A composite phase change material based on macroscopic encapsulation of a high thermal conductivity and high latent heat wall material and its preparation method

Abstract

The present invention discloses a composite phase-change material based on macroscopic encapsulation of high-thermal-conductivity, high-latent-heat wall materials. The composite phase-change material is obtained by macroscopically encapsulating a ceramic / metal composite phase-change core material with a ceramic / microcapsule composite wall material and then co-sintering the material. The composite phase-change core material is composed of a high proportion of metal particles and ceramic material, a sintering aid, and a polyvinyl alcohol solution, while the composite wall material is composed of metal phase-change microcapsules with thermal expansion cavities, ceramic material, a sintering aid, and a polyvinyl alcohol solution. Through macroscopic encapsulation, the composite phase-change material of the present invention not only balances economic efficiency and low leakage during the phase change process, but also exhibits synergistically enhanced high thermal conductivity and heat storage capacity, as well as excellent cyclic stability. This provides a highly efficient heat storage medium for heat storage systems, meeting their long-term use requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of composite phase change materials, and in particular to a composite phase change material based on macroscopic packaging of high thermal conductivity and high latent heat wall materials and a preparation method thereof. Background Art

[0002] Phase change materials (PCMs), which absorb and release latent heat during solid-liquid phase transitions, have been widely used in various fields, ranging from solar energy utilization, industrial waste heat recovery, thermoelectric energy harvesting, to building temperature control. Encapsulating PCMs is an effective method to protect them from harmful environmental reactions and prevent their leakage. Encapsulation can increase the contact area and improve heat transfer efficiency. Phase change capsules are categorized as nanocapsules (less than 1 μm), microcapsules (1–1000 μm), and macrocapsules (greater than 1 mm). Over the past few decades, nano- / microencapsulated PCMs have attracted considerable attention due to their unique high area-to-volume ratio. However, the volume ratio of the encapsulating shell or support structure can reach 50%, which reduces their latent heat storage density due to the lack of latent heat value in the wall material. Furthermore, the volume changes during solid-liquid phase transition cycles can induce severe stress on the nano / microcapsule shell. Consequently, ensuring the absence of phase change leakage in microcapsule-based energy storage systems is difficult. In contrast, macrocapsules, with their larger PCM core-to-shell volume ratio compared to microcapsules, have also attracted significant interest in recent years.

[0003] When metal phase change materials are used directly, liquid phase leakage, high-temperature oxidation, and high-temperature corrosion can occur during the phase change process. Appropriate encapsulation of phase change materials is an effective solution to this problem. There are many methods for encapsulating phase change materials, with macroencapsulation being particularly effective. Compared to nanocapsules and microcapsules, macroencapsulation offers a larger core-shell volume ratio and higher thermal storage density. However, currently, metal macroencapsulation methods are relatively rare due to the difficulty of macroencapsulating metal phase change materials and the poor cycling durability and stability of the prepared samples. Currently, electroplating and direct coating are used for macroencapsulation of phase change materials. Electroplating utilizes the principle of electrolysis to coat a thin layer of another metal on the surface of a metal sphere, completing the core-shell packaging. However, since the metal shell is easily corroded by most high-temperature liquid metals, it is susceptible to oxidation. Furthermore, metal phase change materials experience significant volume expansion at high temperatures, and the volume increases further after the metal melts, making the directly coated metal sphere packaging susceptible to cracking. Another commonly used packaging material, ceramic wall materials, while relatively stable, have poor thermal conductivity and lack latent heat. Consequently, using them as packaging materials can deplete the latent heat of the phase change material, reducing its thermal performance. These issues are pressing challenges in macro-encapsulation of phase change materials. Summary of the Invention

