JPS5941382A - Heat storage material - Google Patents

Abstract

PURPOSE:To obtain a heat storage material with rapid heat release, by adding a sedimentation-proof agent in an aqueous solution of a specific concentration range of calcium chloride. CONSTITUTION:Calcium chloride (including its dihydrate and tetralydrate) is dissolved in water to make an aqueous solution with a concentration of 55.8-75.2wt% followed by adding pref. 1-30wt% based on the amount of the final solution, of a sedimentation-proof agent (pref. asbestos powder, kaolin clay, pulverized silica or alumina, silica gel, diatomaceous earth, glass or mica powder), thus obtaining the objective heat storage material. When heated, this material stores the sensible heat corresponding to each specific heat value of calcium chloride dihydrate and tetrahydrate. When the temperature reaches the solid phase line 1, the tetrahydrate melts into a liquid phase while storing the latent heat, resulting in the uniform dispersion of dihydrate particles owing to the sedimentation-proof agent with the dihydrate and liquid phase coexisting. Further heating leads to the storage of the sensible heat according to each specific heat value of the dihydrate and liquid phase until the liquid phase line 2 is reached. Subsequent cooling leads to the release of the sensible heat until the solid phase line 1 is reached, when the dihydrate particle-nucleated tetrahydrate separates out while releasing the latent heat previously stored, thus resulting in a solid phase to effect the release of the sensible heat.

Description

DETAILED DESCRIPTION OF THE INVENTION More specifically, the present invention relates to a calcium chloride water-based heat storage material that has a high heat dissipation rate.

Carunium chloride hexahydrate (OaOj!!2-61120) has traditionally attracted attention as a water-based heat storage material based on calcium chloride, but calcium chloride hexahydrate has major drawbacks as a heat storage material such as excessive supercooling. had.

Therefore, various additives have been proposed as measures to prevent supercooling, and supercooling has been reduced. However, because calcium chloride filtrate has a slow crystallization rate, it is suitable for heat storage and release over long periods (weeks to seasons), but not suitable for short periods (hours to days). There was a problem.

As a result of intensive research to obtain a heat storage material with a fast crystallization rate suitable for the above-mentioned short period (hours to days), the inventor Ki has found that
By adding an anti-settling agent to a calcium chloride solution in a certain concentration range.

It was discovered that a heat storage material with excellent properties can be obtained.
This completes the present invention. That is.

In the present invention, the amount of calcium chloride in the aqueous solution is 558 to 75.
The gist of the present invention is a heat storage material comprising at least a calcium chloride aqueous solution having a weight ratio of 2 and an anti-settling agent.

The reason why the heat storage material of the present invention has a fast crystallization speed.

It is not certain whether it is suitable for short-term use (hours to days), but it is inferred as follows.

In the heat storage material of the present invention, the amount of calcium chloride in the aqueous solution is 55.
Since the base material is a calcium chloride aqueous solution, the calcium chloride-water system equilibrium state diagram (first
Calunium chloride 2
Two phases coexist: hydrate crystals and calcium chloride solution.

Calcium chloride dihydrate crystals are uniformly dispersed in the calcium chloride aqueous solution phase in order to prevent calcium chloride/rum dihydrate from settling due to the thickening effect of the antisettling agent or the entanglement effect with the crystals.

As a result, it is thought that upon cooling, crystal growth of calcium chloride tetrahydrate occurs rapidly using calcium chloride dihydrate as the nucleus.

Each component used in the present invention will be explained below.

Calcium chloride is an anhydrous salt that can be mixed with water to obtain a calcium chloride aqueous solution.

Dihydrate salt and tetrahydrate salt can be used, and the amount used is 558 to 75258 to 752 in terms of anhydrous salt in calcium chloride aqueous solution.
If the weight part is less than 88 weight φ, there is a problem that supercooling becomes large.

If the amount exceeds 75252 parts by weight, the melting point will become too high to be used as a heat storage material.

Next, as an anti-settling agent, one or more of asbestos powder, kaolin earth, finely powdered silica, finely powdered alumina, Noriyoku gel, diatomaceous earth, glass powder, and mica powder can be used, and the amount used is It is preferably 1 to 30% by weight based on the total amount of the heat storage material. If it is less than 1 part by weight, there will be no effect, causing a problem that calcium chloride dihydrate crystals will settle, and if it is more than 300 parts by weight, a problem will occur such that the amount of heat storage decreases.

