JP4456188B2 - Fuel cell stack - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell stack in which unit fuel cells and separators each having a solid polymer electrolyte membrane sandwiched between an anode electrode and a cathode electrode are alternately stacked.
[0002]
[Prior art]
In the polymer electrolyte fuel cell, a unit fuel cell in which an anode electrode and a cathode electrode are arranged on both sides of an electrolyte composed of a polymer ion exchange membrane (cation exchange membrane) is usually sandwiched between separators. The fuel cell stack is formed by stacking each other.
[0003]
In this type of fuel cell stack, a fuel gas, for example, hydrogen supplied to the anode side electrode is hydrogen ionized on the catalyst electrode and moves to the cathode side electrode side through an appropriately humidified electrolyte. Electrons generated in the meantime are taken out to an external circuit and used as direct current electric energy. Since the oxidant gas, for example, oxygen gas or air is supplied to the cathode side electrode, water reacts with the hydrogen ions, the electrons and oxygen to generate water.
[0004]
In this case, the electrolyte made of the polymer ion exchange membrane needs to be sufficiently humidified to maintain ion permeability. For this reason, in general, the oxidant gas and the fuel gas are humidified using a gas humidifier provided outside the fuel cell, and these are sent to the fuel cell stack as water vapor to humidify the electrolyte. It is configured as follows.
[0005]
[Problems to be solved by the invention]
By the way, since a solid polymer fuel cell has a relatively low operating temperature (up to 100 ° C.), before the moisture supplied to the oxidant gas or fuel gas for humidification is introduced into the fuel cell stack, piping is performed. There is a risk of condensation inside. On the other hand, moisture that has not been absorbed by the electrolyte after being introduced into the fuel cell stack or moisture generated by the reaction is cooled in the pipe after being discharged from the gas flow path in the fuel cell stack or the fuel cell stack, It tends to exist in the water state.
[0006]
However, as described above, if water is present in the piping near the fuel cell stack or in the gas flow path in the fuel cell stack, it is difficult to sufficiently supply the oxidant gas and fuel gas to each unit fuel cell. Become. Thereby, the problem that the diffusibility to the catalyst electrode layer of the fuel gas and oxidant gas which are reaction gas falls and the cell performance deteriorates remarkably is pointed out.
[0007]
The present invention solves this type of problem, and it is an object of the present invention to provide a fuel cell stack that can reliably prevent unnecessary water from being introduced into the fuel cell stack and can be simplified in configuration. And
[0008]
[Means for Solving the Problems]
In the fuel cell stack according to the present invention, the first and second supply pipes connected to the inlet side of the fuel gas channel and the oxidant gas channel in the fuel cell stack, the fuel gas channel and the oxidant The first and second exhaust pipes connected to the outlet side of the gas flow path, and at least one pipe has an enlarged portion having a stepped portion projecting downward from the other part in a part of the pipe itself. Provided.
[0009]
Here, the fuel cell stack is supplied with humidified gas having a dew point equal to or lower than the cooling water temperature (stack temperature) in order to prevent 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 the condensed water may be introduced into the fuel cell stack. In that case, in this invention, the level difference part which protrudes below is formed in the enlarged part provided in the 1st supply piping or the 2nd supply piping, and the water condensed in the piping is stored in the level difference part. Therefore, it is possible to reliably prevent unnecessary water from being introduced into the gas flow path in the fuel cell stack.
[0010]
On the other hand, the water condensed in the piping communicating with the gas outlet side of the fuel cell stack may flow backward into the fuel cell stack. At this time, in the present invention, by providing the first discharge pipe and the second discharge pipe with the enlarged portion, the water in the pipe is stored in the stepped portion of the enlarged portion. It is possible to effectively prevent water from flowing backward.
[0011]
In the present invention, at least one of the first supply pipe, the second supply pipe, the first discharge pipe, and the second discharge pipe connected to the inlet and the outlet of the fuel gas channel and the oxidant gas channel is a fuel. An inclined portion that is inclined upward toward the battery stack is provided. For this reason, 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 water condensed in the first discharge pipe and the second discharge pipe. However, it can be reliably prevented from flowing back into the fuel cell stack.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
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 a cross-sectional explanatory view of a main part of the fuel cell stack 10, and FIG. 3 is a partially exploded perspective view of the battery stack 10. FIG.
[0013]
The fuel cell stack 10 includes a unit fuel cell 12 and first and second separators 14 and 16 that sandwich the unit fuel cell 12, and a plurality of sets of these are stacked as necessary. The unit fuel cell 12 includes a solid polymer electrolyte membrane 18, and an anode side electrode 20 and a cathode side electrode 22 that are disposed with the electrolyte membrane 18 interposed therebetween.
