JPS63241875A - Fuel cell laminated body - Google Patents

Abstract

PURPOSE:To make it possible to remove more heat without increasing flow of coolant by forming passages for coolant linearly and disposing part of heat pipes embedded in cooling plates facing or close to the coolant passages. CONSTITUTION:Fuel gas is led through a manifold 13a to a fuel cell laminated body 11, and oxidizer gas is led through a manifold 13c, so electrochemical reaction occurs in a gas diffusion electrode, and electric energy is produced. Both gases P, Q are discharged through manifolds 13b, 13d. For cooling plates 14a-14e, coolant C flows in opposite directions in adjacent cooling plates as shown by arrows. Temperature distribution in cooling plates 14a-14e on the side of supply pipes 16a-16e and on the side of discharge pipes 17a-17e is also opposite to each other in adjacent cooling plates. The heat inside the laminated body 11 is transferred to the cooling plates 14a-14e. A heat pipe 19 crossing a linear passage 18 removes heat of cooling plates 14a-14e by a heat exchange, and temperature distribution in cooling plates 14a-14e becomes uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a fuel cell stack in which a cooling plate is interposed between unit cells.

(Prior technology) In fuel cells such as molten carbonate type and phosphoric acid type, the electromotive force obtained by each unit cell is low, so to configure a high output power generation plant, multiple unit cells must be connected in series. They must be stacked to form a fuel cell stack so as to obtain the summed output of each unit cell. FIG. 7 shows a molten carbonate type fuel cell stack 1.

Each unit cell 2 is composed of a pair of porous 1ffi plates, that is, a 7-node HA Fi 3 a, a cathode electrode 3b, and an electrolyte layer 4 made of an alkali carbonate interposed between them. These unit batteries 2 are stacked with separators 5 in between. The separator 5 has both the function of electrical connection between each unit cell and the function of forming a passage 6 for reaction gas to each electrode plate.

On the four sides of the fuel N battery stack 1, there is a distribution of reactive gas,
A not-shown manifold having a collection function is applied. Then, oxidant gas Q is supplied to one of these manifolds, and fuel gas P is supplied to the adjacent manifold to cause a reaction of H2+CO32-+H20+CO2+2e- at the anode electrode 3a and 1/1 at the cathode electrode 3b. 202
After a reaction of +CO2+2B--)COa2- is generated and a DC output is obtained, the gas is discharged from each opposing manifold.

Incidentally, the fuel cell stack 1 generates heat as well as electric power through the above chemical reaction. If this heat is not removed, the operating temperature range of molten carbonate fuel cells is 600-700°C.
℃, making it impossible to promote an effective electrode reaction. However, since the four sides of the fuel cell stack 1 are covered with manifolds, the heat removal ability is low.

Therefore, conventionally, the inside of the fuel cell stack 1 was cooled by using the oxidizing gas Q as a coolant and circulating the oxidizing gas Q inside the fuel cell stack 1 in excess.

However, in this method, the oxidant gas must be supplied in excess of the amount that contributes to the electrode reaction, which not only reduces the efficiency of the entire system, but also causes the oxidant gas flow rate to be much larger than that of the fuel. In order to distribute to
A large pressure difference occurs between the cathode side and the anode side of the unit cell 2, and the oxidant moves in the electrolyte and leaks to the fuel gas side, causing cross-mixing of the fuel gas and oxidant gas, resulting in a decrease in efficiency. There was also the problem that it caused

Therefore, conventionally, in phosphoric acid type air-cooled fuel cell stacks, etc., cold W plates are stacked at intervals of about one per several cells, and air is pumped from a specific side of the fuel cell stack to this cooling plate. coolant at a temperature slightly lower than the battery temperature,
Measures have been taken to remove heat by heat transfer.

Examples of such means include, for example, a cooling plate 7 with tubular passages 8 as shown in FIG.
As shown in the figure, there is one in which a manifold-shaped passage 10 is formed in a cooling plate 9.

However, in such a method, since the coolant is forced to flow over the entire cooling plate 7.9, the passage is bent, and a considerable amount of electric power is required to send the coolant. Heat transfer also increases in proportion to the flow rate or flow rate of the coolant, so
In order to remove a lot of heat, a large flow rate is required, which increases costs.

