JP4177291B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell. More specifically, the separator can be cooled using the heat of vaporization of generated water, and flooding in a reaction channel can be prevented by smoothly draining the generated water. The present invention relates to a fuel cell system.

A fuel cell directly converts chemical energy into electrical energy by supplying fuel and an oxidant to two electrically connected electrodes and causing the fuel to be oxidized electrochemically. Unlike thermal power generation, it is not subject to the Carnot cycle, so it exhibits high energy conversion efficiency. A solid polymer electrolyte fuel cell is a fuel cell that uses a solid polymer electrolyte membrane as an electrolyte, and has advantages such as easy miniaturization and operation at a low temperature. It is attracting attention as a power source for the body.
In a solid polymer electrolyte fuel cell, two sides of a membrane-electrode assembly having a fuel electrode on one side of the polymer electrolyte membrane and an oxidant electrode on the other side are also used as current collectors. A single cell is formed by being sandwiched by a separator. Usually, a fuel gas flow path is formed on the side of the fuel electrode side separator in contact with the fuel electrode, and a reaction flow path is formed on the side of the oxidant electrode side separator in contact with the oxidant electrode.

The fuel electrode to which the fuel gas is supplied includes a fuel electrode side gas diffusion layer and a fuel electrode side catalyst layer. When hydrogen is used as the fuel gas, the reaction of the formula (1) proceeds. At this time, the electrons generated in the equation (1) reach the oxidant electrode after working with an external load via the external circuit.
H ₂ → 2H ⁺ + 2e ⁻ (1)
The proton generated in the formula (1) moves in the polymer electrolyte membrane from the fuel electrode side to the oxidant electrode side by electroosmosis in a state of being hydrated with water.
The oxidant electrode to which the oxidant gas is supplied includes an oxidant electrode side gas diffusion layer and an oxidant electrode side catalyst layer. When the oxidant gas is an oxygen-containing gas, the formula (2) The reaction proceeds.
2H ⁺ + (1/2) O ₂ + 2e ⁻ → H ₂ O (2)
A part of the water generated at the oxidizer electrode is diffused back toward the fuel electrode due to the concentration gradient, but most of the remaining water is discharged outside the fuel cell.

  In general, in the oxidizer electrode, there is a tendency that water is excessively present because water is transferred from the fuel electrode by electroosmosis and water is generated in the oxidizer electrode by electrode reaction. If the amount of water becomes excessive, so-called flooding occurs in which water vapor condenses in the porous oxidant electrode side gas diffusion layer and closes the pores, hindering gas permeation of the oxidant electrode side gas diffusion layer. Therefore, the oxidant gas does not reach the oxidant electrode side catalyst layer, and the power generation efficiency decreases. Therefore, it is necessary to efficiently discharge water from the oxidant electrode side.

  In addition, even on the same oxidizer electrode side, the excess / deficiency state of water differs between upstream and downstream of the gas flow path. Since the downstream oxidant gas is humidified by the water generated on the upstream side, it contains more water than the upstream oxidant gas. Therefore, the amount of moisture may be insufficient on the upstream side even in the oxidant gas flow path. Accordingly, it is important to perform appropriate humidification on the upstream side while preventing the occurrence of flooding on the downstream side even in the oxidant gas flow path.

  As a drainage method for preventing flooding due to generated water, Japanese Patent Application Publication No. 11-508726 discloses that a porous plate is interposed between an oxidant gas flow path and a cooling water path to generate the oxidant gas flow path. A technique for discharging water into a cooling channel by pressure control is described. However, this technique does not consider humidifying the upstream side of the oxidant gas flow path for generating the generated water using the generated water.

  In Japanese Patent Laid-Open No. 9-283157, a separator made of a conductive thin plate having a large number of through holes is provided with irregularities, and an oxidant gas flow path and a fuel gas are formed in a space formed between the separator and the unit cell. A technology for draining the generated water in the oxidant gas flow path to the fuel gas flow path through the through hole by forming the flow path adjacently and sealing the through hole with a water-permeable and air-impermeable resin. Are listed. Although this technology enables humidification of the fuel gas flow path at the same time as drainage, the vaporization rate from the through hole is slow, and moisture may accumulate in the resin sealing the through hole, causing flooding. . Further, although this technique humidifies the fuel gas flow path, it does not consider that the upstream side of the oxidant gas flow path that generates the generated water is humidified using the generated water.

In JP-A-6-68884, a cooling water distribution plate provided with a cooling water flow path and a porous humidified water transmission plate are combined to form a cooling plate, and the porous water is passed through the humidified water transmission plate. A technique for humidifying a fuel gas flow path using cooling water by laminating on a fuel flow plate is described. However, this technique has a small amount of vaporization and cannot always perform sufficient humidification.
Further, this technique performs humidification using cooling water, and does not take into consideration humidification using generated water on the upstream side of the oxidant gas flow path for generating generated water.

The power generation process is an exothermic reaction as a whole, and the operating temperature of the solid polymer electrolyte fuel cell is normally limited to about 70-80 ° C. Therefore, the fuel cell is cooled by some cooling means. It is necessary to.
Japanese National Patent Publication No. 11-508726 JP-A-9-283157 JP-A-6-68884

  An object of the present invention is to provide a fuel cell system that can cool a battery system by effectively using generated water accompanying power generation of a fuel cell and can prevent flooding in a reaction channel. .

  The inventors of the present invention form a part or the whole of the electrode-side separator that generates generated water with a porous body, and the reaction gas channel on the electrode side is divided into an upstream cooling channel and a downstream reaction channel. The cooling channel is arranged on the adjacent cell side surface of the separator, the reaction channel is arranged on the electrode side surface of the separator, and the upstream end of the reaction channel is connected to the downstream end of the cooling channel. A fuel cell was fabricated, and an experiment was conducted in which the generated water and humidified water in the electrode or the reaction channel are permeated to the cooling channel through the porous body portion of the separator and vaporized there. According to the results of this experiment, the fuel cell was operated under the condition that a constant amount of air per unit time flows through a reaction gas channel having a cooling channel on the upstream side and a reaction channel on the downstream side. When the generated water discharged from the electrode through the reaction is permeated toward the cooling channel through the porous body adjacent to the electrode, the surface area of the cooling channel and the evaporation of the generated water to the air flowing through the cooling channel The relationship with the quantity is roughly as shown in FIG. The relationship between the cross-sectional area of the cooling channel and the evaporation amount is approximately as shown in FIG. 2, and the relationship between the density of the porous body and the evaporation amount is approximately as shown in FIG.

