Rapid heat storage type cement-based heat storage material and preparation method thereof
By incorporating C-PCM@SiO2 composite microcapsules with graphite and paraffin-based phase change materials, the thermal conductivity and storage rate of water cement-based materials are enhanced, addressing cost and strength concerns in existing technologies.
Patent Information
- Application Number
- CN202510634301.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-16
- Publication Date
- 2025-07-15
AI Technical Summary
Existing cement-based heat storage materials have problems such as poor thermal conductivity and slow heat storage speed. The addition of carbon nanotubes, carbon fibers, graphene and other carbon materials will lead to high costs and reduced cement strength.
C-PCM@SiO2 composite microcapsules with graphite and paraffin-based phase change materials as core materials and amorphous silica as capsule walls were introduced, and were prepared through the principle of interface polymerization to improve thermal conductivity and maintain cement strength.
The thermal conductivity and heat storage performance of cement-based heat storage materials is significantly improved, the early compressive strength and flow of cement are maintained, and the latent heat capacity of the phase change is almost unchanged after 150 phase transition cycles, and it has good thermal reliability and temperature change resistance.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of cement-based heat storage materials, and particularly relates to a rapid heat storage type cement-based heat storage material and a preparation method thereof. Background Art
[0002] With the continuous advancement of the urbanization process, urban buildings consume a large amount of energy, which will lead to a series of resource and environmental problems. At present, building energy consumption has become one of the main energy consumption ways in China, which will directly affect the green and sustainable development of human society. Building energy conservation is one of the most effective means to reduce building energy consumption and regulate energy supply, and developing building energy-saving materials is the key to achieving building energy conservation. Cement-based heat storage materials can improve the heat storage capacity of building materials, absorb and release heat energy at almost constant temperatures, alleviate daily temperature changes, and thus reduce building energy consumption. They are excellent building energy-saving materials and have broad application prospects in the field of building energy conservation.
[0003] Cement-based heat storage materials are made to have the function of storing and releasing heat energy by adding phase change materials, high heat capacity materials to the cement matrix or changing the cement hydration reaction, etc. However, the cement-based heat storage materials prepared at present have problems such as poor thermal conductivity and slow heat storage speed. At present, the main method to solve this problem is to add carbon materials such as carbon nanotubes, carbon fibers, and graphene to the cement-based heat storage materials to improve their thermal conductivity. However, on the one hand, the cost of these carbon materials is too high, and on the other hand, it is easy to cause the problem of the decrease in the strength of the cement-based energy storage materials. Therefore, how to solve the problem of poor thermal conductivity of cement-based heat storage materials on the premise of low cost without bringing new problems such as damage to the cement strength is the current technical difficulty. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a rapid heat storage type cement-based heat storage material and a preparation method thereof in view of the problems existing in the prior art. C-PCM@SiO2 composite microcapsules with graphite and paraffin-based phase change materials as the core and amorphous silica as the capsule wall are introduced into the cement, while improving the thermal conductivity and heat storage performance, it has no adverse effect on the cement strength and fluidity, and the prepared cement-based heat storage material has reliable rapid heat storage performance.
[0005] To solve the technical problems proposed by the present invention, the present invention provides a rapid heat storage type cement-based heat storage material, which comprises the following raw materials in parts by mass: 100 parts of cement, 2 - 10 parts of C-PCM@SiO2 composite microcapsules, and 40 - 60 parts of water.
[0006] In the above solution, the cement is ordinary Portland cement.
[0007] In the above solution, the average particle size of the C-PCM@SiO2 composite microcapsules is 0.5 to 2 μm, the core material is graphite and paraffin-based phase change material, the capsule wall is amorphous silica, its thermal conductivity is 0.5 to 3 W / mK, and the phase change latent heat is 60 to 110 J / g.
[0008] In the above solution, the preparation method of the C-PCM@SiO2 composite microcapsules includes the following steps:
[0009] 1) Add the paraffin-based phase change material to anhydrous ethanol and water, heat and stir to melt and disperse it, and then lower the temperature and solidify it to obtain paraffin-based phase change material particles;
[0010] 2) Mix epoxy resin, γ-aminopropyltriethoxysilane, polyvinyl alcohol and water, and heat and stir to obtain mixture A;
[0011] 3) Mix mixture A, paraffin-based phase change material particles and graphite evenly to obtain mixture B;
[0012] 4) Mix mixture B and tetraethyl orthosilicate evenly to obtain mixture C;
[0013] 5) Mix water, cetyltrimethylammonium bromide and anhydrous ethanol evenly to obtain mixture D;
[0014] 6) Mix mixture C and mixture D, first stir at high speed and then perform ultrasonic treatment, and then add ammonia water and stir to react to obtain C-PCM@SiO2 composite microcapsules.
