KR20220082357A - Radiative cooling device based on hole pattern layer - Google Patents

Abstract

The present invention relates to a radiation cooling device using a hole pattern layer, and specifically, a dielectric material having a high extinction coefficient in an atmospheric window (AW) section is deposited on the hole pattern layer to form the atmosphere. It relates to a technology for implementing high infrared absorption and emissivity in the atmospheric window (AW) section, and according to an embodiment of the present invention, the radiation cooling element has a plurality of pores, and the plurality of pores ), the diameter of the plurality of holes and the period of the hole pattern layer formed based on a volume fraction of a dielectric material and air Including, but based on the hole pattern layer absorbs and emits infrared rays in a wavelength range corresponding to an atmospheric window (AW), the thickness of the hole pattern layer (thickness), the diameter (diameter) and the Absorption and emissivity associated with the infrared light may be controlled based on at least one of a period.

Description

Radiation cooling element based on hole pattern layer

The present invention relates to a radiation cooling device using a hole pattern layer, and specifically, a dielectric material having a high extinction coefficient in an atmospheric window (AW) section is deposited on the hole pattern layer to form the atmosphere. It is a technology that realizes high infrared absorption and emissivity in the atmospheric window (AW) section.

A passive radiative cooling device can be passively cooled by reflecting a wavelength (0.3-2.5 μm) corresponding to sunlight during the day and radiating radiant heat (8-13 μm) energy that can escape out of space.

On the other hand, passive radiative heating elements absorb the wavelength (0.3-2.5㎛) corresponding to sunlight during the day and do not absorb radiant heat (8-13㎛) energy that can escape out of space. can be

The efficiency of the passive cooling device can be confirmed by measuring the optical properties of the device itself.

For heat dissipation, it must be able to radiate heat into space as it has a high absorption or emissivity in the long-wavelength infrared region.

According to the Planck distribution, when the temperature is 300K, it has a condition for maximally dissipating heat in the wavelength range of 6-20 μm. In the case of the Earth, the sky window region of the atmosphere is about 8-13 μm, so in order to maximize the heat dissipation capability of the passive cooling element, the absorption or emissivity in the 8-13 μm region should be the maximum.

Infrared radiation in the window wavelength range of the atmosphere plays a key role in achieving radiative cooling by substantial heat release. If the wavelength range reflects 100% of the incident sunlight (emitted from the sun) and radiates 100% of long-wavelength infrared rays in the 8㎛-13㎛ region, which is the window section of the atmosphere, 300K At an ambient temperature of 158W/m2, cooling performance ^of 158W/m2 can be realized without energy consumption.

If 95% of sunlight is reflected and 90% or more of mid-infrared radiation in the 8㎛-13㎛ area is radiated to the outside, the cooling performance ^of 100W/m2 is achieved during the day (ie, there is light absorption by the sun) when the ambient temperature is 300K. And at night when there is no light absorption by the sun, a cooling performance of 120W/m ² can be realized.

In order to be used as a passive radiation cooling material, it has to have high transmittance or high reflectance to light in the UV-vis-NIR wavelength range of incident sunlight, so it must not absorb incident sunlight, and the window section of the atmosphere is 8 to 13 μm. It should have high absorption (emissivity) for long-wavelength infrared rays, and in addition to it, it should have high durability (stability, corrosion resistance) in outdoor conditions, and the materials used should be inexpensive and abundant, and cheap and easy to use. The process should be capable of forming over a large area.

In the case of a polymer material, it generally has a high absorption (emissivity) for long-wavelength infrared rays, but due to the characteristics of the material, it is easily deteriorated by ultraviolet rays and moisture, etc.

In addition, the thick polymer material is a broadband emitter with high emissivity for all infrared wavelength bands, so its radiative cooling performance is lower than that of a selective emitter with high emissivity in the sky window. falls

In the case of using a multi-layer thin film made of an inorganic material or a ceramic material, the number of layers must be large in order to increase the emissivity in the entire window in the atmosphere, which increases the absorption of sunlight, making it difficult to achieve high-efficiency radiative cooling performance.

In addition, it is difficult to apply radiative cooling to real life due to the long-term stability problem (oxidation problem) and cost problem of silver and aluminum in a radiation cooling device including a lower metal reflective layer such as silver or aluminum, and these metal materials mainly use specular reflection This can cause eye strain and light bleed.

Currently, various radiation cooling materials have been developed, but studies on radiation cooling materials using an anodic aluminum oxide membrane (AAO) film have hardly been conducted.

