Foamy copper-based phase change energy storage composite material as well as preparation method and application thereof

Abstract

The invention provides a foamy copper-based phase change energy storage composite material as well as a preparation method and application thereof. The composite material is prepared from the following raw materials by mass: 30-50 g of foamy copper, 15-30 g of a modifier, 20-50 g of paraffin, 1-10 g of a thickener and 1-5 g of an adhesive, wherein the adhesive is modified polyvinyl alcohol. According to the preparation method, foamy copper is used as a porous heat conductor, paraffin is used as a phase change material, a graphene substance is used as a modifier, copper nanomaterial modified polyvinyl alcohol is used as an adhesive, and a thickening agent is combined, so that the obtained material has excellent heat-conducting property. And the composite material has good cycle stability, is small in phase change latent heat loss after multiple heat charging and discharging cycles, can be stably applied to the field of solar heat management for a long time, effectively adjusts the temperature, improves the utilization efficiency of solar energy, reduces energy consumption, and has remarkable economic benefits and environmental benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage materials, and in particular to a foam copper-based phase-change energy storage composite material and a preparation method and application thereof. Background Art

[0002] As a clean and renewable energy source, the utilization of solar energy has attracted widespread attention. In solar energy utilization systems, thermal management is of vital importance. Phase change energy storage materials can absorb or release large amounts of heat through phase change when the temperature changes, which can effectively realize the storage and release of energy and is of great significance to solar thermal management. However, traditional phase change energy storage materials have the problem of low thermal conductivity, which leads to slow heat transfer during the charging and discharging process, and low energy storage and release efficiency. At the same time, traditional phase change energy storage materials have poor stability. After undergoing multiple phase change cycles, their phase change temperature will fluctuate significantly, affecting the accuracy of energy storage and release. Moreover, some phase change energy storage materials also have the problem of short service life. Frequent phase change processes can easily damage their internal structure, shortening the effective service life of the material and increasing the cost of use. These have greatly limited its further application and promotion in the field of solar thermal management.

[0003] Copper foam, with its three-dimensional, porous structure, high porosity, large specific surface area, and high thermal conductivity, is an ideal choice for composites with phase-change materials. Composites of copper foam and phase-change materials are expected to fully utilize the foam's high thermal conductivity, accelerating heat transfer through the phase-change material. Simultaneously, its unique structure enhances the stability of the phase-change material, significantly improving its overall performance.

[0004] Patent publication number CN108084971A discloses a composite phase-change material based on copper foam, its preparation method, and a thermal storage pack. The material comprises alternating layers of copper foam metal and graphene, along with a phase-change material, which helps reduce paraffin wax leakage. However, the patent does not address the interactions between the various components of the material, nor does it address improvements in thermal conductivity, stability, and service life.

[0005] Therefore, developing a foam copper-based phase change energy storage composite material with high thermal conductivity, high stability and long service life is an urgent problem to be solved. Summary of the Invention

[0006] The purpose of the present invention is to provide a foam copper-based phase change energy storage composite material, which uses foam copper as a porous thermal conductor, paraffin as a phase change material, a graphene-like substance as a modifier, modified polyvinyl alcohol as an adhesive, and a thickener to prepare a foam copper-based phase change energy storage composite material with high thermal conductivity, high stability and long service life.

[0007] The invention provides a foam copper-based phase-change energy storage composite material. The raw materials for preparing the composite material comprise the following components by mass: 30-50g of foam copper, 15-30g of a modifier, 20-50g of paraffin wax, 1-10g of a thickener and 1-5g of an adhesive, wherein the adhesive is modified polyvinyl alcohol.

[0008] As a further improvement, the raw materials for preparing the modified polyvinyl alcohol include copper nanomaterials and polyvinyl alcohol, and the mass ratio of the copper nanomaterials to the polyvinyl alcohol is (0.2-1.5):1.

[0009] As a further improvement, the preparation method of the modified polyvinyl alcohol comprises the following steps: S3-1: Dissolve copper salt in deionized water, add an additive, stir evenly, transfer to an autoclave, react at 180-280°C for 12-48 hours, and then post-treat to obtain copper nanomaterials; S3-2: Dissolve polyvinyl alcohol in deionized water, heat to 80-95°C, and stir to completely dissolve it to form a polyvinyl alcohol solution. Add copper nanomaterials to the polyvinyl alcohol solution, ultrasonically disperse it for 1-2 hours, then transfer it to a polytetrafluoroethylene mold, put it in the refrigerator and freeze it for 12-18 hours. After thawing, put it back into the refrigerator. Repeat this cycle 2-5 times to obtain modified polyvinyl alcohol.

