Optical window structure for radiation refrigeration

Abstract

The invention provides an optical window structure for radiation refrigeration, and belongs to the technical field of radiation refrigeration devices, and the structure of the optical window is formed by alternately stacking metal layers and dielectric layers; the lowermost layer and the uppermost layer are metal layers, so that the internal dielectric layer is protected, meanwhile, solar radiation is blocked through the optical characteristics of the radiation refrigeration material, and it is ensured that the radiation refrigeration material is in a relatively low-temperature environment; 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 metal layer is made of Ge, and external radiation entering is reduced by means of the high blocking rate of the metal layer on sunlight band radiation; the material of the dielectric layer is BaF2, and the transmission rate of the dielectric layer to an atmospheric window is utilized, and the dielectric layer is combined with Ge, so that the optical window structure has high transmission rate in the range of 8-13 microns.

Description

Technical Field

[0001] The present invention belongs to the technical field of radiation cooling devices, and in particular, relates to an optical window structure for radiation cooling. Background Art

[0002] With the continuous growth of global demand for energy and the increasingly prominent environmental problems, finding efficient, energy-saving and environmentally friendly refrigeration technology has become a research hotspot.

[0003] As a passive cooling method that uses the thermal radiation of objects to exchange energy with the universe, radiative cooling has great potential. Radiative cooling devices dissipate heat to space through the atmospheric window. The refrigeration material radiates from the device to the outside with a wavelength in the atmospheric window band (such as Figure 2 In the middle blue vertical line part, electromagnetic waves of 8-13μm) achieve a cooling effect, while blocking external radiation into the device, the radiation of the cooling material is emitted outward as much as possible, that is, the transmittance of the window structure in this band is improved.

[0004] In actual environments, the power of solar radiation varies greatly and is strong during the day. If the solar radiation cannot be effectively blocked from entering the refrigeration device, a large amount of heat will be input, which will seriously restrict the performance of radiative cooling. At the same time, the absorption of solar radiation will significantly reduce the cooling efficiency of the radiator, and may even completely lose the cooling effect.

[0005] For radiative cooling devices, the performance of the optical window will play a crucial role in the overall performance of the device. If the optical window design is unreasonable, the performance of the device will not meet the expected standards, thereby reducing work efficiency. The radiation transmittance of the optical window to a specific band will determine the working efficiency of the device. Therefore, in the design process of the optical window, the reasonable selection of parameters is related to whether the radiative cooling device is qualified or not.

[0006] However, the existing technology still faces some problems in practical applications, including but not limited to: the optical window design of existing radiation cooling devices is often insufficient, and most traditional radiation cooling optical windows only focus on increasing the radiation transmittance of the atmospheric window, but ignore the key impact of blocking solar band radiation on achieving all-weather cooling.

[0007] If the material type is not properly selected, it will result in (1) low transmittance of the window in the required band, reducing the working efficiency of the radiation cooling device; (2) inappropriate transmittance range will reduce the window filtering efficiency (a range less than 8-13μm will reduce the emission efficiency; a range greater than 8-13μm will cause more external radiation to enter the device, reducing the cooling efficiency of the device); (3) the cost is too high and the device loses its value.

[0008] If the material thickness is not adjusted properly, (1) if it is too thick, the transmission band will shift to the right and the average transmittance will decrease, thus reducing the overall transmittance; (2) if it is too thin, the transmission band will shift to the left and the average transmittance will decrease, thus reducing the overall transmittance.

[0009] In summary, existing radiative cooling technology has many difficulties in optimizing optical window performance, adapting to environmental changes, comprehensive energy utilization, and meeting diverse application needs. Summary of the invention

[0010] In view of the shortcomings of the prior art, the present invention designs an optical window structure for radiative cooling, which can effectively block solar radiation and have high transmittance to radiation in the atmospheric window band, improve the performance stability and energy utilization efficiency of the radiative cooling device, and provide strong support for the promotion of radiative cooling technology in practical applications.

[0011] An optical window structure for radiative cooling:

[0012] The structure of the optical window is that metal layers and dielectric layers are alternately stacked;

[0013] The bottom and top layers are both metal layers, which protect the internal dielectric layer while blocking solar radiation through their own optical properties, ensuring that the radiation cooling material is in a relatively low temperature environment;

[0014] The dielectric layer works together with the metal layer to allow the heat radiated by the radiation cooling material to be dissipated into space through the structure in the atmospheric window band, thereby achieving a cooling effect.

