KR101417454B1 - End plate for fuel cell stack - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water discharge and flow distribution device for an end plate for a fuel cell stack of a new structure for discharging fuel cells and improving flow distribution.
To this end, the present invention provides a fuel cell stack including an open-type end plate and a closed-type end plate which are respectively disposed on one side and the other side of the fuel cell stack and fasten a plurality of unit cells made of normal cells, A water discharge passage is formed so that the condensed water flowing on the inlet passage wall of the open end plate as the stack inlet is discharged to the outlet passage of the open end plate as the outlet of the stack and at the same time the heat transmitted from the unit cells as normal cells And a heat release buffer zone for discharging the fuel cell stack.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an end plate for fuel cell stack,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water discharge and flow distribution device for an end plate for a fuel cell stack, and more particularly, to a water discharge and flow distribution device for a fuel cell stack, .

The fuel cell stack is a type of power generation device that produces electricity that is a main energy source of a fuel cell vehicle. The fuel cell stack has a structure in which a fuel electrode to which hydrogen is supplied and an air electrode to which air is supplied are stacked with an electrode film assembly therebetween. It refers to a device that generates electricity by chemically reacting hydrogen supplied from the outside.

Typically, the fuel cell stack is stacked with tens to hundreds of unit cells.

The unit cell configuration of the fuel cell stack includes a polymer electrolyte membrane capable of moving hydrogen cations (protons), a cathode layer and a cathode layer, which are catalyst layers applied to both surfaces of the electrolyte membrane, a gas diffusion layer is stacked on the outer portion of the air electrode and the fuel electrode, and a fuel is supplied to the outside of the gas diffusion layer. And a separation plate on which a flow field is formed to discharge water generated by the reaction.

After several tens to several hundreds of the unit cells are stacked, an end plate for supporting and fixing the respective components is coupled to the outermost sides as schematically shown in FIG. 1, The battery stack is completed.

As shown in FIG. 1, when several unit cells of the fuel cell stack 10 are stacked in the range of several tens to several hundreds, in addition to the normal cells 12 that normally generate electricity, three or more The dummy micelles 14 are stacked.

Particularly, as shown in Fig. 1, one end plate 20 is adopted as a closed type end plate 22 of a closed structure, and the other end plate is used as an inlet passage 26 for introducing hydrogen and air, And an outlet passage 28 for discharging the unreacted gas and the cooling water is formed in the lower portion of the open end plate 24.

Therefore, hydrogen is supplied to the fuel electrode through the inlet passage 26 of the open end plate 24 of the fuel cell stack 10, air (oxygen) is supplied to the air electrode, and cooling water for cooling is also supplied to the open- Passes through the inlet passage (26) of the plate (24) and is supplied to the cooling water channel of the separator plate.

As a result, the oxidation reaction of hydrogen proceeds in the fuel electrode to generate hydrogen ions (protons) and electrons. At this time, the generated hydrogen ions and electrons move to the air electrode through the electrolyte membrane and the separator plate, The hydrogen ion and the oxygen in the air participate in the electrochemical reaction to generate water and generate electric energy from the flow of electrons.

On the other hand, since the fuel (hydrogen / air) supplied to the fuel cell must be supplied with humidified fuel (RH 50% ↑) for maintaining the membrane performance, when the humidified fuel supplied to the stack passes through the supply passage, Condensate is generated due to low temperature.

At this time, the generated condensed water flows into the stack along the fuel wall with the fuel, and the condensed water enters the cell, and the performance and the durability are lowered because the deterioration of the catalyst caused by the continuous presence of water around the catalyst Can be found.

In order to solve this problem, as shown in FIG. 1, at least three more micelles (14: unreacted cells for generating electricity as condensed water discharge passages) are disposed at the stack inlet position adjacent to the open end plate 24 However, there are problems such as cost increase and weight increase due to application of micrometer.

