JPS5924797B2 - heat storage tank - Google Patents

Description

Detailed Description of the Invention The present invention relates to a heat storage tank using a heat storage material that undergoes a solid-liquid phase change at a predetermined temperature, and particularly to a heat storage tank that prevents overcooling of the heat storage material and stabilizes its operating temperature. It is related to.

Conventionally, hypo (sodium thiosulfate pentahydrate, Na2S2O
Hydrates such as 3.5H20) have a large latent heat of fusion, and if the latent heat during fusion is used for heat storage, the volume of the heat storage material will be smaller for the same amount of heat storage compared to a heat storage material that uses sensible heat such as water. Therefore, practical application has been considered, but once these hydrates are melted, they do not solidify easily even if cooled below their melting point, and often remain in a so-called supercooled state, which has delayed the development of methods to prevent supercooling. This has prevented its practical application.

In order to reduce this supercooling state, use the ice crystal itself as a seed crystal and use appropriate means in the low temperature part of the heat storage tank or outside to preserve it so that it will not melt even when the heat storage material is melting. This was the only practical way to do so.

However, the method of preserving the seed crystals in the heat storage tank using a heat insulating material has the disadvantage that the effective volume inside the heat storage tank becomes small, and the method of installing the seed crystal preservation tube outside the heat storage tank has the disadvantage that the seed crystal preservation tube itself is In addition to being a source of heat dissipation, it also had the disadvantages of complicating the configuration of the device.

In addition, the reality is that no so-called supercooling prevention material has been found to be of any practical use, except when mirabilite is used as a heat storage material.

This invention overcomes all such drawbacks of conventional devices and
The purpose of the present invention is to provide a simple, inexpensive, and practical heat storage tank with a structure that can effectively prevent supercooling of hydrates that easily supercool, such as hypo, and guarantee its effect over a long period of time. .

FIG. 1 is a schematic vertical cross-sectional view showing the configuration of an embodiment of the present invention. In the figure, 1 is a container of a heat storage tank, 2 is a heat storage material housed in the container 1, and 3 is a part of the heat storage material 2. 4 is an insulating liquid such as fluid paraffin sealed in the porous tube 3; 5 is a stirring device for stirring the insulating liquid 4; 6 is a stirring device 5; This is the motor that drives the.

Now, a case will be described in which the heat storage material 2 is a hypo aqueous solution with a Na2S203 concentration of 61% by weight, the insulating liquid 4 is liquid paraffin, and the porous tube 3 is a bacterial r-vortex tube with an inner diameter of 20 mm.

The bacterial vortex tube has numerous micropores of O41 to 1μ on the tube wall.

When the temperature of the heat storage material 2 drops several degrees below the melting point of hypo, 48°C, by rotating the stirring device 5 several times, crystals of hypo will appear on the outer surface of the porous tube 3 after a few minutes, and the temperature will disappear in a short time. The entire porous tube 3 is covered with hypo crystals.

Thereafter, these hypo crystals begin to grow on the fin plate 1 (not shown) of the heat exchanger installed in the container 1, and at the same time the hypo liquid temperature rises to 48°C.
The temperature is maintained at 48°C until the latent heat of fusion is released.

Although there are still many points that are not clear about the mechanism of this supercooling prevention effect, the supercooling prevention effect itself appears reliably and reproducibly. It can be used as a material for a long time.

The porous material tube used is not limited to the bacterial vortex tube, but may also include inorganic materials such as chamotte tubes, bisque tubes, and glass filter tubes with pore diameters of 0.1 to 100μ.
Organic materials such as collodion film and cellophane can also be used if appropriate reinforcing materials are used.

However, if the pore size is larger than 100μ, the heat storage material will penetrate into the porous tube, causing problems.
If the pore diameter is 1 μm or less, the supercooling prevention effect is hardly observed, so it can be said that the pore diameter is practically limited to a range of 0.1 to 100 μm.

In addition to liquid paraffin, the insulating liquid used includes octane,
Paraffins such as decane, dodecane, tetradecane, or pentadecane and mineral oil-based insulating oils such as various transformer oils can be used and have exactly the same effect as liquid paraffin.

As the material for the propeller of the stirring device, in addition to insulating materials such as Teflon, polyethylene, acrylic, vinyl chloride, and polystyrene, metals such as aluminum and stainless steel can also be used.

The driving device is not limited to a motor, but a pie break or the like can also be used.

In addition, this heat storage material is not limited to hypo, but includes sodium acetate trihydrate, disodium hydrogen phosphate dihydrate (Na2' HP 04 ・12H20), calcium chloride hexahydrate (CaC1 ・6H20 ), hydrates such as calcium nitrate tetrahydrate (c a (NO3)2 .4H20) can also be used as heat storage materials.

