KR101406520B1 - Fuel cell stack - Google Patents

Abstract

The fuel cell stack according to an embodiment of the present invention includes a separator plate having an opening through which a fluid flows and a unit cell provided between the separator plates to form a laminate, The width of the separating plate may be varied.

Description

A fuel cell stack {Fuel cell stack}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell stack, and more particularly, to an invention for improving the performance of a fuel cell stack by smoothly supplying a fluid to a unit cell by modifying a structure of an opening formed in a separating plate.

Fuel cells are considered to be the most efficient energy conversion device for producing electricity using hydrogen and will be the core technology of future hydrogen society. At present, the use of fossil fuels as energy sources and energy storage media, fuel cell as a highly efficient and environmentally friendly energy conversion device has various applications, and researches for commercialization in various countries around the world for energy saving and other special purposes It is actively underway.

Such a fuel cell is an energy conversion device that converts chemical energy generated by oxidation and reduction of a reactant into electric energy. Generally, a fuel cell is composed of an anode and an cathode, and an electrolyte matrix or a membrane disposed between the anode and the cathode. In this fuel cell, fuel gas is injected into a fuel electrode to be oxidized, air is supplied to the air electrode, ions are moved through an electrolyte matrix or a membrane located between the fuel electrode and the air electrode, and electrons are operated in such a manner as to pass through the external circuit.

In other words, electrons generated in the anode are transferred to the cathode and consumed, and electrons flow to the external circuit, and the electric energy is produced using the electrons. Therefore, the chemical reaction in the fuel cell is the same as the reaction in which hydrogen and oxygen meet and become water.

On the other hand, a fuel cell composed of an air electrode, a fuel electrode, and an electrolyte membrane such as an electrolyte matrix or a membrane is referred to as a unit cell. Since the amount of electric energy produced by one unit cell is very limited, It is inevitable to form a stack structure, which is a stacked form.

In this manner, the stack structure is formed by positioning the separator plate between the unit cells. The separator plate electrically connects each unit cell to collect electricity generated in the unit cell.

On the other hand, an opening passing through the stack may be formed to supply a fluid such as fuel or air to the unit cells.

However, if a large number of unit cells are stacked, the supply may be uneven depending on the direction in which the fluid is supplied. That is, if the fuel is supplied in the vertical direction, the supply of the horizontal fuel, which is a direction of supplying the unit cells, is not performed due to the inertial force of the fuel in the vertical direction.

In addition, such unevenness of the fuel supply causes deterioration of the performance of the unit cell, and particularly, this phenomenon is serious in the unit cell on the fluid inlet side. For example, if the fuel is supplied to a lower portion of a vertical flow manifold formed by a plurality of openings, the fuel supply to the unit cells located mainly below the plurality of unit cells is not smooth, There is a problem of deteriorating.

Therefore, it is necessary to study a new fuel cell stack for solving the imbalance of the fuel supplied to each stacked unit cell.

It is an object of the present invention to provide a fuel cell stack in which performance is improved by modifying the structure of openings provided in the fuel cell so as to supply fuel to each unit cell in a balanced manner.

The fuel cell stack according to an embodiment of the present invention includes a separator plate having an opening through which a fluid flows and a unit cell provided between the separator plates to form a laminate, The width of the separating plate may be varied.

Further, the openings of the fuel cell stack according to an embodiment of the present invention may be provided to the separator plates of the respective layers by decreasing the width sequentially from the openings formed in the separator plate on the fluid inlet side.

Further, the opening of the fuel cell stack according to an embodiment of the present invention may be deformed at the other side of the inner surface in the direction of the unit cell so that one side of the inner surface thereof is positioned on the same line perpendicular to the separator plate.

In addition, the opening of the fuel cell stack according to an embodiment of the present invention may change the width only in a part of the laminated plate.

Further, the opening of the fuel cell stack according to an embodiment of the present invention may be formed by decreasing the width sequentially only in a part of the separation plates stacked adjacent to the fluid inflow side.

Further, the openings of the fuel cell stack according to an embodiment of the present invention may be formed on both sides of the separator plate, and the openings formed on both sides of the separator plate may have asymmetrical widths.

The fuel cell stack according to the present invention has the effect of generating turbulence in the fluid supplied to the unit cells by forming the width of the openings provided in the stacked separator plates differently in each layer.

