KR20110059029A - Separater for fuel cell stack - Google Patents

Abstract

PURPOSE: A separator for a fuel cell stack is provided to prevent the condensation of water inside air and hydrogen manifolds and the corrosion of the manifold by forming an inclined angle so that water condensed in the floor of an air and hydrogen inlet manifold flows in a reaction path of the separator. CONSTITUTION: A separator(20) for a fuel cell stack includes manifolds that provide a path of air, cooling water, and hydrogen at both ends thereof. A slope zone for removing condensed water is formed in an air inlet manifold(22) flowing in air and hydrogen and a hydrogen inlet manifold(32). Since an inclined angle is formed in only the air inlet manifold and hydrogen inlet manifold toward reaction flow channels(50) so that the condensed water flows into a reaction flow path.

Description

Separator for fuel cell stack {Separater for fuel cell stack}

The present invention relates to a separator for a fuel cell stack, and more particularly, to newly improve the structure of a fluid supply manifold formed in a separator for a fuel cell to prevent corrosion caused by water condensed in the manifold. A separator for a fuel cell stack is provided.

Referring to FIG. 6 attached to the configuration of the fuel cell stack, a cathode (12: cathode) and a cathode (14), which is a polymer electrolyte membrane 10 and a catalyst layer coated to react hydrogen and oxygen on both surfaces of the electrolyte membrane, are described. A membrane-membrane-electrode assembly (MEA) comprising an anode, and a gas diffusion layer (GDL) 16 and a gasket 18 located at an outer portion where the cathode 12 and the anode 14 are located. ) Are sequentially stacked, and a separator 20 having a flow field is provided at the outside of the gas diffusion layer 16 to supply fuel and discharge water generated by the reaction. End plates 30 are fixed for fixing them.

Accordingly, the oxidation reaction of hydrogen proceeds in the anode 14 of the fuel cell stack to generate hydrogen ions (Proton) and electrons (Electron), and the generated hydrogen ions and electrons are separated from the electrolyte membrane 10, respectively. The electrode 20 moves to the cathode 12 through the plate 20. At the cathode 12, water is generated through an electrochemical reaction involving hydrogen ions, electrons, and oxygen in the air. Electric energy is generated from the flow of electrons.

Looking at the structure of the separator with reference to the accompanying Figure 2 as follows.

The separation plate 20 generally has a rectangular shape, and both ends thereof have inlets and outlet manifolds for entering and exiting three kinds of fluids, such as air and hydrogen, and cooling water, which are reactive fluids. In the region between the manifolds, the land plate closely adhered to the gas diffusion layer of the electrode membrane assembly, and the channel plate forming the reaction flow path and the cooling water flow path through which the reactor body flows are manufactured.

The manifold of the general metal separator plate has a rectangular shape when the separator plate has a rectangular shape. As shown in FIG. 2, the air and hydrogen inlet manifolds 22 and 32 and the air and hydrogen outlet manifold are shown. The folds 24 and 34 are designed to be positioned diagonally to each other so that the product water is discharged in the downward direction by the effect of gravity.

The air and hydrogen inlet manifolds 22 and 32 of the separator 20 have a passage through which air and hydrogen, which are humidified reactor bodies, are supplied from an external source of the stack so that the electrode membrane assembly including the electrolyte membrane can operate smoothly. The air and hydrogen outlet manifolds 24 and 34 become the passages through which the gaseous or liquid state of the humidified and supplied reactant and the water generated inside the cell is discharged to the outside of the stack.

At this time, when the reaction body, that is, the reaction gas is air, water generated in the cathode is added, and the water generated in the cathode passes through the electrolyte membrane and passes to the fuel electrode.

In particular, when the temperature of the reactor gas supplied from the outside of the stack and the internal temperature of the stack are different from each other, a humidified gas may condense and accumulate inside the air and hydrogen inlet manifolds.

Since the fuel cell stacks are closely arranged at very narrow intervals, each cell including the separator plate has a problem that, when each separator plate is stacked, water condensed and accumulated in the manifold of the separator plate is accumulated over several cells. Occurs.

In such a situation, when each cell of the fuel cell stack is exposed to high potentials (eg, open circuit voltage), a potential difference of several V may be formed by water accumulated over several cells. In addition, the manifold of the metal separator may be exposed to an extreme electrocorrosive atmosphere, and the corrosion progresses over time with the deterioration of the electrode membrane assembly (MEA) due to the introduction of metal ions into each cell. The manifold portion may be cut off.

