JPS63155561A - Fuel cell - Google Patents

Abstract

PURPOSE:To uniformize a temperature distribution over the surface of a cell, by providing such an arrangement as positioning a cooling tube for a coolant inlet on the inlet side of an oxidizer passage and positioning a cooling tube for a coolant outlet on the outlet side of the oxidizer passage. CONSTITUTION:A cooling effect is excellent in the vicinity of the inlet of an oxidizer passage because a coolant inlet tube 13 supplied with a coolant at comparatively lower temperature than that of an inlet tube 11 is disposed there. In addition, a cooling outlet tube 14 supplied, from a return tube 15, with a coolant having comparatively high temperature due to heat exchange carried out at the cooling inlet tube 13, is disposed in the vicinity of the outlet of the oxidizer passage. Then, since the temperature in the vicinity of the outlet of the oxidizer passage is comparatively low, sufficient cooling performance can be satisfied even at the cooling outlet tube 14 through which coolant having comparatively high temperature flows. According to the abovementioned reason, any local high temperature on the flat face of a cell can be suppressed so as to maintain the temperature on the surface of the cell at a uniform level.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to cooling of fuel cells, and particularly relates to a fuel cell having a cooling plate that eliminates uneven temperature distribution on the cell surface. .

(Prior Art) Fuel cells are conventionally known as devices that directly convert energy contained in fuel into electrical energy. This fuel cell usually consists of a pair of porous electrodes sandwiching a matrix impregnated with an electrolyte, a fluid fuel such as hydrogen is brought into contact with the back of one electrode, and a fluid oxidant such as oxygen is brought into contact with the back of the other electrode. The system uses the electrochemical reaction that occurs at this time to extract electrical energy from between the electrodes, and as long as the fuel and oxidizer are supplied, electrical energy can be extracted with high efficiency. It is something that can be taken out.

FIG. 3 is a perspective view showing the configuration of a conventional unit cell.

In FIG. 3, the unit cell has an anode electrode 2 formed of a porous material with a catalyst coated on the surface in contact with the matrix 1 impregnated with an electrolyte, and a catalyst coated on the bottom surface in contact with the matrix 1, which is also porous. It is constructed by arranging a cathode ffH4i3 formed of a mass. In the anode electrode 2 and the cathode electrode 3, a fuel gas passage 4 through which fuel flows and an oxidant gas passage 5 through which oxidant gas flows are provided on opposite sides of the matrix 1, respectively, so as to be orthogonal to each other. Generally, in a phosphoric acid fuel cell, the fuel gas is hydrogen and the oxidant gas is oxygen in the air. In fuel cells, the voltage generated by a unit cell is as low as 1V or less, so 400 to 500 unit cells 6 are usually stacked together with heat-resistant and phosphoric acid-resistant separator plates 7 in between, as shown in FIG. 4, to generate a high voltage. This is how you get it. The above electrochemical reaction is.

Since this is an exothermic reaction, a cooling plate 9 is inserted for every several unit cells in the FI layer to prevent a rise in temperature, and the heat generated by the fuel cell is taken out to the outside.

As shown in FIG. 5, the cooling plate 9 is usually made of a compression-molded graphite resin composition, and a plurality of cooling pipes 10 each having a diameter of about 3IIE11 and subjected to insulation treatment are embedded therein at equal intervals. Water is usually used as a refrigerant, and is introduced through a cooling inlet pipe 11 and discharged through a refrigerant outlet pipe 12.

(Problems to be Solved by the Invention) By the way, the hydrogen contained in the fuel gas and the oxygen contained in the oxidizing gas are continuously caused by an electrochemical reaction occurring during the passage through the flow passages 4 and 5, respectively. consumed.

Therefore, hydrogen and oxygen partial pressures become high near the entrances of the flow passages 4 and 5, and decrease as they approach the exits of the flow passages 4 and 5. As a result, electrochemical reactions tend to occur near the inlets of the flow paths 4 and 5 where the partial pressure is high, and the current density distribution on the cell plane also tends to concentrate near the inlets of supplied hydrogen and oxygen. From this, the cell plane temperature also tends to be high near the supply hydrogen and W1 element inlets, and to become lower toward the outlet.

FIG. 6 is a graph showing the results of measurements of cell plane temperature distribution by the inventors. Under normal operating conditions,
At an operating temperature of 205°C, oxygen utilization rate UA = 60%, and hydrogen utilization rate of 80%, the temperature distribution along the oxygen flow path has a larger slope than the temperature distribution along the fuel flow path, and the temperature distribution near the V inlet and near the outlet This local high temperature, which currently has a temperature difference of about 10 to 15 degrees Celsius, is caused by fl! This affects the life of the electrodes, matrix, etc. that make up the battery, and also causes non-uniform reactions within the battery, resulting in a decrease in battery performance.

The present invention has been made in consideration of these points,
An object of the present invention is to provide a fuel cell equipped with a cooling plate that can keep the temperature of the electrode surface uniform.

[Structure of the invention]

(Means for solving the problem) In order to achieve the above object, a plurality of cooling pipes for introducing the refrigerant are embedded in the cooling plate, and the refrigerant inlet cooling pipe is located toward the entrance of the oxidizer flow path. , the refrigerant outlet cooling pipe is disposed toward the outlet of the oxidizer flow path.

(Function) With the above configuration, the vicinity of the oxidant flow path population is cooled by a cooling medium having a relatively low temperature, so that the cooling effect is excellent. On the other hand, the vicinity of the outlet of the oxidizer flow path is cooled by a high-temperature cooling medium, so the cooling effect is poor, but by doing so, it is uniformly cooled.