[0015] In the above solution, the paraffin-based phase change material is one of n-hexadecane, n-octadecane, n-eicosane, and n-docosane.
[0016] In the above solution, in step 1), the mass ratio of the paraffin-based phase change material, anhydrous ethanol and water is 1:(2 - 5):(10 - 20).
[0017] In the above solution, in step 1), the temperature of heating and stirring is 5 to 10 °C higher than the melting point temperature of the paraffin-based phase change material, the stirring speed is 300 to 500 r / min, the stirring time is 30 to 35 min, and the subsequent temperature is lowered to 5 to 10 °C below the melting point temperature of the paraffin-based phase change material.
[0018] In the above solution, the epoxy equivalent of the epoxy resin is 210 to 250 g / eq.
[0019] In the above solution, in step 2), the mass ratio of epoxy resin, γ-aminopropyltriethoxysilane, polyvinyl alcohol and water is 1:(0.1 - 0.15):(10 - 12):(100 - 110).
[0020] In the above solution, in step 2), the temperature for heating and stirring is 93 - 98 °C, the stirring speed is 300 - 500 r / min, and the stirring time is 4 - 6 h.
[0021] In the above solution, the particle size of the graphite ≤ 1 μm, and spherical graphite with a particle size ≤ 25 nm is preferably used.
[0022] In the above solution, in step 3), the mass ratio of mixture A, paraffin - based phase - change material particles, and graphite is 1:(8 - 12):(7 - 10).
[0023] In the above solution, in step 4), the mass ratio of mixture B to tetraethyl orthosilicate is (0.8 - 1.2):1, and the temperature is controlled at 20 - 60 °C during mixing.
[0024] In the above solution, in step 5), the mass ratio of water, cetyltrimethylammonium bromide, and absolute ethanol is (1.5 - 2):(0.01 - 0.015):1.
[0025] In the above solution, the mass ratio of mixture C to mixture D is 1:(17 - 25).
[0026] In the above solution, the temperature is controlled to be 5 - 10 °C higher than the melting point temperature of the paraffin - based phase - change material throughout step 6).
[0027] In the above solution, the stirring speed for high - speed stirring is 800 - 1500 r / min, and the stirring time is 5 - 10 min.
[0028] In the above solution, the ultrasonic power for ultrasonic treatment is 600 - 800 W, and the ultrasonic time is 5 - 15 min.
[0029] In the above solution, the mass concentration of the ammonia water is 25 - 28%, and the mass ratio of ammonia water to the water in step 5) is 1:(100 - 150).
[0030] In the above solution, the stirring speed for the stirring reaction is 500 - 800 r / min, and the reaction time is 16 - 24 h.
[0031] The present invention also provides a preparation method of a fast heat - storage type cement - based heat - storage material, comprising the following steps:
[0032] First, mix cement and C - PCM@SiO2 composite micro - capsules evenly, and then add water and mix evenly to obtain the fast heat - storage type cement - based heat - storage material.
[0033] In the above solution, the fluidity of the fast heat storage type cement-based heat storage material is ≥190 mm, the thermal conductivity is 0.91 - 1.61 W / m·K, the 3d compressive strength is 20 - 35 MPa, which is 1 - 1.4 times that of ordinary Portland cement, the 28d compressive strength is 40 - 55 MPa, which is 90 - 120% of ordinary Portland cement, and the latent heat loss of phase change after 150 phase change cycles is ≤2.5%.
[0034] The main technical concept of the present invention is as follows:
[0035] Based on the need to improve the thermal conductivity and heat storage speed of the cement-based heat storage material, the present invention introduces paraffin-based phase change material and graphite into the cement-based heat storage material. However, direct addition will cause a decrease in the strength and fluidity of the cement-based heat storage material. Therefore, based on the interfacial polymerization principle, the present invention performs silica coating modification on graphite and paraffin-based phase change material to prepare C-PCM@SiO2 composite microcapsules with graphite and paraffin-based phase change material as the core material and amorphous silica as the capsule wall. During the coating process, through the melting-re-solidification treatment of the paraffin-based phase change material, the structure becomes more regular, the surface roughness is reduced, a smooth interface is provided for subsequent coating, and at the same time, the purity of the phase change material can be improved. Then, a binder is used to prevent the aggregation of paraffin-based phase change material and graphite, and finally, C-PCM@SiO2 composite microcapsules are successfully prepared.
[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0037] 1) The present invention introduces a special C-PCM@SiO2 composite microcapsule with graphite and paraffin-based phase change material as the core material and amorphous silica as the capsule wall into the cement. This microcapsule has good thermal conductivity, and after addition, it can significantly improve the thermal conductivity and heat storage performance. The capsule has good compatibility with the cement-based material, has good hydration activity, and the amorphous SiO2 attached to the surface can improve the early compressive strength of the cement, and at the same time will not have an adverse impact on the later compressive strength and fluidity. Finally, the prepared cement-based heat storage material has reliable fast heat storage performance, and after 150 phase change cycles, there is no leakage of the phase change material, and the latent heat capacity of the phase change hardly changes, showing good thermal reliability and temperature change resistance.
