KR20070043242A - Semi passive type fuel cell system - Google Patents

Abstract

The present invention relates to a semi-passive fuel cell system, and in particular, a duct is formed to connect the blowing means and the upper part of the stack to serve as an air passage, and the air flow is converted in a direction perpendicular to the air flow direction on the inner surface of the duct. The present invention relates to a semi-passive fuel cell system in which a means is formed so that air is uniformly supplied to each air passage of the bipolar plate.

Fuel Cell, Semi Passive, Blower, Duct, Air Flow Conversion Means

Description

Semi Passive Type Fuel Cell System

1 is an overall schematic diagram of a semi-passive fuel cell system according to an embodiment of the present invention.

2 is a perspective view of a stack according to an embodiment of the present invention.

3 is an exploded perspective view of the stack of FIG. 2.

4 is a perspective view illustrating a coupling relationship between the stack and the blower of FIG. 1.

5 is a cross-sectional view taken along the line A-A of FIG.

6 is a cross-sectional view showing the flow of air in the stack and the blowing means.

7 is a computer model for evaluating the flow rate of air in the stack of the fuel cell system according to an embodiment of the present invention.

8 is a result of calculating the flow velocity for each position of the stack through numerical analysis with respect to the model diagram of FIG.

9 shows a schematic view of a stack and blowing means in a conventional semi-passive fuel cell system.

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

10-stack 12-MEA

13, 13a, 13b anode electrode 14, 14a, 14b cathode electrode

16-bipolar plate 19, 19a, 19b-air passage

30-fuel supply

50-Air supply means 51-Blowing means

61-1st duct 65-Airflow conversion means

71-2nd duct

[Patent Document 1] Japanese Patent Laid-Open No. 2001-6717

The present invention relates to a semi-passive fuel cell system, and in particular, a duct is formed to connect the blowing means and the upper part of the stack to serve as an air passage, and the air flow is converted in a direction perpendicular to the air flow direction on the inner surface of the duct. The present invention relates to a semi-passive fuel cell system in which a means is formed so that air is uniformly supplied to each air passage of the bipolar plate.

A fuel cell is a power generation system that directly converts the chemical reaction energy of hydrogen and oxidant contained in hydrocarbon-based materials such as methanol, ethanol, and natural gas into electrical energy.

The fuel cell system is typically referred to as a polymer electrolyte fuel cell (PEMFC) system and a direct methanol fuel cell (DMFC). A system.

In general, a PEMFC system includes a stack that generates electric energy by a reaction of hydrogen and oxygen, and a reformer that generates hydrogen by reforming a fuel. The PEMFC system has the advantages of high energy density and high output, but requires attention to handling hydrogen gas and fuel reformer for reforming methane, methanol and natural gas to produce hydrogen, fuel gas. You will need additional equipment.

In contrast, DMFC systems generate methanol by electrochemical reactions by directly supplying methanol fuel and oxygen as an oxidant to the stack. The DMFC system has a very high energy density and power density, and since liquid fuel such as methanol is directly used, no additional equipment such as a fuel reformer is required, and the fuel is easily stored and supplied.

This DMFC system is forced to supply air to the stack by using an air supply means such as an air compressor or an air pump. The DMFC system is portable, and its applicability to mobile devices such as laptops and mobile communication devices is being examined. However, the air supply means used in such a DMFC system has a problem that the noise is so severe that the user is uncomfortable due to the noise. Accordingly, such a DMFC system has been developed a passive DMFC system in which air to be supplied to the stack is supplied by natural convection, or a semi-passive DMFC system in which air is supplied by a blowing means such as a blower.

Since the passive DMFC system supplies air by natural convection, air is not supplied to each cathode sufficiently. Therefore, the passive DMFC system has a constraint that the stack is formed relatively in a planar manner without stacking the stacks.