[0010] As a further improvement, the copper salt in step S3-1 includes one or more of copper sulfate, copper chloride and copper acetate, and the auxiliary agent includes but is not limited to one or more of sodium bicarbonate, sodium hydroxide and sodium borohydride.

[0011] As a further improvement, the modifier comprises one or more of graphene, graphene oxide, and hydroxylated graphene.

[0012] As a further improvement, the thickener comprises one or more of polyurethane, organic bentonite and polyacrylic acid.

[0013] As a further improvement, the pore size of the foam copper is 300-500 μm.

[0014] As a further improvement, the preparation method of the foamed copper comprises the following steps: uniformly mixing copper powder and sodium chloride, adding water to form a mixture, and then pressing to form a blank and drying it; sintering the dried blank in a nitrogen atmosphere, heating it to 650-800°C at a heating rate of 5-10°C / min, and maintaining it for 1-3 hours to obtain a sintered blank; soaking the sintered blank in running water for 30-60 minutes, and after soaking, removing the water therein by centrifugation, and then drying it to obtain the foamed copper.

[0015] On the other hand, the present invention also provides a method for preparing a foam copper-based phase change energy storage composite material, comprising the following steps: heating the paraffin wax to completely dissolve it, adding a thickener, and mixing them evenly to obtain modified paraffin wax; and then compounding the modified paraffin wax, modifier, and adhesive with foam copper by vacuum impregnation to obtain the foam copper-based phase change energy storage composite material.

[0016] On the other hand, the present invention also provides an application of a foam copper-based phase change energy storage composite material in solar thermal management.

[0017] The beneficial effects of the present invention are: The copper foam-based phase-change energy storage composite material provided by the present invention utilizes copper foam as a porous thermal conductor, paraffin wax as a phase-change material, a graphene-based substance as a modifier, and polyvinyl alcohol modified with copper nanomaterials as a binder, combined with a thickener. The resulting material exhibits excellent thermal conductivity. Furthermore, the composite material exhibits excellent cyclic stability, with minimal latent heat loss after multiple charge and discharge cycles. This allows for long-term, stable application in solar thermal management, effectively regulating temperature, improving solar energy utilization efficiency, and reducing energy consumption, resulting in significant economic and environmental benefits. DETAILED DESCRIPTION

[0018] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention and are not intended to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0019] In the following examples, the compound monomers and related reagents used can be purchased from the market. Among them, polyvinyl alcohol was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd. with CAS No. 9002-89-5 and item No. 360627; commercial foam copper was purchased from Kunshan Yinghuixiong Electronic Technology Co., Ltd. with item No. 390 and a pore size of 0.1-10 mm.

[0020] The following examples and comparative examples all include the following steps: The preparation method of adhesive AE is as follows: S3-1: Dissolve 2 g of copper salt in deionized water, add 2 g of sodium bicarbonate, stir evenly, transfer to an autoclave, react at 250°C for 18 h, and then centrifuge, wash, filter, and dry to obtain copper nanomaterials; S3-2: Dissolve polyvinyl alcohol in deionized water, heat to 85°C, and stir to completely dissolve it to form a polyvinyl alcohol solution. Add copper nanomaterials to the polyvinyl alcohol solution, ultrasonically disperse it for 2 hours, then transfer it to a polytetrafluoroethylene mold, put it in the refrigerator and freeze it for 16 hours. After thawing, put it back into the refrigerator. Repeat this cycle 3 times to obtain the adhesive.

[0021] Table 1

[0022] Preparation of copper foam: Copper powder with a particle size of 3 μm and anhydrous calcium chloride are evenly mixed in a mass ratio of 4:1, water is added to form a mixture, the copper powder and anhydrous calcium chloride are fully mixed, and then pressed to form a blank and dried; the dried blank is sintered in a nitrogen atmosphere, the temperature is raised to 830°C at a heating rate of 10°C / min, and maintained for 1-3 hours to obtain a sintered blank; the sintered blank is soaked in running water for 30-60 minutes. After the soaking is completed, the water is removed by centrifugation, and then dried to obtain foamed copper.