In particular, as shown in positions A and B shown in FIG. 2, condensate may accumulate in the lower ends of the air inlet and hydrogen inlet manifolds 22 and 32 to cause oxidation, which is illustrated in FIG. 3. As described above, water is accumulated in the bottoms 23 and 33 of the one-cell manifolds 22 and 32 with the gasket 18 interposed therebetween, or one set of the manifolds 22 and 32. There is a problem that is less than 1V in the state where water is accumulated on the bottom and it is difficult to completely remove it.

Therefore, a high potential of more than 1 V and a few V may be formed over several cells, and a metal material used as a metal separator may cause a very high potential difference corrosion, and indeed, a condition in which the potential difference corrosion occurs may occur in the stack. When formed, even if only a few tens of hours of stack operation time, corrosion of the manifold is severely generated in a shape in which the bottom of the manifold is water.

In order to solve this problem, in the prior art, the manifold part is made of a non-conductive material, or, in the case of a metal separator, the coating material of the manifold part and the reaction surface part is different so that the coating resistance of the manifold part is enhanced or the non-conductive coating is applied. In some cases, this causes the manufacturing process of the metal separator plate to be partially different, resulting in a complicated manufacturing process and an increase in manufacturing cost.

Also. When the manifold part of the separator is coated with the same material as the polymer, it is difficult to precisely control the coating thickness, and when the surface height step with the reaction surface occurs, and when stacking hundreds of cells, the length and the surface pressure are different for each stack position. Can lead to structural instability and performance nonuniformity of the stack.

The present invention has been made to solve the above problems, the water condensed in the bottom of the air and hydrogen inlet manifold of the fluid supply manifold formed in the fuel cell separator flows into the reaction flow path of the separator plate It is an object of the present invention to provide a separator plate for a fuel cell stack that can prevent the condensation of water in the air and hydrogen manifolds while providing a possible inclination angle.

In order to achieve the above object, the present invention provides a metal separator of a fuel cell stack in which a manifold serving as a passage for air, cooling water, and hydrogen is formed at both ends, respectively, wherein the air inlet manifold and hydrogen are introduced. Provided is a separator for a fuel cell stack, characterized by forming an inclined section for removing condensate in an inlet manifold.

In a preferred embodiment, the bottom of the air inlet manifold and the hydrogen inlet manifold has an inclined angle that is inclined downward toward the reaction flow passage, so that condensed water can flow toward the reaction flow passage and be removed.

In a more preferred embodiment, the inclination angle with respect to the bottom of the air inlet manifold and hydrogen inlet manifold is characterized in that it is formed by adjusting the range of 0 ° or more and 90 ° or less to overcome the surface tension of the condensate.

Through the above problem solving means, the present invention provides the following effects.

According to the present invention, water is condensed in the air and hydrogen inlet manifolds by giving a predetermined downward inclination angle to the reaction flow path to the bottom of the air and hydrogen inlet manifolds of the fluid supply manifold formed in the separator for fuel cell. It can be easily flowed to the side, and at the same time, it is possible to easily prevent corrosion of the manifold due to the removal of condensate.

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

First, the manifold structure of the existing separator and the condensate generation process according to the present invention will be described with reference to the accompanying FIGS. 4 and 5 to help understand the present invention.

In FIG. 4, reference numeral 100 denotes an electrode membrane assembly (MEA) consisting of a cathode and an anode, which are a polymer electrolyte membrane and a catalyst layer applied to react hydrogen and oxygen on both surfaces of the electrolyte membrane.

In the outer portion of the electrode membrane assembly, a gas diffusion layer (GDL) is interposed therebetween, and separator plates having a gasket are sequentially stacked to form one cell.

In addition, an air inlet manifold 22, a coolant inlet manifold 42, and a hydrogen outlet manifold 34 are formed at one end of the separation plate 20 and are arranged in a downward direction from above. Hydrogen inlet manifold 32, cooling water outlet manifold 44, and air outlet manifold 24 are formed at the other end of the end and arranged in a downward direction from the top, and at the center thereof, a channel plate and The reaction flow path 50 made of a lens plate is formed in a predetermined arrangement.

Thus, as indicated by A in FIG. 5A, the outer portion of the bottom body 23 of the air inlet manifold 22 (the corner far from the inlet and the entrance to the reaction flow path in the bottom section of the air inlet manifold), and FIG. 5B. As indicated by B, condensate is likely to accumulate in the outer portion of the bottom body 33 of the hydrogen inlet manifold 32 (the inlet and the far corner of the bottom of the hydrogen inlet manifold into the reaction flow path). This can lead to corrosion of the manifold.

