JPH07105960A - Fuel cell - Google Patents

Abstract

PURPOSE:To provide a fuel cell which can enhance the power generating effi ciency as a whole by lessening the pressure loss at each cooling plate, and reducing the power of an auxiliary unit required when air is to be pressure fed to the cooling plates. CONSTITUTION:A fuel cell concerned is so structured that a cell element 8, where an anode 6 and a cathode 7 are arranged with an electrolyte 5 interposed, and separators 11, 12, 15 are laminated and that a cooling plate 1 equipped with a plurality of cooling air passages 3 partitioned by ribs 2 is inserted per certain number of cell elements 8. In the middle stream of each air passage 3 in the cooling plate 1, heat conducting members 4 less tall than the ribs 2 are furnished in parallel with the ribs 2, and the abovementioned anode 6 and cathode 7 are located on the oversurface and undersurface of the laminate mating with this middle stream of air passage 3 where the heat conducting members 4 are extending.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an air-cooled fuel cell,
Specifically, it relates to improvement of the cooling plate.

[0002]

2. Description of the Related Art A fuel cell is a device for directly converting chemical energy of supplied gas into electric energy.
Currently, phosphoric acid fuel cells, molten carbonate fuel cells,
Research on solid oxide fuel cells etc. is actively conducted,
High power generation efficiency is expected. FIG. 5 is a cross-sectional perspective view of a conventional air-cooled fuel cell, and FIG. 6 is an enlarged view of a main part of a cooling plate of the air-cooled fuel cell shown in FIG. As shown in FIG. 5, a conventional air-cooled fuel cell has a cell 54 in which an anode 52 and a cathode 53 are arranged via an electrolyte 51.
And a separator 55 are laminated, and a cooling plate 57 having a plurality of cooling air passages 56 formed therein is inserted in every several cells 54. Here, when the battery reaction (power generation) is performed,
Since the battery temperature rises due to reaction heat and the like caused by cell power generation, it is necessary to cool the battery and operate it at an optimum temperature. Conventionally, air is made to flow from the cooling air passage 56 of the cooling plate 57 to exchange heat with the cells 54 that are power generators to cool the battery. In this case, the reaction heat of the cell 54 is
As shown in FIG. 6, since conduction is performed through the ribs 58 and the like,
The temperature in the cooling air passage 56 is high on the wall surface portion 56a,
It is low at the central portion 56b. Therefore, although the air flowing through the wall surface portion 56a of the cooling air passage 56 is used for heat exchange, the air flowing through the central portion 56b hardly contributes to the heat exchange, which causes a problem of poor heat exchange efficiency.

In order to solve this problem, FIG. 7 and FIG.
There has been proposed a cooling plate having a structure as shown in FIG. FIG. 7 is a plan view of a conventional cooling plate, and FIG. 8 is a sectional view taken along line XX of the cooling plate shown in FIG. The cooling plate 70 has a plurality of cooling air passages 72 partitioned by ribs 71 and fins 73 are provided between the ribs 71. This cooling plate 70 is
The reaction heat of the cells, which has been concentrated on the wall surface portion of the cooling air passage 72, is dispersed to the central portion via the fin 73 which is a heat conductor, so that the cooling air that has hardly contributed to the heat exchange in the past. The air flowing through the center of the passage 72 is used to improve the heat exchange efficiency.

[0004]

However, in the above-described conventional cooling plate 70, the fins 73 provided in each cooling air passage 72 have the downstream portion 7 of the cooling air passage as shown in FIG.
Since it is extended to 2a, the pressure loss when pumping air to the downstream portion 72a becomes large. Therefore, the auxiliary machine power required when air is pressure-fed increases. In the fuel cell, since a part of the electric power obtained by the fuel cell power generation is usually used to drive the auxiliary machine power, an increase in the auxiliary machine power results in a decrease in the power generation efficiency of the fuel cell.

The present invention has been made in view of the above circumstances, and reduces the pressure loss in the cooling plate to reduce the power of the auxiliary machine required when pumping air to the cooling plate, and to generate electricity as a whole. It is an object of the present invention to provide a fuel cell capable of improving efficiency.

