WO2018180177A1 - Radiative cooling device and radiative cooling method - Google Patents

Radiative cooling device and radiative cooling method Download PDF

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Publication number
WO2018180177A1
WO2018180177A1 PCT/JP2018/007819 JP2018007819W WO2018180177A1 WO 2018180177 A1 WO2018180177 A1 WO 2018180177A1 JP 2018007819 W JP2018007819 W JP 2018007819W WO 2018180177 A1 WO2018180177 A1 WO 2018180177A1
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Prior art keywords
layer
radiation
light
ultraviolet
reflection layer
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PCT/JP2018/007819
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French (fr)
Japanese (ja)
Inventor
末光真大
齋藤禎
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大阪瓦斯株式会社
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Priority claimed from JP2017218235A external-priority patent/JP6861614B2/en
Application filed by 大阪瓦斯株式会社 filed Critical 大阪瓦斯株式会社
Priority to CN201880021513.7A priority Critical patent/CN110462464B/en
Priority to US16/494,389 priority patent/US11598592B2/en
Publication of WO2018180177A1 publication Critical patent/WO2018180177A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/18—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by applying coatings, e.g. radiation-absorbing, radiation-reflecting; by surface treatment, e.g. polishing
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/26—Reflecting filters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/28—Interference filters

Definitions

  • the present invention comprises an ultraviolet reflection layer that reflects ultraviolet light, a light reflection layer that reflects visible light and infrared light, and an infrared emission layer that emits infrared light, and emits infrared light from the emission surface And a radiation cooling method.
  • Radiation cooling refers to a phenomenon in which a substance reduces its temperature by emitting an electromagnetic wave such as infrared light to the surroundings. If this phenomenon is used, for example, it can be used as a cooling device that cools an object without consuming energy such as electricity.
  • Patent Document 1 an ultraviolet reflection layer of silicon dioxide or hafnium oxide is formed on a solar light reflection layer (light reflection layer) made of silver, and a thickness of silicon dioxide or hafnium oxide is formed on the ultraviolet reflection layer.
  • a radiation cooling device is disclosed which has formed an infrared radiation layer of several ⁇ m.
  • the ultraviolet light contained in the received sunlight is reflected by the ultraviolet reflection layer, and the other light is mainly reflected by the sunlight reflection layer (light reflection layer), It is supposed to escape from that lineage. Also, part of the infrared light contained in the received sunlight and the heat input from the atmosphere, the object to be cooled, etc. are converted to infrared light of a predetermined wavelength range by the infrared radiation layer, and escape to the outside of the system It is supposed to be.
  • the present invention has been made in view of such circumstances, and an object thereof is to provide a radiation cooling apparatus and a radiation cooling method in which absorption of ultraviolet light is suppressed.
  • the characteristic configuration of the radiation cooling device according to the present invention for achieving the above object is A radiation cooling apparatus including an ultraviolet reflection layer that reflects ultraviolet light, a light reflection layer that reflects visible light and infrared light, and an infrared radiation layer that emits infrared light, and emitting infrared light from the radiation surface
  • an ultraviolet reflection layer that reflects ultraviolet light
  • a light reflection layer that reflects visible light and infrared light
  • an infrared radiation layer that emits infrared light
  • the ultraviolet light contained in the light such as sunlight incident from the radiation surface side of the radiation cooling device is reflected by the ultraviolet reflection layer on the radiation surface side and escapes from the system from the radiation surface . Therefore, it can be avoided that ultraviolet light is incident on the infrared radiation layer or the light reflection layer. Further, since it is not necessary to provide a multilayer structure with a film-like layer directly on the light reflecting layer, it is possible to avoid an increase in absorption of ultraviolet light due to surface plasmon resonance in the light reflecting layer. Therefore, according to the above configuration, absorption of ultraviolet light can be suppressed.
  • the term “light” when the term “light” is simply used, the concept of the light includes infrared light, visible light, and ultraviolet light. When these are described in terms of the wavelength of light as an electromagnetic wave, the wavelength includes an electromagnetic wave of 10 nm to 20000 nm.
  • the heat input to the radiation cooling device is converted to infrared radiation in the infrared radiation layer, and is released from the radiation surface to the outside of the system.
  • the light irradiated to the radiation cooling device is reflected, and the heat transfer to the radiation cooling device (for example, the heat transfer from the atmosphere or the cooling object cooled by the radiation cooling device) Heat transfer) can be emitted out of the system as infrared light. That is, it is possible to provide a radiation cooling device in which absorption of ultraviolet light is suppressed.
  • the ultraviolet reflection layer is formed by laminating two or more dielectrics,
  • the dielectric is selected from any of silicon dioxide, aluminum oxide, silicon nitride, zirconium dioxide, titanium dioxide, magnesium oxide, hafnium oxide, aluminum nitride, zinc oxide and niobium pentoxide.
  • dielectric A substance in which dielectric is superior to conductivity is called dielectric.
  • Multilayers of dielectrics of different refractive indices can be used to reflect light of any wavelength.
  • silicon dioxide, aluminum oxide (sapphire), silicon nitride, zirconium dioxide, titanium dioxide, magnesium oxide, hafnium oxide, aluminum nitride, zinc oxide and niobium pentoxide are preferably used.
  • it is preferable to stack two or more types of dielectrics having different refractive indexes because the reflectance of ultraviolet light in the ultraviolet reflective layer is improved. This is because the reflectance of the entire ultraviolet reflection layer is improved by utilizing the interference of the reflected light from the boundaries of the respective dielectrics forming the ultraviolet reflection layer. Therefore, according to the said structure, the radiation cooling device which suppressed absorption of the ultraviolet light can be provided.
  • the layer thickness of the dielectric is less than 200 nm.
  • ultraviolet light can be efficiently reflected by the ultraviolet reflection layer.
  • the wavelength of ultraviolet light is less than about 400 nm, it is because ultraviolet light can be efficiently reflected if it is a half wavelength of the wavelength, that is, less than 200 nm.
  • Ultraviolet light is generally defined as 10 to 400 nm in many cases, and the solar light spectrum contains almost no light at wavelengths shorter than 300 nm. That is, when using a dielectric having a refractive index of about 1 in the wavelength range, about 75 to 100 nm or 150 to 200 nm, and using a dielectric having a refractive index of about 3 in the wavelength range, about 25 to 33 nm or 50 to 50 It will be 66 nm.
  • silicon dioxide, aluminum oxide (sapphire), silicon nitride, zirconium dioxide, titanium dioxide, magnesium oxide, hafnium oxide, aluminum nitride, zinc oxide, and niobium pentoxide have a thickness of several hundred nm and almost have a UV absorption coefficient.
  • the dielectric of the ultraviolet reflection layer to be the radiation surface is selected from any of silicon dioxide, aluminum oxide, silicon nitride, zirconium dioxide, titanium dioxide and niobium pentoxide.
  • Silicon dioxide, aluminum oxide, silicon nitride, zirconium dioxide, titanium dioxide, and niobium pentoxide are less susceptible to hydrolysis by moisture in the environment, and are resistant to oxidation by oxygen in the air and have high weatherability.
  • silicon dioxide, aluminum oxide, zirconium dioxide, titanium dioxide and niobium pentoxide have low oxygen mobility among oxides, and are stable as a material (substance) with little change over time (temporarily) It is for.
  • the infrared radiation layer consists in silicon dioxide.
  • Preferred materials which transmit light and produce infrared radiation of 8000 nm to 20000 nm include silicon dioxide, aluminum oxide, magnesium oxide and hafnium dioxide.
  • silicon dioxide has a large absorption peak near a wavelength of 10000 nm, and efficiently emits infrared radiation of a wavelength of 10000 nm, which is between 8000 nm and 20000 nm.
  • silicon dioxide is preferably used as a material (substance) used for the infrared radiation layer. That is, according to the above configuration, it is possible to avoid receiving heat and generating heat, and efficiently radiate the heat of the radiation cooling device as infrared rays to improve the cooling performance.
  • the thickness of the infrared radiation layer is more than 1 ⁇ m.
  • the thickness of the light reflection layer may be a thickness exceeding 1 ⁇ m, and is formed to 10000 ⁇ m or less in consideration of the economical aspect. In general, when the thickness is 20 ⁇ m to 10000 ⁇ m, the balance between the economic aspect and the technical aspect in terms of production and fabrication is good.
  • the light reflecting layer is made of silver or aluminum.
  • the thickness of the light reflecting layer is greater than 80 nm.
  • the thickness of the light reflection layer may be a thickness exceeding 80 nm, and is formed to 1000 nm or less in consideration of the economical aspect. Usually, when it is formed to a thickness of around 200 nm, it is well balanced in terms of economy, weatherability and durability.
  • the characteristic configuration of the radiation cooling method according to the present invention for achieving the above object is An ultraviolet reflection layer that reflects ultraviolet light, a light reflection layer that reflects visible light and infrared light, an infrared radiation layer that emits infrared light, the ultraviolet reflection layer, the infrared radiation layer, and The point is that the infrared light is emitted from the radiation surface opposite to the surface in contact with the infrared radiation layer of the ultraviolet reflection layer using a radiation cooling device formed by laminating the light reflection layer in order.
  • a further characterizing feature of the radiation cooling method according to the present invention is The radiation surface is directed to the sky, and the radiation surface is directed to radiate from the radiation surface directed to the sky.
  • the radiation cooling device 100 shown in FIG. 1 is a cooling device for obtaining a cooling effect.
  • the radiation cooling device 100 cools an object to be cooled (not shown).
  • the radiation cooling device 100 reflects the light L (for example, sunlight) incident on the radiation cooling device 100, and the heat input to the radiation cooling device 100 (for example, due to heat conduction from an atmosphere of the atmosphere or a cooling object).
  • a cooling effect is realized by converting the heat input into infrared light and emitting it.
  • light refers to an electromagnetic wave having a wavelength of 10 nm to 20000 nm. That is, the light L includes ultraviolet light UV, infrared light IR and visible light VL.
  • the radiation cooling device 100 includes an ultraviolet reflection layer 10 that reflects ultraviolet light UV, a light reflection layer 20 that reflects visible light and infrared light, and infrared light IR. Emitting infrared radiation IR from the radiation surface 40; And the radiation cooling device 100 is laminated
  • the radiation surface 40 is the surface of the ultraviolet reflection layer 10 opposite to the surface in contact with the infrared radiation layer 30.
  • the radiation cooling method includes the ultraviolet reflection layer 10 that reflects ultraviolet light UV, the light reflection layer 20 that reflects visible light and infrared light, and an infrared radiation layer that emits infrared light IR.
  • 30 is stacked in the order of the ultraviolet reflection layer 10, the infrared radiation layer 30, and the light reflection layer 20, and the radiation surface on the opposite side to the surface of the ultraviolet reflection layer 10 in contact with the infrared radiation layer 30 Emit from 40
  • the ultraviolet reflection layer 10 is a layer made of a dielectric, which has an optical structure that reflects ultraviolet light UV and transmits visible light VL and infrared light IR.
  • the ultraviolet reflection layer 10 is formed by laminating two or more types of dielectrics, as shown in FIG.
  • the ultraviolet reflective layer 10 shown in FIG. 2 has a dielectric layer 11 and a dielectric layer 15 stacked on top of each other as a layer made of a dielectric. One surface of the ultraviolet reflection layer 10 is in close contact with the infrared radiation layer 30.
  • the ultraviolet light UV means an electromagnetic wave having a wavelength of 10 nm to 400 nm.
  • the infrared light IR refers to an electromagnetic wave having a wavelength of about 700 nm to 20000 nm.
  • the visible light VL refers to an electromagnetic wave having a wavelength of approximately 400 nm to 700 nm.
  • the dielectric layers of the ultraviolet reflective layer 10 are each in the form of a film of less than 200 nm.
  • This film-like layer can be formed, for example, by the so-called CVD method or sputtering method, and there is no limitation on its formation method.
  • the surface on the opposite side to the surface in contact with the infrared radiation layer 30 of the ultraviolet reflective layer 10, that is, the surface on the side open to the atmosphere is a radiation surface 40 that emits infrared light IR in the radiation cooling device 100.
  • the surface of the dielectric layer on the opposite side (the other end side) to the surface of the ultraviolet reflection layer 10 in contact with the infrared radiation layer 30 is the radiation surface of the layer that is open to the atmosphere. It is.
  • the surface of the dielectric layer on the side of the ultraviolet reflection layer 10 that is open to the atmosphere is the radiation surface 40 of the radiation cooling device 100.
  • the dielectric layer 11 to be the radiation surface 40 is made of a material (material) selected from any of silicon dioxide, aluminum oxide, silicon nitride and zirconium dioxide.
  • FIG. 2 shows the case where the dielectric layer 11 is formed of sapphire as aluminum oxide.
  • the dielectric layer 11 to the dielectric layer 15 in FIG. 2 are illustrated in the case of sapphire, silicon dioxide, sapphire, silicon dioxide and sapphire in this order. Further, in FIG. 2, as a specific example in which the thickness (layer thickness) of the dielectric is less than 200 nm, the thicknesses of the dielectric layer 11 to the dielectric layer 15 are 30 nm, 50 nm, 50 nm, 40 nm, and 40 nm in this order.
  • the case is illustrated. 7 and 8 show the reflectance, the transmittance, and the absorptivity of the ultraviolet reflection layer 10 shown in FIG.
  • the ultraviolet reflection layer 10 has a high absorptivity in a wavelength range around 10000 nm corresponding to the window of the atmosphere, and emits infrared light in a wavelength range around 10000 nm.
  • the infrared radiation layer 30 is a layer that transmits the light L and emits infrared light IR.
  • One surface of the infrared radiation layer 30 is in close contact with the ultraviolet reflection layer 10, and the other surface is in close contact with the light reflection layer 20.
  • “transmits light” or the like the case where part of the light is absorbed and reflected and most of the light is transmitted is included. For example, when 90% or more of the energy of incident light is transmitted, it is simply described as "transmits light”.
  • the infrared radiation layer 30 is connected to the ultraviolet reflection layer 10 and the light reflection layer 20 so as to be thermally conductive. That is, the infrared radiation layer 30 converts the heat energy of its own, the heat input from the ultraviolet reflection layer 10 (heat energy), and the heat input from the light reflection layer 20 (thermal energy) into infrared light IR. Convert and radiate.
  • the infrared radiation layer 30 is made of silicon dioxide which transmits the light L and efficiently radiates infrared light IR around a wavelength of 10000 nm in the window region of the atmosphere between wavelengths 8000 nm and 20000 nm. Become.
  • the infrared radiation layer 30 is formed to have a thickness of more than 1 ⁇ m.
  • the thickness of the infrared radiation layer 30 may be more than 1 ⁇ m, and it is economical to set it to about 10000 ⁇ m or less, and in particular, it is a balance of economic and performance if it is in the range of 20 ⁇ m to 10000 ⁇ m. Is good.
  • FIG. 3 shows the radiation spectrum of the infrared radiation layer 30 when the layer thickness (thickness) of the infrared radiation layer 30 made of silicon dioxide is 1 ⁇ m, 20 ⁇ m, and 100 ⁇ m.
  • the vertical axis indicates the light absorptivity AB of the infrared radiation layer 30, and the horizontal axis indicates the wavelength WL.
  • the 1 ⁇ m infrared radiation layer 30 of silicon dioxide is a film-like layer prepared by sputtering, and the 20 ⁇ m and 100 ⁇ m infrared radiation layer 30 of silicon dioxide is a layer formed by melting and solidification.
  • the absorptivity of light at an arbitrary wavelength is equal to the emissivity of light, so the distribution shown by the absorptivity AB of the infrared emitting layer 30 in FIG. Equal to the distribution of the intensity of the emitted light.
  • the light reflection layer 20 is a layer made of a metal that reflects the light L, and is a layer that functions as a so-called mirror.
  • the light reflection layer 20 is formed of either silver or aluminum as a metal. In the present embodiment, the case where the light reflection layer 20 is silver is described.
  • the light reflecting layer 20 is formed to be thicker than 80 nm.
  • the light reflection layer 20 has a film thickness of 80 nm or less, transmission starts to occur in a wavelength range of wavelength 2000 nm or less, and light reflection performance can not be exhibited.
  • the thickness of the light reflecting layer 20 exceeds 80 nm, transmission of light does not occur, and the reflectance of light does not change. That is, there is no technical upper limit regarding the thickness of the light reflection layer 20.
  • the thickness of the light reflecting layer 20 may be 1 mm or less.
  • the case where the light reflection layer 20 is silver with a thickness of 200 nm is shown as a specific example in the case where the light reflection layer 20 has a thickness exceeding 80 nm.
  • the first embodiment, the second embodiment, and the third embodiment described below are respectively one aspect of the radiation cooling device 100 according to the present embodiment, having the structure shown in FIG. 1.
  • the radiation cooling device 100 is laminated in the order of the ultraviolet reflection layer 10, the infrared radiation layer 30, and the light reflection layer 20 as viewed from the side of the radiation surface 40.
  • Comparative Example 1 and Comparative Example 2 described below are each a conventional radiation cooling device 200 having the structure shown in FIG. 4.
  • the radiation cooling device 200 is stacked in the order of the infrared radiation layer 30, the ultraviolet reflection layer 10, and the light reflection layer 20, as viewed from the radiation surface 40 side.
  • the cooling performances at an ambient temperature of 30 ° C. of the radiation cooling devices 100 of Example 1, Example 2 and Example 3 and the conventional radiation cooling device 200 of Comparative Example 1 and Comparative Example 2 are compared.
  • the radiation surface 40 of the radiation cooling device 100 or the radiation cooling device 200 is directed to the sky (empty, space) The plane 40 is placed vertically upward.
  • sunlight is used as light in an environment where it is incident at an energy of approximately 1000 W / m 2 from the vertical direction of the material. . Sunlight is incident on the radiation cooling device 100 or the radiation cooling device 200 mainly from the radiation surface 40.
  • Table 1 shows the cooling performance in the case of Example 1.
  • Table 2 shows the cooling performance in the case of Example 2.
  • Table 3 shows the cooling performance in the case of Example 3.
  • Table 4 shows the cooling performance in the case of Comparative Example 1.
  • Table 5 shows the cooling performance in the case of Comparative Example 2. The items shown in Tables 1 to 5 are the same.
  • the configuration common to the radiation cooling devices 100 of the first embodiment, the second embodiment and the third embodiment and the conventional radiation cooling devices 200 of the first comparison example and the second comparison example will be described.
  • the light reflecting layer 20 is compared in the following configuration.
  • the light reflecting layers 20 of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 are all made of a silver layer having a thickness of 200 nm.
  • the description of the light reflection layer 20 is omitted below.
  • the infrared radiation layer 30 is compared in the following configuration.
  • the materials (substances) forming the infrared radiation layer 30 of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 are all silicon dioxide.
  • the thickness of the infrared radiation layer 30 is 1 ⁇ m, 10 ⁇ m, 20 ⁇ m, 100 ⁇ m, 1000 ⁇ m, 10000 ⁇ m, 100000 ⁇ m in each of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 Compare
  • the infrared radiation layer 30 of silicon dioxide of 1 ⁇ m and 10 ⁇ m is a film-like layer produced by sputtering.
  • the infrared radiation layer 30 of silicon dioxide of 20 ⁇ m, 100 ⁇ m, 1000 ⁇ m, 10000 ⁇ m and 100000 ⁇ m is a layer formed by melting and solidification.
  • the description of the infrared radiation layer 30 is omitted below.
  • different component parts of Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2 will be described.
  • the radiation cooling device 100 has the following configuration.
  • the ultraviolet reflection layer 10 is formed by laminating the dielectric layer 11 to the dielectric layer 15 as a layer made of a dielectric.
  • the dielectric layer 11 to the dielectric layer 15 are respectively made of sapphire, silicon dioxide, sapphire, silicon dioxide and sapphire.
  • the thicknesses of the dielectric layer 11 to the dielectric layer 15 are 30 nm, 50 nm, 50 nm, 40 nm, and 40 nm, respectively.
  • the radiation cooling device 100 of the second embodiment has the following configuration.
  • the second embodiment is different from the first embodiment in the laminated structure of the ultraviolet reflective layer 10.
  • the ultraviolet reflective layer 10 is provided with dielectric layers 51 to 66 as dielectric layers as shown in FIG.
  • the dielectric layer 51 to the dielectric layer 66 are formed by alternately stacking 16 layers of silicon dioxide and titanium dioxide, respectively.
  • the thicknesses of the dielectric layer 51 to the dielectric layer 66 are 100 nm, 33 nm, 65 nm, 13 nm, 80 nm, 37 nm, 23 nm, 46 nm, 106 nm, 106 nm, 172 nm, 172 nm, 104 nm, 175 nm, and 103 nm respectively.
  • the ultraviolet reflective layer 10 includes dielectric layers 71 to 74 as dielectric layers.
  • the dielectric layer 71 to the dielectric layer 74 are formed by alternately stacking four layers of silicon dioxide and niobium pentoxide in order.
  • the thicknesses of the dielectric layer 71 to the dielectric layer 74 are 111 nm, 25 nm, 56 nm, and 29 nm, respectively.
  • the ultraviolet reflection layer 10 has a high absorptivity in a wavelength range around 10000 nm corresponding to the window of the atmosphere, and emits infrared light in a wavelength range around 10000 nm.
