CN114656939B - Expanded graphite-based composite phase change material with anisotropic thermal conductivity and preparation method thereof - Google Patents
Expanded graphite-based composite phase change material with anisotropic thermal conductivity and preparation method thereof Download PDFInfo
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Abstract
The invention provides an expanded graphite-based composite phase change material with anisotropic heat conductivity and a preparation method thereof, and belongs to the technical field of composite phase change material heat storage. According to the invention, by compounding the mass percentages of different phase change materials and regulating and controlling the compaction density, the expanded graphite with different mass fractions and the phase change materials are compounded and the thermal conductivity of the composite phase change material block prepared by molding with different compaction densities is strengthened in the axial direction and the radial direction, and the degree of strengthening of the thermal conductivity in the two directions is different (the degree of strengthening of the radial thermal conductivity is higher than that of the axial thermal conductivity at the same time), so that the anisotropy of the thermal conductivity is displayed, and a foundation is laid for the subsequent regulation and control research of the anisotropy of the thermal conductivity of the composite phase change materials. The invention can also strengthen the heat conductivity of the composite phase change material block in the axial direction and the radial direction by adding different graphite film contents into the inorganic hydrated salt-expanded graphite-based composite phase change material.
Description
Technical Field
The invention relates to the technical field of composite phase change material heat storage, in particular to an expanded graphite-based composite phase change material with anisotropic heat conductivity and a preparation method thereof.
Background
The phase change material stores and releases heat energy through phase change, and the temperature is basically kept unchanged in the phase change process, so that the phase change material is a material with both temperature and energy storage, and is widely applied to the fields of building energy conservation, lithium ion battery thermal management, electronic device cooling, waste heat and waste heat recovery, solar heat utilization and the like. In the phase transition of the phase change material, solid-liquid phase transition is most common, however, liquid leakage is easy to occur when the phase change material undergoes solid-liquid phase transition, so that the shape stability of the phase change material can be maintained through the adsorption of the porous matrix. Phase change materials, on the other hand, generally suffer from low thermal conductivity, which affects the rate of storage and release of thermal energy. The expanded graphite is used as a porous adsorption matrix, and the expanded graphite and the phase-change material are compounded, so that the problem of liquid leakage of the phase-change material can be solved, and the heat conductivity of the phase-change material can be improved. However, the thermal conductivity achieved by the current compact-formed expanded graphite-based composite phase change material is only that of a single direction, i.e., that of a direction parallel to the bulk pressure (axial direction), and anisotropy of thermal energy transfer cannot be achieved.
Disclosure of Invention
The invention aims to provide an expanded graphite-based composite phase-change material with anisotropic thermal conductivity and a preparation method thereof, wherein the method can realize anisotropic reinforcement of the thermal conductivity of the composite phase-change material.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of an expanded graphite-based composite phase-change material with anisotropic thermal conductivity, which comprises the following steps:
mixing a phase change material with expanded graphite, and heating and melting to obtain a molten mixture;
pressing and forming the molten mixture to obtain an expanded graphite-based composite phase change material;
the mass of the expanded graphite accounts for 10-30% of the total mass of the phase change material and the expanded graphite; the phase change material is an organic phase change material or an inorganic hydrated salt phase change material;
when the phase change material is an organic phase change material, the compaction density of the expanded graphite based composite phase change material is 600-1000 kg/m 3 ；
When the phase change material is an inorganic hydrated salt phase change material, the compaction density of the expanded graphite-based composite phase change material is 600-1700 kg/m 3 。
Preferably, when the phase change material is an inorganic hydrated salt phase change material, the method further comprises mixing a graphite film with the molten mixture before compression molding, wherein the mass ratio of the graphite film to the expanded graphite is (0-1): 1.
preferably, the graphite film has a length, width and thickness of 30mm, 10mm and 0.05mm, respectively.
Preferably, the organic phase change material is paraffin.
Preferably, the inorganic hydrated salt phase change material is magnesium nitrate hexahydrate, magnesium chloride hexahydrate or sodium acetate trihydrate.
Preferably, when the phase change material is an organic phase change material, the temperature of the heating and melting is 80 ℃.
Preferably, when the phase change material is an inorganic hydrated salt phase change material, the temperature of the heating and melting is 110 ℃.
