on the surface of the substrate 80 facing the anode electrode 13. The surface of the substrate 80 facing the anode electrode 13 in the anode separator 30 refers to the entire surface of the substrate 80 that faces the anode electrode 13. In the cathode separator 40, the corrosion-resistant film 90 is formed at least on the surface of the substrate 80 facing the cathode electrode 15. The surface of the substrate 80 facing the cathode electrode 15 in the cathode separator 40 refers to the entire surface of the substrate 80 that faces the cathode electrode 15.

[0038] The corrosion-resistant film 90 is formed of a material that is both corrosion-resistant and conductive. The corrosion-resistant film 90 is formed of, for example, Ti, Ta, TiN, TaN, TiC, TaC, TiCN, TaCN, conductive carbon, or the like. Specifically, the corrosion-resistant film 90 is formed of multiple crystals of one material selected from these materials.

[0039] The corrosion-resistant film 90 is formed using a film formation method such as chemical vapor deposition (CVD), atomic layer deposition (ALD), or physical vapor deposition (PVD) such as sputtering. These film formation methods can form films with few defects and good embedding properties. These film formation methods can also form films with good coverage. Furthermore, these film formation methods can form films with uniform thickness even on the surface of the separator 20, which has an isosceles trapezoidal corrugated shape.

[0040] Here, when the substrate 80 is made of magnesium or a magnesium alloy, these materials are quickly oxidized in the atmosphere to form an oxide film. Therefore, in order to suppress the formation of an oxide film on the surface of the substrate 80, it is preferable to form the corrosion-resistant film 90 quickly after adjusting the surface roughness of the surface 80a of the substrate 80, or to form the corrosion-resistant film 90 using the substrate 80 that has been kept in an oxygen-free atmosphere.

[0041] An oxide film may be formed on the surface of the substrate 80 to function as a passivation film for improving corrosion resistance. If the passivation film is too thick, depending on the material, the insulating properties may become high and current may not flow easily. Therefore, the oxide film (passivation film) is formed to an appropriate thickness, taking into account corrosion resistance and insulating properties. For example, if the substrate 80 is made of aluminum, the thickness of the oxide film (aluminum oxide) is preferably 1 nm to 10 nm.

[0042] (Control example) 5 is a time chart showing an example of control by the control device 200 according to this embodiment. From the top, the chart shows changes over time in the power generation signal S1 of the fuel cell 5 and the drive signal S2 of the pump 100, both of which are output by the control unit 202. As shown in FIG. 5, the control device 200 according to this embodiment is capable of executing control to suppress crevice corrosion.

[0043] At time t1, the power generation signal S1 and the drive signal S2 fall from high to low. This stops the supply of oxidant gas from the oxidant gas supply source to the fuel cell 5 and the supply of hydrogen-containing gas from the hydrogen gas supply source, and power generation stops. Also, at time t1, the drive signal S2 falls from high to low, and the pump 100 stops.

[0044] At time t2, after a predetermined period of time has elapsed, drive signal S2 changes from low to high, and pump 100 is driven until time t3. More specifically, the integrated value of the flow rate of aqueous liquid flowing through aqueous liquid flow path 21 between times t2 and t3 is set to at least three times the maximum capacity of aqueous liquid circulation channel 100c, which includes aqueous liquid flow path 21. This allows aqueous liquid to flow between times t2 and t3 to an extent that enables it to flush out ions eluted from aqueous liquid flow path 21.

[0045] Thereafter, the pump 100 is driven periodically, such as between time t4 and time t5 after a certain time has elapsed, and between time t6 and time t7. The certain time intervals ta, tb, tc, etc. that determine the repetition period and the operating time from time t2 to t3 during which the pump 100 is driven can be set according to the characteristics of the fuel cell 5. It is also possible to control the time intervals ta, tb, tc, such as by sequentially increasing the intervals, according to the characteristics of the fuel cell 5.

