Radiation refrigeration structure based on phase change material

Abstract

The invention provides a radiation refrigeration structure based on a phase change material, and belongs to the technical field of radiation refrigeration devices. The radiation refrigeration structure is composed of an optical window structure and a phase change radiation control structure; the optical window structure is formed by alternately stacking metal layers and dielectric layers; the optical window structure is fixed to the side face of the heat insulation support, and the phase-change radiation control structure is tightly connected with the refrigerated material, fixed to the bottom face of the heat insulation support and spaced from the optical window structure by a certain distance. Through the combined action of the dielectric layer and the metal layer, the heat radiated by the radiation refrigeration material is radiated out through the wave band in the atmosphere window wave band, and the refrigeration effect is achieved; the phase change radiation control structure sequentially comprises a phase change layer, a dielectric layer and a reflecting layer; the phase change layer changes optical properties according to temperature changes to achieve dynamic refrigeration effect regulation and control, and the reflecting layer is tightly attached to a refrigerated material to rapidly conduct heat.

Description

Technical Field

[0001] The present invention belongs to the technical field of radiation cooling devices, and in particular, relates to a radiation cooling structure based on phase change materials. Background Art

[0002] Radiative cooling, as a passive cooling method that uses the heat radiation of an object to exchange energy with the universe, has great potential. Radiative cooling devices use the radiative heat exchange between an object and its surroundings to reduce the temperature of the object. The refrigeration material radiates from the device to the outside with a wavelength in the atmospheric window band (such as Figure 5 In the middle blue shaded area, electromagnetic waves of 8μm-13μm) achieve the cooling effect, while blocking the external radiation into the device, while allowing the radiation of the cooling material to be emitted outward as much as possible.

[0003] In the process of pursuing the improvement of cooling efficiency, existing radiant cooling devices often ignore the effective regulation of the device's operating status. Under different environmental conditions and work requirements, the lack of a dynamic regulation mechanism makes it impossible for radiant cooling devices to flexibly adapt to changes, which in turn affects their overall performance and energy efficiency. For example, in some areas with large temperature differences between day and night, traditional radiant cooling devices cannot automatically adjust the cooling mode according to temperature changes. They may continue to perform high-intensity cooling when the temperature is lower at night, which not only causes energy waste, but may also affect the service life of the device.

[0004] Existing radiative cooling technology has certain limitations in optical window design. Optical windows are crucial for radiative cooling devices, and their performance directly affects the working efficiency of the device. However, most current optical window designs only focus on improving the radiation transmittance of the atmospheric window band, and fail to fully consider the effective control of radiation in other bands (such as solar radiation). Solar radiation is very intense during the day. If it cannot be effectively blocked, it will bring a large amount of unnecessary heat input to the refrigeration device, seriously interfering with the refrigeration effect, and may even make the refrigeration device unable to work normally during the day, greatly limiting the all-weather application capability of radiative cooling technology. Summary of the invention

[0005] In summary, in order to solve the technical defects of the existing radiation cooling devices in terms of lack of dynamic adaptive regulation and optimization design, the present invention designs a radiation cooling structure based on phase change materials, which can achieve effective blocking of solar radiation and high emissivity of atmospheric window band radiation, improve the performance stability and energy utilization efficiency of the radiation cooling device, and provide strong support for the promotion of radiation cooling technology in practical applications.

[0006] A radiation cooling structure based on phase change material, characterized by:

[0007] The radiation cooling structure consists of an optical window structure and a phase-change radiation control structure;

[0008] The optical window structure is formed by alternately stacking metal layers and dielectric layers;

[0009] The bottom and top layers are both metal layers, which protect the internal dielectric layer while blocking solar radiation through their own optical properties;

[0010] The optical window structure is fixed on the side of the thermal insulation bracket; the dielectric layer and the metal layer work together to allow the heat radiated by the refrigeration material to be dissipated through the atmospheric window band, thereby achieving a refrigeration effect;

[0011] The phase change radiation control structure is composed of a phase change layer, a dielectric layer and a reflective layer in sequence; the phase change layer changes its optical properties according to temperature changes to achieve dynamic temperature control, and the reflective layer is in close contact with the refrigerated material to quickly conduct heat. The refrigerated material is fixed on the bottom surface of the insulation bracket; and there is a certain distance between it and the optical window structure.

[0012] Furthermore, the metal layer is made of Ge, which uses its high blocking rate for solar radiation to reduce the entry of external radiation.