[0038] 2) The preparation process of the C-PCM@SiO2 composite microcapsule of the present invention is simple, does not require synthesis conditions such as high temperature and high pressure, and does not require too many types of organic reagents, effectively solving the problem of too high cost of carbon materials such as carbon fiber, carbon nanotube, and graphene used to improve the performance of cement-based heat storage materials, and at the same time can avoid environmental problems caused by chemical reagents and energy consumption. Specific embodiments
[0039] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments. However, the content of the present invention is not limited to the following embodiments only.
[0040] In the following embodiments, the epoxy resin used is E-44 epoxy resin with an epoxy equivalent of 210 - 240 g / eq; the graphite used is spherical graphite with a particle size ≤ 25 nm.
[0041] Example 1
[0042] 1) Add 40 parts of n-hexadecane to 100 parts of absolute ethanol and 600 parts of deionized water (the mass ratio of n-hexadecane, absolute ethanol, and deionized water is 1:2.5:15), heat to 25°C, stir at a rate of 500 r / min for 30 min to melt it, then lower the temperature to 10°C to solidify it again. After filtration, washing, and drying, n-hexadecane particles are obtained;
[0043] 2) Mix 40 parts of epoxy resin, 4 parts of γ-aminopropyltriethoxysilane, 400 parts of polyvinyl alcohol, and 4000 parts of deionized water (the mass ratio of epoxy resin, γ-aminopropyltriethoxysilane, polyvinyl alcohol, and water is 1:0.1:10:100), heat to 95°C, and stir at a rate of 500 r / min for 4 h to obtain mixture A;
[0044] 3) Mix 4 parts of mixture A, 40 parts of n-hexadecane particles, and 40 parts of graphite evenly (the mass ratio of mixture A, n-hexadecane particles, and graphite is 1:10:10) to obtain mixture B;
[0045] 4) Mix 40 parts of mixture B and 50 parts of tetraethyl orthosilicate evenly at 35°C (the mass ratio of mixture B to tetraethyl orthosilicate is 0.8:1) to obtain mixed liquid C;
[0046] 5) Mix 1125 parts of deionized water, 9 parts of cetyltrimethylammonium bromide, and 750 parts of absolute ethanol evenly at room temperature (the mass ratio of deionized water, cetyltrimethylammonium bromide, and absolute ethanol is 1.5:0.012:1) to obtain mixed liquid D;
[0047] 6) Under the condition of a 25°C constant temperature water bath, mix mixed liquid C and mixed liquid D (the mass ratio of mixed liquid C to mixed liquid D is 1:21). First, stir at a high speed of 1000 r / min for 5 min, then ultrasonicate at an ultrasonic power of 800 W for 10 min. Then add 10 parts of 25% ammonia water by mass (the mass ratio of ammonia water to the deionized water in step 5 is 1:112.5), stir and react at a rate of 500 r / min for 24 h. After the reaction is completed, take out the mixed liquid, perform suction filtration, washing, and drying to obtain C-PCM@SiO2 composite microcapsules;
[0048] 7) Take 100 parts of cement and 2 parts of C-PCM@SiO2 composite microcapsules and mix them evenly, then add 60 parts of tap water and mix evenly to obtain a rapid heat storage type cement-based heat storage material.
[0049] Comparative Example 1-1
[0050] Take 100 parts of cement and add 60 parts of tap water and mix evenly to obtain a cement-based material.
[0051] Comparative Example 1-2
[0052] Do not perform steps 1) to 3), replace 40 parts of mixture B in step 4) with 40 parts of graphite and perform subsequent operations to prepare C@SiO2 composite microcapsules;
[0053] Do not perform steps 1) to 3), replace 40 parts of mixture B in step 4) with 40 parts of n-hexadecane and perform subsequent operations to prepare PCM@SiO2 composite microcapsules;
[0054] Take 100 parts of cement, 1 part of C@SiO2 composite microcapsules, and 1 part of PCM@SiO2 composite microcapsules and mix them evenly, then add 60 parts of tap water and mix evenly to obtain a rapid heat storage type cement-based heat storage material.
[0055] Comparative Example 1-3
[0056] Do not perform steps 1) to 3), replace 40 parts of mixture B in step 4) with 40 parts of n-hexadecane and perform subsequent operations to prepare PCM@SiO2 composite microcapsules;
[0057] Take 100 parts of cement, 1 part of graphite, and 1 part of PCM@SiO2 composite microcapsules and mix them evenly, then add 60 parts of tap water and mix evenly to obtain a rapid heat storage type cement-based heat storage material.