In addition, since fuel and cooling water are supplied on the side of the stack in the stack structure, the flow rate of the flow to each cell of the stack is not evenly distributed, so that the inlet / outlet cell of the stack adjacent to the open- And a phenomenon that a small flow rate is supplied to the cell on the side of the closed side with the closed type end plate on the opposite side.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel cell stack capable of preventing condensate from flowing into each reaction cell of a fuel cell stack and uniformly distributing fuel supplied to the stack to each cell, And an object of the present invention is to provide a water discharge and flow distribution device for an end plate for a fuel cell stack for improving water discharge and flow distribution.

According to an aspect of the present invention, there is provided a fuel cell stack including: an open-type end plate and a closed-type end plate, each of which is disposed on one side and the other side of the fuel cell stack, And the condensed water flowing on the inlet passage wall surface of the open type end plate as the stack inlet is discharged toward the outlet passage of the open type end plate which is the outlet of the stack. And a water discharge and flow distribution device for the end plate.

Preferably, the inlet passage of the open-type end plate is further formed with a stepped portion such that the front open plate of the water discharge passage is lower in height than the rear open plate, so that the inlet passage is wider than the supply passage.

More preferably, a porous structure for preventing at least one of hydrogen and air from leaking out is disposed in the water discharge passage of the open type end plate.

In particular, the porous structure body is placed at a lower position of the water discharge path of the open type end plate, so that a water storage space can be secured above the porous structure body.

Also, the porous structure is characterized in that the gas permeability characteristic value is adopted to have the same value as the gas permeability characteristic value of the unit cell.

Also, the water discharge channel of the open-type end plate is formed of a heat-releasing buffer zone for blocking external discharge of heat transmitted from the unit cells as normal cells.

Preferably, the porous structure body includes a first porous structure attached to the hydrogen flow path of the open end plate, and a second porous structure attached to the air flow path to the water discharge path.

Through the above-mentioned means for solving the problems, the present invention provides the following effects.

According to the present invention, it is possible to form a water discharge flow passage vertically passing through the open end plate of the fuel cell stack to discharge the condensed water flowing into the normal cell to the outside through the water discharge flow passage, It is possible to prevent degradation of performance.

Further, since the fuel (air and / or hydrogen) can be induced to flow to the cell located on the opposite side of the inlet passage by forming a stepped portion in the inlet passage of the open type end plate, the fuel supplied to the stack can be uniformly distributed .

In addition, it is possible to eliminate the existing micelles, thereby reducing the cost and weight, and it is possible to obtain the fuel efficiency improved by feeding the fuel supplied to the existing micelles to the normal cells.

For example, if the amount of fuel passing through the water discharge channel is equal to the amount of fuel supplied to one existing micelle, if the three micromoles are already present, fuel efficiency may be improved as much as the fuel supplied to the two micells have.

In addition, the porous structure may be provided in the water discharge passage of the present invention to easily prevent part of the fuel (air and / or hydrogen) from being discharged out of the stack through the water discharge passage.

In addition, the water discharge channel of the present invention can achieve a function of not only discharging condensed water but also functioning as a thermal buffer zone for preventing heat generated in a normal cell and preventing excessive generation of condensed water in a normal cell .

1 is a schematic cross-sectional view showing a conventional fuel cell stack structure,
FIG. 2 is a cross-sectional view of a water discharge and flow distribution device for an end plate for a fuel cell stack according to the present invention,
3 is a partial cross-sectional view illustrating a fuel (gas) flow induction function of a water discharge and flow distribution device of an end plate for a fuel cell stack according to the present invention,
4 is a partial cross-sectional view illustrating a heat dissipation function for an operating cell of a water discharge and flow distribution device of an end plate for a fuel cell stack according to the present invention,
5 is a graph showing the flow distribution analysis results of the present invention and the conventional technique.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2, a closed type end plate 22 of a closed structure is provided on one side of each unit cell of the fuel cell stack 10, that is, in a state where several tens to several hundreds of normal cells without stacked micelles are stacked, And the other end is connected to the open end plate 24. Although not shown, the closed end plate 22 and the open end plate 24 are separately bent or clamped to provide a fastening surface pressure for the normal cell, It is bound by means.