On the other hand, since the semi-passive DMFC system uses a blowing means such as a blower, the amount of air supplied is increased compared to the passive DMFC fuel cell system. Thus, the semi-passive DMFC fuel cell system can be formed by stacking stacks. Japanese Patent Laid-Open No. 2001-6717 (Patent Document 1) discloses a fuel cell body in which a pair of electrodes composed of a fuel electrode and an oxidizer electrode is incorporated (see Fig. 9). Referring to Fig. 9, air supply means 5 for introducing an oxidant gas to the oxidant inlet side is provided to compensate for the consumption of oxygen by the electrode reaction in the oxidant electrode of the fuel cell body 1, and the oxidant Disclosed is a configuration in which the cross-sectional area of the oxidant gas flow path formed at the pole becomes smaller from the inlet to the outlet of the oxidant gas.

However, such a semi-passive DMFC system has a problem that it is difficult to uniformly supply air to the air passages formed in the bipolar plate of the stack even when using a blower. In addition, the semi-passive DMFC system has a problem that the amount of air supplied for each air passage is non-uniform due to the difference in resistance of the air flow according to the position of the air passage.

The present invention is to solve the problems as described above is connected to the upper portion of the blowing means and the stack is formed a duct to act as a passage, the air flow conversion means in a direction perpendicular to the flow direction of the air on the inner surface of the duct It is an object of the present invention to provide a semi-passive fuel cell system that is formed so that the air is uniformly supplied to each air passage of the bipolar plate.

In order to solve the above problems, the semi-passive fuel cell system of the present invention has a membrane-electrode assembly having a cathode electrode and an anode electrode formed on both sides of the electrolyte membrane and the electrolyte membrane and both sides of the membrane-electrode assembly. In a fuel cell system comprising a stack formed by sequentially stacking a plurality of unit cells having a bipolar plate disposed in the fuel cell, and a fuel supply means and an air supply means, the bipolar plate of the stack is in contact with the cathode electrode An air passage formed to penetrate from an upper portion to a lower portion, and the air supply means includes a duct installed at upper and lower portions of the stack, a blowing means installed at one side of the duct to supply air to the duct, and the duct Air flow formed at a predetermined distance away from the blowing means in the interior of the It characterized in that it comprises a ring means. At this time, the air passage of the bipolar plate may be formed in a straight shape from the top to the bottom of the stack.

In addition, in the present invention, the duct has a first duct installed in the upper portion of the stack and a second duct installed in the lower portion of the stack, the blowing means to blow air from one side of the first duct to the other side Can be formed. The first duct is provided with the blowing means inside one side, the other side is formed so as to cover the entire upper portion of the stack, an air inlet formed on the upper side of the blowing means on the upper surface of one side of the first duct; The lower surface of the other side may be formed in a shape corresponding to the lower shape of the stack and may be provided with an air supply port for supplying air to the stack. In addition, the other upper surface of the first duct may be formed to be inclined at a predetermined inclination angle so that the inner height gradually decreases from one side where the blowing means is installed to the other end.

In addition, in the present invention, the air flow converting means may be formed to extend in the width direction of the first duct and protrude to a predetermined height in the vertical direction from the top to the bottom. In this case, the air flow conversion means may be formed in the central region of the other side of the first duct. In addition, the air flow converting means may be formed by protruding the upper surface of the other side of the first duct to be integral with the first duct, or by forming a separate block coupled to the upper surface of the other side of the first duct. In addition, the air flow conversion means may be formed so that the cross-sectional shape is semi-circular or triangular. In addition, the air flow converting means may be formed such that the front surface directly contacting the air forms an obtuse angle with the air flow direction or an arc shape. In addition, the height of the air flow converting means may be formed to 30 to 70% of the height inside the first duct at the position where the air flow converting means is installed.

In the present invention, the second duct is formed in a shape corresponding to the lower shape of the stack on the upper surface and has an air inlet through which air passing through the stack is formed, and an air outlet formed at the other end to discharge the air to the outside. Can be. At this time, the lower surface of the second duct may be formed to be inclined at a predetermined inclination angle so that the inner height is increased from one end to the other end. In addition, the lower surface of the second duct may preferably be inclined at the same inclination angle as the upper surface of the first duct.

In addition, in the present invention, the blowing means may be formed with a blower or a fan.