[0058] Example 2
[0059] 1) Add 50 parts of n-octadecane to 250 parts of absolute ethanol and 1000 parts of deionized water (the mass ratio of n-octadecane, absolute ethanol, and deionized water is 1:5:20), heat to 35 °C and stir at a rate of 350 r / min for 30 min to melt it, then lower the temperature to 25 °C to solidify it again, filter, wash, and dry to obtain n-octadecane particles;
[0060] 2) Mix 50 parts of epoxy resin, 5 parts of γ-aminopropyltriethoxysilane, 500 parts of polyvinyl alcohol, and 5000 parts of deionized water (the mass ratio of epoxy resin, γ-aminopropyltriethoxysilane, polyvinyl alcohol, and water is 1:0.1:10:100), heat to 96 °C and stir at a rate of 400 r / min for 4 h to obtain mixture A;
[0061] 3) Mix 5 parts of mixture A, 50 parts of n-octadecane particles, and 50 parts of graphite evenly (the mass ratio of mixture A, n-octadecane particles, and graphite is 1:10:10) to obtain mixture B;
[0062] 4) Mix 50 parts of mixture B and 60 parts of tetraethyl orthosilicate evenly by stirring at 35 °C (the mass ratio of mixture B to tetraethyl orthosilicate is 0.83:1) to obtain mixture C;
[0063] 5) Mix 1300 parts of deionized water, 8 parts of cetyltrimethylammonium bromide, and 800 parts of absolute ethanol evenly by stirring at room temperature (the mass ratio of deionized water, cetyltrimethylammonium bromide, and absolute ethanol is 1.63:0.01:1) to obtain mixture D;
[0064] 6) Under the condition of a 35 °C constant temperature water bath, mix mixture C and mixture D (the mass ratio of mixture C to mixture D is 1:19), first stir at a high speed of 1200 r / min for 8 min, then ultrasonicate at an ultrasonic power of 750 W for 10 min, then add 10 parts of 25% ammonia water by mass (the mass ratio of ammonia water to the deionized water in step 5 is 1:130), stir and react at a rate of 800 r / min for 18 h. After the reaction is completed, take out the mixture, carry out suction filtration, washing, and drying to obtain C-PCM@SiO2 composite microcapsules;
[0065] 7) Take 100 parts of cement and 6 parts of C-PCM@SiO2 composite microcapsules, mix them evenly, and then add 60 parts of tap water and mix evenly to obtain a fast heat storage type cement-based heat storage material.
[0066] Comparative Example 2-1
[0067] Take 100 parts of cement, add 60 parts of tap water, and mix evenly to obtain a cement-based material.
[0068] Comparative Example 2-2
[0069] Without performing steps 1) to 3), replace 50 parts of mixture B in step 4) with 50 parts of graphite and perform subsequent operations to prepare C@SiO2 composite microcapsules;
[0070] Without performing steps 1) to 3), replace 50 parts of mixture B in step 4) with 50 parts of n-octadecane and perform subsequent operations to prepare PCM@SiO2 composite microcapsules;
[0071] Take 100 parts of cement, 3 parts of C@SiO2 composite microcapsules, and 3 parts of PCM@SiO2 composite microcapsules, mix them evenly, and then add 60 parts of tap water and mix evenly to obtain a fast heat storage type cement-based heat storage material.
[0072] Example 3
[0073] 1) Add 60 parts of n - eicosane to 120 parts of absolute ethanol and 1000 parts of deionized water (the mass ratio of n - eicosane, absolute ethanol and deionized water is 1:2:17), heat to 48 °C and stir at a rate of 400 r / min for 30 min to melt it, then lower the temperature to 30 °C to solidify it again. After filtration, washing and drying, n - eicosane particles are obtained;
[0074] 2) Mix 45 parts of epoxy resin, 5 parts of γ - aminopropyltriethoxysilane, 450 parts of polyvinyl alcohol and 4500 parts of deionized water (the mass ratio of epoxy resin, γ - aminopropyltriethoxysilane, polyvinyl alcohol and water is 1:0.11:10:100), heat to 95 °C and stir at a rate of 350 r / min for 4.5 h to obtain mixture A;
[0075] 3) Mix 5 parts of mixture A, 40 parts of n - eicosane particles and 60 parts of graphite evenly (the mass ratio of mixture A, n - eicosane particles and graphite is 1:12:8) to obtain mixture B;
[0076] 4) Mix 60 parts of mixture B and 50 parts of tetraethyl orthosilicate evenly at 30 °C (the mass ratio of mixture B to tetraethyl orthosilicate is 1.2:1) to obtain mixture C;
[0077] 5) Mix 1200 parts of deionized water, 12 parts of cetyltrimethylammonium bromide and 800 parts of absolute ethanol evenly at room temperature (the mass ratio of deionized water, cetyltrimethylammonium bromide and absolute ethanol is 1.5:0.015:1) to obtain mixture D;
[0078] 6) Under the condition of a 48 °C constant - temperature water bath, mix mixture C and mixture D (the mass ratio of mixture C to mixture D is 1:18.2). First, stir at a high speed of 1000 r / min for 10 min, then ultrasonicate at an ultrasonic power of 600 W for 15 min. Then add 10 parts of 25% ammonia water (the mass ratio of ammonia water to the deionized water in step 5 is 1:120) and stir at a rate of 500 r / min for 24 h. After the reaction is completed, take out the mixture, perform suction filtration, washing and drying to obtain C - PCM@SiO2 composite microcapsules;
[0079] 7) Take 100 parts of cement and 5 parts of C - PCM@SiO2 composite microcapsules and mix them evenly, then add 42 parts of tap water and mix evenly to obtain a rapid heat - storage type cement - based heat - storage material.
