JPH07105239B2 - Fuel cell cooling body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a cooling plate provided in a battery stack formed of a plurality of plate-shaped cells and a groove provided in the cooling plate. The present invention relates to a cooling body for a fuel cell, which includes a cooling pipe housed in the.

[Conventional technology]

A fuel cell is a battery in which a single cell consisting of a fuel electrode and an oxidizer electrode with an electrolyte layer sandwiched between them and plates with grooves for supplying the reaction gas to the fuel electrode and the oxidizer electrode are joined together. For example, in a phosphoric acid fuel cell, a laminated body is formed, and in the case of a phosphoric acid fuel cell, the electrolyte layer is a matrix layer impregnated with phosphoric acid, the pair of electrodes are each made of a material having gas diffusibility, and the fuel electrode is made to oxidize hydrogen as a fuel gas. Oxygen is supplied to the agent electrode as an oxidant gas, and electricity is generated by an electrochemical reaction in the unit cell inside the battery stack, but energy that is not used as electrical energy is generated as heat, so the battery stack The body must be cooled to maintain the operating temperature of the fuel cell. As this method, there are cooling by circulation of an electrolytic solution, cooling by gas, cooling by cooling water, etc. When the electrolytic solution is held in a matrix layer, a plurality of unit cells constituting a battery stack are stacked. Arrange a cooling plate with a cooling pipe for each
A method of passing cooling water as a cooling medium through the cooling pipe to cool the heat generated by the electrochemical reaction of the fuel cell to maintain the operating temperature is adopted. In this case, the cooling pipe disposed on the cooling plate is integrally formed with the cooling plate or is divided into two parts. Hereinafter, a conventional technique will be described with reference to the drawings.

FIG. 3 is an exploded perspective view showing an example of a cell stack of a phosphoric acid fuel cell according to the prior art. In FIG. 3, reference numeral 1 is a matrix layer, and the matrix layer is sandwiched between the fuel electrode 2 and the matrix layer.
And the oxidizer electrode 3 are arranged, and the fuel electrode 2 is provided with a gas-diffusible ribbed electrode base material 2b having a groove 2a for passing the fuel gas, and the oxidizer electrode 3 is provided orthogonal to the groove 2a. A gas-diffusible ribbed electrode base material 3b having grooves 3a is in close contact with the ribbed electrode base materials 2b and 3b, and a separate plate 4 is interposed to form a unit battery. A plurality of these unit batteries are provided via a separate plate 4. The cooling pipe 6 branched from the inlet cooling pipe header 6a penetrates the cooling plate 5 and is connected to the outlet cooling pipe header 6b.

FIG. 4 is a partial perspective view showing the structure of a conventional cooling plate. The cooling pipe 6 arranged in the groove 5a of the cooling plate 5 is embedded in the groove 5a by a filler 5b made of a mixture of carbon and heat resistant resin. Has been.

[Problems to be Solved by the Invention]

Now, in order to operate the fuel cell, the reaction gas consisting of fuel gas and air is supplied to the electrodes through the grooves 2a and 3a of the ribbed electrode substrate, respectively, and an electrochemical reaction is caused in the unit cell to generate electric energy. However, the heat generated without being used for electric energy is removed by the cooling water flowing from the cooling water supply source (not shown) to the cooling pipe 6 via the inlet cooling pipe header 6a, and this cooling water is discharged to the outlet cooling pipe header. Emitted from 6b. However, conventionally, the cooling plate is made of a carbon material having a coefficient of thermal expansion substantially equal to that of the electrode constituting the cell constituent material, the electrode base material with ribs, and the separate plate, and damage due to the generation of thermal stress due to the difference in thermal expansion due to a high operating temperature is prevented. To prevent. Therefore, for the arrangement of the cooling pipes on the cooling plate, it is conceivable to integrally form expanded graphite having an expansion coefficient substantially equal to that of the former (see JP-A-57-162273). This expanded graphite has a small thermal conductivity in the pressing direction of 3 to 5 kcal / mh ° C and is not a good method considering the cooling performance of the fuel cell.

Even when the cooling plate is divided into two to form a groove on the mating surface of the cooling plate and the cooling pipe is fitted into the groove and tightened to form the cooling plate, the contact thermal resistance between the cooling pipe and the cooling plate is reduced. It has the drawback of becoming large.

