A phase change energy storage-radiation refrigeration composite material for dynamic thermal management and a preparation method thereof

Abstract

The application discloses a dynamic thermal management phase change energy storage-radiation refrigeration composite material and a preparation method thereof, and belongs to the technical field of building and human skin thermal management. The method comprises the following steps: 1, sufficiently melting liquid metal Ga; 2, adding metal particles into the liquid metal Ga; 3, preparing a Ga-based phase change energy storage material; and 4, combining the Ga-based phase change energy storage material with a radiation refrigeration film by using a heat-conducting double-sided adhesive tape to obtain the dynamic thermal management phase change energy storage-radiation refrigeration composite material. The dynamic thermal management phase change energy storage-radiation refrigeration composite material prepared by the application can realize a refrigeration effect below room temperature in a building, and can also realize the functions of daytime heat buffering and nighttime heat releasing, so as to dynamically adjust the temperature. The dynamic thermal management phase change energy storage-radiation refrigeration composite material has good thermoelectric power potential, can generate an output voltage greater than 100 mV in a phase change stage, and can also continuously generate an output voltage of 20 mV-40 mV in a non-phase change stage.

Description

Technical Field

[0001] This invention belongs to the field of building and human skin thermal management technology, specifically relating to a phase change energy storage-radiation cooling composite material for dynamic thermal management and its preparation method. Background Technology

[0002] The frequent occurrence of extreme heatwaves has led to a growing demand for cooling. Traditional cooling technologies, such as air conditioning, generate large amounts of greenhouse gases and waste heat due to excessive use of electricity and refrigerants, exacerbating the greenhouse effect and urban heat island effect. Therefore, in the face of energy shortages and environmental pollution, finding an efficient, environmentally friendly, and energy-saving cooling method is of great significance. Spectral modulation passive radiation cooling technology can emit thermal radiation into the cold universe (≈3K) through an atmospheric transparent window (8-13μm), thereby lowering the temperature of objects below ambient temperature. This technology has become a cooling strategy attracting considerable attention.

[0003] However, these static radiative coolers only cool objects and continue radiative cooling on cold nights or in winter, leading to undesirable "supercooling" at low temperatures. This exacerbates heating costs, potentially offsetting the energy savings in cooling during hot weather. This single function limits their application in certain scenarios. Therefore, developing a dynamic radiative cooling technology that adapts to changing environmental conditions is crucial.

[0004] Phase change materials (PCMs) are a special class of materials that undergo reversible phase transitions under thermal influence and can store and release large amounts of latent heat within a specified temperature range, exhibiting advantages such as high energy density and small temperature fluctuations. Patent document CN118342857A discloses a thermal shock-resistant composite material coupling phase change heat storage and radiative cooling; liquid Ga has a melting point of 29.8℃, close to room temperature, making it easy to switch between solid and liquid phases with rapid performance changes, and Ga's thermal conductivity is much higher than that of organic PCMs.

[0005] Current inventions combining radiative cooling and phase change energy storage materials mainly involve combining radiative cooling films with organic phase change energy storage materials; however, traditional organic phase change materials have low thermal conductivity and cannot dissipate heat in a timely manner; and they cannot exhibit heating function at low nighttime temperatures. Summary of the Invention

[0006] One of the objectives of this invention is to solve the problems that existing static radiation refrigeration materials cannot change their refrigeration performance at low temperatures, and that organic phase change thermal storage materials have low thermal conductivity.

[0007] The second objective of this invention is to address the problem that existing methods cannot produce composite materials with temperature response, capable of both cooling and heating, and possessing dynamic thermal management capabilities such as daytime heat buffering and nighttime heat release while simultaneously achieving radiative cooling. The invention provides a phase change energy storage-radiative cooling composite material with dynamic thermal management and its preparation method.

[0008] This invention develops temperature-responsive composite materials by preparing Ga-based phase change energy storage materials and coupling them with radiative cooling materials. This promises to achieve dual-function thermal management, including both cooling and heating, significantly enhancing the functionality and application scenarios of existing materials. This invention not only contributes to a deeper understanding of the interaction mechanism between Ga-based phase change energy storage materials and radiative cooling materials but also promotes the development of novel composite materials, opening up new directions for combining phase change thermal storage with radiative cooling.

[0009] A phase change energy storage-radiative cooling composite material with dynamic thermal management exhibits good radiative cooling capacity during the day, with the sample temperature lower than the ambient temperature; it also has good thermal buffering capacity during the day, generating a 12°C temperature difference with the environment upon melting and maintaining it for 1 hour; at night, it has good heat release capacity, releasing stored latent heat upon solidification to raise the temperature to 30°C and maintain it for 1 hour; and it has good thermoelectric power generation potential, generating an output voltage greater than 100mV during the phase change phase and continuously generating an output voltage of 20mV to 40mV during the non-phase change phase.