FIG. 2 is a schematic longitudinal cross-sectional view showing the structure of another embodiment of the present invention, in which 7 is a porous pipe partially immersed in the heat storage material 2 and forming a circulation pipe for the irresistible liquid 4; This pump is installed in the circulation pipe and drives the insulating liquid 4 in circulation.

The heat storage material overcooling prevention function and effect of this embodiment device are almost the same as the embodiment shown in FIG.

Hereinafter, a case will be described in which members of various parts different from those in the embodiment shown in FIG. 1 are used.

A sodium acetate aqueous solution with a NaCH3COO concentration of 57% by weight was used as the heat storage material 2, tetradecane was used as the insulating liquid 4, and a chamotte tube (inner diameter 30 mm) was used as the porous tube 7. At this point, when tetradecane is circulated through the porous tube 7 at a rate of about 500 cc/min by the pump 8, the supercooling is immediately broken, the temperature of the heat storage material 2 recovers to 58°C, and the release of latent heat of solidification is completed. The temperature was maintained at 58°C.

Even in a slow heat cycle, overcooling could always be prevented and stable operation could be achieved over a long period of time.

In this device, if an obstacle wall made of plastic is provided or an obstacle is inserted in order to obstruct the flow of the insulating liquid 4 within the porous tube 7, the reliability of the supercooling prevention effect will be further improved.

FIG. 3 shows a schematic vertical cross-sectional view of still another example of the compact supercooling prevention device used in the present invention.

In the figure, 9 is a vibrating element coated with polyethylene, etc.;
0 is a vibration fulcrum, and 11 is an electromagnet that vibrates and drives the vibrating piece 9. These constitute a vibrator 12.

That is, by passing an alternating current or an intermittent current through the electromagnet 11, the vibrating piece 9 vibrates in the direction of the arrow shown in the figure, thereby stirring the insulating liquid 4 within the porous tube 3.

This supercooling prevention device has the same effect as the one used in the embodiment shown in FIG. It can be operated at a uniform temperature inside.

As detailed above, according to the present invention, the insulating liquid sealed in the porous tube immersed in the heat storage material penetrates the tube wall and promotes crystallization of the heat storage material, thereby supercooling the heat storage material. A small heat storage tank with stable operating temperature can be easily realized.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical cross-sectional view showing the configuration of an embodiment of the present invention;
FIG. 2 is a schematic vertical cross-sectional view showing the configuration of another embodiment of the present invention, and FIG. 3 is a schematic vertical cross-sectional view showing the configuration of still another example of the compact supercooling prevention device used in the present invention. In the figure, 1 is a container, 2 is a heat storage material, 3 and 7 are porous tubes, 4 is an insulating liquid, 5 is a stirring device, 8 is a pump, and 12 is a stirring vibrator. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A container containing a heat storage material that undergoes a solid-liquid phase change at a predetermined temperature, made of a porous material having a large number of pores with a pore diameter of 0.1 to 100 μm, at least a part of which is contained in the heat storage material. A porous tube arranged by being immersed, an insulating liquid sealed in the porous tube and penetrating the wall of the porous tube to promote crystallization of the heat storage material, and insulation in the porous tube. A heat storage tank equipped with a flow device that allows liquid to flow. 2. The heat storage tank according to claim 1, wherein a stirring device for stirring the insulating liquid is used as the flow device. 3. Claim 1, characterized in that the porous pipe is configured to form a circulation pipe, and the flow device uses a pump that drives the insulating liquid to circulate through the circulation pipe. The heat storage tank described. 4. The heat storage tank according to any one of claims 1 to 3, wherein the heat storage material is sodium thiosulfate pentahydrate. 5. The heat storage tank according to any one of claims 1 to 3, wherein the heat storage material is sodium acetate trihydrate. 6. The heat storage tank according to any one of claims 1 to 3, wherein the heat storage material is disodium hydrogen phosphate-technical water salt. 7. The heat storage tank according to any one of claims 1 to 3, wherein the heat storage material is calcium chloride hexahydrate. 8. The heat storage tank according to any one of claims 1 to 3, wherein the heat storage material is calcium nitrate tetrahydrate. 9 Claim 1 in which a bacteria permeation tube is used as a porous tube
The heat storage tank according to any one of Items 8 to 9. 10. The heat storage tank according to claim 1, wherein a chamotte tube is used as the porous tube. 11. The heat storage tank according to any one of claims 1 to 8, in which an unglazed tube is used as the porous tube. 12. The heat storage tank according to claim 1, wherein a glass filter tube is used as the porous tube. 13 Claims 1 to 8 in which an organic thin film such as a collodion film or a cellophane film is used for the porous tube
The heat storage tank described in any of the paragraphs. 14. The heat storage tank according to any one of claims 1 to 13, wherein the insulating liquid is one selected from the group consisting of liquid paraffin and paraffins of octane, tecasdodecastetradecane, and pentadecane. . 15. The heat storage tank according to any one of claims 1 to 13, wherein mineral oil-based insulating oil is used as the insulating liquid.