JPH07316535A - Method for melting snow or preventing freezing by using thermal storage material composition - Google Patents

Abstract

PURPOSE:To carry out snow melting and freezing prevention of an open-air structure such as a road without using a heat source device of an artificial means and without polluting an environment, by using a semipermeably usable thermal storage material composition comprising an inorganic hydrated salt, a supercooling inhibitor and a phase separation inhibitor. CONSTITUTION:A thermal storage material composition comprising (A) at least one inorganic hydrated salt (preferably sodium sulfate decahydrate), (B) 0.1-10wt.% of a supercooling inhibitor (preferably at least one of borax, a silicate and cryolite) and (C) 0.1-10wt.% of a phase separation inhibitor (preferably at least one of carboxymethyl cellulose, attapulgite clay and a water-insoluble water-absorbing resin) and has preferably 0-10 deg.C) freezing point is packed into a container, which is arranged on an open-air structure such a road, a bridge. The composition accumulates heat during rise in temperature and causes a change in phase during drop in temperature and latent heat is released to melt snow and to prevent freezing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing snow melting or freezing of an outdoor structure using a heat storage material composition, which is used as a road, a bridge, a parking lot, a plaza, a sidewalk,
There are curved mirrors, traffic signs, road guide boards, roofs, roof tiles and fences.

[0002]

2. Description of the Related Art As a method for preventing snow melting and freezing, roads,
In outdoor structures such as bridges, parking lots, plazas, and sidewalks, snow melting agents are sprayed, water is sprayed onto the road surface, and hot water pipes or heaters are laid under the road surface. It is feared that the spray of snow-melting agent will corrode the car body and piers of automobiles and cause environmental pollution. Sprinkling water on the road surface is effective, but it uses a large amount of water, so running costs are high and there is a problem in effective use of water resources. The method of laying a hot water pipe or heater under the road surface is also effective, but the hot water pipe method has a drawback that the running cost becomes high because hot water is made by the heat source device of artificial means and circulates this. is there. This is also the case when a heater is used, and in any case, there is a strong demand for a reduction in running cost. In addition, equipment that provides important information for cars and motorcycles to pass, such as curve mirrors, traffic signs and road signs installed to prevent traffic accidents, adheres to powder snow in winter. However, as the temperature drops, the snow that adheres to it often freezes and does not perform its intended function. For safety, it is strongly required that these devices always function, but at present, there is no effective means.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to prevent snow melting or freezing by using a heat storage material composition which can be used semipermanently without using a heat source device of artificial means and without polluting the environment. It is in the provision of methods.

[0004]

Means for Solving the Problems The present invention provides "1. A heat storage material composition comprising at least one kind of an inorganic hydrated salt, a supercooling inhibitor and a phase separation inhibitor, for a road, a bridge,
A method of preventing snow melting or freezing by arranging it in outdoor structures such as, and storing heat when the temperature rises and radiating latent heat by phase change when it falls. 2. The freezing point of the heat storage material composition is higher than 0 ° C. and 10
The method for preventing snow melting or freezing according to item 1, wherein the method is less than ° C. 3. The method for preventing snow melting or freezing according to Item 1 or 2, wherein the inorganic hydrated salt of the heat storage material composition is sodium sulfate decahydrate. 4. The heat storage material composition comprises sodium sulfate decahydrate and ammonium chloride, ammonium bromide, sodium chloride, sodium bromide, potassium chloride, potassium bromide, ammonium sulfate, sodium sulfate, potassium sulfate, ammonium nitrate, sodium nitrate and potassium nitrate. The method for preventing snow melting or freezing according to any one of items 1 to 3, which contains at least one or two or more inorganic salts selected from the group. 5. 0.1-10 wt% of at least one supercooling inhibitor selected from the group consisting of borax, silicate and cryolite, and selected from the group consisting of carboxymethyl cellulose, attapulghai clay and water-insoluble water-absorbent resin The method for preventing snow melting or freezing as described in any one of Items 1 to 4, which comprises 0.1 to 10% by weight of at least one phase separation inhibitor. 6. 1 to 5 wherein the supercooling inhibitor is borax
The method for preventing snow melting or freezing according to any one of items. 7. The phase separation inhibitor is a water-insoluble water-absorbent resin,
The method for preventing snow melting or freezing according to any one of items 1 to 6. 8. Fill the container with heat storage material and place it in the outdoor structure,
The method for preventing snow melting or freezing according to any one of items 1 to 7. Regarding

