JP2004207106A - Solid polymer fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid polymer fuel cell stack with simple structure, low price, making miniaturization possible, preventing the blocking of a passage caused by the entrance of dew formation moisture in a gas passage for reaction gas flow, and uniformly generating electric power in each cell. <P>SOLUTION: The fuel cell stack 20A is formed in such a way that the stack is formed by stacking many cells 11 each comprising an air electrode, a solid polymer electrolyte membrane, and a fuel electrode through a pair of separators 10 in which reaction gas flows from a top side 18 to a lower side through the gas passage 8, and a supply manifold 1 for distributing and supplying the reaction gas to each cell of the stack is installed in the upper part of the gas passage 8, and at least the manifold 1 is declined in the stacking direction and/or in the direction forming a right angle with the stacking direction, the dew formation moisture at least in the supply manifold 1 is drained along the declination and exhausted to the outside through a flow exhausting means. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polymer electrolyte fuel cell stack, and more specifically, to prevent a case in which dewed moisture enters a gas flow path for reactant gas flow to block a flow path or increase flow resistance. The present invention relates to a high-performance polymer electrolyte fuel cell stack capable of preventing power generation, generating uniform power in each cell, and obtaining a uniform electromotive force.
[0002]
[Prior art]
FIG. 4 is an exploded sectional view showing a basic configuration of an electrode (cell) of a polymer electrolyte fuel cell, which is one form of a conventional fuel cell. An air electrode (cathode) side catalyst layer 2 and a fuel electrode (anode) side catalyst layer 3 each containing a noble metal (mainly platinum) are joined to the main surfaces on both sides of the solid polymer electrolyte membrane 1, respectively. An air electrode-side gas diffusion layer 4 and a fuel electrode-side gas diffusion layer 5 are disposed to face the fuel electrode 2 and the fuel electrode side catalyst layer 3, respectively. Thereby, an air electrode 6 and a fuel electrode 7 are respectively formed. These gas diffusion layers 4 and 5 serve to transmit an oxidizing gas and a fuel gas, respectively, and to transmit a current to the outside. A conductive gas flow path 8 is provided on the outer surfaces of the gas diffusion layers 4 and 5 facing the gas diffusion layers 4 and 5, and a cooling water flow path 9 for cooling water flow is provided on the opposite main surface. And a pair of separators 10 made of a gas-impermeable material, and sandwiching the electrolyte membrane 1, the catalyst layers 2, 3, and the gas diffusion layers 4, 5 by clamping them. (Cell).
[0003]
FIG. 5 is a cross-sectional view showing a basic configuration of a polymer electrolyte fuel cell stack (stack). The polymer electrolyte fuel cell stack 20 is formed by stacking a large number of fuel cell electrodes 11 (cells), applying a current collector plate 12, an insulating plate 13 for electric and thermal insulation, and applying a load to the stack. It is clamped by a clamping plate 14 for holding, and is clamped by a bolt 15 and a nut 17, and a clamping load is applied by a disc spring 16. Reference numeral 18 denotes the top side of the polymer electrolyte fuel cell stack 20.
[0004]
The solid polymer electrolyte membrane 1 has a proton exchange group in the molecule, and when the water content is saturated, the specific resistance becomes 20 Ωcm ² or less at room temperature, and functions as a proton conductive electrolyte. As described above, the solid polymer electrolyte membrane 1 functions as a proton conductive electrolyte by being hydrated. In the polymer electrolyte fuel cell, the reaction gas is saturated with water vapor so that each fuel cell electrode 11 The method of supplying and operating is adopted.
[0005]
When a fuel gas containing hydrogen is supplied to the fuel electrode 7 and an oxidizing gas containing oxygen is supplied to the air electrode 6, the fuel electrode 7 decomposes hydrogen molecules into hydrogen ions and electrons at the fuel electrode 7. The following electrochemical reactions that generate water from hydrogen ions and electrons are performed, and power is supplied to the load by electrons moving through the external circuit from the fuel electrode to the air electrode, and water is generated on the air electrode side Will be done.