[0014]
As shown in FIG. 3, first and second gaskets 24 and 26 are provided on both sides of the unit fuel cell 12, and the first gasket 24 has a large opening 28 for accommodating the anode side electrode 20. On the other hand, the second gasket 26 has a large opening 30 for accommodating the cathode side electrode 22. The unit fuel cell 12 and the first and second gaskets 24 and 26 are sandwiched between the first and second separators 14 and 16, and a plurality of these are stacked in the horizontal direction. First and second end plates 32, 34 are disposed at both ends of the unit fuel cell 12 and the first and second separators 14, 16 in the stacking direction, and the first and second end plates are interposed via tie rods 36. 32 and 34 are fastened and fixed integrally.
[0015]
In the fuel cell stack 10, a fuel gas supply channel 38, an oxidant gas supply channel 40 and a cooling water discharge channel 42 are integrally formed on the upper side, and a fuel gas discharge channel is formed on the lower side. The passage 44, the oxidizing gas discharge passage 46, and the cooling water supply passage 48 are integrally formed.
[0016]
A first flow path 50 that extends in the vertical direction is formed on the surface of the first separator 14 that faces the anode-side electrode 20 and communicates with the fuel gas supply flow path 38 and the fuel gas discharge flow path 44. A second channel 52 that extends in the vertical direction is formed on the surface of the second separator 16 that faces the cathode side electrode 22 and communicates with the oxidant gas supply channel 40 and the oxidant gas discharge channel 46. (See FIG. 2). A third flow path 53 that extends in the up-down direction is formed on the other surface portion of each of the first and second separators 14 and 16 so as to communicate with the cooling water discharge flow path 42 and the cooling water supply flow path 48. .
[0017]
As shown in FIG. 1, the first end plate 32 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, A first discharge pipe 58 connected to the fuel gas discharge passage 44, a second discharge pipe 60 connected to the oxidant gas discharge passage 46, and a cooling water discharge pipe 62 connected to the cooling water discharge passage 42. And a cooling water supply pipe 64 connected to the cooling water supply channel 48 is provided.
[0018]
As shown in FIG. 2, the first supply pipe 54 includes a pipe line 66 connected to a fuel gas supply source (not shown), and an enlarged portion 68 is provided in the vicinity of the first end plate 32 of the pipe line 66. The enlarged portion 68 has a stepped portion 70 that protrudes downward from the pipeline 66, and is actually set in a cylindrical shape in which the opening diameter of the pipeline 66 is enlarged. The second supply pipe 56, the first discharge pipe 58, and the second discharge pipe 60 are configured in the same manner as the first supply pipe 54, and the same components are denoted by the same reference numerals and their details are described. The detailed explanation is omitted.
[0019]
The operation of the fuel cell stack 10 configured as described above will be described below.
[0020]
Hydrogen gas (fuel gas) containing water vapor is supplied in advance from the first supply pipe 54 connected to the first end plate 32 to the fuel gas supply flow path 38 and oxidized from the second supply pipe 56. Air (or oxygen gas), which is an oxidant gas containing water vapor, is supplied to the agent gas supply channel 40.
[0021]
The hydrogen gas introduced into the fuel gas supply channel 38 is supplied to the anode electrode 20 of the unit fuel cell 12 while moving downward along the first channel 50. On the other hand, the air introduced into the oxidant gas supply channel 40 is similarly supplied downward to the cathode side electrode 22 constituting the unit fuel cell 12 while moving downward along the second channel 52. As a result, the hydrogen gas is hydrogen ionized and moves to the cathode side electrode 22 side through the electrolyte membrane 18, and power is generated in the unit fuel cell 12. Unused hydrogen gas is sent from the fuel gas discharge passage 44 to the first discharge pipe 58, and unused air is led out from the oxidant gas discharge passage 46 to the second discharge pipe 60.
[0022]
The cooling water supply channel 48 is supplied with cooling water from a cooling water supply pipe 64. The cooling water flows through the third flow path 53 of the first and second separators 14 and 16 to cool each unit fuel cell 12 and then is led out to the cooling water discharge pipe 62.
[0023]
By the way, for example, hydrogen gas containing water vapor for electrolyte humidification is supplied to the first supply pipe 54 in advance, and the stack temperature (cooling water temperature) between the first supply pipe 54 and the fuel cell stack 10 is set. When the temperature difference occurs, condensation of water vapor is caused in the first supply pipe 54. The condensed water tends to move into the fuel cell stack 10 along the flow of hydrogen gas.