[0004] In view of the shortcomings of the above-mentioned technology, the present invention provides a composite phase change material based on macroscopic encapsulation of high thermal conductivity and high latent heat wall materials and a preparation method thereof, which solves the problems of leakage during the phase change process of existing metal composite phase change materials, poor cycle stability, high cost of adding microcapsules in high proportions, and macroscopic encapsulation technology, and provides a solution. Specifically, the inventor innovatively proposed a composite phase change material based on macroscopic encapsulation of high thermal conductivity and high latent heat wall materials. The composite phase change material consists of two parts: a ceramic / metal composite phase change core material and a ceramic / microcapsule composite wall material. It has the characteristics of a high addition content of metal particle phase change material, which makes it have excellent heat storage capacity. The present invention adds a small amount of ceramic material to the metal particles to stabilize the shape to make a ceramic / metal composite phase change core material, which effectively alleviates the leakage of the metal phase change material during the phase change process. The ceramic / microcapsule composite wall material of the present invention is composed of ceramic material and metal phase change microcapsules, and the metal phase change microcapsules are prepared by the "double-layer coating, sacrificial inner layer" method; the present invention proposes for the first time to add metal phase change microcapsules to the composite wall material, so that the composite phase change material of the present invention has a high latent heat value and high thermal conductivity, which not only solves the problem that metal particle phase change materials are prone to leakage during the phase change process, but also synergistically enhances the thermal conductivity and heat storage capacity of the composite phase change material, providing a high-efficiency heat storage medium for the heat storage system.

[0005] In order to achieve the above objects, the technical solution adopted by the present invention is:

[0006] A composite phase change material based on macroscopic encapsulation of high thermal conductivity and high latent heat wall materials, the composite phase change material being obtained by macroscopically encapsulating a ceramic / metal composite phase change core material with a ceramic / microcapsule composite wall material and then co-sintering the resultant; the composite phase change core material raw material is composed of a polyvinyl alcohol solution and a ceramic / metal core material mixture, the mass proportion of the ceramic / metal core material mixture in the composite phase change core material raw material is 5-10%, and the ceramic / metal core material mixture is composed of metal particles, 10-30% ceramic material, and 10-20% sintering aids in a mass ratio respectively of 50-80%; the composite wall material raw material is composed of a polyvinyl alcohol solution and a ceramic / microcapsule wall material mixture, the mass proportion of the ceramic / microcapsule wall material mixture in the composite wall material raw material is 5-10%, and the ceramic / microcapsule wall material mixture is composed of metal phase change microcapsules with thermal expansion cavities, 20-70% ceramic material, and 10-20% sintering aids in a mass ratio respectively of 30-70%.

[0007] Furthermore, the metal particles are at least one of tin, bismuth, nickel, iron, cobalt, aluminum, and metal alloy materials containing tin, bismuth, nickel, iron, cobalt, aluminum, and silicon, and have a particle size of 5 to 100 μm.

[0008] Furthermore, the ceramic material is at least one of aluminum oxide, magnesium oxide, diatomaceous earth, silicon carbide, and quartz sand, and has a particle size of 10 to 60 μm.

[0009] Furthermore, the macro-encapsulation operation method is: wrapping the ceramic / microcapsule composite wall material around the ceramic / metal composite phase change core prefabricated sample in a mold, and then pressing the prefabricated sample through the mold at a pressure of 5 to 20 MPa.

[0010] Furthermore, the ceramic / metal composite phase change core preform is obtained by pressing the composite phase change core material through a mold at a pressure of 5 to 15 MPa.

[0011] Furthermore, the sintering aid is medium-high temperature glass powder, and its softening temperature is 300-800°C.

[0012] Furthermore, the polyvinyl alcohol solution is obtained by compounding polyvinyl alcohol powder and water in a mass ratio of 1:10 to 30.

[0013] Furthermore, the phase change temperature difference between the metal particles in the composite phase change core material and the metal phase change microcapsules in the composite wall material is 0-50°C.

[0014] Furthermore, the metal phase change microcapsules use metal particles as core material, the core material is coated with inorganic wall material, a thermal expansion cavity exists between the core material and the inorganic wall material, and the thermal expansion cavity is obtained by heat treatment or reagent dissolution.