[0010] A method for preparing a phase change energy storage-radiative cooling composite material with dynamic thermal management is specifically carried out according to the following steps:

[0011] 1. Place liquid metal Ga in an oven for a period of time to obtain fully molten liquid metal Ga;

[0012] 2. Add fully molten liquid Ga metal and metal particles to dilute hydrochloric acid, stir for a period of time, then freeze and solidify, then wash with anhydrous ethanol until neutral, and dry to obtain liquid Ga metal mixed with metal particles.

[0013] 3. Encapsulate liquid Ga with metal particles to obtain Ga-based phase change energy storage material;

[0014] IV. By using thermally conductive double-sided adhesive to combine Ga-based phase change energy storage materials with radiation cooling films, a phase change energy storage-radiation cooling composite material with dynamic thermal management is obtained.

[0015] The principle of this invention:

[0016] This invention combines a radiative cooling film with a phase change energy storage material. Based on the high solar reflectivity and atmospheric window infrared emissivity of the radiative cooling material, it combines the high latent heat of phase change of the phase change energy storage material with the heat release during the solidification process caused by the supercooling of liquid metal Ga, to obtain a composite material that is cooled during the day and heated at night.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] I. The preparation process of this invention is simple and the daytime cooling effect is significant;

[0019] II. The phase change energy storage-radiative cooling composite material with dynamic thermal management prepared by this invention has good thermal buffering capacity during the day. When melting, it can generate a temperature difference of 12°C with the environment and maintain it for 1 hour. At night, it has good heat release capacity. When solidifying, it can release the stored latent heat, raise the temperature to 30°C, and maintain it for 1 hour.

[0020] Third, this invention has good potential for thermoelectric power generation. It can generate an output voltage of more than 100mV during the phase change stage and will continue to generate an output voltage of 20mV to 40mV during the non-phase change stage.

[0021] Fourth, the phase change energy storage-radiative cooling composite material for dynamic thermal management prepared by this invention makes up for the shortcomings of static radiative cooling materials that cannot be dynamically adjusted. Due to the presence of the radiative cooling layer, buildings and people can achieve a cooling effect below room temperature; and due to the presence of the phase change energy storage layer, buildings and people can achieve the effects of daytime heat buffering and nighttime heat release, thereby dynamically regulating the temperature. Attached Figure Description

[0022] Figure 1 The graph shows the comparison of the external field temperature test and cavity environment temperature of the phase change energy storage-radiative cooling composite material with dynamic thermal management prepared in Example 1 and the phase change energy storage material prepared in Comparative Example 1.

[0023] Figure 2 The outdoor thermoelectric power generation performance test diagram is shown for the dynamic thermal management phase change energy storage-radiative cooling composite material prepared in Example 1. Detailed Implementation

[0024] Specific Implementation Method 1: This implementation method describes a phase change energy storage-radiative cooling composite material with dynamic thermal management. It exhibits good radiative cooling capacity during the day, with the sample temperature lower than the ambient temperature. It also has good thermal buffering capacity during the day, generating a 12°C temperature difference with the environment during melting and maintaining it for 1 hour. At night, it has good heat release capacity, releasing stored latent heat during solidification to raise the temperature to 30°C and maintain it for 1 hour. Furthermore, it has good thermoelectric power generation potential, generating an output voltage greater than 100mV during the phase change stage and continuously generating an output voltage of 20mV to 40mV during the non-phase change stage.

[0025] Specific Implementation Method Two: This implementation method is a preparation method of a dynamic thermal management phase change energy storage-radiative cooling composite material, specifically completed according to the following steps:

[0026] 1. Place liquid metal Ga in an oven for a period of time to obtain fully molten liquid metal Ga;

[0027] 2. Add fully molten liquid Ga metal and metal particles to dilute hydrochloric acid, stir for a period of time, then freeze and solidify, then wash with anhydrous ethanol until neutral, and dry to obtain liquid Ga metal mixed with metal particles.

[0028] 3. Encapsulate liquid Ga with metal particles to obtain Ga-based phase change energy storage material;

[0029] IV. By using thermally conductive double-sided adhesive to combine Ga-based phase change energy storage materials with radiation cooling films, a phase change energy storage-radiation cooling composite material with dynamic thermal management is obtained.

[0030] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the temperature of the oven in step one is 50℃~70℃; and the time for placing the liquid metal Ga in the oven in step one is 1h~2h. Other steps are the same as in Specific Implementation Method One or Two.