[0005]

A feature of the method for preventing snow melting or freezing according to the present invention is that heat is transferred in and out as latent heat when the heat storage material composition solidifies and melts due to changes in air temperature. No running cost is required because it is not necessary. Specifically, when the heat storage material composition undergoes a phase change from liquid to solid (solidification), heat is released to the outside as latent heat of solidification, and when the heat storage material composition undergoes a phase change from solid to liquid (melting), latent heat of fusion It utilizes the phenomenon of absorbing heat from the outside. Therefore, before the road or bridge freezes due to a decrease in temperature, the heat storage material composition laid under the road surface or in the bridge begins to solidify, releasing latent heat of solidification to reduce the temperature of the road surface or bridge surface to zero. It is kept above ℃ to prevent freezing. In addition, the heat storage material composition that has once solidified and released the latent heat of solidification is heated by the rise of the daytime temperature and melted to store heat. In this way, a method for preventing snow melting or freezing that does not require an artificial heat source device becomes possible by storing heat and radiating heat by using the temperature difference due to the change in the daily temperature.

[0006] Specifically, it is considered that the road surface and the bridge surface are frozen at a surface temperature of 0 ° C to -1 ° C due to the influence of wind and the like. Therefore, it is desirable that the freezing point of the heat storage material composition is higher than 0 ° C. Water can be considered as the heat storage material composition, but since the solidification temperature is 0 ° C., it is considered that the solidification temperature is too low to prevent freezing and is not suitable. Further, if the freezing point is too high, there is a problem that heat cannot be taken out near the temperature at which solidification actually begins. Therefore, the solidification temperature is 10 ° C or lower, preferably 7 ° C or lower. The melting temperature of the heat storage material composition is preferably the same as the solidification temperature, but the melting temperature of the heat storage material composition using the inorganic hydrate salt tends to be slightly higher than the solidification temperature.
Assuming that the surface temperature of the road surface during the daytime rises to about 15 ° C, the average melting temperature of the heat storage material composition is 13 ° C or less, preferably 10 ° C or less.

As a heat storage material composition having a freezing point in the range of 0 ° C. to 10 ° C., paraffinic tetradecane (C ₁₄ H
₃₀ , freezing point 5.9 ° C), pentadecane (C ₁₄ H ₃₂ , freezing point 9.9 ° C), non-paraffin polyethylene glycol # 400 (freezing point 4-8 ° C) and 1-decanol (5 ° C).
℃) etc. However, many of these organic substances correspond to dangerous substances under the Fire Defense Law, and there is a problem of environmental pollution when they leak from the heat storage container, so it is a heat storage material composition that should be used in a large amount as much as possible. Therefore, there is a demand for an inorganic salt heat storage material that is safe and does not pollute the environment.

Examples of the inorganic hydrated salt used in the heat storage material composition of the present invention include sodium sulfate decahydrate, calcium chloride hexahydrate, and disodium hydrogen phosphate dodecahydrate. The use of sodium sulfate decahydrate is preferred. Sodium sulfate decahydrate has a melting point of 3
The temperature is 2.5 ° C., and the latent heat amount is 60 cal / g. Also,
In order to adjust the freezing point of sodium sulfate decahydrate to 10 ° C. or lower, ammonium chloride, ammonium bromide, sodium chloride, sodium bromide, potassium chloride, potassium bromide, ammonium sulfate, sodium sulfate, potassium sulfate, ammonium nitrate, nitric acid At least one or more inorganic salts selected from the group consisting of sodium and potassium nitrate are blended, and among them, ammonium chloride, ammonium bromide, sodium chloride, sodium bromide, ammonium sulfate and sodium sulfate are preferable.

