WO2024060036A1

WO2024060036A1 - Phase change material having phase change temperature of 2-8°c and preparation method therefor

Info

Publication number: WO2024060036A1
Application number: PCT/CN2022/120015
Authority: WO
Inventors: 周军辉; 汤弢
Original assignee: 纯钧新材料(深圳)有限公司
Priority date: 2022-09-20
Filing date: 2022-09-20
Publication date: 2024-03-28

Abstract

A phase change material having a phase change temperature of 2-8°C and a preparation method therefor. The phase change material comprises the following components in parts by mass: 30-50 parts of phase change cold storage agent, 0.3-3 parts of nucleating agent, 0.5-8 parts of thickening agent, 0.1-1 parts of crystal form modifier, 1-5 parts of performance optimizer and 35-70 parts of water. The phase change cold storage agent comprises at least two of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, barium hydroxide, calcium hydroxide, ammonia water, potassium bicarbonate, sodium bicarbonate, potassium chloride, sodium chloride, barium chloride, potassium nitrate, sodium acetate, sodium sulfate, and disodium hydrogen phosphate. The crystal form improver is at least one of diatomite, activated clay, and soluble starch. The preparation method comprises: adding the phase change cold storage agent into water, adding the nucleating agent, the crystal form improver, the performance optimizer, and the thickening agent, and uniformly stirring to obtain the phase change material. The obtained phase change material has phase change latent heat greater than 260 kJ/kg, a thermal conductivity coefficient greater than 1.1 W/(m.K), a density greater than 1.6 g/cm3, a volume expansion ratio less than 0.5%, a supercooling degree less than 1°C, and good cyclic stability performance, and the preparation process is simple.

Description

Phase change material with phase change temperature of 2~8°C and preparation method thereof

Technical field

The present invention relates to the technical field of phase change materials, and in particular to a phase change material with a phase change temperature of 2 to 8°C and a preparation method thereof.

Background technique

With the rapid development of modern logistics and the increasing demand for cold chain pharmaceuticals, pharmaceutical cold chain logistics has also received more attention. In particular, during the cold chain transportation of medicines in the 2~8°C range, the temperature and fluctuation range need to be strictly controlled to store or transport medicines, vaccines, blood products and other items to ensure their quality and effectiveness. However, the demand for medical cold chain transportation in the 2~8℃ range is huge and the cost is too high. Therefore, reducing the cost of medical cold chain transportation in the 2~8℃ range has great economic benefits.

At present, inorganic hydrated salts and organic phase change materials are often used in pharmaceutical cold chain transportation phase change materials. However, inorganic hydrated salts have shortcomings such as phase separation and easy leakage, while organic phase change materials also have shortcomings such as low latent heat and flammability. In the existing technology, alcohol phase change material matrix is also used. However, it has the characteristics of low density, low latent heat of phase change per unit volume, low thermal conductivity, high volume expansion rate and easy leakage; low density, low phase change per unit volume, etc. The light weight of the material leads to low latent heat of phase change per unit volume, so in practical applications, the holding time under the same conditions is short; the high volume expansion rate will cause the ice pack (or other fixed container) to be filled with the same volume. There are fewer phase change materials, which reduces the holding time; and the higher the volume expansion rate, the easier it is to cause problems such as bulging, expansion, or even rupture of the ice row (or other containers), and it is prone to leakage and other problems.

technical problem

The technical problem to be solved by the present invention is to provide a phase change material with a phase change temperature of 2 to 8°C and a preparation method thereof in view of the shortcomings of the existing technology. The phase change material has good stability, low material cost, and a preparation process Simple, with high density, low expansion rate, high latent heat of phase change, high thermal conductivity, good effect after multiple cycles, and long cycle life.

Technical solutions

The technical solution adopted by the present invention to solve the technical problem is: a low-temperature phase change material with a phase change temperature of 2 to 8°C, including the following components in parts by mass: 30 to 50 parts of phase change coolant, nucleating agent 0.3~3 parts, 0.5~8 parts of thickener, 0.1~1 part of crystal modifier, 1~5 parts of performance optimizer, 35~70 parts of water;

The phase change cold storage agent includes potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, barium hydroxide, calcium hydroxide, ammonia water, potassium bicarbonate, sodium bicarbonate, potassium chloride, sodium chloride, barium chloride , at least two of potassium nitrate, sodium acetate, sodium sulfate, and disodium hydrogen phosphate;

The crystal form modifier is at least one of diatomite, activated clay, soluble starch, fumed silica, viscose fiber, acetate fiber, polyester, acrylic fiber, spandex, polyvinyl chloride, glass fiber, and asbestos;

The performance optimizer has a spherical structure, and the outer surface of the performance optimizer is covered with a positive ion layer.

Furthermore, in the phase change cold storage agent, it is preferred that the crystal form modifier has a particle size of 20 to 100 μm.

Further, in the phase change cold storage agent, it is preferable that the nucleating agent is nano carbon powder, graphite powder, nano zinc oxide, nano aluminum oxide, nano copper, nano silicon nitride, carbon nanotube, carboxylated polyethylene. at least one type of carbon nanotube.

Furthermore, in the phase-change refrigerant, the particle size of the nucleating agent is preferably 10 to 200 μm.

Further, in the phase change cold storage agent, it is preferred that the thickener is polyacrylamide, sodium polyacrylate, sodium carboxymethylcellulose, sodium hydroxymethylcellulose, xanthan gum, and guar gum. , at least one of activated clay, gelatin, attapulgite, gum arabic, pectin, agar, tamarind gum, β-cyclodextrin, sodium carboxymethyl starch, and hydroxypropyl starch.

Furthermore, in the phase change cold storage agent, it is preferred that the thickener has a particle size of 20 to 100 μm. Further, in the phase change cold storage agent, it is preferred that the performance optimization agent is at least one of gold sol, silver sol, copper sol, and aluminum sol.

Furthermore, in the phase-change refrigerant, the particle size of the performance optimizer is preferably 1 nm to 100 nm.

Further, in the phase change cool storage agent, it is preferred that the positive ion layer is an H ⁺ layer.

A method for preparing the above-mentioned low-temperature phase change material with a phase change temperature of 2 to 8°C, including the following steps:

S1. Take the phase change cold storage agent in proportion, slowly add it to water to dissolve, stir and mix evenly, and obtain the first mixed solution;

S2. Add the nucleating agent to the first mixed solution, stir and mix, stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform and fluid, to obtain the second mixed solution;

S3, adding a crystal form modifier to the second mixed solution, stirring and mixing, and stopping stirring when the crystal form modifier is completely dissolved and the solution is in a uniform fluid state, to obtain a third mixed solution;

S4. Add the performance optimizer to the third mixed solution, stir and mix, stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid, to obtain the fourth mixed solution;

S5. Add the thickener to the fourth mixed solution, stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes uniform and fluid, to obtain a phase change material.

Further, in the preparation method of the phase change coolant, preferably in step S1, the stirring temperature is 25~35°C, the stirring rate is 400~600rpm, and the stirring time is 1~2h.