Al ₂ O ₃ constituting the anodic aluminum oxide membrane (AAO) membrane is formed together with the porous membrane, and is known to have high absorption/emissivity in some regions of the window section of the atmosphere.

Although it is used in various fields because it can be easily manufactured in a large area using the bottom-up process, which is a chemical process, there is a problem that it does not have high absorption/emissivity in the entire spectrum of the window section of the atmosphere to be used in a radiation cooling device.

Korean Patent No. 10-1537901, "High heat dissipation transparent sheet and manufacturing method thereof" Korean Patent Registration No. 10-1961585, "Plate glass with heat-radiation-reflecting coating and fastening or sealing element attached thereto" US Patent No. 9927188, "METAMATERIALS-ENHANCED PASSIVE RADIATIVE COOLING PANEL" Korean Patent Application Laid-Open No. 10-2013-0086452, "Anti-reflection optical body provided with porous anodized aluminum oxide film and manufacturing method thereof"

The present invention is to increase the infrared emissivity and absorption rate in the window of the atmosphere based on the hole pattern layer by controlling at least one of the period, diameter and thickness of the hole pattern layer to have high emissivity in the wavelength range corresponding to the window of the atmosphere The purpose.

The present invention uses an effective medium theory (EMT) to provide a hole pattern layer-based radiation cooling with an optimized optical property (permittivity) that can exhibit high absorption and emissivity for infrared rays in the AW section It aims to provide a device.

An object of the present invention is to optimize parameters of period, diameter and thickness related to structural parameters of a hole pattern layer to have high emissivity in a wavelength range corresponding to the window of the atmosphere.

An object of the present invention is to provide a radiation cooling device that cools the ambient temperature without energy consumption even during day time when sunlight is shining or night time when sunlight is not shining.

An object of the present invention is to provide a cooling function without energy consumption by being applied to the outer surface of a material requiring cooling, such as building materials, glass, automobile materials, aviation equipment, energy-saving data centers and electronic devices, and solar cells.

Radiation cooling element according to an embodiment of the present invention has a plurality of pores (pore), a period exists between the plurality of pores (pore), the diameter (diameter) of the plurality of holes (diameter) and the period ( period) includes a hole pattern layer formed based on a volume fraction of a dielectric material and air, and a wavelength corresponding to an atmospheric window (AW) based on the hole pattern layer Absorbing and emitting infrared rays in a range, but based on at least one of the thickness (thickness), the diameter (diameter) and the period (period) of the hole pattern layer, the absorption and emissivity related to the infrared rays may be controlled.

Radiation cooling device according to an embodiment of the present invention on the hole pattern layer SiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , c-BN, ZrO ₂ , MgHPO ₄ , Ta ₂ O ₅ , AlN, LiF , MgF ₂ , HfO ₂ And at least one of BaSO ₄ It may further include a coating layer is coated.

The coating layer may increase the absorptivity and emissivity associated with the controlled infrared.

The thickness of the coating layer may be proportional to the increased absorption and emissivity.

The radiation cooling device may have an infrared emissivity and absorption coefficient of 0.6 or more when the infrared rays are incident at an incident angle of 0 to 50 degrees with respect to a reference line perpendicular to the infrared rays.

The hole pattern layer may have a free-standing porous thin film structure.

The volume fraction of the dielectric material and air may be determined based on a calculated value according to an effective medium theory (EMT).

The dielectric material is selected from among SiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , c-BN, ZrO ₂ , MgHPO ₄ , Ta ₂ O ₅ , AlN, LiF, MgF ₂ , HfO ₂ and BaSO ₄ . It may include at least one.

As the ratio of the dielectric material to the volume fraction increases, the infrared-related absorption and emissivity may increase.

The volume of the air may be proportional to the diameter (diameter).

The calculated value according to the effective medium theory (EMT) may be proportional to the controlled absorption and emissivity.

The radiation cooling device according to an embodiment of the present invention may further include a reflective layer formed of a metal material under the hole pattern layer and reflecting sunlight.

The reflective layer is silver (Ag), aluminum (Al), gold (Au), copper (cu), titanium (Ti), chromium (Cr), manganese (Mn), nickel (Ni), iron (Fe) and platinum ( It may be formed of at least one metal material selected from Pt) or any one of an alloy material in which at least two are combined.

The present invention can increase the infrared emissivity and absorption rate in the window of the atmosphere based on the hole pattern layer by controlling at least one of the period, diameter and thickness of the hole pattern layer to have high emissivity in the wavelength range corresponding to the window of the atmosphere. have.