[0031] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in the following ways: the concentration of the dilute hydrochloric acid in step two is 0.15 mol / L to 0.25 mol / L; the total mass ratio of the fully molten liquid Ga metal and metal particles to the volume of the dilute hydrochloric acid in step two is (10 g to 15 g): 50 mL; and the stirring time in step two is 2 min to 5 min. Other steps are the same as in Specific Implementation Methods One to Three.

[0032] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in the following ways: the freezing temperature in step two is -15℃ to -10℃, and the freezing time is 0.5h to 1h; the drying temperature in step two is 50℃ to 70℃, and the drying time is 1h to 3h; the metal particles in step two are copper particles; the particle size of the copper particles is 60μm to 80μm; the mass fraction of the metal particles in the liquid Ga metal after incorporating the metal particles in step two is 1% to 10%. Other steps are the same as in Specific Implementation Methods One to Four.

[0033] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step three, a polymer film is used to encapsulate the liquid metal Ga doped with metal particles; the polymer film is a PE film. The other steps are the same as in Specific Implementation Methods One to Five.

[0034] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the thickness of the polymer film described in step three is 0.06 mm to 0.1 mm; the thickness of the Ga-based phase change energy storage material described in step three is 3 mm to 5 mm. The other steps are the same as in Specific Implementation Methods One to Six.

[0035] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One through Seven in that: in step four, thermally conductive double-sided adhesive is used to combine the Ga-based phase change energy storage material with the radiation-cooling film. Specifically, the Ga-based phase change energy storage material is attached to one side of the thermally conductive double-sided adhesive, and the radiation-cooling film is attached to the other side of the thermally conductive double-sided adhesive. The other steps are the same as in Specific Implementation Methods One through Seven.

[0036] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the radiation-cooling film mentioned in step four is a TPU nanofiber film, which is prepared by electrospinning using TPU solution as raw material. The other steps are the same as in Specific Implementation Methods One to Eight.

[0037] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the preparation method of the TPU nanofiber membrane is specifically carried out according to the following steps: TPU is added to N,N-dimethylformamide and magnetically stirred at 40℃~50℃ for 10h~12h to obtain a TPU solution with a mass fraction of 15%~20%; the 15%~20% TPU solution is added to a 5mL disposable syringe with a NO.22 metal needle attached, and spinning is performed at a receiving distance of 20cm and a pushing speed of 2mm / min under the conditions of ambient temperature of 40℃ and relative humidity of 25%; then, it is vacuum dried at 70℃ for 12h to obtain a TPU nanofiber membrane; the thickness of the TPU nanofiber membrane is 0.2mm~0.4mm. Other steps are the same as in Specific Implementation Methods One to Nine.

[0038] The beneficial effects of the present invention are verified using the following embodiments:

[0039] Example 1: A method for preparing a phase change energy storage-radiative cooling composite material with dynamic thermal management, specifically completed according to the following steps:

[0040] 1. Place liquid metal Ga in an oven at 60°C for 1 hour to obtain fully molten liquid metal Ga;

[0041] 2. The fully molten liquid metal Ga and metal particles are added to dilute hydrochloric acid with a concentration of 0.2 mol / L, stirred for 2 min, then frozen solidified at -15℃ for 0.5 h, washed with anhydrous ethanol until neutral, and dried in an oven at 60℃ for 1 h to obtain liquid metal Ga with metal particles incorporated.

[0042] The total mass ratio of the fully molten liquid metal Ga and metal particles to the volume of dilute hydrochloric acid in step two is 12.6 g: 50 mL.

[0043] The metal particles mentioned in step two are copper particles; the particle size of the copper particles is 70 μm.

[0044] In step two, the mass fraction of metal particles in the liquid Ga after incorporation is 5%.

[0045] 3. Liquid metal Ga doped with metal particles was encapsulated in a PE film with a thickness of 0.08 mm to obtain Ga-based phase change energy storage material.

[0046] The thickness of the Ga-based phase change energy storage material mentioned in step three is 4 mm;

[0047] IV. A Ga-based phase change energy storage material is attached to one side of the thermally conductive double-sided adhesive, and a radiation cooling film is attached to the other side of the thermally conductive double-sided adhesive to obtain a phase change energy storage-radiation cooling composite material with dynamic thermal management.

[0048] The radiation cooling film mentioned in step four is a TPU nanofiber film, which is prepared by electrospinning using TPU solution as raw material.