In addition, the fuel cell system in the present invention may be made of a direct methanol fuel cell system or a polymer electrolyte fuel cell system.

Hereinafter, a fuel cell system according to the present invention will be described in detail with reference to the accompanying drawings and embodiments.

1 is an overall schematic diagram of a semi-passive fuel cell system according to an embodiment of the present invention. 2 is a perspective view of a stack according to an embodiment of the present invention. 3 is an exploded perspective view of the stack of FIG. 2. 4 is a perspective view illustrating a coupling relationship between the stack and the blower of FIG. 1. 5 is a cross-sectional view taken along the line A-A of FIG.

In the semi-passive fuel cell system according to an exemplary embodiment of the present invention, referring to FIGS. 1 to 5, the fuel supply means 30 and the stack 10 for supplying fuel to the stack 10 and the stack 10 are provided. It is formed including an air supply means 50 for supplying air to the. This section focuses on the Direct Methanol Fuel Cell (DMFC) system that generates electric energy using methanol or ethanol as a direct fuel. However, the fuel cell system according to the present invention is applied to a polymer electrolyte fuel cell (hereinafter referred to as "PEMFC") system that generates electric energy using hydrogen generated by reforming fuel as a fuel. Of course it can. However, the PEMFC system is configured to further include a reformer for generating hydrogen by reforming the liquid fuel.

The stack 10 is a unit cell including a membrane-electrode assembly (hereinafter referred to as "MEA") 12 and a bipolar plate 16 disposed on both sides of the MEA 12. It is formed by stacking a plurality of 10a. At this time, the bipolar plate 16 is formed so that the MEA 12 is in contact with both sides to be shared by the unit cells 10a adjacent to each other. In addition, the stack 10 supplies electricity to an external load through an end plate 16a, which is a bipolar plate located at outer sides of both sides. The stack 10 may be formed to include a support plate 16b coupled to the outside of the end plate 16a to fix the bipolar plate 16 and the MEA 12. The support plate 16b is provided with a predetermined passage (not shown) so that fuel supplied from the fuel supply means 30 is supplied to the bipolar plate 16. On the other hand, the end plate 16a may be formed to serve as a support plate at the same time, of course.

The stack 10 has a unit cell 10a formed on the left and right sides of the bipolar plate 16 based on the vertical center line. That is, the stack 10 is formed of unit cells independent of left and right when viewed from the front direction. In addition, the stack 10 has first and second passages 17a and 17b serving as fuel supply passages in unreacted regions formed with a predetermined width between unit cells formed at left and right sides thereof. Therefore, the stack 10 is supplied with fuel through the first passage and the second passage 17a, 17b in the lateral direction. In addition, the stack 10 is supplied with air through an air passage 19 formed from top to bottom on one surface of the bipolar plate 16. On the other hand, the stack of the unit cells formed on the left and right with respect to the vertical center line may be formed integrally. That is, the unreacted region may not be formed at the center of the stack. In this case, therefore, the stack has first and second passages 17a and 17b formed on the left and right sides of the bipolar plate 16.

The MEA 12 is formed by stacking an electrolyte membrane 14 between an anode electrode 13 and a cathode electrode 15. At this time, the anode electrode 13 and the cathode electrode 15 are spaced apart from the left and right by a vertical center line on both surfaces of the electrolyte membrane 14, respectively, and the anode electrodes 13a and 13b and the cathode electrode 15a are provided in predetermined areas. , 15b) is formed. Accordingly, the MEA 12 has an unreacted region 12a in which both an anode electrode 13 and a cathode electrode 15 are not formed at both sides thereof, and the unreacted region ( 12a), a first through passage 17a and a second through passage 17b, which are fuel supply passages through which fuel flows, are formed. In addition, the MEA 12 may have a fastening hole 20 through which a bolt for fastening the stack 10 passes between the first passage 17a and the second passage 17b.

