Solid-solid phase change aggregate for heat storage and preparation method thereof
By using porous shell hollow ceramic balls and polymer packaging methods, the problem of easy leakage of solid-liquid phase change materials is solved, and the stability and easy mass production of solid-solid phase change materials are achieved, which is suitable for building energy conservation.
Patent Information
- Application Number
- CN202510583636.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-07
- Publication Date
- 2025-07-29
AI Technical Summary
Existing phase-change aggregate medium solid-liquid phase change materials are prone to leakage, the packaging process is complex and difficult to mass-produce on a large scale, affecting the performance and heat storage capacity of building materials.
The hollow ceramic balls with a porous shell are used as the carrier of the solid-solid phase change material. The solid-solid phase change material is encapsulated inside the hollow ball by vacuum adsorption method and encapsulated by polymer to ensure the waterproofness and stability of the material.
The stability and waterproofness of solid-solid phase change materials are achieved, and the leakage problem of solid-liquid phase change materials is avoided. The preparation process is simple and easy to mass production on a large scale, suitable for building energy saving.
Smart Images
Figure CN120383443A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of phase change aggregates, and more particularly to a preparation method of a solid-solid phase change material for heat storage. Background Art
[0002] Phase change heat storage materials can absorb heat in a high-temperature environment and release heat in a low-temperature environment. During the heat absorption and heat release processes, their temperatures remain basically unchanged. Using phase change heat storage materials in a building system can effectively reduce indoor temperature fluctuations, achieve energy conservation and consumption reduction, and improve living comfort by utilizing the heat storage and heat release characteristics of the phase change heat storage capacity. Generally speaking, phase change aggregates include phase change materials, matrix materials, and encapsulation materials. Phase change materials can be divided into solid-liquid phase change materials, solid-solid phase change materials, solid-gas phase change materials, and liquid-gas phase change materials according to the phase change process. At present, the most commonly used phase change material in phase change aggregates is the solid-liquid phase change material. As the name implies, the solid-liquid phase change material undergoes a transformation from solid to liquid during the phase change process, and the liquid phase change material is prone to leakage, resulting in damage to the performance of building materials and a decrease in heat storage capacity. To overcome the leakage problem, researchers use porous materials such as expanded perlite, expanded vermiculite, diatomite, etc. as matrix materials to make shaped phase change materials to adsorb phase change materials. However, during the long-term cooling and heating cycles, the phase change material in the shaped phase change material still leaks; researchers further use epoxy resin, etc. for encapsulation, which greatly reduces the energy density of the phase change aggregate, and the encapsulation process is complex, the aggregates adhere to each other, the curing time is long, the encapsulation effect is unstable, it is difficult to achieve large-scale production, and it is difficult to meet the needs of market development. Summary of the Invention
[0003] Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a preparation method of a solid-solid phase change aggregate that does not leak, has a simple preparation process, and can be mass-produced. The solid-solid phase change material has a solid-solid phase change stage and a solid-liquid phase change stage. Generally speaking, the difference between the solid-solid phase change temperature and the solid-liquid phase change temperature is large, and the solid-solid phase change temperature is low. During the solid-solid phase change stage, the state of the phase change material does not change and always remains solid. The present invention precisely utilizes this characteristic of the solid-solid phase change material to prepare a solid-solid phase change aggregate. The solid-solid phase change material has the characteristic of being soluble in water. During the application of the solid-solid phase change aggregate in a building system, it is inevitable to come into contact with water. To ensure the stability of the solid-solid phase change aggregate, the solid-solid phase change material is encapsulated in the present invention. Phase change aggregates often need to have a certain strength. To achieve this purpose, hollow ceramic balls with a porous shell layer are used as the carrier of the solid-solid phase change material in the present invention.
[0004] The technical solution adopted by the present invention to solve the above technical problem is:
[0005] The technical solution of the present invention includes three parts. The first part is to prepare solid-solid phase change materials suitable for building systems; the second part is to prepare matrix materials suitable for building systems, that is, the carrier of solid-solid phase change materials; the third part is the adsorption and encapsulation of solid-solid phase change materials, that is, using a vacuum adsorption method to adsorb the phase change material into the matrix material and encapsulate it.