Further, in the preparation method of the phase change cool storage agent, preferably in step S2, the stirring temperature is 25~35°C, the stirring rate is 400~600rpm, and the stirring time is 1~2h.

Further, in the preparation method of the phase change coolant, preferably in step S3, the stirring temperature is 25~35°C, the stirring rate is 400~600rpm, and the stirring time is 1~2h.

Further, in the preparation method of the phase change coolant, preferably in step S4, the stirring temperature is 25~35°C, the stirring rate is 400~600rpm, and the stirring time is 1~2h.

Further, in the preparation method of the phase change coolant, preferably in step S5, the stirring temperature is 25-35°C, the stirring rate is 600~800rpm, and the stirring time is 2~4h.

beneficial effects

Beneficial effects of the present invention: The present invention provides a low-temperature phase change material with a phase change temperature of 2-8°C and a preparation method thereof. The phase change material of the present invention comprises a phase change refrigerant, a nucleating agent, a thickener, a crystal modifier, a performance optimizer, and water. A variety of inorganic salts selected from potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, barium hydroxide, calcium hydroxide, ammonia water, potassium bicarbonate, sodium bicarbonate, potassium chloride, sodium chloride, barium chloride, potassium nitrate, sodium acetate, sodium sulfate, and disodium hydrogen phosphate are used as phase change refrigerants, which make up for the problems of too small or too large phase change temperature, reduced phase change latent heat, and low cycle stability when a single phase change refrigerant is used. In addition, adding a crystal modifier to the system can well control the crystal size, prevent excessive crystal growth, make the low eutectic mixture crystals small and uniform, and can also increase the phase change temperature of the phase change refrigerant, so that the phase change temperature is increased from 3°C to about 5°C. More importantly, the crystal modifier selected by the present invention The modifier has a large specific surface energy, good small crystal adsorption, and can promote crystal growth. It has an excellent adsorption effect on the characteristics of the fine grains of the phase change refrigerant selected by the present invention, and forms a network structure after adsorption, which enhances the binding force between the ions of the phase change material. When a solid-liquid phase change occurs, more energy is required to destroy this network structure, thereby significantly increasing the latent heat of the phase change and greatly enhancing the cycle stability; the performance optimizer with a spherical structure added to the system can be connected with the network structure formed by the crystal modifier and the phase change refrigerant to form a three-dimensional layered super-large network structure, which can significantly improve the binding force of the network structure; in the process of solid-liquid phase change, a very large energy is required to destroy the three-dimensional layered structure, which can greatly improve the cycle stability performance of the material system, reduce the rate of change of the phase change temperature before and after the cycle, and keep the phase change temperature stable; the latent heat of the phase change material can be significantly increased. Adding a nucleating agent into the system can play a nucleating role, which can greatly reduce the supercooling degree, and at the same time can significantly improve the thermal conductivity of the material system, thereby increasing the heat exchange rate, controlling the temperature more quickly, and obtaining a phase change material with high thermal conductivity and low supercooling degree; adding a thickener into the system can play a thickening role, prevent phase stratification, and improve the cyclic stability performance; the phase change material of the present invention has high thermal conductivity, high density, low expansion rate, high phase change latent heat, good stability, low material cost, safety and non-toxicity, and a simple preparation process. The phase change temperature of the phase change material of the present invention is 2~8°C, the phase change latent heat is >260kJ/kg, the thermal conductivity is >1.1W/(m.K), the density is >1.6g/cm3, the volume expansion rate is <0.5%, and the supercooling degree is <1°C. After 200 cycles, it still has a good phase change latent heat.

Embodiments of the invention

A low-temperature phase change material with a phase change temperature of 2 to 8°C, including the following components by mass: 30 to 50 parts of phase change coolant, 0.3 to 3 parts of nucleating agent, 0.5 to 8 parts of thickener, Crystal form improver 0.1~1 part, performance improver 1~5 parts, water 35~70 parts; phase change coolant includes potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, barium hydroxide, calcium hydroxide , ammonia, at least two of potassium bicarbonate, sodium bicarbonate, potassium chloride, sodium chloride, barium chloride, potassium nitrate, sodium acetate, sodium sulfate, and disodium hydrogen phosphate; the crystal form modifier is diatomite , at least one of activated clay, soluble starch, fumed silica, viscose fiber, acetate fiber, polyester, acrylic fiber, spandex, chlorine fiber, glass fiber, and asbestos; the performance optimizer has a spherical structure, except for the performance optimizer The surface is covered with a positive ion layer.

The invention provides a low-temperature phase change material with a phase change temperature of 2 to 8°C and a preparation method thereof. The phase change material of the invention includes a phase change cold storage agent, a nucleating agent, a thickener, a crystal form modifier, and water. , with potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, barium hydroxide, calcium hydroxide, ammonia, potassium bicarbonate, sodium bicarbonate, potassium chloride, sodium chloride, barium chloride, potassium nitrate, acetic acid A variety of inorganic salts such as sodium, sodium sulfate, and disodium hydrogen phosphate are used as phase change coolant, which makes up for the problems of too small or too large phase change temperature, reduced latent heat of phase change, and reduced cycle stability when using a single phase change coolant. ; And adding a crystal modifier to the system can well control the crystal particle size, prevent the crystal from excessive growth, make the crystals of the eutectic mixture fine and uniform, and also increase the phase change temperature of the phase change coolant, so that the phase change temperature changes from 3°C is increased to about 5°C. More importantly, the crystal form modifier selected in the present invention has a large specific surface energy, has good adsorption of small crystals, and can promote crystal growth. For the phase change cold storage agent selected in the present invention The characteristics of the fine grains have excellent adsorption, and after adsorption, they form a network structure, which enhances the binding force between the ions of the phase change material. When a solid-liquid phase change occurs, more energy is required to destroy this network. structure, thus significantly increasing the latent heat of phase change and greatly enhancing cycle stability; the performance optimizer includes a basic atomic nucleus and a negative ion layer coating the basic atomic nucleus. Adding a spherical structure performance optimizer to the system can be combined with the crystal form modifier The network structure formed by the phase change cold storage agent is connected together to form a three-dimensional layered super large network structure, which can significantly improve the binding force of the network structure; during the solid-liquid phase change process, a very large amount of energy is required to destroy the three-dimensional The layered structure can greatly improve the cyclic stability of the material system, reduce the change rate of the phase change temperature before and after cycles, and keep the phase change temperature stable; it can significantly increase the latent heat of phase change of the phase change material. Adding a nucleating agent to the system can play a nucleating role, which can significantly reduce the degree of supercooling. It can also significantly increase the thermal conductivity of the material system, thereby increasing the heat exchange rate and controlling temperature more quickly, resulting in high thermal conductivity and low temperature. Supercooled phase change material; adding a thickener to the system can play a thickening effect, prevent phase stratification, and improve cycle stability; the phase change material of the present invention has high density, low expansion rate, and low phase change latent heat High, good stability, low material cost, safe and non-toxic, and simple preparation process. The phase change temperature of the phase change material of the present invention is 2~8°C, the latent heat of phase change is >260 kJ/kg, and the thermal conductivity is >1.1W/( m.K), density >1.6 g/cm3, volume expansion rate <0.5%, low supercooling <1°C, and still has good latent heat of phase change after 200 cycles.