[0006]

In order to achieve the above object, the invention of claim 1 forms a cell in which an anode and a cathode are arranged through an electrolyte and an anode gas passage and / or a cathode gas passage. In a fuel cell having a structure in which a separator and a cooling plate having a plurality of cooling air passages partitioned by ribs are inserted every several cells, in the middle part of each cooling air passage of the cooling plate, a A heat conducting member having a low height is extended in parallel with the ribs, and an anode and a cathode are arranged on the upper and lower surfaces of the stack corresponding to the midstream portion of the cooling air passage in which the heat conducting member is extended. It has a feature.

According to the second aspect of the present invention, the cooling plate is composed of at least two plates having different thermal conductivities, and constitutes the upstream portion of the cooling air passage in which the heat conducting member is not provided. It is characterized in that the heat conductivity of the plate is smaller than the heat conductivity of the plate forming the midstream portion of the cooling air passage in which the heat conducting member is provided.

[0008]

According to the structure of the invention of claim 1, the anode and the cathode are arranged on the upper and lower surfaces of the stack corresponding to the midstream portion of the cooling air passage. That is, since neither the anode nor the cathode is arranged at the positions corresponding to the upstream portion and the downstream portion of the cooling air passage, the reaction heat accompanying the cell power generation is concentrated in the middle portion of the cooling air passage, and The reaction heat of the cell is difficult to conduct to the downstream portion. In the invention of claim 1, since the heat conducting member is not provided in the downstream portion of the cooling air passage in which the reaction heat of the cell is difficult to be conducted, when the heat conducting member is extended to the downstream portion as in the conventional case. Compared with, the pressure loss when pumping air is smaller. As a result, the auxiliary machine power required to pump air is also reduced, so that the power generation efficiency of the fuel cell as a whole is improved.

Further, in the upstream portion of the cooling air passage, the reaction heat of the cell is difficult to be conducted as described above, and in addition, relatively low temperature air before contributing to heat exchange flows, so that the temperature becomes too low. According to the invention of claim 2, since the upstream portion of the cooling air passage is formed of the plate having a small thermal conductivity, the reaction heat of the cell in the portion is less likely to escape, and the temperature is reduced accordingly. Suppressed. On the other hand, since the reaction heat of the cell is concentrated and the temperature of the cooling air passage becomes too high, the middle part of the cooling air passage is composed of a plate with higher thermal conductivity than the upstream part, so the reaction heat of the cell at that part escapes. It becomes easier and the temperature rise is suppressed accordingly. These results,
The temperature difference between the cooling plates is suppressed, and the in-plane temperature of the battery is made uniform.

[0010]

1 is a plan view of a cooling plate of a fuel cell according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of an upstream portion and a downstream portion of the cooling plate shown in FIG. FIG. 3 is a sectional view taken along the line BB of the midstream portion of the cooling plate shown in FIG. This cooling plate 1 has a plurality of cooling air passages 3 partitioned by a plurality of ribs 2 at substantially equal intervals,
Upstream portion 3a in the direction of the air flow path of each cooling air passage 3
A fin 4 as a heat conduction member is extended in the middle-flow portion 3c except the downstream portion 3b. As shown in FIG. 3, the fins 4 are formed substantially in the center of the cooling air passages 3 partitioned by the ribs 2 and the height (h) of the fins 4 separates the cooling air passages 3. It is provided so as to be lower than the height (H) of the rib 2 (H>
h). This is because the higher the height (h) of the fins 4 is, the more the pressure loss of the air flowing through the cooling air passage 3 is increased, and the height (h) of the fins 4 is the height (H) of the ribs 2. It is preferable to provide it so as to be about 1/2 of
Further, the material of the fins 4 is not particularly limited, and may be made of the same material as the cooling plate 1 or the ribs 2, or may be made of a material having a thermal conductivity different from those of these.