[0015] Furthermore, the metal layer is made of Ge, which uses its high blocking rate for solar radiation to reduce the entry of external radiation.

[0016] Furthermore, the material of the dielectric layer is BaF 2 , utilizing its transmittance to the atmospheric window and combining it with Ge to make the optical window structure have high transmittance in the range of 8 to 13 μm.

[0017] Furthermore, the spectral transmittance of the optical window structure is obtained by simulation using a finite difference time domain method.

[0018] Furthermore, the metal layer and the dielectric layer have 11 layers in total, and the thickness of each layer is different;

[0019] The first layer is Ge, 240nm thick; the second layer is BaF 2 , thickness 410nm;

[0020] The third layer is Ge, 530nm thick; the fourth layer is BaF 2 , thick 130nm;

[0021] The fifth layer is Ge, 190nm thick; the sixth layer is BaF 2 , thickness 1160nm;

[0022] The 7th layer is Ge, 160nm thick; the 8th layer is BaF 2 , thickness 1020nm;

[0023] The 9th layer is Ge, 610nm thick; the 10th layer is BaF 2 , thickness 450nm;

[0024] The 11th layer is Ge, with a thickness of 270nm.

[0025] A method for preparing an optical window structure for radiative cooling:

[0026] The preparation method is a magnetron sputtering method;

[0027] First, the chamber of the magnetron sputtering device was evacuated to a vacuum state, and Ge and BaF were installed on the sputtering cathode. 2 Target material;

[0028] Then, argon gas was injected into the chamber as the sputtering gas, and appropriate sputtering power and sputtering time were set. Ge and BaF were alternately deposited on the substrate by deposition method. 2 The material forms an optical window structure in which the metal layers and the dielectric layers are alternately stacked.

[0029] 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.

[0030] 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.

[0031] Beneficial effects of the present invention:

[0032] The optical window structure designed in the patent of this invention has excellent transmittance performance for atmospheric window band (8-13μm) radiation, which broadens the band range of 1μm compared with the existing technology, and the average transmittance exceeds 90% (such as Figure 2 As shown); the radiation cooling material can efficiently dissipate heat to the outside through the window in the form of thermal radiation, thereby improving the radiation cooling efficiency; at the same time, when the solar radiation is strong during the day, it can effectively prevent the refrigeration device from absorbing too much solar heat, resulting in a decrease in cooling effect or even failure.

[0033] The present invention selects Ge and BaF 2 Two materials, and through a specific 11-layer alternating stacking structure (such as Figure 1 As shown in the figure, precise control of radiation in different bands is achieved. At the same time, the high blocking rate of Ge to sunlight band radiation is utilized, and Ge / BaF 2 The high transmittance of the combined structure to atmospheric window band radiation enables high transmittance in the atmospheric window band and low transmittance in unnecessary bands (solar radiation band, etc.), thereby improving the overall performance of the radiation cooling device.

[0034] The present invention fully considers the influence of different angles between outward radiation and the window on the average transmittance (such as Figure 3 As shown). Both transverse magnetic waves (TM) and transverse electric waves (TE) have a high transmittance (higher than 60%) in the range of 0° to 60°, and the average transmittance of electromagnetic waves in the range of 0° to 70° is still higher than 60%; that is, the optical window structure of the present invention can maintain good performance under different angles of radiation incidence, ensuring the stability and reliability of the radiation cooling device in practical applications, and is not significantly affected by changes in radiation angles. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the optical window structure for radiative cooling, where 1 is a metal layer and 2 is a dielectric layer;

[0036] Figure 2 It is a schematic diagram of the transmittance of the window structure in the 0.3-15μm band;

[0037] Figure 3 Schematic diagram of the transmittance of the window structure under transverse magnetic wave and transverse electric wave conditions. DETAILED DESCRIPTION

[0038] 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.

[0039] 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.

[0040] Combination Figures 1 to 3 The present invention proposes an optical window structure for radiative cooling, which regulates the transmission of thermal radiation during the radiative cooling process and improves the performance of the entire radiative cooling device by optimizing the transmission path of thermal radiation.

[0041] 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.

[0042] The structure of the optical window is that metal layers 1 and dielectric layers 2 are alternately stacked;

[0043] The bottom and top layers are both metal layers 1, which protect the internal dielectric layer 2 and block solar radiation through their own optical properties, ensuring that the internal materials are in a relatively low temperature environment;

[0044] The dielectric layer 2 works together with the metal layer 1 to allow the heat radiated by the internal material to be dissipated into space through the structure in the atmospheric window band, thereby achieving a cooling effect.

