JPS62199680A - Heat storage material - Google Patents

Abstract

PURPOSE:To obtain the titled material enabling heat storage unit to be simply designed, free from both coagulation point and latent heat drops, with small degree of supercooling, by incorporating polyethylene glycol with specific additive(s) such as anhydrous sodium carbonate. CONSTITUTION:The objective heat storage material can be obtained by incorporating (A) polyethylene glycol with a molecular weight pref. 100-7,000 with (B) so additive(s), pref. 0.01-10wt% of at least one kind of substance selected from anhydrous sodium carbonate, anhydrous potassium carbonate, anhydrous lithium carbonate and zeolite.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat storage material mainly composed of polyethylene glycol having a molecular weight ranging from about 100 to about 7,000.

[Conventional technology]

JP-A-59-174683 relates to a conventional heat storage material based on polyethylene glycol.

JP-A-60-53585, JP-A-59-140283
There is something called a number. Polyethylene glycol has a high hygroscopic property, and when it contains water, its freezing point and temperature decrease, and the degree of supercooling increases, causing problems in actual use. The conventional heat storage material is as follows.

No consideration was given to this.

[Problem that the invention seeks to solve]

As mentioned above, conventional heat storage materials made of polyethylene glycol have hygroscopic properties, so they contain moisture during use.
Freezing point and passion are lowered. In addition, polyethylene glycol that does not contain water is said to be supercooled by about 2"C, but when water is added, the degree of supercooling increases to about 5°C. Compared to the temperature of inorganic room water, the degree of supercooling is generally small. However, depending on the usage, even this level of supercooling may not be allowed.

For example, the freezing point of polyethylene glycol #400 is 5.
℃, but if this is stored in a heat storage capsule and a 4℃ fluid is flowed outside the capsule and solidified over f minutes while exchanging heat, the degree of supercooling is 2℃ (supercooling recovery). Even if the temperature is 3'C), the heat storage material cannot be solidified.

An object of the present invention is to provide a heat storage material that can prevent a decrease in freezing point and latent heat due to moisture absorption, and can also reduce the degree of supercooling.

[Means for solving problems]

For the above purpose, anhydrous N32 COa r anhydrous K 2 CO
3+ anhydrous MyCOa, anhydrous L12COs, v zeolites, etc., is achieved by the addition of one or more substances. That is, the feature of the present invention lies in the use of an anhydrous inorganic substance that dissolves in polyethylene glycol. [Function] The above-mentioned substance adsorbs moisture contained in polyethylene glycol, lowers the freezing point of the heat storage material, Decrease in latent heat? It has the effect of preventing the crystallization of polyethylene glycol itself and suppressing the degree of supercooling to 0.5° C. or less.

〔Example〕

[Example 1] Polyethylene glycol #+0Oy2, 10 of n in a polyethylene container with a lid, anhydrous Na2CO3 of 1
2 was added, and two solidification-melting heat cycle tests were conducted using cold water and hot water. The initial freezing point of this heat storage material is 5℃
, latent heat is 36 Cat/f.

The degree of supercooling was below 0.5℃, but heat cycle 1
No change was observed even after 000 times. [Example 2] Polyethylene glycol + 5ooo was placed in a polyethylene container with a lid for 1002 people, and anhydrous MyCOs 0.
1? , Zeolite 0.1? A solidification-melting heat cycle test was conducted using cold water and hot water. The initial freezing point of this heat storage material is 56°C.

Although the latent heat was 46 Cat/f and the degree of supercooling was 0.5° C. or less, no change was observed even after 1000 heat cycles.

[Example 3] Put 1 ook of polyethylene glycol 16000 into a polyethylene container with a lid, and add anhydrous Kg C030,
1? , anhydrous Laz COa 0.1 f + zeolite 0.12 was added, and a heat cycle test solution of solidification-melting was performed using cold water and hot water. The initial freezing point of this heat storage material is 56°C, the latent heat is 46 Cat/l, and the degree of supercooling is 0.5.
℃ or less, but no change was observed even after 1000 heat cycles.0 Polyethylene glycol #'600. Similar tests were conducted for +1000° +1540, etc., but the amount of additives such as 0 NHzCOa t K2CO3 was 0, which obtained the same effect as in the above example.
．． 01! Even fi:% is effective, and the larger the amount added, the more effective it is, but if it is too large, the heat storage density of the heat storage material will be reduced, so the upper limit is preferably about 10% by weight.

[Comparative Example 1] Polyethylene glycol #400f: 100 was placed in a polyethylene container with a lid, and a heat cycle test of solidification and melting was conducted using cold water and hot water without adding any additives. The initial freezing point of this heat storage material was 5"C9 latent heat was 36 Cat/?, and the appropriate cooling was 2°C (supercooling recovery temperature was 3°C), but after 1000 heat cycles, the freezing point decreased. 30° latent heat decreased to 28 Cat/f/', and the degree of supercooling changed to 5°C (supercooling recovery temperature was -2'C).During the heat cycle, air containing moisture from the outside was released through the lid. Due to intrusion into the container.

[Comparative Example 2] Polyethylene glycol + 6ooov was placed in a nylon bag at 100 f, and a heat cycle test of solidification and melting was conducted using cold water and hot water without adding any additives.0 The initial freezing point of this heat storage material was 56℃, A fever is 46 Cat/
l *The degree of supercooling was 3°C (the supercooling recovery temperature was 53°C), but the freezing point was 52°C after 1000 heat cycles.
°C, a heat changed to 37 Cat/f, and the degree of supercooling changed to 6 °C (supercooling recovery temperature was 46 °C). During the heat cycle, air containing moisture entered the bag through pinholes and defective seals in the nylon bag.

[Comparative Example 3] 100 f of polyethylene glycol #6ooo was placed in a container made of At, and inorganic hydrate NazC was added as an additive.
Os ・10H20 to 1? After the addition, the container was completely sealed by welding. The initial freezing point of this heat storage material is 56℃
, the latent heat was 415 cat/f, the degree of supercooling was 3°C (supercooling recovery temperature was 53°C), but the heat cycle was 100
After 0 cycles, the freezing point is 53'C.

The latent heat changed to 39 Ca4/7 + the degree of supercooling changed to 5°C (supercooling recovery -! degree is 48'C). Hydrates were found to be ineffective.

〔Effect of the invention〕

As described above, according to the present invention, there is no decrease in the freezing point and latent heat of the heat storage material mainly composed of polyethylene glycol, and the degree of supercooling is also suppressed to a low level, thereby facilitating the thermal design of the heat storage device.

[Brief explanation of drawings]

Claims (1)

[Claims] 1. Anhydrous Na added to polyethylene glycol as an additive.
_2CO_3, anhydrous K_2CO_3, anhydrous MgCO_3
, anhydrous Li_2CO_3, and zeolite. 2. The heat storage material according to claim 1, wherein the amount of the additive is 0.01 to 10% by weight.