JPS6111987B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a latent heat storage material that utilizes the latent heat of fusion of CH ₃ CO ₂ Na.3H ₂ O. Conventional Structures and Problems There are two known heat storage materials: one that utilizes the sensible heat of a substance, and the other that utilizes the latent heat. Compared to heat storage materials that use sensible heat, heat storage materials that use latent heat have a larger amount of heat storage per unit volume and per unit mass, and only a small amount is required to store the required amount of heat, so it is not possible to store heat. Enables downsizing of equipment. In addition, a heat storage material using latent heat can store heat at a constant temperature at a transition point and can also radiate heat. In particular, heat storage materials that utilize the latent heat of fusion of inorganic hydrates are known to have a large amount of heat storage per unit volume. By the way, it has been conventionally known that CH ₃ CO ₂ Na.3H ₂ O is a substance with a particularly large latent heat of fusion among inorganic hydrates. However, CH ₃ CO ₂ Na・
The melting point of 3H ₂ O is not the harmonic melting point but the peritectic point, so as CH ₃ CO ₂ Na
A so-called phase separation phenomenon progresses, in which the liquid is deposited at the bottom of the container. Therefore, the latent heat of fusion of CH ₃ CO ₂ Na.3H ₂ O naturally decreases due to repeated heat storage and heat release. The reduction in latent heat associated with this phase separation phenomenon has been a major problem when applying CH ₃ CO ₂ Na.3H ₂ O as a heat storage material. OBJECTS OF THE INVENTION The object of the present invention is to provide a latent heat storage material that does not cause phase separation even after repeated melting and solidification and has extremely stable heat dissipation properties. Structure of the Invention The feature of the present invention is that CH ₃ , CO ₂ Na is contained in an amount of 53 to 69% by weight.
In a system consisting of CH ₃ CO ₂ Na and H ₂ O containing within the range,
It is made by adding and mixing polyvinyl alcohol (PVA), formadehyde, and paraffin as thickeners. Preferably, the mixed amount of PVA is 0.5 to 20 parts by weight, the mixed amount of formaldehyde is 0.1 to 5 parts by weight, and the mixed amount of paraffin is 0.1 to 100 parts by weight of the system consisting of CH _{3 CO 2} Na and H 2 O. -5 parts by weight. Description of Examples Commercially available reagents such as CH ₃ CO ₂ Na.3H ₂ O, formaldehyde, PVA, paraffin and H ₂ O were blended in predetermined amounts so as to have the composition shown in Table 1.
Regarding PVA, those with a polymerization degree of approximately 500 and approximately 1500
This study was carried out on three types of objects, approximately 2,000 objects.
For paraffin, commercially available liquid paraffin, paraffin with a melting point of 42°C to 44°C, melting point of 54°C to 56°C
The experiment was conducted on three types of paraffin.

【table】

[Table] Heat the mixture containing the specified amount to about 70℃,
Melt _CH3CO , _Na.3H2O and paraffin;
The mixture was vigorously stirred using a stirrer for about 60 minutes. As a result, a white viscous liquid was obtained. Approximately 100 g of the obtained sample was sealed in a capsule together with 0.5 _g of Na ₄ P ₂ O ₇ .10H ₂ O, which is a supercooling prevention material for CH ₃ CO ₂ Na.3H 2 O. Then, the latent heat of each sample was measured by the drop method. The capsule containing the sample was heated and held at 70°C for about 3 hours to melt the sample, and then the temperature was lowered to about 60°C and held for about 4 more hours. The sample was then placed in a thermos bottle containing water at approximately 30°C, and the latent heat of the sample was determined from the rise in water temperature at that time. Thereafter, the capsule containing the sample was placed in a water bath and heated and cooled between 70°C and 35°C 1000 times. At that time, after 100 times and 1000
The latent heat after spinning was measured by the drop method described above.
The results are shown in Table 2. Table 2 shows the latent heat of 45ca after repeated heating and cooling 1000 times.
If it is more than l/g, please mark it with ○, if it is more than 40cal/g or more, 45cal/
Those with less than 40 cal/g are marked with △, and those with less than 40 cal/g are marked with x. By the way, as a matter of course, those marked with ○ have a large amount of heat storage and can be put to practical use, and those marked with △ have a not so large amount of heat storage, but the heat storage material operates stably, so it is sufficient for practical use. is considered possible.

