High-heat-storage-density phase-change composite material and preparation method therefor

Abstract

A high-heat-storage-density phase-change composite material and a preparation method therefor. The preparation method comprises the following steps: 1) uniformly mixing oxalic acid dihydrate, an organic acid, magnesium sulfate heptahydrate and an alkylolamide phosphate according to a ratio while stirring, so as to obtain a mixture A; 2) sealing and maintaining the temperature of the mixture A for a certain time, and then magnetically stirring same for a certain time at a constant temperature, so as to obtain a mixture B; and 3) naturally cooling the mixture B to room temperature for solidification, so as to obtain a high-heat-storage-density phase-change composite material. The phase-change composite material has a high volume heat-storage density and a melting temperature at 65-75°C, and also has the characteristics of good heat cycle performance, low flammability and low corrosivity. The phase-change composite material can be applied to environment temperature management during instantaneous heat release of an electronic device.

Description

High heat storage density composite phase change material and preparation method thereof TECHNICAL FIELD

[0001] The present application belongs to the technical field of ambient temperature control materials, and particularly relates to a high heat storage density composite phase change material and a preparation method thereof. BACKGROUND

[0002] Many precision electronic components (such as 5G devices, radars, etc.) will generate a large amount of heat when working, and the heat will cause the ambient temperature to rise. When the ambient temperature is higher than the required working temperature of the working system, it will cause the device efficiency and service life to decrease, and even damage. To solve this problem, the current main solution is to use a phase change material with a suitable phase change temperature to adhere or wrap the electronic components, and to control the ambient temperature within the device working temperature range by absorbing the generated heat, so as to achieve ambient temperature management. The phase change energy storage material can be used to absorb the heat released by the system to keep the ambient temperature relatively stable within a certain period of time, so as to achieve the purpose of adjusting and controlling the ambient temperature of the phase change material. It is a good ambient temperature control material. The phase change material applied to the temperature control of electronic components generally requires a phase change temperature of 65-75℃, and the larger the phase change latent heat is, the better. The material commonly used for ambient temperature thermal management at present is high-purity paraffin with a carbon chain length greater than 32, and its melting latent heat value is 200-240J / g. However, it has the disadvantages of flammability and high cost. In addition, most of the phase change materials on the market cannot meet the needs of ambient temperature control.

[0003] Dihydrated oxalic acid has super-high phase change latent heat (364J / g) and the advantages of being cheap and easy to obtain compared with relatively high-purity paraffin. However, when applied to ambient temperature control, it also has the disadvantages of high phase change temperature (99℃) and high corrosiveness, and thus cannot be directly used for electronic component ambient temperature control. At present, there are few studies on dihydrated oxalic acid-based composite materials at home and abroad. South China Institute of Technology obtained a composite phase change material with a phase change temperature of 56.13℃ and a phase change latent heat of 246.9J / g by compounding dihydrated oxalic acid and twelve-water aluminum ammonium sulfate (Wang Kai, Preparation and Performance of Dihydrated Oxalic Acid-Ammonium Alum Eutectic / Zirconia Modified Expanded Graphite Composite Phase Change Material, Master Thesis of South China Institute of Technology, 2021); Qinghai Salt Lake Institute of Chinese Academy of Sciences obtained a composite phase change material with a phase change temperature of 88.7℃ and a phase change latent heat of 328.2J / g by compounding dihydrated oxalic acid and sodium chloride (Han Lipeng, Tolerance Research of Dihydrated Oxalic Acid Phase Change Energy Storage Material, Master Thesis of Qinghai Salt Lake Institute of Chinese Academy of Sciences, 2019). Some literature also reports that dihydrated oxalic acid and borax can be compounded to obtain a phase change material with a phase change temperature of 87.3℃ and a phase change latent heat of 344J / g (Renewable Energy, 2019, (136): 657-663).

[0004] Although the above studies reduce the phase transition temperature by combining dihydrate oxalic acid and soluble inorganic salt to form a eutectic or co-crystal mixture, the melting temperature does not enter the commonly used environmental temperature range of electronic components, and the addition of inorganic salt increases the ionic conductivity of the phase change material when melting, which further increases the electrochemical corrosion of the metal. SUMMARY

[0005] In view of the deficiencies of the phase change materials in the current environmental temperature control field, such as flammability and high cost of high-purity paraffin, and the melting point of the existing dihydrate oxalic acid phase change material does not meet the requirements of environmental temperature control and has high corrosion to the container material, the application provides a high heat storage density composite phase change material and a preparation method thereof.

[0006] To achieve the above technical purposes and achieve the above technical effects, the application is implemented by the following technical solutions:

[0007] The application provides a preparation method of a high heat storage density composite phase change material, comprising the following steps:

[0008] 1) Under stirring conditions, dihydrate oxalic acid, organic acid, magnesium sulfate heptahydrate, and alkyl alcohol amide phosphate are uniformly mixed according to a proportion to obtain a mixture A;

[0009] 2) After the mixture A is sealed and kept warm for a certain time, it is subjected to constant temperature magnetic stirring for a certain time to obtain a mixture B;

[0010] 3) The mixture B is naturally cooled to room temperature to solidify, and a high heat storage density composite phase change material is obtained.