[0015] Another aspect of the present invention is to provide a method for preparing the composite phase change material based on macroscopic packaging of high thermal conductivity and high latent heat wall materials as described above, the preparation method comprising the following steps:

[0016] S1: Weigh the following raw materials according to mass ratio: 50-80% metal particles, 10-30% ceramic material and 10-20% sintering aid, and mechanically stir them to obtain a ceramic / metal core material mixture;

[0017] S2: weighing raw materials in a mass ratio of polyvinyl alcohol powder to water of 1:10-30, heating and mixing, and stirring uniformly to obtain a polyvinyl alcohol solution; weighing the polyvinyl alcohol solution and the ceramic / metal core material mixture obtained in step S1 according to the ratio, and mixing and stirring uniformly to obtain a composite phase change core material; placing the composite phase change core material in a mold and die-casting it using a tablet press at a pressure of 5-15 MPa; and then drying it in a drying oven at 60-80°C for 2-4 hours to obtain a ceramic / metal composite phase change core prefabricated sample;

[0018] S3: Weigh the following raw materials according to mass ratio: 30-70% metal phase change microcapsules, 20-70% ceramic materials and 10-20% sintering aids, stir them mechanically until evenly mixed, and then place them in a drying oven at 60-80°C for 2-4 hours to obtain a ceramic / microcapsule wall material mixture; the metal particles in the metal phase change microcapsules in the present invention are consistent with the metal particles in the ceramic / metal composite phase change core prefabricated sample, thereby achieving a synergistic enhancement of the cyclic stability, thermal conductivity and heat storage capacity of the composite phase change material.

[0019] S4: weighing raw materials according to a mass ratio of polyvinyl alcohol powder to water of 1:10-30, heating and mixing, and stirring uniformly to obtain a polyvinyl alcohol solution, weighing the polyvinyl alcohol solution and the ceramic / microcapsule wall material mixture obtained in step S3 according to the ratio, mixing and stirring uniformly to obtain a composite wall material mixture; then spreading half of the composite wall material mixture on the bottom of the mold, placing the ceramic / metal composite phase change core prefabricated sample obtained in S2 in the middle of the composite wall material mixture, and then filling the remaining other half of the composite wall material mixture to cover the ceramic / metal composite phase change core prefabricated sample, and using a tablet press to die-cast at a pressure of 5-20 MPa to obtain a composite phase change material prefabricated sample with a ceramic / microcapsule composite wall material wrapped around the ceramic / metal composite phase change core prefabricated sample;

[0020] S5: sintering the composite phase change material prefabricated sample obtained in step S4 in a calcining furnace at 300-800° C. to obtain a composite phase change material macro-encapsulated based on a high thermal conductivity and high latent heat wall material.

[0021] Beneficial effects of the present invention:

[0022] The composite phase change material prepared by the present invention is based on macro-encapsulation of high thermal conductivity and high latent heat wall materials. The ceramic / metal composite phase change core material is composed of a high proportion of metal particles mixed with a small amount of ceramic material that provides stable shape. It has an excellent latent heat storage capacity of more than 190 J / g; through the macro-encapsulation of ceramic / microcapsule composite wall materials, not only the excellent heat storage capacity of the metal particle phase change material is retained, but also the leakage of the high proportion of metal particles during the phase change process is avoided. The composite wall material also has a high latent heat storage capacity of more than 100 J / g.

[0023] The composite phase change material prepared by the present invention is macro-encapsulated based on a high thermal conductivity and high latent heat wall material. The composite wall material contains metal phase change microcapsules with the same composition as the metal particles of the composite phase change core material, which not only improves the cyclic stability of the composite phase change material, but also further enhances its latent heat storage capacity and thermal conductivity, and has a high thermal conductivity of more than 10 W / (m·k).