[0006] Step 1: Solid-solid phase change material: Select or prepare a solid-solid phase change material and put it into a container. Place it in a high temperature environment and wait for the phase change material to be completely melted.
[0007] Step 2, preparing a template: preparing a sodium alginate solution and a metal ion solution, immersing the plastic ball in the sodium alginate solution and then in the metal ion solution, so that a layer of gel is formed on the surface of the plastic ball.
[0008] Step 3: Granulation: Put the plastic balls and powder into a granulator and granulate them into round particles.
[0009] Step 4: Drying: The particles obtained in step 3 are placed in an environment with a certain temperature for drying.
[0010] Step 5, sintering: placing the particles dried in step 4 in a high temperature environment for high temperature sintering to obtain a hollow sphere with a porous shell.
[0011] Step 6, vacuum adsorption: Place the hollow balls into the solid-solid phase change material obtained in step 1, and then place it in a vacuum high-temperature environment for a period of time.
[0012] Step 7: Wipe: Clean the surface of the ball after adsorbing the phase change material obtained in step 6.
[0013] Step 8: Preparation of packaging materials: fully mix the polymer monomer and initiator in a certain mass ratio.
[0014] Step 9, packaging material adsorption: The pellets obtained in step 7 are placed in the packaging material prepared in step 8, and then placed in a vacuum environment for vacuum adsorption for a period of time.
[0015] Step 10, polymerization reaction: After the small balls in step 9 are fished out and wiped clean, they are placed in a high temperature environment for a period of time and wait for the polymerization reaction to be complete, thereby obtaining a leak-proof solid-solid phase change aggregate.
[0016] In the said step 1, the solid-solid phase change material can be a single-component material, or a binary or ternary hybrid material; the solid-solid phase change material is selected from one or more of neopentyl glycol, trimethylolethane, pentaerythritol, polyethylene glycol, and tris(hydroxymethyl)aminomethane; the solid-solid phase change temperature of the solid-solid phase change material is 18~60°C; the temperature in the high-temperature environment should be higher than the solid-liquid phase change temperature of the solid-solid phase change material.
[0017] In the said step 2, the mass fraction of the sodium alginate solution is 0.5~2%; the metal ions in the metal ion solution can be calcium ions, iron ions, zinc ions, barium ions, aluminum ions, etc., and their mass fraction can be 10~50%; the material of the plastic balls can be polymers such as polystyrene and polyethylene, and their particle size can be 5~15 mm.
[0018] In the said step 3, the powder can be one or more of fly ash, silica, alumina, silicon nitride, silicon carbide, mullite, titanium dioxide, iron ore, iron oxide, etc.; there should be enough powder to completely cover the surface of the small balls; a granulator is used in the granulation process, and its rotation speed and tilt angle should be suitable for granulation, the rotation speed can be 15~45 r / min, and the tilt angle is 20~45°.
[0019] In the said step 4, the temperature of the drying environment can be 25~45°C, and the drying time can be 4~12 h until there is no excess moisture on the surface of the powder.
[0020] In the said step 5, the roasting process is divided into two stages: the first stage is low-temperature sintering, rising from room temperature to 250~350°C, with a heating rate of 0.2°C / min~1.5°C / min, and holding for 30~90 min; the second stage is high-temperature roasting, continuing to heat up from the holding temperature of the first stage to 1000~1400°C, with a heating rate of 1°C / min~5°C / min, and holding for 30~90 min; during the cooling process, the cooling rate is kept not greater than 5°C / min.
