Preparation method of long-acting heat storage controllable heat release phase change material

Abstract

The application belongs to the technical field of energy storage materials, and particularly relates to a long-acting heat storage controllable heat release phase change material and a preparation method thereof. The long-acting heat storage controllable heat release phase change material disclosed by the application comprehensively utilizes the crystallization characteristics of sugar alcohol phase change materials and the control effect of hydrogel skeleton materials on the molecular movement of phase change materials, regulates and controls the crystallization rate and supercooling stability of the phase change materials, so that the phase change materials can store high-temperature latent heat at room temperature for a long time, and can controllably release the stored phase change latent heat under external stimulation. The long-acting heat storage controllable heat release phase change material can solve the problems of high-efficiency heat preservation, easy loss of latent heat and uncontrollable heat release of phase change materials.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy storage materials, and particularly relates to a preparation method of a long-acting heat storage controllable heat release phase change material. BACKGROUND

[0002] With the development of industry, people's demand for energy is gradually increasing, however, the mismatch of time and space of existing energy utilization technology limits the energy utilization efficiency. The phase change material (PCM) for the phase change heat storage technology of heat storage medium is considered to be an effective method to solve the time and space mismatch of intermittent renewable energy in supply and demand, which can greatly improve the energy utilization rate. The PCM applied to the phase change heat storage should have high phase change latent heat, good phase change dynamics and as small volume change as possible. Therefore, the solid-liquid PCM is the most studied PCM at present. However, the solid-liquid PCM will repeatedly present a liquid state in the use process, which brings potential leakage risk. Therefore, the form-stable phase change material (FPCM) emerges as the times require. The FPCM is formed by adsorbing the solid-liquid PCM in a porous support material. It has the advantages of wide source of support material, large phase change latent heat and easy incorporation of various functional fillers, thereby becoming a research hotspot of phase change materials in recent years.

[0003] Among the reported PCMs, sugar alcohol PCMs are highly concerned due to their extremely high phase change latent heat. The melting temperature of the sugar alcohol PCMs is higher than room temperature, so good heat preservation measures are needed to avoid the loss of latent heat. However, the crystallization process of the molten sugar alcohol is usually accompanied by obvious supercooling phenomenon, which provides the possibility of keeping the molten state of the sugar alcohol PCMs at room temperature at low cost and avoiding the loss of latent heat, and thus generates a new type of PCM, namely, the "spatiotemporal phase change material (SPCM)". However, supercooling as a common physical and chemical phenomenon is not stable and is affected by many factors. Therefore, how to maintain the sugar alcohol PCMs in a molten state at room temperature and effectively and controllably induce the crystallization of the supercooled molten sugar alcohol to realize controllable heat release is the key to the development and application of SPCM.

[0004] In view of this, the application is provided. SUMMARY

[0005] The application aims to provide a long-acting heat storage controllable heat release phase change material and a preparation method thereof. The application solves the problems of easy loss of latent heat of the phase change material and uncontrollable heat release.

[0006] In order to achieve the above-mentioned object of the present application, the basic idea of the present application is: comprehensively utilizing the crystallization characteristics of sugar alcohol phase change materials and the control effect of hydrogel skeleton materials on the movement of phase change material molecules, regulating the crystallization rate and supercooling stability of phase change materials, so that they can store high-temperature latent heat at room temperature for a long time, and can controllably release the stored phase change latent heat under external stimulation, and have good light-heat conversion capacity.

[0007] According to the above idea, the preparation method of the long-acting heat storage controllable release heat phase change material includes the following steps:

[0008] S1, mixing organic phase change materials in a certain proportion, heating to 10℃ above the phase change temperature to completely melt;

[0009] S2, adding polyvinyl alcohol to the mixed phase change material and heating to completely dissolve;

[0010] S3, adding acrylic acid, N,N-methylene bisacrylamide, ammonium persulfate and filler to the mixed solution, and heating to uniformly disperse;

[0011] S4, after several freeze-thaw cycles, drying the moisture to obtain the long-acting heat storage controllable release heat phase change material.

[0012] Preferably, in the step S1, the organic phase change material is two or more of erythritol, xylitol, sorbitol, mannitol, inositol, and galactitol.

[0013] Preferably, in the step S2, the addition amount of polyvinyl alcohol is (0.1-2):1 by mass ratio to the phase change material.

[0014] Preferably, in the step S3, the addition amount of acrylic acid is (0.05-1):1 by mass ratio to polyvinyl alcohol.

[0015] Preferably, in the step S3, the addition amount of N,N-methylene bisacrylamide is (0.05-1):1 by mass ratio to polyvinyl alcohol.