The anode electrode 13 and the cathode electrode 15 include a fuel diffusion layer for supplying and diffusing fuel, a catalyst layer in which an oxidation / reduction reaction of the fuel occurs, and an electrode support. The anode electrode 13 separates electrons and hydrogen ions from the supplied fuel, and the electrolyte membrane 14 moves the hydrogen ions to the cathode electrode 15. The cathode electrode 15 generates water by reacting hydrogen and oxygen with electrons supplied from the anode electrode 13. Thus, the stack 10 generates electrical energy through an electrochemical reaction between hydrogen and oxygen.

The bipolar plate 16 is in close contact with the MEA 12 on both sides, the fuel passage 18 and the air passage 19 is formed on both sides. More specifically, the bipolar plate 16 has a fuel passage 18 and an air passage 19 formed in predetermined regions on both sides of the vertical center line. Accordingly, the bipolar plate 16 has unformed regions 16c and 16d in which a fuel passage 18 and an air passage 19 are not formed at the center thereof. The bipolar plate 16 is formed by contacting the anode electrode 13 of the MEA 12 on one surface and the cathode electrode 15 of the MEA 12 on the other surface. Accordingly, the bipolar plate 16 has a fuel passage 18 formed on the surface where the anode electrode 13 is in close contact with each other so that fuel is continuously supplied to the anode electrode 13. In addition, the bipolar plate 16 has an air passage 19 formed on the surface in which the cathode electrode 15 is in close contact with each other so that air is continuously supplied to the cathode electrode 15.

The bipolar plate 16 passes through the bipolar plate 16 in the unformed region 16d between the regions where the fuel passage 18 is formed and is connected to one end and the other end of the fuel passage 18, respectively. 17a and the second passage 17b are formed up and down. Therefore, the bipolar plate 16 allows the fuel supplied through the first passage 17a to be discharged through the second passage 17b after flowing through the fuel passage 18. The first passage 17a and the second passage 17b are formed at the same position in each of the bipolar plates 16 and the MEA 12 to form a passage of fuel that passes through the upper and lower portions of the stack 10 as a whole. do. Therefore, the stack 10 is supplied with fuel through the first through passage 17a at one side, and unreacted fuel and carbon dioxide as a reaction byproduct are discharged through the second through passage 17b at the other side. The bipolar plate 16 is provided with a fastening hole 20 into which a bolt (not shown) is inserted to fasten the stack 10 between the first passage 17a and the second passage 17b. . The first passage 17a and the second passage 17b are connected to the fuel supply means 30 through a predetermined passage (not shown) formed in the support plate 16b to allow fuel to flow. The passage formed in the support plate 16b may be formed in various ways according to the design of the stack 10.

The bipolar plate 16 is formed of a metallic material, for example a metal such as aluminum, copper, iron or an alloy, graphite or carbon composite thereof.

The fuel passage 18 is formed on a surface of the bipolar plate 16, that is, in a region contacting the anode electrode 13 of the MEA 12 with a predetermined depth and width along the surface on the left and right with respect to the vertical center line. Therefore, the fuel passages 18a and 18b are formed on both sides of the unformed region 16d formed at the center, respectively. The fuel passage 18 is preferably formed in a zigzag shape so that the area of the fuel passage 18 is increased. Therefore, the fuel passage 18 increases the contact area of the anode electrode 13 of the MEA 12 and increases the area of the anode electrode 13 in which the fuel is in direct contact. Since the stack 10 is supplied with fuel at a predetermined pressure by the fuel pump, the fuel may be smoothly supplied even when the fuel passage 18 is zigzag-shaped.

The air passage 19 is the other surface of the bipolar plate 16, ie. The area in contact with the cathode electrode 15 of the MEA 12 is formed in a predetermined width, depth and shape along the surface on the left and right with respect to the vertical center line. Accordingly, the air passages 19a and 19b are formed at both sides of the unformed region 16c formed at the center, respectively. The air passage 19 is preferably formed in a straight shape from the top to the bottom so that the air supplied from the top or bottom can flow smoothly. The air passage 19 is not connected to the first passage 17a and the second passage 17b unlike the fuel passage 18 on one surface.