[0046] As can be seen from this, before the influence of the eluted ions reaches the separator 20, the aqueous liquid flows sufficiently through the aqueous liquid flow paths 21, washing away the eluted ions, and this process is repeated periodically. This suppresses crevice corrosion of the aqueous liquid flow paths 21 in the separator 20.

[0047] As described above, according to this embodiment, even after power generation by the fuel cell 5 has stopped, the control device 200 periodically drives the pump 100 to control the aqueous liquid to flow through the aqueous liquid flow path 21. This causes the aqueous liquid to flow through the aqueous liquid flow path 21 and wash away eluted ions in a periodically repeated manner, thereby suppressing crevice corrosion of the aqueous liquid flow path 21 in the separator 20.

[0048] (Second embodiment) The fuel cell system 1 according to the second embodiment differs from the fuel cell system 1 according to the first embodiment in that an ion exchange resin bottle 104 is provided in the ion exchange resin flow path 100d of the aqueous liquid circulation flow path 100c. The differences from the fuel cell system 1 according to the first embodiment will be described below.

[0049] FIG. 6 is a diagram showing an example of the overall configuration of a fuel cell system 1 according to the second embodiment. The fuel cell system 1 according to the second embodiment further includes an ion exchange resin flow path 100d as a branch channel of the aqueous liquid circulation flow path 100c. An ion exchange resin bottle 104 is disposed in this ion exchange resin flow path 100d. The ion exchange resin bottle 104 adsorbs ions present in the aqueous liquid circulating through the ion exchange resin flow path 100d through an ion exchange reaction. As a result, the eluted ions are removed by the ion exchange resin bottle 104.

[0050] (Control example) 7 is a time chart showing an example of control by the control device 200 according to the second embodiment. From the top, the chart shows changes over time in the power generation signal S1 of the fuel cell 5 output by the control unit 202, the drive signal S2 of the pump 100, and the circulation period ts3 of the ion exchange resin flow path 100d. As shown in FIG. 7, the control device 200 according to this embodiment can also circulate the aqueous liquid through the ion exchange resin flow path 100d in response to the drive of the pump 100.

[0051] That is, the control device 200 periodically drives the pump 100 to control the aqueous liquid to flow through the aqueous liquid flow path 21 and the ion exchange resin flow path 100d even after the power generation of the fuel cell 5 has stopped. As a result, the aqueous liquid flows through the aqueous liquid flow path 21 and washes away the eluted ions before they have an effect on the aqueous liquid, and the ion exchange resin bottle 104 adsorbs, by an ion exchange reaction, the eluted ions present in the aqueous liquid circulating through the ion exchange resin flow path 100d.

[0052] As can be seen from this, before the influence of the eluted ions reaches the separator 20, the aqueous liquid flows through the aqueous liquid flow paths 21, washing away the eluted ions and then periodically adsorbing the eluted ions. This more efficiently suppresses crevice corrosion of the aqueous liquid flow paths 21 in the separator 20.

[0053] As described above, according to this embodiment, even after power generation by the fuel cell 5 has stopped, the control device 200 periodically drives the pump 100 to control the aqueous liquid to flow through the aqueous liquid flow path 21 and the ion exchange resin bottle 104. This periodically repeats the flushing of eluted ions and the adsorption of the eluted ions, thereby more efficiently suppressing crevice corrosion of the aqueous liquid flow path 21 in the separator 20.

[0054] (Third embodiment) The fuel cell system 1 according to the third embodiment differs from the fuel cell system 1 according to the second embodiment in that an aqueous liquid tank 106 is provided in the ion exchange resin flow path 100d of the aqueous liquid circulation flow path 100c. The differences from the fuel cell system 1 according to the second embodiment will be described below.

[0055] 8 is a diagram showing an example of the overall configuration of a fuel cell system 1 according to the third embodiment. The fuel cell system 1 according to the third embodiment further includes an aqueous liquid tank 106 in the ion exchange resin channel 100d as a branch channel of the aqueous liquid circulation channel 100c. The aqueous liquid tank 106 makes it possible to adjust the total amount of aqueous liquid circulating through the aqueous liquid circulation channel 100c. This makes it possible to dilute the eluted ions relative to the total amount of aqueous liquid.

