JPH09326266A - Heat radiator of battery for power storage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat radiator of a battery capable of performing continuous fine control and reducing the occupying area of a battery module. SOLUTION: A heat radiator is constituted with a heat pipe 20 having a gas reservoir 25 at the end part, in which fluid and non-condensable gas are sealed, a condensing part 24 of the heat pipe 20 is constituted with a plurality of branch pipes 24a, 24b, 24c connected in parallel, and by making the cross section area of one branch pipe small, the diffusion effect on the interface of the working fluid and the non-condensable gas is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipation device for a power storage battery such as a sodium-sulfur battery (NaS battery), and in particular, a heat pipe containing a non-condensable gas having a continuously variable heat dissipation capability is used. The present invention relates to a heat dissipation device for an electric power storage battery.

[0002]

2. Description of the Related Art Since the amount of electricity used varies greatly depending on the time of day or night and the season, it has been attempted to store electric power by using a sodium-sulfur battery or the like in order to level this load fluctuation. . This type of sodium-sulfur battery is used as a battery module by assembling NaS cells in an adiabatic container and used as a battery module. However, since it is a high-temperature battery that utilizes a chemical reaction, it is heated to a temperature of 300 ° C. or higher. Is needed. On the other hand, the higher the temperature, the greater the deterioration of the battery and the inability to maintain the original amount of electricity stored in a short time.
It is preferable to suppress the temperature to 350 ° C. or lower at the highest. That is, it is preferable that the temperature is kept at 300 to 330 ° C. before use.

Conventionally, in order to maintain the temperature of such a battery for storing electric power, heating using a heater or the like and heat dissipation (cooling) using a heat pipe have been used together.
It was adjusted to the range of 00 to 330 ° C. In a conventional battery for storing electric power, a heater is used to heat the battery to start it up to 300 ° C. or higher, and at the time of operation, the temperature of the battery is suppressed to 350 ° C. or lower by using a heat pipe. However, the conventional heat pipe does not have a function of adjusting the amount of heat radiation, and since the heat pipe carries a large amount of heat even with a small temperature difference, it may cause excessive heat radiation, and even during operation (during storage and discharge). It was necessary to activate the heater. For this reason, there has been proposed a heat pipe provided with an opening / closing valve, and the opening / closing valve is opened / closed to adjust the effective area of the radiation fins stepwise (for example, JP-A-63-175,355). (See the official gazette).

[0004]

However, the adjustment of the amount of heat radiation by the on-off valve requires an on-off valve in the first place, and requires a control device or the like in addition to this, which causes a problem of cost increase. Further, when the amount of heat radiation is adjusted by the on-off valve, some heat pipes become inoperable, which may cause temperature distribution in the battery module. Further, since the valve opening / closing control is performed, the control is stepwise (digital), and it is difficult to perform analog fine adjustment, and the valve may be opened / closed frequently to cause a so-called hunting phenomenon.

On the other hand, the power storage battery is used by arranging or stacking a number of battery modules in parallel, and its power storage capacity is evaluated per unit volume. Therefore, the volume occupied by the heat dissipation device is extremely important. It's a problem. The present invention has been made in view of such problems,
An object of the present invention is to provide a heat dissipation device for a power storage battery, which can continuously control the amount of heat dissipation without using a control device and can reduce the volume occupied by the battery module.

[0006]

In order to achieve the above object, a heat dissipation device for a power storage battery according to the present invention is a heat dissipation device attached to a power storage battery module, which is a working fluid and a non-condensable gas. In a heat dissipation device for an electric power storage battery including a heat pipe having a gas reservoir at the end of the condenser enclosed therein, the condenser of the heat pipe comprises a plurality of branch pipes connected in parallel. And

