Composite high-temperature phase change heat storage material and preparation method thereof

Abstract

The invention relates to a composite high-temperature phase change heat storage material and a preparation method thereof. According to the technical scheme, the preparation method comprises the following steps: uniformly mixing aluminum sol, silica sol and aluminum fluoride powder to obtain mixed sol; and immersing the rice husk activated carbon powder in the mixed sol in vacuum, drying, carrying out heat treatment in an air atmosphere at 900-1200 DEG C, grinding, and screening to obtain porous powder particles containing mullite whiskers. And uniformly mixing the porous powder particles containing the mullite whiskers, sodium chloride powder and potassium chloride powder to obtain a mixture I, and carrying out heat treatment, grinding and screening on the mixture I in an air atmosphere at 700-900 DEG C to obtain the modified eutectic salt powder. Uniformly mixing alumina micro powder, tabular corundum powder, modified eutectic salt powder and aluminum dihydrogen phosphate powder to obtain a mixture II; and carrying out compression molding on the mixture II, and carrying out heat treatment in an air atmosphere at 700-800 DEG C to prepare the composite high-temperature phase change heat storage material. The prepared product is good in thermal shock resistance, high in compression strength, good in cycling stability and high in thermal conductivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of phase change heat storage materials. Specifically, it relates to a composite high-temperature phase change heat storage material and a preparation method thereof. Background Art

[0002] With the acceleration of the industrialization and urbanization processes, the energy situation has become increasingly tense, and the contradiction between energy supply and demand has intensified. Traditional heat storage methods have problems such as low efficiency and high costs. Phase change heat storage materials store and release thermal energy through the phase change process of substances, and have advantages such as high heat storage density and small temperature fluctuations. They have become an important means to solve the problems of energy storage and conversion, and have broad application prospects in the fields of solar energy utilization, power load shifting, and waste heat recovery. Those skilled in the art have conducted in-depth research on this:

[0003] The patented technology of "A Preparation Method of an Inorganic Phase Change Heat Storage Material (CN202410471514.9)". Although the inorganic phase change heat storage gel powder prepared by this technology has advantages such as high thermal conductivity and simple preparation process, it has problems of poor cycle stability and low compressive strength.

[0004] The patented technology of "An Al@AlN-C Composite Core-Shell Structure Phase Change Heat Storage Material and Preparation Method (CN202311658955.1)". This technology uses metallic aluminum as the phase change medium and prepares composite phase change heat storage capsules by the microcapsule method. Although the prepared composite heat storage capsules have a large heat transfer area, there is a lack of effective regulation of the thermal shock stability of the material.

[0005] The patented technology of "A Preparation Method of a Molten Salt Porous Silicon-Based Composite Phase Change Heat Storage Material (CN202110256063.3)". This technology uses molten salt with high latent heat as the phase change heat storage material to solve the problem of easy leakage of molten salt during use. Although it improves the heat storage capacity of the composite material, the composite material has problems such as low thermal conductivity and low compressive strength.

[0006] The patented technology of "A High-Temperature Phase Change Heat Storage Composite Material and Preparation Method Thereof (CN20201X443646.9)". This technology coats the surface of ternary aluminum-based alloy powder to obtain a high-temperature composite phase change heat storage material. Although this heat storage material has a large heat storage density and high compressive strength, its cycle stability is poor and its thermal shock stability is low.

[0007] In summary, the existing high-temperature phase change heat storage materials have the following technical defects: poor thermal shock stability, low compressive strength, poor cycle stability, and low thermal conductivity. Summary of the Invention

[0008] The present invention aims to overcome the technical defects existing in the prior art, and the purpose is to provide a preparation method of a composite high-temperature phase change heat storage material. The composite high-temperature phase change heat storage material prepared by this method has excellent thermal shock stability, high compressive strength, good cycle stability and excellent thermal conductivity.

[0009] To achieve the above purpose, the specific steps of the technical solution adopted by the present invention are as follows:

[0010] Step 1: Mix 52-68 wt% of aluminum sol, 30-40 wt% of silica sol and 2-8 wt% of aluminum fluoride powder evenly to obtain a mixed sol. Immerse the rice husk activated carbon powder in the mixed sol under the condition of a vacuum degree of -0.1 to -0.05 MPa for 30-60 min, then dry it at 100-110 °C for 10-12 h, and then heat-treat it in an air atmosphere at 900-1200 °C for 1-3 h, grind and sieve to obtain porous powder particles containing mullite whiskers with a particle size less than 0.088 mm.

