KR20030018078A - Structure for humidifying hydrogen in fuel cell stack - Google Patents

Abstract

PURPOSE: A hydrogen humidification apparatus for fuel cell stack is provided, to reduce the equipment space and the weight occupied by a humidification apparatus and to lower the manufacturing cost by forming a plurality of micropaths. CONSTITUTION: The hydrogen humidification apparatus humidifies the hydrogen gas supplied to the each unit cell and comprises a separation plate(25) of the each unit cell, and the separation plate(25) comprises a plurality of micropaths which are formed between the cooling water inlet hole(253c) of the cooling water entrance path of the cell assembly of a fuel cell engaged with the cooling water supply port of an end plate and the hydrogen inlet hole(253a) of an hydrogen entrance path. The cooling water passing through the cooling water entrance path via the micropaths(257) is inhaled and sprayed into the hydrogen entrance path.

Description

Structure for humidifying hydrogen in fuel cell stack

The present invention relates to a hydrogen humidifying structure of a fuel cell stack, and more particularly, to form a cooling water inlet passage and a hydrogen inlet passage of a fuel cell assembly in which unit cells are stacked in order to humidify hydrogen supplied to a fuel cell stack. By forming a plurality of micropaths between the cooling water inlet hole and the hydrogen inlet hole of each separator plate, a separate external humidifier is not required, thereby reducing the space and weight occupied by the humidifier and required for the construction of a fuel cell stack. The invention relates to a hydrogen humidifying structure of a fuel cell stack, which can also reduce costs.

In general, a fuel cell stack is a device that directly converts fuel into electrical energy electrochemically, and is a pollution-free power generation device that is interested in researching power sources of automobiles and power supplies of laser electric appliances.

The fuel cell stack 1 includes end plates 12 and 14 disposed at both ends and end plates 12 and 14, as shown in FIG. And a predetermined fastening structure 30 for maintaining the airtightness and pressing force of the fuel cell assembly 20 disposed therebetween.

Here, the fuel cell assembly 20 has a structure in which unit cells 22 for generating electricity are stacked, and each unit cell 22 includes a gas diffusion layer 24, a separator plate 25, and an electrode film. (26) and the like.

In addition, each unit cell 22 is supplied with hydrogen, which is a fuel gas, oxygen, which is an oxidant, and cooling water for cooling. As shown in FIG. 5B, hydrogen and oxygen are supplied to the separator 25. Hydrogen 251a and oxygen flow path 251b in the form of a groove that can flow are formed on one surface and the other surface, respectively, and a cooling water flow path 251c is formed therein.

In general, the fuel cell stack 1 supplies the end plates 12 to supply and discharge hydrogen, oxygen, and cooling water to the fuel cell assembly 20 having a structure in which a plurality of unit cells 22 are stacked. (42a, 42b, 42c) and discharge ports (44a, 44b, 44c) are provided, each of the inlet holes of hydrogen, oxygen, and cooling water formed in the separator 25 in the state in which the unit cells 22 are stacked Corresponding supply ports 42a, 42b and 42c for hydrogen, oxygen and cooling water of the end plate 12 by means of 253a, 253b and 253c and respective outlet holes 255a, 255b and 255c (in FIGS. 4 and 5a). ), And corresponding inlet passages 43a, 43b, 43c and outlet passages 45a, 45b, 45c of hydrogen, oxygen and cooling water communicating with the discharge ports 44a, 44b, 44c are formed.

That is, each of the inlet passages 43a, 43b, 43c and the outlet passages 45a, 45b, and 45c of the fuel cell assembly 20 in which the unit cells 22 are stacked and the cooling water is hydrogen and oxygen, The unit is formed by hydrogen and oxygen formed by penetrating the separation plate 25 so that the coolant can pass therethrough, each inlet hole 253a, 253b and 253c of the coolant and the outlet holes 255a, 255b and 255c. In the state in which the batteries 22 are stacked, the inlet holes 253a, 253b and 253c and the outlet holes 255a, 255b and 255c of each of the separator plates 25 correspond to the inlet passages 43a, 43b and 43c and the outlet passages ( 45a, 45b, 45c).

Accordingly, the hydrogen 251a, the oxygen flow path 251b and the cooling water flow path 251c of each of the separation plates 25 are supplied to the supply ports 42a, 42b, 42c of the end plate 12 and the fuel cell assembly 20. Hydrogen, oxygen, and coolant are distributed through the corresponding inlet passages 43a, 43b, and 43c, respectively, and the hydrogen, oxygen, and coolant that have passed through each of the flow paths 251a, 251b, and 251c of the fuel cell assembly 20. It is discharged to the outside through the outlet passage (45a, 45b, 45c) and the discharge port (44a, 44b, 44c) of the end plate 12.

In particular, in the fuel cell stack 1 made as described above, the humidification of hydrogen supplying water to hydrogen to be injected so as to separate the electrons from the hydrogen to promote the ionization is essential.

