JPH01234792A - Heat accumulating device - Google Patents

Abstract

PURPOSE:To make a device compact and to reliably prevent a latent heat accumulating material from being brought into an overcooling state without consuming surplus energy, by a method wherein a part containing a connection part between a branch pipe and a container is formed by a material having thermal conductivity lower than that of the container, and the other part is formed by a material thermal conductivity higher than that of the container. CONSTITUTION:With a switch 6 turned ON, a heater 5 is charged with a current, a metallic container 2 is heated, and heat is accumulated in a heat accumulating material 4. In this case, the heat of the heater 5 is transferred to a branch pipe 8 through the container 2, but since the root part of the branch pipe 8 is a low thermal conductivity material part 9, a quantity of heat transferred to the branch pipe 8 is extremely low. A high thermal conductivity material part 10 is located to the forward part of the low thermal conductivity material part 9, and besides since a radiation fin 11 is mounted, heat possessed by a heat accumulating material 4 in the branch pipe 8 is rapidly dissipated in the surrounding air. As noted above, an amount of heat flowing out to the surrounding air can be set to a high value as an out of heat coming in the branch pipe 8 is suppressed. When, after completion of heat accumulation, the heat accumulating material 4 is cooled to take out heat, the heat accumulating material 4 can be reliably prevented from being brought into an overcooling state.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention relates to a heat storage device using a latent heat storage material that exhibits a supercooled state at a temperature lower than a phase change temperature, and particularly relates to a heat storage device that uses a latent heat storage material that exhibits a supercooled state at a temperature lower than a phase change temperature. Concerning means to prevent.

(Prior Art) Heat storage materials used in heat storage devices that store thermal energy and take out heat as needed include sequential heat storage materials and latent heat storage materials. Since the latter has a heat storage density 3 to 5 times that of the former, it has the advantage of making the heat storage device more compact.

As an example of latent heat storage materials, there are many materials, such as sodium acetate-based hydrated salts, which do not solidify at temperatures lower than the phase change temperature and cause a supercooled state.

However, not only is the supercooled state unstable, but repeated supercooling causes a decrease in the phase component M of the heat storage material, and thus in the amount of latent heat.

Therefore, conventionally, such latent heat storage materials store heat while being kept in a molten state by heat insulation, and when necessary, they are cooled to change into a solid state to extract thermal energy.
It is generally used in a form that does not utilize supercooling.

In this case, conventionally, as shown in FIG. 2, a thin branch pipe 22 containing a heat storage material 23 is communicated with a heat storage tank 21, and this is naturally cooled by the air around the branch pipe 22, or a forced cooling mechanism is used. A method has been adopted in which a portion 23a of the heat storage material 23 in the branch pipe 22 is kept in a solid state (solid phase) by placing the heat storage material 23 in the branch pipe 22 and cooling it.

However, when a natural cooling method using the air around the branch pipe 22 is adopted, the heat storage material 23a in the branch pipe 22 melts, and the heat storage material 23 in the heat storage tank 21 is prevented from becoming supercooled. You will not be able to obtain any preventive effects. When we investigated the cause of this, we found that the heat storage was attached to the container wall of the heat storage tank 21.
In the case of using a tank, since the thermal resistance between the container wall and the branch pipe 22 is small, the temperature of the container wall and the branch pipe 22 becomes almost equal, and eventually the heat storage material 23 in the heat storage tank 21 is melted. It has been found that when the heater input is increased, the heat storage material 23a in the branch pipe 22 also melts at the same time.

In other words, in the natural cooling system, the amount of heat flowing from the branch pipe to the heat storage material inside the branch pipe is considerably greater than the amount of heat released from the heat storage material to the surrounding air. One possible method to improve this is to increase the surface area of the branch pipe, but this method results in an increase in the size of the branch pipe and is not practical.

