Preparation method of temperature-adjustable long-term heat storage composite phase change hydrogel

Abstract

The invention relates to a preparation method of temperature-adjustable long-term heat storage composite phase change hydrogel. The method comprises the following steps: 1) dispersing a hydrogel basic unit guar gum powder by using a dispersing agent; 2) adding water, a phase change agent, a temperature regulator, an interface agent and a nano heat conduction enhancing additive, and uniformly stirring; and 3) adding a cross-linking agent solution, continuously stirring until gel is formed, heating at 65 DEG C for 2-3 hours, stirring for 2-3 times during the period, taking out, naturally cooling to room temperature, and centrifugally defoaming. The temperature can be adjusted, various application scenes can be met, and cross-season long-term storage of heat can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of polymers, and in particular to a method for preparing a temperature-adjustable long-term heat storage composite phase-change hydrogel. Background Art

[0002] In production and life, the use of phase change thermal storage materials can greatly reduce energy costs, but different usage scenarios have different performance requirements for phase change thermal storage materials. For example, in the field of facility agriculture, different climatic conditions, different greenhouse structures, different crops, and different application methods also have different phase change temperatures for phase change materials.

[0003] On the other hand, there is abundant heat in summer, while winter is a season that requires a lot of heating, so it is also crucial to achieve long-term storage of heat from summer to winter. Summary of the Invention

[0004] In order to solve the technical problems existing in the background technology, the present invention provides a method for preparing a temperature-adjustable long-term heat storage phase change hydrogel, which not only has adjustable temperature to meet various application scenarios, but also can realize long-term storage of heat across seasons.

[0005] The technical solution of the present invention is: the present invention is a method for preparing a temperature-adjustable long-term heat storage composite phase change hydrogel, the special feature of which is that the preparation method comprises the following steps:

[0006] 1) dispersing guar gum powder, a basic unit of hydrogel, using a dispersant;

[0007] 2) Add water, phase change agent, temperature regulator, interface agent, and nano thermal conductivity enhancing additive and stir evenly;

[0008] 3) Add the crosslinker solution and continue stirring until a gel is formed. Then heat at 65°C for 2-3 hours, stirring 2-3 times during the heating. Remove the mixture and cool it naturally to room temperature. Centrifuge to degas.

[0009] Furthermore, the guar gum powder as the basic unit of the hydrogel is guar gum, cationic guar gum, hydroxypropyl guar gum or other guar gum derivatives.

[0010] Furthermore, the dispersant is ethanol, ethylene glycol or glycerol.

[0011] Furthermore, the phase change agent is sodium acetate.

[0012] Furthermore, the temperature regulator is formamide, urea or acetamide.

[0013] Furthermore, the interface agent and the temperature regulator are the same substance.

[0014] Furthermore, the nano thermal conductivity enhancing additive is one or more of graphite, graphene, carbon nanotubes, carbon powder, carbon fiber, metal powder, aluminum oxide powder, and aluminum nitride powder.

[0015] Furthermore, the cross-linking agent solution is a sodium tetraborate solution.

[0016] Furthermore, the preparation method comprises the following steps:

[0017] 1) As needed, mix sodium tetraborate and hot water above 80°C in a ratio of 1:3 to 1:5 and stir thoroughly to prepare solution A;

[0018] 2) Mix 2-4 parts of guar gum and 15-25 parts of dispersant, stir well, and prepare solution B;

[0019] 3) Add 70-80 parts of room temperature deionized water to solution B and stir continuously until the powder is completely dissolved to prepare solution C;

[0020] 4) adding 100-150 parts of a phase change agent, 10-75 parts of a temperature regulator and an interface agent, and 4-6 parts of a nano thermal conductivity enhancing additive to solution C and stirring uniformly to obtain a mixture D;

[0021] 5) taking 20 to 30 portions of solution A and slowly adding them dropwise into mixture D while stirring, thereby preparing a temperature-adjustable long-term heat storage composite phase change hydrogel;

[0022] 6) In order to make its performance more stable, the prepared temperature-adjustable long-term heat storage composite phase change hydrogel was heated at 65°C for 2 to 3 hours, stirred 2 to 3 times during the period, cooled naturally, and then centrifuged at 2500 rpm for 5 min for degassing.