[0024] In general, the composite phase change material of the present invention, through macroscopic packaging, not only takes into account the economic benefits and the characteristics of low leakage during the phase change process, but also has synergistically enhanced high thermal conductivity and heat storage capacity and excellent cycle stability, providing a high-efficiency heat storage medium for the heat storage system to meet its long-term use requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron microscope (SEM) photograph of the composite phase change material ceramic / microcapsule composite wall material based on macroscopic encapsulation of high thermal conductivity and high latent heat wall material in Example 1 of the present invention.

[0026] Figure 2 This is a sample cross-sectional morphology photograph of the composite phase change material macro-encapsulated based on high thermal conductivity and high latent heat wall materials according to Example 1 of the present invention.

[0027] Figure 3 This is a sample morphology photograph of the composite phase change material macro-encapsulated based on high thermal conductivity and high latent heat wall materials according to Example 1 of the present invention.

[0028] Figure 4 This is a differential scanning calorimeter (DSC) photograph of the ceramic / metal composite phase change core material of the composite phase change material based on macroscopic encapsulation of high thermal conductivity and high latent heat wall materials in Example 1 of the present invention.

[0029] Figure 5 This is a differential scanning calorimeter (DSC) photograph of the ceramic / microcapsule composite wall material of the composite phase change material macro-encapsulated based on high thermal conductivity and high latent heat wall material in Example 1 of the present invention.

[0030] Figure 6 Schematic diagram comparing the thermal conductivities of the composite phase change material macro-encapsulated by high thermal conductivity and high latent heat wall materials according to Example 1 of the present invention and the composite phase change material macro-encapsulated by ceramic materials according to Comparative Example 1. DETAILED DESCRIPTION

[0031] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0032] Example 1

[0033] The preparation method of the composite phase change material based on macroscopic packaging of high thermal conductivity and high latent heat wall materials of this embodiment includes the following steps:

[0034] S1: Weigh the following raw materials by mass: 72% metal particles (specifically, Al-25% Si metal alloy, with a silicon content of 25% in the aluminum-silicon alloy and a phase transition temperature of 582°C), 18% ceramic material alumina, and 10% sintering aid medium- and high-temperature glass powder (softening temperature of 700°C). The total mass of the sample is 5.5 g. After mechanical stirring for 60 minutes, a ceramic / metal core material mixture is prepared.

[0035] S2: Weigh 5 g of polyvinyl alcohol powder according to proportion, place it in 50 mL of deionized water, mix it, and stir it in a 70°C water bath for 90 minutes to obtain a polyvinyl alcohol solution; weigh the polyvinyl alcohol solution and the ceramic / metal core material mixture prepared in step S1 in a mass ratio of 100:10, mix and stir them evenly for 60 minutes to obtain a composite phase change core material, place the composite phase change core material in a mold, and use a tablet press to die-cast it at a pressure of 15 MPa for 15 minutes to obtain a ceramic / metal composite phase change core prefabricated sample;

[0036] S3: Weigh the following raw materials according to mass ratio: 66% metal phase change microcapsules (phase change temperature: 574°C), 22% ceramic material alumina, and 12% sintering aid medium-high temperature glass powder. The total mass of the sample is 4.5 g. After mechanical stirring for 60 minutes, a ceramic / microcapsule wall material mixture is prepared.

[0037] S4: Weigh 5 g of polyvinyl alcohol powder in proportion, place it in 50 mL of deionized water, mix it, and stir it in a 70°C water bath for 90 minutes to obtain a polyvinyl alcohol solution; weigh the polyvinyl alcohol solution and the ceramic / microcapsule wall material mixture obtained in step S3 in a mass ratio of 100:10, mix and stir evenly for 60 minutes to obtain a composite wall material mixture; then spread half of the composite wall material mixture on the bottom of the mold, place the ceramic / metal composite phase change core prefabricated sample obtained in S2 in the middle of the composite wall material mixture, and then fill the remaining half of the composite wall material mixture to cover the ceramic / metal composite phase change core prefabricated sample, and use a tablet press to die-cast at a pressure of 15 MPa for 15 minutes to obtain a composite phase change material prefabricated sample of a ceramic / microcapsule composite wall material wrapped around a ceramic / metal composite phase change core prefabricated sample;

[0038] S5: After the composite phase change material prefabricated sample obtained in step S4 is sintered in a 700°C roasting furnace, the following Figures 1 to 3 The composite phase change material shown is based on macroscopic encapsulation of high thermal conductivity and high latent heat wall materials.