FIG. 4 shows the cooling plate 1 shown in FIGS.
FIG. 3 is a cross-sectional perspective view (partially broken surface) of a fuel cell using
In this fuel cell, a cell 8 in which an anode 6 and a cathode 7 are arranged via an electrolyte matrix 5 and a bipolar plate 11 in which an anode gas passage 9 and a cathode gas passage 10 are formed are laminated, and one surface is formed. Has a structure in which a cooling plate 1 having a half plate 12 having an anode gas passage 9 bonded thereto and having a half plate 15 having a cathode gas passage 10 bonded to the other surface thereof is inserted every several cells 8. is there.

The cell 8 has a structure in which an anode 6 and a cathode 7 supporting a platinum catalyst on carbon paper are arranged via an electrolyte matrix 5 made of silicon carbide, and gas is provided on the outer peripheral side of the anode 6. An anode shim 13 for sealing is provided, and a cathode shim 14 for sealing gas is provided on the outer peripheral side of the cathode 7 as in the case of the anode shim 13. here,
The anode 6 and the cathode 7 are the middle portion 3c of the cooling air passage in which the fins 4 of the cooling plate 1 shown in FIG. 1 are provided.
Are respectively arranged on the upper and lower surfaces of the stack corresponding to
Anode shims 13 and cathode shims 14 are arranged on the upper and lower surfaces of the stack corresponding to the upstream portion 3a and the downstream portion 3b of the cooling air passage except for the above.

The cooling of the cell in the fuel cell constructed as described above will be described below. As described above, the anode 6 and the cathode 7 are connected to the middle portion 3c of the cooling air passage.
And the upstream portion 3a of the cooling air passage arranged at a position corresponding to
Since it is not arranged at a position corresponding to the downstream portion 3b and the downstream portion 3b, the heat of reaction caused by cell power generation is generated in the middle portion 3c of the cooling air passage.
Concentrate on. Since the fins 4 are extended in the midstream portion 3c of the cooling air passage, the reaction heat is dispersed not only in the wall surface portion of the rib 2 but also in the central portion of the cooling air passage 3.

Next, when air is made to flow from the upstream portion 3a of the cooling air passage, the air flowing through the wall surface of the rib 2 exchanges heat with the wall surface portion of the rib 2 and the air flowing through the central portion of the cooling air passage 3 has the fins. Heat exchange with 4. Therefore, since the air flowing through the central portion of the cooling air passage 3 which has hardly contributed to the heat exchange in the past is used for the heat exchange, the heat exchange efficiency is improved.

Subsequently, the exhaust air after heat exchange in the midstream portion 3c of the cooling air passage is discharged to the outside of the battery through the downstream portion 3b of the cooling air passage. Here, since the fins 4 are not provided in the downstream portion 3b of the cooling air passage, the pressure loss of the exhaust air becomes small. By the way, although the cooling plate 1 is composed of one plate, it may be composed of a plurality of plates having different thermal conductivities, for example.
However, in this case, the thermal conductivity of the plate that constitutes the upstream portion 3a of the cooling air passage in which the fins 4 are not provided is greater than the thermal conductivity of the plate that constitutes the midstream portion 3c of the cooling air passage in which the fins 4 are provided. Also needs to be small. Specifically, the thermal conductivity of the upstream portion 3a of the cooling air passage where the fins 4 are not provided is 40 to 50 Kcal / m. h. The thermal conductivity of the middle portion 3c of the cooling air passage provided with the fins 4 and the downstream portion 3b of the cooling air passage not provided with the fins 4 is 120 to 130 Kcal /
m. h. It is possible to use a cooling plate composed of a carbon plate which is at ° C. With this configuration,
The reaction heat of the cell 8 becomes difficult to escape in the upstream portion 3a of the cooling air passage where the temperature becomes too low, so that the temperature rises, and the reaction heat of the cell 8 easily escapes in the middle portion 3c of the cooling air passage where the temperature becomes too high. Therefore, the temperature decreases. It is also possible to replace the downstream portion 3b of the cooling air passage with a plate having the same thermal conductivity as the upstream portion 3a of the cooling air passage. Although such a cooling plate can be manufactured by a known method, for example, it can be manufactured by a method in which the above-mentioned two kinds of carbon powders are put into a mold and pressed.

