KR101446195B1 - Equipment for removing carbon dioxide for direct methanol fuel cell - Google Patents

Abstract

A carbon dioxide removing apparatus for a direct methanol fuel cell is disclosed. The disclosed direct methanol fuel cell carbon dioxide removing device comprises a body having a hollow body, at least a part of which is open on at least one side, at least a part of the other side is opened, all sides are closed, and a plurality of through holes are formed in an outer circumferential surface to communicate with the hollow, A gas-liquid separation membrane disposed on the outer circumferential surface of the body so as to cover the plurality of through-holes, and a mesh disposed on the gas-liquid separation membrane.

Accordingly, the disclosed direct methanol fuel cell carbon dioxide removing device can effectively discharge carbon dioxide generated during the oxidation reaction of the fuel cell irrespective of the direction in which the fuel cell is placed.

Description

[0001] The present invention relates to a direct methanol fuel cell,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a carbon dioxide removing apparatus for a direct methanol fuel cell, and more particularly, to a carbon dioxide removing apparatus for a direct methanol fuel cell capable of effectively discharging carbon dioxide generated in an oxidation reaction of a fuel cell, will be.

2. Description of the Related Art In recent years, due to the rapid spread of portable electronic devices and wireless communication devices, there has been much interest and research in development of a portable power supply device and a fuel cell for power generation as a clean energy source.

A fuel cell is a new generation system that directly converts energy generated by electrochemically reacting a fuel gas (hydrogen or methanol) with an oxidizer (oxygen or air) into electric energy.

Such a fuel cell is classified into a phosphoric acid fuel cell, a molten carbonate fuel cell, a solid oxide fuel cell, a polymer electrolyte fuel cell, an alkaline fuel cell, and a direct methanol fuel cell depending on the type of electrolyte used. Each of these fuel cells operates fundamentally on the same principle, but there is a difference between the type of fuel used, the operating temperature, the catalyst, and the electrolyte.

Among these direct methanol fuel cells (DMFCs), since methanol is used as fuel, it is not necessary to use a hydrogen reformer, and it is also possible to operate at a low temperature. In particular, the direct methanol fuel cell has a simpler fuel supply system and simpler apparatus than other types of fuel cells, enabling miniaturization and more compact configuration. Therefore, the direct methanol fuel cell has a merit that it can be widely applied to household, mobile equipment, portable power supply, and military use.

Among these direct liquid fuel cells, a direct methanol fuel cell using methanol and water as a fuel is an oxidation reaction in which a fuel is oxidized as an electrode reaction (an anode electrode reaction) and a reduction in hydrogen ions and oxygen A reduction reaction (cathode electrode reaction) occurs. In the oxidation reaction, methanol and water react with each other to generate carbon dioxide, hydrogen ions, and electrons, and the generated hydrogen ions are transferred to the cathode electrode through the electrolyte membrane. In the reduction reaction, hydrogen ions, electrons transferred through an external circuit, and oxygen supplied separately react to produce water. Thus, the overall reaction of a direct methanol fuel cell is a reaction in which methanol and oxygen react to produce water and carbon dioxide.

On the other hand, the fuel cell can be classified into an active type and a passive type according to its configuration. The active type is a method of supplying and circulating methanol or air as a fuel to a fuel cell by using a pump or a fan, and the configuration is complicated, but it is advantageous that a large power can be easily obtained. On the other hand, the passive type has advantages in that the fuel cell and the air are supplied to the fuel cell by using convection or concentration gradient without using a separate supply device, so that the configuration is simple and suitable for miniaturization. In addition, such a passive type is operated at room temperature for a portable device, and the electric power obtained is smaller than that of the active type.

1 is a view for explaining the circulation of fuel and the process of removing carbon dioxide in a passive fuel cell system.

1, a passive fuel cell system includes a membrane electrode assembly 100, current collectors 110a and 110b, a cathode plate 120, a fuel storage layer 130, and a carbon dioxide removing device 200 do. The membrane electrode assembly 100 is composed of an electrolyte membrane 101 and a cathode electrode 102 and an anode electrode 103 which are disposed closely to both surfaces of the electrolyte membrane 101 with the electrolyte membrane 101 interposed therebetween do.

The operation of the passive direct methanol fuel cell system will be described with reference to FIG.