[0056] A control example of the fuel cell system 1 according to the third embodiment is equivalent to the control example shown in FIG. 7. That is, the control device 200 periodically drives the pump 100 even after power generation by the fuel cell 5 is stopped, controlling the flow of the aqueous liquid through the aqueous liquid flow path 21 and the ion exchange resin flow path 100d. This allows the aqueous liquid to flow through the aqueous liquid flow path 21 and flush out the eluted ions before they affect the system. At the same time, the ion exchange resin bottle 104 adsorbs the eluted ions present in the aqueous liquid circulating through the ion exchange resin flow path 100d through an ion exchange reaction. At this time, the aqueous liquid tank 106 makes it possible to adjust the total amount of aqueous liquid in the entire fuel cell system 1, thereby enabling the dilution of the eluted ions.

[0057] (Fourth embodiment) The fuel cell system 1 according to the fourth embodiment differs from the fuel cell system 1 according to the third embodiment in that a circulation water channel 100e is further provided in the ion exchange resin channel 100d of the aqueous liquid circulation channel 100c, and a second pump 108 is provided. The differences from the fuel cell system 1 according to the third embodiment will be described below. The second pump 108 according to this embodiment corresponds to the second aqueous liquid delivery section.

[0058] 9 is a diagram showing an example of the overall configuration of a fuel cell system 1 according to a fourth embodiment. The fuel cell system 1 according to the fourth embodiment further includes a circulation water channel 100e connected to the ion exchange resin channel 100d. The fuel cell system 1 also includes a second pump 108 disposed in the circulation water channel 100e. The second pump 108 operates under the control of a control unit 202 of the control device 200.

[0059] The second pump 108 can be driven independently of the pump 100, and the amount and duration of the aqueous liquid circulating through the ion exchange resin flow path 100d can be made different from the amount and duration of the aqueous liquid circulating through the ion exchange resin flow path 100d and the circulation water path 100e, thereby making it possible to adjust the exchange reaction amount of the eluted ions.

[0060] (Control example) 10 is a time chart showing an example of control by the control device 200 according to the fourth embodiment. From the top, the chart shows changes over time in the power generation signal S1 of the fuel cell 5, the drive signal S2 of the pump 100, and the drive signal S3 of the second pump 108, all of which are output by the control unit 202. As shown in FIG. 10, when the control device 200 according to this embodiment executes control to suppress crevice corrosion, it controls the amount and duration of the aqueous liquid circulating through the ion exchange resin flow path 100d and the circulation water path 100e independently of the circulation through the aqueous liquid circulation flow path 100c.

[0061] At time t1, the power generation signal S1 and the drive signal S2 fall from high to low. This stops the supply of oxidant gas from the oxidant gas supply source to the fuel cell 5 and the supply of hydrogen-containing gas from the hydrogen gas supply source, and power generation stops. Also, at time t1, the drive signal S2 falls from high to low, and the pump 100 stops.

[0062] The pump 100 is driven in the same manner as in the first embodiment (see FIG. 5). That is, it is driven at regular time intervals ta, tb, and tc that define a repetition period. Meanwhile, the second pump 108 starts driving at time t2a, a predetermined time before time t2, and stops driving at time t3a, a predetermined time after time t3. That is, at time t2a, before time t2 when the aqueous liquid is controlled to flow through the aqueous liquid flow path 21, the eluted ions of the aqueous liquid stored in the aqueous liquid tank 106 are absorbed. This makes it possible to flow the aqueous liquid stored in the aqueous liquid tank 106, into which the eluted ions have been absorbed, through the aqueous liquid flow path 21.

