Supercooled plastic crystal composite material with controllable magnetic field as well as preparation method and heat storage application of supercooled plastic crystal composite material

Abstract

The invention belongs to the field of heat storage application, and particularly relates to a supercooled plastic crystal composite material with a controllable magnetic field and a preparation method and heat storage application of the supercooled plastic crystal composite material. The performance that the supercooled plastic crystal can be regulated and controlled by pressure is utilized, after the supercooled plastic crystal is mixed with the magnetic powder, attraction force can be generated on the magnetic powder through a magnetic field, then stress is generated on the supercooled plastic crystal, and therefore non-contact magnetic field induction plastic crystal composite materials are subjected to phase change in the indirect mode. Therefore, the supercooled plastic crystal material is combined with the magnetic powder, the limitation of an induction phase change mode of the current supercooled plastic crystal material is expected to be solved, non-contact and non-damage magnetic field controllable phase change heat release is realized, and the application scene of the supercooled plastic crystal material is greatly expanded.

Description

Technical Field

[0001] The present invention belongs to the field of heat storage applications, and specifically relates to a supercooled plastic crystal composite material with controllable magnetic field, a preparation method thereof, and heat storage applications. Background Art

[0002] For the future carbon neutral development, it is urgent to develop a decarbonized heat storage system. Globally, winter house and water heating accounts for 60% of building energy consumption, which is the energy consumption for human life and thermal comfort. Heating or cooling in the home can be replaced by sustainable solar-thermal energy. However, due to the huge time mismatch between the abundant solar energy in summer and the high heating demand in winter, especially in some extreme climate regions, this is a major technical obstacle to collecting solar energy for heating. Therefore, the development of new energy storage methods for cross-seasonal heat storage technology is very important to alleviate the mismatch between time and thermal energy.

[0003] Supercooled plastic crystal materials have an irreversible compression effect, which is specifically manifested in the transition from ordered to glassy phase after endothermic absorption at high temperature. However, the glassy phase can be maintained to a temperature far below the phase transition point, and phase transition heat release (several hundred J kg) can be achieved at low temperatures by a relatively small pressure. -1 k -1 ). Therefore, by utilizing the irreversible compression effect of this type of supercooled plastic crystal material, it is expected to achieve a long-term, wide-temperature, and cross-regional storage effect of heat. Although plastic crystal materials exhibit excellent thermodynamic properties, they are limited by contact pressure regulation, which will limit the widespread application of such materials. At present, pressure or long-term ultrasound is mainly used to induce phase change in materials. This contact or long-term stress-induced phase change method is bound to cause irreversible damage to the material and thus reduce the service life of the material. Therefore, under the premise of avoiding damage to the material, a non-contact field is introduced to controllably induce the phase change of the material, which will greatly improve the application flexibility of supercooled plastic crystal materials. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a supercooled plastic crystal composite material with controllable magnetic field and its heat storage application, by mixing a plastic crystal material with a supercooled phase with NbFeB and Fe 3 O 4 The magnetic powder is uniformly mixed and ground in a certain mass ratio to prepare a composite phase change material. This method can use a small magnetic field to induce phase change in the supercooled plastic crystal composite material.

[0005] The present invention adopts the following technical solution:

[0006] A magnetic field controllable supercooled plastic crystal composite material is prepared by mixing a plastic crystal material with a supercooled phase and magnetic powder.

[0007] The plastic crystal material with supercooled phase is erythritol C 4 H 10 O 4 、Magnesium chloride hexahydrate MgCl 2 6H 2 O, adipic acid HOOC (CH 2 ) 4 COOH, galactitol C 6 H 14 O 6 and 2-amino-2-methyl-1,3-propanediol H 2 N(CH 3 )C(CH 2 OH) 2 (AMP) or more.

[0008] The magnetic powder is NdFeB, Fe 3 O 4 , Fe, SmCo, NdNiCo or more, the mass proportion of the magnetic powder is 20-90%, preferably 20-80%, more preferably 20-60%.

[0009] A method for preparing a magnetic field controllable supercooled plastic crystal composite material is characterized by: mixing and grinding a plastic crystal material with a supercooled phase with magnetic powder, heating it to above the glass phase transition temperature, keeping it warm, and naturally cooling it to room temperature.

