JP2009134935A - Reaction water recovering structure of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reaction water recovering structure making reaction gas smoothly flow and capable of efficiently recovering reaction water. <P>SOLUTION: The reaction water recovering structure has an anode layer 11b formed on one surface of an electrolyte membrane 11a; a cathode layer 11c formed on the other surface of the electrolyte membrane 11a; a first separator 12 overlapped with one electrode layer 11b out of the anode layer and the cathode layer and having a first gas passage 12a supplying first reaction gas to the electrode layer 11b; and a second separator 13 having a cooling body 14 adjoined to the first separator 12 and through which a refrigerant flows, a second gas passage 13a overlapped with the other electrode layer 11c out of the anode layer and the cathode layer and supplying second reaction gas to the electrode layer 11c, and a condensed water production passage 13c continuing to the downstream side of the second gas passage 13a, overlapped with the cooling body 14, and capable of condensing moisture contained in the second reaction gas flowing through the second gas passage 13a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure for recovering produced water generated by a catalytic reaction of a fuel cell.

For example, the fuel cell of Patent Document 1 is provided with a post-reaction cathode gas flow path through which the cathode gas after the catalytic reaction flows, and after the reaction, liquid water is condensed in the cathode gas flow path to recover the reaction water.
JP 2005-285694 A

  However, in the above-described conventional fuel cell, the cathode gas channel width after the reaction region is narrower than the cathode gas channel width in the reaction region, and the cathode gas is difficult to flow. If the channel width of the cathode gas channel is increased after the reaction, the cathode gas channel is enlarged.

  The present invention has been made paying attention to such conventional problems, and an object of the present invention is to provide a reaction water recovery structure in which a reaction gas flows smoothly and reaction water can be recovered efficiently.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention provides an anode electrode layer (11b) provided on one surface of an electrolyte membrane (11a), a cathode electrode layer (11c) provided on the other surface of the electrolyte membrane (11a), and the anode A first separator (12) having a first gas channel (12a) that overlaps one electrode layer (11b) of the electrode layer and the cathode electrode layer and supplies a first reaction gas to the electrode layer (11b). And a cooling body (14) adjacent to the first separator (12) through which a refrigerant flows, and the other electrode layer (11c) of the anode electrode layer and the cathode electrode layer. A second gas flow path (13a) for supplying a second reactive gas to the layer (11c), and a second gas flow path that is continuous downstream of the second gas flow path (13a) and overlaps the cooling body (14). A condensed water generation flow path (13c) capable of condensing moisture contained in the second reaction gas flowing through (13a); And a second separator (13).

  According to this invention, it forms so that a cooling body may overlap with the condensed water production | generation flow path of a 2nd separator. The second reaction gas that has flowed through the second gas flow path contains moisture generated by the catalytic reaction of the electrode layer, and has a high temperature. Since the present invention has the above-described configuration, when the second reaction gas flows through the condensed water generation flow path, it is cooled by the refrigerant flowing through the cooling body, and moisture is condensed and collected in the pure water flow path. .

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a first embodiment of a reaction water recovery structure for a fuel cell according to the present invention.

  The fuel cell stack 1 has a configuration in which a plurality of power generation cells 10 are stacked and sandwiched between end plates 40 from both sides thereof.

  The power generation cell 10 is a unit cell of a fuel cell. Each power generation cell 10 generates an electromotive voltage of about 1 volt (V).

  The power generation cell 10 has a structure in which an anode separator 12 and a cathode separator 13 are laminated on the front and back surfaces of a membrane electrode assembly (hereinafter referred to as “MEA”) 11.

  The MEA 11 is provided with an anode electrode layer 11b (including a gas diffusion layer) on one surface of an electrolyte membrane 11a made of an ion exchange membrane, and a cathode electrode layer 11c (including a gas diffusion layer) on the other surface. . The MEA 11 is extremely thin and has a thickness of several tens of microns.

  The anode separator 12 overlaps the anode electrode layer 11b. In the anode separator 12, an anode gas flow path 12a for supplying an anode gas to the anode electrode layer 11b is formed on the surface facing the anode electrode layer 11b. A recess 12b through which pure water for humidifying the reaction gas flows is formed on the opposite surface. The anode separator 12 is a porous body. It is desirable that the gas pressure is always set higher than the water pressure. Further, it is desirable to subject the porous body to a hydrophilic treatment in order to facilitate the permeation of liquid water.

  The cathode separator 13 overlaps the cathode electrode layer 11c. In the cathode separator 13, a cathode gas flow path 13a for supplying a cathode gas to the cathode electrode layer 11c is formed on the surface facing the cathode electrode layer 11c. On the opposite surface, a recess 13b through which pure water for humidifying the reaction gas flows is formed. The cathode separator 13 is formed of a water-permeable porous body. It is desirable that the gas pressure is always set higher than the water pressure. The recess 12b of the anode separator 12 and the recess 13b of the cathode separator 13 form a pure water channel through which pure water flows.