[0021] In the said step 6, the temperature in the vacuum chamber should be higher than the solid-liquid phase change temperature of the solid-solid phase change material; vacuum adsorption adopts the method of gradually decreasing the vacuum degree. First, adjust the vacuum degree to 80~90 kPa for adsorption. At this time, the temperature in the vacuum chamber will drop. Wait until the temperature in the vacuum chamber returns to the initial temperature, then adjust the vacuum degree to 60~70 kPa for adsorption. At this time, the temperature in the vacuum phase will drop. Wait until the temperature in the vacuum chamber returns to the initial temperature, then adjust the vacuum degree to 40~50 kPa for adsorption, and so on, until the vacuum degree is reduced to 0~10 kPa. Wait for the temperature to return to the initial temperature and then adsorb for 1~2 h; the solid-solid phase change material is neopentyl glycol and its mixture with other alcohol materials.
[0022] In step 8, the polymer monomers can be ethylene, styrene, methyl methacrylate, vinyl chloride, etc., and the initiators can be corresponding initiators such as potassium persulfate and ammonium persulfate. The mass fraction of the initiator in the monomers is 0.1 - 2%.
[0023] In step 9, the vacuum adsorption time can be 1 - 4 h.
[0024] In step 10, the temperature of the high - temperature environment needs to meet the temperature conditions for the polymerization reaction of the polymer monomers and at the same time be lower than the solid - liquid phase transition temperature of the solid - solid phase change material. Generally, it can be maintained at 50 - 100 °C; the reaction time is determined according to the initiator and the reaction temperature, and generally can be 0.5 - 4 h.
[0025] The present invention adopts the above - mentioned technical solution and has the following beneficial effects:
[0026] The aggregate uses hollow ceramic balls with a porous shell layer as the carrier of the solid - solid phase change material. After melting the solid - solid phase change material, it is adsorbed into the interior of the hollow balls, and the exterior of the hollow balls is encapsulated with a polymer to ensure the waterproofness and stability of the material. The phase transition temperature of the solid - solid phase change material in this aggregate is relatively low. During the solid - solid phase transition stage, the state of the phase change material does not change and always remains solid, thus avoiding the problem of easy leakage of the solid - liquid phase change material.
[0027] The present invention uses a solid - solid phase change material to replace the solid - liquid phase change material to prepare a phase - change aggregate, and develops a polymer encapsulation method according to the characteristics of the solid - solid phase change material, making it have good waterproofness and stability. And the overall preparation process has simple technology, is easy to promote, and has low cost. Compared with traditional phase - change aggregates, it is more suitable for use in phase - change concrete for building energy conservation. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 It is a fly - ash hollow ball with a porous shell - layer structure.
[0029] Figure 2 It is the DSC curve of the binary solid - solid phase change material.
[0030] Figure 3 It is the encapsulated solid - solid phase - change aggregate.
[0031] Figure 4 It is the scanning electron microscope image of the encapsulated solid - solid phase - change aggregate.
[0032] Figure 5 It is the DSC curve of neopentyl glycol.
[0033] Figure 6 It is the sectional view of the neopentyl glycol solid - solid phase - change aggregate. DETAILED DESCRIPTION OF THE INVENTION
[0034] The present invention is further explained below with reference to the embodiments and drawings, but they are not intended to limit the scope of protection of the present application.
[0035] The technical solution of this invention includes three parts: the first is the preparation of a solid-solid phase change material suitable for building systems; the second is the preparation of a matrix material suitable for building systems, i.e., the carrier of the solid-solid phase change material; and the third is the adsorption and encapsulation of the solid-solid phase change material, i.e., the use of vacuum adsorption to adsorb the phase change material into the matrix material and encapsulate it. Step 1, Solid-Solid Phase Change Material: Select or prepare a solid-solid phase change material, place it in a container, and place it in a high-temperature environment. Wait until the phase change material is completely melted and set aside.
[0036] Step 2, preparing a template: preparing a sodium alginate solution and a metal ion solution, immersing the plastic ball in the sodium alginate solution and then in the metal ion solution, so that a layer of gel is formed on the surface of the plastic ball.
[0037] Step 3: Granulation: Put the plastic balls and powder into a granulator and granulate them into round particles.
[0038] Step 4: Drying: The particles obtained in step 3 are placed in an environment with a certain temperature for drying.
