JPS6342196B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heat storage device used in latent heat type, regenerative heating and cooling devices, etc., and more specifically, the present invention relates to a heat storage device that prevents overcooling of a heat storage material and quickly changes the phase from a liquid phase to a solid phase. The present invention relates to a heat storage device that can be used to store heat.

Note that in this document, the heat storage material refers to latent heat type heat storage materials that have cold heat storage and hot heat storage functions.

In a heat storage device that stores heat by utilizing the latent heat of fusion of a heat storage material, it is recommended to use hypo(Na ₂ S ₂ O ₃・5H ₂ O; heat of fusion
48cal/gr, melting point 48℃) and calcium nitrate (Ca
(NO ₃ ) ₂・4H ₂ O; heat of fusion 34 cal/gr, melting point 42°C),
Or ammonium alum (NH ₄ Al
(SO ₄ ) ₂・12H ₂ O; heat of fusion 60cal/gr, melting point 94℃)
Inorganic compounds with water of crystallization, such as , are used as heat storage materials, but these substances generally have a large degree of supercooling, which poses a serious obstacle to regenerative heating and cooling systems. That is, when heat is extracted from the heat storage tank during heating, if the heat storage material is overcooled, the heat stored as latent heat cannot be extracted. On the other hand, during cooling, if the heat storage material is supercooled to below the temperature of the refrigerant entering the heat storage tank, a phase change from liquid phase to solid phase will not occur, making it impossible to store cold heat in the form of latent heat. Therefore, how to prevent supercooling is a major practical problem. For this reason, various methods for preventing supercooling have been attempted, but the most reliable method is to bring the crystals of the material itself into contact with the melt of the heat storage material in a heat storage state. To achieve this, it is necessary to preserve this seed crystal in the heat storage device, and for this reason, for example, as described in Utility Model Application Publication No. 52-126651, through holes are formed in a part of the heat insulating wall. It has been proposed to maintain the heat storage material in a crystalline state at the outer end of the through-hole (the part that touches the tank wall) and allow it to crystallize from this part during heat dissipation. This was not always sufficient, as it caused extra heat loss at the parts that touched the surface.

The present invention has a novel device for preserving seed crystals,
The purpose of this is to provide a heat storage tank that effectively prevents supercooling of the heat storage material, and its feature is that the seed crystals can be preserved without excessive heat loss. This is possible, and a large amount of secondary seed crystals are generated and supplied for the phase change from liquid phase to solid phase, making the phase change possible quickly. Next, embodiments of the present invention will be described using the drawings.

In Fig. 1, 1 is a heat storage tank, 2 is a heat exchanger (only the brine tube is shown, and the fins are not shown), 3 is a heat storage material made of ammonium alum, and 4 is external insulation of the heat storage tank for heat retention. Layer 5 is a heat insulating material made of glass wool mat provided on the top of the heat exchanger 2 so as to be thermally conductively connected to the heat insulating layer 4 and at least partially immersed in the heat storage material 3. This heat insulating material 5 has porosity or liquid permeability, is in contact with ammonium alum 3, contains microcrystals thereof, and supplies seed crystals.

In the heat storage device of the present invention configured as described above, it is currently in a heat storage state, and the temperature T of the heat storage material 3 is higher than the melting point T _M , and the temperature of the heat insulating layer 4 is at the melting point.
Suppose that it is below T _M. Since the upper surface of the heat insulating material 5 is thermally conductively connected to the heat insulating layer 4, the temperature T _s of the upper surface becomes below the melting point of the heat storage material 3, and the temperature inside the heat insulating material 5 made of a porous or liquid-permeable material is lower than the melting point of the heat storage material 3. The heat storage material 3 that has permeated into the heat storage material 3 is preserved as a seed crystal in the upper part of the heat insulation material 5. Next, when heat is dissipated and T becomes equal to or less than _TM , crystal growth occurs from the preserved seed crystal, and solidification progresses in the lower part of the figure in the heat insulating material 5. The insulation material 5 has complex continuous pores of various sizes ranging from 1 μm in size to several hundreds of μm in size, and these are impregnated with heat storage materials such as ammonium and alum. A large number of secondary seed crystals are generated from the stored seed crystals, and very small, fine grained secondary seed crystals are supplied to the heat exchanger 2 from the entire lower surface of the glass wool mat that constitutes the insulation material. . In this way, the degree of supercooling is small and crystal formation proceeds smoothly throughout the entire interior of the heat storage tank 1. This is the gist of the present invention, and in the above embodiment, glass wool mat was used as the heat insulating material 5, but silica or silica alumina wool, glass fiber, asbestos, sintered glass, porous porcelain wood brick, or low temperature In some cases, this effect can be obtained by using a porous material containing many continuous pores or a liquid-permeable heat insulating material such as polyurethane. In this book, these materials are collectively referred to as "insulation materials."