In addition to the above ingredients, commonly used crystal nuclei^,
Additives such as good thermal conductors can also be added as appropriate.

Next, the method for manufacturing the heat storage material of the present invention will be briefly described.

First, the necessary amounts of Cal/Rum chloride (including dihydrate and tetrahydrate salts), water, and anti-settling agent are mixed, and the mixture is heated and stirred to form a homogeneous liquid, if necessary.

Additives such as a crystal nucleating agent and a good thermal conductor may be added as appropriate.

Next, the heat storage/dissipation state of the present invention will be explained using FIG. 1.

When the heat storage material of the present invention is heated, it stores sensible heat corresponding to the specific heat of each of calcium chloride tetrahydrate and dihydrate, and the temperature rises to the solidus line 1 of calcium chloride tetrahydrate in FIG. When this temperature is reached, the tetrahydrate accumulates the latent heat of fusion and melts into a liquid phase, and the dihydrate and liquid phase coexist, and the dihydrate particles do not settle due to the action of the anti-settling agent and are uniformly distributed in the liquid. are distributed in

If heating is continued further, sensible heat corresponding to the specific heat of the dihydrate and liquid phase will be accumulated up to liquidus line 2 in Figure 1.5 When cooling is continued, sensible heat will be accumulated up to solidus line 1. When the heat is radiated and the solidus line 1 is reached, there is a slight supercooling, and then tetrahydrate is precipitated with the dihydrate particles as the nucleus while radiating the latent heat of fusion.

They become the same phase, and from then on, the sensible heat of the same phase is dissipated.

Next, the present invention will be explained in detail with reference to examples.

In the examples, "parts" indicate "parts by weight."

Example 1 Calcium chloride 72 parts, k
'° part kaolin soil
Part Z2 The above components were mixed and heated (70° C.) and stirred to obtain a heat storage material.

Example 2 Chloride 72 parts water

Part 28 Wax Season End Shiυ Power 6.
6 parts A heat storage material was obtained using the same ingredients as in Example 1.

Example 6 Cal chloride/rum 72 parts water

28th division Keinwu soil 1
2 parts A heat storage material was obtained using the above components in the same manner as in Example 1.

Example 4 Calcium chloride 72 parts water

28 parts asbestos powder
A heat storage material was obtained in the same manner as in Example 1 using the same ingredients as in Example 1.

Comparative example 1 Calcium chloride 72 parts water

28 parts A heat storage material was obtained using the same ingredients as in Example 1.

Comparative Example 2 Calcium chloride hexahydrate IOO parts Strontium chloride hexahydrate 5 parts Kaolin earth
10 copies of heat storage paper were obtained in the same manner as in Example 1 above.

Examples 1-4. Table 1 shows the test results of the heat storage material obtained in Comparative Example 1.2.

Table 1 (Note 1): There was no heat release for more than 10 minutes, and phase separation occurred.

(Note 2)...There was no heat radiation for 10 minutes or more.

*1...Examples 1 to 4. A test tube with an inner diameter of 10 M was filled with 5 f/ of the heat storage material obtained in Comparative Example 1.2.

Seal with a rubber stopper with a thermocouple attached to the center, 70°C and 25°
10 heating and cooling cycles between water baths maintained at C.
It was repeated 0 times, and the freezing point at the 1st, 10th, and 100th times and the time from the start of cooling to 1 when solidification was completed were measured.

As shown above, the heat storage material of the present invention has a high heat dissipation rate, is suitable for short-term use (hours to days), and can withstand repeated use over time. It is an excellent material and is suitable as a heat storage material for solar collectors, heating, etc. that requires rapid heat dissipation.

[Brief explanation of the drawing]

FIG. 1 is an equilibrium diagram of the calcium chloride-water system. 1... Solidus line of calcium chloride tetrahydrate 2...
...Liquid phase line patent applicant Bentel Co., Ltd.

Claims (1)

[Claims] (1) The amount of calcium chloride in the aqueous solution is 558 to 75.2
A heat storage material characterized by being slightly cloudy due to the weight factor Cal chloride/rum aqueous solution and anti-settling agent. +21 The anti-settling agent is asbestos powder or kaolin soil. Fine powder/Rica, fine powder alumina, silica gel. The heat storage material according to claim 1, which is one or more of diatomaceous earth, glass powder, and mica powder.