[0023] A method for releasing heat from the temperature-adjustable long-term heat storage composite phase change hydrogel at low temperatures, the method comprising the following steps:

[0024] 1) Sodium acetate is formed into a shaped block or rod-shaped structure using an adhesive. When heat release is required, the shaped block or rod-shaped object is brought into contact with a temperature-adjustable long-term heat storage composite phase change hydrogel via a motor to promote nucleation and heat release. After heat release is triggered, the shaped block or rod-shaped object is retracted;

[0025] 2) Use a 300-400W ultrasonic rod. When heat release is required, power on the ultrasonic rod until heat is released.

[0026] 3) A semiconductor refrigeration chip is embedded in the packaging material of the temperature-adjustable long-term heat storage composite phase change hydrogel. When heat release is required, the semiconductor refrigeration is turned on to reduce the temperature of part of the temperature-adjustable long-term heat storage composite phase change hydrogel to -10℃~-20℃, thereby promoting its non-thermal nucleation.

[0027] The present invention provides a method for preparing a temperature-adjustable, long-term heat-storage phase-change hydrogel. This method not only offers adjustable temperature to meet a variety of application scenarios but also enables long-term heat storage across seasons. The composite phase-change hydrogel prepared in this invention is composed of a polymer hydrogel, a hydrated salt phase-change material, a temperature regulator, an interface agent, and a nano-thermal conductivity-enhancing additive. It exhibits shape stability, adjustable phase-change temperature, and stable, long-term heat storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A flow chart for preparing the materials of the present invention;

[0029] Figure 2 The DSC curves of the temperature regulation effects of the four temperature regulators at different contents in the present invention are shown;

[0030] Figure 3 is the phase change enthalpy of the four temperature regulators in the present invention at different contents. DETAILED DESCRIPTION

[0031] The present invention provides a method for preparing a temperature-adjustable long-term heat storage composite phase change hydrogel, comprising the following steps:

[0032] 1) dispersing guar gum powder, a basic unit of hydrogel, using a dispersant;

[0033] 2) Add water, phase change agent, temperature regulator, interface agent, and nano thermal conductivity enhancing additive and stir evenly;

[0034] 3) Add the crosslinker solution and continue stirring until a gel is formed. Then heat at 65°C for 2-3 hours, stirring 2-3 times during the heating. Remove the mixture and cool it naturally to room temperature. Centrifuge to degas.

[0035] The guar gum powder, the basic unit of the hydrogel, is guar gum, cationic guar gum, hydroxypropyl guar gum, or other guar gum derivatives. The dispersant is ethanol, ethylene glycol, or glycerol. The phase change agent is sodium acetate. The temperature regulator is a strong polar additive such as formamide, urea, or acetamide. The interfacial agent plays a role in maintaining the structural stability of the phase change hydrogel. It is the same substance as the temperature regulator. When temperature regulation is not required, a certain amount of additive must also be added as an interfacial agent to prevent liquid precipitation and phase separation. The nano thermal conductivity enhancing additive is one or more of graphite, graphene, carbon nanotubes, carbon powder, carbon fiber, metal powder, aluminum oxide powder, and aluminum nitride powder. The crosslinking agent solution is a sodium tetraborate solution.

[0036] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0037] join Figure 1 , the method flow of the present invention is as follows:

[0038] 1) As needed, mix sodium tetraborate and hot water above 80°C in a ratio of 1:3 to 1:5 and stir thoroughly to prepare solution A;

[0039] 2) Mix 2-4 parts of guar gum and 15-25 parts of dispersant, stir well, and prepare solution B;

[0040] 3) Add 70-80 parts of room temperature deionized water to solution B and stir continuously until the powder is completely dissolved to prepare solution C;

[0041] 4) adding 100-150 parts of a phase change agent, 10-75 parts of a temperature regulator and an interface agent, and 4-6 parts of a nano thermal conductivity enhancing additive to solution C and stirring uniformly to obtain a mixture D;

[0042] 5) taking 20 to 30 portions of solution A and slowly adding them dropwise into mixture D while stirring, thereby preparing a temperature-adjustable long-term heat storage composite phase change hydrogel;

[0043] 6) In order to make its performance more stable, the prepared temperature-adjustable long-term heat storage composite phase change hydrogel was heated at 65°C for 2 to 3 hours, stirred 2 to 3 times during the period, cooled naturally, and then centrifuged at 2500 rpm for 5 min for degassing.