[0013] Furthermore, the dielectric layer is made of BaF2, which utilizes its transmittance to the atmospheric window and is combined with Ge to enable the radiation cooling structure to have a high transmittance in the range of 8 to 13 μm.

[0014] Furthermore, the material of the phase change layer is VO2.

[0015] When T>300K, VO2 is in a metallic state. At this time, the phase change radiation control structure is in the radiation cooling on state. The heat of the cooled material is radiated to space through the optical window structure, and the temperature gradually decreases.

[0016] When T<300K, VO2 is in an insulating state. At this time, the phase change radiation control structure is in a radiation cooling closed state. The cooled material radiates almost no heat to the outside world, but will accept the energy radiated from the outside world, and the temperature gradually rises.

[0017] Furthermore, the reflective layer is made of Ag, which has extremely high reflectivity in the visible light and near-infrared bands, and can effectively reflect electromagnetic waves and reduce the absorption and transmission of light.

[0018] Furthermore, the thickness of each layer of the radiation cooling structure is obtained by simulation using a finite difference time domain method;

[0019] The temperature field distribution of the refrigerated material (3) can be solved by the radiation and heat conduction transmission equations:

[0020]

[0021] In the formula, Λ is the thermal conductivity, T(x) is the temperature at point x, and q r is the radiation heat flux, σ B is the Stefan-Boltzmann constant, I(x,Ω) is the radiation intensity along the direction Ω at coordinate x, n is the direction vector, β, α and σ are the attenuation, absorption and scattering coefficients respectively, and Φ(Ω,Ω′) is the scattering phase function.

[0022] Furthermore, the optical window structure has 11 layers in total, and the thickness of each layer is different;

[0023] The first layer is Ge, 240nm thick; the second layer is BaF2, 410nm thick;

[0024] The third layer is Ge, 530nm thick; the fourth layer is BaF2, 130nm thick;

[0025] The fifth layer is Ge, 190nm thick; the sixth layer is BaF2, 1160nm thick;

[0026] The 7th layer is Ge, 160nm thick; the 8th layer is BaF2, 1020nm thick;

[0027] The 9th layer is Ge, 610nm thick; the 10th layer is BaF2, 450nm thick;

[0028] The 11th layer is Ge, 270nm thick;

[0029] The phase-change radiation control structure has three layers, and the thickness of each layer is different;

[0030] The first layer is VO2, 30nm thick;

[0031] The second layer is BaF2, 1800nm ​​thick;

[0032] The third layer is Ag, with a thickness of 1000nm.

[0033] A method for preparing a radiation cooling structure based on phase change materials:

[0034] The preparation method is a magnetron sputtering method;

[0035] First, an optical window structure is prepared, the chamber of a magnetron sputtering device is evacuated to a vacuum state, and Ge and BaF2 are installed on the sputtering cathode; argon gas is injected into the chamber as a sputtering gas, and appropriate sputtering power and sputtering time are set, and Ge and BaF2 materials are first alternately deposited on a substrate by a deposition method to form an optical window structure in which the metal layer and the dielectric layer are alternately stacked;

[0036] Then, a phase-change radiation control structure is prepared, the chamber of the magnetron sputtering device is evacuated to a vacuum state, BaF2, VO2 and Ag targets are installed on the sputtering cathode, VO2, BaF2 and Ag materials are deposited in sequence to form the phase-change radiation control structure in which the phase-change layer, the dielectric layer and the reflective layer are stacked in sequence;

[0037] Finally, the optical window structure is fixed on the side of the insulation bracket, the phase change radiation control structure is closely connected to the refrigerated material and is placed at a certain distance from the optical window structure, and the refrigerated material is fixed on the bottom surface of the insulation bracket to form the radiation refrigeration structure based on phase change material.

[0038] An electronic device comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0039] A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the steps of the above method are implemented.

[0040] Beneficial effects of the present invention:

[0041] The refrigeration effect of the present invention is better: by designing an 11+3-layer film structure, Ge and BaF2 are combined and stacked at a specific thickness, high transmittance to the atmospheric window band (8-13μm) and effective blocking of non-target bands are achieved; compared with the single material or simple laminated structure commonly used in existing radiation refrigeration devices, the multi-layer film structure of the present invention optimizes the radiation efficiency and significantly reduces heat loss, making the refrigeration effect more stable.