Accordingly, the fluid can be introduced into the unit cell, and an advantage that the fluid can be uniformly distributed can be obtained.

Therefore, the performance of the fuel cell as a whole can be improved, and the effect of producing more electricity at the same time can be expected. This also has the advantage of helping to secure price competitiveness of the fuel cell.

Further, all of the stacked unit cells can be operated in a uniform state, and the uniformity of the temperature of each unit cell can be ensured. Thereby, there is an advantage that it is possible to prevent the specific portion from being overheated even in the long-term operation of the fuel cell.

1 is a cross-sectional view schematically showing a conventional fuel cell stack and a graph showing a voltage according to a position of a unit cell.
2 is a plan view schematically showing a fuel cell stack according to an embodiment of the present invention.
3 is a cross-sectional view schematically showing a fuel cell stack according to an embodiment of the present invention.
4 is a cross-sectional view schematically illustrating various embodiments of a shape formed by stacking openings of a fuel cell stack according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventive concept. Other embodiments falling within the scope of the inventive concept may readily be suggested, but are also considered to be within the scope of the present invention.

The same reference numerals are used to designate the same components in the same reference numerals in the drawings of the embodiments.

FIG. 1 is a cross-sectional view schematically showing a conventional fuel cell stack and a graph showing a voltage according to the position of the unit cell 10, and FIG. 2 is a plan view schematically showing a fuel cell stack according to an embodiment of the present invention. And FIG. 3 is a cross-sectional view schematically showing a fuel cell stack according to an embodiment of the present invention.

1 to 3, a fuel cell stack according to an embodiment of the present invention is provided between a separator plate 20 having an opening 30 through which a fluid flows in and a separator plate 20 to form a laminate And the opening 30 may be formed by deforming the width 31 of each of the separator plates 20 provided on both sides of the unit cell 10.

The opening 30 of the fuel cell stack according to an embodiment of the present invention may reduce the width 31 sequentially from the opening 30 formed in the separator plate 20 of the fluid inflow side 32 And can be provided to the separation plate 20 of each layer.

The opening 30 of the fuel cell stack according to an embodiment of the present invention may have a width 31 such that one side of the inner surface 33 is located on the same line L perpendicular to the separator plate 20 Can be deformed at the other side of the inner surface (33) of the unit cell (10) in the direction (i).

The fuel cell stack of the present invention relates to an invention for modifying the structure of the opening 30 formed in the separator plate 20 to facilitate fluid supply to the unit cell 10. [

That is, the fuel cell stack of the present invention is formed by forming the widths 31 of the openings 30 provided in the stacked separator plates 20 differently in the respective layers, And the like.

Accordingly, the inertia of the fluid to be advanced is changed in the direction of the unit cell 10, so that the fluid can be guided to the unit cell 10. Thus creating the advantage of allowing uniform distribution of the fluid.

Further, by uniformly distributing the fluid, the performance of the entire fuel cell can be improved, and more electricity can be produced at the same time.

On the other hand, all the stacked unit cells 10 can be operated in a uniform state, and uniformity of the temperature of each unit cell 10 can be ensured. As a result, it is possible to anticipate the advantage of preventing a specific portion from being overheated even during long-term operation of the fuel cell.

The unit cell 10 is formed by an assembly of an electrolyte membrane having oxygen ion conductivity, an air electrode as a cathode located on both sides thereof, and an anode electrode as an anode. That is, in the unit cell 10, fuel gas is injected into the fuel electrode to be oxidized, air is supplied to the air electrode, ions move through the electrolyte membrane to form moisture, and electrons flow to the external circuit in this process Electric energy can be produced.

The separator plate 20 serves to supply fuel or air to the unit cell 10. That is, the separator plate 20 is provided with a passage through which fuel or air can flow, and distributes the fuel or air introduced from the outside through the passage, and a lip separating the passage may be formed between the passages .

In addition, the separator 20 may collect electrons generated in the unit cell 10 and transfer the electrons to the outside. For this purpose, the separator plate 20 may be formed using an electrically conductive material. That is, the split flap 20 may be made of an electrically conductive ceramic material or a metal such as ferritic stainless steel or Fe-Ni alloy.

The separation plate 20 may further include a sealing material 21 to prevent fluid such as fuel or air from being supplied to the unit cell 10 from flowing out.

For this purpose, the sealing material 21 may have a shape that can be coupled to the outside of the rim of the unit cell 10. That is, a continuous band shape can be formed outside the rim of the unit cell 10.