[0011] Step 2: Mix 20-40 wt% of the porous powder particles containing mullite whiskers, 20-40 wt% of sodium chloride powder and 20-60 wt% of potassium chloride powder evenly to obtain mixture I. Heat-treat mixture I in an air atmosphere at 700-900 °C for 2-4 h, grind and sieve to obtain modified eutectic salt powder with a particle size less than 0.088 mm.

[0012] Step 3: Mix 30-40 wt% of alumina micropowder, 8-22 wt% of tabular corundum powder, 40-50 wt% of modified eutectic salt powder and 2-8 wt% of aluminum dihydrogen phosphate powder evenly to obtain mixture II; press mixture II into a mold under the condition of 40-60 MPa, and heat-treat it in an air atmosphere at 700-800 °C for 2-4 h to prepare a composite high-temperature phase change heat storage material.

[0013] The average particle size of the colloidal particles of the aluminum sol is 8-25 nm; the chemical components of the aluminum sol are: the content of Al2(SO4)3 is greater than 14.50 wt%; the pH of the aluminum sol is 7-9.

[0014] The average particle size of the colloidal particles of the silica sol is 8-25 nm; the chemical components of the silica sol are: the content of SiO2 is greater than 25.50 wt%; the pH of the silica sol is 8.5-9.5.

[0015] The aluminum fluoride powder is of analytical purity; the content of AlF3 in the aluminum fluoride powder is greater than 99 wt%.

[0016] The particle size of the rice husk activated carbon powder is less than 0.088 mm, and the average pore diameter of the rice husk activated carbon powder is 10 μm; the chemical components of the rice husk activated carbon powder are: the C content is 20-40 wt%, the SiO2 content is 20-40 wt%, and the loss on ignition is 50-60 wt%.

[0017] The particle size of the sodium chloride powder is less than 0.088 mm; the NaCl content of the sodium chloride powder is greater than 99 wt%.

[0018] The particle size of the potassium chloride powder is less than 0.088 mm; the KCl content of the potassium chloride powder is greater than 99 wt%.

[0019] The particle size of the alumina fine powder is 1-2 μm; the Al2O3 content of the alumina fine powder is greater than 99 wt%.

[0020] The particle size of the tabular corundum powder is less than 0.045 mm; the Al2O3 content of the tabular corundum is greater than 99 wt%.

[0021] The particle size of the aluminum dihydrogen phosphate powder is less than 0.088 mm; the Al(H2PO4)3 content of the aluminum dihydrogen phosphate is greater than 99 wt%.

[0022] Due to the adoption of the above technical solutions, the present invention has the following positive effects compared with the prior art:

[0023] (1) The present invention defines the particle gradation of the raw materials. Through the binding effect of aluminum dihydrogen phosphate during the heat treatment process of the composite material, the densification of the composite high-temperature phase change heat storage material is promoted, the mechanical properties of the composite high-temperature phase change heat storage material are improved, and the prepared composite high-temperature phase change heat storage material has high compressive strength; at the same time, by defining the particle gradation, the internal pore size of the composite high-temperature phase change heat storage material is small, and mullite whiskers are in-situ synthesized in the inorganic salt, hindering the migration of molten salt at high temperature, and thus it is difficult for the molten salt to leak during the thermal cycle. The prepared composite high-temperature phase change heat storage material has high compressive strength and good cycle stability.

[0024] (2) The present invention utilizes the loss on ignition of rice husk activated carbon and the catalytic characteristics of aluminum fluoride powder during the heat treatment process, fully retains the pore structure of rice husk activated carbon, and enables mullite whiskers to grow with rice husk activated carbon as a template. And during the subsequent heat treatment process, the mullite whiskers further interweave and grow in the inorganic salt, forming a stable network structure, which can relieve the mechanical stress caused by the expansion and contraction of the inorganic salt. Combining with the good thermal shock resistance of mullite whiskers itself, the prepared composite high-temperature phase change heat storage material has excellent thermal shock stability.

[0025] (3) The present invention makes full use of the characteristic of relatively high thermal conductivity of alumina, creates a relatively high degree of densification through particle packing, and effectively improves the heat transfer capacity of the composite high-temperature phase change heat storage material. At the same time, an intertwined whisker structure is formed in the inorganic salt, effectively reducing the interfacial thermal resistance between inorganic salt particles and improving the heat transfer efficiency. The prepared composite high-temperature phase change heat storage material has excellent thermal conductivity.