[0016] Preferably, in the step S3, the addition amount of ammonium persulfate is (0.05-1):1 by mass ratio to polyvinyl alcohol.

[0017] Preferably, in the step S3, the filler is at least one of graphite nanosheet, metal nanowire, carbon nanotube, graphene, and MXene.

[0018] Preferably, in the step S3, the addition amount of filler is (0.05-1):1 by mass ratio to polyvinyl alcohol.

[0019] Preferably, in the step S4, the freeze-thaw cycle condition is: low temperature-197~-10℃, high temperature 10~50℃, and the cycle number is 1-5 times.

[0020] The preparation method of the long-acting heat storage controllable heat release phase change material is used to prepare the composite phase change material with controllable heat release characteristics.

[0021] The long-acting heat storage controllable heat release phase change material and the preparation method thereof have the following advantages and positive effects:

[0022] 1. The composite phase change material obtained by compounding a plurality of sugar alcohol phase change materials has the advantages of high latent heat, good supercooling stability and controllable heat release.

[0023] 2. The polyvinyl alcohol gel is used as a skeleton, which can effectively control the movement characteristics of the phase change material molecules after liquefaction, further improve the supercooling stability and controllable heat release performance, and ensure efficient coating of the phase change material.

[0024] 3. The preparation process is simple, the material source is wide, the repeatability is good, the preparation period is short, and the application is easy.

[0025] 4. The long-acting heat storage controllable heat release phase change material can solve the problems of efficient heat preservation, loss of latent heat and uncontrollable heat release of the phase change material, has good light-heat conversion and latent heat storage performance, and can be applied to outdoor thermal management and other fields.

[0026] The technical solutions of the present application will be further described in detail below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 DSC curves of the long-acting heat storage controllable heat release phase change materials obtained in Examples 1, 2 and 3 and polyhydric sugar alcohols;

[0028] Figure 2 The exothermic curve of the long-acting heat storage controllable heat release phase change material obtained in Example 1 after cooling to room temperature under external mechanical stimulation. DETAILED DESCRIPTION

[0029] The embodiments of the present application will be described in detail below with reference to the examples, and those skilled in the art will understand that the following examples are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. The specific conditions are not specified in the examples, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be purchased on the market.

[0030] Example 1

[0031] Into a beaker, 6.08 g of xylitol and 1.92 g of erythritol were added, heated to 115°C and fully stirred to mix them well. 20 ml of deionized water was added into the beaker, and after fully dissolved by stirring, 1 g of polyvinyl alcohol was added, heated and stirred in a 95°C water bath until fully dissolved, and after cooling to room temperature, 1 g of acrylic acid, 0.05 g of N,N-methylene bisacrylamide and ammonium persulfate, and 0.06 g of graphite nanosheet were added, and stirred in a 65°C water bath for 5 minutes to disperse them well, and reacted for 1 h at constant temperature, and after cooling to room temperature, three freeze-thaw cycles were performed (-20°C freezing for 2 h, and room temperature thawing for 2 h), and after returning to room temperature, moisture was dried at 105°C to obtain a controllable heat-releasing composite phase change material.

[0032] Figure 2 The heat release curve of the long-acting heat storage controllable heat-releasing phase change material obtained in Example 1 under external force stimulation was that when the phase change material was mechanically stimulated, it quickly solidified to release latent heat, and the surface temperature of the material quickly rose. After stopping the mechanical stimulation, the heat release and temperature rise gradually stopped. Stimulation again could again release heat, and this process could be repeated multiple times, and the highest temperature of the sample could be up to 38°C.

[0033] The performance of the long-acting heat storage controllable heat-releasing phase change material was detected, and the liquid phase of the composite phase change material did not leak, the latent heat was 144 J / g, the melting point was 73°C, and the light-heat conversion efficiency was 90%.

[0034] Example 2

[0035] A long-acting heat storage controllable heat-releasing phase change material preparation method, except that the feeding amount of xylitol and erythritol was 5.32 g and 1.68 g respectively, other operation steps were the same as Example 1.

[0036] The performance of the long-acting heat storage controllable heat-releasing phase change material was detected, and the liquid phase of the composite phase change material did not leak, the latent heat was 96 J / g, the melting point was 68°C, and the light-heat conversion efficiency was 87%.

[0037] Example 3

[0038] A long-acting heat storage controllable heat-releasing phase change material preparation method, except that the feeding amount of xylitol and erythritol was 4.56 g and 1.44 g respectively, other operation steps were the same as Example 1.

[0039] The performance of the long-acting heat storage controllable heat-releasing phase change material was detected, and the liquid phase of the composite phase change material did not leak, the latent heat was 72 J / g, the melting point was 65°C, and the light-heat conversion efficiency was 76%.