From the above results, the following knowledge was obtained and the present invention was completed.
(1) The larger the surface area of the cooling channel, the more the amount of evaporation into the cooling channel.
(2) The smaller the channel cross-sectional area of the cooling channel, the larger the amount of evaporation into the cooling channel, that is, the faster the air flow rate, the larger the amount of evaporation.
(3) When the thermal conductivity of the porous body is high, the vaporization heat is supplied quickly and the amount of evaporation into the cooling channel is large.

  Based on these matters, in order to solve the above problems, a fuel cell system of the present invention includes a cell having electrodes disposed on both sides of an electrolyte, and a separator disposed further outside the electrode. A fuel cell system comprising at least one, wherein a part of the separator is formed of a porous body, and is disposed on a surface of the porous body in contact with the electrode of the porous body, and a reactive gas is supplied to the electrode. And a cooling channel that is disposed inside the porous body and allows a cooling gas having a lower humidity than the reaction gas flowing through the reaction channel to flow therethrough.

  According to this fuel cell system, since the entire periphery of the cooling flow path is a porous body, the generated water discharged from the electrode penetrates into the porous body adjacent to the electrode and moves toward the cooling flow path. The surface area of the cooling channel that can enter the cooling channel from all directions around the cooling channel and is effective in vaporizing water is increased. Therefore, the amount of water vaporized into the cooling channel increases, and the fuel cell can be cooled using the heat of vaporization. And since generated water is efficiently discharged | emitted from the area | region of a reaction flow path, flooding can be prevented.

It is preferable that the cooling gas flowing through the cooling channel and the reaction gas adjacent to the cooling channel are the same gas. In this case, there is no concern that an interaction such as a chemical reaction between the cooling gas and the reaction gas occurs through the porous body.
Further, the gas in the cooling flow path is humidified by the vaporization. Therefore, by using the humidified cooling gas as the reaction gas, the fuel cell itself can be used for power generation. In particular, it is preferable that the cooling gas and the reaction gas are the same type of gas, and the cooling gas is used as a humidified reaction gas as it is.

Furthermore, the cooling effect and the flooding prevention effect can be further enhanced by combining any one or two or more of the following (a) to (f) with the above invention.
(A) By forming at least one region of the inner surface of the cooling flow path into an undulating shape that increases the area in the flow path, the surface area of the cooling flow path effective for water vaporization is increased.
(B) A region separating the cooling channel from the reaction channel and at least one region around the cooling channel are formed of a porous material in which a material having a higher thermal conductivity than the base material of the porous material is dispersed. By doing so, the thermal conductivity of the porous body is increased.
(C) By providing a turbulent flow generating means for generating a turbulent flow of the oxidant gas flow in at least one region of the inner surface of the cooling channel, vaporization of water is promoted.
(D) By forming a region separating the cooling channel from the reaction channel and at least one region around the cooling channel with a porous body in which a fine tube material is dispersed in a base material of the porous body. , Increase the water transfer efficiency.
(E) The movement efficiency of water is increased by forming a cut into the surrounding porous body in at least one region of the inner surface of the cooling flow path.
(F) The movement efficiency of water is increased by arranging the flow path so that the bottom of the cooling flow path and the bottom of the reaction flow path face each other.

By combining the following means (g), the electrode can be humidified and the electrolyte can be kept wet.
(G) Since the reaction channel is connected to the downstream side of the cooling channel, the humidified cooling gas is guided to the vicinity of the electrode as a reaction gas.

  In the fuel cell system of the present invention, the entire periphery of the cooling channel is a porous body, and the area of the inner surface of the cooling channel made of the porous body is large. A large amount and efficient arrival at the surface of the cooling flow path will increase the water vaporization efficiency. For this reason, the amount of water vaporization is large, and accordingly, the heat of vaporization taken away from the surroundings is large. Therefore, the cell can be efficiently cooled. And since the vaporization rate of water is high, the retention of the water in a porous body becomes difficult to occur, and the movement of the generated water into the porous body is promoted. Therefore, excess water from the electrode can be efficiently discharged, and flooding on the downstream side (near the outlet of the reaction flow path) of the gas flow path on the electrode side that generates generated water is prevented.

  Further, the water is vaporized, so that the cooling gas flowing through the cooling channel is sufficiently humidified. The humidified cooling gas is circulated in the reaction channel to humidify the electrode and / or electrolyte, or to the steam reforming reaction or water gas shift reaction reformer as necessary to supply reaction water. By doing so, the produced water can be used effectively.

  Further, by connecting the reaction channel to the downstream side of the cooling channel, the cooling gas humidified in the upstream cooling channel as described above is used as the reaction gas on the downstream side as it is, so that the electrode and the electrolyte can be used. It can also be humidified.

  Accordingly, it is possible to provide a fuel cell system capable of cooling the separator by the heat of vaporization of the generated water accompanying the power generation of the fuel cell and preventing flooding in the reaction channel on the electrode side that generates the generated water. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 4 is an exploded perspective view showing a configuration of a cell of the solid polymer electrolyte fuel cell to which the fuel cell system according to the first embodiment of the present invention is applied.
FIG. 5 is a cross-sectional view in a plane perpendicular to the flow direction of the flow path of the cell to which the fuel cell system according to the first embodiment of the present invention is applied.

As shown in FIGS. 4 and 5, the cell 1 of the solid polymer electrolyte fuel cell of the present embodiment includes a membrane-electrode assembly 2, a fuel electrode side separator 3, a cooling gas channel 9, and a reactive gas channel. 10 is sandwiched between the oxidant electrode-side separator 4 provided with 10.
The membrane-electrode assembly 2 includes a central solid polymer electrolyte membrane, fuel electrodes on both sides thereof, and an oxidizer electrode, although not shown here.

The solid polymer electrolyte membrane functions as an ion conductive electrolyte while isolating the fuel gas and the oxidant gas. For example, a known polymer electrolyte membrane such as a perfluorocarbon sulfonic acid membrane can be applied.
The fuel electrode and the oxidant electrode provided on both sides of the solid polymer electrolyte membrane are a catalyst layer (fuel electrode side catalyst layer, oxidant electrode side catalyst layer) facing each other with the electrolyte membrane sandwiched between the electrolyte membrane and the catalyst layer. It consists of a gas diffusion layer (fuel electrode side gas diffusion layer, oxidant electrode side gas diffusion layer) provided on top. As these catalyst layer and gas diffusion layer, known ones can be applied.