Furthermore, the preferred particle size of the crystal form modifier is 20 to 100 μm. The purpose of controlling the particle size is mainly to control the dispersion effect of the crystal form modifier in the solution system, and to better control the crystal particle size. If the crystal grains are too large, it is not conducive to dispersion and dissolution in the solution. If the crystal grains are too small, the effect of controlling the crystal particle size will be reduced. Therefore, controlling the particle size is mainly to better exert the effect of the crystal form modifier.

Further, it is preferred that the nucleating agent is at least one of nanocarbon powder, graphite powder, nanozinc oxide, nanoalumina, nanocopper, nanosilicon nitride, carbon nanotubes, and carboxylated multi-walled carbon nanotubes. Due to the non-uniform nucleation mechanism, adding a nucleating agent to the phase change system of the present invention can effectively reduce the supercooling degree of the phase change material, and this requires the crystal structure characteristics and lattice between the nucleating agent and the phase change cold storage agent. Parameter size, physical properties, etc. are matched, and thickeners and crystal form modifiers are added, so the particle size of the nucleating agent is controlled to be 10 μm ~ 200 μm. The nucleating agent is used to play a role in the solidification process of phase change materials. It can act as a crystal nucleator, promote crystal growth, and reduce the barrier to nucleation and growth. The particle size within this range can act as a crystal nucleator during the solidification process, promote crystal growth, and reduce the barrier to nucleation and growth. It can also be effective. Reduce the degree of supercooling of the phase change material; the particle size is too small and it is difficult to function as a crystal nucleus for nucleation and growth. It cannot significantly reduce the crystallization driving force, and the effect of reducing the degree of supercooling is not good; the particle size is too large and the crystal cannot be crystallized during the crystallization process. It grows on the surface of large grains, so it cannot play the role of crystal nucleation, cannot reduce the crystallization driving force at all, and cannot reduce the degree of supercooling; and the nucleating agent used above is a high thermal conductivity material, and the high thermal conductivity material is used as Nucleating agents can increase the thermal conductivity of the phase change material system, thereby increasing the heat exchange rate and enabling faster temperature control.

Further, preferred thickeners are polyacrylamide, sodium polyacrylate, sodium carboxymethylcellulose, sodium hydroxymethylcellulose, xanthan gum, guar gum, activated clay, gelatin, attapulgite, and gum arabic. , pectin, agar, tamarind gum, β-cyclodextrin, sodium carboxymethyl starch, and at least one of hydroxypropyl starch; in the present invention, adding a thickening agent to the system can play a thickening effect, so that The solid particles or crystal nuclei of the phase change coolant in the system can be evenly distributed in the solution without being affected by gravity and cause stratification. This effectively improves the phase separation problem of phase change materials, prevents phase stratification, and improves cycle stability. The thickener forms a network or chain structure through links with raw material molecules, especially links with water molecules, thereby increasing the viscosity of the system; if the particle size of the thickener is too large or too small, it will be detrimental to The phase change material forms a network or chain structure and the thickening effect is reduced, so the particle size of the thickener is controlled to 20~100 μm.

Further, it is preferred that the performance optimizer is at least one of gold sol, silver sol, copper sol, and aluminum sol. The performance optimizer (gold sol, silver sol, copper sol, aluminum sol) itself includes a basic atomic nucleus (atomic gold, or atomic silver, or atomic aluminum, or atomic copper) and a surrounding negative ion layer to further optimize performance. The outermost layer of the agent is coated with a positive ion layer, such as hydrogen ions, or Na ⁺ , K ⁺ , Ca2 ⁺ , Ba ²⁺ , etc. The positive ions except H ⁺ are preferably mixed with those contained in the phase change coolant. If the ions are the same or in the same family, the negative ion layer and the positive ion layer will not react. Opposites of positive and negative ions attract each other, but the two are a dynamic balance process. For the specific H ⁺ layer, the performance optimizer can be optimized through acidic solutions such as hydrochloric acid and sulfuric acid. Acid washing makes the negative ion outer layer of the performance optimizer coated with an H ⁺ ion layer, and H ⁺ is dispersed in the solution, taking the form of small spherical particles; in a specific embodiment, 100 ml of 1% gold sol aqueous solution is heated to boiling , add 0.7~1ml of 1% trisodium citrate (Na3C6H5O7·2H2O) aqueous solution under constant temperature heating and stirring, heat to 100°C under vacuum for 30 minutes, cool and adjust to 1% solubility with distilled water, and then add it to the gold sol The outer layer of negative ions is coated with a H+ ion layer, and H+ is dispersed in the solution. First, the crystal form modifier can adsorb the phase change coolant to form a network structure. The phase change coolant is mainly alkaline and can form a strong adsorption binding force with the performance optimizer with H+ layer. Then, because the performance optimizer is spherical, particles, so the previously formed network structure can be formed into a larger three-dimensional layered structure laterally and longitudinally, which can significantly improve the binding force of the network structure; very large energy is required to destroy the three-dimensional layer during the solid-liquid phase change process. The structure can greatly improve the cyclic stability of the material system, reduce the change rate of the phase change temperature before and after cycles, keep the phase change temperature stable, and significantly increase the latent heat of phase change of the phase change material. If the particle size of the performance optimizer is too large or too small, it will not be conducive to the formation of a three-dimensional layered ultra-large network structure and affect the stability of the phase change material. Therefore, the particle size of the performance optimizer is controlled to be 1nm~100nm.

The nucleating agent used in the present invention is mainly carbon powder, graphite powder, nano-alumina and other materials with high thermal conductivity, so it can significantly improve the thermal conductivity of the phase change material.

The phase change coolant material of the present invention adopts inorganic materials which have high density, and the proportion in the entire phase change material system is also very high. It can increase the density of the phase change material system of the present invention, which is roughly the organic phase change. It is about 2 times the density of the material. The high density of the phase change material within the unit volume results in a high phase change enthalpy per unit volume. The latent heat of phase change per unit volume is about 430J/ml. Therefore, in practical applications, the holding time under the same conditions is longer. , the latent heat per unit mass of the phase change material of the present invention is about 260kJ/kg; secondly, the phase change cool storage agent selected in the present invention is an inorganic salt material, and the connection between the ions in the aqueous solution mainly exists in the form of ionic bonds. During liquid phase change, more energy is required to destroy ionic bonds, so the latent heat of phase change is high; furthermore, the crystal form modifier added in the present invention has good adsorption to the fine crystal grains of the phase change cold storage agent selected in the present invention. function and form a network structure, making the binding force between ions stronger. When solid-liquid phase change occurs, greater energy is required to destroy this network structure; in summary, the phase change latent heat of the phase change material of the present invention high.