[0039] Step 5, sintering: placing the particles dried in step 4 in a high temperature environment for high temperature sintering to obtain a hollow sphere with a porous shell.
[0040] Step 6: Vacuum adsorption: Place the hollow balls into the phase change material obtained in step 1, and then place it in a vacuum high-temperature environment for a period of time.
[0041] Step 7: Wipe: Clean the surface of the ball after adsorbing the phase change material obtained in step 6.
[0042] Step 8: Preparation of packaging materials: fully mix the polymer monomer and initiator in a certain mass ratio.
[0043] Step 9, packaging material adsorption: The pellets obtained in step 7 are placed in the packaging material prepared in step 8, and then placed in a vacuum environment for vacuum adsorption for a period of time.
[0044] Step 10, polymerization reaction: After the small balls in step 9 are fished out and wiped clean, they are placed in a high temperature environment for a period of time and wait for the polymerization reaction to be complete, thereby obtaining a leak-proof solid-solid phase change aggregate.
[0045] In the said Step 1, the solid-solid phase change material can be a single-component material, or a binary or ternary hybrid material; the solid-solid phase change temperature of the solid-solid phase change material is 18~32°C; the temperature in the high-temperature environment should be higher than the solid-liquid phase change temperature of the solid-solid phase change material.
[0046] In the said Step 2, the mass fraction of the sodium alginate solution is 0.5~2%; the metal ions in the metal ion solution can be calcium ions, iron ions, zinc ions, barium ions, aluminum ions, etc., and its mass fraction can be 10~50%; the material of the plastic balls can be polymers such as polystyrene and polyethylene, and its particle size can be 5~15mm.
[0047] In the said Step 3, the powder material can be one or a mixture of fly ash, silica, alumina, silicon nitride, silicon carbide, mullite, titanium dioxide, iron ore, iron oxide, etc.; there should be enough powder material to completely coat the surface of the small balls; a granulator is used during the granulation process, and its rotation speed and tilt angle should be suitable for granulation, the rotation speed can be 15~45r / min, and the tilt angle is 20~45°.
[0048] In the said Step 4, the temperature of the drying environment can be 25~45°C, and the drying time can be 4~12h until there is no excess moisture on the surface of the powder material.
[0049] In the said Step 5, the roasting process is divided into two stages: the first stage is low-temperature sintering, rising from room temperature to 250~350°C, with a heating rate of 0.2°C / min~1.5°C / min, and holding for 30~90min; the second stage is high-temperature roasting, continuing to heat up from the holding temperature of the first stage to 1000~1400°C, with a heating rate of 1°C / min~5°C / min, and holding for 30~90min; during the cooling process, the cooling rate is kept not greater than 5°C / min.
[0050] In the said Step 6, the temperature in the vacuum chamber should be higher than the solid-liquid phase change temperature of the solid-solid phase change material; vacuum adsorption adopts the method of gradually reducing the vacuum degree. First, adjust the vacuum degree to 80~90kPa for adsorption. At this time, the temperature in the vacuum chamber will drop. Wait until the temperature in the vacuum chamber returns to the initial temperature, then adjust the vacuum degree to 60~70kPa for adsorption. At this time, the temperature in the vacuum chamber will drop again. Wait until the temperature in the vacuum chamber returns to the initial temperature, then adjust the vacuum degree to 40~50kPa for adsorption, and so on in a cycle until the vacuum degree is reduced to 0~10kPa. After waiting for the temperature to return to the initial temperature, adsorb for another 1~2h.
[0051] In step 8, polymer monomers can be ethylene, styrene, methyl methacrylate, vinyl chloride, etc., and initiators can be corresponding initiators such as potassium persulfate and ammonium persulfate. The mass fraction of the initiator in the monomer is 0.1 - 2%.
[0052] In step 9, the vacuum adsorption time can be 1 - 4 h.
[0053] In step 10, the temperature of the high - temperature environment needs to meet the temperature conditions for the polymerization reaction of polymer monomers and at the same time be lower than the solid - liquid phase transition temperature of the solid - solid phase change material. Generally, it can be maintained at 50 - 100 °C; the reaction time is determined according to the initiator and reaction temperature, and generally can be 0.5 - 4 h.