  FIG. 2 is a view showing an anode separator, FIG. 2 (A) is a surface facing the anode electrode layer, and FIG. 2 (B) is a back surface thereof.

  The anode separator 12 has an anode gas channel 12a formed on the surface facing the anode electrode layer 11b. The anode gas flow path 12a overlaps the anode electrode layer 11b. The anode gas flowing in from the anode gas inlet manifold 21a flows through the anode gas flow path 12a and flows out from the anode gas outlet manifold 21b.

  In the anode separator 12, a pure water flow path 12 b through which pure water flows is formed on the surface opposite to the surface facing the anode electrode layer 11 b. In the present embodiment, the pure water passage 12b is a straight passage.

  A cooling body 14 is provided adjacent to the anode separator 12. As will be described later, the cooling body 14 cools the cathode gas that flows through the condensed water generation flow path 13c so as to overlap the condensed water generation flow path 13c. The cooling body 14 has substantially the same height (upper and lower length in FIG. 2) and thickness (depth length in FIG. 2) as the anode separator 12. The cooling body 14 may be integrally formed with the anode separator 12. The cooling water passage 14a through which the cooling water flows is formed between the cooling body 14 and the seal carrier. The cooling water channel 14a may be configured so that the cooling water does not flow out to the anode gas channel 12a and the cathode channel 13a. For example, the cooling body 14 may be formed by stacking two separators in the fuel cell stacking direction, and the cooling water flow path 14a may be configured between the separators. The cooling water flowing in from the cooling water inlet manifold 22a flows through the cooling water flow path 14a and flows out from the cooling water outlet manifold 22b. The cooling body 14 is formed of a dense material. The cooling body 14 is made of metal, for example. In addition, by placing a compression gasket such as normal silicon or rubber around the flow path side surface of one separator and sandwiching it with the other separator, reaction gas, cooling water, or pure water flows out of the flow path. Can be prevented. Moreover, in the separator formed with the porous body, the outflow from the porous body to the outside can be prevented by using a liquid gasket on the outer periphery of the separator.

  FIG. 3 is a view showing a cathode separator, FIG. 3 (A) is a surface facing the cathode electrode layer, and FIG. 3 (B) is a back surface thereof.

  The cathode separator 13 has a cathode gas channel 13a formed on the surface facing the cathode electrode layer 11c. The cathode gas flow path 13a overlaps the cathode electrode layer 11c. The cathode gas flows from the cathode gas inlet manifold 23a into the cathode gas flow path 13a.

  Further, in the cathode separator 13, a condensed water generation flow path 13c continues downstream of the cathode gas flow path 13a on the surface facing the cathode electrode layer 11c. The condensed water generation flow path 13 c overlaps the cooling body 14. The condensed water generation flow path 13c is a flow path for condensing moisture contained in the cathode gas flowing through the cathode gas flow path 13a. When the cathode gas flowing through the condensed water generation flow path 13c is cooled by the cooling body 14, the reaction water contained in the cathode gas is condensed. The condensed water production | generation flow path 13c of this embodiment changes the flow direction of cathode gas by a surface direction, as FIG. 3 (A) shows. That is, in FIG. 3A, the cathode gas flowing from the cathode gas flow path 13a once flows upward in FIG. 3A, then flows downward, flows upward again, and flows out from the cathode gas outlet manifold 23b. It has become. Thus, the condensed water production | generation flow path 13c is formed by a meandering flow path. Further, the condensed water generation channel 13c has a channel cross-sectional area smaller than that of the cathode gas channel 13a. With such a configuration, the gas flow rate of the condensed water generation flow path 13c is increased, and the condensed and grown droplets are easily separated by changing the flow path direction using the meandering flow path. Further, by providing a plurality of meandering channels, the number of times the droplet collides with the cathode separator 13 can be increased, the contact efficiency between the droplet and the cathode separator 13 can be improved, and the liquid water recovery efficiency can be improved. The permeation coefficient of the cathode separator 13 is larger in the portion of the condensed water generation passage 13c than in the portion of the cathode gas passage 13a (more specifically, the gas passage portion facing the electrochemical reaction surface (reaction region)). It is desirable to use a member that promotes the absorption of droplets. This is because the liquid water recovery efficiency is further improved and the fuel cell can be miniaturized.

  The cathode separator 13 is formed with a pure water flow path 13b through which pure water flows on the surface opposite to the surface facing the cathode electrode layer 11c. In the present embodiment, the pure water channel 13b is a straight channel. The pure water that has flowed in from the pure water inlet manifold 24a flows through the pure water passage 13b and flows out of the pure water outlet manifold 24b.