[0026] The service temperature range of the composite high-temperature phase change heat storage material prepared by the present invention is 600 - 800 °C. The main properties of the composite high-temperature phase change heat storage material are detected as follows: bulk density ≥ 2.73 g / cm 3 ; thermal conductivity ≥ 2.2 W / (m·K); thermal shock stability ≥ 28 times (800 °C, air cooling); compressive strength ≥ 51.3 MPa; no new phase is generated after 100 thermal cycles, and the mass loss rate ≤ 0.11 wt% (600 - 800 °C); heat storage density ≥ 253.3 kJ / kg (600 - 800 °C).

[0027] Therefore, the composite high-temperature phase change heat storage material prepared by the present invention has excellent thermal shock stability, high compressive strength, good cycle stability and excellent thermal conductivity. Specific Embodiments

[0028] The following further describes the present invention in combination with specific implementation methods, which is not a limitation to its protection scope.

[0029] A composite high-temperature phase change heat storage material and its preparation method. The preparation method described in this specific embodiment is as follows:

[0030] Step 1: Mix 52 - 68 wt% of aluminum sol, 30 - 40 wt% of silica sol and 2 - 8 wt% of aluminum fluoride powder evenly to obtain a mixed sol. Immerse the rice husk activated carbon powder in the mixed sol under the condition of a vacuum degree of -0.1 - -0.05 MPa for 30 - 60 min, then dry it at 100 - 110 °C for 10 - 12 h, and then heat-treat it in an air atmosphere at 900 - 1200 °C for 1 - 3 h, grind and screen to obtain porous powder particles containing mullite whiskers with a particle size less than 0.088 mm.

[0031] Step 2: Mix 20 - 40 wt% of the porous powder particles containing mullite whiskers, 20 - 40 wt% of sodium chloride powder and 20 - 60 wt% of potassium chloride powder evenly to obtain mixture I. Heat-treat mixture I in an air atmosphere at 700 - 900 °C for 2 - 4 h, grind and screen to obtain modified eutectic salt powder with a particle size less than 0.088 mm.

[0032] Step 3: Mix 30 - 40 wt% of alumina micro-powder, 8 - 22 wt% of tabular corundum powder, 40 - 50 wt% of modified eutectic salt powder, and 2 - 8 wt% of aluminum dihydrogen phosphate powder evenly to obtain mixture II; press mixture II under the condition of 40 - 60 MPa, and perform heat treatment at 700 - 800 °C for 2 - 4 h in an air atmosphere to prepare a composite high-temperature phase change heat storage material.

[0033] The chemical components of the aluminum sol are: the content of Al2(SO4)3 is greater than 14.50 wt%; the pH of the aluminum sol is 7 - 9.

[0034] The chemical components of the silica sol are: the content of SiO2 is greater than 25.50 wt%; the pH of the silica sol is 8.5 - 9.5.

[0035] The chemical components of the rice husk activated carbon powder are: the C content is 20 - 40 wt%, the SiO2 content is 20 - 40 wt%, and the loss on ignition is 50 - 60 wt%.

[0036] In this specific embodiment:

[0037] The average particle size of the aluminum sol particles is 8 - 25 nm.

[0038] The average particle size of the silica sol particles is 8 - 25 nm.

[0039] The aluminum fluoride powder is of analytical purity; the AlF3 content of the aluminum fluoride powder is greater than 99 wt%.

[0040] The particle size of the rice husk activated carbon powder is less than 0.088 mm, and the average pore diameter of the rice husk activated carbon powder is 10 μm.

[0041] The particle size of the sodium chloride powder is less than 0.088 mm; the NaCl content of the sodium chloride powder is greater than 99 wt%.

[0042] The particle size of the potassium chloride powder is less than 0.088 mm; the KCl content of the potassium chloride powder is greater than 99 wt%.

[0043] The particle size of the alumina micro-powder is 1 - 2 μm; the Al2O3 content of the alumina micro-powder is greater than 99 wt%.

[0044] The particle size of the tabular corundum powder is less than 0.045 mm; the Al2O3 content of the tabular corundum is greater than 99 wt%.