[0063] Furthermore, the second pump 108 continues to be driven until time t3a, which is after time t3 when the circulation of the aqueous liquid to the aqueous liquid flow path 21 is stopped. This allows the absorption of eluted ions by the aqueous liquid stored in the aqueous liquid tank 106 to continue until time t3a. As can be seen from this, the aqueous liquid stored in the aqueous liquid tank 106 into which the eluted ions have been absorbed is flowed into the aqueous liquid flow path 21, thereby further efficiently suppressing crevice corrosion. The second pump 108 is driven at times t4a and t6a, as at time t2a, and is stopped at times t5a and t7a, as at time t3a.

[0064] In this way, before the influence of the eluted ions reaches the separator 20, the aqueous liquid flows through the aqueous liquid flow path 21, washing away the eluted ions. At this time, the aqueous liquid stored in the aqueous liquid tank 106 has already absorbed the eluted ions, further suppressing crevice corrosion of the aqueous liquid flow path 21 in the separator 20.

[0065] As described above, according to this embodiment, the control device 200 periodically drives the pump 100 even after power generation by the fuel cell 5 has stopped, to absorb eluted ions from the aqueous liquid stored in the aqueous liquid tank 106 before the aqueous liquid flows through the aqueous liquid flow path 21. This causes the aqueous liquid with the eluted ions absorbed to flow through the aqueous liquid flow path 21, periodically washing away the eluted ions, thereby further suppressing crevice corrosion of the aqueous liquid flow path 21 in the separator 20.

[0066] (Fifth embodiment) The fuel cell system 1 according to the fifth embodiment differs from the fuel cell system 1 according to the fourth embodiment in that it further includes an oxidant gas introduction valve 110 that connects the oxidant gas supply channel 41c and the aqueous liquid circulation channel 100c, and a drain valve 112 for the drain channel 100f of the aqueous liquid tank 106. The differences from the fuel cell system 1 according to the fourth embodiment will be described below.

[0067] 11 is a diagram showing an example of the overall configuration of a fuel cell system 1 according to a fifth embodiment. The fuel cell system 1 according to the fifth embodiment further includes an oxidant gas introduction valve 110 in an oxidant gas introduction channel 43c that connects an oxidant gas supply channel 41c and an aqueous liquid circulation channel 100c, a drain valve 112 in a drain channel 100f of the aqueous liquid tank 106, and a temperature sensor 206. A control unit 202 of the control device 200 controls the oxidant gas introduction valve 110 and the drain valve 112. The oxidant gas introduction channel 43c is a channel that branches off from the oxidant gas supply channel 41c downstream of the oxidant gas supply source and is connected to the aqueous liquid circulation channel 100c.

[0068] The temperature sensor 206 measures the environmental temperature where the fuel cell system 1 is placed. The temperature sensor 206 also supplies the control unit 202 with a temperature signal containing temperature information. Based on the temperature signal, the control unit 202 determines that there is a high risk of freezing when the outside air temperature where the fuel cell system 1 is placed falls below a predetermined threshold temperature. Alternatively, the control unit 202 predicts the outside air temperature based on the series values ​​of the outside air temperature, and determines that there is a high risk of freezing when the predicted value falls below the predetermined threshold temperature. In other words, the control unit 202 executes a purge process when the current outside air temperature or the predicted value falls below the predetermined threshold temperature. In this way, when the control unit 202 determines that there is a high risk of freezing, it executes a purge process to remove the aqueous liquid to prevent freezing.

[0069] (Control example) 12 is a time chart showing an example of control of the purge process in the control unit 202 according to the fifth embodiment. From the top, the chart shows changes over time in the power generation signal S1 of the fuel cell 5 output by the control unit 202, the freeze determination signal S5 of the control unit 202, the drive signal s6 of the drain valve 112, the drive signal s7 of the oxidant gas introduction valve 110, and the drive signal s8 for the oxidant supply source.

[0070] The power generation signal S1 remains at a low level, and power generation is stopped by the fuel cell 5. At time t10, the temperature of the temperature sensor 206 falls below the threshold temperature, and the control unit 202 sets the freeze determination signal s5 to a high level and starts purge process control.

