JPS5956099A - Manufacture of heat accumulating agent - Google Patents

Abstract

PURPOSE:To obtain the heat accumulating agent having a large latent heat by a method wherein sodium sulfate, having a particle size constituent below a specified mesh is 79wt% or more, is utilized as the material of the heat accumulating agent. CONSTITUTION:The sodium sulfate (Na2SO4), with particle size constituent below a particle size of 100 mesh and preferably below 150 mesh is 70wt% or more, is utilized as the material of the heat accumulating agent. The adding amount of the sodium sulfate is determined by dividing an amount, in which the amounts of an overcooling preventing agent and other adding agent are substrated from the total amount of the heat accumulating agent, in accordance with the ratio of the sodium sulfate to water.

Description

[Detailed description of the invention] Is A7 Komei sodium monoformate + hydrate? This article relates to the main method of manufacturing heat storage materials. l(!1') In the present invention, the raw material
; acid sodium (+va2so4) and -C'r! r5
The present invention relates to a method for producing a heat storage material using a particle size of 2.

Sodium sulfate + water salt (Na2S1) 4 @ 10 +
120) Regarding the reheating materials that are mainly used, for example, US Pat.
The well-known n Na25f34”
10H20lf, 32. The CK melting point is 0 caz/g, and the melting M cocoon is 0 caz/g. Heat storage materials are manufactured for the purpose of storing total thermal energy in the form of t1 and m8, and dissipating the heat as &:I solidification heat when cold. It is known that Na2SO4.10H20 exhibits a supercooling phenomenon during the phase change of melting and solidification.

Therefore, in order to produce m-heat material ff as a main interest of Na2804-/□H20, does it undergo a phase change at a constant temperature? Supercooling to cause? It is necessary to prevent this.

The above U.S. patent odor uses borax (N) as a supercooling inhibitor.
A method is described in which a2B4O7" 10H20) is added. Furthermore, Na2SO4.10H2Oi"
j: When melting, Na2SO4 and Na(separated into 20, Na
:ll SO4 precipitates.

When this precipitated Na2SO4 settles into the liquid, it is removed.
During solidification: condensation of Na2SO4@to u2o is suppressed) 1. It is not preferable that the amount of water remaining to the point where there is no more water than some of the Na2-day-04 water is incomplete because the latent heat of melting and solidification will decrease. In order to prevent this Na2804 from settling and separating to the bottom of the liquid, a thickening agent is used. 'l will be done. For example, dl (loss)
Z Show J-f-,! ; O/llu publication describes a method in which fumed silicon dioxide is added as a thickening agent. j-ta Na280
A phase change temperature of 4.10H20 is possible within certain limits by the addition of inorganic salts. For example, JP-A-Sho, 3G-3
'ltgt issue publication has NaOノ.

A method of adding melting point regulators such as KCl, NH4O, etc. is described. In this way, Na2SO4' /□H
Heat storage material Q mainly composed of 20, supercooling inhibitor 1. The heat storage material, which is produced by blending a discriminating agent and a melting point regulator as necessary, is a heat storage material mainly composed of Na2SO4. Although latent heat is utilized, the heat storage material manufactured by the above-mentioned known method is Na2804-10H20.
It has the disadvantage that it gives a latent heat of only 2, which is much lower than the value estimated from the theoretical value of the latent heat of a simple substance (<0 cal/g). For example, the patent publication Sho J,! ;-,30//
In the description example of Za No. 0, Na2SO437,Y%
, NaO, g%, sodium borate, t%, fumed silicon dioxide 3, q da to water l♂, J chi (heavy regret)
The composition of is 3.3 BTU/bond (/Kcal/g). Facilities and Horticulture Magazine/Re, 1'7 Q issue? Example description on page 177: Na2SO4・10H209A%,
The composition of Nα2B407@10H20g% (Tunxichi) is /0PI1. /crtl (Convert to specific gravity as llz) - then cal/'g). The fact that only a low latent heat can be sensed means that the heat storage 111 of the heat storage material is low, so the required amount of heat storage material for the specified heat storage is increased, the heat storage device FI7 becomes larger, and the cost increases. It gets expensive. Current VC regarding the inventors
In view of this, as a result of a thorough investigation of the method of increasing heat and θ of the heat storage material with Na2SO4.10H20 as the main phase, we decided to use a material with a specific particle size as the raw material Na2E104. In order to solve the above problems, the present invention has been completed. In the method for producing lla, the raw material sodium sulfate (lla
2So4), the particle size component of 100 mesh 1 or less is 7
9I￥114-% or more must not be used.
! , 1F Bito Sui is a method for manufacturing a ripening shrine.

Phase change of Na2SO4-10H,,O kl iml!
During Sr, it separates into Na2SO4 and H2C, and when it solidifies, it condenses and returns to Na2SO4./+2otrtc.

24゜7Na2so4+10H20 (1) The reaction during melting is a thermal decomposition reaction, so if heat transfer is sufficient, it will proceed completely, but since it is a hydrated ash that is a reaction during solidification, heat transfer alone is not enough. (The mass transfer of Na2SO4 and H2C is controlled by iL. Na25o4 dissolved in water combines with water molecules around n and precipitates as Na2SO4/□H20. Nazso4, which exists as a crystal, is dissolved in water. It then combines with water molecules, causing diffusion and water utilization reactions in the solid-liquid film.The generated Na2SO4.101 (20) precipitates as crystals, suppressing diffusion in the solid-liquid film, and therefore some is not condensed and becomes Na2 so4
It is likely to remain as it is. To prevent this,
To improve the dispersion of 1Ja2sO4 and ensure sufficient contact with H2C? I need.