Meanwhile, the MEA and the bipolar plate may not have a central unreacted region or an unformed region. That is, in the MEA, anode and cathode electrodes respectively formed on one surface and the other surface may be integrally formed without an unreacted region. In addition, the bipolar plate may be formed integrally with the fuel passage and the air passage formed on one surface and the other surface, respectively, without a central unformed region. In this case, the stack has a first passageway and a second passageway formed on the left and right sides of the bipolar plate and the MEA.

The fuel supply means 30 is formed to include a fuel tank 32 for storing fuel diluted to a predetermined concentration and a fuel pump 34 for supplying fuel to the stack 10. In addition, when the fuel tank is formed to be diluted to a predetermined concentration by mixing the fuel feed solution and water supplied separately, the fuel supply means 30 and the fuel feed tank (not shown) to store the fuel feed solution and It may be formed by further comprising a stock pump (not shown). On the other hand, the fuel tank 32 may be formed in the form of a cartridge in which the fuel diluted to a predetermined concentration is stored. In this case, when the fuel stored in the fuel tank 32 is exhausted, the fuel may be recharged or a new fuel tank may be installed.

The fuel tank 32 stores a liquid fuel such as methanol or ethanol diluted to a predetermined concentration. The fuel pump 34 is connected to the fuel tank, and supplies the fuel of the fuel tank 32 to the anode electrode of the stack 10. In addition, when the fuel tank is supplied with a fuel stock solution and diluted to a predetermined concentration, the fuel tank 32 may include unreacted fuel discharged from the anode electrode of the stack 10 and water discharged from the cathode electrode of the stack 10. This is connected to the anode electrode and the cathode electrode of the stack 10 by a separate pipe so as to recover.

The air supply means 50 is a duct 60 and the duct 51 for supplying the blowing means 51 for sucking and blowing air and the air blown out of the blowing means 51 to the upper or lower portion of the stack 10. It is formed including the air flow conversion means 65 for converting the flow of air in the).

The blowing means 51 sucks the outside air and blows it out at a predetermined pressure, and is formed as a blower or a fan. However, the blowing means 51 may of course be used a variety of means for blowing air at a predetermined pressure.

The duct 60 includes a first duct 61 formed at an upper portion of the stack 10 and a second duct 71 installed at a lower portion of the stack 10, and the inside of the first duct or the second duct. Or the blowing means 51 is installed outside. The duct 60 guides the air supplied from the blowing means 51 installed at one side of the first duct to the upper portion of the stack 10 and supplies the air to the air passage 18. Here, the first duct 61 is formed at the upper portion and the second duct 71 is formed at the lower portion. However, the first duct is formed at the lower portion according to the specification or the method of use of the mobile communication device used. Of course, the second duct may be formed on the upper portion.

The first duct 71 is formed in a substantially plate-shaped box shape with a hollow inside, a blowing means 51 is installed inside or outside one side, and the other side is formed to cover the upper portion of the stack 10. (Here, one side of the first duct means a left side in which the blowing means is installed in the Figure 5 and away from the top of the stack, the other side means the right side portion is installed on the top of the stack) The first duct 61 is one side Preferably, the blower means 51 is formed at a height corresponding to the height of the blower means 51, and the blower means 51 is installed therein, and an air suction port 62 for suctioning air from the blower means 51 is formed on the upper surface thereof. The air suction port 62 is preferably formed with an area corresponding to the upper area of the blowing means 51. At this time, one side of the first duct 61 is formed to have a uniform height as a whole so that the sucked air flows smoothly to the other side. In addition, one end 61a of the first duct 61 is closed to prevent the air sucked by the blowing means 51 from flowing out. Therefore, the first duct 61 allows the air sucked by the blowing means 51 to be ejected only to the other side.

The other side of the first duct 61 is formed to have a predetermined height and an area corresponding to at least an upper area of the stack 10 so as to cover the entire upper portion of the stack 10. At this time, the other side of the first duct 61 is opened in the lower region in contact with the upper portion of the stack 10 is formed with an air supply port (63). The air supply port 63 is preferably formed in a shape and area corresponding to the top shape and area of the stack. Thus, the first duct 61 is the air intake of the stack 10 through the air supply port 63 by the air sucked through the air inlet 62 of one side by the blowing means 51 is directed to the other side ( 18).