In the heat dissipation device for the power storage battery of the present invention,
Since the heat pipe is filled with the working fluid and the noncondensable gas, when the heat pipe is operated, the noncondensable gas is pushed to the end of the condensing section by the vapor flow in the pipe. Here, the non-condensable gas is governed by the environmental temperature, but the saturation pressure of the working fluid rises significantly in accordance with the rise in temperature. Therefore, when the temperature rises, the interface between the working fluid and the non-condensable gas increases. However, strictly speaking, although it has some diffusion effect, it moves to the condensation section side. Therefore, the position of this interface is near the minimum holding temperature (about 300 ° C. in the sodium-sulfur battery) on the condenser side of the evaporation part, and near the maximum holding temperature (330-350 ° C. in the sodium-sulfur battery), the condensation part and the gas. If the non-condensable gas is enclosed at the boundary position with the reservoir, the function as a heat pipe is suppressed at the temperature up to the minimum holding temperature. On the other hand, when the temperature becomes higher than this, the working fluid region moves to the condensation section side, so that the condensation section is substantially expanded and the amount of heat radiation increases. Then, when the maximum holding temperature is reached, the non-condensable gas is stored in the gas reservoir at the end of the condensing portion, so that the greatest heat dissipation effect is exhibited.

As described above, in the heat dissipation device for the electric power storage battery of the present invention, the substantial existence region of the working fluid can be made variable according to the battery temperature without providing a device such as an on-off valve. Not only the on-off valve but also the control device associated therewith can be omitted. Further, since the amount of heat radiation is automatically controlled according to the battery temperature, an electronic device such as a temperature sensor becomes unnecessary. Therefore, the heat radiation amount can be finely adjusted without the control becoming stepwise and without causing the hunting phenomenon. As a result, after being heated to a certain temperature or higher, the battery temperature can be controlled only by the heat pipe, and the running cost and the control equipment can be reduced. At the same time, since a control device or the like is unnecessary, the volume occupied by the battery module can be substantially reduced.

As described above, in the heat dissipation device for the power storage battery of the present invention, the heat pipe in which the working fluid and the noncondensable gas are enclosed is used, and the movement of the interface between the working fluid and the noncondensable gas is prevented. However, if the pipe diameter is large, diffusion easily occurs at the interface between the working fluid and the non-condensable gas.

However, in the heat radiator of the power storage battery of the present invention, since the condensing part of the heat pipe is composed of a plurality of branch pipes connected in parallel, as compared with the case of being constituted by one pipe, The diameter of one branch pipe is small and sufficient.
Therefore, the diffusion effect of the interface between the working fluid and the non-condensable gas can be suppressed, and a clear interface is provided, so that the controllability is improved.

In the heat dissipation device for the power storage battery of the present invention, the gas reservoir may be provided at each end of each branch pipe, but the gas reservoir is connected at the ends of the plurality of branch pipes. Is more preferable. This is because by making the gas reservoirs communicate with each other at the end of each branch pipe, even if the vapor from the evaporation part flows into each branch pipe in a biased manner, the position of the interface becomes the same in each branch pipe.

In the heat dissipating device for the power storage battery of the present invention, the condenser section is provided with heat dissipating means such as heat dissipating fins, but a plurality of branch pipes are attached to the heat dissipating means at substantially equal intervals. More preferable. Since the distance from the heat source of the condenser can be made uniform, the heat dissipation efficiency is improved.

In the heat dissipation device of the power storage battery of the present invention, it is preferable that the total sectional area of the plurality of branch pipes and the sectional area of the evaporation portion of the heat pipe are substantially equal. It is possible to secure the necessary and sufficient amount of heat transfer by making the flow passage cross-sectional areas of the evaporation section and the condensation section equal, and in addition, since this reduces the cross-sectional area of each branch pipe, it does not The diffusion effect at the interface with the condensable gas can be suppressed.

In the heat dissipation device of the power storage battery of the present invention, it is preferable that the evaporating portion of the heat pipe has a flat cross section. By making the evaporation section of the heat pipe into a flat tube shape, without making the flow passage cross-sectional area of the tube extremely small, and yet with a necessary and sufficient heat transfer area secured,
It is possible to reduce the thickness of the heat equalizing plate to which the evaporation portion of the heat pipe is attached. As a result, the volume and weight of the battery module can be reduced. At the same time, the number of heat pipes can be reduced, which is advantageous in terms of workability and manufacturing cost.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a front vertical cross-sectional view showing an embodiment of a heat dissipation device for a battery for electric power storage of the present invention, FIG.
(B) is a side view, and a plurality of cylindrical sodium-sulfur cells 2 are erected and housed in a module case 1 formed of a heat insulating material. In the present embodiment, for example, 25 vertical cells and 12 horizontal cells 2 are stored, but the present invention is not particularly limited.