【table】

[Table] Analyze the data in Table 2. Sample 1 to sample 10
CH ₃ CO ₂ Na content from 52% to 70% by weight
A system consisting of CH ₃ CO ₂ Na and N ₂ O that has been changed to
100 parts by weight, 2 parts by weight of PVA, 0.5 parts by weight of formaldehyde, and 1.0 parts by weight of paraffin were mixed. In sample 1 with a CH ₃ CO ₂ Na content of 52% by weight, the amount of heat released during the first solidification is large at 55 cal/g, but after repeating melting and solidification 1000 times, the latent heat is small at 37 cal/g. Become.
For sample 2, which is a system consisting of CH ₃ CO ₂ Na and H ₂ O and has a CH ₃ CO ₂ Na content of 54 parts by weight, melting and solidification was performed at 1000 parts by weight.
The latent heat after repetition is 50 cal/g, which is considerably larger than that of sample 1. and CH ₃ CO ₂ Na
Samples 2 to 6, in which the system consisting of and H ₂ O contains CH ₃ CO ₂ Na in a range of 54 to 68% by weight, have latent heats of 50 cal/g or more even after repeating melting and solidification 1000 times. However, the system consisting of CH ₃ CO ₂ Na and H ₂ O
For sample 10 with a CH ₂ CO ₂ Na content of 70% by weight,
The latent heat after 1000 cycles is 39 cal/g, which is considerably smaller than Sample 3, which has a large latent heat. In addition, in heat storage materials containing such thickeners, the latent heat is maximized when the composition of the system consisting of CH ₃ CO ₂ Na and H ₂ O is
The stoichiometric composition of CH ₃ CO ₂ Na・3H ₂ O, i.e.
From the 60.28% by weight of CH ₃ CO ₂ Na, it can be seen that the composition is on the excess H ₂ O side, that is, around 56 to 58% by weight of CH ₃ CO ₂ Na. For samples 11 to 17, the system consisting of CH ₃ CO ₂ Na and H ₂ O containing 56% by weight of CH ₃ CO ₂ Na was kept constant at 100 parts by weight, PVA was 2 parts by weight, and formaldehyde was kept at 0.5 parts by weight. The amount of paraffin mixed is 0% by weight.
The content was varied within a range of 10% by weight. In sample 11, which does not contain paraffin, the latent heat at the first run is as large as 57 cal/g, but the latent heat after the 100th run is as high as 57 cal/g.
50 cal/g, the latent heat after 1000 times decreases significantly to 38 cal/g. Sample 12 mixed with 0.1 part by weight of paraffin
Then, the latent heat after 1000 cycles is 49 cal/g, and sample 11
considerably larger compared to and samples containing paraffin in a range of 0.5 parts by weight to 5 parts by weight.
For samples 13 to 16, the latent heat after 1000 cycles is as large as 50 cal/g or more. However, in sample 17 in which 10 parts by weight of paraffin was mixed, the latent heat after 1000 cycles decreased to 44 cal/g. For samples 18 to 22, the system consisting of CH ₃ CO ₂ Na and H ₂ O containing 56% by weight of CH ₃ CO ₂ Na was kept constant at 100 parts by weight, PVA at 2 parts by weight, and paraffin at 1 part by weight. The amount of formaldehyde mixed was varied from 0 parts by weight to 10 parts by weight. In sample 18, which did not contain formaldehyde, the first latent heat was as large as 58 cal/g, but 100
It decreases to 48 cal/g after 1,000 repetitions and 38 cal/g after 1000 repetitions. For sample 19 mixed with 0.1 part by weight of formaldehyde, the latent heat after 1000 cycles was 48 cal/g,
Compared to sample 18, the degree of decrease is considerably smaller. Sample 20 and sample 21 containing formaldehyde in the range of 0.2 parts by weight to 5 parts by weight,
The latent heat after rotation is large, over 50 cal/g. However, in sample 22 containing 10 parts by weight of formaldehyde,