[0071] At the same time as starting the purge process control, the control unit 202 changes the drive signal s6 of the drain valve 112 from low level to high level, changing the drain valve 112 from a closed state to an open state. This starts discharging the aqueous liquid from the aqueous liquid tank 106, the aqueous liquid circulation flow path 100c, the ion exchange resin flow path 100d, the circulation water path 100e, and the aqueous liquid flow path 21 via the drain path 100f of the aqueous liquid tank 106.

[0072] At time t11, the control unit 202 sets the drive signal s8 for the oxidant supply source to high level to start the supply of oxidant gas. Subsequently, at time t12, the control unit 202 sets the drive signal s7 for the oxidant gas introduction valve 110 to high level to change the oxidant gas introduction valve 110 from a closed state to an open state. As a result, the oxidant gas supplied from the oxidant supply source is introduced from the oxidant gas supply channel 41c via the oxidant gas introduction valve 110 into the aqueous liquid circulation channel 100c, the ion exchange resin channel 100d, the circulation water channel 100e, and the aqueous liquid channel 21. As a result, moisture remaining in the aqueous liquid circulation channel 100c, the ion exchange resin channel 100d, the circulation water channel 100e, and the aqueous liquid channel 21 after drainage is removed from the oxidant gas supply channel 41c via the oxidant gas introduction valve 110.

[0073] Next, at time t13, the control unit 202 sets the drive signal s8 to the oxidant supply source to low level, thereby stopping the supply of oxidant gas. The integrated value of the oxidant gas flowing through the aqueous liquid circulation channel 100c during the oxidant gas introduction period from time t12 to time t13 is three or more times the maximum capacity of the aqueous liquid circulation channel 100c, including the aqueous liquid channel 21. As a result, moisture in the aqueous liquid circulation channel 100c and the aqueous liquid channel 21 is sufficiently removed to prevent crevice corrosion.

[0074] Subsequently, at time t14, the control unit 202 sets the drive signal s7 for the oxidant gas introduction valve 110 to low level, thereby changing the oxidant gas introduction valve 110 from open to closed. Furthermore, at time t15, the control unit 202 sets the drive signal s6 for the drain valve 112 to low level, thereby changing the drain valve 112 from open to closed, thereby ending the purge process.

[0075] As described above, according to this embodiment, when the control unit 202 of the control device 200 determines that there is a high risk of freezing, it performs a purge process to remove the aqueous liquid to prevent freezing. During this process, the control unit 202 drains the aqueous liquid from the aqueous liquid tank 106, the aqueous liquid circulation channel 100c, the ion exchange resin channel 100d, the circulation water channel 100e, and the aqueous liquid channel 21 via the drain channel 100f of the aqueous liquid tank 106. After draining the aqueous liquid, the control unit 202 then circulates the oxidant gas from the oxidant gas supply channel 41c through the oxidant gas introduction valve 110 into the aqueous liquid circulation channel 100c, the ion exchange resin channel 100d, the circulation water channel 100e, and the aqueous liquid channel 21. This removes moisture from the aqueous liquid circulation channel 100c, the ion exchange resin channel 100d, the circulation water channel 100e, and the aqueous liquid channel 21, thereby preventing freezing and suppressing crevice corrosion in the aqueous liquid channel 21 in the separator 20.

[0076] (Modification of the first embodiment) The fuel cell system 1 according to the modification of the first embodiment differs from the fuel cell system 1 according to the first embodiment in that the aqueous liquid in the aqueous liquid circulation channel 100c is cooled via a secondary coolant heat exchanger 114. The differences from the fuel cell system 1 according to the first embodiment will be described below.