[0049] The preparation method of the TPU nanofiber membrane is specifically carried out according to the following steps: TPU (thermoplastic polyurethane) is added to N,N-dimethylformamide (DMF) and magnetically stirred at 40°C for 12 hours to obtain a TPU solution with a mass fraction of 18%; the 18% TPU solution is added to a 5mL disposable syringe with a NO.22 metal needle attached, and spinning is performed at an ambient temperature of 40°C and a relative humidity of 25%, maintaining a receiving distance of 20cm and a pushing speed of 2mm / min; then, it is vacuum dried at 70°C for 12 hours to obtain the TPU nanofiber membrane; the thickness of the TPU nanofiber membrane is 0.3mm.

[0050] Comparative Example 1: A method for preparing a phase change energy storage material, specifically comprising the following steps:

[0051] 1. Place liquid metal Ga in an oven at 60°C for 1 hour to obtain fully molten liquid metal Ga;

[0052] 2. A phase change energy storage material is obtained by encapsulating fully molten liquid Ga with a PE film with a thickness of 0.08 mm.

[0053] Figure 1 The graph shows the comparison of the external field temperature test and cavity environment temperature of the phase change energy storage-radiative cooling composite material with dynamic thermal management prepared in Example 1 and the phase change energy storage material prepared in Comparative Example 1.

[0054] from Figure 1 It can be seen that the dynamic thermal management phase change energy storage-radiative cooling composite material prepared in Example 1 has a daytime temperature lower than the ambient temperature, while the phase change energy storage material prepared in Comparative Example 1 has a temperature higher than the ambient temperature. Furthermore, the dynamic thermal management phase change energy storage-radiative cooling composite material prepared in Example 1 exhibits good dynamic thermal management performance. When melting, it can generate a temperature difference of about 12°C with the environment and maintain it for about 1 hour. It has good heat release capacity at night. When solidifying, it can release the stored latent heat, raise the temperature to 30°C and maintain it for about 1 hour.

[0055] Figure 2 The outdoor thermoelectric power generation performance test diagram of the dynamic thermal management phase change energy storage-radiative cooling composite material prepared in Example 1;

[0056] from Figure 2 It can be seen that the dynamic thermal management phase change energy storage-radiative cooling composite material prepared in Example 1 can generate a large temperature difference between the two ends of the thermoelectric generator during the phase change stage, and can generate an output voltage greater than 100mV; and will also continuously generate an output voltage of 20mV to 40mV during the non-phase change stage.

Claims

1. A method for preparing a phase change energy storage-radiative cooling composite material with dynamic thermal management, characterized in that... The preparation method is specifically carried out according to the following steps:

1. Place liquid metal Ga in an oven at 60°C for 1 hour to obtain fully molten liquid metal Ga; 2. The fully molten liquid metal Ga and metal particles are added to dilute hydrochloric acid with a concentration of 0.2 mol / L, stirred for 2 min, then frozen and solidified at -15℃ for 0.5 h, then washed with anhydrous ethanol until neutral, and dried in an oven at 60℃ for 1 h to obtain liquid metal Ga with metal particles incorporated. The total mass ratio of the fully molten liquid metal Ga and metal particles to the volume of dilute hydrochloric acid in step two is 12.6 g: 50 mL. The metal particles mentioned in step two are copper particles; the particle size of the copper particles is 70 μm. In step two, the mass fraction of metal particles in the liquid Ga metal after incorporation is 5%.

3. Liquid metal Ga doped with metal particles was encapsulated in a PE film with a thickness of 0.08 mm to obtain Ga-based phase change energy storage material. The thickness of the Ga-based phase change energy storage material mentioned in step three is 4 mm; IV. A Ga-based phase change energy storage material is attached to one side of the thermally conductive double-sided adhesive, and a radiation cooling film is attached to the other side of the thermally conductive double-sided adhesive to obtain a phase change energy storage-radiation cooling composite material with dynamic thermal management. The radiation cooling film mentioned in step four is a TPU nanofiber film.

2. The preparation method of a phase change energy storage-radiative cooling composite material with dynamic thermal management according to claim 1, characterized in that... The preparation method of the TPU nanofiber membrane is specifically carried out according to the following steps: TPU (thermoplastic polyurethane) is added to N,N-dimethylformamide (DMF) and magnetically stirred at 40°C for 12 hours to obtain a TPU solution with a mass fraction of 18%; the 18% TPU solution is added to a 5mL disposable syringe with a NO.22 metal needle attached, and spinning is performed at an ambient temperature of 40°C and a relative humidity of 25%, maintaining a receiving distance of 20cm and a pushing speed of 2mm / min; then, it is vacuum dried at 70°C for 12 hours to obtain the TPU nanofiber membrane; the thickness of the TPU nanofiber membrane is 0.3mm.

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