JPS6119687A - Thermal energy storage material - Google Patents

Abstract

PURPOSE:To provide a thermal energy storage material which is stable, allows stored heat to be dissipated for use under arbitrary temp. conditions at any time and can be repeatedly used many times, consisting of Na2SO4.10H2O, NaCl and a hydrophilic polysaccharide. CONSTITUTION:1-25pts.wt. NaCl and 0.1-10pts.wt. hydrophilic polysaccharide such as xanthane gum having an MW of 2,000,000-50,000,000 and the formula (wherein M<+> is Na, K, 1/2Ca) are mixed with 100pts.wt. Na2SO4.10H2O to obtain a thermal energy storage material. The material is put in a container having a given shape and heated to bring it into hydrogel having stored thermal energy. A seed crystal is added to the hydrogel, or a thin film formed on its surface is molten and stimulation is given to thereby solidify the hydrogel around the seed crystal, thus generating heat.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a new thermal energy storage device, and more specifically, it can be stored by applying heat naturally or artificially, and can be stored at any time and under any temperature conditions (however, The present invention provides a thermal energy storage product that can freely release stored heat in a temperature range below the melting temperature (32°C) of sodium sulfate decahydrate constituting the thermal energy storage product.

[Prior art]

In recent years, as energy resources have become tighter, it has become possible to use sunlight, an inexhaustible energy source, to store thermal energy during the day and release it at night, or to use cheap nighttime electricity to store mature energy and use it during the day. Heat cycle systems that release stored energy are beginning to be considered. Thermal energy storage materials used for such purposes include the sensible heat type, which is represented by water and crushed stone, and the latent heat type, which uses phase change latent heat such as melting caused by inorganic salt hydrates and organic crystalline substances. exists. By the way, in the former case, the capacity and weight of the thermal energy storage device are quite large (and the temperature of the thermal energy storage device itself decreases due to the release of heat, and furthermore, the temperature of the environment in which it is placed may change automatically) On the other hand, the latter has the advantage that the device can be made more compact due to the large phase change latent heat, and the temperature drop of the thermal energy storage itself due to heat dissipation is small.However, this latent heat Like the former sensible heat type, molds also have the problem of spontaneously emitting heat due to changes in the environmental temperature in which they are placed.These characteristics are ideal for agricultural applications, for example. It is useful for applications that maintain a constant temperature.However, it is inconvenient for applications that require the user to release heat for the first time at any time and under any temperature conditions.In other words, it is inconvenient for applications that require the user to release heat for the first time at any time and under any temperature conditions.In other words, it is inconvenient for applications that require the user to release heat for the first time at any time and under any temperature conditions.In other words, it is inconvenient for applications that require the user to release heat for the first time at any time and under any temperature conditions. , they cannot be used for applications that release heat at a desired time.This is a cause of limiting the usability of many latent heat type thermal energy storage devices.

[Problem that the invention seeks to solve]

In view of the above-mentioned current situation, the present inventors used a latent heat type thermal energy storage device to: ■ At any time and under any temperature conditions determined by the user,
A new type of thermal energy storage device that has the properties of being able to freely release stored thermal energy, and being able to exist in a very stable state with thermal energy stored until the energy release period specified above. After repeated research to see if it could be obtained, we arrived at the present invention.

[Structure and outline of the present invention]

That is, the present invention relates to a thermal energy storage product characterized by comprising sodium sulfate decahydrate, sodium chloride, and a hydrophilic polysaccharide.

The hydrophilic polysaccharide, which is one of the components of the thermal energy storage product of the present invention, is a homopolysaccharide, Peter Poly$1! It may be of any kind such as group i or derivatives thereof.

Examples of such hydrophilic polysaccharides include glucans such as cellulose, amylose, laminaran, amylopectin, glycogen, microbial dextran, galactans such as agar agarose, λ-carrageenan, and snail galactan, and fructans such as dalya and Inulin, levan, tritisine, etc. from the Jerusalem artichoke rhizome, xylan from higher plants, mannan from elephant palm, seaweed, or yeast, chitin, an N-acetylglucosamine polymer, pectic acid, a polygalacturonic acid, and homozygotes such as arabinan from peanuts, apples, and sugar beet. Polysaccharides or their derivatives, i.e. alkylation, acetylation, sulfate esterification,
Examples of the cellulose which have been subjected to acetic acid esterification include carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, dihydroxyethyl cellulose, and hydroxypropyl cellulose.