[0077] 13 is a diagram showing an example of the overall configuration of a fuel cell system 1 according to a modification of the first embodiment. The fuel cell system 1 according to the modification of the first embodiment differs from the fuel cell system 1 according to the first embodiment in that it includes a secondary coolant heat exchanger 114 instead of the radiator 102. That is, the fuel cell system 1 according to the modification of the first embodiment further includes the secondary coolant heat exchanger 114, a second radiator 116, a third pump 118, and a circulation water channel 200c.

[0078] The secondary coolant heat exchanger 114 cools the aqueous liquid flowing through the aqueous liquid circulation channel 100c by exchanging heat between the aqueous liquid flowing through the aqueous liquid circulation channel 100c and the aqueous liquid flowing through the circulation channel 200c. The second radiator 116 cools the aqueous liquid flowing through the circulation channel 200c. Furthermore, the third pump 118 circulates the aqueous liquid flowing through the circulation channel 200c under the control of the control unit 202. Note that the third pump 118 according to this embodiment corresponds to a third aqueous liquid delivery unit.

[0079] With this configuration, it is possible to use pure water or antifreeze liquid as the aqueous liquid flowing through the aqueous liquid circulation flow path 100c, and to use a less pure aqueous liquid as the aqueous liquid flowing through the circulation water path 200c. For example, when power generation by the fuel cell 5 is stopped, it is possible to make the freezing temperature lower than 0 degrees by supercooling the pure water or antifreeze liquid. On the other hand, since the aqueous liquid on the circulation water path 200c side does not flow through the fuel cell 5, the impact on the fuel cell 5 during discharge treatment, etc. can be suppressed.

[0080] (Modification of the second embodiment) The fuel cell system 1 according to the modified example of the second embodiment differs from the fuel cell system 1 according to the second embodiment in that the aqueous liquid in the aqueous liquid circulation channel 100c is cooled via a secondary coolant heat exchanger 114. The differences from the fuel cell system 1 according to the second embodiment will be described below.

[0081] 14 is a diagram showing an example of the overall configuration of a fuel cell system 1 according to a modification of the second embodiment. The fuel cell system 1 according to the modification of the second embodiment differs from the fuel cell system 1 according to the first embodiment in that it includes a secondary coolant heat exchanger 114 instead of the radiator 102. That is, the fuel cell system 1 according to the modification of the first embodiment further includes the secondary coolant heat exchanger 114, a second radiator 116, a third pump 118, and a circulation water channel 200c.

[0082] 13, this configuration allows pure water or antifreeze to be used as the aqueous liquid flowing through the aqueous liquid circulation channel 100c, and a lower purity aqueous liquid to be used as the aqueous liquid flowing through the circulation channel 200c. For example, when power generation by the fuel cell 5 is stopped, it is possible to reduce the freezing temperature to below 0°C by supercooling the pure water or antifreeze. On the other hand, because the aqueous liquid on the circulation channel 200c side does not flow through the fuel cell 5, the impact on the fuel cell 5 during discharge treatment, etc., can be reduced.

[0083] (Modification of the third embodiment) The fuel cell system 1 according to the modified example of the third embodiment differs from the fuel cell system 1 according to the third embodiment in that the aqueous liquid in the aqueous liquid circulation channel 100c is cooled via a secondary coolant heat exchanger 114. The differences from the fuel cell system 1 according to the second embodiment will be described below.

[0084] 15 is a diagram showing an example of the overall configuration of a fuel cell system 1 according to a modification of the third embodiment. The fuel cell system 1 according to the modification of the third embodiment differs from the fuel cell system 1 according to the first embodiment in that it includes a secondary coolant heat exchanger 114 instead of the radiator 102. That is, the fuel cell system 1 according to the modification of the first embodiment further includes the secondary coolant heat exchanger 114, a second radiator 116, a third pump 118, and a circulation water channel 200c.

[0085] 13, this configuration allows pure water or antifreeze to be used as the aqueous liquid flowing through the aqueous liquid circulation channel 100c, and a lower purity aqueous liquid to be used as the aqueous liquid flowing through the circulation channel 200c. For example, when power generation by the fuel cell 5 is stopped, it is possible to reduce the freezing temperature to below 0°C by supercooling the pure water or antifreeze. On the other hand, because the aqueous liquid on the circulation channel 200c side does not flow through the fuel cell 5, the impact on the fuel cell 5 during discharge treatment, etc., can be reduced.

