JP2008300324A - Fuel cell unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell unit which can control an increase of a passage pressure loss due to vapor condensation in gas and can control a deterioration of battery performance and humidifying performance. <P>SOLUTION: In the fuel cell unit 100, a fuel cell gas passage through which oxidized gas flows and a fuel cell offgas passage through which oxidized offgas flows in a fuel cell stack 1 are inclined downward or horizontal in a flowing direction respectively, and a humidifier gas passage through which the oxidized gas 7b flows and a humidifier offgas passage through which the oxidized offgas 6b flows inside a heat exchanging humidifier 2 are inclined downward or horizontal in a flowing direction respectively, and at least either an oxidized offgas connecting passage through which the oxidized offgas 6b flows or an oxidized gas connecting passage 25 through which the oxidized gas 7b flows, both provided on a connecting board 4, is inclined upward in a flowing direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell unit including a solid polymer fuel cell stack and a total heat exchange type humidifier.

Development of solid polymer fuel cells for stationary and in-vehicle use as an environmentally friendly power source is underway. It is essential that the fuel gas and the oxidizing gas supplied to the fuel cell be humidified so that the electrolyte membrane maintains good ionic conduction.
And a total heat exchange type humidifier that performs heat exchange and humidity exchange between the oxidizing gas after passing through the battery reaction part and the oxidizing gas before passing through the battery reaction part, which is the humidifying means, and the fuel cell stack 2. Description of the Related Art There is known a fuel cell unit that achieves high efficiency, compactness, and low cost by using an integrated structure (see, for example, Patent Document 1).

Japanese Patent No. 3839978

However, in the case of the above fuel cell unit, gas is supplied to any of the gas supply channel, the gas discharge channel, the cell reaction channel, and the total heat exchange channel of the total heat exchanger type humidifier of the fuel cell stack. An upwardly inclined flow path is formed along the flow.
When the partial pressure of water vapor in the gas flowing through the flow path of the fuel cell stack and the total heat exchange type humidifier is close to the saturated vapor pressure, dew condensation of water vapor proceeds if the gas temperature decreases.
When dew condensation occurs in the up-gradient flow path, not only increases in the flow pressure loss and auxiliary power due to flow path blockage etc., but also condensation water stays in the battery reaction part and There was a problem such as a decrease in the performance of the total heat exchange type humidifier.

  An object of the present invention is to solve the above-described problems, and its purpose is to suppress an increase in flow path pressure loss due to water vapor condensation in the gas, and to reduce battery performance and humidification performance. A fuel cell unit that can be suppressed is provided.

  A fuel cell unit according to the present invention includes a polymer electrolyte fuel cell stack in which a plurality of unit cells each having an electrolyte membrane sandwiched between a fuel electrode and an oxygen electrode are stacked and generates power by a cell reaction, and the fuel cell stack. Total heat exchange that is provided through the communication plate and performs heat exchange and humidity exchange between the off-gas containing moisture after passing through the unit cell and the gas before passing through the unit cell through a total heat exchange membrane A fuel cell gas flow path through which the gas flows inside the fuel cell stack and a fuel cell off-gas flow path through which the off gas flows are both down-gradient or horizontal along the flow direction, The humidifier gas flow path through which the gas flows inside the heat exchange humidifier and the humidifier off-gas flow path through which the off gas flow are both down-graded or horizontal along the flow direction, and are connected to the communication plate. Vignetting was one of the least of the gas communicating passage through which off-gas communication passage and the gas the off-gas passes is upwardly inclined in the flow direction.

  According to the fuel cell unit of the present invention, it is possible to suppress an increase in flow path pressure loss due to water vapor condensation in the gas and a decrease in battery performance and humidification performance.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding members and parts will be described with the same reference numerals.
Embodiment 1 FIG.
1 is an overall perspective view of a fuel cell unit 100 according to Embodiment 1 of the present invention, and FIG. 2 is a diagram illustrating an internal portion of a total heat exchange type humidifier (hereinafter abbreviated as a humidifier) 2 in FIG. 3 is a partial longitudinal sectional view taken along the line B, FIG. 3 is a schematic view when the first separator plate 17a of FIG. 2 is seen along the arrow B direction, and FIG. 4 is a second separator plate 17b of FIG. It is the schematic when seeing along the arrow C direction. 3 and 4, the humidifier oxidizing gas channel 19 and the oxidizing off gas channel 20 are omitted.

The fuel cell unit 100 includes a solid polymer fuel cell stack 1 in which a plurality of unit cells each having an electrolyte membrane sandwiched between a fuel electrode and an oxygen electrode are stacked, and after passing through the fuel cell stack 1. A humidifier 2 that performs heat exchange and humidity exchange between the oxidizing off gas and the oxidizing gas before passing through the fuel cell stack 1, and a communication plate 4 that connects the humidifier 2 and the fuel cell stack 1.
The fuel cell stack 1 is configured such that both side surfaces of a battery body in which a plurality of unit cells are stacked are disposed on the first end plate 3a and the upper portion of the communication plate 4 via a first insulating plate 13a and a second insulating plate 13b. Is sandwiched between. A fuel gas supply hole 11 for supplying fuel gas to the unit cell is formed on one side of the upper portion of the first end plate 3a. A fuel gas discharge hole 12 for discharging fuel gas from the unit cell is formed on one side of the lower portion of the first end plate 3a. In addition, a cooling water supply hole 10 that supplies cooling water for cooling the plurality of single cells and a cooling water discharge hole 9 that discharges the cooling water are formed at the lower end of the first end plate 3a. .
The fuel cell gas flow path through which the oxidizing gas flows and the fuel cell off-gas flow path through which the oxidizing off gas flow formed inside the fuel cell stack 1 are both downwardly inclined or horizontal along the flow direction.

  In the humidifier 2, both side surfaces of the humidifier body are sandwiched between the lower part of the communication plate 4 and the second end plate 3 b. The humidifier body is formed by stacking a plurality of humidifying units each having a total heat exchange membrane 18 sandwiched between a first separator plate 17a and a second separator plate 17b. A humidifier oxidizing gas flow path 19 that is a humidifier gas flow path is formed on one surface of the first separator plate 17a, and a humidifier oxidizing off gas flow path 20 that is a humidifier off gas flow path is formed on the other surface. ing. A humidifier oxidizing gas flow path 19 is formed on one surface of the second separator plate 17b, and a humidifier oxidizing off gas flow path 20 is formed on the other surface. The humidifier oxidizing gas channel 19 and the humidifier oxidizing off gas channel 20 are opposed to each other with the total heat exchange membrane 18 interposed therebetween.

A first oxidizing gas manifold 14a is formed at the upper edge of each rectangular first separator plate 17a and each second separator plate 17b. A second oxidizing gas manifold 14b is formed on the diagonal line of the first oxidizing gas manifold 14a at the lower edge of each first separator plate 17a and each second separator plate 17b.
A first oxidizing off-gas manifold 15a is formed at the upper edge of each first separator plate 17a and each second separator plate 17b so as to face the first oxidizing gas manifold 14a. A second oxidizing off-gas manifold 15b is formed at the lower edge of each first separator plate 17a and each second separator plate 17b so as to face the second oxidizing gas manifold 14b.
An oxidizing gas supply hole 5 is formed in the upper part of the second end plate 3b, and an oxidizing off gas discharge hole 8 is formed in the lower part.

  The communication plate 4 extends in the vertical direction inside, and is provided with an oxidizing gas communication passage 25 that communicates the second oxidizing gas manifold 14b and the oxygen electrode of the fuel cell stack 1, and penetrates in the horizontal direction to communicate with the fuel cell stack 1. An oxidizing off-gas communication path is provided in which the oxygen electrode communicates with the first oxidizing off-gas manifold 15a.

Next, the operation of the fuel cell unit 100 having the above configuration will be described assuming that the maximum operating temperature is about 70 ° C. In FIG. 1, the dotted arrow indicates the oxidizing gas before the battery reaction, and the double arrow line indicates the oxidizing off-gas after the battery reaction. The same applies to FIGS. 5 to 10 described later.
The oxidizing gas 7 necessary for the oxygen electrode of the fuel cell stack 1 flows into the first oxidizing gas manifold 14a from the oxidizing gas supply hole 5 of the humidifier 2 at room temperature. The oxidizing gas 7b in the humidifier 2 flows in the horizontal direction while being divided along the first oxidizing gas manifold 14a. As shown in FIG. 3, the diverted oxidizing gas 7 b flows toward the second gas manifold 14 b along the down-gradient and horizontal humidifier oxidizing gas passages 19.
On the other hand, in the humidifier 2, the steam-containing oxidizing off-gas 6a discharged from the oxygen electrode of the fuel cell stack 1 after the cell reaction flows into the oxidizing off-gas manifold 15a. The oxidizing off gas 6b in the humidifier 2 flows in the horizontal direction while being divided along the first oxidizing off gas manifold 15a. As shown in FIG. 4, the divided oxidizing off gas 6 b flows toward the second off gas manifold 15 b along the descending and horizontal oxidizing off gas flow paths 20.

