Controllable low-temperature composite phase change material of binary inorganic hydrated salt based on sodium sulfate decahydrate and preparation method of controllable low-temperature composite phase change material

Abstract

The invention discloses a controllable low-temperature composite phase change material of binary inorganic hydrated salt based on sodium sulfate decahydrate and a preparation method of the controllable low-temperature composite phase change material, and relates to the technical field of cold storage. According to the material, sodium sulfate decahydrate is used as a main phase change material, magnesium chloride hexahydrate, zinc nitrate hexahydrate and the like are combined as binary inorganic hydrated salt phase change materials, and a nucleating agent, a thickening agent, a cooling agent and a supporting material are added. The invention has obvious innovation. In a material system, sodium sulfate decahydrate is used as a main body and matched with binary inorganic hydrated salt, the phase change temperature is regulated and controlled in an accurate proportion, and the problems of phase separation and supercooling are solved. The preparation method comprises the following steps: mixing the inorganic hydrated salt with the additive, grinding, magnetically stirring, heating and carrying out vacuum adsorption to prepare the composite phase change material, and blending to obtain the composite material with the required temperature, the composite material is safe and stable, has good thermal conductivity and high phase change latent heat, can accurately control the temperature, meets the requirements of the fields of food, fresh food, medicine, chemical industry and the like in cold-chain transportation, and has wide application prospects. And the transportation efficiency and the product quality are obviously improved.

Description

Technical Field

[0001] The invention relates to the field of cold storage technology, in particular to a controllable low-temperature composite phase change material based on a binary inorganic hydrated salt of sodium sulfate decahydrate and a preparation method thereof. Background Art

[0002] With the development of globalization and e-commerce, cold chain transportation has become increasingly critical in the fields of food, medicine, and chemicals. The quality and safety of low-temperature-sensitive items such as fresh food, vaccines, special chemical raw materials, and medicines are highly dependent on precise cold chain transportation. However, the current low-temperature cold storage has problems such as unstable temperature control, low energy efficiency, and high cost, which hinders the development of the industry.

[0003] Different single inorganic phase change materials are used in different temperature ranges of cold chain transportation: calcium chloride hexahydrate is commonly used at 2-8℃, sodium chloride brine solution is often used at -18℃, and mixed salt solution of calcium chloride and magnesium chloride is used at -40℃ to -60℃. However, these materials generally have disadvantages such as phase separation, high supercooling, strong corrosiveness, low latent heat of phase change, and poor heat transfer efficiency, which not only affect the efficiency and quality of the cold chain, but also increase equipment maintenance costs and operational risks.

[0004] In contrast, binary inorganic hydrated salts based on sodium sulfate decahydrate have outstanding advantages. Its phase change temperature is adjustable, which can meet different cold chain requirements; its latent heat of phase change is large, which is conducive to temperature stability; its supercooling degree is low, and its phase change is reliable; its phase separation phenomenon is reduced, its chemical stability is enhanced, and it can be stored for a long time and reused; its cost is low, which is convenient for large-scale application and reduces the overall cold chain cost.

[0005] Sodium sulfate decahydrate has a high latent heat of phase change, and can be adjusted with magnesium chloride hexahydrate to provide stable thermal energy storage and release within the required temperature range. In addition, after the two are mixed to form a eutectic system, they can effectively solve the problem of phase separation and supercooling of single salt hydrates in practical applications, thereby improving the thermal stability and reliability of phase change materials. At the same time, as inorganic salts, they not only have excellent thermal conductivity and low cost, but also have the characteristics of environmental protection and non-toxicity, which are suitable for large-scale application in cold chain transportation.

[0006] The binary inorganic hydrated salt composite phase change material adopted in the present invention can provide precise temperature control in a cold chain transportation environment at the required temperature, reduce energy consumption during cold chain transportation, reduce operating costs, improve transportation efficiency, and ensure comprehensive improvement of the cold chain transportation industry in terms of refinement, environmental protection and economy. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a controllable low-temperature composite phase change material based on a binary inorganic hydrated salt of sodium sulfate decahydrate and a preparation method thereof. The present invention aims to solve the problems of inaccurate temperature control and unstable quality level of cold storage products in the cold chain transportation industry.