At the bottom of the heat insulating module case 1,
A heat equalizing plate 3 having excellent thermal conductivity is attached, and an evaporating portion 22 of the heat pipe 20 extends along the longitudinal direction of the heat equalizing plate 3. The heat pipe 20 of the present embodiment is a vacuum tube in which a working fluid and a non-condensable gas are enclosed, and the working fluid is not particularly limited.
Depending on the temperature range to be controlled, water, aromatics such as naphthalene and biphenyl, therms (trade name, Nippon Steel Chemical)
And the like. The non-condensable gas is not particularly limited, but is preferably a gas having excellent stability and being hardly dissolved in the working fluid, and examples thereof include argon, xenon, and nitrogen.

The evaporating portion 22 of the heat pipe 20 is embedded in the heat equalizing plate 3 as described above, but the other end of the evaporating portion 22 stands up on the side surface of the module case 1 and is set at 3 here.
The branch pipes 24a, 24b, 24c of the book are connected in parallel to form a condensing part 24. In this embodiment, the evaporation unit 2
2 inside diameter 20mm, one branch pipe inside diameter 12
mm, and the total cross-sectional area of the three branch pipes 24a, 24b, 24c is set to be substantially equal to the cross-sectional area of the evaporation portion 22. In this way, by equalizing the flow passage cross-sectional areas of the evaporation section 22 and the condensation section 24, it is possible to secure a necessary and sufficient amount of heat transfer, and moreover, by doing so, the respective branch pipes 24a, 24b, 24c. Since the cross-sectional area of is small, the diffusion effect at the interface between the working fluid and the non-condensable gas can be suppressed.

These three branch pipes 24a, 24b, 24c
The condensing unit 24 made of is provided with a radiation fin 26 made of copper or aluminum having excellent heat conductivity or brass having excellent workability, and heat is radiated by natural air cooling. The branch pipes 24a, 24b, and 24c are arranged on the heat radiation fins 26 at substantially equal intervals, and the distance from the condenser 24 is shortened over the entire heat radiation fins, so that the heat radiation efficiency is improved.

Also, three branch pipes 24a, 24b, 24
The ends of c are communicated with each other, and a gas reservoir 25 for accumulating the non-condensable gas is provided. In this embodiment, the inner diameter of the heat pipe 20 is 20 mm, and the inner diameter of the branch pipe is 12 mm.
On the other hand, the inner diameter of the gas reservoir 25 is 40 mm.

When filling the heat pipe 20 with the working fluid and the non-condensable gas, the following points should be noted. That is, although details will be described later, in the present embodiment, the evaporation unit 2
By utilizing the movement of the interface between the working fluid and the non-condensable gas depending on the temperature of 2, the substantial lengths of the evaporation section 22 and the condensation section 24 are made variable, so that the position of this interface is Near the minimum holding temperature (about 300 ° C. for the sodium-sulfur battery), on the condenser 24 side of the evaporation unit 22, near the maximum holding temperature (330-350 ° C. for the sodium-sulfur battery), the condenser 24 and the gas reservoir 25. Enclose the non-condensable gas so that it becomes the boundary position with.

The heat pipe 20 described above is shown in FIG.
As shown in FIG. 2, two sets are provided in one module case 1. Next, the operation will be described. FIG. 3 is a perspective view for explaining the operation of the heat dissipation device for a power storage battery of the present invention, showing a heat pipe 20 in which a working fluid and a noncondensable gas are enclosed. When the heat pipe 20 operates, the non-condensable gas is pushed into the end of the condenser 24, that is, the gas reservoir 25 side by the vapor flow in the pipe.

Here, the non-condensable gas is governed by the ambient temperature, and the temperature dependence of the saturation pressure of the working fluid is significantly larger than that of the non-condensable gas. Strictly speaking, the interface with the non-condensable gas has a slight diffusion effect, but moves to the condensation section 24 side.