Thus, in the humidifier 2, the oxidizing gas 7 b flowing through the humidifier oxidizing gas channel 19 flows through the oxidizing off-gas channel 20 via the total heat exchange membrane 18, and the oxidizing off-gas 6 b close to saturated steam at about 70 ° C. To receive moisture and receive heat.
The oxidizing gas 7b is heated from room temperature to about 65 ° C. by the heat exchange with the oxidizing off gas 6b through the total heat exchange membrane 18, and is humidified to near the saturated vapor pressure.

The heated and humidified oxidizing gas 7b passes through the second oxidizing gas manifold 14b and flows into the fuel cell stack 1 through the first oxidizing gas communication path 25 provided in the communication plate 4 and extending in the vertical direction. .
The oxidizing gas 7a flowing from the upper part of the fuel cell stack 1 flows in the fuel cell gas flow path in the horizontal direction and the downward gradient in the fuel cell stack 1, and is generated by the cell reaction shown in the following equations (1) and (2). Thus, the oxidizing off gas 6a containing a large amount of water vapor is obtained. The oxidizing off gas 6a flows through the fuel cell off gas flow path in the horizontal direction and the downward gradient, and passes through the oxidizing off gas communication passage penetrating in the horizontal direction of the communication plate 4 from the fuel cell stack 1 to the first oxidizing off gas manifold 15a of the humidifier 2. To be supplied.

(Fuel electrode) H ₂ → 2H ⁺ + 2e ⁻ (1)
(Oxygen electrode) 1/2 O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)

  The oxidizing off gas 6b, which flows into the humidifier 2 and is close to saturated water vapor at about 70 ° C., humidifies and heats the oxidizing gas 7b flowing through the oxidizing off gas channel 20 through the total heat exchange membrane 18, It becomes a gas close to the saturated water vapor partial pressure at about 40 ° C., passes through the second oxidizing off-gas manifold 15 b, and is discharged to the outside from the oxidizing off-gas discharge hole 8.

In the cell reaction, about 49% of the energy consumed in the fuel cell stack 1 is converted into electricity, and the remaining about 51% is converted into heat.
The generated heat is removed by supplying cooling water of about 65 ° C. from the cooling water supply hole 10 into the fuel cell stack 1. In the fuel cell stack 1, the cooling water is distributed to each single cell, removes the generated heat, is heated to about 70 ° C., and is discharged to the outside through the cooling water discharge hole 9. The discharged cooling water is heat-recovered to about 65 ° C. and then circulates through the cooling water supply hole 10.

Incidentally, the communication plate 4 is designed for heat transfer so as to be kept warm by the amount of heat generated by the cell reaction of the fuel cell stack 1. The second insulating plate 13b sandwiched between the communication plate 4 and the unit cell is composed of a combination of a plurality of materials, and the portion adjacent to the region where the temperature of the fuel cell stack 1 is highest is a material having high heat conductivity, such as alumina. And magnesia (about 30 to 50 W / mK) are used, and in the region where the temperature of the fuel cell stack 1 is low, a material having low thermal conductivity, such as polycarbonate resin or polypropylene resin (about 1 to 2 W / mK) is used. .
The communication plate 4 is made of a material having high thermal conductivity, such as stainless steel or aluminum (about 16 to 150 W / mK). As a result, the temperature of the communication plate 4 can be brought close to the maximum temperature of the fuel cell stack 1 (70 ° C. in this embodiment).

In fact, the inventor of the present application obtained a temperature drop in the case where about 17% of the second insulating plate 13b is composed of a high thermal conductivity material and the remaining about 83% is composed of a low thermal conductivity material by experiment. It has been found that the lowering temperature of the communication plate 4 is only about 1 ° C. from the maximum temperature of the fuel cell stack 1.
Therefore, the oxidizing gas 7b close to the saturated water vapor discharged from the humidifier 2 and supplied into the fuel cell stack 1 is blocked by the condensation generated in the oxidizing gas communication path 25 of the communication plate 4 having a vertically upward slope. The fuel cell stack 1 is supplied smoothly to the first oxidizing gas manifold 14a of the fuel cell stack 1 without pulsation.

According to the fuel cell unit 100 according to this embodiment, the fuel cell gas flow path, the fuel cell off-gas flow path, the humidifier oxidant gas flow path 19 and the humidifier oxidant off-gas flow path 20 are all down-gradient along the flow direction. Or, since it is horizontal, even if dew condensation occurs locally for each temperature distribution caused by the cell reaction in the fuel cell stack 1 and the total heat exchange in the humidifier 2, this condensed water Can be discharged promptly.
Accordingly, an increase in flow path pressure loss due to water vapor condensation in the oxidizing gases 7a and 7b and the oxidizing off-gas 6a and 6b is suppressed, and pulsation is prevented.
Moreover, since dew condensation water does not stay in a battery reaction part or a total heat exchange part, the fall of the cell performance of the fuel cell stack 1 or the humidification performance of the humidifier 2 is suppressed.
Furthermore, since the increase in flow path resistance is prevented, the power of the blower can be reduced.