[0054] Example 1
[0055] A solid - solid phase change aggregate prepared with a mixture of trimethylolethane and neopentyl glycol as the binary solid - solid phase change material, fly ash hollow spheres as the matrix material, and polymethyl methacrylate as the encapsulation material.
[0056] First, pour calcium chloride powder and water into a beaker according to the mass ratio, place a magnetic rotor and then put it into a water bath with magnetic stirring function. Set the rotation speed to 800 r / min and stir for 10 - 20 min until evenly stirred to obtain a 20% calcium chloride solution by mass fraction; take another beaker, pour sodium alginate powder and water into the beaker according to the mass ratio, place a magnetic rotor and then put it into a water bath with magnetic stirring function. Set the water bath temperature to 60 °C, the rotation speed to 500 r / min, and stir for 1 - 2 h until evenly stirred to form a 2% sodium alginate solution. Then immerse the foam balls in the sodium alginate solution first to make a layer of sodium alginate solution adhere to their surfaces and then take them out, and then immerse them in the calcium chloride solution so that a layer of calcium alginate wraps the foam balls and put them into a beaker for standby. After obtaining a batch of foam balls wrapped with calcium alginate, take out the dried fly ash from an oven set at 80 °C, wait for it to cool to room temperature, place the foam balls and the dried fly ash in batches in a disk granulator, use water as the binder for granulation, take them out after the diameter of the fly ash balls is about 1.5 cm, and place them in a crucible for standby. After obtaining a batch of fly ash balls, place them in an oven, set the oven temperature to 40 °C, the air volume to the minimum, and dry for more than 4 h. Place the dried fly ash balls in a muffle furnace, set the sintering temperature to 1200 °C, and calcine to obtain fly ash hollow spheres. Figure 1 The fly ash hollow spheres after sintering have a porous shell - layer structure, with a diameter of about 1.2 cm, plump and complete particles, no obvious voids on the surface, and showing yellow throughout. After the calcination is completed, take a beaker and prepare a mixture of neopentyl glycol and trimethylolethane with a mass ratio of 89:11. Figure 2It is the DSC curve of the binary solid-solid phase change material. It can be seen that the solid-solid phase change temperature occurs at about 27°C. Put the mixture and the completely pore-free fly ash hollow spheres after calcination into a beaker, where the mixture covers the fly ash spheres by 1 - 1.5 cm, and place it in an oil bath. Set the temperature to 180°C and the heating time to 45 - 60 min until the mixture melts. After melting, stir it evenly. Place the liquid mixture and the fly ash spheres in a vacuum drying oven. Set the temperature to 160°C and the pressure to 60 kPa first. Reduce the pressure by 10 kPa every 20 min until it reaches 20 kPa and then adsorb for 1 h until no bubbles are observed. Take out the fly ash spheres adsorbed with neopentyl glycol and trimethylolethane and cool them to room temperature. Take a beaker, put the fly ash spheres into it, pour in methyl methacrylate enough to cover the fly ash spheres, and then add azobisisobutyronitrile with a mass fraction of 0.8% as an initiator. After stirring evenly, put it into a vacuum drying oven. Set the temperature to 15°C and the pressure to 60 kPa first. Reduce the pressure by 20 kPa every 10 min until it reaches 20 kPa and then adsorb for 20 min until no bubbles are observed. Place the fly ash spheres with methyl methacrylate adsorbed on the surface in a beaker and place it in a water bath. Set the temperature to 80°C and heat for 1.5 - 2.5 h until the methyl methacrylate is completely polymerized into polymethyl methacrylate to obtain the encapsulated fly ash-based solid-solid phase change aggregate. Figure 3 It is the encapsulated solid-solid phase change aggregate. Figure 4 It is the scanning electron microscope image of the encapsulated solid-solid phase change aggregate. It can be seen that a dense network structure adheres to the surface of the shell layer and water molecules cannot pass through.
