JP2000090954A - Fuel cell stack - Google Patents

Abstract

(57) [Summary] An object of the present invention is to reliably prevent unnecessary water from being introduced into a fuel cell stack and to simplify the configuration. A first supply pipe provided on a first end plate of a fuel cell stack and connected to a fuel gas supply flow path, and a second supply pipe connected to an oxidant gas supply flow path. 56, a first discharge pipe 58 connected to the fuel gas discharge flow path 44, and a second discharge pipe 60 connected to the oxidant gas discharge flow path 46. An enlarged portion 68 having a step portion 70 protruding downward is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell stack in which unit fuel cells each composed of a solid polymer electrolyte membrane sandwiched between an anode and a cathode are alternately stacked with separators.

[0002]

2. Description of the Related Art A polymer electrolyte fuel cell is usually composed of a unit fuel cell having an anode and a cathode on both sides of an electrolyte comprising a polymer ion exchange membrane (cation exchange membrane). The fuel cell stack is formed by laminating each other by sandwiching them.

In this type of fuel cell stack, a fuel gas, for example, hydrogen, supplied to an anode electrode is hydrogen-ionized on a catalyst electrode and moves to a cathode electrode via a moderately humidified electrolyte. I do. The electrons generated during that time are taken out to an external circuit and used as DC electric energy. Oxidant gas, for example, oxygen gas or air is supplied to the cathode side electrode,
At the cathode side electrode, the hydrogen ions, the electrons, and oxygen react to generate water.

[0004] In this case, the electrolyte comprising the polymer ion exchange membrane must be sufficiently humidified to maintain ion permeability. Therefore, generally, the oxidizing gas and the fuel gas are humidified by using a gas humidifying device provided outside the fuel cell, and the oxidizing gas and the fuel gas are sent to the fuel cell stack as steam to humidify the electrolyte. It is configured as follows.

[0005]

Since the operating temperature of the polymer electrolyte fuel cell is relatively low (up to 100 ° C.), the moisture supplied to the oxidizing gas or the fuel gas for humidification is not sufficient for the fuel cell. There is a risk of dew condensation in the piping before being introduced into the battery stack. On the other hand, water that has not been absorbed by the electrolyte after being introduced into the fuel cell stack, or water generated by the reaction is cooled in the pipe after being discharged from the gas flow path or the fuel cell stack in the fuel cell stack,
It is easy to exist in water.

However, as described above, when water is present in the piping near the fuel cell stack or in the gas flow path in the fuel cell stack, the oxidizing gas or the fuel gas is sufficiently supplied to each unit fuel cell. It becomes difficult. As a result, it has been pointed out that the diffusibility of the fuel gas and the oxidizing gas, which are reaction gases, into the catalyst electrode layer is reduced, and the cell performance is significantly deteriorated.

The present invention solves this kind of problem, and provides a fuel cell stack capable of reliably preventing unnecessary water from being introduced into the fuel cell stack and simplifying the configuration. The purpose is to:

[0008]

In a fuel cell stack according to the present invention, first and second supply pipes connected to inlets of a fuel gas flow path and an oxidizing gas flow path in the fuel cell stack; First and second exhaust pipes connected to outlets of the fuel gas flow path and the oxidizing gas flow path, and at least one pipe protrudes below a part of the pipe line from the other part. An enlarged portion having a step portion is provided.

Here, a humidified gas having a dew point equal to or lower than a cooling water temperature (stack temperature) is supplied to the fuel cell stack in order to prevent dew condensation. However, if there is a temperature difference between the pipe portion and the stack temperature, condensation of water vapor occurs in the pipe portion, and condensed water may be introduced into the fuel cell stack. In this case, in the present invention, a step portion projecting downward is formed in the enlarged portion provided in the first supply pipe or the second supply pipe, and water condensed in the pipe is stored in the step portion. Therefore, it is possible to reliably prevent unnecessary water from being introduced into the gas flow path in the fuel cell stack.