First, fuel is supplied from the fuel storage layer 130 to the anode electrode 103 through the anode current collector 110b. In the anode electrode 103, hydrogen ions, electrons, and carbon dioxide are generated by the oxidation reaction. The generated electrons are moved to the cathode electrode 102 through an external circuit (not shown) through the current collectors 110a and 110b and the anode electrode 103 is moved through the electrolyte membrane 101 in the cathode electrode 102. [ And water is generated by the reduction reaction in which the electrons and the oxygen meet each other.

The carbon dioxide produced in the anode electrode 103 is transferred to the carbon dioxide removing unit 200 together with the unreacted methanol solution. The carbon dioxide is discharged to the outside through a gas-liquid separator (not shown) 130 to continue to circulate.

As described above, the direct methanol fuel cell system can maintain the performance of the system only when the methanol solution is continuously supplied from the outside and the generated carbon dioxide is continuously removed. In addition, in order to be used as a portable or mobile power source, a direct methanol fuel cell system must be completely sealed, and an apparatus for recovering and removing carbon dioxide generated by the oxidation reaction at the anode electrode is indispensable.

In general, the carbon dioxide removing device is separated from the gas-liquid separator through the gas-liquid separator after the gas-like carbon dioxide and the liquid methanol-methanol solution are introduced together. The conventional fuel cell system, that is, the carbon dioxide removing device, If the gas is inclined at a predetermined angle from a predetermined position, the introduced carbon dioxide can not be smoothly discharged.

An object of the present invention is to provide a direct methanol fuel cell carbon dioxide removing device capable of effectively discharging carbon dioxide generated in an oxidation reaction regardless of the direction in which the fuel cell is placed.

According to an aspect of the present invention,

A body having a hollow and at least a part of which is opened, at least a part of the other surface is opened, all surfaces of the other surface are closed, and a plurality of through holes are formed in the outer surface so as to communicate with the hollow;

A gas-liquid separator disposed on an outer circumferential surface of the body so as to cover the plurality of through-holes; And

And a mesh disposed on the gas-liquid separation membrane.

According to an embodiment of the present invention, an inlet and an outlet are disposed on one side and the other side of the body, respectively, or on one side of the body so as to communicate with the hollow.

According to another embodiment of the present invention, the inner width of the inlet and the outlet are narrower than the width of the hollow.

According to another embodiment of the present invention, the gas-liquid separation membrane is a porous membrane having a plurality of pores formed therein.

According to another embodiment of the present invention, the pores of the gas-liquid separation membrane have a diameter ranging from 0.1 to 10 mu m.

According to another embodiment of the present invention, the gas-liquid separator is a hydrophobic polymer membrane.

According to another embodiment of the present invention, at least a part of each corresponding bottom surface is opened or at least a part of the bottom surface of each of the two bottom surfaces is opened and the other bottom surface is covered with a cylindrical, triangular, , A pentagonal cylinder, a hexagonal cylinder, or an octagonal cylinder.

According to another aspect of the present invention,

There is provided a fuel cell having at least one carbon dioxide removing device according to any one of the above embodiments.

According to the present invention, it is possible to provide a direct methanol fuel cell carbon dioxide removing device capable of effectively discharging carbon dioxide generated during an oxidation reaction regardless of the direction in which the fuel cell is placed.

Next, a carbon dioxide removing apparatus for a direct methanol fuel cell according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of the apparatus for removing carbon dioxide for a direct methanol fuel cell according to an embodiment of the present invention, FIG. 3 is a sectional view taken along the line A-A 'of FIG. 2, FIG. 5 is a perspective view showing the carbon dioxide removing device of FIG. 2. FIG.

2 to 5, an apparatus 200 for removing carbon dioxide according to an embodiment of the present invention includes a main body 201, a gas-liquid separator 210, and a mesh 220.

The main body 201 has a hollow shape, and at least a part of one surface and at least a part of the other surface are opened, and a plurality of through holes 201a are formed on the outer circumferential surface to communicate with the hollow. Specifically, the main body 201 may have a cylindrical shape, a triangular shape, a square shape, a pentagonal shape, a hexagonal shape or an octagonal shape, or the like, in which at least a part of each corresponding bottom surface is opened. However, the present invention is not limited thereto, and although not shown here, the main body has at least a part of the bottom surface of one of the two corresponding bottom surfaces thereof being open and the other bottom surface being entirely closed, cylindrical, triangular, It may be cylindrical, hexagonal, or octagonal.

A main body groove 201b for receiving the gas-liquid separating film 210 and the mesh 220 to be described later is formed on the outer circumferential surface of the main body 201 so as to surround the main body 201 by 360 degrees. However, such a body groove 201b is not necessarily required and may be omitted.