[0057] Example 2:
[0058] A solid-solid phase change material prepared with neopentyl glycol as the solid-solid phase change material, fly ash hollow spheres as the matrix material, and polymethyl methacrylate as the encapsulation material.
[0059] First, pour calcium chloride powder and water into a beaker according to the mass ratio. After placing a magnetic rotor, put it in a water bath with magnetic stirring function, set the rotation speed to 800 r / min, and stir for 10 - 20 min until evenly stirred to obtain a calcium chloride solution with a mass fraction of 20%. Take another beaker, pour sodium alginate powder and water into the beaker according to the mass ratio. After placing a magnetic rotor, put it in a water bath with magnetic stirring function, set the water bath temperature to 60 °C, set the rotation speed to 500 r / min, and stir for 1 - 2 h until evenly stirred to form a sodium alginate solution with a mass fraction of 2%. Subsequently, immerse the foam balls in the sodium alginate solution first to make a layer of sodium alginate solution adhere to their surfaces and then take them out. Then immerse them in the calcium chloride solution so that a layer of calcium alginate wraps the surface of the foam balls and put them in a beaker for standby. After preparing a batch of foam balls wrapped with calcium alginate, take out the dried fly ash from an oven set at 80 °C. Wait for it to cool to room temperature. Place the foam balls and the dried fly ash in batches in a disk granulator, and use water as a binder for granulation. Take them out after the diameter of the fly ash balls is about 1.5 cm and place them in a crucible for standby. After preparing a batch of fly ash balls, place them in an oven, set the oven temperature to 40 °C, set the air volume to the minimum, and dry for more than 4 h. Place the dried fly ash balls in a muffle furnace, set the sintering temperature to 1200 °C, and calcine to obtain fly ash hollow balls. Figure 1 The fly ash hollow balls have a porous shell structure after sintering, with a diameter of about 1.2 cm, full and complete particles, no obvious voids on the surface, and a yellow color throughout. After the calcination is completed, take a beaker, put the fly ash hollow balls into the beaker, and then put in neopentyl glycol. Figure 5 This is the DSC curve of neopentyl glycol. It can be seen that the solid-solid phase change temperature occurs at about 40 °C. Among them, the neopentyl glycol submerges the fly ash balls by 1 - 1.5 cm, and place it in an oil bath, set the temperature to 180 °C, and the heating time to 45 - 60 min until the mixture melts. After melting, stir evenly. Place the liquid neopentyl glycol and fly ash balls in a vacuum drying oven, set the temperature to 160 °C, set the pressure to 60 kPa first, reduce it by 10 kPa every 20 min until 20 kPa, and then adsorb for 1 h until no bubbles are observed. Take out the fly ash balls adsorbed with neopentyl glycol and cool them to room temperature. Take a beaker, put the fly ash balls into it, pour in methyl methacrylate enough to submerge the fly ash balls, and then add azobisisobutyronitrile with a mass fraction of 0.8% as an initiator. After stirring evenly, put it in a vacuum drying oven, set the temperature to 15 °C, the pressure to 60 kPa first, reduce it by 20 kPa every 10 min until 20 kPa, and then adsorb for 20 min until no bubbles are observed. Place the fly ash balls with methyl methacrylate adsorbed on the surface in a beaker and put it in a water bath, set the temperature to 80 °C, and heat for 1.5 - 2.5 h until the methyl methacrylate is completely polymerized into polymethyl methacrylate to obtain the encapsulated fly ash-based solid-solid phase change aggregate.Figure 6 Cross-sectional view of the neopentyl glycol solid-solid phase change aggregate.
[0060] The above embodiments are only used to illustrate the present invention, and any equivalent transformation and improvement made on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.