[0045] The particle size of the aluminum dihydrogen phosphate powder is less than 0.088 mm; the Al(H2PO4)3 content of the aluminum dihydrogen phosphate is greater than 99 wt%.

[0046] Details in the examples will not be elaborated again.

[0047] Example 1

[0048] A composite high-temperature phase change heat storage material and a preparation method thereof. The preparation method described in this example is as follows:

[0049] Step 1: Mix 52 wt% of aluminum sol, 40 wt% of silica sol, and 8 wt% of aluminum fluoride powder evenly to obtain a mixed sol. Immerse the rice husk activated carbon powder in the mixed sol under a vacuum of -0.1 MPa for 30 min, then dry it at 100 °C for 10 h, and then heat-treat it in an air atmosphere at 900 °C for 1 h, grind it, and sieve it to obtain porous powder particles containing mullite whiskers with a particle size less than 0.088 mm.

[0050] Step 2: Mix 20 wt% of the porous powder particles containing mullite whiskers, 20 wt% of sodium chloride powder, and 60 wt% of potassium chloride powder evenly to obtain mixture I. Heat-treat mixture I in an air atmosphere at 700 °C for 2 h, grind it, and sieve it to obtain modified eutectic salt powder with a particle size less than 0.088 mm.

[0051] Step 3: Mix 30 wt% of alumina micropowder, 22 wt% of tabular corundum powder, 40 wt% of the modified eutectic salt powder, and 8 wt% of aluminum dihydrogen phosphate powder evenly to obtain mixture II; press mixture II into a shape at 40 MPa, and heat-treat it in an air atmosphere at 700 °C for 2 h to obtain the composite high-temperature phase change heat storage material.

[0052] The chemical components of the aluminum sol are: the content of Al2(SO4)3 is 14.7 wt%; the pH of the aluminum sol is 7.

[0053] The chemical components of the silica sol are: the content of SiO2 is 25.7 wt%; the pH of the silica sol is 8.5.

[0054] The chemical components of the rice husk activated carbon powder are: the C content is 20 wt%, the SiO2 content is 40 wt%, and the loss on ignition is 50 wt%.

[0055] The use temperature range of the composite high-temperature phase change heat storage material prepared in this example is 600 - 800 °C. The main properties of the composite high-temperature phase change heat storage material are detected as follows: the bulk density is 2.99 g / cm 3 ; the thermal conductivity is 2.6 W / (m·K); the thermal shock stability is 32 times (800 °C, air cooling); the compressive strength is 56.3 MPa; no new phase is generated after 100 thermal cycles, and the mass loss rate is 0.11 wt% (600 - 800 °C); the heat storage density is 253.3 kJ / kg (600 - 800 °C).

[0056] Example 2

[0057] A composite high-temperature phase change heat storage material and a preparation method thereof. The preparation method described in this embodiment is as follows:

[0058] Step 1: Mix 58 wt% of aluminum sol, 36 wt% of silica sol, and 6 wt% of aluminum fluoride powder evenly to obtain a mixed sol. Immerse the rice husk activated carbon powder in the mixed sol under a vacuum degree of -0.07 MPa for 40 min, then dry it at 105 °C for 11 h, and then heat-treat it in an air atmosphere at 1000 °C for 2 h, grind it, and screen it to obtain porous powder particles containing mullite whiskers with a particle size less than 0.088 mm.

[0059] Step 2: Mix 26 wt% of the porous powder particles containing mullite whiskers, 28 wt% of sodium chloride powder, and 46 wt% of potassium chloride powder evenly to obtain mixture I. Heat-treat mixture I in an air atmosphere at 800 °C for 3 h, grind it, and screen it to obtain modified eutectic salt powder with a particle size less than 0.088 mm.

[0060] Step 3: Mix 33 wt% of alumina micropowder, 18 wt% of tabular corundum powder, 43 wt% of the modified eutectic salt powder, and 6 wt% of aluminum dihydrogen phosphate powder evenly to obtain mixture II; press mixture II into a mold under a pressure of 45 MPa, and heat-treat it in an air atmosphere at 750 °C for 3 h to prepare the composite high-temperature phase change heat storage material.

[0061] The chemical components of the aluminum sol are as follows: the content of Al2(SO4)3 is 15.1 wt%; the pH of the aluminum sol is 7.8.

[0062] The chemical components of the silica sol are as follows: the content of SiO2 is 26.2 wt%; the pH of the silica sol is 8.9.