[0044] The present invention also provides a method for releasing heat at low temperatures from a temperature-adjustable long-term heat storage composite phase change hydrogel, the method comprising the following steps:

[0045] 1) Sodium acetate is formed into a shaped block or rod-shaped structure using an adhesive. When heat release is required, the shaped block or rod-shaped object is brought into contact with a temperature-adjustable long-term heat storage composite phase change hydrogel via a motor to promote nucleation and heat release. After heat release is triggered, the shaped block or rod-shaped object is retracted;

[0046] 2) Use a 300-400W ultrasonic rod. When heat release is required, power on the ultrasonic rod until heat is released.

[0047] 3) A semiconductor refrigeration chip is embedded in the packaging material of the temperature-adjustable long-term heat storage composite phase change hydrogel. When heat release is required, the semiconductor refrigeration is turned on to reduce the temperature of part of the temperature-adjustable long-term heat storage composite phase change hydrogel to -10℃~-20℃, thereby promoting its non-thermal nucleation.

[0048] In a specific embodiment of the present invention, the temperature-adjustable long-term heat storage composite phase change hydrogel is composed of hydroxypropyl guar gum as the hydrogel basic monomer, glycerol as the dispersant, sodium acetate as the phase change agent, urea and formamide as the temperature regulator and interface agent, sodium tetraborate as the crosslinking agent, and expanded graphite as the thermal conductivity enhancing additive.

[0049] In this specific embodiment, the synthesis method of the adjustable long-term heat storage composite phase change hydrogel is:

[0050] 1) Mix sodium tetraborate and hot water above 80° C. in a mass ratio of 1:3 to 1:4 and stir thoroughly to prepare solution A, which is set aside;

[0051] 2) Mix 2-4 parts of guar gum and 15-25 parts of propylene glycol, stir well, and prepare solution B;

[0052] 3) Add 70-80 parts of room temperature deionized water to solution B and stir continuously until the powder is completely dissolved to prepare solution C;

[0053] 4) adding 100-150 parts of sodium acetate, 10-75 parts of urea or formamide, and 4-6 parts of expanded graphite to solution C and stirring uniformly to obtain a mixture D;

[0054] 5) Take 20 to 30 parts of solution A and slowly add them dropwise into mixture D while stirring to prepare a temperature-adjustable long-term heat storage composite phase change hydrogel;

[0055] 6) In order to make its performance more stable, the prepared temperature-adjustable long-term heat storage composite phase change hydrogel was heated at 65°C for 2 to 3 hours, stirred 2 to 3 times during the period, cooled naturally, and then centrifuged at 2500 rpm for 5 min for degassing.

[0056] See also Figure 2 The DSC curves of the temperature regulation effect of the four temperature regulators of the present invention at different contents are shown. From top to bottom (i to iv) in the figure, the DSC curves of the phase transition temperature are respectively adjusted using formamide, urea, acetamide, and glycerol. It can be seen from the figure that the phase transition temperature is effectively adjusted using formamide, acetamide, and urea.

[0057] See also Figure 3 The phase change enthalpy of the four temperature regulators of the present invention at different contents is shown in the figure from left to right (i to iv) respectively. The phase change enthalpy after the phase change temperature is adjusted using different contents of formamide, urea, acetamide, and propylene glycol. It can be seen from the figure that the phase change enthalpy loss is small and the phase change enthalpy is still large.

[0058] The present invention also provides a method for releasing heat at low temperatures using a temperature-adjustable long-term heat storage composite phase-change hydrogel, the method comprising the following steps:

[0059] 1) Clay, water, and sodium acetate are mixed and placed into a rod-shaped mold, and dried to form a rod.

[0060] 2) When the temperature-adjustable long-term heat storage composite phase change hydrogel is cooled to room temperature, a rod is used to touch the hydrogel to cause it to crystallize and release heat.

[0061] The above are only specific embodiments disclosed in the present invention, but the protection scope disclosed in the present invention is not limited thereto. The protection scope disclosed in the present invention shall be based on the protection scope of the claims.

[0062] The content of the present invention and the technical content not specifically described in the above embodiments are the same as the prior art.