The type and proportion of the phase change cool storage agent selected in the present invention have excellent cycle stability; secondly, the selected nucleating agent, thickener, and crystal form modifier have a strengthening effect on the performance of the entire material system; furthermore, The crystal form modifier added in the present invention has an adsorption effect on the fine crystal grains of the phase change cold storage agent selected in the present invention, and forms a network structure, which can significantly improve the cycle stability of the phase change material. In summary, the phase change material of the present invention has good cycle stability.

A method for preparing the above-mentioned low-temperature phase change material with a phase change temperature of 2-8°C comprises the following steps:

S1. Take the phase change cold storage agent in proportion, slowly add it to water to dissolve, stir and mix evenly, and obtain the first mixed solution.

Further, preferably in step S1, the stirring temperature is 25-35°C, the stirring rate is 400~600rpm, and the stirring time is 1~2h. Controlling the temperature and stirring rate is mainly to accelerate the dissolution of the phase change coolant and stir evenly. The temperature should generally not be too low and should be kept above room temperature. At the same time, the temperature should not be too high to prevent water from evaporating during the stirring process. The purpose of controlling the stirring time is to make the phase change The variable coolant is fully dissolved to form a uniform first mixed solution.

S2. Add a nucleating agent to the first mixed solution, stir and mix, stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform and fluid, to obtain a second mixed solution.

Further, preferably in step S2, the stirring temperature is 25-35°C, the stirring rate is 400~600rpm, and the stirring time is 1~2h. Controlling the temperature and stirring rate is mainly to accelerate the dissolution of the nucleating agent and stir evenly. The temperature should generally not be too low or too high. It is generally maintained at 25-35°C to prevent water from evaporating during the stirring process due to the temperature being too high. At the same time, it can also make The nucleating agent can well reduce the supercooling of the phase change material system, promote crystal growth, and reduce the potential barrier for nucleation growth; the stirring time is controlled to fully dissolve the nucleating agent and form a uniform second mixed solution.

S3. Add the crystal form modifier to the second mixed solution, stir and mix, stop stirring when the crystal form modifier is completely dissolved and the solution becomes uniform and fluid, to obtain a third mixed solution.

Further, preferably in step S3, the stirring temperature is 20~35°C, the stirring speed is 400~600rpm, and the stirring time is 1~2h. The main purpose of controlling the temperature and stirring rate is to accelerate the dissolution of the crystal form modifier and stir evenly. The temperature should generally not be too low or too high. It is generally maintained at 20~35°C to prevent water from evaporating during the stirring process due to the temperature being too high. At the same time, The crystal form modifier has an excellent adsorption effect on the characteristics of the fine crystal grains of the phase change cool storage agent selected in the present invention, and forms a network structure after adsorption, which enhances the binding force between the ions of the phase change material, and when the solid-liquid phase occurs When changing, more energy is required to destroy this network structure, thus significantly increasing the latent heat of phase change and greatly enhancing cycle stability; the stirring time is controlled to fully dissolve the crystal form modifier and form a uniform third mixture. solution.

S4. Add the performance optimizer to the third mixed solution, stir and mix, stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid, to obtain a fourth mixed solution.

Furthermore, preferably in step S4, the stirring temperature is 25-35°C, the stirring rate is 400-600rpm, and the stirring time is 1-2h. The temperature and stirring rate are controlled mainly to accelerate the dispersion of the performance optimizer and stir evenly. The temperature is generally not too low and is generally kept above room temperature; at the same time, the temperature cannot be too high to prevent water from volatilizing during the stirring process. The stirring time is to allow the performance optimizer to fully dissolve and form a uniform fourth mixed solution. Adding a performance optimizer to the system can connect the network structure formed by the crystal form modifier and the phase change material to form a three-dimensional layered super-large network structure, which can significantly improve the binding force of the network structure; in the process of solid-liquid phase change, a very large energy is required to destroy the three-dimensional layered structure, which can greatly improve the cyclic stability of the material system, reduce the rate of change of the phase change temperature before and after the cycle, keep the phase change temperature stable, and significantly increase the phase change latent heat of the phase change material.

Further, preferably in step S5, the stirring temperature is 20-35°C, the stirring rate is 600~800rpm, and the stirring time is 2~4h. The main purpose of controlling the temperature, stirring rate and time is to accelerate the dissolution of the thickener and stir evenly. The temperature should generally not be too low or too high. It is generally maintained at 20-35°C to prevent water from evaporating during the stirring process due to the temperature being too high. It fully dissolves and enhances the viscosity of the phase change system, so that the solid particles or crystal nuclei of the phase change coolant in the solution can be evenly distributed in the system solution without being affected by gravity and causing stratification, effectively improving the phase separation problem of phase change materials.

The following is a detailed description through specific examples:

Example 1

A low-temperature phase change material with a phase change temperature of 2~8°C, including the following mass parts: 45 parts of phase change coolant (35 parts of sodium hydroxide, 10 parts of sodium carbonate), 1.5 parts of nucleating agent ( 1 part of nano-zinc oxide, 0.5 part of carbon nanotube, control particle size about 10 μm), 4 parts of thickening agent xanthan gum (control particle size of about 20 μm), 0.1 part of crystal modifier diatomite (control particle size About 20 μm), 5 parts of performance optimizer gold sol (the outer surface is coated with a positive ion layer, the positive ions are H ⁺ , and the particle size is controlled to be about 1 nm), and 44.4 parts of water. Among them, sodium hydroxide and sodium carbonate can be replaced by potassium carbonate, potassium hydroxide, barium hydroxide, calcium hydroxide, ammonia, potassium bicarbonate, sodium bicarbonate, potassium chloride, sodium chloride, barium chloride, potassium nitrate , sodium acetate, sodium sulfate, and disodium hydrogen phosphate, as long as the total amount of phase change coolant reaches 45 parts; nano zinc oxide and carbon nanotubes can be replaced with nano carbon powder, graphite powder, nano alumina, At least one of nano-copper, nano-silicon nitride, and carboxylated multi-walled carbon nanotubes, as long as the total amount of nucleating agent meets 1.5 parts; xanthan gum can be replaced by polyacrylamide, sodium polyacrylate, carboxylated Sodium methylcellulose, sodium carboxymethylcellulose, guar gum, activated clay, gelatin, attapulgite, gum arabic, pectin, agar, tamarind gum, β-cyclodextrin, carboxymethyl starch At least one of sodium and hydroxypropyl starch, as long as the total amount of thickeners meets 4 parts; diatomite can be replaced with activated clay, soluble starch, fumed silica, viscose fiber, acetate fiber , polyester, acrylic fiber, spandex, chlorine fiber, glass fiber, asbestos, as long as the total amount of crystal modifier meets 0.1 parts; the gold sol can be replaced by silver sol, copper sol, aluminum sol At least one kind, as long as the total amount of gold sol meets 5 parts.

The preparation method comprises the following steps:

S1. Take 35 parts of phase change cold storage agent sodium hydroxide and 10 parts of sodium carbonate in proportion, slowly add 44.4 parts of water to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring rate is 400rpm, the stirring time is 1h, and the first mixture is obtained solution.