On the other hand, when the heat storage material in the heat storage tank is heated from the inside through a heat exchanger, etc., the heat storage material in the heat storage tank reaches a supercooled state, but this is also due to heat transfer between the branch pipes and the heat storage material in the heat storage tank. This is because the resistance is much smaller than the thermal resistance between the heat storage material in the heat storage tank and the heat storage material in the branch pipes.

From these facts, not only when heat is stored by external heating, but also when heat is stored through a heat exchanger, etc., the thermal resistance of the branch pipes is small, so simply connecting the branch pipes to the heat storage container will ensure that a supercooled state is not reached. cannot be prevented.

Furthermore, although the method of cooling branch pipes by installing a forced cooling mechanism is highly reliable in terms of preventing overcooling, it is not necessarily preferable in terms of securing installation space and consuming energy.

(Problem to be Solved by the Invention) In this type of heat storage device that does not utilize supercooling of the latent heat storage material, conventional supercooling prevention means such as natural cooling or forced cooling of the branch pipes cannot reach the supercooled state of the heat storage material. There was a problem that it could not be reliably prevented.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat storage device that is compact and can reliably prevent a latent heat storage material from reaching a supercooled state without consuming excess energy.

[Structure of the Invention] (Means for Solving the Problems) The present invention comprises a container filled with a latent heat storage material that exhibits a supercooled state at a temperature lower than the phase change temperature, and a heat insulating layer provided around the container. In a heat storage device comprising a heat storage tank and a branch pipe which is provided in communication with the container of the heat storage tank and whose inside is filled with the heat storage material continuously with the M heat material in the container, the container of the branch pipe and A portion including the connecting portion of the container is formed of a material having a lower thermal conductivity than that of the container, and a portion of the pond is formed of a material having a higher thermal conductivity than that of the container.

In this case, it is desirable to provide radiation fins in portions of the branch pipes with high thermal conductivity.

<Function> Generally, when two members having different thermal conductivities come into contact, the thermal conductivity of the interface is given as the harmonic average of these thermal conductivities.

In other words, the amount of heat Q (k caj
/h) is here, TA, Ta: distance j (
n+) Temperature of heated members A and B (°C) λ, λB Thermal conductivity of two members A and B (k CafJ/ff1h″C) S: Area of interface (rr+′) It is given by:

As is clear from this equation, reducing the thermal conductivity of one member leads to reducing the amount of heat passing through the interface.

Next, if we consider the thermal conductivity of various parts and the thermal conductivity of heat storage materials, it is 13 to 100 k for general metals.
caJ /11h'c, plastics etc. are 0
．． 1 to 0.3 kcaJl/n+h'c.

In contrast, the thermal conductivity of a heat storage material exhibiting supercooling is 0.3
~0.6 kcaJ/lh'c, and when the thermal conductivity of the interface is calculated based on these values, it is approximately as follows.

(1) For metal-metal, 13kcaj /lh'c
(2) Heat storage material - metal: 0.8 kcaj/nh
'c (3) For heat storage material-plastic, 0.16kCaj/11h'C (4) For metal-glass, (l19kcaj/l
′! +h'C (5) Heat storage material - 0.4 kc for heat storage material
aj/lh'c Based on these facts, by changing the material of the branch pipe to a material with a lower thermal conductivity than the heat storage container (metal), such as plastic, the thermal conductivity (=thermal resistance) can be reduced by approximately 1/1. It can be reduced to 68 (0,19÷13).

Additionally, in general, the lower the thermal conductivity, the higher the specific heat, and the less likely the temperature will rise.

Here, the material with low thermal conductivity is the base of the branch pipe,
In other words, it is only necessary to apply it to the connection part with the heat storage container where heat is transmitted, and if the other parts are made of a material with high thermal conductivity and the heat is dissipated to the surrounding air, the heat storage material in the branch pipes will melt. Never.

(Example) The present invention will be explained in detail below.