[0024]
In this case, in the first embodiment, as shown in FIG. 2, the pipeline 66 constituting the first supply pipe 54 is provided with an enlarged portion 68 positioned in the vicinity of the first end plate 32, and this enlarged portion. 68 is formed with a stepped portion 70 projecting downward from the conduit 66. For this reason, it is possible to prevent the water 72 condensed in the first supply pipe 54 from collecting in the stepped portion 70 and flowing into the fuel gas supply flow path 38 in the fuel cell stack 10. 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.
[0025]
On the other hand, the water 72 condensed in the first discharge pipe 58 is similarly stored in the enlarged portion 68 constituting the first discharge pipe 58 and reliably prevented from flowing back into the fuel cell stack 10. it can. As a result, 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.
[0026]
Similarly, the condensed water 72 is not introduced into the fuel cell stack 10 in the second supply pipe 56 and the second discharge pipe 60 that introduce and lead out air. In the first embodiment, the enlarged portions 68 are provided in the first and second supply pipes 54 and 56 and the first and second discharge pipes 58 and 60, respectively. However, in the portion where the condensation of water vapor is not a concern. There is no need to provide the enlarged portion 68, and the enlarged portion 68 can be selectively employed.
[0027]
FIG. 4 is a schematic perspective view of a fuel cell stack 80 according to the second embodiment of the present invention, and FIG. 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 is omitted.
[0028]
The first end plate 82 constituting the fuel cell stack 80 includes a first supply pipe 84 connected to the fuel gas supply flow path 38, a second supply pipe 86 connected to the oxidant gas supply flow path 40, A first discharge pipe 88 connected to the fuel gas discharge flow path 44 and a second discharge pipe 90 connected to the oxidant gas discharge flow path 46 are provided. 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 is inclined to incline upwards toward the fuel cell stack 80 as a whole. A portion 92 is provided.
[0029]
In the second embodiment configured as described above, for example, even when water vapor in the hydrogen gas flowing in the first supply pipe 84 condenses and water is generated in the first supply pipe 84, the fuel cell stack. Due to the inclination of the inclined portion 92 that inclines upward toward 80, the condensed water does not move into the fuel cell stack 80. On the other hand, the first discharge pipe 88 through which unused hydrogen gas is discharged from the fuel cell stack 10 similarly has an inclined portion 92. Therefore, it is possible to reliably prevent the water condensed in the first discharge pipe 88 from flowing back into the fuel cell stack 80.
[0030]
Thereby, in 2nd Embodiment, the effect similar to 1st Embodiment is acquired, such as being able to drive the fuel cell stack 80 stably for a long time with a simple structure.
[0031]
FIG. 6 is a partial cross-sectional explanatory view of a fuel cell stack 100 according to the third embodiment of the present invention. 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 is omitted.
[0032]
The fuel cell stack 100 includes first and second supply pipes 54 and 56, and first and second discharge pipes 58 and 60, and is connected to the liquid reservoirs 104a to 104d through drain pipes 102a to 102d, respectively. Has been. In the liquid reservoirs 104a to 104d, water level gauges 106a to 106d for detecting the water level of the stored water 72, and a certain amount or more of water 72 is stored in the liquid reservoirs 104a to 104d by the water level gauges 106a to 106d. When it is determined that the water 72 is discharged, discharge valves 108a to 108d for discharging the water 72 are provided.
[0033]
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 stored in the liquid reservoir through the drain pipe 102a. It is stored in 104a. In the liquid reservoir 104a, the water level of the water 72 is measured via the water level gauge 106a. When the water level is a certain amount or more, the discharge valve 108a is opened and the water 72 in the liquid reservoir 104a is automatically supplied. To be discharged. Next, when the water level in the liquid reservoir 104a reaches the lower limit value, the discharge valve 108a is closed again, and the automatic drainage process ends.
[0034]
Thus, in the third embodiment, the water condensed in the first supply pipe 54 is once stored in the liquid reservoir 104a and then automatically drained through the discharge valve 108a. Therefore, there are advantages 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 operated continuously for a longer time.
[0035]
FIG. 7 is a partial cross-sectional explanatory view of a fuel cell stack 120 according to the fourth embodiment of the present invention. Note that the same components as those of the fuel cell stack 100 according to the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0036]
In the fuel cell stack 120, the first and second supply pipes 54 and 56 and the first and second discharge pipes 58 and 60 are provided with an inclined portion 122 that is inclined upward toward the fuel cell stack 120. Therefore, in the fourth embodiment, the water 72 can be reliably prevented from being introduced into the fuel cell stack 120 through the stepped portion 70 and the inclined portion 122, and the third embodiment can be prevented. The same effect can be obtained.