S2. Add 1 part of the nucleating agent nano-zinc oxide and 0.5 part of the carbon nanotube to the first mixed solution, stir and mix. Stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 20°C. The speed is 400 rpm, the stirring time is 1 hour, and the second mixed solution is obtained.

S3. Add 0.1 part of the crystal form modifier diatomite into the second mixed solution, stir and mix. Stop stirring when the crystal form modifier is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C and the stirring rate is 400 rpm. The stirring time is 1 hour, and the third mixed solution is obtained.

S4. Add 5 parts of the performance optimizer gold sol into the third mixed solution, stir and mix. Stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C, the stirring rate is 400 rpm, and the stirring time is 1h, the fourth mixed solution was obtained.

S5. Add 4 parts of the thickener xanthan gum to the fourth mixed solution, stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 20°C and the stirring rate is 600 rpm. The stirring time was all 2h, and the phase change material was obtained.

Example 2

A low-temperature phase change material with a phase change temperature of 2~8°C, including the following mass parts: 50 parts of phase change coolant (including 30 parts of potassium hydroxide and 20 parts of potassium carbonate), nucleating agent graphite powder 3 parts (control particle size is about 105 μm), 8 parts thickener polyacrylamide (control particle size is about 60 μm), 1 part crystal modifier activated clay (control particle size is about 60 μm), performance optimizer gold sol 3 parts (the outer surface is covered with a positive ion layer, the positive ions are K ⁺ , and the particle size is controlled to be about 45nm), 35 parts of water.

Its preparation method includes the following steps:

S1. Take 30 parts of phase change cold storage agent potassium hydroxide and 20 parts of potassium carbonate in proportion, slowly add 35 parts of water to dissolve, stir and mix evenly, the stirring temperature is 27°C, the stirring rate is 400rpm, the stirring time is 1h, and the first mixture is obtained solution.

S2. Add 3 parts of nucleating agent graphite powder to the first mixed solution, stir and mix. Stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 27°C, the stirring speed is 500 rpm, and the stirring time is 1.5h, the second mixed solution was obtained.

S3. Add 1 part of the crystal modifier activated clay into the second mixed solution, stir and mix. Stop stirring when the crystal modifier is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 27°C and the stirring rate is 500 rpm. The time is 1.5h, and the third mixed solution is obtained.

S4. Add 3 parts of the performance optimizer gold sol into the third mixed solution, stir and mix. Stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 27°C, the stirring rate is 500 rpm, and the stirring time is 1.5h, the fourth mixed solution was obtained.

S5. Add 8 parts of the thickener polyacrylamide to the fourth mixed solution, stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 27°C, the stirring rate is 700 rpm, and the stirring time For 3h, the phase change material was obtained.

Example 3

A low-temperature phase change material with a phase change temperature of 2 to 8°C, including the following mass parts: 30 parts of phase change coolant (including 20 parts of barium hydroxide and 10 parts of barium chloride), nucleating agent nano 0.3 parts of toner (control particle size is approximately 200 μm), 1 part thickening agent sodium carboxymethyl cellulose (control particle size is approximately 100 μm), 0.1 part crystal modifier soluble starch (control particle size is approximately 100 μm), 1 part of performance optimizer silver sol (the outer surface is coated with a positive ion layer, the positive ion is Ba ²⁺ , and the particle size is controlled to about 100 nm), 67.6 parts of water.

Its preparation method includes the following steps:

S1. Take 20 parts of phase change cold storage agent barium hydroxide and 10 parts of barium chloride in proportion, slowly add 67.6 parts of water to dissolve, stir and mix evenly, the stirring temperature is 35°C, the stirring rate is 600rpm, the stirring time is 2h, and the first mixture.

S2. Add 0.3 parts of nucleating agent nanocarbon powder to the first mixed solution, stir and mix. Stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform fluid. The stirring temperature is 35°C, the stirring rate is 600 rpm, and the stirring time 2h, the second mixed solution was obtained.

S3. Add 0.1 part of the crystal modifier soluble starch into the second mixed solution, stir and mix. Stop stirring when the crystal modifier is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 35°C and the stirring rate is 600 rpm. After 2 hours, the third mixed solution was obtained.

S4. Add 1 part of the performance optimizer silver sol into the third mixed solution, stir and mix. Stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 35°C, the stirring rate is 600 rpm, and the stirring time is 2 hours. , to obtain the fourth mixed solution.

S5. Add 1 part of the thickener sodium carboxymethyl cellulose to the fourth mixed solution, stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes a uniform fluid. The stirring temperature is 35°C and the stirring rate is uniform. The stirring time is 800rpm and the stirring time is 4h, and the phase change material is obtained.

Example 4

A low-temperature phase change material with a phase change temperature of 2~8°C, including the following mass parts: 50 parts of phase change coolant (including 30 parts of potassium carbonate and 20 parts of sodium sulfate), nucleating agent nano zinc oxide 3 parts (control particle size is about 180 μm), 0.5 part thickening agent β-cyclodextrin (control particle size is about 70 μm), 0.5 part crystal modifier fumed silica (control particle size is about 80 μm), 3 parts of performance optimizer copper sol (the outer surface is covered with a positive ion layer, the positive ions are H ⁺ , and the particle size is controlled to about 30nm), and 43 parts of water.

Its preparation method includes the following steps:

S1. Take 30 parts of phase change cold storage agent potassium carbonate and 20 parts of sodium sulfate in proportion, slowly add 43 parts of water to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring rate is 400rpm, the stirring time is 1h, and the first mixed solution is obtained .

S2. Add 3 parts of the nucleating agent nano-zinc oxide into the first mixed solution, stir and mix. Stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C, the stirring rate is 400 rpm, and the stirring time for 1 h to obtain the second mixed solution.

S3. Add 0.5 part of the crystal modifier fumed silica to the second mixed solution, stir and mix, stop stirring when the crystal modifier is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C and the stirring rate is 400 rpm. , the stirring time is 1h, and the third mixed solution is obtained.

S4. Add 3 parts of the performance optimizer copper sol into the third mixed solution, stir and mix. Stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 35°C, the stirring rate is 550 rpm, and the stirring time is 1.2 h, the fourth mixed solution is obtained.

S5. Add 0.5 parts of thickener β-cyclodextrin to the fourth mixed solution, stir and mix evenly, stop stirring when the thickener is completely dissolved and the solution is in a uniform fluid state, the stirring temperature is 25° C., the stirring rate is 600 rpm, and the stirring time is 2 h to obtain a phase change material.

Example 5

A low-temperature phase change material with a phase change temperature of 2~8°C, including the following mass parts: 35 parts of phase change coolant (including 20 parts of sodium bicarbonate and 15 parts of sodium chloride), nucleating agent nano 2 parts of copper powder (to control the particle size of about 120 μm), 7 parts of thickener gelatin and 1 part of sodium carboxymethyl starch (to control the particle size of about 70 μm), 0.7 parts of crystal modifier viscose fiber (to control the particle size of about 70 μm) 80 μm), 3 parts of performance optimizer aluminum sol (the outer surface is coated with a positive ion layer, the positive ions are Na ⁺ , and the particle size is controlled to be about 25 nm), and 51.3 parts of water.