Preferably, when the phase change material is an organic phase change material, the compacted density of the expanded graphite based composite phase change material is 600kg/m 3 、700kg/m 3 、800kg/m 3 、900kg/m 3 Or 1000kg/m 3 。
Preferably, when the phase change material is an inorganic hydrated salt phase change material, the compact density of the expanded graphite based composite phase change material is 600kg/m 3 、700kg/m 3 、800kg/m 3 、900kg/m 3 、1000kg/m 3 、1100kg/m 3 、1200kg/m 3 、1300kg/m 3 、1400kg/m 3 、1500kg/m 3 、1600kg/m 3 Or 1700kg/m 3 。
The invention provides the expanded graphite-based composite phase change material prepared by the preparation method, which has anisotropic thermal conductivity.
According to the preparation method, by compounding the mass percentages and the compaction densities of different phase change materials, the thermal conductivity of a composite phase change material block prepared by compounding the expanded graphite with different mass percentages and compacting the phase change materials with different compaction densities is strengthened simultaneously in the axial direction (parallel to the block pressure direction) and the radial direction (perpendicular to the block pressure direction), the mass percentages and the compaction densities of the randomly distributed scaly expanded graphite tend to be arranged continuously in the radial direction under the action of pressure to form more continuous and compact heat conducting networks, the number of the vertically arranged expanded graphite-based composite phase change materials in the axial direction is smaller than the number of the horizontally arranged heat conducting channels in the radial direction, the heat conducting channels in the axial direction are loose and broken under the action of pressure, and the interface thermal resistance is large.
The expanded graphite used in the invention has high heat conductivity, is loose and porous, can prevent the phase change material from leaking under the action of capillary force of the pore canal and surface tension between the sheets, and simultaneously forms a continuous high heat conductivity network structure which is arranged in an oriented way under the action of pressure when the block is formed, thereby being beneficial to heat energy conduction, leading to more obvious heat conductivity improvement in the radial direction, leading to the heat conductivity in the radial direction being obviously higher than the heat conductivity in the axial direction, having high anisotropism (the ratio of the radial heat conductivity to the axial heat conductivity), showing anisotropism in the aspect of heat energy transmission and having important exploration value for regulating and controlling the heat energy conduction rate.
In addition, the method for adding different graphite film contents into the inorganic hydrated salt-expanded graphite-based composite phase-change material can strengthen the heat conductivity of the composite phase-change material block in the axial direction and the radial direction, so that the degree of anisotropy of the heat conductivity is improved, and the heat conductivity of the whole phase-change material is improved due to the fact that the graphite film forms a continuous high heat conduction network structure under the action of pressure during block molding.
Drawings
FIG. 1 is a bar graph of axial and radial thermal conductivity as a function of bulk compacted density for OP44E paraffin wax/expanded graphite composite phase change materials of 10%, 20% and 30% mass fraction expanded graphite;
FIG. 2 is a bar graph of the degree of anisotropy of thermal conductivity of OP44E paraffin wax/expanded graphite composite phase change materials of 10%, 20% and 30% mass fraction expanded graphite as a function of bulk compacted density;
FIG. 3 is a bar graph of axial and radial thermal conductivities of magnesium nitrate hexahydrate/expanded graphite composite phase change materials of 10%, 20%, and 30% mass fraction expanded graphite as a function of bulk compacted density;
FIG. 4 is a bar graph of thermal conductivity anisotropy of magnesium nitrate hexahydrate/expanded graphite composite phase change materials of 10%, 20% and 30% mass fraction expanded graphite as a function of bulk compacted density;
FIG. 5 is a bar graph of axial and radial thermal conductivity of a magnesium nitrate hexahydrate/expanded graphite composite phase change material of 20 mass fraction expanded graphite as a function of bulk compacted density;
FIG. 6 is a bar graph of thermal conductivity anisotropy of a magnesium nitrate hexahydrate/expanded graphite composite phase change material of 20 mass fraction expanded graphite as a function of bulk compacted density;
FIG. 7 is a bar graph of axial and radial thermal conductivity of 20% mass fraction expanded graphite magnesium nitrate hexahydrate/expanded graphite-graphite film composite phase change material as a function of graphite film addition amount, with the compacted density of the magnesium nitrate hexahydrate/expanded graphite composite phase change material unchanged;
fig. 8 is a bar graph of the degree of anisotropy of thermal conductivity of 20% mass fraction expanded graphite magnesium nitrate hexahydrate/expanded graphite-graphite film composite phase change material as a function of the amount of added graphite film when the compacted density of the magnesium nitrate hexahydrate/expanded graphite composite phase change material is unchanged.