[0008] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for preparing a controllable low-temperature composite phase change material based on a binary inorganic hydrated salt of sodium sulfate decahydrate, comprising the following steps:

[0009] (1) Compounding of two inorganic hydrated salts and four additives

[0010] Two inorganic hydrated salts, a cooling agent, a thickener and a nucleating agent were weighed according to the mass ratio, mixed and placed in a beaker, and placed in an oil bath at 50-70° C. for magnetic stirring for 2 hours to fully dissolve the components; then cooled to room temperature and placed in a refrigerator for cooling for 12 hours to obtain an inorganic eutectic material.

[0011] (2) Composite phase change material and supporting material

[0012] The inorganic eutectic material obtained in step (1) is heated to 50-70°C to melt it, and then the support material is added according to the mass ratio, and adsorbed under a vacuum state of -0.1 mPa for 5 minutes; then, it is stirred at room temperature for 30 minutes; finally, the conical flask is placed in an ultrasonic instrument for 10 minutes, cooled to room temperature and placed in a refrigerator to absorb cold energy, and finally the inorganic eutectic material is adsorbed and wrapped by the expanded graphite to obtain a final composite material, and the effect is as follows: Figure 2 shown.

[0013] Preferably, the two inorganic hydrated salts in step (1) are any one of sodium sulfate decahydrate and magnesium chloride hexahydrate, zinc nitrate hexahydrate, disodium hydrogen phosphate dodecahydrate, magnesium sulfate heptahydrate, and potassium aluminum sulfate dodecahydrate.

[0014] Preferably, the two inorganic hydrated salts in step (1) are sodium sulfate decahydrate and magnesium chloride hexahydrate.

[0015] Preferably, in step (1), the ratio of sodium sulfate decahydrate to magnesium chloride hexahydrate is (7-8.5): (1.5-3).

[0016] Preferably, step (1) is composed of the following raw materials in parts by weight: 60-70 parts of phase change material, 5-10 parts of cooling agent, 5-10 parts of thickener, 5-10 parts of nucleating agent, and 10-20 parts of supporting material.

[0017] Preferably, the cooling agent in step (1) is any two of potassium chloride, ammonium chloride and sodium chloride, with a mass ratio of 1:1.

[0018] Preferably, the thickener in step (1) is any one of sodium carboxymethyl cellulose, polyvinyl alcohol, polyacrylamide and gelatin.

[0019] Preferably, the nucleating agent in step (1) is any one of borax, calcium chloride and sodium titanate.

[0020] Preferably, in step (2), the supporting material is expanded graphite, and the ratio of the inorganic eutectic material to the supporting material is 4:1.

[0021] Preferably, the rate of magnetic stirring in step (1) is 800-1000 r / min.

[0022] Preferably, the magnetic stirring rate in step (2) is 800 to 1500 r / min.

[0023] The present invention provides a low-temperature composite phase change material based on binary inorganic hydrated salt and a preparation method thereof. It has the following beneficial effects:

[0024] 1. Compared with other common cold storage products, the quality of thermal insulation is stable;

[0025] 2. Compared with other common cold storage products, the inorganic hydrated salt phase change composite material of the present invention has a longer constant temperature time;

[0026] 3. The compounding process is simple. After simple proportion grinding and mixing, physical mixing is carried out in an oil bath pot. The product can be obtained after being placed in a refrigerator at room temperature to absorb cold energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a flow chart of composite phase change materials;

[0029] Figure 2 This is the SEM image of expanded graphite as a support material to adsorb and encapsulate inorganic eutectic materials;

[0030] Figure 3 Schematic diagram of the phase change temperature test of expanded graphite as a supporting material to adsorb and encapsulate inorganic eutectic materials. DETAILED DESCRIPTION

[0031] The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples within the scope not exceeding the gist of the present invention.

[0032] Embodiment 1:

[0033] like Figure 1 As shown, the embodiment of the present invention provides a method for preparing a controllable low-temperature composite phase change material based on a binary inorganic hydrated salt of sodium sulfate decahydrate, comprising the following steps:

[0034] 1. Calcium chloride is used as nucleating agent. Polyacrylamide is used as thickener, potassium chloride and ammonium chloride are used as cooling agents, and the mass ratio of the two is strictly 1:1.