[0042] The present invention has dynamic regulation capability: by using phase change material VO2 as the core material, using its reversible characteristics of the metallic state and the insulating state at the critical temperature (300K) to realize a function similar to a switch, the refrigeration (yes / no) mode can be actively switched according to the temperature change, ensuring that when it is below 300K, almost no energy is radiated outwards and external radiation is received to increase the temperature. When it is above 300K, the heat of the refrigerated material is radiated to space through the optical window structure, and the temperature gradually decreases. The above method effectively solves the problem that traditional radiation refrigeration devices lack dynamic regulation capability.

[0043] The multilayer composite structure of the present invention has higher flexibility in thermal regulation capability: by using a combination of BaF2 and Ag, the light transmittance and reflectivity characteristics of the material are enhanced in the temperature regulation function, so that the device maintains a low emissivity at high temperatures, thereby further optimizing the thermal management performance of the refrigeration device.

[0044] The present invention establishes a basic model through the finite-difference time-domain method and multiple simulation optimizations, and makes adjustments in materials and layer thicknesses to ensure consistency in high transmittance and radiation cooling performance at various angles and temperatures.

[0045] The radiation cooling structure of the present invention can achieve the effect of lowering the temperature of physical state change and thus changing the switching temperature by adding other materials to the VO2 layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is an overall schematic diagram of the radiation cooling structure of the present invention;

[0047] Figure 2 It is a schematic diagram of the optical window structure of the upper part of the radiation cooling structure of the present invention;

[0048] Figure 3 It is a schematic diagram of the phase change radiation control structure of the lower part of the radiation cooling structure of the present invention;

[0049] Figure 4 It is a schematic diagram of the working principle of the radiation cooling structure of the present invention;

[0050] Figure 5 Schematic diagram of the emissivity of the radiative cooling structure in the 0.3-15μm band;

[0051] Figure 6 This is the relationship between the average emissivity of the radiation cooling structure and the polarization direction and emission angle;

[0052] Figure 7 This is the relationship between the net cooling power of the radiation cooling structure and the structure temperature;

[0053] Among them, 1 is an optical window structure; 2 is a phase change radiation control structure; 3 is a refrigerated material; 4 is a side surface of a thermal insulation bracket; 5 is a bottom surface of a thermal insulation bracket; 6 is a metal layer; 7 is a dielectric layer; 8 is a phase change layer; 9 is a reflective layer; DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0056] Combination Figures 1 to 7 The present invention proposes a radiation refrigeration structure based on phase change materials, which regulates the heat radiation transmission in the radiation refrigeration process and improves the performance of the entire radiation refrigeration device by optimizing the transmission path of heat radiation.

[0057] While ensuring that the electromagnetic waves radiated by the radiation cooling material can be dissipated into the external environment through the atmospheric window band, other unnecessary radiation from the outside, such as solar radiation, is blocked as much as possible from entering the refrigeration device.

[0058] A radiation cooling structure based on phase change materials:

[0059] The radiation cooling structure is composed of an optical window structure 1 and a phase-change radiation control structure 22;

[0060] The optical window structure is formed by alternately stacking metal layers 6 and dielectric layers 7;

[0061] The bottom and top layers are both metal layers 6, which protect the internal dielectric layer 7 while blocking solar radiation through their own optical properties;

[0062] The optical window structure 1 is fixed to the side surface 4 of the heat-insulating bracket; the dielectric layer 7 and the metal layer 6 work together to allow the heat radiated by the refrigeration material 3 to be dissipated through the atmospheric window band, thereby achieving a refrigeration effect;

[0063] The phase change radiation control structure 2 is composed of a phase change layer 8, a dielectric layer 7 and a reflective layer 9 in sequence; the phase change layer 8 changes its optical properties according to temperature changes to achieve dynamic temperature control, and the reflective layer 9 is in close contact with the cooled material 3 to quickly conduct heat. The cooled material 3 is fixed on the bottom surface 5 of the insulation bracket; and there is a certain distance (>5 cm) between it and the optical window structure 1.

[0064] The metal layer 6 is made of Ge, which uses its high blocking rate for solar radiation to reduce the entry of external radiation.

[0065] The dielectric layer 7 is made of BaF2, which utilizes its transmittance to the atmospheric window and is combined with Ge to enable the radiation cooling structure to have a high transmittance in the range of 8 to 13 μm.

[0066] The material of the phase change layer 8 is VO2.

[0067] When T>300K, VO2 is in a metallic state. At this time, the phase change radiation control structure is in the radiation cooling on state. The heat of the cooled material is radiated to space through the optical window structure, and the temperature gradually decreases.