[0080] Comparative Example 3 - 1
[0081] Take 100 parts of cement and add 42 parts of tap water and mix evenly to obtain a cement - based material.
[0082] Comparative Example 3-2
[0083] Steps 1) to 3) were not carried out, and 60 parts of mixture B in step 4) was replaced with 60 parts of graphite for subsequent operations to prepare C@SiO2 composite microcapsules;
[0084] Steps 1) to 3) were not carried out, and 60 parts of mixture B in step 4) was replaced with 60 parts of n-eicosane for subsequent operations to prepare PCM@SiO2 composite microcapsules;
[0085] 100 parts of cement, 3 parts of C@SiO2 composite microcapsules, and 2 parts of PCM@SiO2 composite microcapsules were mixed evenly, and then 42 parts of tap water was added and mixed evenly to obtain a rapid heat storage type cement-based heat storage material.
[0086] Example 4
[0087] 1) 60 parts of n-octadecane was added to 120 parts of absolute ethanol and 800 parts of deionized water (the mass ratio of n-octadecane, absolute ethanol and deionized water is 1:2:13.3), heated to 35 °C and stirred at a rate of 500 r / min for 30 min to melt it, then the temperature was lowered to 25 °C to solidify it again, and after filtration, washing and drying, n-octadecane particles were obtained;
[0088] 2) 40 parts of epoxy resin, 4 parts of γ-aminopropyltriethoxysilane, 400 parts of polyvinyl alcohol and 4000 parts of deionized water were mixed (the mass ratio of epoxy resin, γ-aminopropyltriethoxysilane, polyvinyl alcohol and water is 1:0.1:10:100), heated to 98 °C and stirred at a rate of 300 r / min for 6 h to obtain mixture A;
[0089] 3) 7 parts of mixture A, 60 parts of n-octadecane particles and 50 parts of graphite were mixed evenly (the mass ratio of mixture A, n-octadecane particles and graphite is 1:8.57:7.14) to obtain mixture B;
[0090] 4) 48 parts of mixture B and 40 parts of tetraethyl orthosilicate were stirred and mixed evenly at 45 °C (the mass ratio of mixture B to tetraethyl orthosilicate is 1.2:1) to obtain mixture C;
[0091] 5) 1200 parts of deionized water, 9 parts of cetyltrimethylammonium bromide and 600 parts of absolute ethanol were stirred and mixed evenly at room temperature (the mass ratio of deionized water, cetyltrimethylammonium bromide and absolute ethanol is 2:0.015:1) to obtain mixture D;
[0092] 6) Under the condition of a constant temperature water bath at 35 °C, after mixing mixture C and mixture D (the mass ratio of mixture C to mixture D is 1:20.55), first stir at a high speed of 1100 r / min for 5 min, then ultrasonicate at an ultrasonic power of 800 W for 5 min, and then add 12 parts of ammonia water with a mass concentration of 25% (the mass ratio of ammonia water to deionized water in step 5 is 1:100), and stir and react at a rate of 800 r / min for 16 h. After the reaction is completed, take out the mixture, perform suction filtration, washing, and drying to obtain C-PCM@SiO2 composite microcapsules;
[0093] 7) Take 100 parts of cement and 8 parts of C-PCM@SiO2 composite microcapsules and mix them evenly, then add 50 parts of tap water and mix evenly to obtain a rapid heat storage type cement-based heat storage material.
[0094] Comparative Example 4-1
[0095] Take 100 parts of cement and add 50 parts of tap water and mix evenly to obtain a cement-based material.
[0096] Comparative Example 4-2
[0097] Without performing steps 1) to 3), replace 48 parts of mixture B in step 4) with 48 parts of graphite and perform subsequent operations to prepare C@SiO2 composite microcapsules;
[0098] Without performing steps 1) to 3), replace 48 parts of mixture B in step 4) with 48 parts of n-octadecane and perform subsequent operations to prepare PCM@SiO2 composite microcapsules;
[0099] Take 100 parts of cement, 3.64 parts of C@SiO2 composite microcapsules, and 4.36 parts of PCM@SiO2 composite microcapsules and mix them evenly, then add 50 parts of tap water and mix evenly to obtain a rapid heat storage type cement-based heat storage material.