Detailed Description
The invention provides a preparation method of an expanded graphite-based composite phase-change material with anisotropic thermal conductivity, which comprises the following steps:
mixing a phase change material with expanded graphite, and heating and melting to obtain a molten mixture;
pressing and forming the molten mixture to obtain an expanded graphite-based composite phase change material;
the mass of the expanded graphite accounts for 10-30% of the total mass of the phase change material and the expanded graphite; the phase change material is an organic phase change material or an inorganic hydrated salt phase change material;
when the phase change material is an organic phase change material, the compaction density of the expanded graphite based composite phase change material is 600-1000 kg/m 3 ；
When the phase change material is an inorganic hydrated salt phase change material, the compaction density of the expanded graphite-based composite phase change material is 600-1700 kg/m 3 。
In the present invention, the required raw materials or reagents are commercially available products well known to those skilled in the art unless specified otherwise.
The phase change material is mixed with the expanded graphite and heated and melted to obtain a melted mixture. In the invention, the phase change material is an organic phase change material or an inorganic hydrated salt phase change material; the organic phase change material is preferably paraffin; the paraffin is preferably RT28, OP44E or n-eicosane.
In the present invention, the inorganic hydrated salt phase change material is preferably magnesium nitrate hexahydrate, magnesium chloride hexahydrate or sodium acetate trihydrate.
In the present invention, the mass of the expanded graphite is 10 to 30% of the total mass of the phase change material and the expanded graphite, preferably 20%.
The process of mixing the phase change material and the expanded graphite is not particularly limited, and the materials are uniformly mixed according to the process well known in the art.
In the present invention, when the phase change material is an organic phase change material, the temperature of the heating and melting is preferably 80 ℃; when the phase change material is an inorganic hydrated salt phase change material, the temperature of the heating and melting is preferably 110 ℃. In the present invention, the heating and melting are preferably performed in an oven.
After obtaining a molten mixture, the invention carries out compression molding on the molten mixture to obtain the expanded graphite-based composite phase change material. In the invention, when the phase change material is an organic phase change material, the compaction density of the expanded graphite based composite phase change material is 600-1000 kg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the More preferably 600kg/m 3 、700kg/m 3 、800kg/m 3 、900kg/m 3 Or 1000kg/m 3 . When the phase change material is an inorganic hydrated salt phase change material, the compaction density of the expanded graphite-based composite phase change material is 600-1700 kg/m 3 More preferably 600kg/m 3 、700kg/m 3 、800kg/m 3 、900kg/m 3 、1000kg/m 3 、1100kg/m 3 、1200kg/m 3 、1300kg/m 3 、1400kg/m 3 、1500kg/m 3 、1600kg/m 3 Or 1700kg/m 3 。
The present invention preferably uses a tablet press to perform the compression molding; the specific process of the press molding is not particularly limited in the present invention, and the above-mentioned compacted density expanded graphite based composite phase change material may be obtained according to a process well known in the art.
The size of the expanded graphite matrix composite phase change material obtained by compression molding is not particularly limited, and the material can be adjusted according to actual requirements; in an embodiment of the invention, square blocks with dimensions 40mm x 40mm are compression molded.
As another aspect of the present invention, when the phase change material is an inorganic hydrous salt phase change material, the press molding is preferably further comprised of mixing a graphite film with a molten mixture, the mass ratio of the graphite film to the expanded graphite being (0 to 1): 1, preferably (0.2 to 0.8): 1, more preferably (0.4 to 0.6): 1.
in the present invention, the length, width and thickness of the graphite film are preferably 30mm, 10mm and 0.05mm, respectively.
The process of mixing the graphite film with the molten mixture is not particularly limited in the present invention, and the materials may be uniformly mixed according to a process well known in the art.
The invention provides the expanded graphite-based composite phase change material prepared by the preparation method, which has anisotropic thermal conductivity.
The technical solutions of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The OP44E paraffin/expanded graphite composite phase change material of the embodiment is prepared from the following raw materials in parts by weight: 70 parts of OP44E paraffin and 30 parts of expanded graphite; 80 parts of OP44E paraffin and 20 parts of expanded graphite; 90 parts of OP44E paraffin wax and 10 parts of expanded graphite.