[0068] When T<300K, VO2 is in an insulating state. At this time, the phase change radiation control structure is in a radiation cooling closed state. The cooled material radiates almost no heat to the outside world, but will accept the energy radiated from the outside world, and the temperature gradually rises.

[0069] The reflective layer 9 is made of Ag, which has extremely high reflectivity in the visible light and near-infrared bands, and can effectively reflect electromagnetic waves and reduce the absorption and transmission of light.

[0070] The thickness of each layer of the radiation cooling structure is obtained by simulation using the finite difference time domain method;

[0071] The temperature field distribution of the refrigerated material (3) can be solved by the radiation and heat conduction transmission equations:

[0072]

[0073] In the formula, Λ is the thermal conductivity, T(x) is the temperature at point x, and q r is the radiation heat flux, σ B is the Stefan-Boltzmann constant, I(x,Ω) is the radiation intensity along the direction Ω at coordinate x, n is the direction vector, β, α and σ are the attenuation, absorption and scattering coefficients respectively, and Φ(Ω,Ω′) is the scattering phase function.

[0074] The optical window structure 1 has 11 layers in total, and the thickness of each layer is different;

[0075] The first layer is Ge, 240nm thick; the second layer is BaF2, 410nm thick;

[0076] The third layer is Ge, 530nm thick; the fourth layer is BaF2, 130nm thick;

[0077] The fifth layer is Ge, 190nm thick; the sixth layer is BaF2, 1160nm thick;

[0078] The 7th layer is Ge, 160nm thick; the 8th layer is BaF2, 1020nm thick;

[0079] The 9th layer is Ge, 610nm thick; the 10th layer is BaF2, 450nm thick;

[0080] The 11th layer is Ge, 270nm thick;

[0081] The phase-change radiation control structure 2 has three layers, and the thickness of each layer is different;

[0082] The first layer is VO2, 30nm thick;

[0083] The second layer is BaF2, 1800nm ​​thick;

[0084] The third layer is Ag with a thickness of 1000 nm.

[0085] A preparation method of a radiation cooling structure based on a phase change material:

[0086] The preparation method is a magnetron sputtering method;

[0087] First, prepare the optical window structure 1. Pump the chamber of the magnetron sputtering device to a vacuum state. Install Ge and BaF2 on the sputtering cathode. Charge argon gas into the chamber as the sputtering gas. Set appropriate sputtering power and sputtering time. First, alternately deposit Ge and BaF2 materials on the substrate by the deposition method to form the optical window structure 1 with the metal layer 6 and the dielectric layer 7 stacked alternately;

[0088] Then, prepare the phase change radiation control structure 2. Pump the chamber of the magnetron sputtering device to a vacuum state. Install BaF2, VO2, and Ag targets on the sputtering cathode. Deposit VO2, BaF2, and Ag materials in sequence to form the phase change radiation control structure 2 with the phase change layer 8, the dielectric layer 7, and the reflection layer 9 stacked in sequence;

[0089] Finally, fix the optical window structure 1 on the side 4 of the heat insulation bracket. The phase change radiation control structure 2 is closely connected to the material to be cooled 3 and is placed at a certain interval (>5 cm) from the optical window structure 1. The material to be cooled 3 is fixed on the bottom surface 5 of the heat insulation bracket to form the radiation cooling structure based on the phase change material.

[0090] As Figure 4 is a schematic diagram of the working principle of the radiation cooling structure. Ideally, it is required that when the radiation cooling mode is closed (T < Tc), the structure hardly radiates energy to the outside world; when the radiation cooling mode is turned on, the structure radiates energy to the outside through the optical window in the atmospheric window band, so as to realize that above the temperature of 300K, the radiation cooling mode is turned on, and below it, the radiation cooling mode is turned off.

[0091] As Figure 5 , the blue shaded part is the atmospheric window band, that is, the required band; the blue thin line is the emissivity of the radiation cooling structure in the corresponding band when the cooling mode is turned on, and the red thin line is the emissivity of the radiation cooling structure in the corresponding band when the cooling mode is turned off. When the switch is turned on, for the required band, the average emissivity of the device in the target band exceeds 90%; for the unwanted band, the reflectivity of this window structure also reaches a good data. When the switch is turned on, the emissivity of the structure is less than 10%.