  Further, since the communication plate 4 is made of a material having high thermal conductivity, the oxidizing gas communication passage 25 is heated by heat generated from the fuel cell stack 1 although the oxidizing gas 7b flows vertically upward. In addition, the progress of water vapor condensation in the oxidizing gas communication path 25 can be prevented.

Embodiment 2. FIG.
FIG. 5 is an overall perspective view showing the fuel cell unit 100 of the second embodiment.
In this embodiment, a cooling water discharge hole 9 is formed in the lower end portion of the communication plate 4, and the cooling water flowing into the fuel cell stack 1 from the cooling water supply hole 10 is distributed to each single cell, After removing the generated heat, it passes through the communication plate 4 and is discharged to the outside through the cooling water discharge hole 9.
Other configurations are the same as those of the first embodiment.

  According to the fuel cell unit 100 of the second embodiment, the cooling water at about 70 ° C. that has passed through the fuel cell stack 1 flows through the communication plate 4 as it is, and keeps the communication plate 4 warm.

For example, considering a solid polymer fuel cell unit 100 with an output of 1 kW, the amount of heat required to raise the oxidizing gas 7a from 65 ° C. to 70 ° C. is about 7 J / s. Even if this amount of heat is all covered by cooling water, the temperature drop of the cooling water is only about 0.05 ° C. Therefore, it can be utilized for heat recovery without substantially reducing the temperature of the cooling water.
Actually, the oxidizing gas 7a at 65 ° C. is not raised to 70 ° C. with the cooling water at 70 ° C., and the amount of heat transferred can be about half or less, and the heat due to the temperature drop of the cooling water. The recovery loss is less than 1% of the total recovered heat.
Further, the temperature of the communication plate 4 is approximately 70 ° C., which is the highest temperature of the fuel cell stack 1, and therefore the oxidizing gas 7b discharged from the humidifier 2 and supplied to the fuel cell stack 1 is not condensed. It becomes possible to supply the fuel cell stack 1.

FIG. 6 is an overall perspective view of a fuel cell unit 100 showing another example of the second embodiment.
In the fuel cell unit 100, the fuel cell stack 1 is connected to the lower part on the one surface side of the communication plate 4, and the humidifier 2 is connected to the upper part on the other surface side of the communication plate 4. That is, the vertical positional relationship between the fuel cell stack 1 and the humidifier 2 is opposite to that of the fuel cell unit 100 shown in FIG.
The communication plate 4 is formed with an oxidizing off-gas communication passage 26 extending vertically upward in the interior thereof, and extending in the horizontal direction inside to guide the oxidizing gas 7 b to the oxygen electrode of the fuel cell stack 1. Is formed. A cooling water discharge hole 9 is formed on one side of the upper end portion of the communication plate 4.
Other configurations are the same as those of the fuel cell unit 100 shown in FIG.

In this example, the oxidizing gas 7b heated to about 65 ° C. by the total heat exchange in the humidifier 2 and humidified to near the saturated vapor pressure is oxidized in the second oxidizing gas manifold 14b and the communication plate 4. It passes through the gas communication path, flows in from the upper part of the fuel cell stack 1, and is guided to the oxygen electrode.
The oxidizing gas 7a that has flowed into the fuel cell stack 1 flows through the fuel cell gas flow paths that are horizontal and downward in the fuel cell stack 1, and becomes an oxidizing off gas 6a that contains a large amount of water vapor generated by the cell reaction.
The oxidizing off gas 6a flows through the horizontal and downwardly inclined fuel cell off gas passages, and then flows into the oxidizing off gas communication passage 26 from the lower portion of the communication plate 4. The oxidizing off gas 6a flows vertically upward in the oxidizing off gas communication passage 26 and is supplied to the first oxidizing off gas manifold 15a.
The subsequent flow of the oxidizing off gas 6b in the humidifier 2 is the same as that of the fuel cell unit 100 shown in FIG. 5, and is finally discharged to the outside from the oxidizing off gas discharge hole 8.