The present invention uses an effective medium theory (EMT) to provide a hole pattern layer-based radiation cooling device having a coating layer deposited with optimized optical properties (permittivity) that can exhibit high absorption and emissivity for infrared in the AW section can provide

The present invention can optimize the parameters of the period, diameter and thickness related to the structural parameters of the hole pattern layer to have high emissivity in the wavelength range corresponding to the window of the atmosphere.

The present invention can provide a radiation cooling device that cools the ambient temperature without energy consumption even during day time when sunlight is shining or night time when sunlight is not shining.

The present invention can provide a cooling function without energy consumption by being applied to the outer surface of materials that require cooling, such as building materials, glass, automobile materials, aviation equipment, energy-saving data centers and electronic devices, and solar cells.

1 and 2 are views illustrating a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.
3 and 4 are views illustrating a method of manufacturing a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.
5A to 5D are views for explaining various images of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.
6A to 6F are views illustrating optical characteristics of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.
7A to 7C are diagrams for comparing the dielectric constant of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.
8A to 8C are views for comparing absorption and emissivity of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.
9A and 9B are views for explaining the cooling flux of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.
10A to 10D are diagrams for explaining a radiation cooling experiment using a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.
11 is a view for explaining the results of a radiation cooling experiment using a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

Hereinafter, various embodiments of the present document will be described with reference to the accompanying drawings.

Examples and terms used therein are not intended to limit the technology described in this document to a specific embodiment, but it should be understood to include various modifications, equivalents, and/or substitutions of the embodiments.

In the following, when it is determined that a detailed description of a known function or configuration related to various embodiments may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted.

In addition, the terms to be described later are terms defined in consideration of functions in various embodiments, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

In connection with the description of the drawings, like reference numerals may be used for like components.

The singular expression may include the plural expression unless the context clearly dictates otherwise.

In this document, expressions such as “A or B” or “at least one of A and/or B” may include all possible combinations of items listed together.

Expressions such as "first," "second," "first," or "second," can modify the corresponding elements regardless of order or importance, and to distinguish one element from another element. It is used only and does not limit the corresponding components.

When an (eg, first) component is referred to as being “connected (functionally or communicatively)” or “connected” to another (eg, second) component, that component is It may be directly connected to the component or may be connected through another component (eg, a third component).

As used herein, "configured to (or configured to)" according to the context, for example, hardware or software "suitable for," "having the ability to," "modified to ," "made to," "capable of," or "designed to" may be used interchangeably.

In some circumstances, the expression “a device configured to” may mean that the device is “capable of” with other devices or parts.

For example, the phrase "a processor configured (or configured to perform) A, B, and C" refers to a dedicated processor (eg, an embedded processor) for performing the corresponding operations, or by executing one or more software programs stored in a memory device. , may refer to a general-purpose processor (eg, a CPU or an application processor) capable of performing corresponding operations.

Also, the term 'or' means 'inclusive or' rather than 'exclusive or'.

That is, unless stated otherwise or clear from context, the expression 'x employs a or b' means any one of natural inclusive permutations.

Terms such as '.. unit' and '.. group' used below mean a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software.

1 and 2 are views illustrating a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

1 illustrates a cross-sectional view of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

Referring to FIG. 1 , the radiation cooling device 100 according to an embodiment of the present invention includes a reflective layer 110 , a hole pattern layer 120 , and a coating layer 130 .

For example, the reflective layer 110 is formed of a metal material under the hole pattern layer 120 to reflect sunlight.

For example, the reflective layer 110 may include silver (Ag), aluminum (Al), gold (Au), copper (cu), titanium (Ti), chromium (Cr), manganese (Mn), nickel (Ni), and iron. It may be formed of at least one metal material selected from (Fe) and platinum (Pt), or an alloy material in which at least two are combined.

According to an embodiment of the present invention, the hole pattern layer 120 has a plurality of pores, a period exists between the plurality of pores, and the diameter and period of the plurality of holes. ) can be determined based on the volume fraction of the dielectric material and air.

Here, the period 102 and the diameter 103 may be determined according to the thickness of the coating layer 130 .

For example, the radiation cooling element 100 absorbs and radiates infrared rays in a wavelength range corresponding to an atmospheric window (AW) based on the hole pattern layer 110, but the thickness of the hole pattern layer (thickness) Absorption and emissivity associated with infrared light may be controlled based on at least one of , a diameter and a period.

