JPS5879081A - Heat storing material composition - Google Patents

Abstract

PURPOSE:The titled heat storing material, consisting of sodium acetate trihydrate and a carboxylic acid, and capable of carrying out the efficient heat exchange without causing the phase separation of anhydrous sodium acetate even on the repeated heat cycles of heat storing and release for a long term. CONSTITUTION:A composition obtained by incorporating sodium acetate trihydrate with preferably 0.1-20wt%, more preferably 1.0-10wt%, 1-6C carboxylic acid. Formic acid, acetic, propionic, n-butyric, isobutyric, valeric, oxalic or malonic acid, may be cited as the carboxylic acid, and acetic acid is particularly preferred. USE:Suitable for the cooling and heating of solar systems utilizing the solar heat.

Description

[Detailed description of the invention] Performance improvement of sodium acetate 5 water oboro used as
do.

Sodium acetate anhydrous has a melting point of 58°C, a heat of fusion of 60 cal/jF per unit weight, and 87 cal per unit structure.
/lC, and is a compound that is expected to be put to practical use as a heat storage material that utilizes solar heat.

However, when the heat cycle of melting heat storage and solidification heat release is repeated over a long period of time, crystals of sodium acetate anhydride gradually precipitate in the system. The production of the anhydrous salt itself does not interfere with the heat cycle, but when it gradually increases in large quantities and begins to settle and accumulate at the bottom of the system, a so-called phase separation phenomenon occurs, making efficient heat extraction impossible. is necessary.

As a countermeasure against this problem, methods have been proposed such as adding a gelling agent such as sodium acetate pentahydrate or encapsulating sodium acetate trihydrate, but the effects are not necessarily sufficient.

However, the inventors of the present invention have conducted extensive research to solve this problem, and have found that a heat storage material composition consisting of sodium acetate pentahydrate and carboxylic acid undergoes a heat cycle of heating and releasing heat over a long period of time. However, the precipitation of sodium acetate anhydride and phase separation due to precipitation 11 do not occur at all, allowing for efficient heat exchange, and the addition of carboxylic acid slightly lowers the condensation point of sodium acetate trihydrate, so it is relatively The inventors discovered that even if an inexpensive heat collector is used, remarkable effects such as being able to efficiently obtain a predetermined amount of heat can be achieved, and the invention has been completed.

Any uninvented carboxylic acid may be used, but considering the compatibility with water and the effect of preventing phase separation, it is preferable to have a carbon number of 1 to 6.
carboxylic acids are preferably used.

Specifically, citric acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid, valeric acid, succinic acid, malonic acid, succinic acid, fumaric acid, α-tartaric acid, citric acid, dl-malic acid, acrylic acid, glyoxylic acid. , glycolic acid, monochloro vinegar-,
Examples include dichloroacetic acid and glycine, which may be used alone or in combination. Among these, acetic acid is particularly advantageous.

The amount of carboxylic acid is 0.1 to 20% of the total composition.
#i is preferably selected from the range of 1.0 to 10% by weight. If it is less than 0.1% by weight, the effect will be poor, while if it is more than 20% by weight, the amount of heat storage will decrease.

When the heat storage material composition IIIK is used, a small amount of other heat storage materials,
It is also possible to use arbitrary components such as a heat storage aid.

The heat storage material composition thus obtained is suitably used for heating in a solar system that utilizes solar heat, and is capable of performing a stable heat cycle over a long period of time.

Next, the uninvented heat storage material will be explained in more detail by giving an example.

Example 1 Sodium acetate trihydrate qa, 5yK acetic acid9. yyt was added and heated to 80° C. to uniformly dissolve the mixture to obtain a heat storage material composition.

(The freezing point of the composition is 51.oC)
A heat cycle of 0.degree. C. to 45.degree. C. was repeated. Even after repeating the heat cycle 120 times, no phase separation was observed.

On the other hand, when the use of acetic acid was omitted (freezing point was 58°C)
Gradually, precipitation of sodium acetate trihydrate was observed, and 120
After the first cycle, only 65% of the initial heat storage amount was released.

Examples 2 to 54 Experiments similar to those in Example 1 were conducted using various carboxylic acids shown in 21. The results are shown in the table.

Claims (1)

[Claims] 1. A heat storage material composition comprising sodium acetate filtrate and carboxylic acid. 2. The composition according to claim 1, wherein the content of 1 JkM is 0.1 to 20% by weight. & The composition according to claim 91, wherein the carboxylic acid has 1 to 6 carbon atoms.