As shown in FIG. 5, the fuel electrode side separator 3 is provided with a groove 7 on a surface facing the membrane-electrode assembly 2, and the fuel is formed between the groove 7 and the surface of the membrane-electrode assembly. A gas flow path 8 is formed. During power generation, a gas containing hydrogen or generating hydrogen is circulated through the fuel gas passage 8.
Further, the fuel electrode side separator 3 prevents gas leakage of the fuel gas, and electrically connects the cells 1 when the cells 1 are stacked to form a fuel cell stack.
Therefore, the fuel electrode side separator 3 is made of a conductive and dense material such as a high-density carbon sheet or metal sheet. As shown in FIG. 5, the oxidant electrode side separator 4 includes a cooling channel 9 and a reaction channel 10, and guides the oxidant gas to the membrane-electrolyte assembly 2 through the reaction channel 10. This prevents gas leakage of the oxidant gas and electrically connects the cells 1 when the cells 1 are stacked to form a fuel cell stack.

  The oxidant electrode side separator 4 is mainly composed of the porous layer 11 mainly composed of the porous bodies 13 and 14 on the side facing the membrane-electrode assembly 2 and the dense material on the opposite side. It consists of a dense layer 12. Furthermore, in this embodiment, the porous layer 11 is provided in contact with the membrane-electrode assembly 2, and the first porous body 13 is a region that separates the cooling flow path 9 and the reaction flow path 10. And a second porous body 14 sandwiched between the first porous body 13 and the dense layer 12.

As the dense material for forming the dense layer 12, a dense material having conductivity such as a high-density carbon sheet or metal sheet is suitable.
The substance forming the first and second porous bodies 13 and 14 is preferably a conductive substance, and is independently porous carbon such as a porous carbon sheet, a porous carbon film, and porous carbon paper. In addition to a porous metal such as a metal mesh or a metal foam, a conductive material dispersed in a non-conductive porous material can also be applied.

The reaction channel 10 has a groove 15 provided in the first porous body 13 on the surface of the oxidant electrode-side separator 4 facing the membrane-electrode assembly 2, and the surface of the membrane-electrode assembly. It is formed with. During power generation, an oxidant gas (a gas containing oxygen or generating oxygen) is caused to flow through the reaction channel 10.
The cooling channel 9 has a groove 16 formed on the surface of the first porous body 13 in contact with the second porous body 14 and a second porous body so that the groove 16 is aligned with the groove 16 when combined. The grooves 17 are formed on the surface of the material 14. Therefore, the cooling flow path 9 of the present embodiment is formed by the porous bodies 13 and 14 all around it. Moreover, the cooling flow path 9 is formed in the separator 4 on the side of the generated water generation of the single fuel cell as in this embodiment, and the generated water is effectively used to cool the fuel cell. This is preferable.

The cooling flow path 9 extends along the surface direction of the separator 4 at a depth relatively closer to the adjacent cell than the depth (the distance in the thickness direction of the separator 4) where the reaction flow path 10 is provided. It is provided as follows. In addition, the reaction channel 10 extends along the surface direction of the separator 4 at a depth relatively closer to the electrode than the depth at which the cooling channel 9 is provided (the thickness direction of the separator 4). Is provided.
That is, in the present embodiment, “the cooling flow path 9 is provided at a depth closer to the adjacent cell in the separator 4” and “the reaction flow path 10 is provided at a depth closer to the electrode in the separator 4”. Is the relative positional relationship between the cooling flow path 9 and the reaction flow path 10, “in the separator 4, the cooling flow path 9 is formed at a position closer to the adjacent cell than the reaction flow path 10. It means that the channel 8 is formed at a position closer to the electrode than the cooling channel 9 ”.

  The porous layer 11 may be formed from a single porous body, and the cooling flow path 9 may be formed as a through hole in the layer. However, the cooling flow path 9 is the first as in this embodiment. It is preferable that the grooves 16 and 17 formed on the surfaces of the porous body 13 and the second porous body 14 are aligned so that the cooling channel 9 can be easily formed.

  As the cooling gas flowing through the cooling flow path 9, a gas having a lower humidity than the reaction gas flowing through the reaction flow path 10 is used. In the present invention, by using a gas having a humidity lower than that of the reaction gas as the cooling gas, moisture is preferentially vaporized into the cooling flow path 9 to obtain a high cooling effect. Furthermore, in the present invention, since the entire periphery of the cooling flow path 9 is the porous bodies 13 and 14, the generated water can be vaporized from all the surfaces of the cooling flow path 9, and the water vaporization efficiency is increased. High effect. In particular, the depth at which the reaction flow path 10 in the separator 4 is provided is close to the oxidant electrode, the position close to the membrane-electrolyte assembly 2, and the depth at which the cooling flow path 9 is provided in the separator 4 is set to this cell. It is preferable from the viewpoint of obtaining a sufficient cooling effect by moving the moisture in the porous body for a long distance, so that it is closer to the adjacent cell stacked in 1 than the reaction channel 10 from the membrane-electrode assembly 2. .

  When the cooling channel 9 is provided on the cathode side of the solid polymer electrolyte fuel cell as in the present embodiment, the cooling gas is an oxidant gas (a gas containing oxygen or generating oxygen). Is preferable, and air is more preferable. In particular, since air introduced from the outside environment, that is, air taken in directly from the natural environment is usually at a lower temperature than the cell 1 during power generation, heat exchange with the porous bodies 13 and 14 forming the cooling flow path 9 is performed. Therefore, the porous bodies 13 and 14 are cooled, and the entire cell 1 is further cooled. Conversely, when the cooling channel is provided on the anode side, it is preferable that the gas contains hydrogen or generates hydrogen. If the same kind of gas is used for the cooling gas that flows through the cooling flow path 9 and the reaction gas that flows through the reaction flow path 10 adjacent to the cooling flow path 9 in this way, the cooling gas passes through the porous bodies 13 and 14. Even if the reaction gas and the reaction gas are circulated, there is no interaction between them, such as a chemical reaction.

  The cooling gas is humidified by vaporization of moisture into the cooling channel while flowing through the cooling channel 9. This humidified cooling gas is preferably used for power generation of the fuel cell itself. For example, when the fuel cell system according to the present invention is applied to the cathode side as in the present embodiment and the cooling gas is a gas containing oxygen or generating oxygen, the cooling flowed through the cooling flow path 9 and humidified The gas is sent to a reformer for a steam reforming reaction or a water gas shift reaction or the like to make a steam-containing reaction gas, or as described in the next second embodiment, the cooling channel is formed at the downstream end of the reaction channel. It can be used for power generation of the fuel cell by supplying it to the reaction flow path as humidified oxidant gas by being connected to the upstream end via the connection portion, or to supply moisture to the reformer, or A special apparatus for humidifying the oxidant gas supplied to the reaction channel can be reduced in size or omitted, which is preferable. In particular, it is preferable that the cooling gas is led to the reaction channel and used as a humidified reaction gas as it is.

