JPS6092383A - Thermal energy storage material - Google Patents

Abstract

PURPOSE:To provide a thermal energy storage material which is immune from supercooling, shows minimized separation phenomenon and has constant storing and releasing property, prepd. by mixing sodium hydrogenphosphate into a sodium acetate-contg. aqueous soln. CONSTITUTION:Disodium hydrogenphosphate is mixed into an aqueous soln. which contains 50-60.28wt% sodium acetate pref. in an amt. of 0.5-20pts.wt. per 100pts.wt. aqueous soln. The resultant thermal energy storage material can be used in any applications where stored thermal energy is to be utilized, including air conditioning.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a latent heat storage material containing 0HsCO2Na.3H20 as a main component.

Conventional configurations and their problems There are known heat storage materials that utilize the sensible heat of substances and those that utilize latent heat. A heat storage material that uses latent heat has a larger amount of heat storage per unit weight than a heat storage material that uses sensible heat.

In particular, heat storage materials that utilize the latent heat of fusion of inorganic water salts are known to have a large amount of heat storage per unit weight and per unit volume.

Incidentally, CH3GO2Na.3H20ii has been known to be a substance with a particularly large latent heat of fusion among inorganic hydrated salts. However, CHsCO2Na・3H20
1. Once melted, it tends to become supercooled, and the melt may not solidify even if it is cooled to O'C.

When supercooled, the latent heat of fusion is not released, which is a fatal drawback for heat storage materials that utilize latent heat. In order to solve this problem, a method of adding anhydrous CH3CO2Na and other Na salts has been proposed. However, in this method, anhydrous CH3CO2Na is added to GH3CO2Na/3H20, so heat storage and heat radiation are repeated. At the same time, the so-called phase separation phenomenon in which anhydrous CjH3CO2Na rapidly precipitates progresses at an accelerated pace, resulting in a decrease in the amount of heat storage.

Aim of the Invention 3.2' The present invention provides a heat storage material that does not cause supercooling and has stable heat storage and heat radiation characteristics with a small phase separation phenomenon.

Structure of the Invention The feature of the present invention is that CH3CO2Na is contained in a proportion of 50% by weight.
wt% to 60,28wt% (CH3CO2Na・3
(equivalent to the composition of H20).
2HPO4 is added and mixed. Desirably, Na2)T is added to 100 parts by weight of the aqueous sodium acetate solution.
This is the case when PO4 is in the range of 0.5 parts by weight to 20 parts by weight.

Description of Examples Commercially available reagents CHsCOzNa-sHzo and Na2H
Using PO4° and distilled water, 10 og of a sample mixed with O in a predetermined amount as shown in Table 1 was sealed in a stainless steel capsule. The amount of heat stored in each sample was then measured using the drop method. The capsule containing the sample was kept at 65° C. in a water bath for about 3 hours to melt all the CHsCOzNa. After that, about 40
The capsule was placed in a thermos flask (Japanese Patent Application Laid-Open No. 92383(2)) containing water at a temperature of 0.degree. C., and the amount of heat stored in the sample was determined from the rise in water temperature at that time. After that, the capsule was placed in the water bath again and heated and cooled repeatedly between 70°C and 50"C. The temperature of the sample was measured with a thermocouple attached to the surface of the capsule. Through this temperature measurement, each sample's The behavior of heat storage and heat radiation was confirmed. After heating and cooling were repeated 5 times, the amount of heat stored in the sample was measured again using the drop method.

The results are shown in Table 2. Table 2 shows that the amount of heat storage after repeating heating and cooling 50 times is 65 ca#/
Items less than ``g'' are marked with a circle, and 50 to 5
Those with 5caβ/g are shown with a Δ mark, and those with tsocal/g or less are shown with an x mark. By the way, it goes without saying that the ones marked with ○ have a large amount of heat storage and can be put to practical use, and the ones marked with △ have a small amount of heat storage but operate stably, so they can be put into practical use. It is something that can be considered.