As described in Till, a casting agent is used for this purpose, but its effect cannot be said to be sufficient.

The present inventors crushed the raw material Na2sO4 and classified it with a sieve, manufactured heat storage materials using Na2sO4 with different particle sizes, and measured the heat of fusion. As a result, the particle size of Na-2sO4 has a large influence. Fine particles of Na2S less than 100 mesh
It depends on the particle size of O'4. Na25 (14”
The phase change of 10H20 is a repetition of thermal decomposition and water utilization reaction as shown in equation (1). Therefore, Na2SO4 is newly generated during thermal 4) solution, disappears during the heel hydration reaction, and becomes Na2S.
O4m10H20 is produced. Na prepared as i charge
Since 2SO4 disappears during the hydration reaction, the raw material Na2 remains even after repeated thermal decomposition and water utilization reactions.
It was unexpected that there would be an effect of the 804 grain size. This phenomenon is caused by the addition of Na to the heat storage material at the time of manufacture.
The finer the particle size of 2-day 04, the larger the surface area of Na2SO4, which improves the contact with H2C.Also, Na2804 is sufficiently dispersed in the three-dimensional network structure created by the thickening agent, and the surrounding area of Na2SO4 increases. ■112 sufficient for
It is assumed that this is due to the presence of 0 molecules. When the particle size of Na2SO4 becomes large, excess or deficiency of H2O molecules occurs locally around Na2so4 in the first J-dimensional network structure, and the sedimentation rate becomes too large, increasing the possibility of sedimentation separation. In this way, it was found that by making the particle size of Na2SO4 entirely fine, sufficient nitridation of Na2SO4 was achieved in the three-dimensional network structure, and that local excess and deficiency of Na2804 and H2O1 was effective in increasing the heat of fusion. It was.

The Na2804 used in the present invention is a commercial product, but the particle size is 100 mesh or less, preferably ID:
It is necessary that the particle size of lj:0 mesh or less is 7oTfc amount Z or more, and for this purpose, pulverization and classification operations are performed as necessary. Does the heat of fusion tend to decrease when the particle size of 100 mesh or less is less than 70% by weight? It's not very clever.

The amount of Addition 2S04 is based on the total amount of heat storage, and the following are the supercooling inhibitors, thickeners, and melting point regulators. This is the amount allocated to the subtracted Na2So4 and H2O, which can be easily calculated. Of the total amount of normal heat storage materials, 27 to 1
It is about 1-7 weight. Borax (
Na2B40□/lH2O) is effectively used, and its addition amount is 2 to 4% by weight.

As the thickening agent, humid silicon dioxide, abatal guide clay or other substances having a thickening effect are used. When using hygroscopic silicon dioxide
Add t7t%. lj Nap/ as a melting point regulator
, IC+37. Inorganic salts such as NH4O are used, and the amount added is o, q per 19a2041 mol per day.
Desired melting point in the range of ~7.0 mol? is the amount needed to obtain it.

As described above, according to the method of the present invention, by using a specific particle size as the raw material Na2SO4, the dispersibility of Na25O4 is completely improved, and as a result, the contact between Na2SO4 and water is improved.
This makes it possible to increase the total latent heat during the phase change of 11a2SO4.10H20. As a result, the number of counterfeit heat storage materials is reduced, which greatly contributes to downsizing of the heat storage device.

The present invention will be described in detail below with reference to practical examples; however, the present invention is not limited to these practical examples in any way. Father, the child in the example is all disputed unless he has a special case: Article d shows.

Examples / and Comparative Examples / Industrial chemical Naz so 4'f (pulverized and classified with a sieve, as shown below, Na2SO4 in the two types of grains is tto, s%
and H2O! ;/J Section, Borax 3.0%, Aerosil, 2
OO (manufactured by Nippon Aerosil Co., Ltd., fumed silicon dioxide) was mixed with s and 0% to produce a heat storage material. (H2O/
Na25O4 molar ratio 10) The heat of fusion of this product was as follows. Measurement of heat of fusion 1l-j 30g of heat storage material was placed in a polyethylene bag and placed in a 300m dewar bottle.
A method was used in which the heat of fusion was calculated from the temperature change of the hot water by pouring it into 1 of hot water.

Na 2 days 04 grains Vli+1 (Kakuryo%j6(cal/
g) Real time] -/, 50 mesh ~ +, 20
0 mesosh 'Ig, 9 comparison 1 river/-#0
Mesh~-T 100 mesh Q0g Example and Comparative Example Heat storage +j was produced by the same method as in Example except that the particle size of NaZSO4 was changed to V as shown below. The measurement was performed and the following result 4 was obtained.

Claims (1)

[Claims] In a method for producing a heat storage material mainly containing 4A of sodium sulfate + hydrate, the raw material sodium sulfate (Na2S()4
) contains 701 particles with a particle size of 100 mesoyu or less! A manufacturing method for heat storage A, which is characterized by using sardines of I or higher grade.