(Example) (composition) The present invention will be described below with reference to an embodiment shown in FIG.

In FIG. 1, a cooling inlet pipe 13 and a cooling outlet pipe 14 are embedded in the cooling plate 9, and the cooling medium is transferred from the artificial pipe 11 to the cooling inlet pipe 13, passes through the return pipe 15, and passes through the cooling outlet pipe 14. , and is configured to be discharged from the outlet pipe 12.

At this time, when embedding the cooling inlet pipe 13 and the cooling outlet pipe 14, they are arranged in a direction perpendicular to the oxidizing agent flow direction.

(Function) Next, the function of the cooling plate 9 of the fuel cell of the present invention implanted as described above will be explained. A cooling inlet pipe 13 to which a cooling medium having a relatively lower temperature than the inlet pipe 11 is supplied is arranged near the inlet of the oxidant flow path, so that the cooling effect is excellent.

On the other hand, near the outlet of the oxidizer flow path, a cooling outlet pipe 14 is arranged to which a relatively high temperature cooling medium, which has undergone heat exchange in the cooling manifold pipe 13, is supplied from a return pipe 15.

At this time, the temperature near the outlet of the oxidizing agent flow path is relatively low, so that even the cooling outlet pipe 14 through which a relatively high temperature cooling medium flows can sufficiently satisfy the cooling capacity. By improving the cooling effect near the oxidizing agent inlet in this way, it is possible to suppress local high temperatures on the battery plane, and it is possible to maintain a uniform battery plane temperature.

(Other examples) Next, another embodiment of the present invention will be described with reference to FIG.

In FIG. 2(a), a cooling inlet pipe 13 and a cooling outlet pipe 14 are embedded in the cooling plate 9, and the cooling medium is introduced from the inlet pipe 11 into the cooling inlet pipe 13, passes through the return pipe 15, and passes through the cooling outlet pipe 14. It is configured to be discharged from an outlet pipe 12. At this time, when burying the cooling inlet pipe 13 and the cooling outlet pipe 14, the cooling inlet 'EF13 and the cooling outlet pipe 14 should be oriented perpendicularly to the oxidizing agent flow direction, and the cooling inlet pipe 13 should be buried as it approaches the oxidizing agent inlet. .

The cooling inlet pipes 13 are arranged so that they are closely spaced from each other.

As a result, the surface area of the cooling pipe per unit area of the cooling plate 9 near the oxidizer inlet increases, so the cooling effect near the oxidizer inlet is further improved, and the same improvement in battery performance as in this example can be achieved. can.

A second alternative embodiment is shown in FIG. 2(b). Figure 2 (b
), a cooling inlet pipe 13 and a cooling outlet pipe 14 are embedded in the cooling plate 9, and the cooling medium is introduced from the inlet pipe 11 to the cooling inlet pipe 13, passes through a return pipe 15 provided in each individual cooling pipe, and is cooled. It is configured to pass through the outlet pipe 14 and be discharged from the outlet pipe 12.

As in this embodiment, the cooling effect is excellent near the cooling inlet pipe 13 where relatively low-temperature cooling medium is supplied. Since the return pipe is provided, non-uniformity in the flow rate of each cooling pipe is reduced, and a more uniform cooling effect can be obtained.

〔Effect of the invention〕

As explained above, the present invention has the following effects.

Only the cooling inlet pipe, which is the outgoing path for the cooling medium, is placed near the oxidizer flow path inlet to improve the cooling effect, so local high temperatures near the oxidizer inlet can be suppressed, and the temperature on the battery surface can be reduced. It is possible to make the distribution uniform, which has the effect of prolonging the life of the battery and improving battery performance.

[Brief explanation of the drawing]

FIG. 1 is a front view showing one embodiment of the cooling plate of the present invention, FIGS. 2(a) and (b) are top views showing other embodiments of the cooling plate of the present invention, and FIG. 3 is a unit 4 is a perspective view showing the structure of a fuel cell, FIG. 5 is a top view showing a conventional cooling plate, and FIG. 6 is a diagram showing the temperature distribution on the cell surface. (a) is a diagram schematically showing the flow of fuel and air on the surface of a unit cell, (b) is a diagram showing the temperature distribution in the fuel flow direction, and (c) is a diagram showing the temperature distribution in the air flow direction. FIG. 9...Cooling plate 11...Inlet pipe 12...
Outlet pipe 13...Cooling inlet pipe 14...Cooling outlet pipe 15...Return management agent Patent attorney Noriyoshi Chika Noriyuki Hirofumi Mitsumata Figure 1 Figure 2 (α) ll Figure 5/Ri Figure 2 Figure (b) Figure 6 (cL)

Claims (1)

[Claims] (1) A battery body made by stacking a plurality of unit cells each having a matrix for holding an electrolyte between a pair of gas diffusion electrodes having a fuel flow path through which fuel flows and an oxidizer flow path through which oxidant flows. , a manifold for supplying and discharging fuel and oxidant to and from the gas diffusion electrode, respectively, is arranged on the side surface of the cell body, and a cooling plate is inserted between the unit cells. Multiple cooling pipes for introducing refrigerant are embedded in the cooling plate, and the cooling pipes are arranged so that the refrigerant inlet cooling pipe is located at the entrance of the oxidizer flow path, and the refrigerant outlet cooling pipe is located at the exit of the oxidizer flow path. A fuel cell characterized by: