KR102479743B1 - Colored radiative cooling device - Google Patents

Abstract

The present application relates to a color type radiation cooling device including a selective heat transmission layer between a wavelength selective transmission layer and a mid-infrared ray emission layer, and a method for cooling an object using the color type radiation cooling device.

Description

Color-type radiant cooling device {COLORED RADIATIVE COOLING DEVICE}

The present application relates to a color type radiation cooling device including a selective heat transmission layer between a wavelength selective transmission layer and a mid-infrared ray emission layer, and a method for cooling an object using the color type radiation cooling device.

A radiant cooling device is a device that automatically cools the ambient temperature even under sunlight without the inflow of external energy. The presence of such helpful radiant cooling devices could have a major impact on the global energy industry.

Until now, only research on improving cooling performance has been active, and conventional radiation cooling devices can only express limited colors such as white paint or mirrors, so it is difficult to apply them to applications where aesthetic factors are important, such as vehicles and houses. Therefore, recently, research is being conducted to develop a color-type radiation cooling device, and a paper [Li, Wei, et al. "Photonic thermal management of colored objects." Nature communications 9.1 (2018): 4240] discloses a color-type radiation cooling device with a multi-layer structure that controls sunlight and mid-infrared rays, but has cooling performance that realizes only a temperature higher than 10 ° C. or higher than the atmosphere. The main reason for this is that the solar energy absorbed for color expression is greater than the radiant heat emission, so it means that it is impossible to simultaneously implement arbitrary color and cooling below the ambient temperature with the conventional color-type radiation cooling device design method. In addition, even if cooling is implemented under a specific color and ambient temperature, the radiation cooling material of the conventional color-type radiation cooling device is exposed to the outside, so the temperature difference between the atmosphere and the radiation cooling device causes energy absorption by conduction and convection in the atmosphere. The better the radiant cooling efficiency, the stronger the heat absorption. At this time, since residual heat absorption by conduction and convection of the atmosphere is proportional to the strength of the wind, unstable cooling performance may be induced depending on the weather.

Accordingly, in the present art, there is a demand for a color-type radiation cooling device capable of stably cooling to a temperature below the ambient temperature and implementing colors.

The present application relates to a color-type radiation cooling device that exhibits excellent radiation cooling performance while realizing color by including a selective heat transmission film between a wavelength selective transmission layer and a mid-infrared emission layer.

However, the problem to be solved by the present application is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

A first aspect of the present invention provides a color type radiation cooling device including a selective heat transmission layer between a wavelength selective transmission layer and a mid-infrared emission layer.

A second aspect of the present disclosure provides a method for cooling an object using the color radiation cooling device according to the first aspect.

In the color-type radiation cooling device according to the embodiments of the present application, a selective heat transmission film is introduced between the mid-infrared ray emission layer, which is a radiation cooling material, and the wavelength selective transmission layer, which is a color implementation material, so that the mid-infrared emission layer and the wavelength selective transmission layer are thermally As a separate design, it is possible to express vivid colors and excellent radiation cooling performance at the same time by independently controlling color implementation and radiation cooling performance. Specifically, it is possible to realize all colors such as R, G, and B through the wavelength selective transmission layer, and at the same time cool 10 ° C to 20 ° C above the ambient temperature through the selective heat transmission layer and the mid-infrared ray emission layer. Theoretically, can provide a color-type radiation cooling device that can be cooled to 50 ° C or higher. Considering that the cooling performance expression temperature of the prior art radiation cooling device that does not implement color is less than 10 ° C. from the ambient temperature, the color type radiation cooling device of the present application is in accordance with the prior art in terms of color implementation and cooling performance. It has superior features.

The color type radiation cooling device according to the embodiments of the present application independently adjusts the mid-infrared ray transmittance of the wavelength selective transmission layer, the mid-infrared ray transmittance of the selective heat transmission film, and the mid-infrared ray absorptivity of the mid-infrared radiation layer, respectively, to improve the overall cooling performance of the device. Since it can be maximized, it is possible to design appropriate color implementation and cooling performance for each application.

In the color-type radiation cooling device according to the embodiments of the present application, since the mid-infrared ray emission layer is blocked from the external atmosphere by the wavelength selective transmission layer and the selective heat transmission membrane, heat conduction by external air and residual heat absorption due to convection can be prevented. there is. In addition, since the temperature of the wavelength selective transmission layer is higher than the atmosphere due to sunlight absorption, the atmosphere rather functions to lower the temperature of the wavelength selective transmission layer, so that the cooling performance of the color type radiation cooling device of the present application can be further improved. Compared to the prior art, the color-type radiant cooling device of <RTI ID=0.0>can implement colors while being able to stably cool to below the ambient temperature regardless of the weather.

Since the color-type radiation cooling device according to the embodiments of the present application can implement semi-permanent cooling performance without using energy, it can supplement and replace all cooling and cooling systems that consume energy to lower the temperature of the refrigerant. It can be applied to small devices such as solar cells and LEDs, as well as commercial buildings, houses, ships, automobiles, roads, etc., and can contribute to aesthetic effects and energy consumption efficiency improvement by imparting cooling performance while realizing colors.

1 is a schematic diagram showing a structure (a) and required performance (b) for each wavelength of a color type radiation cooling device according to an embodiment of the present invention.
2 is a schematic diagram of a structure (a) of a wavelength selective transmission layer according to an embodiment of the present disclosure and a graph showing performance (b) for each wavelength.
3 is a schematic diagram showing a sample (a) and a structure (b) of a wavelength selective transmission layer expressing a red color in one embodiment of the present application.
Figure 4 is a schematic diagram showing a sample (a) of a wavelength selective transmission layer that does not express a vivid color such as RGB and its structure (b) in a comparative example of the present application.
5 is a graph confirming the reflectance of the wavelength selective transmission layer according to Examples and Comparative Examples in wavelengths of visible light and near-infrared light in an embodiment of the present application.
6 is a graph confirming the reflectance and transmittance of the wavelength selective transmission layer according to Examples and Comparative Examples at a wavelength in the mid-infrared region according to an embodiment of the present application.
7 is a graph confirming the cooling expression temperature versus the air temperature during one day of the radiation cooling device according to the Example and the Comparative Example according to an embodiment of the present application.

Throughout this specification, when a part is said to be “connected” to another part, this includes not only the case of being “directly connected” but also the case of being “electrically connected” with another element in between. do.

Throughout the present specification, when a member is said to be located “on” another member, this includes not only a case where a member is in contact with another member, but also a case where another member exists between the two members.

Throughout the present specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated. As used throughout this specification, the terms "about", "substantially", and the like, are used at or approximating that number when manufacturing and material tolerances inherent in the stated meaning are given, and do not convey the understanding of this application. Accurate or absolute figures are used to help prevent exploitation by unscrupulous infringers of the disclosed disclosure.

The term "step of (doing)" or "step of" as used throughout the present specification does not mean "step for".

Throughout this specification, the term “combination(s) of these” included in the expression of the Markush form means a mixture or combination of one or more selected from the group consisting of the components described in the expression of the Markush form, It means including one or more selected from the group consisting of the above components.

Throughout this specification, reference to “A and/or B” means “A or B, or A and B”.

Throughout this specification, “sunlight” means electromagnetic waves that are introduced from the sun and include ultraviolet rays, visible light, and near infrared rays (0.3 μm to 4 μm).

Throughout the present specification, "mid-IR (MIR)" refers to electromagnetic waves with a wavelength of 8 μm to 13 μm that the atmosphere cannot absorb among infrared rays emitted by a black body from an object.

Hereinafter, embodiments and embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the disclosure may not be limited to these embodiments and examples and drawings.

A first aspect of the present application provides a color type radiation cooling device including a selective heat transmission film between a wavelength selective transmission layer and a mid-infrared emission layer.

In one embodiment of the present application, the wavelength selective transmission layer may express color, the mid-infrared ray emission layer implements radiation cooling, and the selective heat transmission membrane may block heat exchange.

In general, radiation cooling devices have to reflect more than 90% of incident sunlight for radiation cooling below atmospheric temperature, so conventional radiation cooling devices have limitations in implementing only limited colors such as white. On the other hand, this application is a color-type radiation cooling device that maximizes both vivid color and cooling performance through thermal separation design and optical composite design.

Specifically, the radiation cooling device is designed to maximize reflection or scattering in order to block sunlight, which is a major heat source. On the other hand, only specific wavelengths within the visible light range (0.4 μm to 0.8 μm) must be reflected in order to implement color. That is, in order to implement a color-type radiation cooling device, only light of a specific wavelength must be reflected to express color, and absorption of light of other wavelengths must be blocked for cooling. However, the conventional radiation cooling device has no choice but to reflect light of a specific wavelength and absorb light of other wavelengths, which is transmitted to an object inside and serves to increase the temperature of the object. When even some of the sunlight is absorbed by an internal object, it is difficult to impart cooling performance in a temperature range lower than the ambient temperature, so conventional color-type radiation cooling devices have limitations in achieving color implementation and cooling performance at the same time.

The color-type radiation cooling device according to the present application is designed to thermally separate the mid-infrared ray emission layer, which is a radiation cooling material, and the wavelength selective transmission layer, which is a color material, and a selective heat transmission film is placed between the two materials to block heat exchange, thereby providing stable color. At the same time as the expression, excellent cooling performance below atmospheric temperature can be realized. The selective heat transmission film blocks heat transfer from the wavelength selective transmission layer, which is a high temperature state, to the mid-infrared ray emission layer, which is a relatively low temperature state, due to some sunlight absorption, thereby enabling simultaneous implementation of color and cooling performance. Therefore, if an object requiring cooling is bonded to the mid-infrared ray emission layer, the object can be cooled to a temperature lower than that of the air without consuming energy. In addition, since the present application is designed to separate the wavelength selective transmission layer and the mid-infrared ray emission layer, the color-type radiation cooling device according to the present application can achieve extreme cooling efficiency and arbitrary colors in that it is possible to optimize design by focusing only on the unique function of each layer. There are advantages to implementing both at the same time.

Referring to FIG. 1, the color type radiation cooling device according to the present invention includes a wavelength selective transmission layer, a selective heat transmission layer, and a mid-infrared ray emission layer in order from top to bottom (FIG. 1 a). Different optical properties are required for each layer (Fig. 1b), and to realize this, each layer must be designed with different materials and structures.

In one embodiment of the present application, the wavelength selective transmission layer is a first type, reflects a first wavelength of a color to be implemented among incident sunlight, absorbs sunlight other than the first wavelength, and emits mid-infrared rays. (hereinafter, referred to as a first type of wavelength selective transmission layer). Specifically, the first type of wavelength-selective transmission layer on top of the color-type radiation cooling device of the present application reflects only the target wavelength of the color to be realized among sunlight while absorbing all other wavelengths of sunlight, and at the same time to realize radiation cooling performance. Wavelengths in the mid-infrared region are transmitted without reflection or absorption so that they are introduced into the selective heat transmission layer and the mid-infrared emission layer.

In one embodiment of the present application, the wavelength selective transmission layer has a second form, reflects or transmits a first wavelength of a color to be implemented among incident sunlight, and absorbs sunlight other than the first wavelength, It may transmit mid-infrared rays (hereinafter referred to as a second type of wavelength selective transmission layer). Specifically, the second type of wavelength selective transmission layer on the top of the color-type radiation cooling device of the present application reflects or transmits only the target wavelength of the color to be implemented among sunlight, while absorbing all other wavelengths of sunlight, and at the same time realizes radiation cooling performance For this purpose, wavelengths in the mid-infrared region are transmitted without reflection or absorption so that they are introduced into the selective heat transmission layer and the mid-infrared radiation layer.

In one embodiment of the present application, the wavelength selective transmission layer may be in the form of a multilayer thin film, a nanopattern, or a polymer layer including dispersed nanoparticles, but is not limited thereto. In the color-type radiation cooling device of the present application, the wavelength selective transmission layer and the mid-infrared ray emission layer are designed separately and can be freely changed in shape to maximize optical properties, so the wavelength selective transmission layer is a multilayer thin film, nanopattern, or dispersed nanoparticles In addition to the form of a polymer layer containing a, wavelength selective transmission layers of other forms may be used without limitation.

In one embodiment of the present application, the wavelength selective transmission layer is zinc sulfide (ZnS), barium fluoride (BaF ₂ ), zinc selenide (ZnSe), calcium fluoride (CaF ₂ ), sodium chloride (NaCl), bromide Potassium (KBr), potassium chloride (KCl), silver chloride (AgCl), silver bromide (AgBr), cesium iodide (CsI), rubidium chloride (RbCl), magnesium fluoride (MgF ₂ ), diamond, thallium bromoiodide (thallium Bromoiodide, TlBrI; KRS-5), titanium oxide (TiO ₂ ), zircon oxide (ZrO ₂ ), zinc oxide (ZnO), silicon oxide (SiO ₂ ) oxides, nitrides such as silicon nitride (Si ₃ N ₄ ), organic/inorganic At least one compound selected from the group consisting of pigments and organic/inorganic dyes may be in a laminated form, but is not limited thereto.

In one embodiment of the present application, the first substrate of the wavelength selective transmission layer of the first type is glass, quartz, polyethylene (PE), polypropylene (PP), polyimide (PI), polystyrene (PS), polyethylene tere It may include one or more compounds selected from the group including phthalate (PET), germanium (Ge), silicon (Si), and gallium arsenide (GaAs), but is not limited thereto. Specifically, the wavelength selective transmission layer of the first type may be in the form of a multilayer thin film, in which case the multilayer thin film is zinc sulfide (ZnS), barium fluoride (BaF ₂ ), zinc selenide (ZnSe), calcium fluoride (CaF ₂ ) ), sodium chloride (NaCl), potassium bromide (KBr), potassium chloride (KCl), silver chloride (AgCl), silver bromide (AgBr), cesium iodide (CsI), rubidium chloride (RbCl), magnesium fluoride (MgF ₂ ) Oxides, such as diamond, thallium bromoiodide (TlBrI; KRS-5), titanium oxide (TiO ₂ ), zircon oxide (ZrO ₂ ), zinc oxide (ZnO), silicon oxide (SiO ₂ ), silicon nitride ( At least one compound selected from the group consisting of nitrides such as Si ₃ N ₄ ), organic-inorganic pigments, and organic-inorganic dyes is glass, quartz, polyethylene (PE), polypropylene (PP), polyimide (PI), and polystyrene (PS). ), polyethylene terephthalate (PET), germanium (Ge), silicon (Si), and gallium arsenide (GaAs). . Also, at this time, the first substrate may absorb sunlight and transmit mid-infrared rays.

In one embodiment of the present application, the second substrate of the wavelength selective transmission layer of the second type is sodium chloride (NaCl), potassium bromide (KBr), potassium chloride (KCl), zinc sulfide (ZnS), silver chloride (AgCl) ), silver bromide (AgBr), cesium iodide (CsI), and at least one compound selected from the group including diamond, but is not limited thereto. Specifically, the wavelength selective transmission layer of the second type may be in the form of a multilayer thin film, in which case the multilayer thin film is zinc sulfide (ZnS), barium fluoride (BaF ₂ ), zinc selenide (ZnSe), calcium fluoride (CaF ₂ ) ), sodium chloride (NaCl), potassium bromide (KBr), potassium chloride (KCl), silver chloride (AgCl), silver fluoride (AgBr), cesium iodide (CsI), rubidium chloride (RbCl), magnesium fluoride (MgF ₂ ) Oxides, such as diamond, thallium bromoiodide (TlBrI; KRS-5), titanium oxide (TiO ₂ ), zircon oxide (ZrO ₂ ), zinc oxide (ZnO), silicon oxide (SiO ₂ ), silicon nitride ( At least one compound selected from the group consisting of nitrides such as Si ₃ N ₄ ), organic-inorganic pigments, and organic-inorganic dyes is sodium chloride (NaCl), potassium bromide (KBr), potassium chloride (KCl), zinc sulfide (ZnS), It may be a multi-layered form on a second substrate including at least one compound selected from the group consisting of silver chloride (AgCl), silver bromide (AgBr), cesium iodide (CsI), and diamond. In this case, the second substrate may transmit sunlight and mid-infrared rays, and the compound(s) stacked on the second substrate may be applied in a solar light region other than the first wavelength of the color to be implemented among the incident sunlight. All of the wavelengths of may be absorbed.

Referring to FIG. 2, a first type of wavelength-selective transmission layer of a multi-layer thin film structure is implemented by using Ge, ZnS, and BaF ₂ that are transparent at wavelengths in the near-infrared to mid-infrared region, and Ge on a Ge substrate that has high solar absorption and is transparent in the mid-infrared range. (Fig. 2a). A thin film containing ZnS or BaF ₂ causes an interference effect of light to reflect only a specific wavelength in sunlight and transmits the remaining sunlight to be absorbed by Ge. It can be confirmed that the wavelength selective transmission layer implements R, G, and B colors, absorbs sunlight other than the reflected wavelength, and transmits mid-infrared rays (FIG. 2B). By controlling the selection of materials constituting the multilayer thin film, the number of thin films, the thickness of the thin film, and/or the periodic pattern, it is possible to select the wavelength of sunlight reflected from the wavelength selective transmission layer, and at the same time, sunlight other than the selected wavelength to Ge. It can be absorbed and allowed to transmit mid-infrared rays so that they can be introduced into the selective heat transmission membrane and the mid-infrared radiation layer. In addition, the Ge can absorb sunlight and simultaneously act as an antireflection layer in the mid-infrared wavelength region so that 80% or more, 90% or more, or 95% or more of mid-infrared rays can be selectively transmitted through the heat-transmitting film without reflection. there is.

In one embodiment of the present application, the selective heat transmission layer may transmit mid-infrared rays and block heat transfer from the wavelength selective transmission layer to the mid-infrared emission layer. Specifically, since all wavelengths of the solar light region are reflected or absorbed in the first type of wavelength selective transmission layer on the upper side, the selective heat transmission film does not need to consider sunlight and is designed to block only heat transfer. That is, the selective heat transmission membrane is designed to block heat exchange between a relatively high-temperature wavelength-selective transmission layer and a relatively low-temperature mid-infrared radiation layer by minimizing thermal conductivity, and at the same time, it is designed to transmit all of the mid-infrared rays without absorbing them. Not only the mid-infrared rays introduced from the upper wavelength selective transmission layer, but also the mid-infrared rays emitted from the lower mid-infrared radiation layer are transmitted. In addition, since the sunlight of the color to be implemented in the second type of wavelength selective transmission layer on the top is reflected or transmitted, and all other sunlight is absorbed, the selective heat transmission film considers solar light control and heat transfer at the same time designed to block That is, the selective heat transmission membrane is designed to block heat exchange between a relatively high-temperature wavelength-selective transmission layer and a relatively low-temperature mid-infrared radiation layer by minimizing thermal conductivity, and transmits both mid-infrared rays and sunlight without absorbing them. It is designed to transmit not only mid-infrared rays and sunlight introduced from the upper wavelength selective transmission layer, but also mid-infrared rays and sunlight emitted from the lower mid-infrared radiation layer.

In one embodiment of the present application, the selective heat permeable membrane may include one or more selected from the group consisting of vacuum, air, polymer membrane, polymer pattern, and polymer pillar, but is not limited thereto. Specifically, the components of the selective heat transmission film are materials that are transparent to mid-infrared rays (including solar light when the second type wavelength selective transmission layer is used) without limitation, but when metal or semiconductor is used, relatively heat conduction Since the degree is high, there is a restriction in that the thickness of the selective heat transmission membrane must be composed of several meters. Therefore, it is preferable to use a material with low thermal conductivity. As an example, the present application designed a selective heat transmission membrane by patterning a high molecular weight polymer having excellent heat blocking effect even with a thin thickness (FIG. 1). The polymer may be one or more selected from the group consisting of poly(dimethylsiloxane) (PDMS), polyethylene (PE), polystyrene (PS), and polypropylene (PP).

In one embodiment of the present application, the polymer pattern may be of a lattice type including a plurality of lattice units having a period, and the lattice width of the lattice unit may be 1/10 or less of the period, but is limited thereto. It doesn't work.

In one embodiment of the present application, the thickness of the selective heat transmission membrane may be 5 cm or less, but is not limited thereto.

Specifically, the space between the patterns of the lattice-type polymer pattern may be filled with vacuum or air, and since the vacuum or air has lower thermal conductivity than the polymer polymer, the area of the polymer pattern relative to the portion in contact with the wavelength selective transmission layer As the effective thermal conductivity is reduced and the area of the vacuum or air is widened, a more effective selective heat transmission membrane can be implemented. However, if the area of vacuum or air is too wide and the area of the polymer pattern is reduced, problems such as mechanical strength and stability may occur, so the lattice width in the lattice unit (w in FIG. 1 a) is the period ( It is preferable to constitute less than 1/10 of p) in FIG. 1 a. In addition, since the lattice-like polymer pattern has a lattice-like shape, convection can be prevented when air is present therein, so cooling performance can be maximized. In addition, when there is air inside, heat transfer due to convection of air can be additionally prevented by disposing a polymer film at a specific height of the polymer pattern.

In one embodiment of the present application, the selective heat permeable membrane may include air and a polymer pattern, and an area ratio between the air and the polymer pattern and a thickness of the selective heat permeable membrane may be determined according to an allowable surface power density. . Specifically, the area ratio of vacuum or air to the polymer (lattice width in the lattice unit) and the thickness of the selective heat permeable membrane may be determined according to the required cooling performance, that is, the allowable surface power density. More specifically, the allowable surface power density is P(W/m^2), the thermal conductivity of the polymer is k (W/m K), the thermal conductivity of air is k ₀ (W/m K), When the area ratio of air:polymer is A:1-A, and the temperature difference between the wavelength selective transmission layer and the mid-infrared emission layer is dT = T (wavelength selective transmission layer) - T (mid-infrared emission layer), selective heat transmission Since the film thickness d (m) can be determined by Equation 1 below, the area ratio of vacuum or air and the high molecular weight polymer (lattice width in the lattice unit) and the thickness of the selective heat transmission film can be determined according to the allowable surface power density. there is.

[Equation 1]

d = dT·(A·k ₀ + (1-A)·k)/P

Referring to FIG. 1, a selective heat transmission membrane having a lattice-like polymer pattern having a net structure was designed in consideration of process convenience and structural stability. When the thermal conductivity of the polymer is 0.3 W/m K, and the width (w) of the polymer rod is designed to be 1/10 of the period (p), the thermal conductivity of air (0.026 W/m K) and the weighted average As a result, an effective thermal conductivity of 0.078 W/m·K can be obtained, and thus, the same heat shielding effect can be exhibited even with a thickness four times thinner than that of a general polymer layer. In addition, when the thickness (t) of the selective heat transmission film is 5 cm, the energy density transferred from the atmosphere to the mid-infrared ray emitting layer 10 ° C lower than the atmosphere is 70 W / m^2, so conventional color-type radiant cooling Considering that the residual heat energy density absorbed by the mid-infrared radiation layer of the device is tens to hundreds of W/m^2, the present application can exhibit cooling performance similar to or superior to that of the prior art even if the selective heat transmission membrane is designed to be 5 cm or less. there is. In addition, the transmittance of mid-infrared rays in the selective heat transmission membrane is inversely proportional to the area of the polymer pattern for the portion in contact with the wavelength selective transmission layer, and the selective heat transmission membrane of the present application transmits most of the mid-infrared rays through a vacuum or air portion. and may exhibit mid-infrared transmittance of 80% or more, 90% or more, or 95% or more.

In one embodiment of the present application, the mid-infrared radiation layer may absorb mid-infrared rays introduced from the selective heat transmission membrane and emit them to the outside. Specifically, the mid-infrared ray emission layer is designed to absorb all of the mid-infrared rays without reflection at wavelengths of mid-infrared rays and radiate mid-infrared rays to the outside through the selective heat transmission layer and the wavelength selective transmission layer, and induces maximization of black body radiation. The mid-infrared ray emitting layer and the internal object function to be cooled below atmospheric temperature. In addition, when the color-type radiation cooling device of the present application uses the second type of wavelength selective transmission layer, sunlight introduced into the mid-infrared radiation layer should be considered. In this case, the mid-infrared ray emission layer may transmit all incoming sunlight without absorbing it, so that it is reflected to the outside through a lower mirror.

In one embodiment of the present application, the mid-infrared ray emission layer may be in the form of a polymer layer, a multilayer thin film, a nanopattern, or a polymer layer including dispersed nanoparticles, but is not limited thereto.

In one embodiment of the present application, the polymer in the mid-infrared ray emission layer is poly(dimethylsiloxane); PDMS), polyethylene (PE), polystyrene (PS), and polypropylene (PP). ), but may be one or more species selected from the group consisting of, but is not limited thereto. Specifically, the thickness of the polymer layer may be 100 μm to 1000 μm, but is not limited thereto. More specifically, the thickness of the polymer layer is 100 μm to 1000 μm, 200 μm to 1000 μm, 300 μm to 1000 μm, 400 μm to 1000 μm, 500 μm to 1000 μm, 100 μm to 900 μm, 100 μm to 800 μm μm, 400 μm to 900 μm or 300 μm to 800 μm.

Referring to FIG. 1 , the mid-infrared ray emission layer was designed using the same high molecular weight as the selective heat transmission membrane in consideration of manufacturing consistency and process convenience. The mid-infrared emitting layer should be designed to maximize the absorption rate of mid-infrared rays, and when PDMS is used, since most of the mid-infrared rays are absorbed with only a thickness of 500 μm or more, it can be easily manufactured without introducing a vacuum-based process of the prior art. Therefore, if the mid-infrared ray emission layer of the present application is placed in the direction of an object to be cooled, the object can be cooled to a temperature below the external air temperature through heat conduction and convection.

The color type radiation cooling device according to an embodiment of the present application may further include a mirror containing silver (Ag) or aluminum (Al) on the other side of the selective heat transmission film in the mid-infrared ray emission layer. Specifically, when the wavelength selective transmission layer is of the second type, sunlight and mid-infrared rays introduced from the wavelength selective transmission layer are transmitted through the selective heat transmission layer and introduced into the mid-infrared emission layer. At this time, mid-infrared rays are absorbed by the mid-infrared ray emitting layer and then radiated back to the selective heat transmission layer, whereas sunlight is not absorbed and radiated by the mid-infrared ray emitting layer, so it is difficult to implement a cooling function. Accordingly, a mirror containing silver (Ag) or aluminum (Al) may be additionally included at the lower end of the mid-infrared ray emission layer to reflect (transmit) the introduced sunlight back to the outside in order to realize cooling performance. In addition, since the sunlight is a wavelength that is not absorbed by the wavelength selective transmission layer, the color-type radiation cooling device can express color when reflected to the outside.

The color type radiation cooling device according to an embodiment of the present application may further include an antireflection layer between the wavelength selective transmission layer and the selective heat transmission layer. Specifically, when the wavelength selective transmission layer is of the first type, the antireflection layer may allow mid-infrared rays emitted from the mid-infrared emission layer to be transmitted through the wavelength selective transmission layer without reflection. In addition, when the wavelength selective transmission layer is of the second type, the antireflection layer allows mid-infrared rays emitted from the mid-infrared emission layer to be transmitted through the wavelength selective transmission layer without reflection, and sunlight reflected from the mirror It can be transmitted through the wavelength selective transmission layer without absorption and reflection.

In one embodiment of the present application, the antireflection layer may be in the form of a multilayer thin film, a nanopattern, or a polymer layer including dispersed nanoparticles, but is not limited thereto.

In one embodiment of the present application, the antireflection layer is zinc sulfide (ZnS), barium fluoride (BaF ₂ ), zinc selenide (ZnSe), calcium fluoride (CaF ₂ ), sodium chloride ( NaCl), potassium bromide (KBr), potassium chloride (KCl), silver chloride (AgCl), silver bromide (AgBr), cesium iodide (CsI), rubidium chloride (RbCl), magnesium fluoride (MgF ₂ ), diamond, thallium bromide Oxides such as Thallium Bromoiodide (TlBrI; KRS-5), titanium oxide (TiO ₂ ), zircon oxide (ZrO ₂ ), zinc oxide (ZnO), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ) At least one compound selected from the group consisting of nitrides, organic-inorganic pigments, and organic-inorganic dyes is stacked, and the number of layers of the antireflection layer may be smaller than the number of layers of the wavelength selective transmission layer, but is not limited thereto. does not Specifically, when the wavelength selective transmission layer of the first type is used, the antireflection layer may be designed with the same structure as the wavelength selective transmission layer, and since the wavelength of the solar region does not have to be considered, the antireflection layer may have a smaller number than the wavelength selective transmission layer. It can be implemented in layers. Also, when the second type of wavelength selective transmission layer is used, the antireflection layer is designed not to absorb or reflect sunlight, unlike the wavelength selective transmission layer of the second type. Since the antireflection layer shares a substrate with the wavelength selective transmission layer and the compound is laminated, one side of the substrate is a multi-layer thin film that implements color and mid-infrared anti-reflection functions at the same time, and the other side of the substrate has a mid-infrared ray ray without color implementation. It is a structure having a multilayer thin film in which an antireflection function is implemented.

It will be described with reference to FIGS. 3 to 6 below.

A color type radiation cooling device according to an embodiment of the present disclosure may include a wavelength selective transmission layer including 5 layers on one side of a Ge substrate and an antireflection layer including 1 layer on the other side. The color type radiation cooling device of the above embodiment can express red color by including a wavelength selective transmission layer including 5 layers on one side of a Ge substrate (Fig. 3 a and b). The comparative example is an ARC sample, which does not express vivid colors such as RGB, but is a radiation cooling device with excellent radiation cooling performance. The radiation cooling device of the comparative example includes one layer of wavelength selective transmission layer on one side of a Ge substrate and one layer of antireflection layer on the other side of the Ge substrate, and does not develop color (Fig. 4 a and b).

It can be confirmed that the color-type radiation cooling device according to the embodiment of the present application exhibits high reflectance in the red (R) wavelength region, which is the color to be expressed in visible light, and expresses red (R) because the reflectance of other visible light is low. (FIG. 5). In addition, it can be confirmed that the radiation cooling device of Comparative Example exhibits similar reflectance in all visible light, so that no color is developed (FIG. 5).

It can be seen that the color-type radiation cooling device according to the embodiment of the present application and the radiation cooling device of the comparative example have high transmittance and low reflectance in the wavelength range of the mid-infrared ray region, and in particular, very high transmittance and low reflectance in the wavelength region of 8 μm to 13 μm. It can be confirmed that reflectance appears (FIG. 6). Through this, it was confirmed that the color-type radiation cooling device according to the embodiment of the present application can express vivid colors and realize excellent radiation cooling performance.

A second aspect of the present disclosure provides a method for cooling an object using the color radiation cooling device according to the first aspect.

In the first aspect and the second aspect, contents that can be common to each other can be applied to both the first aspect and the second aspect even if the description is omitted.

Referring to FIG. 7 , it can be confirmed that an object can be cooled using the color type radiation cooling device of the present disclosure. Specifically, it was measured whether the radiation cooling performance of the color-type radiation cooling device according to the embodiment of the present application is implemented compared to the radiation cooling device of the comparative example. It was conducted in Seoul on August 14, 2019, and the cooling onset temperature compared to the air temperature of each radiant cooling device was measured for one day. As a result of the measurement, it was confirmed that the color-type radiation cooling device according to the embodiment implemented cooling performance with a similar behavior throughout the day compared to the radiation cooling device of the comparative example. It was confirmed that the cooling expression temperature of the color-type radiation cooling device was superior to that of the comparative example, and it was confirmed that the color-type radiation cooling device according to the embodiment of the present application can express vivid colors and realize excellent radiation cooling performance.

The above description of the present application is for illustrative purposes, and those skilled in the art will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as being included in the scope of the present application.

Claims (20)

delete delete A color-type radiation cooling device comprising a selective heat transmission film between a wavelength selective transmission layer and a mid-infrared radiation layer,
The wavelength selective transmission layer expresses color, the mid-infrared ray emission layer realizes radiation cooling, and the selective heat transmission membrane blocks heat exchange,
The wavelength selective transmission layer is a first type,
Reflecting the first wavelength of the color to be implemented among the incident sunlight, absorbing sunlight other than the first wavelength, and transmitting mid-infrared rays,
The selective heat transmission layer transmits mid-infrared rays and blocks heat transfer from the wavelength selective transmission layer to the mid-infrared emission layer;
The wavelength selective transmission layer is germanium (Ge), zinc sulfide (ZnS), barium fluoride (BaF ₂ ), zinc selenide (ZnSe), calcium fluoride (CaF ₂ ), sodium chloride (NaCl), potassium bromide on the first substrate (KBr), potassium chloride (KCl), silver chloride (AgCl), silver bromide (AgBr), cesium iodide (CsI), rubidium chloride (RbCl), magnesium fluoride (MgF ₂ ), diamond, thallium bromoiodide , TlBrI; KRS-5), titanium oxide (TiO ₂ ), zircon oxide (ZrO ₂ ), zinc oxide (ZnO), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), organic-inorganic pigments and organic-inorganic dyes At least one compound selected from the group consisting of is a laminated form,
The first substrate is glass, quartz, polyethylene (PE), polypropylene (PP), polyimide (PI), polystyrene (PS), polyethylene terephthalate (PET), germanium (Ge), silicon (Si) and gallium arsenic (GaAs) containing one or more compounds selected from the group containing,
Simultaneously implementing color expression and transmission of mid-infrared rays regardless of the area of the wavelength selective transmission layer by the combination of the compound laminated on the first substrate and the first substrate,
Color-type radiant cooling device.
A color-type radiation cooling device comprising a selective heat transmission film between a wavelength selective transmission layer and a mid-infrared radiation layer,
The wavelength selective transmission layer expresses color, the mid-infrared ray emission layer realizes radiation cooling, and the selective heat transmission membrane blocks heat exchange,
The wavelength selective transmission layer is a second form,
Reflecting or transmitting a first wavelength of a color to be implemented among incident sunlight, absorbing sunlight other than the first wavelength, and transmitting mid-infrared rays;
The selective heat transmission layer transmits mid-infrared rays and blocks heat transfer from the wavelength selective transmission layer to the mid-infrared emission layer;
The wavelength selective transmission layer is zinc sulfide (ZnS), barium fluoride (BaF ₂ ), zinc selenide (ZnSe), calcium fluoride (CaF ₂ ), sodium chloride (NaCl), potassium bromide (KBr), chloride Potassium (KCl), silver chloride (AgCl), silver bromide (AgBr), cesium iodide (CsI), rubidium chloride (RbCl), magnesium fluoride (MgF ₂ ), diamond, thallium bromoiodide (TlBrI; KRS- 5) selected from the group consisting of titanium oxide (TiO ₂ ), zircon oxide (ZrO ₂ ), zinc oxide (ZnO), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), organic-inorganic pigments and organic-inorganic dyes It is a laminated form of one or more compounds to be,
The second substrate includes sodium chloride (NaCl), potassium bromide (KBr), potassium chloride (KCl), zinc sulfide (ZnS), silver chloride (AgCl), silver bromide (AgBr), cesium iodide (CsI) and diamond It includes one or more compounds selected from the group
Simultaneously implementing color expression and transmission of mid-infrared rays regardless of the area of the wavelength selective transmission layer by the combination of the compound laminated on the second substrate and the second substrate,
Color-type radiant cooling device.
delete According to claim 3 or 4,
The mid-infrared radiation layer absorbs the mid-infrared rays introduced from the selective heat transmission film and emits them to the outside, the color type radiation cooling device.
According to claim 3 or 4,
Further comprising a mirror containing silver (Ag) or aluminum (Al) on the other side of the selective heat transmission film in the mid-infrared radiation layer, the color type radiation cooling device.
According to claim 3 or 4,
The wavelength selective transmission layer is in the form of a multilayer thin film, a nanopattern or a polymer layer including dispersed nanoparticles, a color type radiation cooling device.
delete delete According to claim 3 or 4,
The selective heat transmission membrane includes at least one selected from the group consisting of vacuum, air, polymer membrane, polymer pattern, and polymer column, color-type radiation cooling device.
According to claim 3 or 4,
The selective heat permeable membrane includes air and polymer patterns,
According to the allowable surface power density, the area ratio of the air and the polymer pattern and the thickness of the selective heat transmission film are determined, the color type radiation cooling device.
According to claim 11,
The polymer pattern is a lattice type including a plurality of lattice units having periods,
The lattice width in the lattice unit is less than 1/10 of the period, the color type radiation cooling device.
According to claim 3 or 4,
The thickness of the selective heat-transmitting film is 5 cm or less, color-type radiation cooling device.
According to claim 3 or 4,
The mid-infrared ray emission layer is in the form of a polymer layer, a multilayer thin film, a polymer layer including nanopatterns or dispersed nanoparticles, a color type radiation cooling device.
According to claim 15,
The polymer is at least one selected from the group consisting of poly(dimethylsiloxane); PDMS), polyethylene (PE), polystyrene (PS) and polypropylene (PP), color type Radiant cooling device.
According to claim 15,
The thickness of the polymer layer is 100 μm to 1000 μm, color type radiation cooling device.
According to claim 3 or 4,
Further comprising an antireflection layer between the wavelength selective transmission layer and the selective heat transmission layer, color type radiation cooling device.
According to claim 18,
The antireflection layer is made of zinc sulfide (ZnS), barium fluoride (BaF ₂ ), zinc selenide (ZnSe), calcium fluoride (CaF ₂ ), sodium chloride (NaCl), potassium bromide (KBr) on the substrate of the wavelength selective transmission layer. , potassium chloride (KCl), silver chloride (AgCl), silver bromide (AgBr), cesium iodide (CsI), rubidium chloride (RbCl), magnesium fluoride (MgF ₂ ), diamond, thallium bromoiodide (TlBrI ; KRS-5), titanium oxide (TiO ₂ ), zircon oxide (ZrO ₂ ), zinc oxide (ZnO), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), organic-inorganic pigments and organic-inorganic dyes One or more compounds selected from the group will be in the form of a layered, color-type radiation cooling device.
A method of cooling an object using the color radiation cooling device according to claim 3 or 4.

Images