[0037]
【The invention's effect】
In the fuel cell stack 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 oxidant gas flow path in the fuel cell stack, The fuel cell stack is provided with an enlarged portion having a stepped part protruding downward from the other part of the pipe line in a part of the pipe itself , and water condensed in the pipe line is accumulated in the stepped part. Will not be introduced in. As a result, the fuel cell stack can be stably operated for a long time with a simple configuration.
[0038]
In 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 oxidant gas flow path of the fuel cell stack is provided in the fuel cell stack. An inclined portion that is inclined upward is provided. For this reason, water condensed in the pipe line is not sent into the fuel cell stack and 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 view of a fuel cell stack 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.
FIG. 3 is a partially exploded perspective view of the fuel cell stack.
FIG. 4 is a schematic perspective explanatory view of a fuel cell stack according to a second embodiment of the present invention.
FIG. 5 is an explanatory cross-sectional view of a main part of the fuel cell stack shown in FIG. 4;
FIG. 6 is a partial cross-sectional explanatory view of a fuel cell stack according to a third embodiment of the present invention.
FIG. 7 is a partial cross-sectional explanatory view of a fuel cell stack according to a fourth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 80, 100, 120 ... Fuel cell stack 12 ... Unit fuel cell 14, 16 ... Separator 18 ... Electrolyte membrane 20 ... Anode side electrode 22 ... Cathode side electrode 24, 26 ... Gasket 32, 34, 82 ... End plate 38 ... fuel gas supply channel 40 ... oxidant gas supply channel 42 ... cooling water discharge channel 44 ... fuel gas discharge channel 46 ... oxidant gas discharge channel 48 ... cooling water supply channel 50, 52, 53 ... flow Channels 54, 56, 84, 86 ... Supply piping 58, 60, 88, 90 ... Discharge piping 62 ... Cooling water discharge piping 64 ... Cooling water supply piping 68 ... Enlarged portion 70 ... Stepped portion 92, 122 ... Inclined portion 104a-104d ... Liquid retention parts 106a to 106d ... Water level gauges 108a to 108d ... Drain valve

Claims (3)

While laminating unit fuel cells and separators configured by sandwiching a polymer electrolyte membrane between an anode side electrode and a cathode side electrode alternately in the horizontal direction,
A fuel cell stack provided with a fuel gas flow path for supplying fuel gas to the anode side electrode and an oxidant gas flow path for supplying oxidant gas to the cathode side electrode,
First and second supply pipes provided on an end plate of the fuel cell stack and connected to inlet sides of the fuel gas flow path and the oxidant gas flow path;
First and second exhaust pipes provided on the end plate and connected to outlet sides of the fuel gas flow path and the oxidant gas flow path;
With
At least one of the first supply pipe to which the humidified fuel gas is supplied and the second supply pipe to which the humidified oxidant gas is supplied has an opening diameter of the pipe at a part of the pipe itself. by expanding the diameter of the enlarged portion having a step portion projecting downward than the other portions is provided, the fuel cell stack water condense該配tract characterized Rukoto is discharged to the step portion. While laminating unit fuel cells and separators configured by sandwiching a polymer electrolyte membrane between an anode side electrode and a cathode side electrode alternately in the horizontal direction,
A fuel cell stack provided with a fuel gas flow path for supplying fuel gas to the anode side electrode and an oxidant gas flow path for supplying oxidant gas to the cathode side electrode,
A first supply pipe and a second supply pipe provided on an end plate stacked in the horizontal direction on the fuel cell stack and connected to an inlet side of the fuel gas flow path and the oxidant gas flow path;
First and second exhaust pipes provided on the end plate and connected to outlet sides of the fuel gas flow path and the oxidant gas flow path;
With
At least one of the first supply pipe to which the humidified fuel gas is supplied and the second supply pipe to which the humidified oxidant gas is supplied is inclined upward toward the fuel cell stack. an inclined portion is provided, the fuel cell stack water condensed in the pipes, characterized that you prevented from moving into the fuel cell stack. The fuel cell stack according to claim 1, wherein a liquid reservoir is provided that communicates with at least one of the first supply pipe and the second supply pipe;
In the liquid reservoir, a water level meter that detects the level of water stored in the liquid reservoir,
A discharge valve for discharging water from the liquid reservoir when it is determined by the water level gauge that a predetermined amount or more of water has been stored in the liquid reservoir;
A fuel cell stack.

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