The heat storage material composition used in the present invention consists essentially of the above-mentioned inorganic hydrated salt and one other salt, but may further contain a supercooling inhibitor and a phase separation inhibitor. . Examples of the supercooling inhibitor that can be used in the heat storage material composition used in the present invention include borax, silicate, and cryolite, and borax is preferable. The compounding amount of the supercooling inhibitor is 0.1 to 10% by weight, preferably 0.5 to 5% by weight, based on the weight of the composition.

Examples of the phase separation inhibitor that can be used in the heat storage material composition of the present invention include carboxymethyl cellulose, attapulghai clay, water-insoluble water-absorbent resin, sodium alginate, gelatin, agar, wood pulp, silica gel, diatom. Soil etc. can be mentioned, among them, carboxymethyl cellulose, attapulghai clay, water-insoluble water-absorbent resin, for example, cross-linked polyacrylate, vinyl acetate-partially saponified acrylic acid copolymer,
A starch-acrylic acid graft copolymer is preferred. The compounding amount of the phase separation inhibitor is 0.1 to 10% by weight, preferably 0.5 to 5% by weight, based on the weight of the composition. By using these phase separation inhibitors, a heat storage material composition having stable long-term recycling performance can be obtained.

Next, the operation of the present invention will be described in terms of practical implementation of the invention. Snow melting and freezing prevention on roads, bridges, parking lots, plazas, and sidewalks When general roads, motorways, highways, bridges, and other road surfaces freeze and the road functions impair traffic functions such as accidents and congestion There are many. Therefore, by burying a container filled with the heat storage material composition under the road surface and paving concrete or asphalt on the container, it is possible to prevent freezing without using an artificial heat source device. The shape of the container filled with the heat storage material is not particularly limited, but a relatively thin shape having good thermal conductivity such as a plate shape, a pipe shape, a spherical shape, or a coil shape is preferable. The material of the container is also not particularly limited, but those having corrosion resistance to inorganic salts are preferable, and various plastics, stainless steel, zinc steel pipe and the like can be mentioned, and among them, various plastics are more preferable. In addition to roads, it can also be used for parking lots, plazas and sidewalks. It can be used for snow melting as well as for freezing prevention, and if a small amount of snow falls, it is possible to melt snow only with the heat storage amount obtained from the heat storage material composition. Even if the total amount of snowfall is large and it is not possible to melt the snow entirely with the amount of heat obtained from the heat storage material composition, the surface layer such as the road on which the heat storage material is placed has been melted by snow, so snow removal by people or snow removal Work efficiency can be improved.

Snow melting and freezing prevention of curve mirrors, traffic signs, road guide boards, etc. Cars, motorcycles, etc., such as curve mirrors, traffic signs, and traffic guide boards that are installed to prevent traffic accidents, pass by. It is often the case that a device that provides important information for snow does not perform its original function because powder snow adheres to it in the winter, and the snow that adheres freezes as the temperature drops. Therefore, by filling the inside of these devices with the heat storage material composition, it is possible to prevent the adhesion of powdered snow and the like and the prevention of freezing of the adhered snow due to a decrease in temperature, and these devices can always function. .

Snow melting and freezing prevention of roofs, roof tiles, fences, etc. In heavy snow areas, it is necessary to lower the snow accumulated on the roof quite frequently in order to prevent houses from collapsing. Therefore, since the heat storage material composition filled in the roof and roof tiles releases heat, the amount of snow that falls is less likely to accumulate on the roof, and even if there is a large amount of snow, the snow in the surface layer of the roof melts. , It naturally slides off the roof, so snow removal can be omitted or simplified.

[0014]

EXAMPLES The present invention will be specifically described by showing a method for preparing a heat storage material composition, heat evaluation thereof, and a method for preventing snow melting and freezing.
Table 1 shows examples of the heat storage material composition that can be used in the snow melting or freezing prevention method of the present invention. It is preferable to use the heat storage material composition shown in Table 1, but it is not limited to this.