Here, the thickness 101 may be determined according to the formation thickness of the coating layer 130 .

On the other hand, thickness 101, period 102 and diameter 103 are related to the volume fraction of the dielectric material and air.

For example, the volume fraction of the dielectric material and air may be determined based on effective medium theory (EMT).

For example, the diameter 103 may be proportional to the volume of air. That is, when the diameter 103 is increased, the volume of air in the volume ratio of the dielectric material and air is increased.

According to an embodiment of the present invention, the hole pattern layer 120 is formed using a dielectric material, and the dielectric material is SiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , c-BN, ZrO ₂ , MgHPO ₄ , It may include at least one of Ta ₂ O ₅ , AlN, LiF, MgF ₂ , HfO ₂ , and BaSO ₄ .

According to an embodiment of the present invention, the hole pattern layer 110 may have a free-standing porous thin film structure.

According to an embodiment of the present invention, the coating layer 130 is formed on the hole pattern layer 120 on the SiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , c-BN, ZrO ₂ , MgHPO ₄ , Ta ₂ O ₅ , At least one of AlN, LiF, MgF ₂ , HfO ₂ and BaSO ₄ may be coated and formed.

For example, the coating layer 130 may increase the absorption and emissivity related to the controlled infrared light based on the hole pattern layer 120 .

For example, the thickness of the coating layer 130 may be proportional to the increase rate of the absorption rate and the emissivity.

That is, as the thickness of the coating layer 130 increases, the absorption and emissivity of infrared rays may also increase.

According to an embodiment of the present invention, the thickness 101 may be 50 μm, the period 102 may be 500 nm, and the diameter 103 may be 400 nm.

For example, the thickness 101 , the period 102 , and the diameter 103 are SiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , c-BN, ZrO ₂ on the hole pattern layer 120 having the same volume ratio. , MgHPO ₄ , Ta ₂ O ₅ , AlN, LiF, MgF ₂ , HfO ₂ , and BaSO ₄ At least one of the coated structures may be changed.

Therefore, the present invention increases the infrared emissivity and absorption rate in the window of the atmosphere based on the hole pattern layer by controlling at least one of the period, diameter, and thickness of the hole pattern layer to have high emissivity in the wavelength range corresponding to the window of the atmosphere can do it

In addition, the present invention can provide a cooling function without energy consumption by being applied to the outer surface of materials requiring cooling, such as building materials, glass, automobile materials, aviation equipment, energy-saving data centers and electronic devices, and solar cells.

2 illustrates a three-dimensional view of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

Referring to FIG. 2 , the radiation cooling device 200 based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention has a structure in which an infrared radiation layer 220 is formed on a reflective layer 210 .

As an example, the infrared emission layer 220 is a hole pattern layer and SiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , c-BN, ZrO ₂ , MgHPO ₄ , Ta ₂ O ₅ , AlN, LiF, MgF ₂ , At least one of HfO ₂ and BaSO ₄ includes a deposited coating layer.

According to an embodiment of the present invention, the infrared radiation layer 220 may have a free-standing porous thin film structure.

As an example, the infrared radiation layer 220 may have the emissivity and absorption rate for infrared light controlled according to the diameter, period, and thickness of the porous thin film structure.

According to an embodiment of the present invention, the radiation cooling device 200 may perform radiative cooling by absorbing and emitting infrared rays of the incident sunlight when the sun is positioned on the upper surface and incident sunlight.

3 and 4 are views illustrating a method of manufacturing a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

3 is SiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , c-BN, ZrO ₂ , MgHPO ₄ , Ta ₂ O ₅ , AlN, LiF, MgF ₂ , HfO ₂ and A method of manufacturing a hole pattern layer in a radiation cooling device based on a hole pattern layer on which at least one of BaSO ₄ is deposited will be described.

Referring to FIG. 3 , in the method of manufacturing the radiation cooling device in step S300 , a porous structural frame formed on an aluminum (Al) plate is prepared.

In the manufacturing method of the radiation cooling device in step S301, polystyrene is inserted into a porous structural frame.

In the method of manufacturing the radiation cooling device in step S302, the aluminum (Al) plate is removed through a wet etching process.

In the method of manufacturing the radiation cooling device in step S303, the upper and lower surfaces of the structural frame are inverted through a back opening process, and the upper surface is opened after inversion.

In the method of manufacturing the radiation cooling device in step S304, a hole pattern layer having a free-standing porous thin film structure is formed by removing polystyrene in the structural frame.