Uniformly mixing OP44E paraffin wax and expanded graphite according to mass ratios of 7:3,8:2 and 9:1 respectively, and heating at a constant temperature of 80 ℃ in an oven to obtain a molten mixture;
according to 600kg/m respectively 3 、700kg/m 3 、800kg/m 3 、900kg/m 3 And 1000kg/m 3 The molten mixture is pressed into square blocks with the size of 40mm multiplied by 40mm, and the OP44E paraffin/expanded graphite composite phase change material is obtained.
Example 2
The magnesium nitrate hexahydrate/expanded graphite composite phase change material of the embodiment is prepared from the following raw materials in parts by weight: 70 parts of magnesium nitrate hexahydrate and 30 parts of expanded graphite; 80 parts of magnesium nitrate hexahydrate and 20 parts of expanded graphite; 90 parts of magnesium nitrate hexahydrate and 10 parts of expanded graphite.
Uniformly mixing magnesium nitrate hexahydrate and expanded graphite according to mass ratios of 7:3,8:2 and 9:1 respectively, and heating at a constant temperature of 110 ℃ in an oven to obtain a molten mixture;
according to 600kg/m respectively 3 、700kg/m 3 、800kg/m 3 And 900kg/m 3 The molten mixture is pressed into square blocks with the size of 40mm multiplied by 40mm, and the magnesium nitrate hexahydrate/expanded graphite composite phase change material is obtained.
Example 3
The magnesium nitrate hexahydrate/expanded graphite composite phase change material of the embodiment is prepared from the following raw materials in parts by weight: 80 parts of magnesium nitrate hexahydrate and 20 parts of expanded graphite.
Uniformly mixing magnesium nitrate hexahydrate and expanded graphite according to a mass ratio of 8:2, and heating at a constant temperature of 110 ℃ in an oven to obtain a molten mixture;
according to 1000kg/m respectively 3 、1100kg/m 3 、1200kg/m 3 、1300kg/m 3 、1400kg/m 3 、1500kg/m 3 、1600kg/m 3 And 1700kg/m 3 The molten mixture was pressed into square blocks of 40mm by 40mm in size to obtain a magnesium nitrate hexahydrate/expanded graphite composite phase change material.
Example 4
The magnesium nitrate hexahydrate/expanded graphite-graphite film composite phase-change material is prepared from the following raw materials in parts by weight: 80 parts of magnesium nitrate hexahydrate, 20 parts of expanded graphite, and the weight parts of the graphite film and the expanded graphite are respectively 0:1, 0.2:1, 0.4:1, 0.6:1, 0.8:1 and 1.0:1.
Uniformly mixing magnesium nitrate hexahydrate and expanded graphite according to a mass ratio of 8:2, and heating at a constant temperature of 110 ℃ in an oven to obtain a molten mixture;
adding a graphite film into the molten mixture, stirring uniformly, wherein the shape of the graphite film is kept to be 30mm, 10mm and 0.05mm in length, width and thickness, and the compacted density of the magnesium nitrate hexahydrate/expanded graphite molten composite material is 1600kg/m 3 And pressing the obtained mixture into square blocks with the size of 40mm multiplied by 40mm to obtain the magnesium nitrate hexahydrate/expanded graphite-graphite film composite phase change material.
Performance testing
The square blocks prepared in examples 1 to 4 were tested for thermal conductivity using a HotDiskTPS2200 thermal constant analyzer; when the tablet press is used for compression molding, the thermal conductivity coefficient of the upper surface and the lower surface of the square block is defined to be parallel to the pressure direction as an axial direction, and the thermal conductivity coefficient of the four surfaces of the side surface of the square block is defined to be perpendicular to the pressure direction as a radial direction.
1) The test results of the axial and radial thermal conductivity and the anisotropism degree of the OP44E paraffin/expanded graphite composite phase-change material prepared in the example 1 are shown in figures 1-2.
As shown in fig. 1 and 2, under the same compaction density condition, as the mass fraction of the Expanded Graphite (EG) increases, the axial and radial thermal conductivities of the OP44E paraffin/expanded graphite composite phase change material block increase simultaneously, and the thermal conductivity anisotropy, which is characterized by the anisotropy (the anisotropy is the ratio of the radial thermal conductivity to the axial thermal conductivity), also increases gradually. Specifically, the compaction densities were each 600kg/m 3 、700kg/m 3 、800kg/m 3 、900kg/m 3 And 1000kg/m 3 When the mass fraction of the expanded graphite is increased from 10% to 30%, the axial thermal conductivity of the OP44E paraffin/expanded graphite composite phase change material block is changed into: 2.9 to 7.4W/(m.K), 4.1 to 8.5W/(m.K), 5.1 to 9.8W/(m.K), 6.3 to 10.9W/(m.K) and 6.6 to 10.8W/(m.K); the OP44E paraffin/expanded graphite composite phase change material block radial thermal conductivity vs. strain is: 3.1 to 10.3W/(m.K), 4.3 to 13.1W/(m.K), 5.5 to 14.8W/(m.K), 7.0 to 17.7W/(mK) and 7.7-18.8W/(mK); the anisotropy of the OP44E paraffin/expanded graphite composite phase-change material block is correspondingly changed as follows: 1.04 to 1.39,1.07 to 1.54,1.09 to 1.51,1.12 to 1.61,1.16 to 1.74.