Its preparation method includes the following steps:

S1. Take 20 parts of phase change cold storage agent sodium bicarbonate and 15 parts of sodium chloride in proportion, slowly add 51.3 parts of water to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring rate is 400rpm, the stirring time is 1h, and the first mixture.

S2. Add 2 parts of nucleating agent nano-copper powder to the first mixed solution, stir and mix. Stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C, the stirring speed is 400 rpm, and the stirring time for 1 h to obtain the second mixed solution.

S3. Add 0.7 parts of crystal modifier viscose fiber to the second mixed solution, stir and mix, and stop stirring when the crystal modifier is completely dissolved and the solution is in a uniform fluid state. The stirring temperature is 25° C., the stirring rate is 400 rpm, and the stirring time is 1 hour to obtain a third mixed solution.

S4. Add 3 parts of the performance optimizer aluminum sol into the third mixed solution, stir and mix. Stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 35°C, the stirring rate is 550rpm, and the stirring time is 1.2 h, the fourth mixed solution is obtained.

S5. Add 7 parts of thickener gelatin and 1 part of sodium carboxymethyl starch to the fourth mixed solution, stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C. The stirring rate was 600 rpm and the stirring time was 2 h, and the phase change material was obtained.

Example 6

A low-temperature phase change material with a phase change temperature of 2~8°C, including the following mass parts: 40 parts of phase change coolant (including 25 parts of sodium hydroxide, 10 parts of calcium hydroxide, and 5 parts of sodium acetate) , 0.8 parts of nucleating agent carboxylated multi-walled carbon nanotubes (control particle size is about 120 μm), 2 parts of thickening agent activated clay and 6 parts of agar (control particle size is about 70 μm), 0.7 parts of crystal modifier spandex ( The controlled particle size is about 80 μm), 2 parts of performance optimizer copper sol (the outer surface is covered with a positive ion layer, the positive ions are H ⁺ , and the controlled particle size is about 15 nm), and 48.5 parts of water.

The preparation method comprises the following steps:

S1. Take 25 parts of phase change cold storage agent sodium hydroxide, 10 parts of calcium hydroxide and 5 parts of sodium acetate in proportion, slowly add 48.5 parts of water to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring rate is 400rpm, the stirring time 1h, the first mixed solution was obtained.

S2. Add 0.8 parts of the nucleating agent carboxylated multi-walled carbon nanotubes to the first mixed solution, stir and mix. Stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C and the stirring rate is 400rpm, stirring time is 1h, and the second mixed solution is obtained.

S3. Add 0.7 parts of the crystal modifier spandex into the second mixed solution, stir and mix. Stop stirring when the crystal modifier is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C, the stirring rate is 400 rpm, and the stirring time for 1 h to obtain the third mixed solution.

S4. Add 2 parts of the performance optimizer copper sol to the third mixed solution, stir and mix, and stop stirring when the performance optimizer is completely dissolved and the solution is in a uniform fluid state. The stirring temperature is 35° C., the stirring rate is 550 rpm, and the stirring time is 1.2 h to obtain a fourth mixed solution.

S5. Add 2 parts of thickener activated clay and 6 parts of agar to the fourth mixed solution. Stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C and the stirring rate is uniform. The stirring time is 600rpm and the stirring time is 2h, and the phase change material is obtained.

Comparative Example 1

A low-temperature phase change material with a phase change temperature of 2 to 8°C, including the following mass parts: 70 parts of phase change coolant (including 60 parts of sodium carbonate decahydrate and 10 parts of potassium chloride), nucleating agent 3 parts of nano zinc oxide (control particle size is about 100 μm), 1 part thickening agent sodium carboxymethyl cellulose (control particle size is about 70 μm), 0.1 part crystal modifier diatomite (control particle size is about 20 μm) ), 2 parts of performance optimizer gold sol (the outer surface is covered with a positive ion layer, the positive ions are H ⁺ , and the particle size is controlled to be about 1 nm), and 23.9 parts of water.

Its preparation method includes the following steps:

S1. Take 60 parts of phase change cold storage agent sodium carbonate decahydrate and 10 parts of potassium chloride in proportion, slowly add 23.9 parts of water to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring speed is 400rpm, and the stirring time is 1h to obtain the first A mixed solution.

S4. Add 2 parts of the performance optimizer gold sol into the third mixed solution, stir and mix. Stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C, the stirring rate is 400 rpm, and the stirring time is 1h, the fourth mixed solution was obtained.

S5. Add 1 part of the thickener sodium carboxymethyl cellulose to the fourth mixed solution, stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes a uniform fluid. The stirring temperature is 25°C and the stirring rate is uniform. The stirring time is 600rpm and the stirring time is 2h, and the phase change material is obtained.

Comparative example 2

A low-temperature phase change material with a phase change temperature of 2~8°C, including the following mass parts: 45 parts of phase change coolant (including 35 parts of sodium hydroxide and 10 parts of sodium carbonate), nucleating agent nano-oxidation 1 part of zinc, 0.5 part of carbon nanotubes (control particle size is about 120 μm), 1 part of thickening agent xanthan gum (control particle size is about 70 μm), 0.1 part of crystal modifier diatomaceous earth, and 53.4 parts of water.

Its preparation method includes the following steps:

S1. Take 35 parts of phase change cold storage agent sodium hydroxide and 10 parts of sodium carbonate in proportion, slowly add 53.4 parts of water to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring rate is 400rpm, the stirring time is 1h, and the first mixture is obtained solution.

S2. Add 1 part of the nucleating agent nano-zinc oxide and 0.5 part of the carbon nanotube to the first mixed solution, stir and mix, stop stirring when the nucleating agent is completely dissolved and the solution becomes a uniform fluid, the stirring temperature is 25°C, stir The speed is 400 rpm, the stirring time is 1 hour, and the second mixed solution is obtained.

S4. Add 1 part of the thickener xanthan gum to the third mixed solution, stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C and the stirring rate is 600 rpm. The stirring time was all 2h, and the phase change material was obtained.

Comparative Example 3

A low-temperature phase change material with a phase change temperature of 2 to 8°C, including the following mass parts: 45 parts of phase change cold storage agent (including 35 parts of sodium hydroxide and 10 parts of sodium carbonate), thickener xanthan 4 parts of glue (control particle size is about 50 μm), 0.1 part of crystal modifier diatomite (control particle size is about 50 μm), 5 parts of performance optimizer gold sol (the outer surface is coated with a positive ion layer, positive ions It is H ⁺ and the controlled particle size is about 50nm) and 45.9 parts of water.

Its preparation method includes the following steps:

S1. Take 35 parts of phase change cold storage agent sodium hydroxide and 10 parts of sodium carbonate in proportion, slowly add 45.9 parts of water to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring rate is 400rpm, the stirring time is 1h, and the first mixture is obtained solution.

S2. Add 0.1 part of the crystal form modifier diatomite into the first mixed solution, stir and mix. Stop stirring when the crystal form modifier is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C and the stirring rate is 400 rpm. The stirring time is 1 hour, and the second mixed solution is obtained.