4 is a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention to form a coating layer by depositing a coating layer, and then a structure formed on a metal plate corresponding to a reflective layer is transferred to manufacture a radiation cooling device explain how to do it.

Referring to FIG. 4 , in step S401 , in the method of manufacturing a radiation cooling device according to an embodiment of the present invention, a hole pattern layer formed according to the step of FIG. 3 is prepared.

In step S402, the method of manufacturing a radiation cooling device according to an embodiment of the present invention forms a coating layer by coating silicon dioxide on the hole pattern layer using an atomic layer deposition (ALD) method.

In step (S403), the method of manufacturing a radiation cooling device according to an embodiment of the present invention is SiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , c-BN, ZrO ₂ , MgHPO ₄ , Ta ₂ O ₅ , AlN , LiF, MgF ₂ , HfO ₂ and BaSO ₄ The hole pattern layer coated with at least one is transferred onto the reflective layer to manufacture a radiation cooling device.

5A to 5D are views for explaining various images of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

5A illustrates a photo image of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention, and FIGS. 5B to 5D are hole patterns on which a coating layer is deposited according to an embodiment of the present invention. An electron microscope image of a layer-based radiative cooling element is illustrated.

Referring to the image 500 of FIG. 5A , the radiation cooling element based on the hole pattern layer on which the coating layer is deposited is shown in white color.

Referring to the image 510 of FIG. 5B , a top view of the radiation cooling device based on the hole pattern layer on which the coating layer is deposited has a porous structure and has a constant diameter and period.

Image 510 shows that the hole diameter of the hole pattern layer decreases from 400 nm to 370 nm after deposition of the coating layer, which may indicate that the thickness of the coating layer is about 30 nm.

Referring to the image 520 of FIG. 5C and the image 530 of FIG. 5D , it can be seen that the hole pattern layer is formed at a constant cycle.

6A to 6F are views illustrating optical characteristics of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

6A and 6B illustrate a change in emissivity according to hole diameter in a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

The graph 600 of FIG. 6A shows the change of hole diameter on the horizontal axis, the change of the emissivity on the vertical axis, and the graph 610 of FIG. 6B shows the change of the wavelength on the horizontal axis and the change of the emissivity on the vertical axis.

That is, the graph 600 and the graph 610 illustrate the relationship between the diameter of the hole and the emissivity.

Referring to the graph 600 and the graph 610, as the diameter of the hole increases, the emissivity increases in the wavelength range of 8 μm to 13 μm.

That is, in the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention, as the diameter of the formed hole increases, the emissivity can be increased in the 8㎛ to 13㎛ corresponding to the wavelength range of the atmospheric window. .

For example, the diameter of the hole may range from 100 nm to 400 nm.

6c and 6d illustrate a change in emissivity according to a coating thickness of a coating layer in a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

The graph 620 of FIG. 6c shows the change in the coating thickness on the abscissa axis, the change in the emissivity on the ordinate axis, and the graph 630 of FIG. 6d shows the change in the wavelength on the abscissa axis and the change of the emissivity on the ordinate axis.

That is, the graph 620 and the graph 630 illustrate the relationship between the coating thickness and the emissivity according to the deposition of the coating layer.

Referring to the graphs 620 and 630 , as the coating thickness increases according to the deposition of the coating layer, the emissivity increases in the wavelength range of 8 μm to 13 μm.

That is, in the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention, as the coating thickness increases according to the deposition of the coating layer, the emissivity increases from 8 μm to 13 μm, which corresponds to the wavelength range of the atmospheric window. can be

For example, the coating thickness according to the deposition of the coating layer may have a range of 0 to 20 nm. Here, the material forming the coating layer is silicon dioxide (SiO ₂ ), but in one embodiment, silicon dioxide may be replaced with any one of the above-described coating materials.

6e and 6f illustrate changes in emissivity according to the thickness of the hole pattern layer on which the coating layer is deposited in the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention.

The graph 640 of FIG. 6E shows the change in the thickness of the hole pattern layer on which the coating layer is deposited on the abscissa axis, and the change in the emissivity on the ordinate axis, and the graph 650 of FIG. 6f shows the change of wavelength on the abscissa axis and the emissivity on the ordinate axis represents a change in

That is, the graph 640 and the graph 650 illustrate the relationship between the thickness of the hole pattern layer on which the coating layer is deposited and the emissivity.