As shown in fig. 1 and fig. 2, under the condition that the mass fraction of the expanded graphite is the same, as the compaction density is increased, the axial and radial thermal conductivities of the OP44E paraffin/expanded graphite composite phase change material block are increased at the same time, and the anisotropism degree is also gradually improved. Specifically, the compacted density was from 600kg/m at 10%, 20% and 30% by mass of the expanded graphite, respectively 3 Up to 1000kg/m 3 The OP44E paraffin/expanded graphite composite phase change material block axial thermal conductivity vs. strain is: 2.9 to 6.6W/(mK), 5.8 to 9.6W/(mK) and 7.4 to 10.8W/(mK); the OP44E paraffin/expanded graphite composite phase change material block radial thermal conductivity vs. strain is: 3.1 to 7.7W/(mK), 6.4 to 14.5W/(mK) and 10.3 to 18.8W/(mK); the anisotropy of the OP44E paraffin/expanded graphite composite phase-change material block is correspondingly changed as follows: 1.04 to 1.16, 1.11 to 1.50 and 1.39 to 1.74.
2) The test results of the axial and radial thermal conductivities and the anisotropies of the magnesium nitrate hexahydrate/expanded graphite composite phase-change material prepared in example 2 are shown in fig. 3 to 4.
As shown in fig. 3 and fig. 4, under the same compaction density condition, as the mass fraction of the expanded graphite increases, the axial and radial thermal conductivities of the magnesium nitrate hexahydrate/expanded graphite composite phase change material block also increase, and the anisotropism degree also increases gradually. Specifically, the compaction densities were each 600kg/m 3 、700kg/m 3 、800kg/m 3 And 900kg/m 3 When the mass fraction of the expanded graphite is increased from 10% to 30%, the axial thermal conductivity of the magnesium nitrate hexahydrate/expanded graphite composite phase change material block is changed into: 1.1 to 5.7W/(m.K), 1.5 to 7.0W/(m.K), 1.7 to 7.9W/(m.K) and 2.0 to 8.9W/(m.K); the radial thermal conductivity of the magnesium nitrate hexahydrate/expanded graphite composite phase change material block is changed into: 1.2 to 7.7W/(m.K), 1.6 to 9.1W/(m.K), 1.9 to 10.8W/(m.K) and 2.2 to 13.0W/(m.K); the anisotropism degree of the hexahydrated magnesium nitrate/expanded graphite composite phase change material block is correspondingly changed as follows: 1.11 to 1.35, 107-1.30, 1.10-1.37 and 1.11-1.46.
As shown in fig. 3 and 4, under the condition that the mass fraction of the expanded graphite is the same, as the compaction density is increased, the axial and radial thermal conductivities of the magnesium nitrate hexahydrate/expanded graphite composite phase-change material block are increased at the same time, and the anisotropism degree is also gradually improved. Specifically, the compacted density was from 600kg/m at 10%, 20% and 30% by mass of the expanded graphite, respectively 3 Up to 900kg/m 3 The axial thermal conductivity of the magnesium nitrate hexahydrate/expanded graphite composite phase change material block is relatively changed into: 1.1 to 2.0W/(mK), 2.7 to 5.2W/(mK) and 5.7 to 8.9W/(mK); the radial thermal conductivity of the magnesium nitrate hexahydrate/expanded graphite composite phase change material block is changed into: 1.2 to 2.2W/(mK), 3.3 to 6.4W/(mK) and 7.7 to 13.0W/(mK); the anisotropism degree of the hexahydrated magnesium nitrate/expanded graphite composite phase change material block is correspondingly changed as follows: 1.07 to 1.11, 1.22 to 1.23 and 1.35 to 1.46.