In more detail, the hydrogen passing through the hydrogen flow path of each separator is decomposed into hydrogen cations and electrons on the surface of the membrane (MEA: Membrane Electrode Assembly), and then the hydrogen cations are oxygen of the neighboring separator through the electrode membrane. It flows toward the flow path and bonds with the anion of oxygen. As the hydrogen cation moves toward the oxygen flow path, it moves with water molecules, so that the hydrogen passing through the hydrogen flow path of each unit cell is always constant in order to adjust the appropriate humidity of the electrode membrane. It must be humidified.

In general, the humidifier 3 for hydrogen humidification is separately installed on the hydrogen supply line 7 connected to the fuel cell stack 1 from an external hydrogen tank 5, as shown in FIG. 6. As described above, since the humidifier 3 is installed outside the fuel cell stack 1 as described above, there is a problem in that the installation space and the cost of the fuel cell stack are large.

Accordingly, the present invention has been invented to solve the above problems, and in order to humidify the hydrogen supplied to the fuel cell stack, each of the unit cells forming the cooling water inlet passage and the hydrogen inlet passage of the fuel cell assembly in which the unit cells are stacked By forming a plurality of micropaths between the cooling water inlet hole and the hydrogen inlet hole of the separator, a separate external humidifier is not required, thereby reducing the space and weight occupied by the humidifier, and Its purpose is to provide a hydrogen humidifying structure of a fuel cell stack that can also reduce costs.

1 is a view showing a hydrogen humidifying structure of the present invention formed on a separator plate,

2A and 2B are cross-sectional views taken along the lines A-A and B-B of FIG. 1, respectively;

3 is a cross-sectional view of a typical fuel cell stack,

4 is a view showing a conventional separator;

5A and 5B are cross-sectional views taken along the lines A-A and B-B of FIG. 4, respectively;

6 is a schematic view showing a hydrogen supply line of a fuel cell stack in which a humidifier is installed.

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

1 fuel cell stack 5 hydrogen tank

7: hydrogen supply line 12, 14: end plate

20 fuel cell assembly 22 unit cell

25 separation plate 26 electrode film

42a: hydrogen supply port 42c: cooling water supply port

43a: hydrogen inlet passage 43c: cooling water inlet passage

44a: hydrogen discharge port 45a: hydrogen outlet passage

253a: hydrogen inlet hole 253c: cooling water inlet hole

255a: hydrogen outlet hole 257: fine passage

258: drainage hole 259: drainage passage

Hereinafter, the present invention will be described with reference to the accompanying drawings.

In order to achieve the above object, each unit cell 22 after being introduced from the outside through the hydrogen inlet passage 43a of the fuel cell assembly 20 communicated with the hydrogen supply port 42a of the end plate 12. In the hydrogen humidification structure of the fuel cell stack for humidifying hydrogen, which is a fuel gas supplied to the fuel cell, the cooling water supply port 42c of the end plate 12 in the separation plate 25 of each unit cell 22. A plurality of fine passages 257 between the coolant inlet hole 253c constituting the coolant inlet passage 43c of the fuel cell assembly 20 communicating with the fuel cell assembly 20 and the hydrogen inlet hole 253a constituting the hydrogen inlet passage 43a. And the cooling water passing through the cooling water inlet passage 43c through the micro passage 257 can be sucked and injected into the hydrogen inlet passage 43a.

In a preferred embodiment of the present invention, each of the separation plate 25 is formed with a drain hole 258 on one side of the lower portion of the hydrogen inlet hole 253a so that the remaining water can be discharged from the hydrogen inlet hole 253a. The discharge hole 258 is connected to the hydrogen discharge port 44a of the end plate 12 to form the hydrogen outlet passage 45a of the hydrogen cell outlet passage 45a of the fuel cell assembly 20. (255a) characterized in that it is provided with a drain passage (259) connected to the lower one side.

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

1 is a view showing a hydrogen humidifying structure of the present invention formed on a separator, and FIGS. 2A and 2B are cross-sectional views taken along the lines AA and BB of FIG. 1, respectively, and reference numeral 253a denotes a unit cell 22. Is a hydrogen inlet hole of each of the separation plates 25 forming the hydrogen inlet passage 43a (in FIG. 3) of the fuel cell assembly 20 in which the fuel cell assembly 20 is stacked, and reference numeral 253b constitutes the oxygen inlet passage 43b. Oxygen inlet hole, reference numeral 253c denotes a coolant inlet hole forming the coolant inlet passage 43c.

Of course, in order to cool the fuel cell stack 1 in the coolant inlet passage 43c, coolant is introduced from the outside through the coolant supply port 42c of the end plate 12, and the end plate is inserted into the hydrogen inlet passage 43a. Hydrogen as a fuel gas flows in through the hydrogen supply port 42a of (12) from an external hydrogen tank 5 (Fig. 6).