[0011] Further, in step 1), the mass ratio of dihydrate oxalic acid, organic acid, magnesium sulfate heptahydrate, and alkyl alcohol amide phosphate is 40:60:1:0.05-0.4.

[0012] Further, in step 1), the mass ratio of dihydrate oxalic acid, organic acid, magnesium sulfate heptahydrate, and alkyl alcohol amide phosphate is 40:60:1:0.1.

[0013] Further, in step 1), the organic acid is glutaric acid.

[0014] Further, in step 2), the sealing and keeping warm temperature is controlled at 95-105℃, and the keeping warm time is controlled at 2.5-3.5h.

[0015] Further, in step 2), the sealing and keeping warm temperature is controlled at 100℃, and the keeping warm time is controlled at 3h.

[0016] Further, in step 2), the temperature of the constant temperature magnetic stirring is 100℃, and the time control is 20-30 min.

[0017] Further, in step 2), the temperature of the constant temperature magnetic stirring is 100℃, and the time control is 25 min.

[0018] The application also provides a high heat storage density composite phase change material obtained by the above preparation method.

[0019] The application has the following beneficial effects:

[0020] 1. Compared with high-purity paraffin with a melting point in the range of 65-75℃, the heat storage density of the obtained composite phase change material is obviously higher than that of paraffin, the composite phase change material cannot burn by itself (paraffin is flammable), and the production cost is significantly reduced.

[0021] 2. Compared with other disclosed composite phase change materials of dihydrate oxalic acid, the obtained composite phase change material does not use inorganic salts for compounding, but adjusts the melting point of dihydrate oxalic acid through organic acid, and inhibits the hydrolysis behavior of dihydrate oxalic acid during melting through organic acid, and the material further reduces the corrosion to metal through the joint action of alkyl alcohol amide phosphate.

[0022] 3. The obtained composite phase change material also has the characteristics of good thermal cycle performance, low flammability and low corrosion, and can be applied to the environmental temperature management of electronic equipment during instantaneous heat release.

[0023] Of course, implementing any product of the application does not necessarily need to achieve all the above advantages at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0025] Fig. 1 is a differential scanning calorimetry (DSC) graph of Example 1;

[0026] Fig. 2 is a differential scanning calorimetry (DSC) graph of Example 2;

[0027] Fig. 3 is a differential scanning calorimetry (DSC) graph of Example 3;

[0028] Fig. 4 is a differential scanning calorimetry (DSC) graph of Example 4;

[0029] Fig. 5 is a differential scanning calorimetry (DSC) graph of Example 5;

[0030] Figure 6 is a tafel curve of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0032] Example 1

[0033] Oxalic acid dihydrate, glutaric acid, magnesium sulfate heptahydrate and alkylol amide phosphate ester were uniformly mixed in a mass ratio of 40:60:1:0.05, sealed at 105°C and kept for 2.5h, constant-temperature magnetic stirring was performed at 100°C for 20min, and then the mixture was naturally cooled to room temperature to solidify, thereby obtaining a high heat storage density composite phase change material.

[0034] Example 2

[0035] Oxalic acid dihydrate, glutaric acid, magnesium sulfate heptahydrate and alkylol amide phosphate ester were uniformly mixed in a mass ratio of 40:60:1:0.1, sealed at 100°C and kept for 3h, constant-temperature magnetic stirring was performed at 100°C for 25min, and then the mixture was naturally cooled to room temperature to solidify, thereby obtaining a high heat storage density composite phase change material.

[0036] Example 3

[0037] Oxalic acid dihydrate, glutaric acid, magnesium sulfate heptahydrate and alkylol amide phosphate ester were uniformly mixed in a mass ratio of 40:60:1:0.2, sealed at 100°C and kept for 3h, constant-temperature magnetic stirring was performed at 100°C for 25min, and then the mixture was naturally cooled to room temperature to solidify, thereby obtaining a high heat storage density composite phase change material.

[0038] Example 4

[0039] Oxalic acid dihydrate, glutaric acid, magnesium sulfate heptahydrate and alkylol amide phosphate ester were uniformly mixed in a mass ratio of 40:60:1:0.3, sealed at 100°C and kept for 3h, constant-temperature magnetic stirring was performed at 100°C for 25min, and then the mixture was naturally cooled to room temperature to solidify, thereby obtaining a high heat storage density composite phase change material.

[0040] Example 5

[0041] According to the mass fraction ratio of 40:60:1:0.4 of oxalic acid dihydrate, glutaric acid, magnesium sulfate heptahydrate, alkylol amide phosphate, uniformly mixed, sealed 95℃ and heat preservation 3.5h, constant temperature magnetic stirring temperature is 100℃ and time is 30min, natural cooling to room temperature solidification, a high heat storage density composite phase change material is obtained.