[0045] The material of the metal layer 1 is Ge. For unnecessary radiation such as solar radiation band, Ge uses its high blocking rate for solar radiation band to prevent these radiations from entering the refrigeration device, avoiding additional heat input, thereby maintaining a low temperature environment inside the refrigeration device.

[0046] The material of the dielectric layer 2 is BaF 2 , utilizing its transmittance to the atmospheric window and combining it with Ge to make the optical window structure have high transmittance in the range of 8 to 13 μm.

[0047] The spectral transmittance of the optical window structure is obtained by simulation using a finite difference time domain method, so as to have high transmittance in the atmospheric window band, that is, 8 to 13 μm.

[0048] The metal layer 1 and the dielectric layer 2 have a total of 11 layers, and the thickness of each layer is different;

[0049] The first layer is Ge, 240nm thick; the second layer is BaF 2 , thickness 410nm;

[0050] The third layer is Ge, 530nm thick; the fourth layer is BaF 2 , thick 130nm;

[0051] The fifth layer is Ge, 190nm thick; the sixth layer is BaF 2 , thickness 1160nm;

[0052] The 7th layer is Ge, 160nm thick; the 8th layer is BaF 2 , thickness 1020nm;

[0053] The 9th layer is Ge, 610nm thick; the 10th layer is BaF 2 , thickness 450nm;

[0054] The 11th layer is Ge, with a thickness of 270nm.

[0055] A method for preparing an optical window structure for radiative cooling:

[0056] The preparation method is a magnetron sputtering method;

[0057] First, the chamber of the magnetron sputtering device was evacuated to a vacuum state, and Ge and BaF were installed on the sputtering cathode. 2 Target material;

[0058] Then, argon gas was injected into the chamber as the sputtering gas, and appropriate sputtering power and sputtering time were set. Ge and BaF were alternately deposited on the substrate by deposition method. 2 The material forms an optical window structure in which the metal layers and the dielectric layers are alternately stacked.

[0059] like Figure 3 , the blue vertical line is the atmospheric window band, i.e. the required band; the red line is the transmittance of the window structure in the corresponding band. For the required band, the average transmittance of the window structure exceeds 90%; for the unnecessary band, the blocking rate of the window structure also reaches a good data, proving that the present invention greatly improves the working efficiency of the radiation cooling material.

[0060] The structure of the present invention also fully considers the change of average transmittance caused by the difference of outward radiation and window angle during the design process, so that the data is more sufficient and referenceable. Figure 3 TM and TE are two forms of electromagnetic waves: the former is transverse magnetic wave and the latter is transverse electric wave. Drawing the graphs separately can more intuitively show that both transverse magnetic wave and transverse electric wave have high transmittance (higher than 60%) at 0°~60°, and the average transmittance of electromagnetic waves at 0°~70° is still higher than 60%.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] The optical window structure for radiative cooling proposed in the present invention is introduced in detail above, and the principle and implementation mode 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 mode and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. An optical window structure for radiative cooling, characterized in that: The optical window has a structure in which metal layers (1) and dielectric layers (2) are alternately stacked; The bottom layer and the top layer are both metal layers (1), which protect the internal dielectric layer (2) and block solar radiation through their own optical properties, thereby ensuring that the radiation cooling material is in a relatively low temperature environment; The dielectric layer (2) works together with the metal layer (1) to allow the heat radiated by the radiation cooling material to be dissipated into space through the structure in the atmospheric window band, thereby achieving a cooling effect.

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

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

4. The optical window structure according to claim 3, characterized in that: The spectral transmittance of the optical window structure is obtained by simulation using the finite difference time domain method.

5. The optical window structure according to claim 4, characterized in that: The metal layer (1) and the dielectric layer (2) have 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, with a thickness of 270nm.

6. A method for preparing an optical window structure for radiative cooling according to any one of claims 1 to 5, characterized in that: The preparation method is a magnetron sputtering method; First, the chamber of the magnetron sputtering device is evacuated to a vacuum state, and Ge and BaF2 targets are installed on the sputtering cathode; Then, argon gas is flushed into the chamber as a sputtering gas, and appropriate sputtering power and sputtering time are set. Ge and BaF2 materials are alternately deposited on the substrate by a deposition method to form an optical window structure in which the metal layer (1) and the dielectric layer (2) are alternately stacked.

7. 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 6 when executing the computer program.

8. A computer-readable storage medium for storing computer instructions, wherein the computer instructions implement the steps of the method of claim 6 when executed by a processor.

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