Further, according to the above-mentioned embodiment, since the position where the anode 6 and the cathode 7 are provided is shifted to the central portion as compared with the conventional case, the temperature of the low temperature portion of the in-plane temperature of the battery is also shifted to the high temperature side. The temperature difference within the battery surface is suppressed.

[0017]

As described above, according to the first aspect of the present invention, the anode and the cathode are arranged on the upper and lower surfaces of the stack corresponding to the midstream portion of the cooling air passage. That is, since neither the anode nor the cathode is arranged at the positions corresponding to the upstream portion and the downstream portion of the cooling air passage, the reaction heat accompanying the cell power generation is concentrated in the middle portion of the cooling air passage, and The reaction heat of the cell is difficult to conduct to the downstream portion. In the invention of claim 1, since the heat conducting member is not provided in the downstream portion of the cooling air passage in which the reaction heat of the cell is difficult to be conducted, when the heat conducting member is extended to the downstream portion as in the conventional case. Compared with, the pressure loss when pumping air is smaller. As a result, the auxiliary machine power required to pump air is also reduced, so that the power generation efficiency of the fuel cell as a whole is improved.

In addition, in the upstream portion of the cooling air passage, the reaction heat of the cell is difficult to be conducted as described above, and the temperature is too low because relatively low temperature air before it contributes to heat exchange flows. According to the invention of claim 2, since the upstream portion of the cooling air passage is formed of the plate having a small thermal conductivity, the reaction heat of the cell in the portion is less likely to escape, and the temperature is reduced accordingly. Suppressed. On the other hand, since the reaction heat of the cell is concentrated and the temperature of the cooling air passage becomes too high, the middle part of the cooling air passage is composed of a plate with higher thermal conductivity than the upstream part, so the reaction heat of the cell at that part escapes. It becomes easier and the temperature rise is suppressed accordingly. These results,
The temperature difference between the cooling plates is suppressed, and the in-plane temperature of the battery is made uniform.

[Brief description of drawings]

FIG. 1 is a plan view of a cooling plate of a fuel cell according to an exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line AA of the upstream portion and the downstream portion of the cooling plate shown in FIG.

FIG. 3 is a cross-sectional view taken along the line BB of the midstream portion of the cooling plate shown in FIG.

4 is a sectional perspective view (partially broken section) of a fuel cell using the cooling plate shown in FIGS. 1 to 3. FIG.

FIG. 5 is a cross-sectional perspective view of a conventional air-cooled fuel cell.

6 is an enlarged view of a main part of a cooling plate of the air-cooled fuel cell shown in FIG.

FIG. 7 is a plan view of a conventional cooling plate.

8 is a cross-sectional view taken along line XX of the cooling plate shown in FIG.

[Explanation of symbols]

 1 Cooling Plate 2 Rib 3 Cooling Air Passage 4 Heat Conducting Member 5 Electrolyte 6 Anode 7 Cathode 8 Cell 9 Anode Gas Passage 10 Cathode Gas Passage 11 ・ 12 ・ 15 Separator 13 Anode Shim 14 Cathode Shim

Claims (2)

[Claims] 1. A cooling plate having a plurality of cooling air passages which are stacked by stacking a cell in which an anode and a cathode are arranged via an electrolyte and a separator in which an anode gas passage and / or a cathode gas passage is formed, and which are partitioned by ribs. In a fuel cell having a structure in which every several cells are inserted, a heat conducting member having a height lower than that of a rib is provided in parallel with the rib at a midstream portion of each cooling air passage of the cooling plate, and A fuel cell, wherein an anode and a cathode are respectively arranged on the upper and lower surfaces of the stack corresponding to the midstream portion of the cooling air passage through which the heat conduction member is extended. 2. The cooling plate is composed of at least two plates having different thermal conductivities, and the thermal conductivity of the plate constituting the upstream part of the cooling air passage in which the heat conducting member is not provided is 2. The fuel cell according to claim 1, wherein the heat conductivity of the plate is smaller than that of a plate forming a midstream portion of the cooling air passage provided with the conductive member.