Referring to graphs 640 and 650 , as the thickness of the hole pattern layer on which the coating layer is deposited increases, the emissivity increases in a wavelength range of 8 μm to 13 μm.

That is, in the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention, as the thickness of the hole pattern layer on which the coating layer is deposited increases, the emissivity at 8 μm to 13 μm corresponding to the wavelength range of the atmospheric window can be increased.

For example, the thickness of the hole pattern layer on which the coating layer is deposited may have a range of 1 μm to 50 μm.

According to the graph 640 and the graph 650, although the content of aluminum oxide (Al ₂ O ₃ ) is increased, it can be confirmed that the highest emissivity is exhibited when the thickness is 50 μm. Here, the material for forming the hole pattern layer is described using aluminum oxide, but it may be substituted with another material for forming the hole pattern layer described above.

7A to 7C are diagrams for comparing the dielectric constant of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

7A illustrates the dielectric constant of aluminum oxide according to the prior art, FIG. 7B illustrates the dielectric constant of an anodized aluminum oxide film according to the prior art, and FIG. 7C is a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention. Illustrating the dielectric constant of the radiative cooling element of

Referring to the graph 700 of FIG. 7A , a change in permittivity according to a change in wavelength is divided into a real number 701 and an imaginary number 702 , and the horizontal axis indicates the permittivity.

In addition, referring to the graph 710 of FIG. 7B , the change in the permittivity according to the change of the wavelength is divided into a real number 711 and an imaginary number 712 , and the horizontal axis indicates the permittivity.

Similarly, referring to the graph 720 of FIG. 7C , the change in the permittivity according to the change of wavelength is divided into a real number 721 and an imaginary number 722 , and the horizontal axis indicates the permittivity.

Referring to Fig. 7a, the exposed Al ₂ O ₃ layer shows that the real number 701 is lower than the imaginary number 702 in the wavelength range of 10 μm or less, indicating that it is insufficient to be used alone as a material of a radiation cooler.

Referring to FIG. 7B , the anodized aluminum oxide film according to the prior art having a porous arrangement pattern has an imaginary number 712 having an effective permittivity relatively high compared to a real number 711 in the window section of the atmosphere.

However, it can be seen that the strong peak of the imaginary number 712 in the vicinity of 11 μm in the wavelength range is much preferable in the radiation cooler, but the imaginary number 712 lower than the low real number 711 in the wavelength range of 8 to 10 μm is inappropriate.

Referring to Figure 7c, the disadvantage of the anodized aluminum film according to the prior art is compensated by the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention, so that the imaginary number 722 is a real number in the range of 8 to 10 μm. It has an imaginary number (722) that is about 0.5 higher than (721).

The above-described imaginary numbers 702 , 712 , and 722 are related to Effective medium theory (EMT), when the imaginary numbers 702, 712 and 722 are greater than zero. The medium absorbs light because the electrical field is lowered.

Accordingly, the volume fraction of the dielectric material and air may be determined based on a calculated value according to an effective medium theory (EMT).

In addition, an imaginary number among the calculated values according to the effective medium theory (EMT) may be proportional to the absorption rate and the emissivity.

The relationship between the permittivity and the imaginary number of absorption can be expressed by the following [Equation 1] for the electric field of light propagating in the medium along the z-axis.

[Equation 1]

In [Equation 1], E ₀ may represent the electric field amplitude, ω may represent the angular frequency, k = nk ₀ may represent the wave vector of the medium, where n may represent the refractive index of the medium, k ₀ may represent a wave vector in free space.

On the other hand, when k is substituted in [Equation 1] for the above-described k, it may be as in [Equation 2].

[Equation 2]

는 증폭 부분을 나타낼 수 있고,

는 위상 부분을 나타낼 수 있다. 증폭 부분은 허수부(e'')가 0 이상일 경우에만 상수이고, 나머지는 감쇠 기능이 존재한다. 따라서, 유전율의 허수는 0 이하에서 빛을 흡수한다.In [Equation 2]

may represent an amplification moiety,

may represent a phase part. The amplification part is constant only when the imaginary part e'' is equal to or greater than 0, and the rest has an attenuation function. Therefore, the imaginary number of permittivity absorbs light below zero.

In other words, parameters such as thickness, diameter, coating thickness, and period on the radiation cooling element based on the hole pattern layer on which the coating layer is deposited according to the effective medium theory (EMT) can be optimized for optimal emissivity. have.