According to this fuel cell unit 100, the oxidizing gas 7b discharged from the humidifier 2 and supplied to the fuel cell stack 1 flows through the oxidizing gas communication passage penetrating in the horizontal direction of the communication plate 4 whose temperature is adjusted by cooling water. As a result, the fuel cell stack 1 can be supplied without condensation.
Further, the oxidizing off-gas 6 a containing a large amount of water vapor discharged from the fuel cell stack 1 is directed upward in the vertical direction through the oxidizing off-gas communication passage 26 of the communication plate 4 heated at a temperature substantially equal to the maximum temperature of the fuel cell stack 1. As a result, water condensation does not proceed.
As a result, the humidifier 2 can be disposed above the fuel cell stack 1 in the vertical direction, and a stable fuel cell stack 1 with less pulsation can be obtained.

FIG. 7 is an overall perspective view of a fuel cell unit 100 showing still another example of the second embodiment.
In this example, the humidifier 2 is provided at the lower part of one side of the communication plate 4, and the fuel cell stack 1 is provided at the upper part of the same one side.
The communication plate 4 has an oxidant gas communication passage 25 extending in the vertical direction inside, and an oxidant off-gas communication passage 26 extending in the vertical direction inside, and is cooled on one side of the lower end. Water discharge holes 9 are formed.
Other configurations are the same as those of the fuel cell unit 100 shown in FIG.

According to this fuel cell unit 100, a space is secured on the entire surface of one side of the communication plate 4, and compared with the fuel cell unit 100 shown in FIGS. 1, 5, and 6, the first end. A tightening mechanism (not shown) of the fuel cell stack 1 sandwiched between the upper portions of the plate 3a and the communication plate 4, and a tightening mechanism of the humidifier 2 sandwiched between the second end plate 3b and the lower portion of the communication plate 4 (not illustrated). ) Is easy to design.
In addition, the fuel cell stack 1 and the humidifier 2 can be juxtaposed on the communication plate 4 placed on the floor at the time of manufacture, and the manufacturing process is simplified due to the ease of designing the tightening mechanism. .

Embodiment 3 FIG.
FIG. 8 is an overall perspective view showing the fuel cell unit 100 of the third embodiment.
In the fuel cell unit 100 of this embodiment, the fuel cell stack 1 is provided at the lower part of one side of the communication plate 4, and the humidifier 2 is provided at the upper part of the same one side. That is, the vertical positional relationship between the fuel cell stack 1 and the humidifier 2 is opposite to that of the fuel cell unit 100 shown in FIG.
The communication plate 4 is provided with an oxidizing gas communication passage 25 through which the oxidizing gas flows downward in the vertical direction and an oxidizing off gas communication passage 26 through which the oxidizing off gas flows upward in the vertical direction. A drain discharge hole 24 communicating with the oxidant off-gas communication passage 26 is provided in the lower part of the communication plate 4. From this drain discharge hole 24, the drain stored in the lowermost part of the oxidizing off gas communication path 26 is discharged. A cooling water discharge hole 9 is formed on one side of the upper end portion of the communication plate 4.
Other configurations are the same as those of the fuel cell unit 100 shown in FIG.

According to the fuel cell unit 100, even if the oxidant off-gas 6a contains water that is present as a liquid, the liquid is separated from the drain discharge hole 24 and can prevent the flow path from being blocked by the liquid.
The oxidizing offgas 6a flowing through the oxidizing offgas communication passage 26 of the communication plate 4 is generated by heat generated by the cell reaction in the fuel cell stack 1 and heat from the heated cooling water passing through the communication plate 4. Since the temperature is high and is supplied to the humidifier 2 at a saturated vapor pressure almost equal to the saturated vapor pressure at that temperature, the humidifier 2 performs heat exchange and humidity exchange with high efficiency via the total heat exchange membrane 18. Done.

Embodiment 4 FIG.
FIG. 9 is an overall perspective view showing the fuel cell unit 100 of the fourth embodiment.
In the fuel cell unit 100 of this embodiment, the fuel cell stack 1 and the humidifier 2 are provided in the coaxial line direction with the communication plate 4 interposed therebetween.
The oxidant gas 7b from the humidifier 2 flows into the communication plate 4 and the oxidant gas communication passage 25 that flows in the vertically upward direction and the oxidant off-gas 6a from the fuel cell stack 1 flows in and circulates in the vertically upward direction. An oxidizing off gas communication path 26 is formed.
A cooling water supply hole 10 is provided on the upper one side of the first end plate 3 a, and a cooling water discharge hole 9 is provided on the upper one side of the communication plate 4.
Other configurations are the same as those of the fuel cell unit 100 of FIG.