S3. Add 5 parts of the performance optimizer gold sol into the second mixed solution, stir and mix. Stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C, the stirring rate is 400 rpm, and the stirring time is 1h, the third mixed solution was obtained.

S4. Add 4 parts of the thickener xanthan gum to the third mixed solution, stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C and the stirring rate is 600 rpm. The stirring time was all 2h, and the phase change material was obtained.

Comparative Example 4

A low-temperature phase change material with a phase change temperature of 2~8°C, including the following mass parts: 45 parts of phase change coolant (including 35 parts of sodium hydroxide and 10 parts of sodium carbonate), nucleating agent nano-oxidation 1 part of zinc and 0.5 part of carbon nanotubes (control particle size is about 150 μm), 0.1 part of crystal modifier diatomite (control particle size is about 80 μm), 5 parts of performance optimizer gold sol (control particle size is about 1 nm) ), 48.4 parts of water.

The preparation method comprises the following steps:

S1. Take 35 parts of phase change cold storage agent sodium hydroxide and 10 parts of sodium carbonate in proportion, slowly add 48.4 parts of sodium carbonate to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring rate is 400rpm, the stirring time is 1h, and the first mixture is obtained solution.

S2. Add 1 part of nucleating agent nano zinc oxide and 0.5 parts of carbon nanotubes to the first mixed solution, stir and mix, and stop stirring when the nucleating agent is completely dissolved and the solution is in a uniform fluid state. The stirring temperature is 25° C., the stirring rate is 400 rpm, and the stirring time is 1 hour to obtain a second mixed solution.

S4. Add 5 parts of the performance optimizer gold sol into the third mixed solution, stir and mix. Stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C, the stirring rate is 400 rpm, and the stirring time is 1h, the phase change material is obtained.

Comparative example 5

A low-temperature phase change material with a phase change temperature of 2~8°C, including the following mass parts: 45 parts of phase change coolant (including 35 parts of sodium hydroxide and 10 parts of sodium carbonate), nucleating agent nano-oxidation 1 part of zinc and 0.5 part of carbon nanotubes (control particle size is about 150 μm), 4 parts of thickening agent xanthan gum (control particle size is about 50 μm), 5 parts of performance optimizer gold sol (the outer surface is coated with positive In the ion layer, the positive ion is H ⁺ and the controlled particle size is about 40 nm) and 44.5 parts of water.

Its preparation method includes the following steps:

S1. Take 35 parts of phase change cold storage agent sodium hydroxide and 10 parts of sodium carbonate in proportion, slowly add 44.5 parts of water to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring rate is 400rpm, the stirring time is 1h, and the first mixture is obtained solution.

Comparative Example 6

A low-temperature phase change material with a phase change temperature of 2~8°C, including the following mass parts: 45 parts of phase change coolant (45 parts of sodium hydroxide), 1 part of nucleating agent nano zinc oxide and carbon nanoparticles 0.5 parts of tube (control particle size is about 150 μm), 4 parts of thickening agent xanthan gum (control particle size is about 50 μm), 0.1 part of crystal form modifier diatomite (control particle size is about 50 μm), performance optimizer 5 parts of gold sol (the outer surface is coated with a positive ion layer, the positive ions are H ⁺ , and the particle size is controlled to be about 60 nm), and 44.4 parts of water.

Its preparation method includes the following steps:

S1. Take 45 parts of the phase change cold storage agent sodium hydroxide in proportion, slowly add 44.4 parts of water to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring speed is 400rpm, the stirring time is 1 hour, and the first mixed solution is obtained.

S2. Add 1 part of the nucleating agent nano-zinc oxide and 0.5 part of the carbon nanotube to the first mixed solution, stir and mix. Stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C. The speed is 400 rpm, the stirring time is 1 hour, and the second mixed solution is obtained.

S5. Add 4 parts of the thickener xanthan gum to the fourth mixed solution, stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C and the stirring rate is 600 rpm. The stirring time was all 2h, and the phase change material was obtained.

Comparative Example 7

A low-temperature phase change material with a phase change temperature of 2 to 8°C, including the following mass parts: 20 parts of phase change coolant (20 parts of sodium carbonate), 1 part of nucleating agent nano zinc oxide and carbon nanotubes 0.5 parts (control particle size is about 150 μm), 4 parts thickener xanthan gum (control particle size is about 50 μm), 0.1 part diatomite improver (control particle size is about 50 μm), performance optimizer gold 5 parts of sol (the outer surface is coated with a positive ion layer, the positive ions are H ⁺ , and the particle size is controlled to be about 70 nm), and 69.4 parts of water.

Its preparation method includes the following steps:

S1. Take 20 parts of phase change cold storage agent sodium carbonate in proportion, slowly add 69.4 parts of water to dissolve, stir and mix evenly, the stirring temperature is 25°C, the stirring speed is 400rpm, the stirring time is 1 hour, and the first mixed solution is obtained.

Comparative example 8

A low-temperature phase change material with a phase change temperature of 2 to 8°C, including the following mass parts: 98 parts of phase change coolant n-tetradecane, 1 part nucleating agent talc, and thickener sodium polyacrylate 1 serving.

Its preparation method includes the following steps:

S1. Add 98 parts of n-tetradecane, a phase change cool storage agent, under stirring. The stirring temperature is 25°C, the stirring rate is 400 rpm, and the stirring time is 1 hour to obtain the first mixed solution.

S2. Add 1 part of nucleating agent talcum powder to the first mixed solution, stir and mix. Stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform and fluid. The stirring temperature is 25°C, the stirring speed is 400 rpm, and the stirring time is 1h, the second mixed solution was obtained.

S3. Add 1 part of thickener sodium polyacrylate to the second mixed solution, stir and mix evenly, stop stirring when the thickener is completely dissolved and the solution is in a uniform fluid state, the stirring temperature is 25° C., the stirring rate is 600 rpm, and the stirring time is 2 h to obtain a phase change material.

Comparative example 9

A low-temperature phase change material with a phase change temperature of 2~8°C, including the following mass parts: 45 parts of phase change coolant (35 parts of sodium hydroxide, 10 parts of sodium carbonate), 1.5 parts of nucleating agent ( 1 part of nano-zinc oxide, 0.5 part of carbon nanotube, control particle size about 10 μm), 4 parts of thickening agent xanthan gum (control particle size of about 20 μm), 0.1 part of crystal modifier diatomite (control particle size About 20 μm), 5 parts of performance optimizer gold sol (the outer surface is not coated with a positive ion layer, and the particle size is controlled to be about 1 nm), and 44.4 parts of water.

Its preparation method includes the following steps:

Performance tests were performed on Examples 1-6 and Comparative Examples 1-9. The test results are shown in the table below:

Table 1. Performance test results of phase change materials of Examples 1-6 and Comparative Examples 1-9

As can be seen from the above table, in the embodiment of the present invention, an inorganic salt composite phase change cold storage agent and water are used as a phase change matrix, and combined with a crystal form modifier, a nucleating agent and a thickening agent to prepare a method for storing and releasing cold water. The amount of phase change material can make the phase change temperature of the prepared phase change material be between 2 and 8°C, the latent heat of phase change >260 kJ/kg, and the thermal conductivity >1.1 W/(m·K), density>1.6 g/cm3, volume expansion rate <0.5%, supercooling <1°C and good cycle stability.