[0006]
Fuel ^{_{electrode; H 2 → 2H + + 2e}} - ( anode reaction)
Air electrode; 2H ⁺ + (1/2) O ₂ + 2e ⁻ → H ₂ O (air electrode reaction)
Whole; H ₂ + (１ ／) O ₂ → H ₂ O
[0007]
For example, as shown in FIG. 6, an internal manifold I for supplying a reactive gas is formed on the top surface 18 of the separator 10 in communication with the gas flow path 8 for flowing the reactive gas, and a gas is supplied to an end of the manifold I. A port J is provided, and a gas discharge manifold K is formed at the other end in communication with each gas flow path 8, and a gas discharge port L is provided at an end of the manifold. Accordingly, the reactant gas flows into the internal manifold I from the gas supply port J via the first reactant gas supply manifold provided in the stacking direction of the fuel cell (not shown). The gas flows downward into the gas discharge manifold K, and passes through the gas discharge manifold K through the gas discharge port L in the stacking direction of a fuel cell (not shown). After that, it is discharged outside.
[0008]
In another separator 10, for example, as shown in FIG. 7, an external manifold I for supplying a reactive gas separately prepared and mounted on the top surface 18 is formed in a state of being communicated with the gas flow path 8 for flowing a reactive gas. Other than that, it is the same as the separator 10 shown in FIG.
[0009]
Conventionally, when water enters the manifold, water is received in a concave portion provided in the manifold so that the water does not flow into the reaction gas distribution gas flow path (see Patent Document 1). A guide plate is provided below the gas manifold provided to supply the reaction gas to the cell stack, and the bottom of the gas manifold is inclined, and the liquid containing phosphoric acid is guided by the inclination of the guide plate and the bottom of the gas manifold. A proposal for preventing dielectric breakdown and corrosion by discharging the gas to the outside (see Patent Document 2), and tightening the stack in the internal manifold so that the reaction gas flows uniformly from the manifold to each gas flow channel for flowing the reaction gas. There is a proposal to provide a rectifying member for a reaction gas made of a cylindrical or columnar penetrating material that also functions as an integrated tie rod (see Patent Document 3).
[0010]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 05-129031 [Patent Document 2]
Japanese Patent Application Laid-Open No. 05-251106 [Patent Document 3]
JP 2002-252021 A
[Problems to be solved by the invention]
However, in the conventional fuel cell stack, a supply manifold I for distributing / supplying the reaction gas to each cell is provided on the top side 18 of the fuel cell stack 20 and above the gas flow path 8 so that the reaction gas is In the case of a configuration in which the gas flows downward from the side 18 through the gas supply port J to the supply manifold I in the gas flow path 8, the moisture in the humidified reaction gas is condensed inside the supply manifold I and condensed. There is a problem that moisture enters the gas flow path 8 and closes the gas flow path 8 or raises the flow resistance. When the gas flow path 8 is closed or the flow resistance increases, the flow of the reactant gas increases. There is a problem that the power generation in the cells becomes uneven, whereby the power generation in each cell becomes uneven, and the electromotive force varies, thereby deteriorating the performance of the fuel cell.
An object of the present invention is to provide a reaction gas distribution gas flow path in which water condensed in a supply manifold provided on a top surface side of a fuel cell stack blocks a flow path or increases flow path resistance. To provide a high-performance polymer electrolyte fuel cell stack that can easily prevent the occurrence of a reaction gas, make the flow of the reaction gas uniform, generate power uniformly in each cell, and obtain a uniform electromotive force. That is.
[0012]
[Means for Solving the Problems]
The polymer electrolyte fuel cell stack according to claim 1 of the present invention for solving the above-mentioned problems is characterized in that a cell composed of an air electrode, a solid polymer electrolyte membrane, and a fuel electrode is formed by reacting gas from the top side. A stack is formed by laminating a large number through a set of separators flowing downward in a gas flow path, and a supply manifold for distributing and supplying a reaction gas to each cell of the stack is provided in the gas flow path. In the fuel cell stack provided above,
At least the supply manifold is inclined in a stacking direction of the fuel cell and / or in a direction perpendicular to the stacking direction, and a discharge means for flowing at least water condensed in the supply manifold along the slope and discharging the water to the outside is provided. It is characterized by.
[0013]
In the polymer electrolyte fuel cell stack of the present invention, the supply manifold for distributing / supplying the reaction gas to each cell is installed on the top surface side of the fuel cell stack at an angle, so that the water vapor in the reaction gas is reduced. Even if condensation occurs in the supply manifold, the condensed water flows along the slope and is discharged to the outside via the discharge means, and the condensed water enters the reaction gas flow gas flow path and is blocked. In addition, it is possible to easily prevent the flow path resistance from increasing, and to uniformly distribute and supply the reaction gas to each cell, to uniformly generate power in each cell, and to obtain a uniform electromotive force.