In this fuel cell unit 100, the oxidizing gas 7b in the humidifier 2 heated to about 65 ° C. by total heat exchange and humidified to near the saturated vapor pressure passes through the second oxidizing gas manifold 14b. In the fuel cell stack 1, it is supplied from the top in the vertical direction as the oxidizing gas 7a.
The oxidizing gas 7a that has flowed in from the upper part of the fuel cell stack 1 flows through the fuel cell gas flow paths that are horizontal and downward in the fuel cell stack 1, and becomes an oxidizing off gas 6a that contains a large amount of water vapor generated by the cell reaction. The oxidizing off gas 6 a is supplied from the fuel cell stack 1 to the first oxidizing off gas manifold 15 a of the humidifier 2 through the fuel cell off gas flow paths of horizontal and downward gradients and the oxidizing off gas communication path 26 of the communication plate 4.
Further, the cooling water from which the amount of heat generated from the fuel cell stack 1 has been removed is discharged from the cooling water discharge hole 9 while keeping the communication plate 4 warm.

  According to this fuel cell unit 100, since the fuel cell stack 1 and the humidifier 2 are provided on the same axis with the communication plate 4 interposed therebetween, a common fastening mechanism is used for the fuel cell stack 1 and the humidifier 2. Thus, the tightening can be performed collectively, the number of members is reduced, and the manufacturing process is simplified.

Embodiment 5. FIG.
FIG. 10 is an overall perspective view showing the fuel cell unit 100 of the fifth embodiment, FIG. 11 is a schematic view showing the surface of the first separator plate 17a on the side in contact with the total heat exchange membrane 18, and FIG. FIG. 13 is a schematic diagram showing the surface of the separator plate 17b on the side in contact with the total heat exchange membrane 18, and FIG. 13 is a correlation diagram between the gas temperature and the saturated vapor pressure. In addition, in FIG.11 and FIG.12, the humidifier oxidizing gas flow path 19 and the oxidizing off gas flow path 20 are abbreviate | omitted.
In this embodiment, as shown in FIG. 11, a first oxidant gas intermediate manifold 22a and a second oxidant gas intermediate manifold 22b are formed on the first separator plate 17a. The second end plate 3b is provided with an oxidizing gas communication channel 16 that communicates the first oxidizing gas intermediate manifold 22a and the second oxidizing gas intermediate manifold 22b. The oxidizing gas communication channel 16, which is a non-contact channel, is a bypass channel that does not contact the total heat exchange membrane 18 in the middle of the humidifier oxidizing gas channel 19.
Further, as shown in FIG. 12, an oxidizing off-gas intermediate manifold 23 is provided between the first oxidizing gas intermediate manifold 22a and the second oxidizing gas intermediate manifold 22b.
Other configurations are the same as those of the fuel cell unit 100 shown in FIG.

In the fuel cell unit 100, the oxidizing gas 7 is supplied from the oxidizing gas supply hole 5 at room temperature in the humidifier 2, and descends from the first oxidizing gas manifold 14 a through the horizontal humidifier oxidizing gas channel 19. It distribute | circulates and distribute | circulates to the 1st oxidizing gas intermediate manifold 22a. Thereafter, the oxidizing gas 7b is caused to flow upward in the vertical direction through the oxidizing gas communication channel 16 provided in the second end plate 3b and supplied to the second oxidizing gas intermediate manifold 22b. Subsequently, the oxidizing gas 7b flows through the second oxidizing gas manifold 14b through the down-gradient and horizontal humidifier oxidizing gas passages 19. That is, the humidifier oxidizing gas channel 19 formed in the humidifier 2 constitutes a U-turn path.
During this time, the oxidizing gas 7b is humidified through the total heat exchange membrane 18 and receives heat by the gas temperature of about 70 ° C. and the oxidizing off-gas 6b of saturated water vapor. This oxidizing off gas 6b flows from the first oxidizing off gas manifold 15a through the oxidizing off gas intermediate manifold 23 and then along the humidifier oxidizing off gas flow path 20 passing through the second oxidizing off gas manifold 15b. The humidifier oxidant off-gas flow path 20 is downwardly inclined and horizontal along the flow direction.
On the other hand, the oxidizing off gas 6b after heating and humidifying the oxidizing gas 7b through the total heat exchange membrane 18 becomes a gas close to a saturated water vapor partial pressure of about 40 ° C., and the second oxidizing off gas manifold 15b. And is discharged to the outside from the oxidizing off gas discharge hole 8.