Alternatively, D-glucose and D-mannose are β
Konjac mannan, which is a glucomannoglycan with 1 → 4 bonds, glucomannan from wood, galactoglucomannoglycan from coniferous wood, where D-galactose is branched with α1 → 6 bonds on the glucomannan main chain, and guar gum. (guaran), larch arabinogalactoglycan,
Heteropolysaccharides such as gum arabic, tragacanthic acid from gum tragacanth, alginic acid, glycosaminoglycans, locust bean gum, etc., or derivatives thereof, and extracellular heteropolysaccharide, which is a type of heteropolysaccharide, that is, bacterial Xan
Pseud, a xanthan gum whose constituent units are D-glucose, D-mannose, and D-glucuronic acid obtained from a medium of thomonas compestris.

D- obtained from the medium of the mucoid strain of -monas
Mannuronic acid, a heteropolysaccharide having L-curcuronic acid as a constituent unit, A, D-glucuronic acid obtained from an indicum medium, D-glycero-D-mannoheptose, D
-Mixtures of acidic heteropolysaccharides whose constituent units are glucose and D-mannose and neutral heteropolysaccharides whose constituent units are D-glucose, D-mannose, L-arabinose, and L-rhamnose, or derivatives thereof. be able to. Among these, xanthan gum, hydroxyalkylcellulose such as hydroxyethylcellulose, hydroxyalkylcellulose such as hydroxyethylcellulose, Hydroxyalkylated guar gums such as propylated guar gum are preferred, and xanthan gum is particularly preferred since it has the best balance of these.

Generally, xanthan gum is sold by Kelco as “Keltrol”.
KELTROL) J and [KELZAN
Hydroxypropylated guar gum is commercially available under the trade name Jaguar HP-11J and is readily available.

Xanthan gum (xanthan) is considered to have a repeating unit as shown in the following general formula (1), and most of its molecular weights are about 2 million to 50 million.

M''=Na+K, or '/2CaThe xanthan gum represented by the above general formula (I) is produced by converting thorium sulfate decahydrate, which is another constituent and has a latent heat due to phase change, into a hydrogel in the presence of sodium chloride. As a result, it does not release latent heat and solidify even below the melting point of sodium sulfate decahydrate (and remains stable even under various mechanical stimuli, such as vibrations and shocks). It is possible to eliminate the possibility of releasing latent heat.

In the present invention, the above-mentioned hydrophilic polysaccharides can be used, but these may be used alone or in combination of two or more. Particularly suitable is a system in which xanthan gum, which has remarkable effects, is the main component and other polysaccharides are mixed therein. At this time, there is no particular restriction on the mixing ratio, and it is possible to mix at any desired ratio, but preferably the xanthan gum is at least half the amount. A feature of these mixtures is that they require less amount of xanthan gum to produce the same thickening effect and stabilize the thermal energy store than when using xanthan gum alone, thus resulting in a more efficient thermal energy store. .

In order to obtain the thermal energy storage product of the present invention, a hydrophilic polysaccharide is blended into a system of sodium sulfate decahydrate and sodium chloride.The proportion of these blends is not particularly limited, but from the viewpoint of thermal efficiency. From 1 to 25 parts by weight of sodium chloride, preferably 3 to 20 parts by weight, particularly preferably 5 to 1 part by weight, per 100 parts by weight of sodium sulfate decahydrate.
5 parts by weight and 0.1 to 10 parts by weight of the hydrophilic polysaccharide, preferably 0.1 to 5 parts by weight, particularly preferably 3 to 5 parts by weight. In the case of mixtures of xanthan gum and other polysaccharides, the amount is 0.1 to 5 parts by weight, preferably 1 to 2 parts by weight. If the amount of sodium chloride is less than 1 part by weight, a clear thickening and stabilizing effect will not be exhibited, making it impossible to obtain the desired thermal energy storage product. The same applies if the amount of hydrophilic polysaccharide is less than 0.1 part by weight.