It is also possible to provide the supply manifold with the inclination by arranging the polymer electrolyte fuel cell stack of the present invention inclining in the fuel cell stacking direction and / or the direction perpendicular to the stacking direction.
[0014]
A polymer electrolyte fuel cell stack according to a second aspect of the present invention is the polymer electrolyte fuel cell stack according to the first aspect, wherein the supply manifold is an internal manifold.
[0015]
Since the internal manifold can be easily formed at the time of forming the separator, the cost can be reduced, the structure can be simplified, and the size can be reduced.
[0016]
A solid polymer electrolyte fuel cell stack according to a third aspect of the present invention is the solid polymer electrolyte fuel cell stack according to the first aspect, wherein the supply manifold is an external manifold.
[0017]
If an external manifold is prepared separately from the separator, it can be attached to a laminate using various separators and applied, which is simple.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(1) FIG. 1 is an explanatory view schematically showing one embodiment of a supply manifold for a polymer electrolyte fuel cell stack according to the present invention.
In FIG. 1, the same components as those shown in FIGS. 4 to 7 are denoted by the same reference numerals, and redundant description will be omitted.
In the polymer electrolyte fuel cell stack 20A of the present invention, a supply manifold I for distributing and supplying a reaction gas to each cell 11 of the stack 20A is provided above the gas flow path 8. The supply manifold I is provided at an angle θ with respect to a horizontal plane Y in the stacking direction X of the fuel cell. 21A and 21B are means for discharging condensed moisture provided on both sides of the end of the supply manifold I which is inclined.
[0019]
The angle θ is not particularly limited, but is preferably about 3 ° or more, because the dewed water is easily discharged. The upper limit of the angle θ is preferably an angle that does not impair the stability of the polymer electrolyte fuel cell stack 20A of the present invention and does not adversely affect contact with other members.
[0020]
Although not shown, the portion of the polymer electrolyte fuel cell stack 20A of the present invention below the supply manifold I is configured as shown in FIGS. 4 and 5 corresponding to the supply manifold I provided at an angle. Are provided as well. Even if dew condensation occurs in the supply manifold I provided at an angle or in the vicinity of the gas supply port J, the condensed moisture 22 flows down the inner wall and the like, flows to the lower part of the supply manifold I, and is discharged to the outside via the discharge means 21A and 21B. Is discharged.
[0021]
The discharging means 21A, 21B may be formed by an appropriate pipe line, and an airtight opening / closing valve such as a solenoid valve is provided at a key point thereof. When there is water to be discharged, the valve is opened. Can be put closed.
[0022]
By providing the supply manifold I with an inclination, it is possible to easily prevent the dewed moisture from entering the reaction gas flowing gas flow path 8 and closing the flow path 8 or increasing the flow resistance. By uniformly distributing and supplying the reaction gas to each cell, uniform power generation can be performed in each cell, and a uniform electromotive force can be obtained.
[0023]
In the present invention, the polymer electrolyte fuel cell stack 20A of the present invention is provided at an angle θ with respect to the horizontal plane Y in the stacking direction X of the fuel cell, so that the supply manifold I is The angle θ may be inclined in the direction X with respect to the horizontal plane Y.
[0024]
When the polymer electrolyte fuel cell stack 20A of the present invention is provided at an angle θ with respect to the horizontal plane Y in the stacking direction X of the fuel cell, only the moisture condensed in the supply manifold I and near the gas supply port J is provided. Instead, the first reaction gas supply manifold provided in the gas discharge manifold K and the vicinity of the gas outlet L in the direction of stacking of the fuel cell (not shown), and the like, and the stacking direction of fuel cell (not shown) The second manifold for gas discharge penetrated through the pipe, moisture condensed in other pipes through which gas passes, etc., can be easily discharged to the outside by providing appropriate discharge means. An increase in resistance can be prevented.
[0025]
(2) FIG. 2 is an explanatory view schematically showing another embodiment of the supply manifold of the polymer electrolyte fuel cell stack according to the present invention.
In FIG. 2, the same components as those shown in FIGS. 1 and 4 to 7 are denoted by the same reference numerals, and redundant description may be omitted.
In the polymer electrolyte fuel cell stack 20B of the present invention, the supply manifold I is provided at an angle θ with respect to a horizontal plane Y in a direction perpendicular to the stacking direction X of the fuel cells. 21A and 21B are means for discharging condensed moisture provided on both sides of the end of the supply manifold I which is inclined.
[0026]
Although the portion below the supply manifold I of the polymer electrolyte fuel cell stack 20B of the present invention is not shown, it is configured as shown in FIGS. 4 and 5 corresponding to the supply manifold I provided at an angle. Are provided as well.