[0063] The present invention is not limited to the above embodiments, and all of the contents of the present invention can be implemented and have the above good effects.

Claims

1. A method for preparing a temperature-adjustable long-term heat storage composite phase change hydrogel, characterized by: The preparation method comprises the following steps: 1) dispersing guar gum powder, a basic unit of hydrogel, using a dispersant; 2) Add water, phase change agent, temperature regulator, interface agent, and nano thermal conductivity enhancing additive and stir evenly; 3) Add the crosslinker solution and continue stirring until a gel is formed. Then heat at 65°C for 2-3 hours, stirring 2-3 times during the heating. Remove the mixture and cool it naturally to room temperature. Centrifuge to degas.

2. The method for preparing the temperature-adjustable long-term heat storage composite phase change hydrogel according to claim 1, characterized in that: The guar gum powder, a basic unit of the hydrogel, is guar gum, cationic guar gum, hydroxypropyl guar gum or other guar gum derivatives.

3. The method for preparing the temperature-adjustable long-term heat storage composite phase change hydrogel according to claim 2, characterized in that: The dispersant is ethanol, ethylene glycol or glycerol.

4. The method for preparing the temperature-adjustable long-term heat storage composite phase change hydrogel according to claim 3, characterized in that: The phase change agent is sodium acetate.

5. The method for preparing the temperature-adjustable long-term heat storage composite phase change hydrogel according to claim 4, characterized in that: The temperature regulator is formamide, urea or acetamide.

6. The method for preparing the temperature-adjustable long-term heat storage composite phase change hydrogel according to claim 5, characterized in that: The interface agent is mixed with formamide, urea or acetamide.

7. The method for preparing the temperature-adjustable long-term heat storage composite phase change hydrogel according to claim 6, characterized in that: The nano thermal conductivity enhancing additive is one or more of graphite, graphene, carbon nanotubes, carbon powder, carbon fiber, metal powder, aluminum oxide powder, and aluminum nitride powder.

8. The method for preparing the temperature-adjustable long-term heat storage composite phase change hydrogel according to claim 7, characterized in that: The cross-linking agent solution is a sodium tetraborate solution.

9. The method for preparing the temperature-adjustable long-term heat storage composite phase change hydrogel according to claim 8, characterized in that: The preparation method comprises the following steps: 1) As needed, mix sodium tetraborate and hot water above 80°C in a ratio of 1:3 to 1:5 and stir thoroughly to prepare solution A; 2) Mix 2-4 parts of guar gum and 15-25 parts of dispersant, stir well, and prepare solution B; 3) Add 70-80 parts of room temperature deionized water to solution B and stir continuously until the powder is completely dissolved to prepare solution C; 4) adding 100-150 parts of a phase change agent, 10-75 parts of a temperature regulator and an interface agent, and 4-6 parts of a nano thermal conductivity enhancing additive to solution C and stirring uniformly to obtain a mixture D; 5) Take 20 to 30 parts of solution A and slowly add them dropwise into mixture D while stirring to prepare a temperature-adjustable long-term heat storage composite phase change hydrogel; 6) In order to make its performance more stable, the prepared temperature-adjustable long-term heat storage composite phase change hydrogel was heated at 65°C for 2 to 3 hours, stirred 2 to 3 times during the period, cooled naturally, and then centrifuged at 2500 rpm for 5 min for degassing.

10. A method for releasing heat at low temperatures from the temperature-adjustable, long-term heat storage composite phase-change hydrogel according to claim 1, characterized in that: The method comprises the following steps: 1) Sodium acetate is formed into a shaped block or rod-shaped structure using an adhesive. When heat release is required, the shaped block or rod-shaped object is brought into contact with a temperature-adjustable long-term heat storage composite phase change hydrogel via a motor to promote nucleation and heat release. After heat release is triggered, the shaped block or rod-shaped object is retracted; 2) Use a 300-400W ultrasonic rod. When heat release is required, power on the ultrasonic rod until heat is released. 3) A semiconductor refrigeration chip is embedded in the packaging material of the temperature-adjustable long-term heat storage composite phase change hydrogel. When heat release is required, the semiconductor refrigeration is turned on to reduce the temperature of part of the temperature-adjustable long-term heat storage composite phase change hydrogel to -10℃~-20℃, thereby promoting its non-thermal nucleation.

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