[0092] As Figure 6, in the design process of this structure, the change of the average emissivity caused by the different angles between the outward radiation and the window is fully considered, making the data more sufficient and reference-worthy. TM and TE are two forms of electromagnetic waves: the former is the transverse magnetic wave, and the latter is the transverse electric wave. Among them, the blue and red thin lines are the average emissivities of the device at various angles when T > Tc; the green and pink thin lines are the average emissivities of the device at various angles when T < Tc. Separated plotting can more intuitively show that when this switch structure is turned on, both the transverse magnetic wave and the transverse electric wave have relatively high emissivities (higher than 60%) from 0° to 60°, and the average transmittance of electromagnetic waves from 0° to 70° is still higher than 60%. When it is turned off, both the transverse magnetic wave and the transverse electric wave have extremely low emissivities at all angles.

[0093] Such as Figure 7 , when the temperature is lower than the critical temperature (orange broken line), the refrigeration power of this device increases with the increase of temperature, rising from nearly -150 W / m at 280 K 2 to nearly 0 W / m at 300 K 2 . When the temperature is higher than the critical temperature (blue broken line), the refrigeration power of this device increases with the increase of temperature, rising from nearly 0 W / m at 300 K 2 to nearly 200 W / m at 320 K 2 . Generally speaking, this structure realizes the switching of the refrigeration mode of the material at the critical temperature (300 K), making the net refrigeration power negative below the critical temperature and positive above the critical temperature.

[0094] An electronic device includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the above method are implemented.

[0095] A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the steps of the above method are implemented.

[0096] The memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory, ROM, a programmable read-only memory, PROM, an erasable programmable read-only memory, EPROM, an electrically erasable programmable read-only memory, EEPROM, or a flash memory. The volatile memory may be a random access memory, RAM, which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory static RAM, SRAM, dynamic random access memory dynamic RAM, DRAM, synchronous dynamic random access memory synchronous DRAM, SDRAM, double data rate synchronous dynamic random access memory double data rate SDRAM, DDR SDRAM, enhanced synchronous dynamic random access memory enhanced SDRAM, ESDRAM, synchronous link dynamic random access memory synchlink DRAM, SLDRAM, and direct memory bus random access memory direct rambus RAM, DR RAM. It should be noted that memory of the methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0097] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, computer, server or data center through a wired method such as coaxial cable, optical fiber, digital subscriber line digital subscriber line, DSL or wireless such as infrared, wireless, microwave, etc. to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that includes one or more available media integrated. The available medium can be a magnetic medium such as a floppy disk, a hard disk, a tape, an optical medium such as a high-density digital video disc digital video disc, DVD, or a semiconductor medium such as a solid state hard disk solid state disc, SSD, etc.

[0098] In the implementation process, each step of the above method can be completed by an integrated logic circuit of hardware in a processor or an instruction in the form of software. The steps of the method disclosed in conjunction with the embodiment of the present application can be directly embodied as a hardware processor for execution, or a combination of hardware and software modules in a processor for execution. The software module can be located in a storage medium mature in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in conjunction with its hardware. To avoid repetition, it is not described in detail here.

[0099] It should be noted that the processor in the embodiment of the present application can be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method embodiment can be completed by an integrated logic circuit of hardware in the processor or an instruction in the form of software. The above processor can be a general-purpose processor, a digital signal processor DSP, an application-specific integrated circuit ASIC, a field programmable gate array FPGA or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiment of the present application can be directly embodied as a hardware decoding processor to perform, or the hardware and software modules in the decoding processor can be combined to perform. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0100] The above is a detailed introduction to a radiation cooling structure based on phase change material proposed in the present invention, and the principles and implementation methods of the present invention are explained. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A radiation cooling structure based on phase change material, characterized in that: The radiation cooling structure is composed of an optical window structure (1) and a phase-change radiation control structure (2); The optical window structure (1) is formed by alternately stacking metal layers (6) and dielectric layers (7); The bottom layer and the top layer are both metal layers (6), which protect the internal dielectric layer (7) and block solar radiation through their own optical properties; The optical window structure (1) is fixed on the side surface (4) of the heat-insulating support; the dielectric layer (7) and the metal layer (6) work together to allow the heat radiated by the refrigeration material (3) to be dissipated through the atmospheric window band, thereby achieving a refrigeration effect; The phase-change radiation control structure (2) comprises a phase-change layer (8), a dielectric layer (7) and a reflective layer (9) in sequence; the phase-change layer (8) changes its optical properties according to temperature changes to achieve dynamic temperature control; the reflective layer (9) is in close contact with the refrigerated material (3) to quickly conduct heat; the refrigerated material (3) is fixed on the bottom surface (5) of the thermal insulation bracket; and there is a certain distance between the refrigerated material (3) and the optical window structure (1).