[0027]
Even if dew condensation occurs in the supply manifold I provided at an angle or in the vicinity of the gas supply port J, the condensed moisture 22 flows down the inner wall and the like, flows to the lower part of the supply manifold I, and is discharged to the outside via the discharge means 21A and 21B. Is discharged. By providing the supply manifold I with an inclination, it is possible to easily prevent the dewed moisture from entering the reaction gas flowing gas flow path 8 and closing the flow path 8 or increasing the flow resistance. By uniformly distributing and supplying the reaction gas to each cell, uniform power generation can be performed in each cell, and a uniform electromotive force can be obtained.
[0028]
In the present invention, the polymer electrolyte fuel cell stack 20B of the present invention is provided at an angle θ with respect to a horizontal plane Y in a direction perpendicular to the stacking direction X of the fuel cell, so that the supply manifold I The battery may be inclined at an angle θ with respect to a horizontal plane Y in a direction perpendicular to the battery stacking direction X.
[0029]
When the polymer electrolyte fuel cell stack 20B of the present invention is provided at an angle θ with respect to the horizontal plane Y in a direction perpendicular to the stacking direction X of the fuel cell, dew condensation occurs in the supply manifold I and near the gas supply port J. In addition to the moisture, the first reactant gas supply manifold, which is provided in the gas discharge manifold K and the vicinity of the gas outlet L in the stacking direction of the fuel cell (not shown), and the like, and the fuel cell (not shown) The second manifold for gas discharge penetrated in the laminating direction of the above, moisture condensed in other pipes through which gas passes can be easily discharged to the outside by providing appropriate discharge means, and the flow path is blocked. And an increase in channel resistance can be prevented.
[0030]
The angle θ is not particularly limited, but is preferably about 3 ° or more, because the dewed water is easily discharged. The upper limit of the angle θ is preferably an angle that does not impair the stability of the polymer electrolyte fuel cell stack 20B of the present invention and does not adversely affect contact with other members.
[0031]
(3) FIG. 3 is an explanatory view schematically showing only the bottom of another supply manifold of the polymer electrolyte fuel cell stack of the present invention.
In FIG. 3, the same components as those shown in FIGS. 1 to 7 are denoted by the same reference numerals, and redundant description will be omitted.
Another supply manifold of the polymer electrolyte fuel cell stack according to the present invention includes a supply manifold I (FIG. 3 shows only a top surface or a bottom surface of the supply manifold I) on a horizontal plane Y in a stacking direction X of the fuel cell. In addition, the fuel cell is inclined by an angle θ1 and is inclined by an angle θ2 with respect to a horizontal plane Y in a direction Z perpendicular to the stacking direction X of the fuel cell. W indicates the vertical direction.
Even if dew condensation occurs in the supply manifold I provided in such an inclined manner or in the vicinity of the gas supply port J, the condensed water flows through the inner wall and the like, flows to the lower part of the supply manifold I, and passes through one discharge means to the outside. Can be discharged.
[0032]
The angle θ1 and the angle θ2 are not particularly limited. However, it is usually preferable that both angles are about 3 ° or more because the dewed water is easily discharged. The upper limits of the angles θ1 and θ2 may be the same or different as long as the stability of the polymer electrolyte fuel cell stack of the present invention is not impaired and the angle does not adversely affect contact with other members. It is preferable that the angle be determined at an optimum angle in consideration of the size of the polymer electrolyte fuel cell stack of the present invention, the state of the installation place, the ease of drainage, and the like.
[0033]
The polymer electrolyte fuel cell stack of the present invention is inclined at an angle θ1 with respect to a horizontal plane Y in the stacking direction X of the fuel cell, and at an angle θ2 with respect to the horizontal plane Y in a direction Z perpendicular to the stacking direction X of the fuel cell. When the fuel cell is not tilted, not only the moisture condensed in the supply manifold I and the vicinity of the gas supply port J, but also the moisture condensed in the gas discharge manifold K and the vicinity of the gas discharge port L, and other layers of a fuel cell (not shown) Reaction gas supply manifold provided through the fuel cell, a second gas discharge manifold provided through the fuel cell (not shown) in the stacking direction, moisture condensed in other pipes through which gas passes, and the like. Also, by providing appropriate discharge means, it is easy to discharge to the outside, and it is possible to prevent flow path blockage and increase in flow path resistance.