In addition, in order to fit the cooling pipe into the cooling plate, it is necessary to severely limit the processing margin of the groove size of the cooling plate and the outer dimension of the cooling pipe, which is also a problem from the viewpoint of processing cost. .

In view of the above points, the present invention favorably conducts heat between the cooling pipe and the cooling plate arranged in the cooling body, and reduces the electrical contact resistance between the two cooling plates. An object is to provide a cooling body for a fuel cell at low cost.

[Means for Solving the Problems]

According to the present invention, in order to solve the above-mentioned problems, a battery stack formed of a plurality of plate-shaped unit cells is interposed, and
A cooling body for a fuel cell, comprising a cooling plate formed by stacking a plurality of carbon plates, and cooling pipes housed in grooves provided on the respective mating surface sides of the cooling plates. The expanded graphite sheets sandwiched between the layers tightly bond the cooling plate and the cooling pipe and the mating surfaces of the two cooling plates. Further, instead of the expanded graphite sheet, a sheet made of carbon powder and a binder may be used.

[Action]

According to the configuration of the present invention, the cooling plate which is interposed in the battery laminated body formed of a plurality of plate-shaped unit cells and is composed of the upper and lower two carbon plates, and the inner surface of each of the cooling plates is provided. In a cooling body for a fuel cell comprising a cooling pipe housed in a groove, an expansive graphite sheet is provided in the groove provided on the mating surface side of each of the two cooling plates and on the entire mating surface between the cooling plates. In the groove, a cooling pipe is sandwiched between the expanded graphite sheets, and the battery stack is tightened in the stacking direction. Therefore, a compressive force is applied to the cooling plate, and the compression elastic force of the expanded graphite sheet causes the cooling plate to cool. The dimensional error between the cooling pipe and the cooling pipe is absorbed, and a close fit can be made, resulting in good heat conduction. Also, 2
Since the expanded graphite sheet having elasticity is interposed over the entire width of the mating surfaces of the cooling plates, the electrical contact resistance between the two cooling plates is reduced. Expanded graphite has a smaller electric conductivity than a cooling plate, but since it is a thin sheet, an increase in electric resistance does not pose a problem, and a reduction in contact resistance reduces electric resistance as a whole. Similar effects can be obtained by using a sheet made of carbon powder and a binder instead of the expanded graphite sheet. From the viewpoint of electrical contact resistance, a sheet made of elastic carbon powder and a binder is superior to the expanded graphite sheet. Furthermore, since the cooling pipe is clamped around its periphery by a sheet made of carbon powder and a binder as described above, the compression elastic force of the sheet causes a dimensional error between the cooling plate groove and the cooling pipe. Can be absorbed to create a close fit.

[Examples] The present invention will be described below based on Examples. FIG. 1 is a cross-sectional view of a cooling plate and a cooling pipe showing an embodiment of the present invention. Cooling plates 7 and 8 formed of carbon material in two upper and lower layers are provided with a plurality of rows of grooves 7a and 8a. The cooling pipe 9 is housed therein.
The expanded graphite sheet 10 is sandwiched in common between the mating surfaces of the cooling plates 7 and 8 and the mating surfaces of the grooves 7a and 8a of the cooling plates and the cooling pipe 9, and the space between the cooling plates 7 and 8 and the grooves 7a and 8a. And the gap between the cooling pipe 9 and the cooling pipe 9 is filled. As the expanded graphite sheet 10, for example, a graph oil sheet used as a packing material or the like is used, and it is an extremely thin sheet capable of compensating for processing errors of the cooling plates 7 and 8 and their grooves 7a and 8a and the cooling pipe 9. May be used. The cooling plate integrally formed as described above is held in the fuel cell by the stacking fastening united with the cell stack. Since the expanded graphite sheet 10 is harder and more difficult to bend than a sheet made of carbon powder and a binder, it is used by being formed in advance along the curves of the grooves 7a and 8a.

Next, an embodiment of the present invention using a sheet made of carbon powder and a binder will be described with reference to an exploded perspective view shown in FIG.