3) The test results of the axial and radial thermal conductivities and the anisotropies of the magnesium nitrate hexahydrate/expanded graphite composite phase change material prepared in example 3 are shown in fig. 5 to 6.
As shown in fig. 5 and 6, under the condition that the mass fraction of the expanded graphite is the same, as the compaction density is increased, the axial and radial thermal conductivities of the magnesium nitrate hexahydrate/expanded graphite composite phase-change material block are increased at the same time, and the anisotropism degree is also gradually improved. Specifically, at an expanded graphite mass fraction of 20%, the compacted density was from 1000kg/m 3 Up to 1700kg/m 3 The axial thermal conductivity of the magnesium nitrate hexahydrate/expanded graphite composite phase-change material block is increased from 9.1W/(m.K) to 13.2W/(m.K), the radial thermal conductivity is increased from 10.7W/(m.K) to 20.1W/(m.K), and the anisotropy degree is increased from 1.17 to 1.53.
4) The test results of the axial and radial thermal conductivities and anisotropies of the magnesium nitrate hexahydrate/expanded graphite-graphite film composite phase-change material prepared in example 4 are shown in fig. 7 to 8.
As shown in fig. 7 and 8, under the condition that the mass fraction of the expanded graphite is the same, the compaction density of the magnesium nitrate hexahydrate/expanded graphite composite phase change material is kept unchanged, and the shape of the graphite film keeps length, width and thicknessThe axial and radial heat conductivities of the magnesium nitrate hexahydrate/expanded graphite-graphite film composite phase change material blocks are respectively 30mm, 10mm and 0.05mm unchanged, and the anisotropism degree is gradually improved. Specifically, the compacted density of the magnesium nitrate hexahydrate/expanded graphite fused composite material is 1600kg/m when the mass fraction of the expanded graphite is 20 percent 3 When the weight ratio of the graphite film to the expanded graphite is increased from 0 to 1.0, the axial thermal conductivity of the magnesium nitrate hexahydrate/expanded graphite-graphite film composite phase-change material block is increased from 12.6W/(m.K) to 24.4W/(m.K), the radial thermal conductivity is increased from 18.9W/(m.K) to 40.7W/(m.K), and the anisotropy degree is increased from 1.50 to 1.67.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (4)
1. A preparation method of an expanded graphite-based composite phase change material with anisotropic thermal conductivity comprises the following steps:
mixing a phase change material with expanded graphite, and heating and melting to obtain a molten mixture;
pressing and forming the molten mixture to obtain an expanded graphite-based composite phase change material;
the method also comprises the steps of mixing a graphite film with the molten mixture before compression molding, wherein the mass ratio of the graphite film to the expanded graphite is (0-1): 1;
the mass of the expanded graphite accounts for 20-30% of the total mass of the phase change material and the expanded graphite; the phase change material is magnesium nitrate hexahydrate, and the compaction density of the expanded graphite-based composite phase change material is 600-1700 kg/m 3 ；
The temperature of the heating and melting is 110 ℃.
2. The method of claim 1, wherein the graphite film has a length, width and thickness of 30mm, 10mm and 0.05mm, respectively.
3. The method of claim 1, wherein the compacted density of the expanded graphite based composite phase change material is 600kg/m 3 、700kg/m 3 、800kg/m 3 、900kg/m 3 、1000kg/m 3 、1100kg/m 3 、1200kg/m 3 、1300kg/m 3 、1400kg/m 3 、1500kg/m 3 、1600kg/m 3 Or 1700kg/m 3 。
4. The expanded graphite-based composite phase change material prepared by the preparation method according to any one of claims 1 to 3, which is characterized by having anisotropic thermal conductivity.
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| CN109181649A (en) * | 2018-07-17 | 2019-01-11 | 华南理工大学 | High thermal conductivity optical and thermal conversion composite phase-change heat-storage material and preparation method thereof for solar water heater |
| CN112574718B (en) * | 2019-09-30 | 2022-03-15 | 黄冈师范学院 | Hydrated salt/modified expanded graphite shaped phase-change heat storage material for medium and low temperature and preparation method thereof |
| CN111826127A (en) * | 2020-06-22 | 2020-10-27 | 南京理工大学 | Preparation method of paraffin graphite flake and expanded graphite composite phase change material |
| CN112920779A (en) * | 2021-02-07 | 2021-06-08 | 安徽中烟工业有限责任公司 | Composite phase change material with high phase change latent heat and high thermal conductivity and preparation method thereof |
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