Accordingly, the present invention can optimize the parameters of the period, diameter and thickness related to the structural parameters of the hole pattern layer to have high emissivity in the wavelength range corresponding to the window of the atmosphere.

In addition, the present invention uses an effective medium theory (EMT) to show a high absorption rate and emissivity for infrared rays in the AW section, and has an optimized optical property (permittivity) based on a hole pattern layer on which a coating layer is deposited. A cooling element may be provided.

8A to 8C are views for comparing absorption and emissivity of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

Figure 8a illustrates the emissivity simulation result of the anodized aluminum film according to the prior art, Figure 8b is the emissivity simulation result of the radiation cooling element based on the hole pattern layer in which the coating layer is deposited according to an embodiment of the present invention based on the effective dielectric constant 8c compares the prior art with the present invention.

The graph 800 of FIG. 8A , the graph 810 of FIG. 8B , and the graph 820 of FIG. 8C represent changes in wavelength on the horizontal axis and changes in emissivity on the vertical axis.

Referring to the graph 800 of FIG. 8A , the anodized aluminum oxide film according to the prior art generates a spectrum having a high emissivity band in a wavelength range of 10 to 13.5 μm, but low emissivity in the window section of the remaining atmosphere, 8 μm to 10 μm. indicates

Referring to the graph 810 of FIG. 8B , the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention has an average emissivity of 0.7 to 0.89 in the entire window of the atmosphere.

Referring to the graph 820 of FIG. 8C , the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention is compared to the prior art in the entire window (8 μm to 13 μm) in the atmosphere. It can be seen that all of them have high emissivity.

9A and 9B are views for explaining the cooling flux of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

Figure 9a illustrates the theoretical cooling flux of a designed radiation cooler as a function of temperature when hcc = 6 Wm-2K-1, and Figure 9b illustrates the theoretical cooling of the radiation cooler as a function of temperature difference T at Tamb = 303 K to various hcc. Flux is exemplified.

The graph 900 of FIG. 9A shows the change in absolute temperature on the abscissa axis and the cooling flux on the ordinate axis.

The graph 910 of FIG. 9B shows the temperature difference on the horizontal axis and the cooling flux on the vertical axis.

Referring to the graph 900 of FIG. 9A , the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention exhibits a cooling flux of 140 W/m ^-2k or more at 303K.

Referring to the graph 910 of FIG. 9B , the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention has a positive cooling effect as it has 287.5K, which is about 15.5K lower than the ambient temperature. can confirm.

10A to 10D are diagrams for explaining a radiation cooling experiment using a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

10A illustrates a schematic diagram for a surface cooling measurement experiment of a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

Referring to FIG. 10A, in the surface cooling measurement experiment environment 1000, a transparent acrylic 1002 plate is positioned between the wood frames 1001, polystyrene 1003 is positioned on a transparent acrylic 1002 plate, and polystyrene 1003 is on A sample 1004 is positioned on the sample 1004, and a thermometer is positioned on the polystyrene 1003, and a thermometer is additionally positioned to measure the temperature of the atmosphere.

Further, the open upper area of the wood frame 1001 is covered by polyethylene 1006 , and the polyethylene 1006 is positioned between the aluminum foils 1005 .

10B compares the emissivity between a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention and a comparison target in which white paint is applied to a metal plate.

Referring to the graph 1010 of FIG. 10B , the horizontal axis of the graph 1010 indicates a change in wavelength, and the vertical axis indicates a change in emissivity.

Comparing the graph line 1011 corresponding to the radiation cooling element based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention is compared with the graph line 1012 corresponding to the comparison target in which white paint is applied to the metal plate, The emissivity of the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention is relatively excellent in the window section of the atmosphere.

FIG. 10c compares the emissivity with respect to the incident angle of infrared rays between the radiation cooling device based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention and a comparison object in which white paint is applied to a metal plate.

Referring to the graph 1020 of FIG. 10C , in the radiation cooling device according to an embodiment of the present invention, when infrared rays are incident at an incident angle of 0 degrees to 50 degrees with respect to a reference line perpendicular to infrared rays, infrared emissivity and absorption coefficient of 0.6 or more can have

On the other hand, a comparison object coated with white paint on a metal plate has an emissivity of 0.3 to 0.4 under the same conditions.

10D illustrates a photo image 1030 of the surface cooling measurement experimental environment 1000 described in FIG. 10A .

11 is a view for explaining the results of a radiation cooling experiment using a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

11 illustrates a temperature measurement experiment result by a radiation cooling device based on a hole pattern layer on which a coating layer is deposited according to an embodiment of the present invention.