[0063] The chemical components of the rice husk activated carbon powder are as follows: the C content is 26.4 wt%, the SiO2 content is 32.9 wt%, and the loss on ignition is 53.5 wt%.

[0064] The service temperature range of the composite high-temperature phase change heat storage material prepared in this embodiment is 600 - 800 °C. The main properties of the composite high-temperature phase change heat storage material are detected as follows: the bulk density is 3.12 g / cm 3 ; the thermal conductivity is 2.4 W / (m·K); the thermal shock stability is 30 times (800 °C, air cooling); the compressive strength is 57.5 MPa; no new phase is generated after 100 thermal cycles, and the mass loss rate is 0.08 wt% (600 - 800 °C); the heat storage density is 261.7 kJ / kg (600 - 800 °C).

[0065] Example 3

[0066] A composite high-temperature phase change heat storage material and its preparation method. The preparation method described in this embodiment is as follows:

[0067] Step 1: Mix 63 wt% of aluminum sol, 33 wt% of silica sol, and 4 wt% of aluminum fluoride powder evenly to obtain a mixed sol. Immerse the rice husk activated carbon powder in the mixed sol under a vacuum of -0.07 MPa for 50 min, then dry it at 105 °C for 11 h, and then heat-treat it in an air atmosphere at 1100 °C for 2.5 h, grind it, and sieve it to obtain porous powder particles containing mullite whiskers with a particle size less than 0.088 mm.

[0068] Step 2: Mix 33 wt% of the porous powder particles containing mullite whiskers, 33 wt% of sodium chloride powder, and 34 wt% of potassium chloride powder evenly to obtain mixture I. Heat-treat mixture I in an air atmosphere at 900 °C for 3.5 h, grind it, and sieve it to obtain modified eutectic salt powder with a particle size less than 0.088 mm.

[0069] Step 3: Mix 36 wt% of alumina micropowder, 13 wt% of tabular corundum powder, 47 wt% of the modified eutectic salt powder, and 4 wt% of aluminum dihydrogen phosphate powder evenly to obtain mixture II; press mixture II into a mold under a pressure of 50 MPa, and heat-treat it in an air atmosphere at 800 °C for 3.5 h to prepare the composite high-temperature phase change heat storage material.

[0070] The chemical components of the aluminum sol are: the content of Al2(SO4)3 is 16.2 wt%; the pH of the aluminum sol is 8.2.

[0071] The chemical components of the silica sol are: the content of SiO2 is 26.8 wt%; the pH of the silica sol is 9.

[0072] The chemical components of the rice husk activated carbon powder are: the C content is 33.6 wt%, the SiO2 content is 27.6 wt%, and the loss on ignition is 57.2 wt%.

[0073] The use temperature range of the composite high-temperature phase change heat storage material prepared in this embodiment is 600 - 800 °C. The main properties of the composite high-temperature phase change heat storage material are detected as follows: the bulk density is 2.89 g / cm 3 ; the thermal conductivity is 2.5 W / (m·K); the thermal shock stability is 33 times (800 °C, air cooling); the compressive strength is 55.8 MPa; no new phase is generated after 100 thermal cycles, and the mass loss rate is 0.09 wt% (600 - 800 °C); the heat storage density is 268.4 kJ / kg (600 - 800 °C).

[0074] Example 4

[0075] A composite high-temperature phase change heat storage material and a preparation method thereof. The preparation method described in this embodiment is as follows:

[0076] Step 1: Mix 68 wt% of aluminum sol, 30 wt% of silica sol, and 2 wt% of aluminum fluoride powder evenly to obtain a mixed sol. Immerse the rice husk activated carbon powder in the mixed sol under a vacuum degree of -0.05 MPa for 60 min, then dry it at 110°C for 12 h, and then heat-treat it in an air atmosphere at 1200°C for 3 h, grind it, and sieve it to obtain porous powder particles containing mullite whiskers with a particle size less than 0.088 mm.

[0077] Step 2: Mix 40 wt% of the porous powder particles containing mullite whiskers, 40 wt% of sodium chloride powder, and 20 wt% of potassium chloride powder evenly to obtain mixture I. Heat-treat mixture I in an air atmosphere at 900°C for 4 h, grind it, and sieve it to obtain modified eutectic salt powder with a particle size less than 0.088 mm.