The other side of the first duct 61 is preferably formed such that the height inside thereof gradually decreases from one side of the stack 10 to the other side. That is, the other side of the first duct 61 is formed such that the upper surface 61c is inclined at a predetermined inclination angle with respect to the upper surface of the stack 10. Therefore, as the other side of the first duct 61 moves away from the blowing means 51, the cross-sectional area is reduced so that the velocity of air blown out of the blowing means 51 is not reduced. In general, when the cross-sectional area of the duct is constant, the ejected air is reduced in speed as it moves away from the blowing means, and the supply amount of air is reduced. This phenomenon increases as the amount of air blown out of the blowing means decreases. Accordingly, the other side of the first duct 61 may be appropriately formed according to the amount of air blown out from the blowing means 51 by the inclination angle of the upper surface 61c. That is, when the amount of air blown out by the blowing means 51 increases, the other side of the first duct 61 may have a lower inclination angle at the upper surface 61c. On the contrary, when the amount of air blown out by the blowing means 61 is small, the inclination angle of the upper surface 61c of the other side of the first duct 61 may be large.

Like the first duct 61, the second duct 71 is formed in a substantially plate-shaped box shape with a hollow inside. The second duct 71 is installed below the stack 10 to cover the bottom of the stack 10, and an air inlet 73 having an area corresponding to the bottom area of the stack 10 is formed on an upper surface thereof. . In addition, one end 71a of the second duct 71 is closed and the other end 71b of the second duct 71 is formed as an air outlet 72. Therefore, the second duct 71 discharges the air passing through the stack 10 to the outside.

In addition, the second duct 71 is formed to be inclined at a predetermined inclination angle from the one end (71a) to the other end (71b) when the internal height is gradually increased. In this case, the air introduced into the second duct 71 may be discharged smoothly as the air velocity at one end 71a is relatively faster than the other end 71c. The lower surface 71c of the second duct 71 is preferably inclined at an inclination angle corresponding to the inclination angle of the other upper surface 61c of the first duct 61. Therefore, the height of the fuel cell system is uniformly formed as a whole, and the height can be prevented from being partially increased by the duct 50. In this case, the stack 10 is inclined at an angle corresponding to the inclination angle of the top surface of the first duct 61 or the bottom surface of the second duct 71.

On the other hand, the second duct serves as a drain passage for the water discharged after the reaction from the cathode of the stack (10). Therefore, a separate pipe for recovering such water may be formed at the other end of the second duct.

The air flow converting means 65 is formed at a predetermined position on the other upper surface 61c of the first duct 61 to change the flow direction of the air supplied from the blowing means 51. More specifically, the air flow converting means 65 is formed to extend in the width direction of the first duct 61 perpendicular to the flow direction of the air inside the upper surface 61c of the other side of the first duct 61, It protrudes from a top to a predetermined height and is formed. The air flow converting means 65 partially converts the flow of air ejected from the blowing means 51 in the downward direction, that is, the vertical direction. In the other side of the first duct 61, air flows in the other end 61b and then flows in the direction of the stack 10 at the position where the air flow converting means 65 is formed. Therefore, the air flowing in the direction of the other end 61b of the first duct 61 is relatively reduced in speed as the flow direction is changed. In addition, since the air flowing in the direction of the other end 61b of the first duct 61 is blocked by the air flow converting means 65, the amount of air flowing to the other end 61b is relatively reduced. The air flow converting means 65 converts the flow of air at the top of the stack 10 to relatively reduce the speed and amount of air flowing to the other end. Therefore, the air passages 19a and 19b formed at both sides of the bipolar plate 16 can supply a relatively uniform amount of air.