  When the cooling gas is air introduced from the outside as in the present embodiment, water is generated with power generation on the oxidant electrode side of the membrane-electrode assembly 2. The generated water reaches the porous layer 11 of the oxidant electrode side separator 4, and most of the generated water passes through the pores of the porous layer 11 and reaches the cooling channel 9. A part of the liquid water that has reached the cooling channel 9 remains in a liquid state and is discharged to the outside by riding on the air flow that flows through the cooling channel 9. It evaporates and is discharged to the outside of the cell 1 together with the air. As the water evaporates, the heat of vaporization is taken away from the surroundings, so that the cooling efficiency in the region of the cooling flow path 9 is improved.

  In the cooling channel 9, water vaporizes from the surface of the porous bodies 13 and 14 into the channel, so that the larger the surface area occupied by the porous bodies 13 and 14 on the cooling channel surface, the more water is vaporized. . In the fuel cell system of the present embodiment, since the entire periphery of the cooling flow path 9 is formed by the porous bodies 13 and 14, when a part of the cooling flow path 9 is formed of a dense material (for example, FIG. 5, the surface area occupied by the porous bodies 13 and 14 on the surface of the cooling flow path is larger than the case where the portion of the porous body 14 forming the adjacent cell side of the cooling flow path 9 is formed of the dense material 12. .

  Therefore, in the fuel cell system of the present embodiment, the amount of water vaporized in the cooling channel 9 increases, and the vaporization heat taken away from the surroundings increases accordingly. Therefore, the cell 1 can be efficiently cooled as compared with the case where air is simply circulated and cooled.

  In addition, when a part of the cooling flow path is not made of a porous material but is made of a dense material, the portion formed of the dense material prevents water from passing through the dense material. Even in the vicinity of the formed region, even if it is formed of a porous body, water is likely to stay, and it is difficult to work effectively as a water movement path. For this reason, the effective movement path of water is limited to a space away from the dense material, and the efficient movement of water is restricted, and the water is not efficiently vaporized.

  However, in the case of the fuel cell system according to the present embodiment, since the porous body is interposed between the dense layer 12 that prevents gas leakage to the adjacent cells and the cooling flow path 9, the dense layer 12 and the cooling flow Water can also circulate between the road 9. For this reason, almost all the spaces in the porous layer 11 become effective movement paths of water. Therefore, the water that permeates from the oxidant electrode side of the membrane-electrode assembly 2 efficiently reaches the surface of the cooling flow path 9, thereby increasing the water vaporization efficiency. Therefore, high cooling efficiency can be realized in the fuel cell system of the present embodiment.

  And since the vaporization efficiency in the cooling flow path 9 is good and the effective movement route of the water in the porous layer 11 is increasing, the retention of the water in the porous layer 11 is less likely to occur. Water becomes easy to enter the porous layer 11. Therefore, the removal of water from the oxidizer electrode becomes efficient, and the occurrence of flooding near the outlet of the reaction channel 10 is prevented.

(First modification)
FIG. 6 shows a first modification of the first embodiment.
In the solid polymer electrolyte fuel cell of the first modified example, the cross-sectional shape of the cooling channel 9 and the reaction channel 10 in the plane perpendicular to the air flow direction and the arrangement of the reaction channel 10 are the first embodiment. Unlike the fuel cell, the cross-sectional shape of the cooling channel 9 is elliptical, the cross-sectional shape of the reaction channel 10 is circular, and the entire periphery of the reaction channel 10 is formed of a porous body.
As in this modification, in the solid polymer electrolyte fuel cell according to the present invention, there is no particular limitation on the cross-sectional shape of the cooling channel 9 and the reaction channel 10 in the plane perpendicular to the air flow direction.
Moreover, the reaction flow path 10 is good also as the arrangement | positioning buried in the porous bodies 13 and 14 like this modification.

(Second Embodiment)
FIG. 7 is an exploded perspective view showing a configuration of a cell of a solid polymer electrolyte fuel cell to which a fuel cell system according to a second embodiment of the present invention is applied.
FIG. 8 is a cross-sectional view in a plane perpendicular to the flow direction of the flow path of the cell to which the fuel cell system according to the second embodiment of the present invention is applied.
The fuel cell system of the second embodiment is a preferred form of the first embodiment, and in the fuel cell system, the cooling flow path is connected at its downstream end to the upstream end of the reaction flow path via a connection portion. Is. Accordingly, there are many similarities to the fuel cell of the first embodiment, and only the differences will be described below. 7 and 8, the same components as those of the fuel cell of the first embodiment are denoted by the same reference numerals.

As shown in FIG. 7, in the oxidant electrode side separator 4 of the second embodiment, the downstream side cooling channel 9 is connected to the downstream portion via a connecting portion (usually provided at the peripheral edge of the separator). An oxidant gas channel 6 connected to the reaction channel 10 is provided.
The cooling flow path 9 extends along the surface direction of the separator 4 at a depth relatively closer to the adjacent cell than the depth at which the reaction flow path 10 is provided (distance in the thickness direction of the separator 4). And is connected to the connecting portion at the downstream end thereof. The connecting portion proceeds vertically in the separator 4 toward the membrane-electrode assembly 2 and ends at a depth relatively close to the electrode, where it connects with the upstream end of the reaction channel 10. The reaction channel 10 extends in the surface direction of the separator 4 at a depth connected to the connection portion. Accordingly, as the oxidant gas flow path 6 as a whole including the cooling flow path 9, the connection portion, and the reaction flow path 10, the upstream flow path 9 extends in the horizontal direction in the separator 4 and is folded in the vertical direction at the connection portion. Thus, the downstream flow path 10 has a depth different from the depth of the upstream flow path 9 and a flow path pattern extending in the horizontal direction in the separator 4 again.

  In this way, the depth at which the reaction channel 10 in the separator 4 is provided is close to the oxidizer electrode, the position near the membrane-electrolyte assembly 2, and the depth at which the cooling channel 9 is provided in the separator 4 is The reason why the position closer to the adjacent cell stacked on the cell 1 is farther from the membrane-electrode assembly 2 than the reaction channel 10 is to move the moisture within the porous body for a long distance to obtain a sufficient cooling effect. It is. In addition, the oxidant gas supplied from the outside is first circulated through the cooling flow path 9 to be heated and humidified, and then is flowed to the reaction flow path 10 adjacent to the oxidant electrode, whereby the oxidant electrode is subjected to electrochemistry. It is also to promote the reaction.