In order to preserve the seed crystals, it is necessary to create a portion whose temperature is lower than the melting point of the heat storage material 3, and for this reason, the normal method involves excessive heat loss, which impairs the performance of the heat storage device. Another feature of the present invention is that the seed crystal is preserved without excessive heat loss.The first embodiment, the basic configuration of which is shown in FIG. 1 above, will be described in more detail below. .

As shown in Fig. 2, the outside air temperature is Ta, the temperature of the heat storage material is T, and the thickness of the heat insulating layer 4 outside the heat storage tank is d.
Further, assuming that the thermal conductivity is K, the heat loss Q ₀ per unit area through this heat insulating layer 4 is expressed as Q ₀ =T-Ta/dK (1).

In the present invention, the heat storage material 3 is impregnated into the heat insulating material 5 provided inside the heat storage tank 1 as described above.
Now, let the thickness of the insulation material 5 be d ₁ , and its thermal conductivity is
K ₁ and the temperature of the upper surface portion 51 of the heat insulating material 5 are assumed to be T _s .
Further, if the thickness of the heat insulating layer 4 in the part of the heat insulating material 5 is d ₂ , then the heat loss Q per unit area through these layers is as follows: Q = T - T _s /d ₁ K ₁ = T _s - Ta / d ₂ K ......(2)

Q≦Q ₀ ………(3) That is, T−T _s /d ₁ K ₁ ≦T−Ta/dK ………(4) By lowering T _s below the melting point while satisfying the following condition, excess heat can be removed. Seed crystals can be preserved without loss. In this example using ammonium alum, it is sufficient that T = 97℃ Ta = 30℃ Ts = 91℃ (5), and the insulation layer 4 has the following values: d = 0.08 (m) K = 0.04 (Kcal/ mh℃)......(6). From equation (4), K ₁ /d ₁ ≦T-Ta/T- _Ts K/d=67/6×0.04/0.
It is necessary to satisfy 08=5.58. From this relationship, it can be seen that the thickness d ₁ of the heat insulating material 5 can be reduced as its thermal conductivity K ₁ is smaller. Since the insulation material 5 is impregnated with ammonium/alum, K ₁ is expected to take a value close to that of ammonium/alum.
The experimental result was K ₁ =0.22 (Kcal/mh°C). It was also found that heat transfer by convection does not occur because the heat insulating material 5 is impregnated. As a result,
In this example, d ₁ is 0.04m and d ₂ is 0.073m.
I was able to do this. In this manner, the heat storage tank of the first embodiment was designed, and as a result of testing, a temperature distribution approximately shown in equation (5) was obtained. The heat dissipation characteristics in this example are shown in curve A in FIG. In this figure, the temperature directly below the heat insulating material 5 is plotted on the vertical axis, and the time after the start of heat radiation is plotted on the horizontal axis. As can be seen from curve A, in the first example, supercooling was broken at about 83°C and the temperature rose to 92°C.

A sectional view of the main part of the second embodiment is shown in FIG. In this embodiment, a heat storage tank having almost the same configuration as the first embodiment includes a stirring propeller 6 and a mechanism for driving the stirring propeller, including a propeller-directly connected disk-type multipolar magnet 7, a motor-directly connected disk-type multipolar magnet 8,
A bearing mechanism 9 and a motor 10 are added.
With this stirring mechanism, the propeller 6 can be rotated with an appropriate torque from outside the heat storage tank, which has a closed structure to prevent moisture evaporation of ammonium/alum, and the heat storage material 3 can be stirred. As a result, the rate of supply of secondary crystals from the heat insulating material 5 can be increased, and since the seed crystals are multiplied in the liquid being stirred, the degree of supercooling can be further reduced. This effect is visible in the cooling curve of FIG. That is, the cooling curve in this example is shown by curve B, and it can be seen that supercooling is broken at 88° C., and heat is dissipated with a faster response than curve A. By introducing the rotational power of the propeller 6 from the outside of the heat storage tank using a magnetic coupling, firstly, the sealing problem in the closed tank structure can be solved, and secondly, the propeller can be stopped due to solidification of the heat storage material. It was possible to achieve two effects, which correspond to an increase in the resistance to rotation of the propeller.

A sectional view of the main part of the third embodiment is shown in FIG. In this example, the heat storage tank 1 has almost the same configuration as the first embodiment.
In addition, a device 11 for swinging the heat insulating material 5 is added. This has the effect of increasing the supply rate of the secondary seed crystal from the heat insulating material 5 and reducing the degree of supercooling. This result appears in the cooling curve C of FIG. That is, it can be seen that in this example, supercooling is broken at 86° C., and heat is dissipated with a slower response than curve B but faster than curve A. A rocking device has the advantage of being considerably simpler to construct than a stirring device.