On the other hand, water condensed in a pipe communicating with the gas outlet side of the fuel cell stack may flow back into the fuel cell stack. At this time, in the present invention, by providing an enlarged portion in the first discharge pipe and the second discharge pipe, water in the pipe is stored in a step portion of the enlarged portion, and thus the water in the gas flow path in the fuel cell stack is stored. It is possible to effectively prevent the backflow of water.

Further, according to the present invention, at least one of a first supply pipe, a second supply pipe, a first discharge pipe, and a second discharge pipe connected to the inlet and the outlet of the fuel gas flow path and the oxidant gas flow path. One is provided with an inclined portion that is inclined upward toward the fuel cell stack. For this reason, the water condensed in the first supply pipe and the second supply pipe is not introduced into the fuel cell stack by the inclined portion, while the water condensed in the first discharge pipe and the second discharge pipe is prevented. However, backflow into the fuel cell stack can be reliably prevented.

[0012]

FIG. 1 is a schematic perspective explanatory view of a fuel cell stack 10 according to a first embodiment of the present invention.
FIG. 2 is an explanatory cross-sectional view of a main part of the fuel cell stack 10, and FIG. 3 is a partially exploded perspective explanatory view of the fuel cell stack 10.

The fuel cell stack 10 includes a unit fuel cell 12 and first and second separators 14 and 16 sandwiching the unit fuel cell 12, and a plurality of these units are stacked as needed. I have. The unit fuel cell 12 includes a solid polymer electrolyte membrane 18 and this electrolyte membrane 18.
, And an anode-side electrode 20 and a cathode-side electrode 22 disposed therebetween.

As shown in FIG. 3, the unit fuel cells 12
First and second gaskets 24 and 26 are provided on both sides of the anode electrode 2.
The second gasket 26 has a large opening 30 for accommodating the cathode 22 while the second gasket 26 has a large opening 28 for accommodating the cathode electrode 22. The unit fuel cell 12 and the first and second gaskets 24 and 26
And the second separators 14 and 16, and a plurality of these are stacked in the horizontal direction. First and second end plates 32 and 34 are provided at both ends of the unit fuel cell 12 and the first and second separators 14 and 16 in the stacking direction.
Are disposed, and the first and second end plates 32 and 34 are integrally fastened and fixed via a tie rod 36.

In the fuel cell stack 10, a fuel gas supply passage 38, an oxidizing gas supply passage 40 and a cooling water discharge passage 42 are integrally formed on the upper side, and the fuel gas supply passage 38 and the cooling water discharge passage 42 are formed on the lower side. Gas discharge channel 44, oxidant gas discharge channel 4
6 and the cooling water supply channel 48 are integrally formed.

The anode electrode 20 of the first separator 14
A first flow path 50 is formed on the surface facing the first flow path 50 so as to communicate with the fuel gas supply flow path 38 and the fuel gas discharge flow path 44 and extend vertically. On the surface of the second separator 16 facing the cathode-side electrode 22, a second flow path 52 extending in the vertical direction is formed so as to communicate the oxidizing gas supply flow path 40 and the oxidizing gas discharge flow path 46. (See FIG. 2). On the other surface of each of the first and second separators 14 and 16,
A third flow path 53 extending in the vertical direction is formed by connecting the cooling water discharge flow path 42 and the cooling water supply flow path 48.

As shown in FIG. 1, the first end plate 3
2 includes a first supply pipe 54 connected to the fuel gas supply flow path 38, a second supply pipe 56 connected to the oxidant gas supply flow path 40, and a second supply pipe 56 connected to the fuel gas discharge flow path 44. 1
A discharge pipe 58, a second discharge pipe 60 connected to the oxidizing gas discharge flow path 46, a cooling water discharge pipe 62 connected to the cooling water discharge flow path 42, and a cooling water supply flow path 48. A cooling water supply pipe 64 is provided.

As shown in FIG. 2, the first supply pipe 54
A pipe 66 connected to a fuel gas supply source (not shown) is provided, and an enlarged portion 68 is provided in the pipe 66 near the first end plate 32. The enlarged portion 68 has a stepped portion 70 protruding below the conduit 66, and is actually set in a cylindrical shape in which the opening diameter of the conduit 66 is enlarged. The second supply pipe 56, the first discharge pipe 58, and the second discharge pipe 60 are configured similarly to the first supply pipe 54, and the same components are denoted by the same reference characters and are described in detail. Detailed description is omitted.