[0078] Step 3: Mix 40 wt% of alumina micropowder, 8 wt% of tabular corundum powder, 50 wt% of the modified eutectic salt powder, and 2 wt% of aluminum dihydrogen phosphate powder evenly to obtain mixture II; press mixture II into a mold under 60 MPa, and heat-treat it in an air atmosphere at 800°C for 4 h to prepare the composite high-temperature phase change heat storage material.

[0079] The chemical components of the aluminum sol are: the content of Al2(SO4)3 is 16.5 wt%; the pH of the aluminum sol is 9.

[0080] The chemical components of the silica sol are: the content of SiO2 is 27.1 wt%; the pH of the silica sol is 9.5.

[0081] The chemical components of the rice husk activated carbon powder are: the C content is 40 wt%, the SiO2 content is 20 wt%, and the loss on ignition is 60 wt%.

[0082] The service temperature range of the composite high-temperature phase change heat storage material prepared in this embodiment is 600 - 800°C. The main properties of the composite high-temperature phase change heat storage material are detected as follows: the bulk density is 2.73 g / cm 3 ; the thermal conductivity is 2.2 W / (m·K); the thermal shock stability is 28 times (800°C, air cooling); the compressive strength is 51.3 MPa; no new phase is generated after 100 thermal cycles, and the mass loss rate is 0.07 wt% (600 - 800°C); the heat storage density is 280.9 kJ / kg (600 - 800°C).

[0083] The following are the positive effects of this specific embodiment compared with the prior art:

[0084] (1) This specific embodiment defines the particle gradation of the raw materials. By the binding effect of aluminum dihydrogen phosphate during the heat treatment of the composite material, the densification of the composite high-temperature phase change heat storage material is promoted, the mechanical properties of the composite high-temperature phase change heat storage material are improved, and the prepared composite high-temperature phase change heat storage material has high compressive strength. At the same time, by limiting the particle gradation, the internal pore size of the composite high-temperature phase change heat storage material is small, and mullite whiskers are in-situ synthesized in the inorganic salt, hindering the migration of molten salt at high temperature, and thus making it difficult for the molten salt to leak during the thermal cycle. The prepared composite high-temperature phase change heat storage material has high compressive strength and good cycle stability.

[0085] (2) This specific embodiment utilizes the burnout of rice husk activated carbon and the catalytic characteristics of aluminum fluoride powder during the heat treatment process, fully retaining the pore structure of the rice husk activated carbon, enabling mullite whiskers to grow with the rice husk activated carbon as a template. And during the subsequent heat treatment process, the mullite whiskers further interweave and grow in the inorganic salt, forming a stable network structure, which can relieve the mechanical stress caused by the expansion and contraction of the inorganic salt. Combining with the good thermal shock resistance of the mullite whiskers themselves, the prepared composite high-temperature phase change heat storage material has excellent thermal shock stability.

[0086] (3) This specific embodiment makes full use of the characteristic of high thermal conductivity of alumina. Through particle packing, a high degree of densification is achieved, effectively improving the heat transfer ability of the composite high-temperature phase change heat storage material. At the same time, an interwoven whisker structure is formed in the inorganic salt, effectively reducing the interfacial thermal resistance between inorganic salt particles and improving the heat transfer efficiency. The prepared composite high-temperature phase change heat storage material has excellent thermal conductivity.

[0087] The service temperature range of the composite high-temperature phase change heat storage material prepared by this specific embodiment is 600 - 800 °C. The main properties of the composite high-temperature phase change heat storage material are detected as follows: bulk density ≥ 2.73 g / cm 3 ; thermal conductivity ≥ 2.2 W / (m·K); thermal shock stability ≥ 28 times (800 °C, air cooling); compressive strength ≥ 51.3 MPa; no new phase is generated after 100 thermal cycles, and the mass loss rate ≤ 0.11 wt% (600 - 800 °C); heat storage density ≥ 253.3 kJ / kg (600 - 800 °C).

[0088] The detection standards for the performance indicators involved in this specific embodiment: the bulk density is measured in accordance with GB / T2999 - 2016; the thermal conductivity is measured in accordance with the standard of GB / T5990 - 2021; the thermal shock stability is measured in accordance with GB / T30873 - 2014; the compressive strength is measured in accordance with GB / T5072 - 2023.

[0089] Therefore, the composite high-temperature phase change heat storage material prepared by this specific embodiment has excellent thermal shock stability, high compressive strength, good cycle stability, and excellent thermal conductivity.