[0010] Furthermore, the particle size of the ground magnetic powder is less than 10 μm, preferably 0.1 to 10 μm, and the particle size of the ground plastic crystal material with a supercooled phase is between 100 and 500 μm.

[0011] Furthermore, the heating temperature is higher than the phase transition temperature of the glass phase, preferably 10 to 50° C. higher than the phase transition temperature of the glass phase, and the heat preservation time is 1 to 3 minutes.

[0012] The invention discloses an application of a supercooled plastic crystal composite material with controllable magnetic field as a heat storage material, wherein the application process includes a heat release process and a heat storage process of the supercooled plastic crystal composite material.

[0013] Furthermore, the exothermic process is to apply a magnetic field to the supercooled plastic-crystalline composite material to induce a phase change and release heat.

[0014] When the magnetic field size is 40 to 60 mT and the induction time is 1 to 3 minutes, a strain of 0.5 to 2% can be generated for 0.5 to 1 g of supercooled plastic crystal composite material, after which a phase change begins to occur. After the phase change is triggered, the phase change of the material has spontaneous diffusion. After 100 seconds, the material completely changes phase and generates a temperature change of 100 to 120°C / g.

[0015] Furthermore, the heat storage process is to heat the supercooled plastic crystal composite material after heat release to a temperature above the phase transition point of the glass phase, preferably 10 to 50°C higher than the phase transition point, keep it warm for 1 to 3 minutes, and then naturally cool it to room temperature.

[0016] Advantages and beneficial effects of the present invention:

[0017] The present invention utilizes the pressure-controlled performance of supercooled plastic crystals. After mixing them with magnetic powders, the magnetic field can be used to generate attraction to the magnetic powders and then generate stress on the supercooled plastic crystals, thereby indirectly achieving a non-contact magnetic field-induced phase change of the plastic crystal composite material. Based on this, combining this type of supercooled plastic crystal material with magnetic powders is expected to solve the limitations of the current supercooled plastic crystal material induction phase change method, and achieve non-contact and non-destructive magnetic field-controlled phase change exotherm, which will greatly expand the application scenarios of supercooled plastic crystal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the technical principle of the phase change of the supercooled plastic crystal composite material of the present invention under the induction of a small magnetic field;

[0019] Figure 2 This is a non-contact full-field strain test diagram of the supercooled plastic-crystalline composite material prepared in Example 1;

[0020] Figure 3 This is a physical picture of the phase transition of the supercooled plastic crystal composite material prepared in Example 1 under the induction of a small magnetic field;

[0021] Figure 4 This is a physical picture of the phase change of the supercooled plastic crystal composite material prepared in Example 2 under the induction of a small magnetic field. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0023] The object of the present invention is to provide a method for preparing a magnetic field-controllable supercooled plastic crystal composite material and its heat storage application, and its specific implementation methods are as follows.

[0024] Preparation of magnetic field controllable supercooled plastic crystal composites

[0025] Example 1

[0026] S1: Select a plastic crystal material with a supercooled phase, such as erythritol C 4 H 10 O 4 、Magnesium chloride hexahydrate MgCl 2 6H 2 O, adipic acid HOOC (CH 2 ) 4 COOH, galactitol C 6 H 14 O 6 , 2-amino-2-methyl-1,3-propanediol H 2 N(CH 3 )C(CH 2 OH) 2 (AMP) in one or more; in this embodiment, 2-amino-2-methyl-1,3-propanediol H 2 N(CH 3 )C(CH 2 OH) 2 (AMP) as a plastic crystal material with a supercooled phase.

[0027] S2: The above-mentioned plastic crystal material with supercooled phase and magnetic powder are mixed in a certain mass ratio, with magnetic NdFeB as magnetic powder, the mass of plastic crystal material with supercooled phase is 0.5g, and the mass of magnetic powder is 0.125g. 2 Mechanical grinding is performed for 10 minutes under the protection of the material to make the mixture uniform. After grinding, the particle size of the plastic crystal material with the supercooled phase is between 100-500 μm, and the particle size of the NdFeB magnetic powder is between 5-10 μm.