Therefore, the position of this interface is shown in FIG.
As shown in (A), in the vicinity of the minimum holding temperature of the sodium-sulfur battery of 300 ° C., the maximum holding temperature of 330 to 350 ° C. is located at the position A on the condensation unit 24 side of the evaporation unit 22.
In the vicinity, the non-condensable gas is filled so as to be at the boundary position B between the condenser 24 and the gas reservoir 25. As a result, the working fluid is pushed by the pressure of the non-condensable gas at the temperature up to the minimum holding temperature of 300 ° C.
Since it exists only in the soaking plate 3 part, the function as the heat pipe 20 is suppressed. On the other hand, when the temperature becomes higher than this, the pressure of the working fluid overcomes the pressure of the non-condensable gas, and the interface between the working fluid and the non-condensable gas moves to the condensation section 24 side, so that the condensation section 24 is substantially formed. Is gradually expanded as the temperature rises. As a result, the amount of heat dissipation increases in an analog manner, and the maximum holding temperature is 330 to 350 ° C.
When the temperature reaches, the non-condensable gas is stored in the gas reservoir 25 at the end of the condensing part 24, and therefore the greatest heat dissipation effect is exhibited.

Here, the evaporator 2 is heated by the heat from the battery 2.
The working fluid (vapor state) evaporated in 2 moves toward the condensing part 24 while pushing up the non-condensable gas, but the branch pipe 24
A, 24b and 24c are divided into three substantially equal parts to reach the respective branch pipes 24a, 24b and 24c. At this time, since the cross-sectional area of the branch pipe is sufficiently small, the diffusion effect at the interface between the working fluid and the non-condensable gas is suppressed, whereby the condensing portion 24 appears clearly and the controllability is improved.

Further, the working fluid is the branch pipes 24a, 24b,
When branching into each of the branch pipes 24c, even if they flow unevenly into any of the branch pipes, the upper ends of the branch pipes communicate with each other through the gas reservoir 25, so that the respective branch pipes 24a, 24b,
The interface position between the working fluid and the non-condensable gas at 24c has almost the same height as shown by C in FIG. 3, which also improves the heat dissipation controllability.

As described above, in the heat dissipation device for the power storage battery of the present embodiment, the amount of heat dissipation can be continuously varied, and therefore the control does not become stepwise and the hunting phenomenon does not occur. It is possible to finely adjust the heat radiation amount. As a result, after the battery is heated to a certain temperature or higher, the battery temperature can be controlled only by the heat pipe 20, so that the running cost and the number of control devices can be reduced.

Further, since the working fluid and the non-condensable gas itself sense the temperature of the battery and the amount of heat radiation is automatically controlled according to the battery temperature, an electronic device such as a temperature sensor becomes unnecessary. Further, in the heat dissipation device for the power storage battery of the present embodiment, the substantial region of the working fluid can be made variable according to the battery temperature without providing a device such as an on-off valve. Therefore, it is possible to omit the control device and the like accompanying this.

Further, the condenser 24 is connected to the branch pipes 24a, 24.
Since it is configured by b and 24c, the diffusion effect at the interface between the working fluid and the non-condensable gas is suppressed, and the heat dissipation controllability is improved. The present embodiment can be modified in various ways.
For example, FIG. 2 is a side view showing another embodiment of the heat dissipation device for a power storage battery of the present invention, which is different from the above embodiment in that the condensing part 24 is composed of two branch pipes 24a and 24b. The other configurations are the same except for the above. Even if the number of branch pipes is changed in this manner, the interface between the working fluid and the non-condensable gas in each branch pipe becomes clear and the heat dissipation controllability is improved, as in the above-described embodiment.

The present invention can be further modified. For example, in the embodiment shown in FIGS. 1 and 2, the evaporation portion 22 of the heat pipe 20 may be formed into a flat tube shape as shown in FIG. At this time, the evaporation unit 22 of the heat pipe 20
The other portions may or may not have a flat tube shape. As shown in FIG. 4, the ratio b / a of the minor axis b to the major axis a of the tube showing the degree of flatness is preferably about 0.5 to 0.3. If this ratio is too small, the flow path resistance becomes too large, which is not preferable, and this ratio is too large (1
Approaching), the flatness disappears and the effect of flattening becomes smaller.