  The oxidant gas that flows through the oxidant gas channel 6 functions as a cooling gas in the region of the cooling channel 9 and functions as a reaction gas that supplies oxygen to the oxidant electrode in the region of the reaction channel 10. Since the oxidant gas humidified by flowing through the cooling channel 9 flows into the reaction channel 10 and supplies moisture to the oxidant electrode on the upstream side of the reaction channel that tends to dry, the local area of the solid polymer electrolyte membrane Dryness can be prevented. Further, since the oxidant gas warmed when flowing through the cooling flow path 9 is used as the reaction gas, the electrode reaction is promoted. Thus, according to the fuel cell humidification system of the present embodiment, in addition to being able to cool the fuel cell using the generated water, the generated water generated by the electrochemical reaction and the extra humidified water are used to generate the generated water. It is possible to humidify the reaction gas in the upstream region on the electrode side where the generation occurs, and to keep the solid polymer electrolyte membrane moist. Therefore, a special device for humidifying the oxidant gas supplied to the reaction channel can be reduced in size or omitted.

(Second modification)
FIG. 9 shows a second modification of the second embodiment. The constituent elements are the same as those in the second embodiment, and are therefore denoted by the same reference numerals.
In the solid polymer electrolyte fuel cell of the second modification to which the fuel cell system according to the present invention is applied, the arrangement of the cooling channel 9 with respect to the reaction channel 10 is different from that of the fuel cell system of the first embodiment. First, in the surface direction of the oxidant electrode side separator 4 (the direction horizontal to the membrane-electrode assembly 2), the cooling channel 9 is regularly arranged between the plurality of reaction channels 10. Further, in the thickness direction of the oxidant electrode side separator 4 (direction perpendicular to the membrane-electrode assembly 2), the portion 9a of the cooling channel 9 closest to the membrane-electrode assembly 2 (the bottom of the cooling channel 9) is The membrane-electrode assembly 2 is closer than the portion 10a of the reaction channel 10 closest to the adjacent cell (the bottom of the reaction channel 10).

In the second modification, both of the relationships shown in the following (1) and (2) are established.
(1) The portion 9a closest to the membrane-electrode assembly 2 in the cooling channel 9 is closer to the adjacent cell than the portion 10b closest to the membrane-electrode assembly 2 in the reaction channel 10.
(2) The portion 9b closest to the adjacent cell of the cooling channel 9 is closer to the adjacent cell than the portion 10a closest to the adjacent cell of the reaction channel 10.

  If both the flow paths 9 and 10 are arranged while keeping the positional relationship of (1) and (2) above, first, when the air from the outside that has been dried first flows into the cooling flow path 9, the porous body It is humidified with the generated water that has been discharged through 13 and 14 and has been discharged. Next, the humidified air flows into the reaction channel 10 near the electrode, and humidifies the solid polymer electrolyte membrane. If this positional relationship is reversed, the dried air flowing in the cooling flow path 9 may directly take water from the membrane-electrode assembly 2 on the upstream side of the reaction flow path 10.

  As in this modification, in the fuel cell system in which the cooling channel is connected to the upstream end of the reaction channel via the connecting portion at the downstream end thereof, in the positional relationship in the vertical direction of the membrane-electrode assembly 2, It is preferable that both the relationships shown in the above (1) and (2) are satisfied.

(Third embodiment)
FIG. 10 is a cross-sectional view in a plane perpendicular to the flow direction of the cell flow path of the solid polymer electrolyte fuel cell to which the fuel cell system according to the third embodiment of the present invention is applied.
In the fuel cell system of the third embodiment, the shape of the cooling channel is only different from that of the first embodiment, so only that will be described, and the same components are assigned the same reference numerals.

  The cross section of the cooling channel 19 shown in FIG. 10 in a plane perpendicular to the air flow direction has a thin rectangular uneven shape 18 in the region facing the membrane-electrode assembly 2, and the channel inner area. Is increasing. The uneven shape 18 extends in the air flow direction of the cooling flow path 19 and forms a narrow groove.

  When the vaporization rate per unit area is constant, the amount of vaporization per unit time increases as the surface area of the water increases. In the cooling channel 19, since water is vaporized from the surfaces of the porous bodies 13 and 14, the amount of water vaporized increases as the surface area of the porous bodies 13 and 14 increases. As described above, in the cooling flow path 19 of the second embodiment, the area in the flow path is increased due to the undulating shape composed of the concavo-convex shape 18, and the porous body 13 is larger than the cooling flow path having a rectangular cross section. , 14 has a large surface area, and the amount of water vaporized therefrom is large. As described above, in the cooling channel 19 according to the present embodiment, by forming at least one region of the inner surface of the cooling channel in an undulating shape, the amount of water vaporization increases as compared with the rectangular cooling channel, and accordingly, The heat of vaporization is also great. Therefore, the cell 1 can be efficiently cooled.

Since the amount of water vaporized in the cooling flow path 19 is larger, the water stays in the porous layer 11 less easily, and the water generated in the membrane-electrode assembly 2 penetrates into the porous layer 11. It becomes easy. Therefore, the removal of water from the oxidant electrode becomes more efficient, and the occurrence of flooding on the downstream side of the reaction gas channel 10 can be prevented.
As a result, the air flowing through the cooling channel 19 is humidified more efficiently. This humidified cooling gas such as air can also be used effectively for power generation of the fuel cell.

(Third Modification)
FIG. 11 shows a fuel cell system according to a modification of the third embodiment, which differs from the third embodiment only in the cross-sectional shape of the cooling flow path 20. And in FIG. 11, the same code | symbol was attached | subjected to the same thing as the component of 3rd Embodiment.
Also in this modification, the region facing the membrane-electrode assembly 2 in the cross section in the plane perpendicular to the air flow direction of the cooling flow path 20 has the uneven shape 21, but the uneven shape 21 is a sine curve. Such a smooth curved shape.
Thus, the undulating shape that increases the area in the flow path may be a curved surface shape.

  Furthermore, the shape of the cooling channel is not limited to that shown in the third embodiment and the third modification, and for example, a cross section perpendicular to the air flow direction may be a circle having an uneven shape. Further, in the third embodiment and the third modification, the concave and convex shapes 18 and 21 of the cross sections of the cooling channels 19 and 20 are provided only in the portion facing the membrane-electrode assembly 2, but in other directions. It may be provided. And the undulation shape does not necessarily need to be provided in the whole along the flow direction of the cooling flow paths 19 and 20, and may be provided only in the part.

(Fourth embodiment)
FIG. 12 is a cross-sectional view in a plane perpendicular to the flow direction of the cell flow path of the solid polymer electrolyte fuel cell to which the fuel cell system according to the fourth embodiment of the present invention is applied. In FIG. 12, the same components as those in the first embodiment are denoted by the same reference numerals.

  The fuel cell system of the fourth embodiment is different from that of the first embodiment in that the porous body forming the oxidant-side separator is different from that of the first embodiment, and at least the region that separates the cooling channel from the reaction channel and the periphery of the cooling channel. One region is formed by a porous body in which a material having a higher thermal conductivity than the base material is dispersed in the base material of the porous body. In addition, there is no restriction | limiting in particular in the shape of the cooling flow path 9, A rectangular shape, circular shape, and all other shapes are applicable.