[0028] S3: Heat the material obtained in S2. In this embodiment, the heating temperature is selected to be 100° C. In particular, in the heating step, the heating temperature needs to exceed the phase transition temperature point (88° C.) of the glass phase change material to make it in a high-temperature plastic crystal state. The heating time is 1 minute, and it is naturally cooled to room temperature to obtain its supercooled plastic crystal phase, that is, to obtain a magnetic field-controllable supercooled plastic crystal composite material.

[0029] Example 2

[0030] S1: Select a plastic crystal material with a supercooled phase, such as erythritol C 4 H 10 O 4 、Magnesium chloride hexahydrate MgCl 2 6H 2 O, adipic acid HOOC (CH 2 ) 4 COOH, galactitol C 6 H 14 O 6, 2-amino-2-methyl-1,3-propanediol H 2 N(CH 3 )C(CH 2 OH) 2 (AMP) in one or more; in this embodiment, 2-amino-2-methyl-1,3-propanediol H 2 N(CH 3 )C(CH 2 OH) 2 (AMP) as a plastic crystal material with a supercooled phase.

[0031] S2: Mix the above-mentioned plastic crystal material with supercooled phase and magnetic powder in a certain mass ratio. 3 O 4 The powder is used as magnetic powder, the mass of the supercooled plastic material is 0.5g, and the mass of the magnetic powder is 0.125g. 2 The mixture was mechanically ground for 10 minutes under the protection of a quartz crystal to make it uniform. The particle size of the supercooled phase plastic material after grinding was between 100-500 μm. 3 O 4 The powder diameter is between 200-300nm.

[0032] S3: heating the material obtained in S2. In this embodiment, the heating temperature is selected to be 100° C. In particular, in the heating step, the heating temperature needs to exceed the phase transition temperature of the glass phase change material so that it is in a high-temperature plastic crystal state. The heating time is 1 minute, and the material is naturally cooled to room temperature to obtain its supercooled plastic crystal phase, that is, a supercooled plastic crystal composite material with controllable magnetic field is obtained.

[0033] Application example (heat storage application process)

[0034] The application of the supercooled plastic crystal composite material as a heat storage material in the present invention includes a heat release process and a heat storage process. The heat release process is carried out by inducing a magnetic field, and then the composite material after heat release is heated and cooled to realize the heat storage process. This cycle allows the supercooled plastic crystal composite material to be reused under non-contact stress.

[0035] The following is an explanation of the principle of induced phase change in the heat release process: the supercooled plastic crystal composite materials prepared in Example 1 and Example 2 are induced to undergo phase change by using a magnetic field generated by a magnet, the magnitude of the induced magnetic field is 40 mT, and the duration is 4 min. Figure 1Since the supercooled plastic crystal composite material is prepared by mixing plastic crystal material with supercooled phase and magnetic powder, during the magnetic field induced phase change process, the magnetic powder in the supercooled plastic crystal composite material moves under the force of the non-contact magnetic field and generates a small stress on the supercooled plastic crystal material, thereby inducing the supercooled plastic crystal material to start phase change and crystallization, and finally forming an ordered crystal phase and releasing a large amount of heat. The first 2 minutes of the induced phase change is the process of generating stress and strain, and 2 minutes later, the supercooled plastic crystal material begins to phase change and releases heat.

[0036] Figure 2 The non-contact full-field strain (DIC) test results of the supercooled plastic crystal material prepared in Example 1 after being subjected to a 40mT magnetic field for 2 minutes are shown. The magnetic powder is subjected to the magnetic field to generate stress on the material, thereby generating strain. The specific test process is as follows: the supercooled plastic crystal composite material prepared in Example 1 is placed in a square glass groove, and then white and black paints are sprayed on the sample in sequence to form a speckle image. The displacement vector of the pixel point is obtained by tracking (or matching) the position change of all pixel points in the surface speckle image of the supercooled plastic crystal composite material under the action of a 40mT magnetic field (the magnet is placed at the edge of the supercooled plastic crystal composite material) within 2 minutes by a CCD camera, thereby obtaining the full-field strain of the surface of the supercooled plastic crystal composite material. The test results show that the supercooled plastic crystal composite material can generate 0.5-2% strain locally within 2 minutes under the induction of the magnet. The strain analysis of DIC first performs algorithm matching on the collected images to obtain the coordinates of discrete spots, and then calculates the displacement vector of each discrete point on the deformed sample. The calculation of full-field strain requires differentiation of displacement. First, the obtained displacement data needs to be denoised and smoothed, and then the strain of the image is calculated using the following strain calculation formula. Where u and v are the corresponding calculated displacements in the x and y directions, respectively.