In addition, the sealing material 21 is preferably formed of an elastically restorable material for sealing the fluid. For example, it may be formed of a rubber material or an elastically recoverable metal material.

The separation plate 20 may be provided with an opening 30 to supply a fluid such as fuel or air to the unit cell 10. The fluid flows into and out of the flow path of the separation plate 20 through the opening 30. The fuel flows into and flows out of the flow path of the separation plate 20 contacting the fuel electrode and flows toward the flow path of the separation plate 20 in contact with the air electrode Air flows in and out. A detailed description of the opening 30 will be described later.

The opening 30 is formed in the separator plate 20 and provides a fluid such as fuel or air to the unit cell 10 through the separator plate 20.

Conventionally, the conventional openings 30 'formed on the conventional separator plate 20' are formed to have the same width, so that the fluid provided through the conventional openings 30 'flows into the conventional openings 30' There has been a problem that the fluid is not easily flowed into the conventional separator plate 20 'on the fluid inlet side, which is stacked by the inertial force that advances in the direction of flow.

That is, in order to introduce the fluid into all the stacked conventional unit cells 10 ', a strong oil input must be provided at the beginning of the flow of the fluid. In the conventional unit cell 10' stacked adjacent to the fluid inlet side, There is a problem in that the inertia force by the oil input is the largest and the inflow of the fluid into the conventional unit cell 10 'on the fluid inflow side perpendicular to the inflow direction of the fluid is difficult.

Such a problem can be easily seen from the graph shown in FIG. 1 (b). That is, the graph shown in FIG. 1 (b) is a graph showing the relationship of cell voltages generated according to the cell number, which is the position of the stacked conventional unit cell 10 ' It can be seen that the cell voltage is significantly smaller in the laminated unit cell 10 'having the cell number 70 or more than the unit cell 10' stacked in the other part.

On the other hand, it can be seen that this problem is irrespective of the utilization factor (uf). That is, it can be seen that there is a problem that the cell voltage is low in the laminated unit cell 10 'having the cell number 70 or more even when the fuel utilization rate uf is 25% or 12.5%.

This is caused by the fact that a fluid such as fuel or air is not properly introduced into the conventional unit cell 10 'stacked adjacent to the fluid inflow side, and this problem can be solved in the fuel cell stack of the present invention.

That is, in the fuel cell stack of the present invention, the opening 30 is formed so as to generate turbulence so that the fluid can be changed in the flow direction toward the unit cell 10 while reducing the inertia to be advanced in the initial inflow direction. Which is a change in the structure of.

Specifically, the openings 30 having different widths 31 are formed in each of the separator plates 20 stacked on each layer so that the fluid can easily flow into the unit cells 10.

This is because the manifolds formed by the plurality of the openings 30 provided in the plurality of stacked separator plates 20 are provided in the shape of an oblique tube not in a straight line perpendicular to the separator plate 20 .

When the openings 30 having different widths 31 are formed on all or a part of the separating plates 20 stacked in this manner, the fluid flows into the openings 30, The width 31 formed in the opening 20 collides with one side of the different opening 30 to form the impinging flow f1 which is the fluid flow f flowing in the direction perpendicular to the initial flow direction.

On the other hand, a viscous flow f2, which is a fluid flow f flowing in a direction perpendicular to the initial flow direction, can be formed at one side of the opening 30 by viscosity.

By forming the fluid flow in a direction different from the initial flow direction, the fluid can flow more easily in the direction of the stacked unit cells 10.

The shape of the opening 30 is gradually reduced from the opening 30 formed in the separation plate 20 of the fluid inflow side 32 to the separation plate 20 of each layer .

The opening 30 is formed such that a width 31 of the opening 30 is formed so that one side of the inner surface 33 of the opening 30 is positioned in the same line L perpendicular to the separating plate 20 And the other side of the inner surface 33 of the opening 30 may be formed by deforming the width 31 between the stacked openings 30 differently.

That is, the shape of the flow tube formed by the plurality of openings 30 provided in the plurality of stacked separator plates 20 is a straight line L perpendicular to the separator plate 20, To deform the width (31) of the opening (30).

The collision flow f1 is generated only at the other side of the inner surface 33 of the opening 30 which is introduced into the unit cell 10 so that the collision flow f1 is unnecessarily generated at the inner surface 33 of the opening 30, The flow f1 can be prevented from occurring.