That is, in the air and hydrogen inlet manifolds 22 and 32, the reactant flows into the reaction flow path 50 and is sucked in, but the flow of the reactant is relatively at the positions A and B shown in FIGS. 5A and 5B. Since the stagnant condensed water is forced to remove and remove the condensed water toward the reaction flow path, condensate continues to exist on the bottoms 23 and 33 of the air and hydrogen inlet manifolds 22 and 32, causing corrosion. .

On the other hand, in the air and hydrogen outlet manifolds 24 and 34, the flow of the reactant after the reaction from the reaction passage 50 hits the opposite side wall (outer wall) of the manifold, which causes The water present can be flowed and discharged to the outside by the discharge pressure of the reactor.

In order to easily remove the condensate present in the air and hydrogen inlet manifolds (22, 32), the air and hydrogen inlet manifold so that the condensate flows naturally into the reaction flow path (50) by the flow pressure and gravity of the reactor body It is characteristic in that the structure of the folds 22 and 32 is improved.

That is, as shown in FIG. 1 attached so that the condensed water naturally flows toward the reaction flow passage 50, the bottom body 23 of the air and hydrogen inlet manifolds 22 and 32 of the separator 20 according to the present invention. 33) is characterized by the inclination angle.

More specifically, as indicated by D in FIG. 1, the bottom body 23 of the air inlet manifold 22 and the bottom body 33 of the hydrogen inlet manifold 32 are arranged in the center of the separation plate 20. It is formed to be inclined toward the reaction flow path 50, but by being formed at an inclination angle in the range of 0 ° or more and 90 ° or less, the condensate generated in the air and hydrogen inlet manifolds (22, 32) reacts by the flow pressure and gravity of the reactor body The condensate can be easily removed by allowing the flow path 50 to flow naturally.

Generally, water droplets on a metal surface tend to stick together due to their surface tension and not move on the surface, but by giving the bottom of the air and hydrogen inlet manifolds an angle of inclination to overcome surface tension. Depending on the driving conditions of the vehicle (acceleration, deceleration, forward, reverse, rotation, road impact, etc.), the condensed water can be sufficiently flowed down the reaction flow path and removed.

At this time, if the same concept of inclined structure is applied to the air and hydrogen outlet manifolds 24 and 34, water tends to flow toward the reaction flow path, which may adversely affect the discharge of generated water and reduce the inclination in the opposite direction. In this case, an acute angle groove is formed at the manifold edge, which makes it difficult for the stagnant water to flow out, and a dead space is formed at the bottom of the separator plate, which increases the volume of the stack. It is preferable to apply the inclined structure only to the bottom of the.

On the other hand, the positioning hole 52 of the separation plate 20 according to the present invention, that is, the position of the hole for the coupling between the separation plate is formed in the outside of the separation plate out of the manifold, thereby increasing the inlet and outlet area of the cooling water manifold It can be expanded, thereby reducing the coolant differential pressure can provide an advantage that the fuel cell operating conditions can be stably maintained.

1 is a plan view showing a separator for a fuel cell stack according to the present invention;

2 is a plan view showing a conventional separator for a fuel cell stack and a photograph illustrating oxidation by condensate;

3 is a cross-sectional view illustrating a phenomenon in which condensate accumulates in a conventional separator for fuel cell stacks;

4 and 5 are a perspective view and a main part plan view illustrating a conventional separator and a fluid flow direction for a fuel cell stack;

6 is a schematic view for explaining the configuration of a fuel cell stack;

<Explanation of symbols for the main parts of the drawings>

10: electrolyte membrane 12: air electrode

14 fuel electrode 16 gas diffusion layer

18: Gasket 20: Separator

22: air inlet manifold 23: bottom body

24: Air outlet manifold 30: End plate

32: hydrogen inlet manifold 33: bottom body

34: Hydrogen Outlet Manifold 42: Coolant Inlet Manifold

44: coolant outlet manifold 50: reaction flow path

52: positioning hole

Claims (3)

In the metal separation plate of the fuel cell stack formed with a manifold which is a passage for air, cooling water and hydrogen at both ends, Separating plate for the fuel cell stack, characterized in that by forming an inclined section for removing condensate in the air inlet manifold and hydrogen inlet manifold to which air and hydrogen are introduced. The method according to claim 1, Separating plate for a fuel cell stack, characterized in that only the bottom of the air inlet manifold and the hydrogen inlet manifold has an inclination angle inclined downward toward the reaction flow path, so that condensate flows to the reaction flow path to be removed. The method according to claim 2, The inclination angle with respect to the bottom of the air inlet manifold and hydrogen inlet manifold is formed by adjusting the range of 0 ° or more and 90 ° or less to overcome the surface tension of the condensate.

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