The fuel cell stack 1 thus configured
The operation of 0 will be described below.

A hydrogen gas (fuel gas) containing water vapor in advance is supplied from a first supply pipe 54 connected to the first end plate 32 to the fuel gas supply passage 38, and a second supply pipe is provided. Oxidant gas supply channel 4 from 56
Air (or oxygen gas), which is an oxidizing gas containing water vapor with respect to 0, is supplied.

The hydrogen gas introduced into the fuel gas supply channel 38 is supplied to the anode 20 of the unit fuel cell 12 while moving downward along the first channel 50.
On the other hand, the air introduced into the oxidizing gas supply flow path 40 is similarly supplied to the cathode electrode 22 constituting the unit fuel cell 12 while moving downward along the second flow path 52. Thereby, the hydrogen gas is ionized by hydrogen and moves toward the cathode 22 through the electrolyte membrane 18,
The unit fuel cell 12 generates power. Unused hydrogen gas is supplied from the fuel gas discharge passage 44 to the first discharge pipe 5.
8 and unused air is led out of the oxidizing gas discharge passage 46 to the second discharge pipe 60.

The cooling water supply channel 48 is supplied with cooling water from a cooling water supply pipe 64. This cooling water is supplied to the third flow path 5 of the first and second separators 14 and 16.
After cooling each unit fuel cell 12 by flowing through the cooling water 3, the fuel cell 12 is led out to the cooling water discharge pipe 62.

By the way, for example, hydrogen gas containing steam for electrolyte humidification is supplied to the first supply pipe 54 in advance, and the first supply pipe 54 and the stack temperature of the fuel cell stack 10 (cooling water) are supplied. When a temperature difference occurs in the first supply pipe 54, condensation of water vapor occurs in the first supply pipe 54. Then, the condensed water tends to move into the fuel cell stack 10 along the flow of the hydrogen gas.

In this case, in the first embodiment, as shown in FIG. 2, the pipe 66 forming the first supply pipe 54
An enlarged portion 68 is provided near the end plate 32, and a step portion 70 is formed in the enlarged portion 68 so as to project downward from the pipe 66. For this reason,
The water 72 condensed in the first supply pipe 54 is transferred to the step 70
And flowing to the fuel gas supply flow path 38 in the fuel cell stack 10 can be prevented. This reliably prevents the water 72 condensed in the first supply pipe 54 from entering and staying in the fuel cell stack 10 and hindering uniform distribution of hydrogen gas to each unit fuel cell 12. Absent.

On the other hand, the water 7 condensed in the first discharge pipe 58
Similarly, the enlarged portion 6 forming the first discharge pipe 58
8 and can be reliably prevented from flowing back into the fuel cell stack 10. As a result, there is obtained an effect that unnecessary water 72 is not introduced into the fuel cell stack 10 and the fuel cell stack 10 can be stably operated for a long time.

Similarly, also in the second supply pipe 56 and the second discharge pipe 60 for introducing and discharging air,
Condensed water 72 is not introduced into fuel cell stack 10. In the first embodiment, the first and second supply pipes 54 and 56 and the first and second discharge pipes 58,
Although the enlarged portions 68 are provided on the respective portions 60 and 60, it is not necessary to provide the enlarged portions 68 in portions where there is no concern about condensation of water vapor, and the enlarged portions 68 can be selectively employed.

FIG. 4 is a schematic perspective explanatory view of a fuel cell stack 80 according to a second embodiment of the present invention, and FIG.
FIG. 3 is an explanatory sectional view of a main part of the fuel cell stack 80. Note that the same components as those of the fuel cell stack 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The first end plate 82 constituting the fuel cell stack 80 has a first supply pipe 84 connected to the fuel gas supply passage 38 and a second supply pipe connected to the oxidant gas supply passage 40. 86, a first discharge pipe 88 connected to the fuel gas discharge flow path 44, and an oxidizing gas discharge flow path 46.
And a second discharge pipe 90 connected to the second discharge pipe 90. In the second embodiment, at least one of the first and second supply pipes 84 and 86 and the first and second discharge pipes 88 and 90 has a slope that is inclined upwards generally toward the fuel cell stack 80. A portion 92 is provided.