Hayabusa energy W''--〇beat, (7) 4 Milk Other embodiments of the thermal energy storage having the above-mentioned structure include other inorganic salts or their hydrates in addition to sodium sulfate. In addition, it is also possible to add various compounds that are commonly added to latent heat type thermal energy storage materials. However, the addition of supercooling inhibitors (nucleating agents) is contrary to the effects of the present invention and should be avoided.

To express the thermal behavior of the thermal energy storage material of the present invention, the following methods can be exemplified.

First, to store thermal energy, a container of any shape filled with the thermal energy storage material of the present invention is exposed to sunlight and solar heat is stored, or a heater generates heat using low-cost electricity at night. A method to store the heat, a method to store the heat of exhaust gas or heated wastewater by heat exchange method, a method to generate electricity using surplus power of rotating machinery and generate heat from a heater and store it, an internal combustion engine such as a car engine. Examples include a method of storing surplus heat.

In order to extract the thermal energy stored in the thermal energy storage material as described above, for example, the thin film formed on the surface (this is thought to be the crystallized solidification of sodium sulfate decahydrate) can be removed using a rod or the like. There are two methods: pushing seed crystals into the molten hydrogel-like interior, and inserting seed crystals from the outside. Among these, it is advantageous to apply stimulation using a rod-shaped body having a crystallized solidified thermal energy storage material having the same structure as the present invention at its tip.

〔Effect of the invention〕

By adopting the above configuration, the present invention has the following advantages: (1) Once sodium sulfate decahydrate melts and stores thermal energy, it becomes a hydrogel-like stable state, which is lower than the melting temperature of sodium sulfate decahydrate. It does not solidify and remains stable even when

(2) In a stable hydrogel-like state, it does not respond to mechanical stimuli such as vibrations or shocks, so there is no need to be nervous about transporting or storing it.

(3) A stable state can continue semi-permanently.

(4) Any time, any temperature condition (sulfuric acid) IJ
The stored heat can be extracted at any time (below the melting temperature of um decahydrate).

(5) It can be used repeatedly any number of times.

It shows excellent effects such as:

[Applications of the present invention]

The thermal energy storage device of the present invention can be applied to various fields by utilizing the above-mentioned effects, such as instant warmers for leisure use such as fishing and diving, instant warmers for use in the military, room heaters for home use, and automobiles. It can be used as a winter preheater for engines and as a decoy for heat-sensitive missiles. It can also be used to store solar heat and transport heat to remote locations.

〔Example〕

The content of the present invention will be explained below with reference to preferred embodiments.
The present invention is not limited to these examples as long as the purpose thereof is not impaired.

Example 1 Sodium sulfate decahydrate (Na2SO4' 1011
20) and sodium chloride (NaCl) in the weight ratios shown in Table 1 were put into the hooker. Next, 3 parts by weight of xanthan gum (Kelzan ■; manufactured by Kelco) was added to 100 parts by weight of the sodium sulfate decahydrate-sodium chloride system, and the beaker was placed in a hot water bath at 50°C for 30 minutes. Stir for a minute to evenly mix the three components.

The mixture thus obtained was filled into a cylindrical polyethylene container, sealed, and left in an atmosphere at 10° C. for 1 hour. After that, the mixtures were left at room temperature (25° C.) for 74 hours, but all the mixtures in the polyethylene containers remained stable in the form of hydrogels. Next, when crystals of sodium sulfate decahydrate were introduced into the container, the mixture, which had been stable in the form of a hydrogel, solidified (crystallized) centering on the introduced crystals and generated heat. Mixture 1 at this time
Table 1 shows the results of measuring the calorific value per gram.

Table 1 Comparative Example The same operation as in Example was carried out except that 3 parts by weight of xanthan gum was added to 100 parts by weight of sodium sulfate decahydrate. As a result, the mixture of the two could not be mixed well to form a hydrogel, and if left to stand, phase separation occurred and solidification did not occur properly, so no heat was generated.

Claims (1)

[Claims] A thermal energy storage product comprising sodium sulfate decahydrate, sodium chloride, and a hydrophilic polysaccharide.