[0100] Example 5
[0101] 1) Add 40 parts of n-eicosane to 150 parts of absolute ethanol and 600 parts of deionized water (the mass ratio of n-eicosane, absolute ethanol, and deionized water is 1:3.75:15), heat to 45 °C and stir at a rate of 300 r / min for 30 min to melt it, then lower the temperature to 30 °C to solidify it again. After filtration, washing, and drying, obtain n-eicosane particles;
[0102] 2) Mix 50 parts of epoxy resin, 5 parts of γ-aminopropyltriethoxysilane, 500 parts of polyvinyl alcohol with 5000 parts of deionized water (the mass ratio of epoxy resin, γ-aminopropyltriethoxysilane, polyvinyl alcohol, and water is 1:0.1:10:100), heat to 93 °C and stir at a rate of 500 r / min for 5 h to obtain mixture A;
[0103] 3) Mix 8 parts of mixture A, 70 parts of n - eicosane particles and 60 parts of graphite evenly (the mass ratio of mixture A, n - eicosane particles and graphite is 1:8.75:7.5) to obtain mixture B;
[0104] 4) Mix 60 parts of mixture B and 50 parts of tetraethyl orthosilicate evenly by stirring at 50 °C (the mass ratio of mixture B to tetraethyl orthosilicate is 1.2:1) to obtain mixed solution C;
[0105] 5) Mix 1200 parts of deionized water, 10 parts of cetyltrimethylammonium bromide and 780 parts of absolute ethanol evenly by stirring at room temperature (the mass ratio of deionized water, cetyltrimethylammonium bromide and absolute ethanol is 1.54:0.012:1) to obtain mixed solution D;
[0106] 6) Under the condition of a constant - temperature water bath at 45 °C, mix mixed solution C and mixed solution D (the mass ratio of mixed solution C to mixed solution D is 1:18). First, stir at a high speed of 1200 r / min for 8 min, then ultrasonicate at an ultrasonic power of 700 W for 10 min. Then add 8 parts of ammonia water with a mass concentration of 25% (the mass ratio of ammonia water to the deionized water in step 5 is 1:150) and stir - react at a speed of 800 r / min for 20 h. After the reaction ends, take out the mixed solution, carry out suction filtration, washing, and drying to obtain C - PCM@SiO2 composite microcapsules;
[0107] 7) Take 100 parts of cement and 6 parts of C - PCM@SiO2 composite microcapsules and mix them evenly, then add 55 parts of tap water and mix evenly to obtain a fast - heat - storage type cement - based heat - storage material.
[0108] Comparative example 5 - 1
[0109] Take 100 parts of cement and add 55 parts of tap water and mix evenly to obtain a cement - based material.
[0110] Comparative example 5 - 2
[0111] Without performing steps 1) to 3), replace 60 parts of mixture B in step 4) with 60 parts of graphite and perform subsequent operations to prepare C@SiO2 composite microcapsules;
[0112] Without performing steps 1) to 3), replace 60 parts of mixture B in step 4) with 60 parts of n - eicosane and perform subsequent operations to prepare PCM@SiO2 composite microcapsules;
[0113] Take 100 parts of cement, 2.77 parts of C@SiO2 composite microcapsules, 3.23 parts of PCM@SiO2 composite microcapsules and mix them evenly, then add 55 parts of tap water and mix evenly to obtain a fast - heat - storage type cement - based heat - storage material.