In the second embodiment configured as described above, for example, even if water vapor in the hydrogen gas flowing in the first supply pipe 84 condenses to generate water in the first supply pipe 84, Due to the inclination of the inclined portion 92 that is inclined upward toward the fuel cell stack 80, condensed water does not move into the fuel cell stack 80. On the other hand, the first discharge pipe 88 from which unused hydrogen gas is discharged from the fuel cell stack 10 also has an inclined portion 92. Therefore,
The water condensed in the first discharge pipe 88 forms the fuel cell stack 8
It is possible to reliably prevent backflow into zero.

As a result, in the second embodiment, the same effects as those of the first embodiment can be obtained, for example, the fuel cell stack 80 can be stably operated for a long time with a simple configuration.

FIG. 6 is a partially sectional explanatory view of a fuel cell stack 100 according to a third embodiment of the present invention. In addition,
The same components as those of the fuel cell stack 10 according to the first embodiment are denoted by the same reference numerals, and a detailed description thereof will be omitted.

The fuel cell stack 100 includes first and second supply pipes 54 and 56 and first and second discharge pipes 5.
8 and 60, and the respective drain pipes 102a
They are connected to the liquid reservoirs 104a to 104d through 102 to 102d. Water level meters 106a to 106d for detecting the water level of the water 72 stored in the liquid reservoirs 104a to 104d, respectively.
106d, and discharge valves 108a to 108d for discharging the water 72 when the water level meters 106a to 106d determine that a certain amount or more of the water 72 is stored in the liquid reservoirs 104a to 104d. Provided.

In the third embodiment configured as described above, for example, the water 72 condensed in the first supply pipe 54 for supplying hydrogen gas into the fuel cell stack 100 is
It is stored in the liquid reservoir 104a via the drain pipe 102a. In the liquid reservoir 104a, the water level of the water 72 is measured via a water level meter 106a. When the water level is equal to or more than a certain amount, the discharge valve 108a is opened to open the liquid reservoir 104a.
The water 72 inside is automatically discharged. Next, the liquid pool 1
When the water level in the nozzle 04a reaches the lower limit, the discharge valve 108
a is closed, and the automatic drainage processing ends.

As described above, in the third embodiment, the water condensed in the first supply pipe 54 is temporarily removed from the liquid pool 104a.
After that, the water is automatically drained through the discharge valve 108a. Therefore, there is an advantage that unnecessary water 72 is prevented from being introduced into the fuel cell stack 100, and that the fuel cell stack 100 can be stably and continuously operated for a longer time.

FIG. 7 is a partially sectional explanatory view of a fuel cell stack 120 according to a fourth embodiment of the present invention. In addition,
The same components as those of the fuel cell stack 100 according to the third embodiment are denoted by the same reference numerals, and a detailed description thereof will be omitted.

In this fuel cell stack 120, the first and second supply pipes 54, 56 and the first and second discharge pipes 58, 60 are provided with an inclined portion 122 which is inclined upward toward the fuel cell stack 120. ing. Therefore, the fourth
According to the embodiment, the water 72 can be reliably prevented from being unnecessarily introduced into the fuel cell stack 120 via the step portion 70 and the inclined portion 122, and the same effects as those of the third embodiment can be obtained. Is obtained.

[0037]

In the fuel cell stack according to the present invention, the first and second supply pipes and the first and second discharge pipes connected to the fuel gas flow path and the oxidizing gas flow path in the fuel cell stack. At least one of them has an enlarged portion having a step portion projecting downward from the other portion of the pipeline in a part of the pipeline, and water condensed in the pipeline is accumulated in the step portion. , Are not introduced into the fuel cell stack. Thus, the fuel cell stack can be stably operated for a long time with a simple configuration.