[0039] The preparation method of the metal phase change microcapsules comprises the following steps:

[0040] S11: Weigh 3 g of spherical metal alloy particles (Al-25% Si, the melting point of the alloy particles is 582° C.) as a core material and uniformly disperse them in 60 mL of deionized water to obtain a dispersion; then, add 2 g of methacrylic acid (MAA) organic monomer to the dispersion, and then add 0.003 g of ammonium persulfate as an initiator. After the addition is completed, an interfacial polymerization reaction is carried out under the assistance of an ultrasonic wave with a power of 200 W. After the reaction is completed for 30 minutes, a pre-microcapsule is obtained. The pre-microcapsule is washed three times with deionized water, filtered, and dried at 90° C. for 4 hours to obtain a metal phase change microcapsule precursor coated with an organic layer, which is abbreviated as PMMA / Al-25% Si phase change microcapsule precursor;

[0041] S12: 100 mL of ethanol and 10 mL of ammonia water were stirred to form a mixed solution, and then 0.8 g of tetraethyl orthosilicate was added while stirring. The mixture was stirred at room temperature for a certain period of time to form a sol. 3 g of the PMMA / Al-25% Si phase change microcapsule precursor obtained in step S11 was weighed and added to the sol. The reaction was stopped after ultrasonic stirring at 70° C. for 1 hour. A gel was formed on the surface of the sol. The sol was washed with ethanol several times, filtered and dried to obtain SiO2 / PMMA / Al-25% Si phase change microcapsules.

[0042] S13: The SiO2 / PMMA / Al-25% Si phase change microcapsules obtained in step S12 are placed in a box-type atmosphere furnace in a N2 atmosphere and heat treated at 400°C for 1 hour, so that the PMMA in the organic layer decomposes into gas and escapes from the interior of the phase change microcapsules to form a thermal expansion cavity layer; the phase change microcapsules with thermal expansion cavities and 3-aminopropyltrimethoxysilane are placed in an ethanol solution at 80°C and a pH of 4.5 and coated again, and 3-aminopropyltrimethoxysilane is hydrolyzed to form a silica coating on the capsule surface to seal the pores on the capsule surface, and finally a metal phase change microcapsule with a thermal expansion cavity is formed.

[0043] The test results show that if Figures 4 to 6 As shown, differential scanning calorimetry tests on composite phase-change materials based on macro-encapsulation of high-thermal-conductivity, high-latent-heat wall materials revealed that the ceramic / metal composite phase-change core material obtained by macro-encapsulation in this embodiment had a latent heat value of 280.2 J / g and a peak melting temperature of 588.89°C; the ceramic / microcapsule composite wall material had a latent heat value of 208.9 J / g and a peak melting temperature of 580.93°C. The thermal conductivity of the composite phase-change material obtained by macro-encapsulation in this embodiment was 17.75 W / (m·K).

[0044] Comparative Example 1

[0045] The preparation method of the composite phase change material of this comparative example is basically the same as that of Example 1, except that, in the preparation method of the composite phase change material of this comparative example, no metal phase change microcapsules are added to the ceramic / microcapsule wall material mixture in step S3.

[0046] The test results show that if Figure 6 As shown, the thermal conductivity of the composite phase change material obtained by macroscopic packaging in this comparative example is 2.38 W / (m·K).