Compared with Examples 1-6, the phase change temperature, phase change latent heat, thermal conductivity density, volume expansion rate, and supercooling degree of the phase change materials of Comparative Examples 1-9 are all worse than those of the phase change materials of the present invention; Comparative Example The phase change temperature of the phase change material in 1 does not reach 2~8°C, and the latent heat of phase change is low; Comparative Example 2 does not add a performance optimizer, resulting in a latent heat of phase change less than 260 kJ/kg, a volume expansion rate greater than 0.5%, and excessive The cooling degree is greater than 1°C and the cycle stability performance is average; Comparative Example 3 does not add a nucleating agent, resulting in the supercooling degree before and after the cycle being greater than 10°C. The supercooling degree is too large, affecting the practical application of the material, causing over-temperature phenomena, and The time to cool down to the target temperature range of 2~8°C is extended, and the thermal conductivity is reduced (because there is no nucleating agent with high thermal conductivity); no thickener is added in Comparative Example 4, resulting in phase stratification, especially when left standing for a long time. Or after the cycle, the phase stratification phenomenon is serious, which further affects the increase in supercooling of the phase change material, uneven temperatures during heat preservation, and the phase change temperature of some materials is not in the heat preservation range; Comparative Example 5 does not add a crystal modifier, resulting in The phase change temperature is reduced, the latent heat of phase change is reduced, and the performance will be further reduced after cycling; Comparative Examples 6 and 7 use a single phase change coolant, and the phase change temperature is too small (1.8°C) or too large (26.4 ℃), the latent heat of phase change decreases and the cycle stability decreases; Comparative Example 8 uses organic phase change cold storage materials. The prepared phase change material has low density, low latent heat of phase change, small thermal conductivity, and large solid-liquid volume expansion rate. A large volume expansion rate causes ice rows (or other fixed containers) to be filled with less phase change materials under the same volume, reducing the holding time; the higher the volume expansion rate, the easier it is to cause ice rows (or other containers) to be filled with less phase change materials. Problems such as bulging, expansion, or even rupture may occur, and problems such as leakage may easily occur; the outermost layer of the performance optimizer in Comparative Example 9 is not coated with positive ions, and the performance optimizer that is not coated with positive ions cannot interact with phase change cold storage. The network structure formed by the agent and crystal modifier forms a larger three-dimensional layered structure, which affects the stability, latent heat of phase change and supercooling of the phase change material.

The above are only examples of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the content of the description of the present invention, or directly or indirectly applied in other related technical fields, shall be regarded as Likewise, it is included in the patent protection scope of the present invention.

Claims

A phase change material with a phase change temperature of 2 to 8°C, characterized by including the following components in parts by mass: 30 to 50 parts of phase change coolant, 0.3 to 3 parts of nucleating agent, and 0.5 to 3 parts of thickener. 8 parts, crystal form improver 0.1~1 part, performance optimizer 1~5 parts, water 35~70 parts;

The phase change cold storage agent includes potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, barium hydroxide, calcium hydroxide, ammonia water, potassium bicarbonate, sodium bicarbonate, potassium chloride, sodium chloride, barium chloride , at least two of potassium nitrate, sodium acetate, sodium sulfate, and disodium hydrogen phosphate;

The crystal form modifier is at least one of diatomite, activated clay, soluble starch, fumed silica, viscose fiber, acetate fiber, polyester, acrylic fiber, spandex, polyvinyl chloride, glass fiber, and asbestos;

The performance optimizer has a spherical structure, and the outer surface of the performance optimizer is covered with a positive ion layer.
The phase change material according to claim 1, characterized in that the particle size of the crystal form modifier is 20 to 100 μm.
The phase change material according to claim 1, characterized in that the nucleating agent is nano carbon powder, graphite powder, nano zinc oxide, nano aluminum oxide, nano copper, nano silicon nitride, carbon nanotubes, carboxylated At least one type of multi-walled carbon nanotubes.
The phase change material according to claim 3, wherein the nucleating agent has a particle size of 10 to 200 μm.
The phase change material according to claim 1, characterized in that the thickener is at least one of polyacrylamide, sodium polyacrylate, sodium carboxymethyl cellulose, sodium hydroxymethyl cellulose, xanthan gum, guar gum, activated clay, gelatin, attapulgite, gum arabic, pectin, agar, tamarind gum, β-cyclodextrin, sodium carboxymethyl starch, and hydroxypropyl starch.
The phase change material according to claim 5, characterized in that the particle size of the thickener is 20~100μm.
The phase change material according to claim 1, characterized in that the performance optimization agent is at least one of gold sol, silver sol, copper sol and aluminum sol.
The phase change material according to claim 7, characterized in that the particle size of the performance optimizer is 1 to 100 nm.
The phase change material according to claim 1, characterized in that the positive ion layer is an H + layer.
A method for preparing a phase change material with a phase change temperature of 2 to 8°C according to any one of claims 1 to 9, characterized in that it includes the following steps:

S1. Take the phase change cold storage agent in proportion, slowly add it to water to dissolve, stir and mix evenly, and obtain the first mixed solution;

S2. Add the nucleating agent to the first mixed solution, stir and mix, stop stirring when the nucleating agent is completely dissolved and the solution becomes uniform and fluid, to obtain the second mixed solution;

S3. Add the crystal form modifier to the second mixed solution, stir and mix, stop stirring when the crystal form modifier is completely dissolved and the solution becomes uniform and fluid, to obtain the third mixed solution;

S4. Add the performance optimizer to the third mixed solution, stir and mix, stop stirring when the performance optimizer is completely dissolved and the solution becomes uniform and fluid, to obtain the fourth mixed solution;

S5. Add the thickener to the fourth mixed solution, stir and mix evenly. Stop stirring when the thickener is completely dissolved and the solution becomes uniform and fluid, to obtain a phase change material.
The method for preparing phase change materials according to claim 10, characterized in that in step S1, the stirring temperature is 25~35°C, the stirring rate is 400~600rpm, and the stirring time is 1~2h.
The method for preparing phase change materials according to claim 10, characterized in that in step S2, the stirring temperature is 25~35°C, the stirring rate is 400~600rpm, and the stirring time is 1~2h.
The method for preparing phase change materials according to claim 10, characterized in that in step S3, the stirring temperature is 20~35°C, the stirring rate is 400~600rpm, and the stirring time is 1~2h.
The method for preparing phase change materials according to claim 10, characterized in that, in step S4, the stirring temperature is 25~35°C, the stirring rate is 400~600rpm, and the stirring time is 1~2h.
The method for preparing phase change materials according to claim 10, characterized in that, in step S5, the stirring temperature is 20~35°C, the stirring rate is 600~800rpm, and the stirring time is 2~4h.