[0035] 2. Weigh 60 g of sodium sulfate decahydrate, 15 g of magnesium chloride hexahydrate, 5 g of potassium chloride, 5 g of ammonium chloride, 5 g of polyacrylamide and 5 g of calcium chloride according to the mass ratio, mix them and place them in a beaker, put them in an oil bath at 50-70°C and stir them magnetically for 2 hours to fully dissolve the components; then cool them to room temperature and place them in a refrigerator to cool for 12 hours to obtain an inorganic eutectic material.

[0036] 3. The inorganic eutectic material obtained in 2 was heated to 50-70°C to melt it, 5 g of expanded graphite was added, and adsorbed under a vacuum state of -0.1 mPa for 5 min; then, it was stirred at room temperature for 30 min; finally, the conical flask was placed in an ultrasonic instrument for 10 min, cooled to room temperature and placed in a refrigerator to absorb cold energy, and the final composite material was obtained. The scanning electron microscopy of the composite material was as follows: Figure 2 As shown. Figure 3 As shown, the phase change temperature of the final test is in the range of 10 to 15°C, which is suitable for the transportation temperature of most cold storage products.

[0037] Embodiment 2:

[0038] The embodiment of the present invention provides a method for preparing a controllable low-temperature composite phase change material based on a binary inorganic hydrated salt of sodium sulfate decahydrate, comprising the following steps:

[0039] 1. In this embodiment, sodium sulfate decahydrate and potassium aluminum sulfate dodecahydrate are selected as binary inorganic hydrated salts in a ratio of 8.5:1.5, and ammonium chloride and ethylene glycol are selected as cooling agents.

[0040] 2. Weigh 64 g of sodium sulfate decahydrate, 11 g of potassium aluminum sulfate dodecahydrate, 5 g of ammonium chloride, 5 g of ethylene glycol, 5 g of sodium carboxymethyl cellulose and 5 g of borax according to the mass ratio, mix them and place them in a beaker, put them in an oil bath at 50-70°C and stir them magnetically for 2 hours to fully dissolve the components; then cool them to room temperature and place them in a refrigerator to cool for 12 hours to obtain an inorganic eutectic material.

[0041] 3. Heat the inorganic eutectic material obtained in 2 to 50-70°C to melt it, add 10 g of expanded graphite, and adsorb it under a vacuum state of -0.1 mPa for 5 minutes; then, stir it at room temperature for 30 minutes; finally, place the conical flask in an ultrasonicator for 10 minutes, cool it to room temperature and put it in a refrigerator to absorb cold energy to obtain the final composite material.

[0042] Embodiment three:

[0043] The embodiment of the present invention provides a method for preparing a controllable low-temperature composite phase change material based on a binary inorganic hydrated salt of sodium sulfate decahydrate, comprising the following steps:

[0044] 1. In this embodiment, sodium sulfate decahydrate and disodium hydrogen phosphate dodecahydrate are selected as dibasic inorganic hydrated salts in a ratio of 8:2.

[0045] 2. Weigh 60 g of sodium sulfate decahydrate, 15 g of disodium hydrogen phosphate dodecahydrate, 5 g of ammonium chloride, 5 g of potassium chloride, 5 g of sodium carboxymethyl cellulose and 5 g of borax according to the mass ratio, mix them and place them in a beaker, put them in an oil bath at 50-70°C and stir them magnetically for 2 hours to fully dissolve the components; then cool them to room temperature and place them in a refrigerator to cool for 12 hours to obtain an inorganic eutectic material.

[0046] 3. Heat the inorganic eutectic material obtained in 2 to 50-70°C to melt it, add 10 g of expanded graphite, and adsorb it under a vacuum state of -0.1 mPa for 5 minutes; then, stir it at room temperature for 30 minutes; finally, place the conical flask in an ultrasonicator for 10 minutes, cool it to room temperature and put it in a refrigerator to absorb cold energy to obtain the final composite material.