[0047] Example 2

[0048] The preparation method of the composite phase change material of this embodiment is basically the same as that of Example 1, except that, in the preparation method of the composite phase change material of this embodiment, step S1 is: the ceramic / metal core material mixture is weighed according to the mass ratio of the following raw materials: 80% metal particles (specifically Al-25% Si metal alloy, whose phase change temperature is 582°C), 10% ceramic material alumina and 10% sintering aid medium and high temperature glass powder, and the total mass of the sample is 5.5g.

[0049] Test results using differential scanning calorimetry (DSC) show that the ceramic / metal composite phase-change core material obtained by macro-encapsulation using high-thermal-conductivity, high-latent-heat wall materials in this embodiment has a latent heat of 300.6 J / g and a peak melting temperature of 587.97°C. The ceramic / microcapsule composite wall material has a latent heat of 208.5 J / g and a peak melting temperature of 580.32°C. The thermal conductivity of the composite phase-change material obtained by macro-encapsulation in this embodiment is 17.91 W / (m·K).

[0050] Example 3

[0051] The preparation method of the composite phase change material of this embodiment is basically the same as that of Example 1, except that, in the preparation method of the composite phase change material of this embodiment, step S1 is: the ceramic / metal core material mixture is weighed according to the mass ratio of the following raw materials: 60% metal particles (specifically Al-25% Si metal alloy, whose phase change temperature is 582°C), 20% ceramic material alumina and 20% sintering aid medium and high temperature glass powder, and the total mass of the sample is 5.5g.

[0052] Test results using differential scanning calorimetry (DSC) show that the ceramic / metal composite phase-change core material obtained by macro-encapsulation using high-thermal-conductivity, high-latent-heat wall materials exhibited a latent heat of 224.2 J / g and a peak melting temperature of 585.63°C. The ceramic / microcapsule composite wall material exhibited a latent heat of 207.4 J / g and a peak melting temperature of 579.25°C. The thermal conductivity of the macro-encapsulated composite phase-change material obtained by this embodiment was 13.56 W / (m·K).

[0053] Example 4

[0054] The preparation method of the composite phase change material of this embodiment is basically the same as that of Example 1, except that, in the preparation method of the composite phase change material of this embodiment, in step S1: the ceramic / metal core material mixture is weighed according to the mass ratio of the following raw materials: 50% metal particles (specifically Al-25% Si metal alloy, whose phase change temperature is 582°C), 30% ceramic material alumina and 20% sintering aid medium and high temperature glass powder, and the total mass of the sample is 5.5g.

[0055] Test results using differential scanning calorimetry (DSC) show that the ceramic / metal composite phase-change core material obtained by macro-encapsulation using high-thermal-conductivity, high-latent-heat wall materials in this embodiment has a latent heat of 190.5 J / g and a peak melting temperature of 583.19°C. The ceramic / microcapsule composite wall material has a latent heat of 208.7 J / g and a peak melting temperature of 580.31°C. The thermal conductivity of the composite phase-change material obtained by macro-encapsulation in this embodiment is 10.34 W / (m·K).

[0056] Example 5

[0057] The preparation method of the composite phase change material of this embodiment is basically the same as that of Example 1, except that, in the preparation method of the composite phase change material of this embodiment, in step S3: the ceramic / microcapsule wall material mixture is weighed according to the mass ratio of the following raw materials: 70% metal phase change microcapsules (phase change temperature: 574°C), 18% ceramic material alumina and 12% sintering aid medium and high temperature glass powder, and the total mass of the sample is 4.5g.

[0058] Test results using differential scanning calorimetry (DSC) show that the ceramic / metal composite phase-change core material obtained by macro-encapsulation using high-thermal-conductivity, high-latent-heat wall materials in this embodiment exhibited a latent heat of 280.6 J / g and a peak melting temperature of 587.91°C. The ceramic / microcapsule composite wall material exhibited a latent heat of 218.57 J / g and a peak melting temperature of 581.85°C. The thermal conductivity of the macro-encapsulated composite phase-change material in this embodiment was 17.89 W / (m·K).