[0023] Preparation of composite materials: After the paraffin is heated to 70°C and completely dissolved, a thickener is added and mixed evenly to obtain modified paraffin; the modified paraffin, modifier, and adhesive are then compounded with foam copper by vacuum impregnation. The vacuum impregnation pressure is -0.1 MPa, the reaction temperature is 120°C, and the mixture is impregnated for 30 minutes and then cooled to room temperature. The composite material is obtained by repeated impregnation three times under these conditions.

[0024] Example 1 provides a foam copper-based phase change energy storage composite material, wherein the raw materials for preparing the composite material include 30g of foam copper, 16g of graphene, 35g of paraffin wax, 1g of polyurethane and 1.5g of adhesive A, wherein the pore size of the foam copper is 450μm.

[0025] Example 2 provides a foam copper-based phase change energy storage composite material, wherein the raw materials for preparing the composite material include 35g of foam copper, 15g of graphene oxide, 25g of paraffin wax, 2g of organic bentonite and 2g of adhesive B, wherein the pore size of the foam copper is 300μm.

[0026] Example 3 provides a foam copper-based phase change energy storage composite material, wherein the raw materials for preparing the composite material include 40g of foam copper, 20g of hydroxylated graphene, 45g of paraffin wax, 5g of polypropylene and 5g of adhesive C, wherein the pore size of the foam copper is 500μm.

[0027] Example 4 provides a foam copper-based phase-change energy storage composite material. The components and preparation method used are basically the same as those in Example 1, except that the pore size of the foam copper is 550 μm.

[0028] Example 5 provides a foam copper-based phase-change energy storage composite material. The components and preparation method used are basically the same as those in Example 1, except that the adhesive A is replaced by adhesive D.

[0029] Example 6 provides a foam copper-based phase change energy storage composite material. The components and preparation method used are basically the same as those in Example 1, except that the adhesive A is replaced by adhesive E.

[0030] Example 7 provides a foam copper-based phase-change energy storage composite material. The components and preparation method used are basically the same as those in Example 1, except that the foam copper is replaced with commercial foam copper.

[0031] Comparative Example 1 provides a foam copper-based phase-change energy storage composite material. The components and preparation method used are basically the same as those in Example 1, except that the adhesive A is replaced with polyvinyl alcohol.

[0032] The test method is as follows: Phase transition temperature: Differential scanning calorimetry (DSC) was used. Test conditions: The temperature range for heating and cooling was 25-100°C. The phase transition temperatures of the copper-based phase change energy storage composite materials prepared in Examples 1-7 and Comparative Example 1 were measured. Enthalpy values ​​were calculated from the DSC curves after 1000 cycles. Thermal conductivity: The thermal conductivity of the copper-based phase change energy storage composite materials prepared in Examples 1-7 and Comparative Example 1 was tested using a thermal constant analyzer TPS 2500S from Hot Disk, Sweden. The test results are shown in Table 2.

[0033] Table 2

[0034] It can be clearly seen from Examples 1-3 that the copper foam-based phase change energy storage composite material provided by the present invention is prepared by using copper foam as a porous heat conductor, paraffin wax as a phase change material, graphene-based substances as modifiers, modified polyvinyl alcohol as a binder, and a thickener. The copper foam-based phase change energy storage composite material has a phase transition temperature of 50-55°C and a thermal conductivity of 0.808-0.945 W·m - ¹·K - ¹, maintaining an enthalpy of 200-213 J / g after 1,000 cycles, demonstrating high stability and a long service life. The use of copper nanomaterial-modified polyvinyl alcohol as a binder effectively enhances the bonding between the copper foam and paraffin wax, significantly accelerating heat transfer within the phase-change material. Consequently, this type of copper foam-based phase-change energy storage composite material, with its high thermal conductivity, high stability, and long service life, demonstrates broad application prospects in solar thermal management and is expected to be further promoted and applied.

[0035] By comparing Example 1 with Example 4 and Example 7, it can be found that when a foam copper with a suitable pore size is used and prepared by the preparation method provided by the present invention, and modified polyvinyl alcohol is used as a binder, the prepared foam copper-based phase change energy storage composite material performs better in thermal conductivity, stability and service life.