An inlet 201c through which the carbon dioxide discharged from the fuel cell stack (not shown) and the unreacted methanol solution flows is provided on one surface of the main body 201, and a methanol solution in a state in which carbon dioxide is removed flows out from the other surface And an outlet 201d is provided. However, when the main body is formed in a cylindrical shape or the like, and at least a part of one of the bottom faces of the two corresponding bottom faces of the cylindrical body is opened and the other bottom face is completely clogged, the inlet and the outlet are opened It may be installed only on one side.

In addition, the inlet (201c) and / or outlet (201d) inside width (W _201c) of the width of the hollow fiber to facilitate gas-liquid separation to make room occur phase separation of the carbon dioxide in the liquid fuel and gas (W _h) It is preferable to be narrower. Specifically, the inner width W _201c of the inlet port 201c and / or the outlet port 201d is preferably about 1 to 10 times smaller than the hollow width W _h .

The gas-liquid separation membrane 210 is disposed on the outer circumferential surface of the main body 201 so as to cover the plurality of through-holes 201a as a film selectively permeable to carbon dioxide by suppressing permeation of the methanol solution and discharging the carbon dioxide smoothly. Specifically, in this embodiment, the gas-liquid separation membrane 210 is disposed on the outer circumferential surface of the body 201 so as to be accommodated in the body groove 201b. The gas-liquid separation membrane 210 is a porous membrane having a plurality of pores formed therein. Further, it is preferable that the pores have a diameter of 0.1 to 10 mu m, more preferably a diameter of 0.5 to 10 mu m. If the diameter of the pores is less than 0.5 mu m, the carbon dioxide is not easily discharged, and the performance of the fuel cell may deteriorate due to an increase in pressure. If the diameter exceeds 10 mu m, the methanol solution may leak to the pore together with carbon dioxide have.

Also, it is preferable that the gas-liquid separation membrane 210 is a hydrophobic polymer membrane. As the gas-liquid separation membrane 210, polyvinylidene fluoride, fluoroethylene propylene, polytetrafluoroethylene, fluorinated ethylene propylene, polychlorotrifluoroethylene, and fluoroethylene polymer can be used.

The mesh 220 is disposed on the gas-liquid separator 210 to prevent the gas-liquid separator 210 from being damaged due to contact with an external object or an increase in internal pressure of the apparatus 200. The size and thickness of the mesh 220 are not particularly limited as long as they can prevent damage to the gas-liquid separation membrane 210. However, the thickness of the mesh 220 is limited to such a degree that the mesh 220 can be completely accommodated in the body groove 201b .

Hereinafter, the operation and effect of the carbon dioxide removing device of the present invention will be described in detail with reference to FIGS. 2 to 5. FIG.

First, the carbon dioxide discharged from the fuel cell stack (not shown) and the unreacted methanol solution are introduced into the inlet 201c.

After the introduction, the carbon dioxide moves in the direction opposite to the direction of gravity because the density of the carbon dioxide is lower than that of the methanol solution regardless of the position where the carbon dioxide removing device 200 is placed, and the methanol solution moves in the gravity direction. Since the gas-liquid separation membrane 210 is disposed so as to surround the outer circumferential surface of the body 201 by 360 degrees, at least a part of the gas-liquid separation membrane 210 is in contact with the carbon dioxide, regardless of the direction in which the carbon dioxide removal device 200 is placed. So that carbon dioxide can be smoothly discharged to the outside through the gas-liquid separation membrane 210. The carbon dioxide discharged to the outside is released into the atmosphere or introduced into a separate collecting device.

Meanwhile, the introduced methanol solution is re-introduced into the fuel cell stack through the outlet 201d in a state in which the carbon dioxide is removed.

The size and the number of the carbon dioxide removing apparatus having the above-described configuration are not particularly limited. One of them may be used alone, or in consideration of the amount of carbon dioxide discharged according to the power density required by the direct methanol fuel cell system More than one can be connected in series or in parallel.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples.

Example

Example 1: Time-dependent power density change test

The direct methanol fuel cell used a fuel cell system as shown in Fig. 1 connecting the carbon dioxide removal device of Fig. The membrane-electrode assembly 100 of the fuel cell was manufactured using a conventional method known in the art, and a platinum-ruthenium alloy catalyst manufactured by Dongjin Semichem was used as the anode catalyst, and a platinum- The prepared platinum-cobalt catalyst was used. As the polymer electrolyte membrane 101, Nafion 211 manufactured by DuPont was used. As the electrode support (not shown), 24AA (anode) and 24BC (cathode) of SGL were used and the electrode area was 4.84 cm ² . A thermocompression process was performed at 110 캜 for 3 minutes to manufacture the membrane-electrode assembly 100. As the gas-liquid separator, porous polytetrafluoroethylene having a pore size of 3 μm was used, and the area of the prepared gas-liquid separator was 4 cm ² .