[0059] Example 6

[0060] The preparation method of the composite phase change material of this embodiment is basically the same as that of Example 1, except that, in the preparation method of the composite phase change material of this embodiment, in step S3: the ceramic / microcapsule wall material mixture is weighed according to the mass ratio of the following raw materials: 50% metal phase change microcapsules (phase change temperature: 574°C), 30% ceramic material alumina and 20% sintering aid medium and high temperature glass powder, and the total mass of the sample is 4.5g.

[0061] Test results using differential scanning calorimetry (DSC) show that the ceramic / metal composite phase-change core material obtained by macro-encapsulation using high-thermal-conductivity, high-latent-heat wall materials exhibited a latent heat of 280.2 J / g and a peak melting temperature of 588.79°C. The ceramic / microcapsule composite wall material exhibited a latent heat of 168.25 J / g and a peak melting temperature of 582.03°C. The thermal conductivity of the macro-encapsulated composite phase-change material obtained by this embodiment was 13.41 W / (m·K).

[0062] Example 7

[0063] The preparation method of the composite phase change material of this embodiment is basically the same as that of Example 1, except that, in the preparation method of the composite phase change material of this embodiment, in step S3: the ceramic / microcapsule wall material mixture is weighed according to the mass ratio of the following raw materials: 30% metal phase change microcapsules (phase change temperature: 574°C), 58% ceramic material alumina and 12% sintering aid medium and high temperature glass powder, and the total mass of the sample is 4.5g.

[0064] Test results using differential scanning calorimetry (DSC) show that the ceramic / metal composite phase-change core material obtained by macro-encapsulation using high-thermal-conductivity, high-latent-heat wall materials exhibited a latent heat of 281.3 J / g and a peak melting temperature of 588.75°C. The ceramic / microcapsule composite wall material exhibited a latent heat of 105.93 J / g and a peak melting temperature of 582.33°C. The thermal conductivity of the macro-encapsulated composite phase-change material obtained by this embodiment was 10.61 W / (m·K).

[0065] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Various changes and improvements are possible without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the invention as claimed.

Claims

1. A composite phase change material based on macroscopic packaging of high thermal conductivity and high latent heat wall material, characterized in that: The composite phase change material is obtained by macro-encapsulating a ceramic / metal composite phase change core material with a ceramic / microcapsule composite wall material and then co-sintering the material; the composite phase change core material raw material is composed of a polyvinyl alcohol solution and a ceramic / metal core material mixture, the mass proportion of the ceramic / metal core material mixture in the composite phase change core material raw material is 5-10%, and the ceramic / metal core material mixture is composed of a mass ratio of 50-80% metal particles, 10-30% ceramic material and 10-20% sintering aid respectively; the composite wall material raw material is composed of a polyvinyl alcohol solution and a ceramic / microcapsule wall material mixture, the ceramic / microcapsule wall material mixture is 5-10% by mass. The mass proportion of the material in the composite wall material raw material is 5-10%, and the ceramic / microcapsule wall material mixture is composed of 30-70% metal phase change microcapsules with thermal expansion cavities, 20-70% ceramic material and 10-20% sintering aid in a mass ratio respectively; the metal particles are at least one of tin, bismuth, nickel, iron, cobalt, aluminum metal and metal alloy materials including tin, bismuth, nickel, iron, cobalt, aluminum and silicon elements; the ceramic material is at least one of aluminum oxide, magnesium oxide, diatomaceous earth, silicon carbide and quartz sand; the sintering aid is medium-high temperature glass powder with a softening temperature of 300-800°C.

2. The composite phase change material based on macroscopic packaging of high thermal conductivity and high latent heat wall material according to claim 1, characterized in that: The macro packaging operation method is: wrapping the ceramic / microcapsule composite wall material on the ceramic / metal composite phase change core prefabricated sample in a mold, and then pressing the mold at a pressure of 5 to 20 MPa.