[0040] Example 4

[0041] A long-acting heat storage controllable heat release phase change material preparation method, except that sorbitol is used to replace xylitol, other operation steps are the same as example 1.

[0042] The performance of the long-acting heat storage controllable heat release phase change material is detected, the liquid phase of the composite phase change material does not leak, the latent heat is 64J / g, and the melting point is 110℃.

[0043] Example 5

[0044] A long-acting heat storage controllable heat release phase change material preparation method, except that sorbitol and mannitol are used to replace xylitol and erythritol, other operation steps are the same as example 1.

[0045] The performance of the long-acting heat storage controllable heat release phase change material is detected, the liquid phase of the composite phase change material does not leak, the latent heat is 71J / g, and the phase change temperature is 112℃.

[0046] Example 6

[0047] A long-acting heat storage controllable heat release phase change material preparation method, except that the amount of acrylic acid used is 0.5g, other operation steps are the same as example 1.

[0048] The performance of the long-acting heat storage controllable heat release phase change material is detected, the liquid phase of the composite phase change material does not leak, the latent heat is 110J / g, and the phase change temperature is 64℃.

[0049] Example 7

[0050] A long-acting heat storage controllable heat release phase change material preparation method, except that the amount of N,N-methylene bisacrylamide used is 0.01g, other operation steps are the same as example 1.

[0051] The performance of the long-acting heat storage controllable heat release phase change material is detected, the liquid phase of the composite phase change material does not leak, the latent heat is 74J / g, and the phase change temperature is 60℃.

[0052] Example 8

[0053] A long-acting heat storage controllable heat release phase change material preparation method, except that the amount of ammonium persulfate used is 0.01g, other operation steps are the same as example 1.

[0054] The performance of the long-acting heat storage controllable heat release phase change material is detected, the liquid phase of the composite phase change material does not leak, the latent heat is 71J / g, and the phase change temperature is 63℃.

[0055] Example 9

[0056] A long-acting heat storage controllable heat release phase change material preparation method, except that the amount of graphite nanosheet used is 0.12g, other operation steps are the same as example 1.

[0057] The performance of the long-acting heat storage controllable heat release phase change material is detected, the liquid phase of the composite phase change material does not leak, the latent heat is 61J / g, and the phase change temperature is 62℃.

[0058] Example 10

[0059] A long-acting heat storage controllable heat release phase change material preparation method, except that the freeze-thaw cycle temperature is changed to -197℃ to room temperature, and other operation steps are the same as those in Example 1.

[0060] The performance of the long-acting heat storage controllable heat release phase change material is detected, the liquid phase of the composite phase change material leaks, the latent heat is 45J / g, and the phase change temperature is 80℃.

[0061] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A long-term heat storage controllable heat release phase change material, characterized in that, By regulating the crystallization rate and supercooling stability of the phase change material, it can store high-temperature latent heat at room temperature for a long time, and can controllably release the stored phase change latent heat under external stimulation, and has good light-heat conversion efficiency, and can be applied to outdoor warmth and heat management. The long-acting heat storage controllable heat release phase change material is prepared by the following method: S1, mix the organic phase change material and heat it to completely melt, the organic phase change material is two or more of erythritol, xylitol, sorbitol, mannitol, inositol, galactitol; S2, add polyvinyl alcohol to the mixed phase change material and heat to completely dissolve; S3, add acrylic acid, N,N-methylene bisacrylamide, ammonium persulfate and filler to the mixed solution, heat and uniformly disperse; S4, after freeze-thaw cycle, dry the moisture to obtain the long-acting heat storage controllable heat release phase change material, the freeze-thaw cycle conditions are: low temperature-197-10℃, high temperature 10-50℃, cycle number is 1-5 times.

2. The preparation method of the long-lasting thermal storage and controllable exothermic phase change material according to claim 1, characterized in that: In S2, the addition amount of polyvinyl alcohol is (0.1-2):1 compared with the mass of the phase change material.

3. The preparation method of the long-lasting heat storage and controllable exothermic phase change material according to claim 1, characterized in that: In S3, the addition amount of acrylic acid is (0.05-1):1 compared with the mass of polyvinyl alcohol, the addition amount of N,N-methylene bisacrylamide is (0.05-1):1 compared with the mass of polyvinyl alcohol, the addition amount of ammonium persulfate is (0.05-1):1 compared with the mass of polyvinyl alcohol, and the addition amount of filler is (0.05-1):1 compared with the mass of polyvinyl alcohol.

4. The preparation method of the long-lasting thermal storage and controllable exothermic phase change material according to claim 1, characterized in that: In S3, the filler is at least one of graphite nanosheet, metal nanowire, carbon nanotube, graphene and MXene.

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