[0114] Example 6
[0115] 1) Add 50 parts of n-octadecane to 120 parts of absolute ethanol and 1000 parts of deionized water (the mass ratio of n-octadecane, absolute ethanol and deionized water is 1:2.4:20), heat to 40 °C and stir at a rate of 450 r / min for 30 min to melt it, then lower the temperature to 25 °C to solidify it again. After filtration, washing and drying, n-octadecane particles are obtained;
[0116] 2) Mix 40 parts of epoxy resin, 4 parts of γ-aminopropyltriethoxysilane, 400 parts of polyvinyl alcohol and 4000 parts of deionized water (the mass ratio of epoxy resin, γ-aminopropyltriethoxysilane, polyvinyl alcohol and water is 1:0.1:10:100), heat to 96 °C and stir at a rate of 400 r / min for 6 h to obtain mixture A;
[0117] 3) Mix 7 parts of mixture A, 70 parts of n-octadecane particles and 49 parts of graphite evenly (the mass ratio of mixture A, n-octadecane particles and graphite is 1:10:7) to obtain mixture B;
[0118] 4) Mix 45 parts of mixture B and 50 parts of tetraethyl orthosilicate evenly at 30 °C (the mass ratio of mixture B to tetraethyl orthosilicate is 0.9:1) to obtain mixed liquid C;
[0119] 5) Mix 1200 parts of deionized water, 8 parts of cetyltrimethylammonium bromide and 750 parts of absolute ethanol evenly at room temperature (the mass ratio of deionized water, cetyltrimethylammonium bromide and absolute ethanol is 1.6:0.01:1) to obtain mixed liquid D;
[0120] 6) Under the condition of a 40 °C constant temperature water bath, mix mixed liquid C and mixed liquid D (the mass ratio of mixed liquid C to mixed liquid D is 1:20.61). First, stir at a high speed of 1100 r / min for 8 min, then ultrasonicate at an ultrasonic power of 700 W for 10 min, and then add 9 parts of 25% ammonia water by mass (the mass ratio of ammonia water to the deionized water in step 5 is 1:133.3) and stir and react at a rate of 600 r / min for 24 h. After the reaction is completed, take out the mixed liquid, carry out suction filtration, washing and drying to obtain C-PCM@SiO2 composite microcapsules;
[0121] 7) Take 100 parts of cement and 10 parts of C-PCM@SiO2 composite microcapsules and mix them evenly, then add 40 parts of tap water and mix them evenly to obtain a rapid heat storage type cement-based heat storage material.
[0122] Comparative Example 6-1
[0123] Take 100 parts of cement and add 40 parts of tap water, mix them evenly to obtain a cement-based material.
[0124] Comparative Example 6-2
[0125] Do not perform steps 1) to 3), replace 45 parts of mixture B in step 4) with 45 parts of graphite, and perform subsequent operations to prepare C@SiO2 composite microcapsules;
[0126] Do not perform steps 1) to 3), replace 45 parts of mixture B in step 4) with 45 parts of n-octadecane, and perform subsequent operations to prepare PCM@SiO2 composite microcapsules;
[0127] Take 100 parts of cement, 4.12 parts of C@SiO2 composite microcapsules, and 5.88 parts of PCM@SiO2 composite microcapsules, mix them evenly, and then add 50 parts of tap water and mix evenly to obtain a fast heat storage type cement-based heat storage material.
[0128] The performance of the C-PCM@SiO2 composite microcapsules prepared in the above examples is shown in Table 1.
[0129] Table 1
[0130] Experimental group Average particle size (μm) Latent heat of phase change (J / g) Thermal conductivity (W / m·K) Example 1 1.68 70 1.8 Example 2 1.97 75 1.95 Example 3 0.75 64 2.68 Example 4 1.54 83 1.33 Example 5 1.32 80 0.98 Example 6 0.85 105 0.68
[0131] The performance of the fast heat storage type cement-based heat storage materials prepared in the above examples, the cement-based materials prepared in the comparative examples, and the fast heat storage type cement-based heat storage materials is shown in Table 2.
[0132] Table 2
[0133]
[0134]
[0135] As can be seen from Table 2, after introducing C-PCM@SiO2 composite microcapsules into the cement matrix in the embodiments of the present invention, not only is there no adverse effect on the fluidity and late compressive strength, but on the contrary, the early strength is improved, and the thermal conductivity and phase change latent heat of the material are also increased. Moreover, the phase change latent heat loss after 150 phase change cycles is ≤2.5%, showing reliable rapid heat storage performance and temperature change resistance. In Comparative Examples 1-3, graphite was directly added, significantly reducing the fluidity and compressive strength of the material, and the phase change latent heat loss also increased significantly. The comparative examples of preparing cement-based heat storage materials by separately coating graphite and paraffin-based phase change materials show that the thermal conductivity of the separately coated cement-based phase change materials decreases significantly, and the phase change latent heat loss also increases significantly. This is because: in the system coated simultaneously in the embodiments, graphite and paraffin coexist in the same shell layer, and the high thermal conductivity of graphite can promote the uniform distribution of heat, reducing the degradation of the phase change material caused by local overheating; while in the comparative examples, when graphite is separately coated, the silica shell layer is more uniform, dense and complete, weakening its thermal conductivity. After the paraffin-based phase change material is separately coated, its hydrophobicity may lead to poor dispersibility in the cement matrix, further hindering the uniform distribution of graphite particles and indirectly weakening the thermal conductivity. After being separately coated, the functions of the two are separated, and graphite cannot assist paraffin in dissipating heat, exacerbating thermal runaway and latent heat loss.
[0136] The above embodiments are merely examples clearly described and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here, and the obvious changes or modifications thus extended are still within the protection scope of the present invention.