[0034]
The description of the above embodiments is for describing the present invention, and does not limit the invention described in the claims or reduce the scope thereof. Further, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.
[0035]
【The invention's effect】
In the polymer electrolyte fuel cell stack according to claim 1 of the present invention, a cell composed of an air electrode, a solid polymer electrolyte membrane, and a fuel electrode is formed so that a reaction gas flows downward from a top surface in a gas flow path. A fuel cell comprising a stack formed by laminating a large number of components via a set of flowable separators, and a supply manifold for distributing and supplying a reaction gas to each cell of the stack above the gas flow path. In the stack, at least the supply manifold is inclined in a stacking direction of the fuel cell and / or in a direction perpendicular to the stacking direction, and at least a discharge means for flowing at least water condensed in the supply manifold along the slope and discharging the water to the outside. Even if water vapor in the reaction gas condenses in the supply manifold, the condensed water flows along the slope and is discharged to the outside via the discharge means. It is possible to easily prevent the condensed water from entering the reactant gas flow gas passage and blocking the passage or increasing the passage resistance, and distribute the reactant gas uniformly to each cell. -It has a remarkable effect that uniform power generation can be performed in each cell by supply, uniform electromotive force can be obtained, the structure is simple, inexpensive, and miniaturization is possible.
It is also possible to provide the supply manifold with the inclination by arranging the polymer electrolyte fuel cell stack of the present invention inclining in the fuel cell stacking direction and / or the direction perpendicular to the stacking direction.
[0036]
The polymer electrolyte fuel cell stack according to claim 2 of the present invention is the polymer electrolyte fuel cell stack according to claim 1, wherein the supply manifold is an internal manifold. Since the internal manifold can be easily formed at the time of producing the separator, the cost can be reduced, the structure is simple, and the size can be further reduced.
[0037]
A polymer electrolyte fuel cell stack according to claim 3 of the present invention is the polymer electrolyte fuel cell stack according to claim 1, wherein the supply manifold is an external manifold. If an external manifold is prepared separately from the production of the separator, the external manifold can be applied to a laminate using various separators, and a further remarkable effect of simplicity can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory view schematically showing one embodiment of a supply manifold of a polymer electrolyte fuel cell stack according to the present invention.
FIG. 2 is an explanatory view schematically showing another embodiment of a supply manifold of the polymer electrolyte fuel cell stack according to the present invention.
FIG. 3 is an explanatory view schematically showing another embodiment of the supply manifold of the polymer electrolyte fuel cell stack according to the present invention.
FIG. 4 is an exploded cross-sectional view showing a basic configuration of an electrode (cell) of a polymer electrolyte fuel cell which is one form of a conventional fuel cell.
FIG. 5 is a cross-sectional view showing a basic configuration of a polymer electrolyte fuel cell stack (stack).
FIG. 6 is an explanatory sectional view of a separator having an internal manifold.
FIG. 7 is an explanatory cross-sectional view of a separator having an external manifold.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 solid polymer electrolyte membrane 2 air electrode (cathode) side catalyst layer 3 fuel electrode (anode) side catalyst layer 4 air electrode side gas diffusion layer 5 fuel electrode side gas diffusion layer 6 air electrode 7 fuel electrode 8 reaction gas distribution gas Channel 9 Cooling water channel 10 Separator 11 Electrode (cell) for fuel cell
18 Top side 20, 20A, 20B Solid polymer fuel cell stacks 21A, 21B Discharge means 22 Condensed moisture I Supply manifold J Gas supply port K Gas discharge manifold L Gas discharge port X Stacking direction Y Horizontal plane Z Stacking direction And the direction W perpendicular to the vertical angle θ, θ1, θ2 Angle

Claims (3)

By stacking a large number of cells composed of an air electrode, a solid polymer electrolyte membrane, and a fuel electrode through a set of separators in which the reaction gas flows downward from the top surface in the gas flow path, a stack is formed. In a fuel cell stack formed by providing a supply manifold for distributing and supplying a reaction gas to each cell of the stack above the gas flow path,
At least the supply manifold is inclined in a stacking direction of the fuel cell and / or in a direction perpendicular to the stacking direction, and a discharge unit is provided for flowing at least water condensed in the supply manifold along the slope and discharging the water to the outside. A polymer electrolyte fuel cell stack characterized by the above-mentioned. 2. The polymer electrolyte fuel cell stack according to claim 1, wherein the supply manifold is an internal manifold. 2. The polymer electrolyte fuel cell stack according to claim 1, wherein the supply manifold is an external manifold.

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