(Problems to be Solved by the Invention) As described above, in the conventional structure in which cooling plates are laminated in place of excessive supply of oxidant gas, the coolant passage is bent, and a large amount of electric power is required to send the coolant. In addition, a large flow rate was required to remove a large amount of heat, which increased costs.

Therefore, the present invention provides a fuel cell stack that can remove a large amount of heat without increasing the flow rate of the coolant, and can reduce the power cost for sending the coolant.

[Structure of the Invention] (Means for Solving the Problem) The present invention is constructed by stacking unit batteries and a cooling plate that cools the unit batteries by circulating a coolant through an internal coolant passage. In the fuel cell stack, the coolant passage is formed in a straight line, a plurality of heat pipes are embedded in the cooling plate, and some of the heat pipes are arranged so as to face or be close to the coolant passage. did.

<Function> According to the present invention, since the passage inside the cooling plate stacked on the unit battery is substantially straight, the flow passage resistance is reduced and the wasted power for feeding the coolant can be reduced.

In the vicinity of the coolant passage, direct heat exchange occurs between the cooling plate and the coolant, and in the heat pipe, heat exchange between the cooling plate causes the internal refrigerant to evaporate, and the evaporated refrigerant is A cycle is formed in which the heat vibrator moves to the passage side and condenses and liquefies through heat exchange with the coolant, so that the temperature of the cooling plate can be made substantially uniform throughout.

(Example) An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a perspective view showing a schematic configuration of a molten carbonate fuel cell to which an embodiment of the present invention is applied, and 11 is a pair of ridges having a rectangular shape and facing diagonally on the sides. 12a
, 12b are formed slightly flat.

A pair of opposing side surfaces of this fuel cell stack 11 are provided with manifolds 13a and 13t+ for supplying and discharging fuel gas P.
is applied, and manifolds 13C and 13d for supplying and discharging the oxidizing gas Q are applied to the other opposing side.

As shown in FIG. 2, the fuel cell stack 11 has, for example, 5
Unit battery stack blocks 158 to 15d are arranged between cooling plates 148 to 14e, respectively. Each of the unit battery vllfd blocks 158 to 15d is a stack of, for example, five unit batteries, and its structure is the same as that shown in FIG. 7 described above.

As shown in FIG. 3, the cooling plates 14a to 14C1 are provided with coolant supply pipes 16a to 16fli on one side of flat ridges 12a and 12b, and coolant discharge pipes 17a to 17e on the other side. Both these tubes are connected to the cooling plate 14a~
14fl+ is connected via a linear coolant passage 18 formed inside the 14fl+.

A plurality of heat pipes 19 are embedded inside the cooling plates 148 to 14e, and the heat pipes 19 are arranged perpendicularly to the coolant passage 18.
8 to 14e are distributed over the entire surface direction. The part of the heat pipe block 19 that is perpendicular to the coolant passage 18 is such that the heat pipe 19 passes through the coolant passage 18 and a part thereof faces the coolant passage 18 , so that the heat pipe 19 passes through the coolant passage 18 and a part thereof faces the coolant passage 18 . The flowing coolant C comes into direct contact with a portion of the heat pipe 19. Note that the heat pipe 19 may be one that does not penetrate the coolant 18 but has a portion close to the coolant passage 18, as long as it can exchange heat with the coolant C inside.

The coolant supply pipes 16a to 16e and the coolant discharge pipes 17a to 17e of the cooling plates 14a to 14e are alternately arranged adjacent to each other.

In the fuel cell configured in this way, when the fuel gas P is guided to the fuel cell stack 11 via the manifold 13a, and the oxidizing gas Q is guided via the manifold 13C,
The aforementioned electrochemical reaction occurs at the gas diffusion electrode, generating electrical energy. 1! Both gases P and Q subjected to the stock reaction are supplied to opposing manifolds 13b,
13d. At this time, heat is generated inside the fuel cell stack 11 as a result of the electrode reaction.