  FIG. 4 is a diagram for explaining the effect of the first embodiment, and corresponds to the IV-IV cross section of FIG.

  As described above, the anode gas flow path 12a of the anode separator 12 overlaps the anode electrode layer 11b of the MEA 11. A cooling body 14 is provided next to the anode separator 12. In the cathode separator 13, the cathode gas flow path 13a overlaps the cathode electrode layer 11c of the MEA 11, and the condensed water generation flow path 13c continues downstream of the cathode gas flow path 13a. The condensed water generation flow path 13 c of the cathode separator 13 overlaps the cooling body 14.

  The cathode gas that has flowed through the cathode gas flow path 13a contains moisture generated by the catalytic reaction of the cathode electrode layer 11c, and has a high temperature. Since the present embodiment has the above-described configuration, when the cathode gas flows through the condensed water generation flow path 13c, the cathode water is cooled by the cooling water (refrigerant) flowing through the cooling body 14, and moisture is condensed. In particular, the condensed water generation flow path 13c of the present embodiment changes the flow direction of the cathode gas in the plane direction as described above. Therefore, the cathode gas flowing through the condensed water generation flow path 13c collides with the wall surface of the condensed water generation flow path 13c every time the flow direction is changed, and is liable to adhere to the wall surface as liquid water. Since the cathode separator 13 is formed of a water-permeable porous body, the liquid water adhering to the wall surface moves to the pure water flow path 13b formed on the back surface of the condensed water generation flow path 13c, and the pure water flow It is collected in the path 13b.

  In the present embodiment, the flow direction of the cooling water flowing through the cooling body 14 is opposite to the flow direction of the cathode gas flowing through the cathode gas flow path 13a. Therefore, the cooling water can cool the cathode gas more efficiently and easily condense the liquid water. In this case, the reaction gas is exhausted to the cathode gas outlet manifold 23b through the gas diffusion layer provided on the catalyst in the MEA 11.

(Second Embodiment)
FIG. 5 is a plan view of a cathode separator showing a second embodiment of a reaction water recovery structure for a fuel cell according to the present invention.

  In the following description, parts having the same functions as those described above are denoted by the same reference numerals, and redundant description is omitted as appropriate.

  The condensed water generation flow path 13c of the cathode separator 13 of this embodiment is a straight flow path. And the flow-path obstruction | occlusion member 31 which obstruct | occludes the condensed water production | generation flow path 13c was provided in the downstream of the condensed water production | generation flow path 13c. The flow path closing member 31 is formed of a porous body having a hydrophilic surface.

  Since it has such a structure, the liquid water which flowed through the condensed water production | generation flow path 13c and condensed collides with the flow-path obstruction | occlusion member 31. FIG. And since the flow-path obstruction | occlusion member 31 is a hydrophilic porous body, the efficiency which traps liquid water improves and liquid water does not remain in a porous body. And it is guide | induced to the cathode separator 13 from the flow-path obstruction | occlusion member 31, moves to the pure water flow path 13b formed in the back surface of the condensed water production | generation flow path 13c, and is collect | recovered by the pure water flow path 13b.

(Third embodiment)
FIG. 6 is a view showing a third embodiment of the reaction water recovery structure for a fuel cell according to the present invention. FIG. 6 (A) is a plan view showing the side of the cathode separator facing the cathode electrode layer, and FIG. B) is a sectional view showing a laminated state.

  The condensed water generation flow path 13c of the cathode separator 13 of this embodiment is a straight flow path. And the flow-path obstruction | occlusion member 32 was provided in the downstream of the condensed water production | generation flow path 13c. Further, the rib height is lowered on the downstream side of the condensed water generation flow path 13c, and a porous body 33 having a hydrophobic surface is provided in this low portion.

  Since it has such a structure, the liquid water which flowed through the condensed water production | generation flow path 13c and condensed collides with the hydrophobic porous body 33, and carries out gas-liquid separation. Thus, by making the porous body 33 hydrophobic, liquid water can be easily filtered, and liquid water recovery efficiency can be further improved. And since it collides with the flow-path obstruction | occlusion member 32, it becomes easier to collect | recover the liquid water which flows out with cathode gas. Thus, volumetric efficiency and cost efficiency can be improved with a simple configuration.

  Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

  For example, in the above embodiment, the structure for recovering the moisture contained in the cathode gas is exemplified. However, if the cathode side / anode side configuration is reversed, the moisture contained in the anode gas can be recovered with the same configuration. .

  In the first embodiment, the condensed water generation flow path 13c is exemplified as a meandering flow path, but may be a straight flow path. Moreover, in 2nd Embodiment or 3rd Embodiment, although the condensed water production | generation flow path 13c was illustrated as a linear flow path, the meandering flow path like 1st Embodiment may be sufficient.