And the porous bodies 22 and 23 of 4th Embodiment are the metal powder 25 whose base material is porous carbon and whose material whose thermal conductivity is larger than this base material disperse | distributed inside. is there.
The base material is not limited to porous carbon, and may be, for example, a porous metal such as a metal mesh or a metal foam. A material having a higher thermal conductivity than the dispersed base material is a metal, as in this embodiment. In the case of a conductive material such as, a non-conductive porous body may be used.

  The material having a higher thermal conductivity than the dispersed base material is not limited to metal, and is not particularly limited. In the case of using a metal material, those having excellent corrosion resistance are preferred, and for example, those having high corrosion resistance such as titanium and stainless steel are suitable.

  And in this embodiment, although the shape of the material 25 to disperse is a powder form, it may be a strip or a rod, and the size is not particularly limited as long as it fits in the porous layer 24. From the viewpoint of dispersibility, the size is preferably about 0.01 mm to 1 mm.

  The material dispersed in the base material used particularly preferably is a metal powder, a metal piece, or a metal bar. This is because the metal generally has high conductivity, and when these are dispersed in the porous bodies 22 and 23, the function of the separator as a current collector is enhanced.

  In the present embodiment, the metal powder 25 is dispersed substantially uniformly throughout the porous bodies 22 and 23, but may be dispersed only in a part of the region. However, the separator 4 is preferably dispersed with a certain width in the thickness direction.

As described above, the material having high thermal conductivity such as the metal powder 25 is dispersed, so that the thermal conductivity of the porous bodies 22 and 23 is increased, and the metal powder passes through the porous bodies 22 and 23. The heat transfer coefficient between the surface of the cooling flow path composed of water or the porous bodies 22 and 23 and the water reaching the water is increased. Therefore, the supply efficiency of the heat of vaporization to liquid water increases, and the vaporization efficiency of water increases.
As described above, in the fuel cell system according to the present embodiment, since the water vaporization efficiency is high, the heat of vaporization taken from the surroundings also increases. Therefore, the fuel cell system of this embodiment is excellent in cooling efficiency.

And since the vaporization efficiency in the cooling flow path is good, the retention of water in the porous layer 24 is less likely to occur, and the movement of the water generated in the membrane-electrode assembly 2 into the porous layer 24 is promoted, Water is efficiently removed from the oxidizer electrode, and flooding is effectively prevented.
Moreover, since the amount of water vaporization is large, the air flowing through the cooling flow path 9 is efficiently humidified. The humidified air, for example, is then introduced into the reaction channel 10 to supply moisture to the oxidant electrode side located upstream thereof, and used to prevent local drying of the solid polymer electrolyte membrane. In addition, it can be used effectively by, for example, being used to supply reaction water for the reforming reaction by being introduced into the reformer.

(Fifth embodiment)
FIG. 13 is a cross-sectional view taken along a flow direction of a cell flow path of a solid polymer electrolyte fuel cell to which a fuel cell system according to a fifth embodiment of the present invention is applied.
The fuel cell system of the fifth embodiment differs from that of the first embodiment in the shape of the cooling flow path, and generates turbulent flow that generates turbulent flow of oxidant gas flow in at least one region of the inner surface of the cooling flow path 26. Means (for example, rectangular unevenness 27 and the like) are provided. Only differences from the first embodiment will be described below. In FIG. 13, the same components as those of the first embodiment are denoted by the same reference numerals.

The cross section of the cooling channel 26 shown in FIG. 13 on the surface along the air flow direction is provided intermittently from the upstream side to the downstream side of the channel 26 on the surface side facing the membrane-electrode assembly 2. A rectangular unevenness 27 is provided. Since the rectangular irregularities 27 serving as the turbulent flow generating means are formed on the inner surface of the cooling flow path 26, the boundary layer of the air flow on the inner surface of the cooling flow path is disturbed, and turbulence is generated. This turbulent flow increases the efficiency of water vaporization from the cooling channel surface.
Thus, in the fuel cell system according to the present embodiment, since the water vaporization efficiency is high, the amount of water vaporization increases, and the increase in water vaporization efficiency increases the heat of vaporization taken from the surroundings. Therefore, the fuel cell system of this embodiment is excellent in cooling efficiency.

And since the vaporization efficiency in the cooling flow path 26 is high, the retention of water in the porous layer 11 hardly occurs, and the movement of the water generated in the membrane-electrode assembly 2 into the porous layer 11 is promoted. Water is efficiently removed from the oxidizer electrode, and flooding is prevented from occurring.
As a result, the air flowing through the cooling flow path 26 is efficiently humidified. This humidified air can be effectively used for power generation of the fuel cell.

  In this embodiment, the means for generating the turbulent flow is the rectangular unevenness 27 provided intermittently from the upstream to the downstream of the flow path, but intermittent undulations other than the rectangle are provided from the upstream to the downstream of the flow path. In addition, any other means may be used as long as it can disturb the boundary layer of the air flow on the inner surface of the cooling flow path and change the flow from laminar flow to turbulent flow. For example, the cooling channel is provided with an inner surface having a surface roughness composed of irregularities with a height of about 0.1 mm, the traveling direction of the cooling channel is bent many times at an angle, or in the cooling channel It is also possible to arrange an obstacle that obstructs the air flow. In particular, since the processing is easy, the surface roughness can be reduced by forming an uneven shape along the flow direction in the cooling channel or by providing a fine uneven shape such as a dimple shape on the inner surface of the cooling channel. It is preferable to increase the size and cause turbulence in the air flow.

(Sixth embodiment)
FIG. 14 is a cross-sectional view taken along a plane perpendicular to the flow direction of the cell flow path of the solid polymer electrolyte fuel cell to which the fuel cell system according to the sixth embodiment of the present invention is applied.
In the fuel cell system of the sixth embodiment, the porous layer forming the oxidant side separator is different from that of the first embodiment. At least one region is formed by a porous body in which the fine tube material 31 is dispersed in the base material of the porous body. Only differences from the first embodiment will be described below. In FIG. 14, the same components as those in the first embodiment are denoted by the same reference numerals. In addition, there is no restriction | limiting in particular in the shape of a cooling flow path, A rectangular shape, circular shape, and all other shapes are applicable.

The porous layer 28 of the sixth embodiment is made up of porous bodies 29 and 30 containing a tube material 31 inside.
The material of the tube material 31 is not particularly limited, and any material such as glass, resin, metal, or fiber can be applied. However, those having excellent corrosion resistance are preferable, and for example, those having high corrosion resistance such as glass, resin, titanium, and stainless steel are preferable.