[0086] (Modification of the fourth embodiment) The fuel cell system 1 according to the modification of the fourth embodiment differs from the fuel cell system 1 according to the fourth embodiment in that the aqueous liquid in the aqueous liquid circulation channel 100c is cooled via a secondary coolant heat exchanger 114. The differences from the fuel cell system 1 according to the second embodiment will be described below.

[0087] 16 is a diagram showing an example of the overall configuration of a fuel cell system 1 according to a modification of the fourth embodiment. The fuel cell system 1 according to the modification of the fourth embodiment differs from the fuel cell system 1 according to the first embodiment in that it includes a secondary coolant heat exchanger 114 instead of the radiator 102. That is, the fuel cell system 1 according to the modification of the first embodiment further includes the secondary coolant heat exchanger 114, a second radiator 116, a third pump 118, and a circulation water channel 200c.

[0088] 13, this configuration allows pure water or antifreeze to be used as the aqueous liquid flowing through the aqueous liquid circulation channel 100c, and a lower purity aqueous liquid to be used as the aqueous liquid flowing through the circulation channel 200c. For example, when power generation by the fuel cell 5 is stopped, it is possible to reduce the freezing temperature to below 0°C by supercooling the pure water or antifreeze. On the other hand, because the aqueous liquid on the circulation channel 200c side does not flow through the fuel cell 5, the impact on the fuel cell 5 during discharge treatment, etc., can be reduced.

[0089] (Modification of the fifth embodiment) The fuel cell system 1 according to the modification of the fifth embodiment differs from the fuel cell system 1 according to the fifth embodiment in that the aqueous liquid in the aqueous liquid circulation channel 100c is cooled via a secondary coolant heat exchanger 114. The differences from the fuel cell system 1 according to the second embodiment will be described below.

[0090] 17 is a diagram showing an example of the overall configuration of a fuel cell system 1 according to a modification of the fifth embodiment. The fuel cell system 1 according to the modification of the fifth embodiment differs from the fuel cell system 1 according to the first embodiment in that it includes a secondary coolant heat exchanger 114 instead of the radiator 102. That is, the fuel cell system 1 according to the modification of the first embodiment further includes the secondary coolant heat exchanger 114, a second radiator 116, a third pump 118, and a circulation water channel 200c.

[0091] 13, this configuration allows pure water or antifreeze to be used as the aqueous liquid flowing through the aqueous liquid circulation channel 100c, and a lower purity aqueous liquid to be used as the aqueous liquid flowing through the circulation channel 200c. For example, when power generation by the fuel cell 5 is stopped, it is possible to reduce the freezing temperature to below 0°C by supercooling the pure water or antifreeze. On the other hand, because the aqueous liquid on the circulation channel 200c side does not flow through the fuel cell 5, the impact on the fuel cell 5 during discharge treatment, etc., can be reduced.

[0092] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0093] 1: fuel cell system, 5: fuel cell, 13: anode electrode, 15: cathode electrode, 20: separator, 21: aqueous liquid flow path, 41c: oxidant gas supply flow path, 43c: oxidant gas introduction flow path, 100d: ion exchange resin flow path, 100f: drainage channel, 104: ion exchange resin bottle, 106: aqueous liquid tank, 110: oxidant gas introduction valve, 112: drainage valve, 200: control device, 202: control unit

Claims

1. a fuel cell that generates electricity by supplying a hydrogen-containing gas from a hydrogen supply source to a fuel electrode and introducing an oxygen-containing gas from an oxidizer gas supply source to an oxidizer electrode, and that has an aqueous liquid flow path therein through which an aqueous liquid that has the function of removing at least a portion of the heat generated by the power generation flows, the aqueous liquid flow path being entirely or partially made of a metal material; an aqueous liquid circulation flow path connected to the aqueous liquid flow path and capable of circulating the aqueous liquid; an aqueous liquid delivery unit that circulates the aqueous liquid in the aqueous liquid circulation flow path; a control unit that controls the aqueous liquid delivery unit, The control unit operates the aqueous liquid delivery unit at predetermined time intervals while the fuel cell is not generating electricity.