On the other hand, a coolant C such as air flows through the cold W plates 14a to 14e in opposite directions between adjacent cooling plates, as shown by arrows in the figure. Cooling plate 14a adjacent to coolant C
When the direction is reversed between
The temperature distribution of the cooling plates 4e is reversed between the adjacent cooling plates 18 to 14e, and the temperature distribution in the flow direction of the coolant C can be reduced by interaction. The heat generated inside the fuel cell stack 11 is transferred to the cooling plates 14a to 14e.

In this case, the coolant C in the coolant passage 18 and the cooling plate 14.
Direct heat exchange between the coolant passages 18 and 14e
Since this is linear, the cooling is performed mainly in a straight line around the passage 18, and if the passage 18 is used only, the temperature distribution of the cooling plates 148 to 14e becomes non-uniform in the direction perpendicular to the passage 78. However, in the heat pipe 19, the cooling plates 14a to 14e
The internal refrigerant evaporates due to heat exchange between the cooling plate 14 and
The evaporated refrigerant removes heat from a to 14e, moves toward the passage 18, loses heat through heat exchange with the refrigerant C, condenses into liquid, and moves away from the passage 18 via the capillary again. do. In this way, due to the cycle of the heat pipe 19, each of the cooling plates 14a to 14e has a substantially uniform temperature distribution even in the direction perpendicular to the passage 18.

In this way, even though the coolant passage 18 is linear, the temperature distribution of each of the cooling plates 148 to 14e is approximately uniform over the entire surface direction, and the wasted power for sending the coolant C can be reduced.

In addition, by using the heat pipe 19, the temperature distribution is made uniform, so a large amount of heat can be removed without increasing the coolant flow rate, and the structure is simple and economical. do.

Further, since the temperature distribution of each of the cooling plates 14a to 14e is made uniform, the thermal stress acting on the electrolyte plate of the unit cell is reduced, which leads to an improvement in the performance of the unit cell and, by extension, the fuel cell stack.

FIG. 4 shows another embodiment. This is the cooling plate 14a~
Coolant passages 18a and 13b are provided in parallel to both edges of 14e, coolant supply ports 20a to 2od, and coolant discharge port 21a.
~21d, 22a~22 (1, 23a ~23
d was installed with a difference of 1800. In this case, even between the adjacent cooling plates 14a to 14e, the coolant flows in the corresponding upper and lower passages are in opposite directions.

In this case, in addition to the same effects as in the above embodiment, the cooling plates 14a on the inlet side and the outlet side of the coolant C
The temperature difference between 14e and 14e can be reduced.

Note that this invention is not limited to molten carbonate fuel cells;
It is also applicable to phosphoric acid type fuel cell stacks.

[Effects of the Invention] As is clear from the above, according to the configuration of the present invention, the temperature distribution of the cooling plate can be made approximately uniform, and since the coolant passage is linear, the power for sending the coolant can be reduced. It never increases. Also, more heat can be removed without increasing the coolant flow rate.

Ru. Therefore, it becomes possible to reduce the power cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a schematic configuration of a molten carbonate fuel cell according to an embodiment of the present invention, FIG. 2 is a perspective view showing a fuel cell stack of the fuel cell, and FIG. FIG. 4 is a plan view of a cooling plate according to one embodiment, FIG. 4 is a plan view of a cooling plate showing another embodiment, FIGS. 5 and 6 are plan views of a conventional cooling plate, and FIG. 7 is a plan view of a fuel cell. It is an exploded perspective view showing a typical composition of a layered product. 11...Fuel cell stacks 148-14e...Cooling plates 15a-15d...Unit cell stacks 16a-16d, 20a-20d, 22a-
22d... Coolant supply pipes 17a to 17e, 21a to 21d, 23a to
23d... Coolant discharge pipe

Claims (1)

[Claims] In a fuel cell stack constituted by stacking unit cells and a cooling plate that cools the unit cells by circulating a coolant through an internal coolant passage, the coolant passage is formed in a straight line, and the A fuel cell stack, characterized in that a plurality of heat pipes are embedded in a cooling plate, and a part of the heat pipes is arranged so as to face or be close to the coolant passage.