  The length of the tube material 31 may be in a range that can be accommodated in the porous layer 28. However, all the tubular materials 31 contained in the porous layer 28 should not be substantially parallel to the membrane-electrode assembly 2. Therefore, the length of the tube material 31 is preferably in the range of 0.05 to 0.3 mm, more preferably 0.1 to 0.2 mm. Further, the thickness of the tube material 31 is not particularly limited, but is preferably 0.3 mm or less. And the shape of the hole which the tube material 31 has, and a diameter are not restrict | limited in particular. And the outer diameter of the tube material 31 is also arbitrary. Since the holes of the tube material 31 serve as an effective movement path of water, a part of the water generated at the oxidant electrode of the membrane-electrode assembly 2 passes through the porous layer 28 in the hole of the tube material 31. By moving through, the cooling flow path 9 is reached more quickly. Therefore, water can be effectively discharged from the oxidizer electrode. Accordingly, water is efficiently removed from the oxidizer electrode, and flooding is prevented from occurring.

  In addition, since a large amount of water is allowed to reach the cooling flow path 9 per unit time, the amount of water vaporization in the cooling flow path 9 increases, and the vaporization heat taken away from the surroundings increases accordingly. Therefore, the humidification system of the fuel cell of this embodiment is excellent in cooling efficiency.

  Moreover, in the fuel cell system of this embodiment, the water produced | generated by electrode reaction vaporizes in the air which flows through the cooling flow path 9 as mentioned above, and the air is humidified. The humidified air, for example, is then introduced into the reaction channel 10 to supply moisture to the oxidant electrode side located upstream thereof, and used to prevent local drying of the solid polymer electrolyte membrane. In addition, it can be used to supply reaction water for the reforming reaction by introducing it into the reformer.

(Seventh embodiment)
FIG. 15 is a cross-sectional view in a plane perpendicular to the flow direction of the cell flow path of the solid polymer electrolyte fuel cell to which the fuel cell system according to the seventh embodiment of the present invention is applied.
The fuel cell system of the seventh embodiment differs from that of the first embodiment in the shape of the cooling channel, and forms a notch 33 that enters the surrounding porous body in at least one region of the inner surface of the cooling channel 32. . Only differences from the first embodiment will be described below. In FIG. 15, the same components as those in the first embodiment are denoted by the same reference numerals.

The cooling channel 32 of the present embodiment has a plurality of cuts 33 extending toward the membrane-electrode assembly 2 in a region of the inner surface. The cut 33 does not extend in the air flow direction of the cooling flow path 32 but is a hole formed in a linear shape.
The length, the hole shape, the diameter, and the number of the cuts 33 are not particularly limited. Moreover, there is no restriction | limiting in particular about the direction provided, However, It is preferable to provide toward the membrane-electrode assembly 2 like this embodiment.

These notches 33 provide an effective movement path for water. A part of the water generated at the oxidant electrode of the membrane-electrode assembly 2 moves through the cut 33 in the porous layer 11, thereby reaching the cooling flow path 32 more quickly. Therefore, water is effectively discharged from the oxidizer electrode, and flooding is prevented from occurring.
Further, since a large amount of water reaches the cooling flow path 32 per unit time, the amount of water vaporization in the cooling flow path 32 increases, and accordingly, the heat of vaporization taken from the surroundings also increases. Therefore, the fuel cell system of this embodiment is excellent in cooling efficiency.

  The air flowing through the cooling channel 32 is humidified more effectively. The humidified air, for example, is then introduced into the reaction channel 10 to supply moisture to the oxidant electrode side located upstream thereof, and used to prevent local drying of the solid polymer electrolyte membrane. In addition, it can be used to supply reaction water for the reforming reaction by introducing it into the reformer.

(Eighth embodiment)
FIG. 16 is a cross-sectional view in a plane perpendicular to the flow direction of the cell flow path of the solid polymer electrolyte fuel cell to which the fuel cell system according to the eighth embodiment of the present invention is applied.
The fuel cell system of the eighth embodiment is different from that of the first embodiment in the shape of the cooling channel and the position where the cooling channel is provided, and the bottom 9a of the cooling channel 9 and the bottom 10a of the reaction channel 10 face the front. The flow path is arranged as follows. In FIG. 16, the same components as those in the first embodiment are denoted by the same reference numerals.

The cooling channel 9 in this embodiment has a rectangular cross-sectional shape perpendicular to the air flow, and the width of the bottom 9a is substantially the same as the width of the bottom 10a of the reaction channel 10. . Furthermore, the bottom 9a of the cooling channel is provided in parallel with the bottom 10a of the reaction channel.
Thus, since the flow paths 9 and 10 are arranged so that the bottom 9a of the cooling flow path and the bottom 10a of the reaction flow path face each other, the distance between both flow paths is shortened, and the reaction flow path 10 The movement distance of water from the cooling channel 9 to the cooling channel 9 is shortened. Therefore, the water generated at the oxidant electrode of the membrane-electrode assembly 2 reaches the cooling channel 9 more quickly. Therefore, water is effectively discharged from the oxidizer electrode, and flooding is prevented from occurring.

  When the width of the bottom 9a of the cooling channel is different from the width of the bottom 10a of the reaction channel, the midpoint of dividing the width of the bottom 9a into two in the cross section of the cooling channel and the cross section of the reaction channel In FIG. 5, the flow paths 9 and 10 are arranged so that the midpoint that bisects the width of the bottom 10 a faces the front.

In addition, since a large amount of water is allowed to reach the cooling flow path 9 per unit time, the amount of water vaporization in the cooling flow path 9 increases, and the vaporization heat taken away from the surroundings increases accordingly. Therefore, the fuel cell system of this embodiment is excellent in cooling efficiency.
Further, the water generated in the membrane-electrode assembly 2 is more efficiently removed, and flooding downstream of the reaction gas channel 10 (near the outlet of the reaction channel) is prevented.
The air flowing through the cooling channel 9 is efficiently humidified. The humidified air is then introduced into the reaction channel 10 to supply moisture to the oxidant electrode side located upstream thereof, and used to prevent local drying of the solid polymer electrolyte membrane. In addition, it can be used to supply reaction water for the reforming reaction by introducing it into the reformer.

  In all the embodiments described above, the application of the fuel cell system according to the present invention to a solid polymer electrolyte fuel cell has been shown. However, other types of fuel cells, such as phosphoric acid fuel cells, molten carbon dioxide, The present invention can also be applied to a salt fuel cell, a solid oxide fuel cell, and the like. In particular, it is preferable to apply the present invention to the reaction gas channel on the side of discharging the generated water. Moreover, although the example which combined the 2nd-8th embodiment with 1st Embodiment was shown in the above description, two or more forms of 2nd-8th embodiment were shown to 1st Embodiment. The effects of the present invention can be further improved by combining features.