2. an ion exchange resin flow path that branches off from the aqueous liquid circulation flow path and returns the aqueous liquid to the aqueous liquid circulation flow path via an ion exchange resin bottle; 2. The fuel cell system according to claim 1, wherein the control unit starts flow through the ion exchange resin flow path in response to driving of the aqueous liquid delivery unit, and stops flow through the ion exchange resin flow path in response to stopping of driving of the aqueous liquid delivery unit.

3. 3. The fuel cell system of claim 2, wherein the control unit starts the flow of the ion exchange resin flow path either before or simultaneously with the start of operation of the aqueous liquid delivery unit, and stops the flow of the ion exchange resin flow path either after or simultaneously with the stop of operation of the aqueous liquid delivery unit.

4. a second aqueous liquid delivery section that circulates the aqueous liquid through the ion exchange resin flow path; 3. The fuel cell system according to claim 2, wherein the control unit starts and stops the flow of the ion exchange resin through the ion exchange resin flow path by controlling the second aqueous liquid delivery unit.

5. 5. The fuel cell system according to claim 1, wherein the integrated value of the flow rate during operation of the aqueous liquid delivery section for a predetermined period of time is three or more times the maximum capacity of the aqueous liquid circulation flow path including the aqueous liquid flow path.

6. a drainage flow path that connects the aqueous liquid circulation flow path to external drainage; A drain valve disposed in the drain flow path; an oxidant gas introduction flow path that branches off from the oxidant gas flow path downstream of the oxidant gas supply source and is connected to the aqueous liquid circulation flow path; an oxidant gas introduction valve disposed in the oxidant gas introduction channel, supplying the oxygen-containing gas from the oxidant gas supply source in accordance with an open state of the drain valve when the fuel cell system is not generating power; an oxidant gas introduction valve is opened in response to the supply of the oxygen-containing gas, and the oxygen-containing gas is circulated through the aqueous liquid circulation channel; After a predetermined time has elapsed in the open state, the supply of the oxygen-containing gas is stopped, in response to the stop of the supply of the oxygen-containing gas, closing the oxidant gas introduction valve; 6. The fuel cell system according to claim 5, wherein the drain valve is closed in response to the closure of the oxidant gas introduction valve.

7. 6. The fuel cell system according to claim 5, wherein an integrated value of the flow rate of the oxidant gas flowing into the aqueous liquid circulation channel during an oxidant gas introduction time during which the oxygen-containing gas is circulated through the aqueous liquid circulation channel is three times or more the maximum capacity of the aqueous liquid circulation channel including the aqueous liquid channel.

8. 8. The fuel cell system according to claim 6, wherein the control unit executes a series of control operations when the current or predicted value of the outside air temperature falls below a predetermined threshold temperature.

9. a fuel cell that generates electricity by supplying a hydrogen-containing gas from a hydrogen supply source to a fuel electrode and introducing an oxygen-containing gas from an oxidizer gas supply source to an oxidizer electrode, and that has an aqueous liquid flow path therein through which an aqueous liquid that has the function of removing at least a portion of the heat generated by the power generation flows, the aqueous liquid flow path being entirely or partially made of a metal material; an aqueous liquid circulation flow path connected to the aqueous liquid flow path and capable of circulating the aqueous liquid; an aqueous liquid delivery unit that circulates the aqueous liquid in the aqueous liquid circulation flow path; A control method for a fuel cell system comprising: A method for controlling a fuel cell system, comprising operating the aqueous liquid delivery section at predetermined time intervals while the fuel cell is not generating electricity.

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