The oxidizing gas 7b in the humidifier 2 heated to about 65 ° C. by the heat exchange and humidified to near the saturated vapor pressure passes through the second oxidizing gas manifold 14b and is supplied to the communication plate 4. It flows upward in the vertical direction in the communication path 25 and is supplied into the fuel cell stack 1 as an oxidizing gas 7a from above.
The oxidant gas 7a flows along the fuel cell oxidant gas flow paths having horizontal and downward gradients. The oxidizing gas 7a becomes an oxidizing off gas 6a containing a large amount of water vapor generated by the cell reaction in the unit cell, and the oxidizing off gas 6a flows along the horizontal and downward fuel cell oxidizing off gas flow paths. Thereafter, the oxidizing off gas flows vertically upward along the oxidizing off gas communication path 26 provided on the communication plate 4 and is supplied from the fuel cell stack 1 to the first oxidizing off gas manifold 15a.

  The temperature of the communication plate 4 is adjusted by the cooling water supplied to the cooling water supply hole 10 provided in the first end plate 3a. That is, about 65 ° C. cooling water flowing from the cooling water supply hole 10 removes the heat generated in the fuel cell stack 1 and rises to about 70 ° C., then the communication plate 4 is heated to discharge the cooling water. It is discharged from the hole 9.

On the other hand, from the correlation between the temperature and the saturated vapor pressure, the amount of change in the saturated water vapor partial pressure accompanying the temperature change differs between the low gas temperature and the high temperature. As shown in FIG. 13, for example, when the temperature decreases from 65 ° C. to 5 ° C., the water vapor partial pressure decreases by 5.1 kPa, whereas when the temperature decreases from 40 ° C. by 5 ° C., the pressure decreases by 1.8 kPa. . Therefore, the dew condensation rate is about 1/3 even at the same temperature drop.
In this embodiment, the temperature of the oxidizing gas 7b in the humidifier 2 is low, and the oxidizing gas communication channel in which the oxidizing gas 7b is not in contact with the total heat exchange membrane 18 while the ratio of dew condensation is small even at the same temperature drop. The humidifier oxidant gas flow path 19 is circulated in a vertically upward direction via 16 so as to have a horizontal and downward gradient in a region where the temperature is as high as possible.
Therefore, it becomes possible to reduce the influence of moisture condensation, and even if the ratio of the vertical dimension to the horizontal dimension of the total heat exchange membrane 18 in the humidifier 2 is increased, the gas flow path width is appropriately designed. In addition, a plurality of stepped channels (oxidizing gas communication channels 16) can be configured. Therefore, the humidifier 2 matched with the cross-sectional shape of the fuel cell stack 1 is easily designed.

In addition, about the 1st separator plate 17a and the 2nd separator plate 17b, what was shown in FIG.14 and FIG.15 may be sufficient.
The separator plates 17a and 17b are discharged from the fuel cell stack 1 and are converted into saturated water vapor at about 70 ° C., which has been flowing from the first oxidizing off-gas manifold 15a through the horizontal and descending oxidizing off-gas channel 20 by the serpentine channel. The oxidizing gas 7b in the humidifier 2 is humidified and heated through the total heat exchange membrane 18 by the near oxidizing off gas 6b.

  Compared to the separator plates 17a and 17b shown in FIGS. 11 and 12, the separator plates 17a and 17b do not require the oxidation off-gas intermediate manifold 23, and the configuration of the separator plates 17a and 17b is simplified.

  Moreover, although the oxidizing gas communication channel 16 is provided in the second end plate 3b, it may be formed in the separator plate 17a.

In each of the above embodiments, the fuel cell unit that humidifies and heats the oxidizing gas by sending the oxidizing gas sent to the oxygen electrode to the total heat exchange type humidifier has been described. The present invention can also be applied to a fuel cell unit that feeds hydrogen gas to a total heat exchange type humidifier to humidify and heat the hydrogen gas.
Further, in each of the above embodiments, the case where the oxidizing gas 7b and the oxidizing off gas 6b are mainly circulated in the counterflow through the humidifier 2 with the total heat exchange membrane 18 in between has been described in consideration of the heat exchange efficiency. However, of course, it is not limited to this. The flow direction of the oxidizing gas 7b and the oxidizing off gas 6b may be a cross flow, a parallel flow, or a combination thereof.

  Furthermore, although the flow rate of the oxidizing gas 7b flowing vertically upward in the oxidizing gas communication passage 25 and the flow velocity of the oxidizing off gas 6b flowing vertically upward in the oxidation off gas communication passage 26 are not mentioned, the passage area is reduced. Even if dew condensation water is generated, it may be designed to increase the flow speed at which it is blown off.