A sheet made of carbon powder and a binder has a structure in which carbon black is bound with a fluororesin such as polytetrafluoroethylene (abbreviated as PTFE). It is manufactured by mixing and dispersing to make a paste, kneading, and rolling with a calendar roll or the like. When kneading, the PTFE particles are made into fibers and entangled with carbon black, which makes it possible to manufacture a sheet that is excellent in mechanical strength and thermal conductivity while being easy to bend. As shown in the perspective view of FIG. 2, the sheet 11 is inserted between the cooling plates 7 and 8 and the cooling pipes 9 and pressure-tightened so as to be sandwiched between the cooling plates 7 and 8 and the cooling pipes 9. Fill the gap,
The heat conduction is made good, and the gap formed by the difference in thermal expansion between the cooling plates 7 and 8 and the cooling pipe 9 can be absorbed by the elasticity of the sheet 11. After filling sheet 11 like this,
By heating at a temperature of 0 ° C or higher and further applying pressure to bond the cooling plates 7 and 8 and the cooling pipes 9 by firing and bonding, it is possible to further improve the heat conduction and also the electric conduction, and further cooling. The tube 9 and the cooling plates 7 and 8 are integrated to facilitate handling during assembly of the fuel cell.

In the example using the sheet made of the carbon powder and the binder and the example using the expanded graphite sheet described above, only the material of the sheet is different, and the cross sections applied to the cooling body and the cooling pipe are both the first It has the shape shown in the figure.

〔The invention's effect〕

As described above, the present invention provides a cooling body for a fuel cell including a cooling plate made of a carbon plate interposed in a cell stack and a cooling pipe housed in a groove provided in the cooling plate,
A sheet of carbon powder and a binder or an expanded graphite sheet is sandwiched between two side-by-side cooling plates and a cooling pipe so that the sheet is made of carbon powder and a binder. Since the cooling body structure having high electric conductivity can be obtained, it is not necessary to severely limit the working margin of the cooling plate and the cooling pipe, and the working cost can be reduced. In addition, by filling the expanded graphite material between the groove of the cooling plate and the outer periphery of the cooling pipe, which is a conventional technique,
Compared with the method of assembling after compression, there is an effect that the assembling process is simpler and the assembling process can be reduced, and the heat conductive property is excellent and the cooling body can be provided at a low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of a cooling plate and a cooling pipe including an expanded graphite sheet according to an embodiment of the present invention, and FIG. 2 is a perspective view illustrating an assembled state using a sheet made of carbon powder and a binder. FIG. 3 is an exploded perspective view showing an example of a cell stack of a phosphoric acid fuel cell according to the prior art, and FIG. 4 is a sectional perspective view of a cooling plate and a cooling pipe according to the conventional example. 7,8 ... Cooling plate, 7a, 8a ... Groove, 9 ... Cooling tube, 10 ... Expanded graphite sheet, 11 ... Sheet made of carbon powder and binder.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Ujiie 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (72) Inventor Atsushi Oyama 1 Tanabe-taden, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 in Fuji Electric Co., Ltd. (72) Inventor Yoshiharu Kobayashi No. 1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 Fuji Electric Co., Ltd. (72) Takashi Harada 1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 in Fuji Electric Co., Ltd. (72) Inventor Kaoru Kondo No. 1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 in Fuji Electric Co., Ltd. (56) Reference JP-A-57-162273 (JP, A) Kai 61-22573 (JP, A) JP 63-24562 (JP, A)

Claims (2)

[Claims] 1. A cooling plate, which is interposed in a battery stack formed of a plurality of plate-shaped unit cells and is formed by stacking two carbon plates, and each cooling plate is provided on a mating surface side. In a cooling body of a fuel cell including a cooling pipe housed in a groove, an expanded graphite sheet sandwiched between layers of the two cooling plates is provided between the cooling plate and the cooling pipe and between the two cooling plates. A cooling body for a fuel cell, characterized in that the mating surfaces of are joined together. 2. A cooling plate, which is interposed in a battery stack formed of a plurality of plate-shaped cells and is formed by stacking two carbon plates, and each cooling plate is provided on a mating surface side. In a cooling body of a fuel cell including a cooling pipe housed in a groove, a sheet made of carbon powder and a binder sandwiched between layers of the two cooling plates is used to connect the cooling plate and the cooling pipe. A cooling body for a fuel cell, characterized in that a space and a mating surface of two cooling plates are closely joined.