The air flow converting means 65 is preferably formed at a substantially central position on the other side of the first duct 61. That is, the air flow converting means 65 is provided above the unreacted region 12a or the unformed regions 16d and 16d formed at the approximately center position of the stack 10. Accordingly, the air flow converting means 65 uniformly supplies air to the air passages 19a and 19b formed at one side and the other side of the bipolar plate 16.

The air flow converting means 65 may be formed by protruding the upper surface 61c of the first duct 61 to be integrally formed with the upper surface 61c of the first duct 61. At this time, the air flow conversion means 65 may be formed so that the cross-sectional shape is approximately a semi-circle, to minimize the portion of the air flow discontinuously. In addition, the air flow converting means 65 is formed so that the front surface 65a in direct contact with the air has an approximately arc shape or an obtuse angle with the flow direction of the air, thereby preventing the air flow from being excessively blocked. . In this case, the air flow converting means 65 is formed so that the cross section is triangular in shape, thereby minimizing the space occupied in the first duct 61. Meanwhile, the air flow converting means 65 may be formed by a separate block coupled to the upper surface 61c of the first duct 61.

The air flow converting means 65 may have a height protruding from the upper surface 61c of the other side of the first duct 61 at a height inside the first duct (more precisely, at a position where the air flow converting means 65 is installed). 30 to 70% of the inner height of the duct). When the height of the air flow converting means 65 is smaller than 30% of the internal height of the first duct, the degree of air flow converting becomes small and the effect of installing the air flow converting means 65 is reduced. In addition, when the height of the air flow conversion means 65 is greater than 70% of the height inside the first duct, the flow conversion degree of the air is too large, the air passage (19b) located on the other side of the bipolar plate 16 The amount of air supplied is relatively small.

Next, the operation of the fuel cell system according to the exemplary embodiment of the present invention will be described.

6 is a cross-sectional view showing the flow of air in the stack and the blowing means. 7 is a computer model for evaluating the flow rate of air in the stack of the fuel cell system according to an embodiment of the present invention. 8 is a result of calculating the flow velocity for each position of the stack through numerical analysis with respect to the model diagram of FIG. Here, the air supply means 50 will be described with reference to a method for supplying air to the stack 10. On the other hand, the method for supplying fuel to the stack 10 by the fuel supply means 30 is used since a general method known to those skilled in the art, the detailed description thereof will be omitted here.

The duct 60 has a first duct 61 coupled to the upper portion of the stack 10, and a second duct 71 coupled to the lower portion of the duct 60. The first duct 71 has a blowing means 51 is mounted on one side, the other side is coupled to the upper portion of the stack (10). Therefore, when the blower means 51 is operated, the blower means 51 sucks air through the upper air suction port 62 and blows it to the other side of the first duct 61 through the side of the blower means 51. Done. The first duct 61 allows the air blown out through the blowing means 51 to flow to the other side. Since the upper surface 61c is inclined at the other side of the first duct 61, the speed of air may not be reduced even in the other end 61b region. However, the air flow converting means 65 converts the flow of air flowing inside the first duct 61 to relatively reduce the speed and the amount of air flowing to the other end region. Therefore, the air passages 19a and 19b formed at one side and the other side of the bipolar plate receive a uniform amount of air. That is, the air flow converting means 65 equalizes the amount of air supplied to the air passages 19a and 19b located at one side and the other side with respect to the air flow converting means 65.

Air passing through the first duct 61 flows into the lower portion of the stack 10 and flows into the second duct 71 through the air inlet 73 of the second duct 71. Since the air passage 19 of the bipolar plate 16 is formed in a straight line in the vertical direction, air flows more smoothly. One side of the second duct 71 is coupled to the lower portion of the stack 10 so that air discharged from the stack 10 flows to the other side. At this time, the second duct 71 has an internal height increases from one end (71a) to the other end (71b), so that the air discharged from the stack 10 flows smoothly from one end (71a) to the other end (71b). Air flowing from one end of the second duct 71 to the other end is discharged to the outside through an air outlet 72 formed at the other end.

As described above, the present invention is not limited to the specific preferred embodiments described above, and any person having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Various modifications are possible, of course, and such changes are within the scope of the claims.