5. Analyze the data in Table 1, page 6, Table 2, Table 2. Samples 1 to 7 are Na
The mixing amount of 2HPOa is CH3CO2Na aqueous solution 1oO7
(H5CO2
The concentration of Na aqueous solution was increased from 47.5 wt% to 63 wt%.
CH3C was varied within the range of 0 trials 1 to 1.
Since the concentration of O2Na is low at 47.5 wt %, the heat storage amount is small at 43 cal/g. In sample 2, CH3C0z
Since the concentration of Na is 50 wt, which is higher than that of sample 1, the amount of heat storage is also large, rsocal/g. As the concentration of samples 3, 4.5 and CH3CO5Ja increases, the amount of heat storage increases accordingly. 1st
The amount of heat storage is large at 70 cal/g, but after repeating heating and cooling 60 times, it becomes 57 cal/g.

This is considered to be due to the precipitation of anhydrous Cl5COzNa, a so-called phase separation phenomenon. And CH3C
In sample 7 with an O2Na concentration of 63.0 wt4, the phase separation phenomenon was remarkable, so the first heat storage amount was 63 c.
al/g is large, but after repeating heating and cooling 50 times, it significantly decreases to 49 cal/g.

Samples 8 to 14 are (concentrated T of H5CO2Ha aqueous solution)
! taSho GO-92383 (3) While keeping the degree constant at 58 wt%, the mixed amount of Na2HPO4 was 0 to 100 parts by weight of 0HsQO2Na aqueous solution.
．． The amount was varied within the range of 1 part by weight to 30 parts by weight. For sample 8 in which the mixed amount of Na2HPO4 was 0.1 parts by weight, after repeating temperature measurement, heating and cooling five times, GHs
CO2Nakai 3H20 no longer crystallizes. Therefore, the amount of heat stored in the first cycle is large at 68 cal/g, but the amount of heat stored after repeating heating and cooling 60 times is 13 cal/g.
It became very small. Mixed amount of Na2HPO4 is 0
．． Sample 9 containing 5 parts by weight was heated and cooled 50 times, and the heat was stored and released smoothly. And sample 1o
When the mixed amount of Na 2 HPO 4 increased from Sample 14 to Sample 14, the proportion of the GH 5 CO 2 Na aqueous solution decreased accordingly, and as a matter of course, the amount of heat storage also decreased.

In sample 14 where the mixed amount of Na2HPO4 was 30 parts by weight,
The amount of heat stored after repeating heating and cooling 50 times is 48 cal
/g.

As mentioned above, Na is added to an aqueous solution containing CH3CO2Na in the range of 50 wt% to 60.28 wt%.
By mixing 2HPO4, a heat storage material with stable heat storage and heat radiation characteristics can be obtained. The desired Na2
The amount of HPO4 mixed is within the range of 0.5 parts by weight to 20 parts by weight based on 100 parts by weight of the J5CO2Na aqueous solution.

Effects of the Invention The present invention provides CH3CO2Na at 50 wt% as described above.
In an aqueous solution containing GH in the range of 80.28 wt% from
In order to promote the crystallization of s002Na・3H20, N
Since it is a heat storage material mixed with a2HPO4, supercooling phenomenon does not occur, phase separation phenomenon is small, and it has stable heat storage and heat radiation characteristics. Therefore, the present invention is suitable for use in heat storage devices for air conditioning, etc. It can be applied in all areas.

Claims (2)

[Claims] (1) 50w of sodium acetate (CHsCO2Na)
A heat storage material made by adding and mixing disodium hydrogen phosphate (Na 2HPO4) to an aqueous solution containing in the range of t % to 60.28 wt %. (2) Acetic acid The heat storage material according to claim 1, wherein the amount of disodium hydrogen phosphate is in the range of 0.5 parts by weight to 20 parts by weight based on 100 parts by weight of the IJium aqueous solution.