[0047] Embodiment 4:

[0048] The embodiment of the present invention provides a method for preparing a controllable low-temperature composite phase change material based on a binary inorganic hydrated salt of sodium sulfate decahydrate, comprising the following steps:

[0049] 1. According to the mass ratio, weigh 60g of sodium sulfate decahydrate, 15g of magnesium chloride hexahydrate, 5g of potassium chloride, 5g of ammonium chloride, 5g of sodium polymethylcellulose and 5g of borax, mix them and place them in a beaker, put them in an oil bath pot at 50-70°C and stir them magnetically for 2 hours to fully dissolve the components; then cool them to room temperature and place them in a refrigerator to cool for 12 hours to obtain an inorganic eutectic material.

[0050] 2. Heat the inorganic eutectic material obtained in 2 to 50-70°C to melt it, add 5 g of expanded graphite, and adsorb it under a vacuum state of -0.1 mPa for 5 minutes; then, stir it at room temperature for 30 minutes; finally, place the conical flask in an ultrasonicator for 10 minutes, cool it to room temperature and put it in a refrigerator to absorb cold energy to obtain the final composite material.

[0051] These four implementation methods further expand the application scope and performance of controllable low-temperature composite phase change materials based on binary inorganic hydrated salt of sodium sulfate decahydrate by adjusting different components, proportions or preparation conditions, and provide more ideas and possibilities for technological research and development in related fields.

[0052] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A controllable low-temperature composite phase change material based on a binary inorganic hydrated salt of sodium sulfate decahydrate, comprising a phase change material, a nucleating agent, a thickener, a cooling agent and a supporting material, characterized in that: The phase change material comprises a main body and an auxiliary material, wherein the main body is sodium sulfate decahydrate.

2. The low temperature composite phase change material according to claim 1, characterized in that: The auxiliary materials include any one of magnesium chloride hexahydrate, zinc nitrate hexahydrate, disodium hydrogen phosphate dodecahydrate, magnesium sulfate heptahydrate, and potassium aluminum sulfate dodecahydrate.

3. The low temperature composite phase change material according to claim 1, characterized in that: The ratio of the main material to the auxiliary material in the phase change material is (7-8.5): (1.5-3).

4. A low-temperature composite phase change material based on binary inorganic hydrated salt, characterized in that: The invention is composed of the following raw materials in parts by weight: 60-70 parts of phase change material, 5-10 parts of cooling agent, 5-10 parts of thickener, 5-10 parts of nucleating agent and 10-20 parts of supporting material.

5. The low temperature composite phase change material according to claim 1, characterized in that: The cooling agent includes any two of potassium chloride, ammonium chloride and sodium chloride.

6. The low temperature composite phase change material according to claim 1, characterized in that: The thickener is any one of sodium carboxymethyl cellulose, polyvinyl alcohol, polyacrylamide and gelatin.

7. The low temperature composite phase change material according to claim 1, characterized in that: The nucleating agent is any one of borax, calcium chloride and sodium titanate.

8. The method for preparing a low-temperature composite phase change material according to claim 1, characterized in that: The following steps are included: (1) weighing sodium sulfate decahydrate, magnesium chloride hexahydrate, a cooling agent, a thickener and a nucleating agent according to a mass ratio, mixing them and placing them in a beaker, placing them in an oil bath pot, and magnetically stirring them at a certain temperature and a certain number of revolutions for a certain period of time to fully dissolve the components; then cooling them to room temperature, and placing them in a refrigerator to cool, to obtain an inorganic eutectic material; (2) The inorganic eutectic material obtained in step (1) is heated until it melts, and then a supporting material is added according to a mass ratio. After adsorbing for a certain period of time under a vacuum state, the material is stirred at a certain number of revolutions at room temperature. Finally, the conical flask is placed in an ultrasonicator for a certain period of time, cooled to room temperature and placed in a refrigerator to absorb cold energy. Finally, the inorganic eutectic material is adsorbed and wrapped by the expanded graphite to obtain a final composite material.

9. The method for preparing a low-temperature composite phase change material according to claim 8, characterized in that: The supporting material is expanded graphite.

10. The method for preparing a low-temperature composite phase change material according to claim 8, characterized in that: The mass ratio of the inorganic eutectic material to the supporting material is 4:1.

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