JPH0238116B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a heat storage element used in a heat storage tank for storing late-night electricity, solar energy, etc., and in a heat storage body that requires a constant temperature such as a hot curler. It is something.

Conventional structure and problems Conventionally, inorganic salts,
Paraffin and the like are used, but one of the problems in either case is that heat exchange is not carried out quickly. In other words, in the molten state, the temperature in the heat storage material is almost uniform due to convection, but once heat starts to be radiated, the temperature of the heat storage material on the heat transfer surface rapidly decreases due to poor heat transfer in the solid state. This is because the rate at which heat is removed from the heat transfer surface is faster than the rate at which heat is transferred from the heat storage material in the portion away from the heat transfer surface. Therefore, the heat storage material in the immediate vicinity of the heat transfer surface releases its latent heat and solidifies. Once solidified, the thermal conductivity is poor, so the heat storage material at a distance from the heat transfer surface remains in a liquid phase, making it difficult to effectively utilize the latent heat in this area.

For example, in FIG. 1a, a heat storage element 1 is placed in a container 2 made of metal or plastic, and a heat storage material 3 is placed in a container 2 made of metal or plastic.
It is enclosed. When heat is released from the heat transfer surface, the heat storage material 4 releases latent heat and solidifies as shown in Figure 1b.
adheres to the heat transfer surface. Since this solidified heat storage material has poor thermal conductivity, it is difficult to transfer the thermal energy of the heat storage material 3 in a molten state to the heat transfer surface. That is, it is difficult to extract and effectively use the heat of the heat storage element 1 in a relatively short period of time and to obtain heat at a constant temperature for a long period of time.

OBJECTS OF THE INVENTION The present invention solves the above problems and provides a heat storage element with improved heat exchange efficiency.

Structure of the Invention The present invention includes a latent heat storage material in a container, a heat transfer medium that is non-reactive with the latent heat storage material and changes from liquid to gas when absorbing heat and from gas to liquid when heat is released, and the latent heat storage material and The heat transfer medium and non-reactive powder are both encapsulated.

DESCRIPTION OF THE EMBODIMENTS In FIG. 2a, a heat storage element 1 includes a container 2 made of metal or plastic, and a latent heat storage material 3 such as calcium chloride hexahydrate, sodium thiosulfate pentahydrate, or sodium acetate trihydrate, and the latent heat storage material 3. material 3
It is composed of a heat transfer medium 5 such as a material that absorbs more heat, evaporates, releases latent heat on a heat transfer surface, and condenses, such as fluorocarbons or alcohol, and a powder 6 made of metal, carbon, ceramic, or the like.

When the heat storage material 3 is in a molten state (heat storage state), the inside of the container 2 is mainly filled with steam that is in equilibrium with the vapor pressure of the heat storage material 3 (heat storage material filling part) and the working fluid, which is approximately equal to the melting temperature of the heat storage material. It consists of 7 (gas phase part). When heat radiation starts, the vapor of the heat transfer medium in the gas phase releases its heat through the heat transfer surface and condenses and liquefies 8. When condensed and liquefied, the vapor pressure of the gas phase decreases. This causes the heat transfer medium 5 contained in the heat storage material to evaporate, which becomes bubbles 9 and rises in the heat storage material to compensate for the pressure drop. Further, the condensed heat transfer medium drips back into the heat storage material. In this case, if the density of the heat transfer medium is higher than the density of the heat storage material 3 in the molten state, the heat condensate 8 will fall to the lower part of the heat storage material 3, so the effect described later will be more pronounced and the heat transfer will be improved. That is, when the condensed liquid descends in the heat storage material 3, it temporarily absorbs heat from the heat storage material 3 and vaporizes again, and the vapor becomes bubbles 9 and rises. The other part settles to the bottom of the container and absorbs heat from the surroundings and vaporizes again.
In this process of repeating evaporation and condensation of the working fluid, the latent heat storage material is vigorously stirred.

If the density of the heat transfer medium is smaller than the density of the heat storage material, the distance it descends through the heat storage material 3 will be smaller, but
In this embodiment, the powder 6 adheres to the surface of the condensate, increasing its substantial density, and as in the case described above, the condensate falls below the heat storage material filling. This prevents the condensate from evaporating from the surface of the heat storage material, which prevents the temperature of the surface of the heat storage material from decreasing at the gas-liquid interface. This will prevent evaporation into the phase.

On the other hand, in the heat storage material filling section, the heat storage material releases its latent heat through the side surface of the container and solidifies. In this case, since the entire heat storage material is vigorously stirred by the working fluid, the solid matter of the heat storage material that has released latent heat becomes difficult to adhere to the heat transfer surface. Furthermore, even if the solid material adheres, the thickness of the solid material does not grow much, and since the powder 6 is mixed in the heat storage material 3 solid material (these powders generally have better heat transfer than the heat storage material), conventional No significant reduction in heat transfer was observed. Furthermore, since the specific gravity of the solid heat storage material is greater than when it is in a solution state, it settles downward. Therefore, even at the stage where a considerable amount of latent heat is released, the same heat radiation as in the initial stage is performed in the gas phase.

Specific examples will be shown below.

Into a container made of vinyl chloride with an internal volume of approximately 50 c.c., 45 g of sodium acetate trihydrate as a heat storage material, 5 g of Freon R-113 as a heat transfer medium, and 3 g of fine carbon powder as a powder were inserted and sealed to form a heat storage element. did. A large number of these heat storage elements were inserted into a heat storage tank to store heat. When heat was extracted from this heat storage tank, 80% of the total heat dissipated was obtained from hot water of 50°C or higher, which is close to the melting point of sodium acetate trihydrate, 58°C. When the hot water is taken out under the same conditions without inserting the powder, the hot water above 50℃ is 30%, and even above 40℃
It can be seen that the heat dissipation efficiency is significantly improved compared to 70%.

Effect of the invention According to the present invention, there are the following effects.

Since a part of the heat exchange is performed in the gas phase, heat exchange can be performed easily and quickly without creating a solid phase portion with poor heat transfer around the heat transfer surface.

As the vapor of the working fluid passes through the heat storage material in the form of bubbles, the heat storage material is agitated by the bubbles.
In heat exchange in the liquid phase, (a) solid heat storage material is difficult to adhere to the heat transfer surface, and the heat transfer surface and the solution are always in substantial contact;

(b) Temperature distribution becomes almost uniform, and solidification does not start from a certain point.

(c) The solidified heat storage material has a higher specific gravity than in its molten state, so it settles, but in this case, the heat storage material is agitated by air bubbles, so it becomes fine crystals and accumulates at the bottom of the heat storage tank. That is, the heat storage material that has released latent heat gradually sinks to the bottom. Therefore, the latent heat of the entire heat storage material can be effectively utilized.

Therefore, according to the present invention, heat from the heat storage material can be extracted quickly and efficiently.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional heat storage element, and FIG. 2 is a sectional view of a heat storage element according to an embodiment of the present invention. 1... Heat storage element, 2... Container, 3... Heat storage material,
5... Heat transfer medium, 6... Powder.

Claims (1)

[Claims] 1 A latent heat storage material in a container, a heat transfer medium that is non-reactive with the latent heat storage material and changes from liquid to gas when absorbing heat and from gas to liquid when releasing heat, and the latent heat storage material and the heat transfer medium. A heat storage element encapsulated with non-reactive powder.