At this time, an inlet passage 26 for introducing hydrogen, air, cooling water, and the like is formed in the upper end of the open type end plate 24 through the normal cell 12, An outlet passage 28 for discharging the unreacted gas and the cooling water is formed.

2, the supply passage 16 and the discharge passage 18 formed at the top and bottom of the normal cell represent manifold portions of the separator laminated to each other via gaskets, A cooling water supply passage and an exhaust passage.

Therefore, after hydrogen, air, and cooling water pass through the inlet passage 26 of the open end plate 24 of the fuel cell stack 10, hydrogen is supplied to the fuel electrode via the supply passage 16, (Oxygen) is supplied to the air electrode, and cooling water for cooling is also supplied to the cooling water flow path formed on the back surface of the separator plate.

At this time, the fuel (air and / or hydrogen) is supplied in a humidified state in order to maintain membrane performance. When the humidified fuel passes between the BOP and the stack, condensation water is generated due to the low ambient temperature If the condensed water flows into the normal cell, the performance and durability due to the deterioration of the catalyst will occur.

In order to solve this problem, the present invention is characterized in that the present invention is characterized in that a water discharge passage 30 penetrating through the upper and lower open end plates 24 is formed separately from the conventional method of using micelles, The flow path 30 communicates between the inlet passage 26 and the outlet passage 28 of the open type end plate 24.

Of course, although the inlet passage 26 and the outlet passage 28 of the open-ended end plate 24 are not shown, since the inlet passage and the outlet passage for hydrogen and the inlet passage and the outlet passage for air are separately formed, The water discharge passage 30 is also formed between the inlet passage and the outlet passage for hydrogen, and between the inlet passage and the outlet passage for air, respectively.

Accordingly, even if condensed water is generated due to the low ambient temperature when the humidified fuel passes through the front and rear flow passages of the inlet passage 26 of the open end plate 24, the condensed water generated at this time passes through the open end plate 24, And can be easily discharged and removed to the outside of the stack through the outlet passage 28 formed in the lower portion of the open type end plate 24. As the condensate water is easily removed, Can be prevented from being introduced into the normal cells and deteriorating performance and durability due to catalyst deterioration.

As a preferred embodiment of the present invention, the water discharge passage 30 passing through the open-type end plate 24 is not only capable of discharging condensed water, but also functioning as a heat-releasing buffer zone.

That is, when the normal cell 12 of the fuel cell stack reacts to generate electricity, heat is generated. When the heat is discharged to the outside, the supercooling degree of the normal cell 12 causes excessive condensation even in the normal cell The heat generated in the normal cell 12 is blocked by the water discharge passage 30, that is, the heat release buffer zone, as shown in FIG. 4, thereby preventing excessive generation of condensate in the normal cell. Effect can be obtained.

As another preferred embodiment of the present invention, a stepped portion 32 communicating with the water discharge passage 30 in the horizontal direction is further formed in the bottom entry portion of the inlet passage 26 of the open type end plate 24. [

More specifically, the stepped portion 32 is formed such that the inlet passage 26 of the open end plate 24 becomes narrower toward the inside. By forming the stepped portion 32, And the inlet passage 26 is formed to be wider than the side of the supply passage 16, because the front open plate 24 of the first opening plate 24 is lower in height than the rear open plate 24.

3 and 5, the fuel (air and / or hydrogen) flowing through the inlet passage 26 of the open-type end plate is in contact with the stepped portion 32, So that it can be guided upward and supplied to the supply passage 16 of the normal cell.

That is, the fuel (air and / or hydrogen) flowing through the inlet passage 26 can be prevented from reaching the stepped portion 32 and moving toward the adjacent normal cells of the stack inlet, The fuel supplied to the cell can be induced to flow from the inlet to the farthest inner normal cell, so that the fuel supplied to the stack can be uniformly distributed to each cell.