Referring to the graph 1100 of FIG. 11 , the change in temperature according to the change of solar irradiance and time is measured by the radiation cooling element 1101 based on the hole pattern layer on which the coating layer is deposited according to an embodiment of the present invention, the metal ( 1102 ) and indoor 1103 .

The radiation cooling element 1101 has a lower temperature compared to the metal 1102 and the room 1103 .

Therefore, it can be confirmed that the radiation cooling element 1101 efficiently cools the ambient temperature even during the day when the sun is shining.

In addition, the present invention can provide a radiation cooling device that cools the ambient temperature without energy consumption even during day time when sunlight is shining or night time when sunlight is not shining.

In addition, the present invention can be applied to the external surface of materials that require cooling, such as building materials, glass, automobile materials, aviation equipment, energy-saving data centers and electronic devices, and solar cells, to provide a cooling function without energy consumption.

In the above-described specific embodiments, elements included in the invention are expressed in the singular or plural according to the specific embodiments presented.

However, the singular or plural expression is appropriately selected for the situation presented for convenience of description, and the above-described embodiments are not limited to the singular or plural component, and even if the component is expressed in plural, it is composed of a singular or , even a component expressed in a singular may be composed of a plural.

On the other hand, although specific embodiments have been described in the description of the invention, various modifications are possible without departing from the scope of the technical idea contained in the various embodiments.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims described below as well as the claims and equivalents.

100: radiant cooling element 101: thickness
102: cycle 103: diameter
110: reflective layer 120: hole pattern layer
130: coating layer

Claims (13)

having a plurality of pores, wherein a period exists between the plurality of pores, and a diameter of the plurality of pores and the period is determined by a ratio between a dielectric material and air A hole pattern layer formed based on a volume fraction,
Absorbing and emitting infrared rays in a wavelength range corresponding to an atmospheric window (AW) based on the hole pattern layer, the thickness of the hole pattern layer, the diameter, and the period ), characterized in that the absorption and emissivity related to the infrared light are controlled based on at least one of
Radiant cooling element. According to claim 1,
SiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , c-BN, ZrO ₂ , MgHPO ₄ , Ta ₂ O ₅ , AlN, LiF, MgF ₂ , HfO 2 At least one of MgF 2 , HfO ₂ and BaSO ₄ on the hole pattern layer Characterized in that it further comprises a coating layer to be coated
Radiant cooling element. 3. The method of claim 2,
The coating layer is characterized in that it increases the absorptivity and emissivity related to the controlled infrared.
Radiant cooling element. 4. The method of claim 3,
The thickness of the coating layer is characterized in that proportional to the increased absorption and emissivity
Radiant cooling element. 3. The method of claim 2,
The radiation cooling element has an infrared emissivity and absorption coefficient of 0.6 or more when the infrared rays are incident at an incident angle of 0 to 50 degrees with respect to a reference line perpendicular to the infrared rays
Radiant cooling element. According to claim 1,
The hole pattern layer is characterized in that it has a free-standing porous thin film structure.
Radiant cooling element. The method of claim 1,
The dielectric material and the volume fraction of air are determined based on a calculated value according to an effective medium theory (EMT)
Radiant cooling element. 8. The method of claim 7,
The dielectric material is selected from among SiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , c-BN, ZrO ₂ , MgHPO ₄ , Ta ₂ O ₅ , AlN, LiF, MgF ₂ , HfO ₂ and BaSO ₄ . comprising at least one
Radiant cooling element. 9. The method of claim 8,
wherein as the ratio of the dielectric material in the volume fraction increases, the infrared-related absorption and emissivity increase.
Radiant cooling element. 8. The method of claim 7,
The volume of the air is characterized in that proportional to the diameter (diameter)
Radiant cooling element. 8. The method of claim 7,
The calculated value according to the effective medium theory (EMT) is characterized in that it is proportional to the controlled absorption and emissivity
Radiant cooling element. According to claim 1,
A reflective layer formed of a metal material under the hole pattern layer and reflecting sunlight, characterized in that it further comprises
Radiant cooling element. 13. The method of claim 12,
The reflective layer is silver (Ag), aluminum (Al), gold (Au), copper (cu), titanium (Ti), chromium (Cr), manganese (Mn), nickel (Ni), iron (Fe) and platinum ( Pt), characterized in that it is formed of at least any one metal material selected from or an alloy material in which at least two are combined.
Radiant cooling element.

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