[0042] Comparative Example 1

[0043] According to the mass fraction ratio of 40:60:1 of oxalic acid dihydrate, glutaric acid, magnesium sulfate heptahydrate, uniformly mixed, sealed 100℃ and heat preservation 3h, constant temperature magnetic stirring temperature is 100℃ and time is 25min, natural cooling to room temperature solidification, a high heat storage density composite phase change material is obtained.

[0044] The thermal physical property data of Examples 1-5 and the thermal physical property data after 50 cycles are shown in Tables 1 and 2, respectively:

[0045] Table 1 Thermal physical property data of Examples 1-5

[0046] Table 2 Thermal physical property data of Examples 1-5 after 50 thermal cycles

[0047] From the above two tables, it can be seen that the supercooling degree and phase change latent heat of Examples 1 to 5 change little after 50 cycles; considering the volume heat storage density, whether before or after cycling, the phase change latent heat of the sample added with 0.1% alkylol amide phosphate is the largest, and the volume heat storage density is also better, so the sample of Example 2 is the best.

[0048] Corrosion test: the samples of Example 2 and Comparative Example 1 are prepared into 0.5mol / L aqueous solution, and the electrochemical tafel curve of the solution is tested by electrochemical workstation. The results are shown in Table 3, the self-corrosion potential of Example 2 is higher than that of Comparative Example 1, the self-corrosion current is less than that of Comparative Example 1, and the polarization resistance is greater than that of Comparative Example 1. The above results show that the corrosion of Example 2 is smaller than that of Comparative Example 1.

[0049] Table 3 Tafel curve test results of Example 2 and Comparative Example 1

[0050] Self-combustion test: a certain amount of sample of Example 2 is wrapped with paper, and the outer layer paper is ignited with a lighter. After the outer layer paper burns out, it is observed whether the sample inside can burn spontaneously. The results show that the sample of Example 2 does not show spontaneous combustion behavior, indicating that the sample has good flame retardance.

[0051] The instrument used to measure the phase transition temperature and latent heat of phase transition of the prepared sample is DSC-500B differential scanning calorimeter produced by Shanghai Yinnuo Precision Instrument Co., Ltd. 10 mg of sample is placed in an aluminum crucible with a cover, nitrogen is used as the purging gas and protective gas, and the flow rate is 20 mL / min; the temperature range for testing is: room temperature ~ 100°C; under nitrogen atmosphere, the temperature is raised from room temperature to 100°C at a rate of 3°C / min, and then the temperature is lowered from 100°C to room temperature at a rate of -3°C / min.

[0052] The instrument used to measure the tafel curve of Example 2 and Comparative Example 1 is CH1760E electrochemical workstation produced by Xi'an Chenhua Instrument Co., Ltd., four-electrode method, the reference electrode is a mercury-mercury electrode, the test temperature is room temperature, and the scanning rate is 0.01 V / s.

[0053] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The preferred embodiments do not describe all the details and limit the present application to the specific embodiments. Obviously, many modifications and variations can be made according to the content of the present application. The present application is selected and specifically described in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a high heat storage density composite phase change material, characterized by, The method comprises the following steps: 1) mixing oxalic acid dihydrate, organic acid, magnesium sulfate heptahydrate and alkylolamide phosphate in a proportion under stirring to obtain a mixture A; 2) sealing and keeping the mixture A for a certain time, and then magnetically stirring the mixture B at a constant temperature for a certain time to obtain a mixture B; 3) naturally cooling the mixture B to room temperature to solidify, thereby obtaining a high heat storage density composite phase change material.

2. The production method according to claim 1, characterized by, In step 1), the mass ratio of oxalic acid dihydrate, organic acid, magnesium sulfate heptahydrate and alkylolamide phosphate is 40:60:1:0.05-0.

4.

3. The production method according to claim 2, characterized by, In step 1), the mass ratio of oxalic acid dihydrate, organic acid, magnesium sulfate heptahydrate and alkylolamide phosphate is 40:60:1:0.

1.

4. The method of claim 1, wherein, In step 1), the organic acid is glutaric acid.

5. The preparation method according to claim 1, characterized in that, In step 2), the sealing and keeping temperature is controlled at 95-105℃, and the keeping time is controlled at 2.5-3.5h.

6. The production method according to claim 5, wherein In step 2), the sealing and keeping temperature is controlled at 100℃, and the keeping time is controlled at 3h.

7. The preparation method according to claim 1, characterized in that, In step 2), the temperature of the constant temperature magnetic stirring is 100℃, and the time is controlled at 20-30min.

8. The method of claim 7, wherein, In step 2), the temperature of the constant temperature magnetic stirring is 100℃, and the time is controlled at 25min.

9. A high heat storage density composite phase change material obtained by the preparation method of any one of claims 1-8.

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