FIG. 1 is a sectional view showing the configuration of a heat storage device according to an embodiment of the present invention. In the figure, the heat storage tank 1 is a metal container 2 that is surrounded by a heat insulating layer 3, and the container 2 contains, for example, sodium acetate hydrate in a supercooled state at a temperature lower than the phase change temperature. The latent heat storage material 4 exhibiting the following properties is filled. Further, an electric heater 5 for heating the heat storage material 4 is wound around the container 2 . This heater 5 is connected to a t source 7 via a switch 6.

A branch pipe 8 filled with a heat storage material is provided in the rPJW of the container 2 in communication with the heat storage material 4 inside the container 2 . A part of this branch pipe 8, including the connection part with the container 2, is made of a material 1, such as plastic, which has a lower thermal conductivity than the metal constituting the container 2, and the other part 10 is made of a material with a higher thermal conductivity than the metal constituting the container 2. , for example, is made of the same kind of metal as the container 2. In addition, the high thermal conductivity material part 10
A heat dissipation fin 11 is attached to improve heat dissipation. A portion of the heat storage material 4 in the branch pipe 8 that is in contact with the high thermal conductivity material portion 10 is a solid heat storage material 4a (seed material of the W heat material 4).

In such a configuration, when a current flows through the heater 5 by turning on the switch 6, the metal container 2 is heated, and the heat is stored in the heat storage material 4 accordingly.

At this time, the heat of the heater 5 is transmitted to the branch pipe 8 via the container 2, but since the base of the branch pipe 8 is made of a material with low thermal conductivity, the amount of heat transmitted to the branch pipe 8 is extremely small. A high thermal conductivity material section 1 is located beyond the low thermal conductivity material section 9.
0, and since the radiation fins 11 are provided, the heat held by the heat storage material 4 in the branch pipe 8 is quickly dissipated into the surrounding air.

In this way, while suppressing the amount of heat flowing into the branch pipe 8, it is possible to increase the amount of heat flowing out to the surrounding air.

Therefore, there is a heat storage material 4a in the branch pipe 8 that does not melt even when heated and remains in a stable solid state, so after heat storage is completed, the heat retention by the heater 5 is released, the heat storage material 4 is cooled, and the heat is extracted. At this time, it is possible to reliably prevent the heat storage material 4 from becoming supercooled.

Note that the present invention is based on the above-mentioned actual tJt! The present invention is not limited to one example, and similar effects can be obtained by applying the configuration of the present invention, for example, even when heat storage is performed from inside via a heat exchanger or the like.

However, the present invention can be modified and implemented in various ways without departing from the scope of the invention.

[Effects of the Invention] According to the present invention, a portion of the branch pipe connected to the container of the heat storage tank, including the connecting portion (root portion) with the container, is formed of a material with low thermal conductivity, and a curved portion is formed of a material with high thermal conductivity. By using heat dissipation fins in combination with a material with high heat dissipation properties, it is compact and can be used without energy consumption (e.g., air energy consumption). Cooling can be reliably prevented.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a heat storage device according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional heat storage device. 1... Heat storage tank, 2... Container, 3... Heat insulation layer, 4...
...Latent heat storage material, 4a... Heat storage material (solid state), 5.
... Heater, 8... Branch pipe, 9... Low thermal conductivity material part, 10... High thermal conductivity N ring part, 11... Radiation fin. Appearing agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (2)

[Claims] (1) A heat storage tank consisting of a container filled with a latent heat storage material that exhibits a supercooled state at a temperature lower than the phase change temperature and a heat insulating layer provided around the container; In a heat storage device including a branch pipe filled with a heat storage material in succession with the heat storage material in the container, a portion of the branch pipe including the connection portion with the container has a lower thermal conductivity than the container. 1. A heat storage device, characterized in that the pond portion is made of a material having higher thermal conductivity than the portion. (2) The heat storage device according to claim 1, characterized in that a radiation fin is provided in another portion of the branch pipe.