2. The radiant cooling structure according to claim 1, characterized in that: The material of the metal layer (6) is Ge, and its high blocking rate for solar radiation is utilized to reduce the entry of external radiation.

3. The radiant cooling structure according to claim 2, characterized in that: The dielectric layer (7) is made of BaF2, which utilizes its transmittance to the atmospheric window and is combined with Ge to enable the radiation cooling structure to have a high transmittance in the range of 8 to 13 μm.

4. The radiant cooling structure according to claim 3, characterized in that: The material of the phase change layer (8) is VO2, When T>300K, VO2 is in a metallic state. At this time, the phase change radiation control structure (2) is in a radiation cooling on state. The heat of the refrigerated material (3) is radiated into space through the optical window structure (1), and the temperature gradually decreases. When T<300K, VO2 is in an insulating state. At this time, the phase change radiation control structure (2) is in a radiation cooling closed state. The cooled material (3) hardly radiates heat to the outside world, but will receive energy radiated from the outside world, and the temperature gradually rises.

5. The radiant cooling structure according to claim 4, characterized in that: The reflective layer (9) is made of Ag, which has extremely high reflectivity in the visible light and near-infrared bands, and can effectively reflect electromagnetic waves and reduce the absorption and transmission of light.

6. The radiant cooling structure according to claim 5, characterized in that: The optical characteristics of the radiation cooling structure are simulated by the finite difference time domain method. The temperature field distribution of the refrigerated material (3) can be solved by the radiation and heat conduction transmission equations: In the formula, Λ is the thermal conductivity, T(x) is the temperature at point x, and q r is the radiation heat flux, σ B is the Stefan-Boltzmann constant, I(x,Ω) is the radiation intensity along the direction Ω at coordinate x, n is the direction vector, β, α and σ are the attenuation, absorption and scattering coefficients respectively, and Φ(Ω,Ω′) is the scattering phase function.

7. The radiant cooling structure according to claim 6, characterized in that: The optical window structure (1) has 11 layers in total, and the thickness of each layer is different; The first layer is Ge, 240nm thick; the second layer is BaF2, 410nm thick; The third layer is Ge, 530nm thick; the fourth layer is BaF2, 130nm thick; The fifth layer is Ge, 190nm thick; the sixth layer is BaF2, 1160nm thick; The 7th layer is Ge, 160nm thick; the 8th layer is BaF2, 1020nm thick; The 9th layer is Ge, 610nm thick; the 10th layer is BaF2, 450nm thick; The 11th layer is Ge, 270nm thick; The phase-change radiation control structure (2) has three layers in total, and the thickness of each layer is different; The first layer is VO2, 30nm thick; The second layer is BaF2, 1800nm ​​thick; The third layer is Ag, with a thickness of 1000nm.

8. A method for preparing a radiation cooling structure based on a phase change material according to any one of claims 1 to 7, characterized in that: The preparation method is a magnetron sputtering method; First, an optical window structure (1) is prepared, the chamber of a magnetron sputtering device is evacuated to a vacuum state, and Ge and BaF2 are installed on the sputtering cathode; argon gas is injected into the chamber as a sputtering gas, and appropriate sputtering power and sputtering time are set, and Ge and BaF2 materials are first deposited alternately on a substrate by a deposition method to form an optical window structure (1) in which the metal layer (6) and the dielectric layer (7) are alternately stacked; Then, a phase-change radiation control structure (2) is prepared, the chamber of the magnetron sputtering device is evacuated to a vacuum state, BaF2, VO2 and Ag targets are installed on the sputtering cathode, VO2, BaF2 and Ag materials are deposited in sequence to form the phase-change radiation control structure (2) by stacking the phase-change layer (8), the dielectric layer (7) and the reflective layer (9) in sequence; Finally, the optical window structure (1) is fixed on the side surface (4) of the thermal insulation bracket, the phase change radiation control structure (2) is closely connected to the refrigerated material (3) and is placed at a certain distance from the optical window structure (1), and the refrigerated material (3) is fixed on the bottom surface (5) of the thermal insulation bracket, thereby forming the radiation refrigeration structure based on phase change material.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method according to claim 8 when executing the computer program.

10. A computer-readable storage medium for storing computer instructions, wherein the computer instructions implement the steps of the method of claim 8 when executed by a processor.

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