A straight line L perpendicular to the separator plate 20 is formed on an outer side of the unit cell 10 and a straight line inclined to the separator plate 20 is formed on the unit cell 10, (Inner: i).

According to this, in the inner direction (inner: i) of the unit cell 10, the flow of the fluid into the unit cell 10 is facilitated by the impinging flow f1 described above, The inertial force with respect to the initial inflow direction can be maintained and the fluid can be supplied to the unit cell 10 farthest from the fluid inflow side 32. [

The plane shape of the opening 30 may be circular or rectangular. Particularly, in order to guide the fluid toward the unit cell 10, a planar shape of the opening 30 is formed in a tapered shape in the inner direction i of the separator plate 20 or the unit cell 10 .

4 is a cross-sectional view schematically illustrating various embodiments of a shape formed by stacking openings 30 of a fuel cell stack according to an embodiment of the present invention.

Referring to FIG. 4, the opening 30 of the fuel cell stack according to an embodiment of the present invention may deform the width 31 only in a part of the stacked partition plate 20.

That is, the amount of fluid such as fuel or air flowing into the unit cell 10 is insufficient to deform and provide only the width 31 of the opening 30 formed at a low cell voltage portion to increase the inflow amount of the fluid .

As described above, in the portion where the width 31 of the opening 30 is provided differently, the impinging flow f1 is generated a lot and the inflow of the fluid into the adjacent unit cell 10 can be increased.

Accordingly, the cell voltage is increased according to the increase of the inflow of the fluid, so that the performance of the entire fuel cell stack can be improved.

It is also possible to divide the stacked separators 20 into a predetermined group so that the openings 30 in the same group are formed to have the same width 31 and the openings 30 in the other group are formed to have different widths 31 It is possible.

That is, a part of the shape of the flow pipe formed by the plurality of openings 30 provided in the plurality of stacked separator plates 20 can be formed stepwise.

The opening 30 of the fuel cell stack according to an embodiment of the present invention may be formed by sequentially decreasing the width 31 only in a part of the separation plate 20 stacked adjacent to the fluid inflow side 32 can do.

That is, the shape of the flow tube formed by the plurality of the openings 30 provided in the plurality of stacked separator plates 20 is reduced in the width 31 sequentially in only the portion adjacent to the fluid inflow side 32, So that it can be formed into a shape.

This is because the width 30 is formed in the portion that generates a relatively uniform cell voltage in the conventional manner so that the opening 30 is formed such that the shape of the flow tube is linear, 32).

For example, in FIG. 1 (b), cell numbers 1 to 69 where uniform cell voltages are generated do not deform the width 31 of the openings 30, but cell numbers 70 to 110 The width 31 of the opening 30 is deformed to allow the fluid to flow more in the direction of the unit cell 10 to generate the impinging flow f1.

The openings 30 of the fuel cell stack according to the embodiment of the present invention are formed on both sides of the separator plate 20 and the openings 30 formed on both sides of the separator plate 20 are asymmetric The width 31 can be formed.

That is, the amount of fluid flowing into both sides of the unit cell 10 is not increased equally, but the amount of the fluid flowing from both sides of the unit cell 10 depends on the type, To increase the amount.

For this, the deformation amount of the width 31 of the opening 30 may be set differently in each of the openings 30 provided on both sides of the separator plate 20.

10: unit cell 20: separator plate
21: sealing material 30: opening
31: width 32: fluid inflow side
33: Inner surface

Claims (6)

A separation plate having an opening through which the fluid flows; And
A unit cell provided between the separation plates to form a laminate;
/ RTI >
The opening
One side of the inner surface provided in the outer direction of the unit cell is formed to be positioned on the same line perpendicular to the separator plate,
Wherein the other side of the inner surface provided in the inner direction of the unit cell is sequentially deformed so that the opening is provided in the separating plate of each layer by decreasing the width sequentially from the opening formed in the separating plate on the fluid inflow side. delete delete The method according to claim 1,
Wherein the openings are formed by deforming a width of only a part of the separation plates stacked. 5. The method of claim 4,
Wherein the opening portion is formed by sequentially decreasing the width only in a part of the separation plates stacked adjacent to the fluid inflow side. The method according to claim 1,
Wherein the openings are formed on both sides of the separator plate, and the openings formed on both sides of the separator plate have a width asymmetrically with respect to each other.

Images