Example 1 (Preparation of composition of heat storage material) Sodium sulfate decahydrate,
Ammonium chloride, sodium chloride, sodium sulfate,
Sodium bromide and ammonium sulfate were mixed in the proportions shown in Table 1, and then borax was added as a supercooling inhibitor in an amount of 1.5 parts by weight to 100 parts by weight of a sodium sulfate-based hydrate, and a phase separation inhibitor in water. An insoluble water absorbent resin (Sunwet, IM-1000, manufactured by Sanyo Kasei Co., Ltd.) was added in an amount of 1.5 parts by weight to 100 parts by weight of sodium sulfate-based hydrate, and the mixture was stirred with a mixer to prepare a composition. At this time, it is very important to stir the composition until it is sufficiently homogeneous, and if the stirring is not sufficient, the amount of heat as designed cannot be obtained, and therefore care must be taken. (Thermal evaluation) The obtained composition was -10 ° C to 4 by DSC.
The amount of latent heat was measured in the temperature range of 0 ° C. Further, about 180 g of the composition was filled in a resin capsule having a diameter of about 70 mm, and a thermocouple for recording a change in temperature was fixed to the center of the capsule. Put this capsule in a temperature-controllable water tank,
The temperature of the water tank was kept at 1 ° C., and the solidification temperature of the heat storage material composition was measured. In the solidification process, the temperature rises as the metastable supercooled state is broken and the heat storage material solidifies to release latent heat. At this time, the highest temperature reached is the solidification temperature. Next, after the heat storage material composition was completely solidified, the temperature of the water tank was changed to 11 ° C (13 for Example Nos. 4, 5 and 6).
C.) and the melting temperature of the heat storage material composition was measured. In the melting process, since the present heat storage material composition is a mixture and has a certain melting temperature, the average temperature from the start of melting to the end of melting is defined as the average melting temperature. Table 1 shows the measurement results of the heat storage amount, the solidification temperature and the melting temperature. The composition of Example 1 will be described as an example of the solidification and melting behavior of the heat storage material composition that can be used in the present invention. The temperature change of the central portion of the composition of Example 1 during solidification and melting is shown in FIG. In FIG. 1, 0 to 9 hours is the solidification process of the heat storage material composition. Water temperature from 11 ℃ to 1 ℃ in 1 hour
And then held at 1 ° C. for 8 hours. The composition of Example 1 does not change its state from the start until 2 hours, and the temperature is lowered. After 2 hours, the metastable supercooled state was broken at 3.0 ° C. and solidification started. At this time, in order to release the latent heat of solidification, the temperature of the composition of Example 1 rose to 3.1 ° C., and solidification proceeded. From the start of the coagulation process up to 9 hours,
It can be seen that the latent heat of solidification is stably released. afterwards,
Crystallization was completed and the material temperature became equal to the temperature of the water bath. In actual use, the latent heat of solidification is released from 2 hours to 9 hours after the start of the solidification process, and the temperature of the road surface and bridge surface is kept at 0 ° C or higher to prevent freezing. Therefore, the freezing temperature is 0
It is possible to use a heat storage material composition having a temperature of ℃ or higher. The compositions of Examples 1 to 6 all have a solidification temperature of 0 ° C. or higher, which indicates that they are heat storage material compositions suitable for the present invention. In FIG. 1, 9 to 17 hours are the melting process of the heat storage material.
From 9 hours to 10 hours, 1 ℃ to 11 ℃ in 1 hour
The water temperature was raised to 11 ° C. for 7 hours.
The material temperature increased without changing the state until 10 hours, the melting started from 10 hours, and the melting continued until about 14 hours. Then, the melting was completed and the temperature of the material became equal to the temperature of the water tank. At this time, the composition of Example 1 was 6.5 ° C. to 8.1 ° C.
It can be seen that the heat is melted in the range of ℃, and the amount of heat released is taken in as latent heat of fusion to store heat. In actual usage,
If the road surface temperature or bridge surface temperature during the day becomes higher than the melting temperature, heat can be stored. Assuming that the surface temperature of the road surface during the day rises to about 15 ° C, the average melting temperature of the heat storage material composition is 13 ° C or lower, preferably 10 ° C or lower. Example 1
The compositions of Nos. 6 to 6 all have an average melting temperature of 13 ° C. or lower, and even the composition of Example 6 having the highest average melting temperature has a melting temperature of 1 or less.
It is 0.9 degreeC. The other compositions of Examples 1 to 5 all had an average melting temperature of 10 ° C. or lower, which shows that the composition is a heat storage material composition suitable for the present invention.