Claims

1. A preparation method of a composite high-temperature phase change heat storage material, characterized in that, The steps of the preparation method are as follows: Step 1: Mix 52 - 68 wt% of aluminum sol, 30 - 40 wt% of silica sol, and 2 - 8 wt% of aluminum fluoride powder evenly to obtain a mixed sol; Immerse the rice husk activated carbon powder in the mixed sol under the condition of a vacuum degree of -0.1 to -0.05 MPa for 30 - 60 min, then dry it at 100 - 110 °C for 10 - 12 h, and then heat-treat it in an air atmosphere at 900 - 1200 °C for 1 - 3 h, grind it, and sieve it to obtain porous powder particles containing mullite whiskers with a particle size less than 0.088 mm; Step 2: Mix 20 - 40 wt% of the porous powder particles containing mullite whiskers, 20 - 40 wt% of sodium chloride powder, and 20 - 60 wt% of potassium chloride powder evenly to obtain mixture I, heat-treat mixture I in an air atmosphere at 700 - 900 °C for 2 - 4 h, grind it, and sieve it to obtain modified eutectic salt powder with a particle size less than 0.088 mm; Step 3: Mix 30 - 40 wt% of alumina micropowder, 8 - 22 wt% of tabular corundum powder, 40 - 50 wt% of modified eutectic salt powder, and 2 - 8 wt% of aluminum dihydrogen phosphate powder evenly to obtain mixture II; Press mixture II into a shape under the condition of 40 - 60 MPa, and heat-treat it in an air atmosphere at 700 - 800 °C for 2 - 4 h to prepare a composite high-temperature phase change heat storage material.

2. The preparation method of the composite high-temperature phase change heat storage material according to claim 1, characterized in that The average particle size of the colloidal particles of the aluminum sol is 8 - 25 nm; The chemical composition of the aluminum sol is: the content of Al2(SO4)3 is greater than 14.50 wt%; The pH of the aluminum sol is 7 - 9.

3. The preparation method of the composite high-temperature phase change heat storage material according to claim 1, characterized in that The average particle size of the colloidal particles of the silica sol is 8 - 25 nm; The chemical composition of the silica sol is: the content of SiO2 is greater than 25.50 wt%; The pH of the silica sol is 8.5 - 9.

5.

4. The preparation method of the composite high-temperature phase change heat storage material according to claim 1, wherein The aluminum fluoride powder is of analytical purity; The AlF3 content of the aluminum fluoride powder is greater than 99 wt%.

5. The preparation method of the composite high-temperature phase change heat storage material according to claim 1, wherein The particle size of the rice husk activated carbon powder is less than 0.088 mm, and the average pore diameter of the rice husk activated carbon powder is 10 μm; The chemical composition of the rice husk activated carbon powder is: the C content is 20 - 40 wt%, the SiO2 content is 20 - 40 wt%, and the loss on ignition is 50 - 60 wt%.

6. The preparation method of the composite high-temperature phase change heat storage material according to claim 1, wherein, The particle size of the sodium chloride powder is less than 0.088 mm; The NaCl content of the sodium chloride powder is greater than 99 wt%.

7. The preparation method of the composite high-temperature phase change heat storage material according to claim 1, characterized in that, The particle size of the potassium chloride powder is less than 0.088 mm; The KCl content of the potassium chloride powder is greater than 99 wt%.

8. The preparation method of the composite high-temperature phase change heat storage material according to claim 1, characterized in that, The particle size of the alumina micropowder is 1 - 2 μm; The Al2O3 content of the alumina micropowder is greater than 99 wt%.

9. The preparation method of the composite high-temperature phase change heat storage material according to claim 1, characterized in that, The particle size of the tabular corundum powder is less than 0.045 mm; The Al2O3 content of the tabular corundum is greater than 99 wt%.

10. The preparation method of the composite high-temperature phase change heat storage material according to claim 1, wherein The particle size of the aluminum dihydrogen phosphate powder is less than 0.088 mm; The Al(H2PO4)3 content of the aluminum dihydrogen phosphate is greater than 99 wt%.

11. A composite high-temperature phase change heat storage material, characterized in that The composite high-temperature phase change heat storage material is the composite high-temperature phase change heat storage material prepared according to the preparation of the composite high-temperature phase change heat storage material described in any one of claims 1 - 10.