According to the present invention, at least one of the first and second supply pipes and the first and second discharge pipes connected to the fuel gas flow path and the oxidizing gas flow path of the fuel cell stack includes the fuel An inclined portion that is inclined upward toward the battery stack is provided. For this reason, the water condensed in the pipeline is not sent into the fuel cell stack or does not flow back into the fuel cell stack, and the power generation performance of the fuel cell stack can be effectively maintained. Become.

[Brief description of the drawings]

FIG. 1 is a schematic perspective explanatory view of a fuel cell stack according to a first embodiment of the present invention.

FIG. 2 is an explanatory sectional view of a main part of the fuel cell stack.

FIG. 3 is a partially exploded perspective view of the fuel cell stack.

FIG. 4 is a schematic perspective view illustrating a fuel cell stack according to a second embodiment of the present invention.

FIG. 5 is an explanatory sectional view of a main part of the fuel cell stack shown in FIG. 4;

FIG. 6 is a partially sectional explanatory view of a fuel cell stack according to a third embodiment of the present invention.

FIG. 7 is a partially sectional explanatory view of a fuel cell stack according to a fourth embodiment of the present invention.

[Explanation of symbols]

10, 80, 100, 120: fuel cell stack 12: unit fuel cell 14, 16, separator 18: electrolyte membrane 20: anode electrode 22: cathode electrode 24, 26: gasket 32, 34, 82 ... end plate 38 ... Fuel gas supply flow path 40 ... Oxidizing gas supply flow path 42 ... Cooling water discharge flow path 44 ... Fuel gas discharge flow path 46 ... Oxidizing gas discharge flow path 48 ... Cooling water supply flow path 50, 52, 53
... Flow paths 54, 56, 84, 86 ... Supply pipes 58, 60, 8
8, 90: discharge pipe 62: cooling water discharge pipe 64: cooling water supply pipe 68: enlarged portion 70: stepped portion 92, 122: inclined portion 104a to 104
d: liquid retaining portion 106a to 106d: water level meter 108a to 108
d ... discharge valve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Manabu Tanaka 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda Research Institute Co., Ltd. (72) Yosuke Fujii 1-4-1 Chuo, Wako-shi, Saitama Co., Ltd. Inside Honda R & D Co., Ltd. (72) Inventor Shuji Sato 1-4-1 Chuo, Wako City, Saitama F Honda Co., Ltd. F-term (reference) 5H026 AA06 CC08 CX06 HH03

Claims (2)

[Claims] 1. A unit fuel cell comprising a solid polymer electrolyte membrane sandwiched between an anode electrode and a cathode electrode, and separators are alternately stacked in a horizontal direction, and a fuel gas is supplied to the anode electrode. A fuel gas flow channel, and an oxidizing gas flow channel for supplying an oxidizing gas to the cathode side electrode, wherein the fuel gas flow channel is provided on an end plate of the fuel cell stack. First and second supply pipes connected to the passage and the inlet side of the oxidizing gas flow path; and provided on the end plate, connected to the outlet side of the fuel gas flow path and the oxidizing gas flow path. A first and a second discharge pipe, wherein at least one of the first supply pipe, the second supply pipe, the first discharge pipe, and the second discharge pipe is one of a pipe line. Fuel cell stack and providing a larger portion having a step portion projecting downward than the other portions in minutes. 2. A fuel gas comprising: a fuel cell for supplying a fuel gas to the anode; and a unit fuel cell comprising a solid polymer electrolyte membrane sandwiched between an anode and a cathode; A fuel cell stack provided with a flow path and an oxidizing gas flow path for supplying an oxidizing gas to the cathode electrode, provided on an end plate of the fuel cell stack, the fuel gas flow path and the First and second supply pipes connected to the inlet side of the oxidizing gas flow path; and first and second supply pipes provided on the end plate and connected to outlet sides of the fuel gas flow path and the oxidizing gas flow path. A second discharge pipe, wherein at least one of the first supply pipe, the second supply pipe, the first discharge pipe, and the second discharge pipe is the fuel cell stack. Fuel cell stack, characterized by providing an inclined portion inclined upwardly toward.