3. The composite phase change material based on macroscopic packaging of high thermal conductivity and high latent heat wall material according to claim 2, characterized in that: The ceramic / metal composite phase change core prefabricated sample is obtained by pressing the composite phase change core material through a mold at a pressure of 5 to 15 MPa.

4. The composite phase change material based on macroscopic packaging of high thermal conductivity and high latent heat wall material according to claim 1, characterized in that: The polyvinyl alcohol solution is obtained by compounding polyvinyl alcohol powder and water in a mass ratio of 1:10-30.

5. The composite phase change material based on macroscopic packaging of high thermal conductivity and high latent heat wall material according to claim 1, characterized in that: The phase change temperature difference between the metal particles in the composite phase change core material and the metal phase change microcapsules in the composite wall material is 0-50°C.

6. The composite phase change material based on macroscopic packaging of high thermal conductivity and high latent heat wall material according to claim 1, characterized in that: The metal phase change microcapsules use metal particles as core material, which is covered with inorganic wall material. A thermal expansion cavity exists between the core material and the inorganic wall material, and the thermal expansion cavity is obtained by heat treatment or reagent dissolution.

7. The composite phase change material based on macroscopic packaging of high thermal conductivity and high latent heat wall material according to claim 1, characterized in that: After the composite material prefabricated sample is sintered in a baking furnace at 300-800 DEG C, a composite phase change material based on macroscopic encapsulation of high thermal conductivity and high latent heat wall materials is obtained.

8. A method for preparing a composite phase change material based on macroscopic encapsulation of a high thermal conductivity and high latent heat wall material according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: S1: Weigh the following raw materials according to mass ratio: 50-80% metal particles, 10-30% ceramic material and 10-20% sintering aid, and mechanically stir them to obtain a ceramic / metal core material mixture; S2: weighing raw materials in a mass ratio of polyvinyl alcohol powder to water of 1:10-30, heating and mixing, and stirring uniformly to obtain a polyvinyl alcohol solution; weighing the polyvinyl alcohol solution and the ceramic / metal core material mixture obtained in step S1 according to the ratio, and mixing and stirring uniformly to obtain a composite phase change core material; placing the composite phase change core material in a mold and die-casting it using a tablet press at a pressure of 5-15 MPa; and then drying it in a drying oven at 60-80°C for 2-4 hours to obtain a ceramic / metal composite phase change core prefabricated sample; S3: Weigh the following raw materials according to mass ratio: 30-70% metal phase change microcapsules with thermal expansion cavities, 20-70% ceramic material, and 10-20% sintering aid, stir them mechanically until uniform, and dry them in a drying oven at 60-80°C for 2-4 hours to prepare a ceramic / microcapsule wall material mixture; S4: weighing raw materials according to a mass ratio of polyvinyl alcohol powder to water of 1:10-30, heating and mixing, and stirring uniformly to obtain a polyvinyl alcohol solution, weighing the polyvinyl alcohol solution and the ceramic / microcapsule wall material mixture obtained in step S3 according to the ratio, mixing and stirring uniformly to obtain a composite wall material mixture; then spreading half of the composite wall material mixture on the bottom of the mold, placing the ceramic / metal composite phase change core prefabricated sample obtained in S2 in the middle of the composite wall material mixture, and then filling the remaining other half of the composite wall material mixture to cover the ceramic / metal composite phase change core prefabricated sample, and using a tablet press to die-cast at a pressure of 5-20 MPa to obtain a composite phase change material prefabricated sample with a ceramic / microcapsule composite wall material wrapped around the ceramic / metal composite phase change core prefabricated sample; S5: sintering the composite phase change material prefabricated sample obtained in step S4 in a calcining furnace at 300-800° C. to obtain a composite phase change material macro-encapsulated based on a high thermal conductivity and high latent heat wall material.

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