Claims
1. A fast heat storage type cement-based heat storage material, characterized in that, It comprises raw materials in the following parts by mass: 100 parts of cement, 2 - 10 parts of C-PCM@SiO2 composite microcapsules, and 40 - 60 parts of water; the C-PCM@SiO2 composite microcapsules have amorphous silica as the capsule wall and encapsulate a core material composed of graphite and a paraffin-based phase change material.
2. The fast heat storage type cement-based heat storage material according to claim 1, characterized in that, The average particle size of the C-PCM@SiO2 composite microcapsules is 0.5 - 2 μm, the thermal conductivity is 0.5 - 3 W / mK, and the phase change latent heat is 60 - 110 J / g; the paraffin-based phase change material is one of n-hexadecane, n-octadecane, n-eicosane, and n-docosane; the particle size of the graphite is ≤1 μm; the cement is ordinary Portland cement.
3. The fast heat storage type cement-based heat storage material according to claim 1, characterized in that, The fluidity of the fast heat storage type cement-based heat storage material is ≥190 mm, the thermal conductivity is 0.91 - 1.61 W / m·K, the 3d compressive strength is 20 - 35 MPa, the 28d compressive strength is 40 - 55 MPa, and the phase change latent heat loss after 150 phase change cycles is ≤2.5%.
4. The fast heat storage type cement-based heat storage material according to claim 1, characterized in that, The preparation method of the C-PCM@SiO2 composite microcapsules comprises the following steps: 1) Add the paraffin-based phase change material into absolute ethanol and water, heat and stir to melt and disperse it, then lower the temperature and solidify it again to obtain paraffin-based phase change material particles. 2) Mix epoxy resin, γ-aminopropyltriethoxysilane, polyvinyl alcohol, and water, and heat and stir to obtain mixture A. 3) Mix mixture A, paraffin-based phase change material particles, and graphite evenly to obtain mixture B. 4) Mix mixture B and tetraethyl orthosilicate evenly to obtain mixed liquid C. 5) Mix water, cetyltrimethylammonium bromide, and absolute ethanol evenly to obtain mixed liquid D. 6) Mix mixed liquid C and mixed liquid D, first stir at high speed and then perform ultrasonic treatment, and then add ammonia water and stir to react to obtain C-PCM@SiO2 composite microcapsules.
5. The fast heat storage type cement-based heat storage material according to claim 4, characterized in that, In step 1), the mass ratio of the paraffin-based phase change material, absolute ethanol, and water is 1:(2 - 5):(10 - 20), the heating and stirring temperature is 5 - 10 °C higher than the melting point temperature of the paraffin-based phase change material, the stirring speed is 300 - 500 r / min, the stirring time is 30 - 35 min, and then the temperature is lowered to 5 - 10 °C lower than the melting point temperature of the paraffin-based phase change material and solidified again.
6. The rapid heat storage type cement-based heat storage material according to claim 4, characterized in that The epoxy equivalent of the epoxy resin is 210 - 250 g / eq; in step 2), the mass ratio of the epoxy resin, γ-aminopropyltriethoxysilane, polyvinyl alcohol, and water is 1:(0.1 - 0.15):(10 - 12):(100 - 110), the heating and stirring temperature is 93 - 98 °C, the stirring speed is 300 - 500 r / min, and the stirring time is 4 - 6 h.
7. The fast heat storage type cement-based heat storage material according to claim 4, wherein In step 3), the mass ratio of mixture A, paraffin-based phase change material particles, and graphite is 1:(8 - 12):(7 - 10); in step 4), the mass ratio of mixture B and tetraethyl orthosilicate is (0.8 - 1.2):1, and the temperature is controlled at 20 - 60 °C during mixing.
8. The fast heat storage type cement-based heat storage material according to claim 4, characterized in that, In step 5), the mass ratio of the water, cetyltrimethylammonium bromide and absolute ethanol is (1.5 - 2):(0.01 - 0.015):1; in step 6), the mass ratio of the mixed solution C to the mixed solution D is 1:(17 - 25).
9. The fast heat storage type cement-based heat storage material according to claim 4, characterized in that, In step 6), the temperature is controlled to be 5 - 10 °C higher than the melting point temperature of the paraffin-based phase change material; the speed of the high-speed stirring is 800 - 1500 r / min, and the time is 5 - 10 min; the power of the ultrasonic treatment is 600 - 800 W, and the time is 5 - 15 min; the mass concentration of the ammonia water is 25 - 28%, and the mass ratio of the ammonia water to the water in step 5) is 1:(100 - 150); the stirring speed of the stirring reaction is 500 - 800 r / min, and the reaction time is 16 - 24 h.
10. A preparation method of the fast heat storage type cement-based heat storage material according to any one of claims 1 to 9, characterized in that, It includes the following steps: First, mix the cement and the C-PCM@SiO2 composite microcapsules evenly, and then add water and mix evenly to obtain the rapid heat storage type cement-based heat storage material.