[0036] Comparison of Example 1 with Comparative Example 1 shows that using the modified polyvinyl alcohol provided by the present invention as a binder can effectively improve the thermal conductivity, stability, and service life of the foamed copper-based phase-change energy storage composite material. Comparison of Example 1 with Examples 5-6 shows that when the qualities of the copper nanomaterial and polyvinyl alcohol used as the binder raw materials are within a reasonable range, the resulting foamed copper-based phase-change energy storage composite material can exhibit even better thermal conductivity, stability, and service life.

[0037] In summary, the copper foam-based phase-change energy storage composite material provided by the present invention utilizes copper foam as a porous thermal conductor, paraffin wax as a phase-change material, a graphene-based material as a modifier, and polyvinyl alcohol modified with copper nanomaterials as a binder, combined with a thickener. The resulting material exhibits excellent thermal conductivity, maintains a high enthalpy value after 1,000 cycles, and exhibits high stability and a long service life. These properties significantly expand the application scope of this material in the field of solar thermal management, laying a solid foundation for its in-depth application in this field.

[0038] The above embodiments are only for illustrating the technical concept and features of the present invention. Its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A foam copper-based phase change energy storage composite material, characterized in that: The raw materials for preparing the composite material include the following components by weight: 30-50g of foamed copper, 15-30g of a modifier, 20-50g of paraffin wax, 1-10g of a thickener, and 1-5g of an adhesive, wherein the adhesive is modified polyvinyl alcohol; The raw materials for preparing the modified polyvinyl alcohol include copper nanomaterials and polyvinyl alcohol, and the mass ratio of the copper nanomaterials to the polyvinyl alcohol is (0.2-1.5):

1.

2. The foam copper-based phase change energy storage composite material according to claim 1, characterized in that: The preparation method of the modified polyvinyl alcohol comprises the following steps: S3-1: Dissolve copper salt in deionized water, add an additive, stir evenly, transfer to an autoclave, react at 180-280°C for 12-48 hours, and then post-treat to obtain copper nanomaterials; S3-2: Dissolve polyvinyl alcohol in deionized water, heat to 80-95°C, and stir to completely dissolve it to form a polyvinyl alcohol solution. Add copper nanomaterials to the polyvinyl alcohol solution, ultrasonically disperse it for 1-2 hours, then transfer it to a polytetrafluoroethylene mold, put it in the refrigerator and freeze it for 12-18 hours. After thawing, put it back into the refrigerator. Repeat this cycle 2-5 times to obtain modified polyvinyl alcohol.

3. The foam copper-based phase change energy storage composite material according to claim 2, characterized in that: The copper salt in step S3-1 includes one or more of copper sulfate, copper chloride and copper acetate.

4. The foam copper-based phase change energy storage composite material according to claim 1, characterized in that: The modifier comprises one or more of graphene, graphene oxide, and hydroxylated graphene.

5. The foam copper-based phase change energy storage composite material according to claim 1, characterized in that: The thickener comprises one or more of polyurethane, organic bentonite and polyacrylic acid.

6. The foam copper-based phase change energy storage composite material according to claim 1, characterized in that: The pore size of the foam copper is 300-500 μm.

7. The foam copper-based phase change energy storage composite material according to claim 6, characterized in that: The preparation method of the foamed copper comprises the following steps: uniformly mixing copper powder and calcium chloride, adding water to form a mixture, pressing to form a blank, and drying; sintering the dried blank in a nitrogen atmosphere, heating the temperature to 800-900°C at a heating rate of 5-10°C / min, and maintaining the temperature for 1-3 hours to obtain a sintered blank; soaking the sintered blank in running water for 30-60 minutes, removing water therefrom by centrifugation after soaking, and then drying to obtain the foamed copper.

8. The method for preparing the foamed copper-based phase-change energy storage composite material according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: heating the paraffin and completely dissolving it, adding a thickener, and mixing them evenly to obtain modified paraffin; and then compounding the modified paraffin, the modifier, and the adhesive with foam copper through vacuum impregnation to obtain a foam copper-based phase change energy storage composite material.

9. Use of the foam copper-based phase change energy storage composite material according to any one of claims 1 to 7 in solar thermal management.

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