1 is an overall perspective view showing a fuel cell unit according to Embodiment 1 of the present invention. It is a partial longitudinal cross-sectional view when the total heat exchange type humidifier in FIG. 1 is seen along the arrow A direction. FIG. 3 is a schematic view when the first separator plate of FIG. 2 is viewed along the arrow B direction. FIG. 3 is a schematic view when the second separator plate of FIG. 2 is viewed along the direction of arrow C. It is a whole perspective view which shows the fuel cell unit which concerns on Embodiment 2 of this invention. 6 is an overall perspective view showing another example of a fuel cell unit according to Embodiment 2. FIG. 10 is an overall perspective view showing still another example of the fuel cell unit according to Embodiment 2. FIG. It is a whole perspective view which shows the fuel cell unit which concerns on Embodiment 3 of this invention. It is a whole perspective view which shows the fuel cell unit which concerns on Embodiment 4 of this invention. It is a whole perspective view which shows the fuel cell unit which concerns on Embodiment 5 of this invention. It is the schematic which shows the surface of the side which contacts the total heat exchange film | membrane of the 1st separator plate used for the fuel cell unit of FIG. It is the schematic which shows the surface of the side which contacts the total heat exchange film | membrane of the 2nd separator plate used for the fuel cell unit of FIG. It is a correlation diagram of the temperature and saturated vapor pressure in water. It is the schematic which shows the example different from the 1st separator plate shown in FIG. It is the schematic which shows the example different from the 2nd separator plate shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel cell stack, 2 Total heat exchange type humidifier, 3a 1st end plate, 3b 2nd end plate, 4 communicating plate, 5 Oxidation gas supply hole, 6a Oxidation off gas, 6b Oxidation off gas, 7 Oxidation gas, 7a Oxidized gas, 7b Oxidized gas, 8 Oxidized off-gas discharge hole, 9 Cooling water discharge hole, 10 Cooling water supply hole, 11 Fuel gas supply hole, 12 Fuel gas discharge hole, 13a First insulating plate, 13b Second insulating plate , 14a first oxidizing gas manifold, 14b second oxidizing gas manifold, 15a first oxidizing off gas manifold, 15b second oxidizing off gas manifold, 16 oxidizing gas communication channel (non-contact channel), 17a first Separator plate, 17b Second separator plate, 18 Total heat exchange membrane, 19 Humidifier oxidizing gas flow path (humidifier gas flow path), 20 Humidifier oxidizing off gas flow path Humidifier off-gas flow path), 22a first oxidizing gas intermediate manifold, 22b second oxidizing gas intermediate manifold, 23 oxidizing off-gas intermediate manifold, 24 drain discharge hole, 25 oxidizing gas communication path, 26 oxidizing off gas communication path, 100 fuel Battery unit.

Claims (8)

A solid polymer fuel cell stack in which a plurality of unit cells each having an electrolyte membrane sandwiched between a fuel electrode and an oxygen electrode are stacked, and power is generated by a cell reaction;
Heat exchange and humidity exchange between the off-gas containing moisture after passing through the unit cell and the gas before passing through the unit cell through a total heat exchange membrane provided in the fuel cell stack through a communication plate A total heat exchange type humidifier
The fuel cell gas flow path in which the gas flows inside the fuel cell stack and the fuel cell off-gas flow path in which the off gas flows are both downwardly inclined or horizontal along the flow direction,
The humidifier gas flow path through which the gas flows inside the total heat exchange type humidifier and the humidifier off-gas flow path through which the off gas flows are both down-gradient or horizontal along the flow direction,
Further, at least one of the off-gas communication passage through which the off-gas passes and the gas communication passage through which the gas passes is provided on the communication plate, and the fuel cell unit has an upward slope along the flow direction.   The communication plate is provided with a cooling water passage through which cooling water discharged from the fuel cell stack flows, and the temperature of the communication plate is adjusted by the cooling water after cooling the unit cell. The fuel cell unit according to claim 1.   The fuel cell unit according to claim 1 or 2, wherein the fuel cell stack and the total heat exchange type humidifier are respectively disposed on one side surface of the communication plate.   The fuel cell unit according to any one of claims 1 to 3, wherein the fuel cell stack and the total heat exchange type humidifier are arranged in a coaxial line direction with the communication plate interposed therebetween. .   5. The non-contact flow path having an upward slope along the flow direction is formed in a part of the humidifier gas flow path in a non-contact manner with the total heat exchange membrane. The fuel cell unit according to any one of claims.   The fuel cell unit according to claim 5, wherein the non-contact flow path is a gas communication path formed in the communication plate by detour.   The fuel cell unit according to any one of claims 1 to 6, wherein a drain discharge hole is provided in a lower portion of the gas communication path or the off-gas communication path.   The fuel cell unit according to any one of claims 1 to 7, wherein the gas is an oxidizing gas, and the off-gas is the oxidizing off-gas discharged from the oxygen electrode.

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