In addition, reference numeral 251a denotes a hydrogen flow path of each of the separation plates 25 to which hydrogen is supplied from the hydrogen inlet passage 43a to each of the unit cells 22, and the back of the separation plate 25, which is not shown in FIG. An oxygen flow passage 251b (in FIG. 2B) having the same pattern is formed, and a cooling water flow passage 251c for circulating the cooling water is provided in the separating plate 25.

The present invention provides a coolant inlet passage 43c and a hydrogen inlet of a fuel cell assembly 20 in which coolant and hydrogen are supplied through corresponding supply ports of an end plate 12 to humidify hydrogen supplied to a fuel cell stack. The plurality of micropaths 257 are formed between the passages 43a.

That is, a small diameter between the cooling water inlet hole 253c of each separation plate 25 forming the cooling water inlet passage 43c and the hydrogen inlet hole 253a of each separation plate 25 forming the hydrogen inlet passage 43a. By forming a plurality of fine passages 257, the cooling water can be supplied and sprayed from the cooling water inlet hole 253c to the hydrogen inlet hole 253a.

Referring to the principle that the water is injected into the hydrogen inlet hole 253a through the micro passage 257 in each of the separation plates 25, the cooling water and hydrogen introduced into the cooling water inlet passage 43c and the hydrogen inlet passage 43a Is supplied at a certain pressure and flow rate for the smooth circulation, wherein if the pressure of the cooling water flowing through the cooling water inlet passage (43c) is greater than the pressure of hydrogen flowing through the hydrogen inlet passage (43a), each separation The cooling water flows from the cooling water inlet hole 253c to the hydrogen inlet hole 253a in the micro passage 257 of the plate 25.

At this time, since the flow rate of the flowing water through the hydrogen inlet passage 43a is fast in the cooling water flow rate in the micro passage 257, the hydrogen inlet hole 253a of each separation plate 25 is around the outlet of the micro passage 257. Negative pressure is formed.

As a result, the coolant may be sucked and injected into the hydrogen inlet hole 253a through the micro passage 257.

Hydrogen flowing through the hydrogen inlet passage 43a of the fuel cell assembly 20 may be humidified by the water injected as described above. In this case, the diameter of the microchannel 257 may be sufficient to allow cooling water to be sucked. It is obvious that the diameter should be a suitable diameter so that the amount of cooling water sucked is not excessively large.

In addition, in the preferred embodiment of the present invention, each of the separation plate 25, the drain hole 258 on one side of the lower portion of the hydrogen inlet hole 253a so that the water remaining after being humidified in the hydrogen inlet hole 253a can be drained. ) And a drain passage 259 connecting the drain hole 258 to a lower side of the hydrogen outlet hole 255a.

Here, the water drained through the drainage hole 258 is a hydrogen flow path 251a of each separation plate 25 through the drainage passage 259 by the pressure difference between the hydrogen inlet hole 253a and the hydrogen outlet hole 255a. ) Is moved to the hydrogen outlet hole (255a) is collected, the moved water is discharged to the outside with the hydrogen, or in the case of the fuel cell stack to circulate the hydrogen is introduced into the fuel cell stack again with hydrogen.

As described above, according to the hydrogen humidification structure of the fuel cell stack according to the present invention, in order to humidify the hydrogen supplied to the fuel cell stack, the cooling water inlet passage and the hydrogen inlet passage of the fuel cell cell assembly in which the unit cells are stacked. By forming a plurality of micropaths between the cooling water inlet hole and the hydrogen inlet hole of each separation plate forming a, an external humidifier is not required, thereby reducing the space and weight occupied by the humidifier, fuel cell stack It is also possible to reduce the cost required for configuration.

Claims (2)

Hydrogen, which is a fuel gas that is introduced from the outside through the hydrogen inlet passage 43a of the end plate 12 and the hydrogen inlet passage 43a of the fuel cell assembly 20 connected thereto and is supplied to each unit cell 22. In the hydrogen humidification structure of the fuel cell stack to humidify, In the separation plates 25 of the unit cells 22, the coolant inlet hole constituting the coolant inlet passage 43c of the fuel cell assembly 20 communicating with the coolant supply port 42c of the end plate 12 ( 253c and a plurality of micro passages 257 are formed between the hydrogen inlet holes 253a constituting the hydrogen inlet passage 43a, and the cooling water passing through the cooling water inlet passage 43c through the micro passage 257. The hydrogen humidifying structure of the fuel cell stack, characterized in that the intake and injection into the hydrogen inlet passage (43a). The method of claim 1, wherein each of the separating plate 25 to form a drain hole 258 on one side of the lower portion of the hydrogen inlet hole 253a so that the remaining water humidified and discharged from the hydrogen inlet hole 253a, The drain hole 258 is connected to the hydrogen discharge port 44a of the end plate 12, and the hydrogen outlet hole 255a of each separator plate 25 forming the hydrogen outlet passage 45a of the fuel cell assembly 20. ) Hydrogen humidifying structure of a fuel cell stack, characterized in that the drain passage 259 is connected to the lower one side.