Claims
1. A preparation method of a solid-solid phase change aggregate for heat storage, characterized in that, The preparation method includes the following steps: Step 1: Heat the solid-solid phase change material until the phase change material is completely melted, and then set it aside for later use; Step 2: Prepare the template: Prepare a sodium alginate solution and a metal ion solution. Immerse the plastic balls in the sodium alginate solution and then in the metal ion solution to form a gel layer on the surface of the plastic balls, obtaining gel plastic balls; Step 3: Granulation: Put the gel plastic balls and the powder into a granulator, obtain round particles through granulation, and dry them; Step 4: Sintering: Perform high-temperature roasting on the dried particles to obtain hollow balls with a porous shell layer; Step 5: Vacuum adsorption: Put the hollow balls into the solid-solid phase change material melted in Step 1, and perform vacuum adsorption to obtain adsorbed phase change material balls; Step 6: Encapsulating material adsorption: Put the adsorbed phase change material balls into the encapsulating material, and then perform vacuum adsorption to obtain adsorbed encapsulating material balls; The encapsulating material includes polymer monomers and initiators; Step 7: Polymerization reaction: Heat the adsorbed encapsulating material balls until the polymerization reaction of the encapsulating material is complete to obtain solid-solid phase change aggregates.
2. The preparation method according to claim 1, characterized in that: The solid-solid phase change temperature of the solid-solid phase change material is 18~60°C; The solid-solid phase change material is selected from one or more of neopentyl glycol, trimethylolethane, pentaerythritol, polyethylene glycol, and tris(hydroxymethyl)aminomethane.
3. The preparation method according to claim 1, characterized in that: In Step 2, the mass fraction of the sodium alginate solution is 0.5~2%; The metal ions in the metal ion solution are calcium ions, iron ions, zinc ions, barium ions, or aluminum ions, and their mass fraction can be 10~50%; The material of the plastic balls is polystyrene or polyethylene polymer, and their particle size is 5~15 mm.
4. The preparation method according to claim 1, characterized in that: In Step 3, the powder is selected from one or more of fly ash, silica, alumina, silicon nitride, silicon carbide, mullite, titanium dioxide, iron ore, and iron oxide.
5. The preparation method according to claim 1, characterized in that: In Step 4, the roasting process is divided into two stages: The first stage is low-temperature sintering, rising from room temperature to 250~350°C, with a heating rate of 0.2°C / min~1.5°C / min, and holding for 30~90 min; The second stage is high-temperature roasting, continuing to heat from the holding temperature of the first stage to 1000~1400°C, with a heating rate of 1°C / min~5°C / min, and holding for 30~90 min; During the cooling process, the cooling rate is kept not greater than 5°C / min.
6. The preparation method according to claim 1, characterized in that: In Step 5, the temperature in the vacuum chamber should be higher than the solid-liquid phase change temperature of the solid-solid phase change material; Vacuum adsorption adopts the method of gradually decreasing the vacuum degree. First, adjust the vacuum degree to 80~90 kPa for adsorption; When the temperature in the vacuum chamber returns to the initial temperature, then decrease the vacuum degree by 10 kPa for adsorption, wait for the temperature in the vacuum chamber to return to the initial temperature, and so on in a cycle until the vacuum degree is reduced to 0~10 kPa, and then adsorb for 1~2 h after waiting for the temperature to return to the initial temperature.
7. The preparation method according to claim 1, characterized in that: In Step 6, the polymer monomers are one or more of ethylene, styrene, methyl methacrylate, and vinyl chloride, and the initiators are potassium persulfate, ammonium persulfate, and azobisisobutyronitrile. The mass fraction of the initiator in the monomer is 0.1~2%; The vacuum adsorption time is 1~4 h.
8. The preparation method according to claim 1, wherein: In step 7, the heating temperature needs to be higher than the temperature condition for the polymerization reaction of the polymer monomer to occur, and at the same time lower than the solid-liquid phase transition temperature of the solid-solid phase change material.
9. The preparation method according to claim 1, characterized in that: The heating temperature is 50~100°C; the reaction time is 0.5~4 h.
10. A solid-solid phase change aggregate for heat storage, characterized in that, The phase change aggregate is prepared by the preparation method described in any one of claims 1-9; The phase change aggregate sequentially includes a solid-solid phase change material, a matrix material layer, and a packaging material layer from the inside to the outside.