  Further, if the cross-sectional area of at least a part of the condensed water generation flow path 13c is made smaller than the cross-sectional area of the cathode gas flow path 13a, the flow velocity of the gas flowing through the condensed water generation flow path 13c increases, and the condensed growth occurs. Droplets can be more easily separated.

  Furthermore, if the permeation coefficient of the cathode separator 13 is made larger in the condensed water generation flow path 13c than in the cathode gas flow path 13a, the liquid water recovery efficiency and heat transfer rate can be further improved. The battery can be miniaturized. The magnitude of the permeability coefficient can be determined from the pore diameter range determined from the range of the gas-pure water maximum differential pressure to which the porous separator is exposed and the gas-pure water minimum differential pressure.

  Moreover, in the said embodiment, although the porous body is inserted, you may substitute the gas diffusion layer of MEA for this porous body.

  Furthermore, as shown in FIG. 7, the cooling water passage 14a may be formed so that the flow direction of the cooling water is orthogonal to the flow direction of the cathode gas. Specifically, the position of the cooling water inlet manifold 22a may be changed.

  Moreover, since it is desirable that the contact area of the cooling body 14 with respect to the condensed water production | generation flow path 13c is as large as possible, when it laminates | stacks, it is set as the structure where the cooling water passage 14a and the condensed water production | generation flow path 13c overlap as much as possible. desirable.

  In order to further improve the heat exchange efficiency and the reaction water recovery efficiency, it is desirable to increase the surface area of the gas flow path. Therefore, fins, unevenness, protrusions, and the like are preferably provided in the flow path.

  Furthermore, in the above-described embodiment, the cooling body 14 is directly stacked on the condensed water generation flow path 13c of the cathode separator 13, but a buffer material may be provided therebetween. If it does in this way, the contact area of the cooling body 14 and the cathode separator 13 will improve, and thermal conductivity will improve.

It is sectional drawing which shows 1st Embodiment of the reaction water collection | recovery structure of the fuel cell by this invention. It is a figure which shows an anode separator. It is a figure which shows a cathode separator. It is a figure explaining the effect of a 1st embodiment. It is a top view of the cathode separator which shows 2nd Embodiment of the reaction water collection | recovery structure of the fuel cell by this invention. It is a figure which shows 3rd Embodiment of the reaction water collection | recovery structure of the fuel cell by this invention. It is a figure explaining the modification of a cooling water channel.

Explanation of symbols

1 Fuel cell stack 10 Power generation cell 11 MEA
11a Electrolyte membrane 11b Anode electrode layer 11c Cathode electrode layer 12 Anode separator (first separator)
12a Anode gas channel (first gas channel)
12b Pure water flow path 13 Cathode separator (second separator)
13a Cathode gas flow path (second gas flow path)
13b Pure water flow path 13c Condensate water generation flow path 14 Cooling body 14a Cooling water path 31 Flow path closing member 32 Flow path closing member 33 Hydrophobic porous body (flow direction changing member)

Claims (8)

An anode electrode layer provided on one surface of the electrolyte membrane;
A cathode electrode layer provided on the other surface of the electrolyte membrane;
A first separator having a first gas flow path that overlaps one of the anode electrode layer and the cathode electrode layer and supplies a first reaction gas to the electrode layer;
A cooling body adjacent to the first separator and through which a refrigerant flows;
A second gas channel that overlaps the other electrode layer of the anode electrode layer and the cathode electrode layer and supplies a second reactive gas to the electrode layer; and the cooling body that is continuous downstream of the second gas channel. A second separator having a condensed water generation channel that can condense water contained in the second reaction gas that has flowed through the second gas channel;
A reaction water recovery structure for a fuel cell. The condensed water generation flow path is a flow path that changes a flow direction of the second reaction gas in a plane direction.
The reaction water recovery structure for a fuel cell according to claim 1. A flow path closing member formed in the condensed water generation flow path and closing at least a part of the condensed water generation flow path;
3. The reaction water recovery structure for a fuel cell according to claim 1, wherein the reaction water is recovered. The flow path blocking member is formed of a porous body having a hydrophilic surface.
The reaction water recovery structure for a fuel cell according to claim 3. A flow direction changing member that is formed in the condensed water generation flow path and changes the flow direction of the second reaction gas in the stacking direction;
The reaction water recovery structure for a fuel cell according to any one of claims 1 to 4, wherein The flow direction changing member is formed of a hydrophobic porous body.
The reaction water recovery structure for a fuel cell according to claim 5. A flow path cross-sectional area of at least a part of the condensed water generation flow path is smaller than a flow path cross-sectional area of the second gas flow path,
The reaction water recovery structure for a fuel cell according to any one of claims 1 to 6, wherein The permeation coefficient of the second separator is larger in the condensed water generation flow path than in the second gas flow path.
The reaction water recovery structure for a fuel cell according to any one of claims 1 to 7, wherein

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