The latent heat after 1000 cycles drops to 44 cal/g. For samples 23 to 29, the system consisting of CH ₃ CO ₂ Na and H ₂ O containing 56% by weight of CH ₃ CO ₂ Na was kept constant at 100 parts by weight, formaldehyde at 0.5 parts by weight, and paraffin at 1 part by weight. The amount of PVA was varied from 0 parts by weight to 30 parts by weight.
In sample 23, which does not contain PVA, the latent heat at the first time is as high as 58 cal/g, but after 100 times it is 45 cal/g.
g, decreases to 34 cal/g after 1000 times. PVA
In sample 24 containing 0.1 part by weight, the latent heat after 1000 cycles is 43 cal/g, which is considerably larger than sample 23. Samples 25 to 27 containing PVA in a range of 0.5 parts by weight to 10 parts by weight had a large latent heat of 50 cal/g or more after 1000 cycles. However, PVA
For sample 29 mixed with 30 parts by weight, the latent heat after 1000 cycles is
It becomes 43 cal/g, which is considerably smaller than that of sample 26. In Samples 30 and 31, commercially available liquid paraffin was used as the paraffin, but one with a melting point above room temperature was used. There is almost no difference in latent heat from when liquid paraffin is used. Samples 32 and 33 have a degree of polymerization of PVA.
1500 and about 2000. In this case too, the latent heat is PVA with a degree of polymerization of 500
There is almost no difference from the case of using . As shown above, CH ₃ CO ₂ Na is 53-69% by weight.
By mixing PVA, formaldehyde, and paraffin as thickeners in a system consisting of CH ₃ CO ₂ Na and H ₂ O containing within the range of A heat storage material having stable performance that does not change can be obtained. The desirable composition is the composition range marked with a circle in Table 2, that is, CH ₃ CO ₂ Na
and H ₂ O, 0.5 parts by weight of PVA
-20 parts by weight, formaldehyde in an amount of 0.1 to 5 parts by weight, and paraffin in an amount of 0.1 to 5 parts by weight. By the way, in the thickener in the present invention,
PVA crosslinks with each other under the action of formaldehyde and is dispersed in the heat storage material melt, increasing the viscosity of the heat storage material melt and preventing precipitation of CH ₃ CO ₂ Na. Paraffin is thought to work at the interface between the heat storage material melt and PVA, preventing the melt and PVA from separating as CH ₃ CO ₂ Na・3H ₂ O melts and solidifies. It will be done. Effects of the Invention As described above, the present invention provides _CH3CO2Na and _H2O containing _CH3CO2Na in a range of 53% to 69% _by weight _.
As a thickener to prevent phase separation in a system consisting of
Since it is a heat storage material that is a mixture of PVA, formaldehyde, and paraffin, the amount of heat storage does not change even after repeated heat storage and heat release, and it has extremely stable performance. Therefore, the present invention is applicable to all applications that utilize heat storage, including heat storage devices for air conditioning.

Claims (1)

[Claims] 1. A system consisting of sodium acetate and water containing sodium acetate (CH ₃ CO ₂ Na) in the range of 53 to 69% by weight, polyvinyl alcohol, as a thickener,
A heat storage material characterized by being a mixture containing formaldehyde and paraffin. 2. 0.5 to 20 parts by weight of polyvinyl alcohol, 0.1 to 5 parts by weight of formaldehyde, and 0.1 to 5 parts by weight of paraffin are added and mixed to 100 parts by weight of a system consisting of sodium acetate and water. A heat storage material according to claim 1.