As another preferred embodiment of the present invention, a porous structure body 34 is provided at an arbitrary position in the water discharge passage 30 of the open-type end plate 24 to prevent hydrogen or air from leaking to the outside. have.

Of course, the porous structure 34 includes a first porous structure mounted in a water discharge passage 30 formed between the inlet passage and the outlet passage for hydrogen, and a water discharge passage (not shown) formed between the inlet passage and the outlet passage for air 30). ≪ / RTI >

The porous structure body 34 installed in the water discharge passage 30 is formed so that a part of the fuel (air and / or hydrogen) flowing through the inlet passage 26 of the open type end plate passes through the water discharge passage 30 And functions to shut off the discharge to the outside of the stack.

That is, the porous structure body 34 acts as a gas flow resistance against the fuel (air or hydrogen) to be discharged to the outside through the water discharge passage 30, thereby preventing excessive fuel leakage through the water discharge passage 30 .

The porous structure body 34 may be disposed at a lower portion of the water discharge passage 30 to prevent the fuel from being excessively discharged even if the porous structure body 34 is installed anywhere in the water discharge passage 30. However, 34, it is desirable that the accumulated water plays a role of preventing the fuel outflow, and of course, the accumulated water is gradually discharged through the porous structure 34 to the outside.

At this time, the porous structure 34 can be applied regardless of any material and structure, but the fuel permeability can be prevented only if the gas permeability characteristic value has the same value as the gas permeability characteristic value of the unit cell.

10: Fuel cell stack
12: Normal cell
14: The micelle
16:
18:
20: End plate
22: Closed type end plate
24: Open type end plate
26: entrance passage
28: outlet passage
30: Water discharge channel
32:
34: porous structure

Claims (7)

delete And an open type end plate (24) and a closed type end plate (22), each of which is disposed on one side and the other side of the fuel cell stack (10) to fasten a plurality of unit cells of a normal cell,
A water discharge passage 30 penetrating through the open end plate 24 is formed so that the condensed water flowing on the wall surface of the inlet passage 26 of the open end plate 24, To exit to the outlet passage 28 of the plate 24,
The inlet passageway 26 of the open end plate 24 is formed with a stepped portion 26 so that the front open plate of the water discharge passage 30 is lower in height than the rear open plate 26 so that the inlet passage 26 is wider than the supply passage 16 side. (32) is further formed on the end plate (20).
And an open type end plate (24) and a closed type end plate (22), each of which is disposed on one side and the other side of the fuel cell stack (10) to fasten a plurality of unit cells of a normal cell,
A water discharge passage 30 penetrating through the open end plate 24 is formed so that the condensed water flowing on the wall surface of the inlet passage 26 of the open end plate 24, To exit to the outlet passage 28 of the plate 24,
Wherein a porous structure (34) is provided in the water discharge passage (30) of the open type end plate (24) for preventing excessive flow of at least one of hydrogen and air. Flow distribution device.
The method of claim 3,
The porous structure body (34) is placed at a lower position of the water discharge flow passage (30) of the open type end plate (24) so that a water storage space can be secured above the porous structure body (34) Discharge and flow distributing device for stack end plates.
The method of claim 3,
Wherein the porous structure (34) is adapted to have a gas permeability characteristic value equal to a gas permeability characteristic value of the unit cell.
The method according to claim 2 or 3,
Wherein the water discharge passage (30) of the open-type end plate (24) is formed of a heat release buffer zone which blocks external discharge of heat transmitted from the unit cells constituting the normal cell (12) Water discharge and flow distribution device.
The method of claim 3,
The porous structure body 34 includes a first porous structure body mounted in the hydrogen flow path water discharge passage 30 of the open type end plate 24 and a second porous structure body mounted in the air flow path water discharge flow passage 30 And the water discharge and flow distribution device of the end plate for fuel cell stack.

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