According to the fuel cell system according to the present invention, the duct having an inclined top surface is provided with air flow converting means installed in the duct at a predetermined position above the stack to convert air flow inside the duct to supply air to the other side of the bipolar plate. By controlling the speed and the amount, there is an effect that the air can be uniformly supplied to the air passage of the bipolar plate regardless of the position of the air passage.

Claims (17)

 A stack formed by sequentially stacking a plurality of unit cells including an electrolyte membrane, a membrane-electrode assembly including a cathode electrode and an anode electrode formed on both sides of the electrolyte membrane, and a bipolar plate disposed on both sides of the membrane-electrode assembly. In the fuel cell system comprising a fuel supply means and an air supply means, The bipolar plate of the stack has an air passage formed to penetrate from the top to the bottom in contact with the cathode electrode, The air supply means is a duct installed in the upper and lower portions of the stack, a blowing means for supplying air to the duct is provided on one side of the duct, and formed in a position away from the blowing means in the interior of the duct Semi-passive fuel cell system comprising an air flow conversion means. The method of claim 1, Semi-passive fuel cell system, characterized in that the air passage of the bipolar plate is formed in a straight shape from the top to the bottom of the stack. The method of claim 1, The duct includes a first duct installed in the upper portion of the stack and a second duct installed in the lower portion of the stack, The blowing means is a semi-passive fuel cell system, characterized in that formed to blow air from one side of the first duct to the other side. The method of claim 3, wherein The first duct is provided with the blowing means inside one side, the other side is formed to cover the entire upper part of the stack, An air inlet formed in an upper portion of the blower means on an upper surface of one side of the first duct, and an air supply hole formed in a shape corresponding to a lower shape of the stack on a lower surface of the other side and supplying air to the stack; Semi-passive fuel cell system characterized by. The method of claim 3, wherein Semi-passive fuel cell system, characterized in that the other upper surface of the first duct is formed to be inclined at a predetermined inclination angle so that the inner height is gradually reduced from one side where the blowing means is installed to the other end. The method of claim 5, The air flow converting means extends in the width direction of the first duct and is semi-passive fuel cell system, characterized in that formed to protrude at a predetermined height in the vertical direction from the top to the bottom. The method of claim 6, The air flow conversion means is a semi-passive fuel cell system, characterized in that formed in the central region of the other side of the first duct. The method of claim 6, The air flow converting means is a semi-passive fuel cell system, characterized in that the upper surface of the other side of the first duct protrudes inwardly and integrally formed with the first duct. The method of claim 6, The air flow conversion means is a semi-passive fuel cell system, characterized in that a separate block is formed by being coupled to the upper surface of the other side of the first duct. The method according to claim 8 or 9, The air flow converting means is a semi-passive fuel cell system, characterized in that the cross-sectional shape is formed in a semicircle or triangle shape. The method according to claim 8 or 9, The air flow converting means is a semi-passive fuel cell system, characterized in that the front surface in direct contact with the air is formed to form an obtuse angle or an arc shape with the air flow direction. The method of claim 6, The air flow converting means is a semi-passive fuel cell system, characterized in that the projecting height is formed 30 to 70% of the height inside the first duct at the position where the air flow converting means is installed. The method of claim 3, wherein The second duct is formed in a shape corresponding to the lower shape of the stack on the upper surface and has an air inlet through which air passing through the stack is introduced, and an air outlet formed at the other end to discharge the air to the outside. Semi-passive fuel cell system. The method of claim 13, Semi-passive fuel cell system, characterized in that the lower surface of the second duct is inclined at a predetermined inclination angle so that the inner height is increased from one end to the other end. The method of claim 14, Semi-passive fuel cell system, characterized in that the lower surface of the second duct is inclined at the same inclination angle as the upper surface of the first duct. The method of claim 1, Semi-passive fuel cell system, characterized in that the blowing means is provided with a blower or a fan. The method of claim 1, The fuel cell system is a semi-passive fuel cell system, characterized in that consisting of a direct methanol fuel cell system or a polymer electrolyte fuel cell system.

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