A sectional view of the main part of the fourth embodiment is shown in FIG. In this example, a diaphragm 12 is provided between a heat exchanger 2 and a heat insulating material 5 of a heat storage tank having almost the same configuration as the first embodiment, and this is coupled to an electromagnetic oscillation device 11 by a shaft 14, and the shaft is a bellows frame. By 13,
It is hermetically sealed in the heat storage tank 1 so that it can be moved up and down. The diaphragm used was a copper disk with a thickness of 0.5 mm or a copper disk in which a large number of holes were formed with an openness of about 50%. During heat dissipation operation, the diaphragm is moved by a vibrating device.
When moving up and down at 60Hz with a vibration width of 0.3mm, the insulation material 5
The ammonium alum melt in the vicinity of is violently moved up and down, etc., so that new melt always comes into contact with the crystals that have reached the bottom surface of the insulating material 5. As a result, secondary nucleation is promoted, and the diaphragm 12 Secondary seed crystals are actively supplied to the lower heat exchanger 2 side through the provided holes. As a result, an effect comparable to that of the cooling curve C in FIG. 4 was obtained.

FIG. 7 shows an example in which vibrations are introduced into the heat storage tank 1 by magnetic coupling. That is, vibration is introduced by an electromagnet 16 and an iron piece 15 bonded to a spring plate 17, and the diaphragm 12, which is supported from the spring plate 17 by the shaft 14 at a position 4 mm below the porous heat insulating material 5, is vibrated. By adopting such a structure, even if the vibration power is applied after the heat storage material 3 has been solidified, no mechanical strain is applied. Furthermore, the reliability of the sealing structure could be improved.

FIG. 8 shows an example of another diaphragm. That is,
The openings in the diaphragm 12 are not holes, but holes 18 that are cut and extruded into a fin shape. It has been found that by adopting such a structure, the stirring effect of the heat storage material is further improved, and the generation of secondary seed crystals from the heat insulating material 5 becomes more active.

In the above explanation, an example was explained in which the heat insulating material is provided on the entire upper surface of the heat storage tank, but it goes without saying that the heat insulating material may be provided on one or more arbitrary parts such as the side surface or the bottom surface. do not have. Naturally, the heat storage material is not limited to ammonium and alum.

As detailed above, according to the present invention, it is possible to provide a highly reliable heat storage device using latent heat of fusion, which can reliably prevent overcooling without deteriorating performance such as increased excess heat loss. .

[Brief explanation of the drawing]

1, 3, 5, and 6 are all sectional views of essential parts showing embodiments of the heat storage device of the present invention, FIG. 2 is a diagram for explaining the principle of the present invention, and FIG.
The figure shows the cooling characteristics of the device of the present invention, FIG. 7 is a partial view showing one embodiment of the swinging means, and FIG.
FIG. 2 is a perspective view showing an example of a diaphragm. In the figure 1... heat storage tank, 2... heat exchanger, 3... heat storage material,
4... Heat storage tank outer heat insulation layer, 5... Heat insulating material, 6... Stirring propeller, 11... Vibration device, 12... Vibration plate, 13
... bellow flam, 14...shaft. In addition, in the figure,
The same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A heat storage tank whose periphery is covered with an outer heat insulating layer and which houses a heat storage material inside the heat storage tank, and at least A heat storage device comprising a porous heat insulating material containing many continuous pores or a liquid-permeable heat insulating material, a part of which is immersed in the heat storage material. 2 Insulating materials include glass wool, silica or silica-aluminum wool, asbestos, sintered glass,
The heat storage device according to claim 1, characterized in that the heat storage device is made of at least one of firebrick, porous magnetism, and polyurethane. 3. A heat storage tank whose periphery is covered with an outer heat insulating layer and contains a heat storage material therein, which is thermally conductively coupled to the outer heat insulating layer via the heat storage tank and at least partially contains the heat storage material. 1. A heat storage device comprising: a porous heat insulating material containing many continuous pores or a liquid-permeable heat insulating material provided so as to be immersed in the heat storage material; and a stirring means for stirring the heat storage material. 4. The heat storage device according to claim 3, characterized in that the stirring means comprises a propeller rotatably provided inside the heat storage tank and a drive unit that rotates the propeller via a magnetic coupling device. Device. 5. The heat storage device according to claim 3, wherein the stirring means comprises a diaphragm provided inside the heat storage tank and a drive unit that vibrates the diaphragm. 6. The heat storage device according to claim 5, wherein the diaphragm has a plurality of openings.