As described above, the evaporating portion 22 of the heat pipe 20, which is a portion to which the heat from the battery module case 1 is transferred, has a flat tube shape, so that the flow passage cross-sectional area of the tube is not extremely reduced. Moreover, it is possible to reduce the thickness of the heat equalizing plate 3 to which the evaporating portion 22 of the heat pipe 20 is attached while ensuring a necessary and sufficient heat transfer area. As a result, the volume and weight of the battery module case 1 can be reduced. At the same time, the number of heat pipes 20 can be reduced, which is advantageous in terms of workability and manufacturing cost.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention.

[0032]

As described above, according to the heat dissipation device for the electric power storage battery of the present invention, the heat dissipation amount can be continuously varied by the heat pipe in which the working fluid and the noncondensable gas are enclosed. Since it is possible to change the substantial existence region of the working fluid according to the battery temperature without providing a device such as an on-off valve, not only the on-off valve but also the control device accompanying it can be used. It can be omitted. Further, since the amount of heat radiation is automatically controlled according to the battery temperature, an electronic device such as a temperature sensor becomes unnecessary. At the same time, since a control device and the like are unnecessary, the volume occupied by the battery module can be substantially reduced.

According to the heat dissipating device for a battery for electric power storage of the present invention, the condensing part of the heat pipe is composed of a plurality of branch pipes connected in parallel. Therefore, the diameter of one branch pipe can be thin. Therefore, the diffusion effect of the interface between the working fluid and the non-condensable gas can be suppressed, and a clear interface is provided, so that the controllability is improved.

In the present invention, a necessary and sufficient amount of heat transfer can be secured by making the flow passage cross-sectional areas of the evaporation portion and the condensation portion equal. Moreover, since the cross-sectional area of each branch pipe is reduced by doing so, the diffusion effect at the interface between the working fluid and the non-condensable gas can be suppressed.

In the present invention, the evaporation part of the heat pipe,
By evaporating the heat pipe without making the cross-sectional area of the flow path of the tube extremely small and ensuring a necessary and sufficient heat transfer area, by making the cross-sectional shape of the evaporation part of the heat pipe into a flat tube shape. It is possible to reduce the thickness of the heat equalizing plate, the heat radiating means, etc. to which the parts are attached. As a result, the volume and weight of the battery module can be reduced.
At the same time, the number of heat pipes can be reduced, which is advantageous in terms of workability and manufacturing cost.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of a heat dissipation device for a power storage battery of the present invention, (A) is a front vertical cross-sectional view,
(B) is a side view.

FIG. 2 is a side view showing another embodiment of the heat dissipation device of the power storage battery of the present invention.

FIG. 3 is a perspective view for explaining the operation of the heat dissipation device of the power storage battery of the present invention.

FIG. 4 is a cross-sectional view of a heat pipe showing another embodiment of the heat dissipation device for the power storage battery of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Module case 2 ... Single cell 3 ... Soaking plate 20 ... Noncondensable gas-containing heat pipe 22 ... Evaporating part 24 ... Condensing part 24a, 24b, 24c ... Branch pipe 25 ... Gas reservoir 26 ... Radiating fin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Sakaigawa 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Kenji Watanabe 4-1 Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Energy and Environmental Research Laboratory, Tokyo Electric Power Company

Claims (5)

[Claims] 1. A heat dissipation device attached to a power storage battery module, comprising a heat pipe having a working fluid and a non-condensable gas sealed therein and having a gas reservoir at an end of the condenser. In the heat dissipation device, the heat dissipation device of the power storage battery, wherein the condensing part of the heat pipe is composed of a plurality of branch pipes connected in parallel. 2. The heat dissipating device for a power storage battery according to claim 1, wherein the gas reservoirs are connected to each other at ends of the plurality of branch pipes. 3. The heat radiation of the battery for electric power storage according to claim 1, wherein the plurality of branch pipes are attached to the heat radiation means provided in the condenser at substantially equal intervals. apparatus. 4. The heat dissipation device for a power storage battery according to claim 1, wherein a total cross-sectional area of the plurality of branch pipes and a cross-sectional area of an evaporation portion of the heat pipe are substantially equal to each other. 5. The cross section of the evaporation part of the heat pipe comprises:
The heat dissipation device for a battery for electric power storage according to any one of claims 1 to 4, which has a flat tube shape.