  As described above, according to the fuel cell system of the present invention, the entire periphery of the cooling flow path is a porous body, the surface area made of the porous body is large, and almost all of the porous body. Since the space is an effective movement path of water, a large amount of water from the oxidant electrode side of the membrane-electrode assembly reaches the surface of the cooling channel, and efficiently reaches the surface. Water vaporization efficiency increases. For this reason, the amount of water vaporized in the cooling channel increases, and the heat of vaporization taken away from the surroundings increases accordingly. Therefore, the cell can be efficiently cooled.

And it becomes difficult for the stagnation of water in the porous body to occur, and the penetration of the generated water into the porous body is promoted. Therefore, the removal of water from the oxidant electrode becomes efficient, and the occurrence of flooding on the downstream side of the oxidant gas channel (near the outlet of the reaction channel) is prevented.
As a result, the air flowing through the cooling channel can be sufficiently humidified, and can be used as it is as a reaction gas to keep the solid polymer electrolyte membrane moist, or as a reformer for a steam reforming reaction or a water gas shift reaction. Water vapor can also be supplied.

The graph which shows the relationship between the surface area of a cooling flow path, and the evaporation amount of the produced water to the air which flows through the cooling flow path. The graph which shows the relationship between a cooling channel cross-sectional area and the evaporation amount of the produced water to the air which flows through the cooling channel. The graph which shows the relationship between the density of the porous body which forms a cooling flow path, and the evaporation amount of the produced water to the air which flows through the cooling flow path. 1 is an exploded perspective view showing a configuration of a cell of a solid polymer electrolyte fuel cell to which a fuel cell system according to a first embodiment of the present invention is applied. 1 is a cross-sectional view in a plane perpendicular to a flow direction of a cell flow path of a solid polymer electrolyte fuel cell to which a fuel cell system according to a first embodiment of the present invention is applied. Sectional drawing in a surface perpendicular | vertical to the flow direction of the flow path of the cell of the polymer electrolyte fuel cell to which the fuel cell system which concerns on the 1st modification of 1st Embodiment is applied. The disassembled perspective view which shows the structure of the cell of the solid polymer electrolyte fuel cell to which the fuel cell system which concerns on 2nd Embodiment of this invention is applied. Sectional drawing in the surface perpendicular | vertical to the flow direction of the flow path of the cell of the polymer electrolyte fuel cell to which the fuel cell system which concerns on 2nd Embodiment of this invention is applied. Sectional drawing in a surface perpendicular | vertical to the flow direction of the flow path of the cell of the polymer electrolyte fuel cell to which the fuel cell system which concerns on the 2nd modification of 2nd Embodiment is applied. Sectional drawing in the surface perpendicular | vertical to the flow direction of the flow path of the cell of the polymer electrolyte fuel cell to which the fuel cell system which concerns on 3rd Embodiment of this invention is applied. Sectional drawing in the surface perpendicular | vertical to the flow direction of the flow path of the cell of the polymer electrolyte fuel cell to which the fuel cell system which concerns on the 3rd modification of 3rd Embodiment is applied. Sectional drawing in the surface perpendicular | vertical to the flow direction of the flow path of the cell of the polymer electrolyte fuel cell to which the fuel cell system which concerns on 4th Embodiment of this invention is applied. Sectional drawing in the surface along the flow direction of the flow path of the cell of the polymer electrolyte fuel cell to which the fuel cell system which concerns on 5th Embodiment of this invention is applied. Sectional drawing in a surface perpendicular | vertical to the flow direction of the flow path of the cell of the polymer electrolyte fuel cell to which the fuel cell system which concerns on 6th Embodiment of this invention is applied. Sectional drawing in a surface perpendicular | vertical to the flow direction of the flow path of the cell of the polymer electrolyte fuel cell to which the fuel cell system which concerns on 7th Embodiment of this invention is applied. Sectional drawing in a surface perpendicular | vertical to the flow direction of the flow path of the cell of the polymer electrolyte fuel cell to which the fuel cell system which concerns on 8th Embodiment of this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cell 2 ... Membrane-electrode assembly 3 ... Fuel electrode side separator 4 ... Oxidant electrode side separator 6 ... Oxidant gas channel 7 ... Groove 8 ... Fuel gas channel 9 ... Cooling channel 9a ... Cooling channel Bottom portion 9b: Portion of cooling channel closest to adjacent cell 10: Reaction channel 10a: Bottom portion of reaction channel 10b: Portion of reaction channel closest to adjacent cell 11 ... Porous layer 12 ... Dense layer 13: First Porous body 14 ... second porous body 15 ... groove 16 ... groove 17 ... groove 18 ... uneven shape 19 ... cooling channel 20 ... cooling channel 21 ... uneven shape 22 ... first porous body 23 ... first 2 porous body 24 ... porous layer 25 ... metal powder 26 ... cooling flow path 27 ... rectangular unevenness 28 ... porous layer 29 ... first porous body 30 ... second porous body 31 ... tube material 32 ... Cooling channel 33 ... Incision

Claims (8)

A fuel cell system comprising at least one cell having electrodes disposed on both sides of an electrolyte, and a separator disposed further outside the electrode,
A part of the separator is formed of a porous body, and is disposed on the surface of the porous body that is in contact with the electrode of the porous body, and supplies a reaction gas to the electrode, and the interior of the porous body And a cooling channel that circulates a cooling gas having a humidity lower than that of the reaction gas flowing through the reaction channel.   2. The fuel cell system according to claim 1, wherein at least one region of the inner surface of the cooling flow path is formed in an undulating shape that increases an area in the flow path.   The region separating the cooling channel from the reaction channel and at least one region around the cooling channel are formed of a porous material in which a material having a higher thermal conductivity than the base material of the porous material is dispersed. Item 3. The fuel cell system according to Item 1 or 2.   4. The fuel cell system according to claim 1, wherein turbulent flow generating means for generating turbulent flow of an oxidant gas flow is provided in at least one region of the inner surface of the cooling flow path.   The region separating the cooling channel from the reaction channel and at least one region around the cooling channel are formed of a porous body in which a fine tube material is dispersed in a base material of the porous body. 5. The fuel cell system according to any one of 4.   The fuel cell system according to any one of claims 1 to 5, wherein a cut is formed in at least one region of the inner surface of the cooling channel to enter a surrounding porous body.   The fuel cell system according to any one of claims 1 to 5, wherein the flow path is disposed so that a bottom of the cooling flow path and a bottom of the reaction flow path face each other. The fuel cell system according to claim 1, wherein the reaction channel is connected to a downstream side of the cooling channel.

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