[0016]

[Table 1]

(Freezing Prevention Method) The composition of Example 1 is filled in a resin plate container having a volume of 50 cm ³ , and about 5 g of water is left on the container. The container containing the heat storage material was put in a freezer whose temperature was adjusted to -3 ° C, and it was examined whether or not the water in the upper portion was solidified. As a comparative example, 5 g of water was similarly put on the same container filled with sand, and it was examined whether or not the water on the upper part solidified. After 2 hours, the water on the container of Comparative Example was solidified, but the water on the container filled with the composition of Example 1 was not solidified. The water on the container filled with the composition of Example 1 completely solidified after 4 hours. From this result, it was confirmed that freezing of water on the container can be prevented by the latent heat of solidification of the heat storage material. Next, the above-mentioned heat storage material composition was filled in a plastic container, buried under the road surface during snowfall, and asphalt pavement was carried out to a thickness of 3 cm, and a practical test was conducted under natural snowfall. About 10 cm of snow was observed on the road surface without heat storage material embedded, but there is no snow on the road surface with heat storage material embedded, indicating that the snow melting effect is excellent.

Examples 2 to 6 A heat storage composition was obtained in the same manner as in Example 1 except that the composition ratios were as shown in Table 1, and the heat storage amount and the like were measured using this, and the results are shown in a table. Shown in 1.

[0019]

INDUSTRIAL APPLICABILITY The present invention has an excellent effect of preventing snow melting and freezing of outdoor structures such as roads without using an artificial heat source device.

[Brief description of drawings]

FIG. 1 is a graph showing a temperature change during solidification and melting of a heat storage material composition used in the present invention.

Claims (8)

[Claims] 1. A heat storage material composition comprising at least one inorganic hydrate salt, a supercooling inhibitor and a phase separation inhibitor,
A method for preventing snow melting or freezing by arranging on outdoor structures such as bridges, storing heat when the temperature rises and radiating latent heat by phase change when it falls. 2. The method for preventing snow melting or freezing according to claim 1, wherein the heat storage material composition has a freezing point of higher than 0 ° C. and lower than 10 ° C. 3. The method for preventing snow melting or freezing according to claim 1, wherein the inorganic hydrated salt of the heat storage material composition is sodium sulfate decahydrate. 4. The heat storage material composition comprises sodium sulfate 10
Hydrated salt and at least one or two selected from the group consisting of ammonium chloride, ammonium bromide, sodium chloride, sodium bromide, potassium chloride, potassium bromide, ammonium sulfate, sodium sulfate, potassium sulfate, ammonium nitrate, sodium nitrate and potassium nitrate. The method for preventing snow melting or freezing according to any one of claims 1 to 3, containing the above-mentioned inorganic salt. 5. At least one supercooling inhibitor selected from the group consisting of borax, silicate and cryolite 0.1 to 1
0% by weight and 0.1-10% by weight of at least one phase separation inhibitor selected from the group consisting of carboxymethyl cellulose, attapulghai clay and water-insoluble water-absorbent resin. The method for preventing snow melting or freezing according to item 1. 6. The snow melting or freezing prevention method according to claim 1, wherein the supercooling preventive agent is borax. 7. The method for preventing snow melting or freezing according to claim 1, wherein the phase separation inhibitor is a water-insoluble water absorbent resin. 8. The snow melting or freezing prevention method according to claim 1, wherein the container is filled with the heat storage material and the heat storage material is placed in an outdoor structure.