[0037]

[0038] The magnetic field was induced for 2 minutes, at which time the supercooled plastic crystal composite material began to undergo phase transition after generating sufficient strain. Figure 3 and Figure 4 The actual pictures of the supercooled plastic crystal composite materials prepared in the two examples (where the supercooled plastic crystal is transparent and the magnetic powder is black) at different induction times after the phase change begins. It can be seen from the figure that after the phase change is triggered, the phase change of the material has spontaneous diffusion. Within 100 seconds, the two supercooled plastic crystal composite materials undergo a complete phase change under the induction of a 40mT magnetic field and transform into a white ordered crystalline phase. The phase change process of the supercooled plastic crystal composite material in Example 1 was analyzed by infrared camera temperature change. The results showed that 0.625g of the supercooled plastic crystal composite material in Example 1 produced a temperature change of up to 70.6°C within 100 seconds.

[0039] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A supercooled plastic crystal composite material with controllable magnetic field, characterized in that: The material is prepared by mixing a plastic crystal material having a supercooled phase with magnetic powder.

2. The magnetic field controllable supercooled plastic crystal composite material according to claim 1, characterized in that: The plastic crystal material with supercooled phase is erythritol C4H 10 O4, magnesium chloride hexahydrate MgCl2·6H2O, adipic acid HOOC(CH2)4COOH, galactitol C6H 14 O6 and one or more of 2-amino-2-methyl-1,3-propanediol H2N(CH3)C(CH2OH)2(AMP).

3. The magnetic field controllable supercooled plastic crystal composite material according to claim 1, characterized in that: The magnetic powder is one or more of NdFeB, Fe3O4, Fe, SmCo, and NdNiCo, and the mass proportion of the magnetic powder is 20-90%, preferably 20-80%, and more preferably 20-60%.

4. A method for preparing a magnetic field controllable supercooled plastic crystal composite material according to any one of claims 1 to 3, characterized in that: The plastic crystal material with a supercooled phase is mixed with magnetic powder and ground, the temperature is raised to above the glass phase transition temperature, the temperature is kept, and the mixture is naturally cooled to room temperature.

5. The method for preparing a supercooled plastic crystal composite material with controllable magnetic field according to claim 4, characterized in that: The particle size of the ground magnetic powder is less than 10 μm, preferably 0.1-10 μm, and the particle size of the ground plastic crystal material with a supercooled phase is between 100 and 500 μm.

6. The method for preparing a supercooled plastic crystal composite material with controllable magnetic field according to claim 4, characterized in that: The heating temperature is higher than the phase transition temperature of the glass phase, preferably 10 to 50° C. higher than the phase transition temperature of the glass phase, and the heat preservation time is 1 to 3 minutes.

7. Use of the magnetic field controllable supercooled plastic crystal composite material according to any one of claims 1 to 3 as a heat storage material, characterized in that: The application process includes a heat release process and a heat storage process of the supercooled plastic crystal composite material.

8. The use according to claim 7, characterized in that: The exothermic process is to apply a magnetic field to the supercooled plastic crystal composite material to induce a phase change and release heat.

9. The use according to claim 7, characterized in that: The heat storage process is to heat the supercooled plastic crystal composite material after heat release to a temperature above the phase transition point of the glass phase, preferably 10 to 50°C above the phase transition point, keep it warm for 1 to 3 minutes, and then naturally cool it to room temperature.

10. The use according to claim 8, characterized in that The magnitude of the magnetic field is 40-60 mT, and the induction time is 1-3 minutes.

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