The change in current density with time was measured by operating the fuel cell system, and the results are shown graphically in FIG. During the operation of the fuel cell system, a current of 700 mA was applied for 1 hour. In addition, the concentration of the used methanol solution was 2.5M and the on-off operation of the current was repeated at a cycle of 10 minutes.

Referring to FIG. 6, it can be seen that the power density was maintained almost constant for 1 hour. That is, from the above results, it can be seen that the performance of the fuel cell system is maintained constant for one hour, which proves that carbon dioxide is smoothly discharged from the carbon dioxide removing device.

On the other hand, although it was observed whether or not the methanol solution was leaked through the gas-liquid separation membrane, it was confirmed that no leakage occurred.

Example 2: Change in current density according to area of gas-liquid separation membrane

The size of the gas-liquid separator was sequentially increased to 4, 8, 12, and 16 cm ² in the same fuel cell system as in Example 1. The power density was measured in the same manner as in Example 1, Respectively.

Referring to FIG. 7, it can be seen that as the area of the gas-liquid separator increases, the power density increases proportionally. From these results, it can be seen that as the area of the gas-liquid separation membrane increases, the amount of carbon dioxide emissions increases. Therefore, it is preferable to make the area of the gas-liquid separation membrane as large as possible in the production of the carbon dioxide removing device.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, There will be. Accordingly, the scope of protection of the present invention should be determined by the appended claims.

1 is a view for explaining the circulation of fuel and the process of removing carbon dioxide in a passive fuel cell system.

2 is a cross-sectional view of an apparatus for removing carbon dioxide for a direct methanol fuel cell according to an embodiment of the present invention.

3 is a cross-sectional view taken along line A-A 'in Fig.

FIG. 4 is a perspective view showing only the main body of the carbon dioxide removing device of FIG. 2; FIG.

5 is a perspective view showing the carbon dioxide removing device of FIG. 2. FIG.

FIG. 6 is a graph showing changes in current density with time in the operation of a direct methanol fuel cell employing the carbon dioxide removing device having the configuration of FIG. 2. FIG.

FIG. 7 is a graph showing changes in current density according to the area of the gas-liquid separator when the direct methanol fuel cell employing the carbon dioxide removing device having the structure of FIG. 2 is operated.

Description of the Related Art

100: Membrane Electrode Assembly 101: Polymer Electrolyte Membrane

102: cathode electrode 103: anode electrode

110a: cathode current collector 110b: anode current collector

120: cathode plate 130: fuel storage layer

200: carbon dioxide removing device 201:

201a: Through hole 201b: Main body groove

201c: Inlet 201d: Outlet

210: gas-liquid separator 220: mesh

Claims (8)

A body having a hollow and at least a part of which is opened, at least a part of the other surface is opened, all surfaces of the other surface are closed, and a plurality of through holes are formed in the outer surface so as to communicate with the hollow; A gas-liquid separator disposed on an outer circumferential surface of the body so as to cover the plurality of through-holes; A mesh disposed on the gas-liquid separation membrane; And And an inlet port and an outlet port disposed on one surface and the other surface of the body so as to communicate with the hollow or on one surface of the body, The mesh serves to prevent the gas-liquid separator from being damaged, Wherein the gas-liquid separator is disposed so as to surround the outer circumferential surface of the body by 360 DEG, Wherein the main body has a constant diameter, a plurality of protrusions are formed in the main body, Wherein the inner width of the inlet and outlet is 1 to 10 times greater than the width of the hollow. delete delete The method according to claim 1, Wherein the gas-liquid separation membrane is a porous membrane having a plurality of pores formed therein. 5. The method of claim 4, Wherein the pore of the gas-liquid separation membrane has a diameter of 0.1 to 10 mu m. The method according to claim 1, Wherein the gas-liquid separation membrane is a hydrophobic polymer membrane. The method according to claim 1, The body is characterized in that at least a part of each corresponding bottom surface is open or at least a part of one of the bottom surfaces is open and the other bottom surface is a completely closed cylindrical, . A fuel cell comprising at least one carbon dioxide removing device according to any one of claims 1 to 7.

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