  • the radiation cooling device 200 of Comparative Example 1 includes the ultraviolet reflective layer 10 having the same laminated structure as that of Example 1.
  • the radiation cooling device 200 of Comparative Example 1 differs from the case of Example 1 in the position where the ultraviolet reflective layer 10 is disposed.
  • the radiation cooling device 200 of Comparative Example 2 includes the ultraviolet reflective layer 10 having the same laminated structure as that of Example 2.
  • the radiation cooling device 200 of Comparative Example 2 differs from the case of Example 2 in the position where the ultraviolet reflective layer 10 is disposed.
  • P1 to P4 in Tables 1 to 5 show the following characteristics of the radiation cooling device 100 or the radiation cooling device 200.
  • t thickness of infrared radiation layer 30 ( ⁇ m)
  • P1 Density of energy of radiation (W / m 2 )
  • P2 Density of energy input from sunlight (W / m 2 )
  • P3 Energy density of heat input from atmosphere (atmosphere) (W / m 2 )
  • P4 Energy density of cooling capacity (W / m 2 )
  • T Equilibrium temperature (° C.) of radiation cooling device 100 or radiation cooling device 200
  • the above-mentioned "density” means the density of the in and out of the energy with respect to the area of the surface of radiation surface 40.
  • P2 means the energy which was not reflected by radiation cooling device 100 or radiation cooling device 200 among the energy of the sunlight which injected with energy of about 1000 W / m 2 .
  • the value of P4 is a value obtained by subtracting the sum of the values of P2 and P3 from the value of P1. The values of P1 and P3 are calculated assuming that the radiation angle with respect to the radiation surface 40 is 60 degrees.
  • the radiation cooling devices 100 of Example 1, Example 2 and Example 3 have a higher cooling capacity than the radiation cooling devices 200 of Comparative Example 1 and Comparative Example 2. . Therefore, rather than laminating the infrared radiation layer 30, the ultraviolet reflection layer 10, and the light reflection layer 20 in order from the side of the radiation surface 40 as in the radiation cooling device 200, as in the radiation cooling device 100, It can be judged that the cooling ability is higher when the ultraviolet reflective layer 10, the infrared radiation layer 30, and the light reflective layer 20 are laminated in order as viewed from the radiation surface 40 side. That is, the difference in cooling capacity between the radiation cooling device 100 according to the present embodiment and the conventional radiation cooling device 200 is that absorption of ultraviolet light is suppressed in the case of the radiation cooling device 100 according to the present embodiment. It is believed that there is.
  • the thickness of the infrared radiation layer 30 exhibits good cooling performance even when reaching 100,000 ⁇ m, and the thickness of the infrared radiation layer 30 exhibits good cooling performance even when it exceeds 100,000 ⁇ m. .
  • the thickness of the infrared radiation layer 30 is sufficient if 100,000 ⁇ m.
  • the layer which consists of a dielectric of the ultraviolet reflective layer 10 is five layers or the case of 16 layers was illustrated in the said embodiment, the layer which consists of a dielectric of the ultraviolet reflective layer 10 is a layer of these laminations It is not limited to the number.
  • the layer made of the dielectric of the ultraviolet reflective layer 10 may have one or more, preferably two or more different dielectrics. Further, the number of layers of the dielectric of the ultraviolet reflective layer 10 may be even or odd.
  • emission surface 40 in the ultraviolet reflective layer 10 was silicon dioxide or aluminum oxide was illustrated.
  • the dielectric layer having the emitting surface 40 may be silicon nitride, zirconium dioxide or titanium dioxide.
  • the layer which consists of a dielectric in the ultraviolet reflective layer 10 is silicon dioxide, aluminum oxide, or titanium dioxide was illustrated.
  • the material (substance) for forming the dielectric layer in the ultraviolet reflective layer 10 may be silicon nitride, zirconium dioxide, titanium dioxide, magnesium oxide, hafnium oxide, aluminum nitride, zinc oxide, niobium pentoxide .
  • the combination of the material (substance) which forms each layer which consists of a dielectric in the ultraviolet reflective layer 10 is not restricted to the range as described in the said embodiment.
  • the relationship between the wavelength and the absorptivity with respect to Tempax that is, the absorptivity of Tempax (thick solid line), the absorptivity in the case where Tempax and silver as light reflecting layer 20 are laminated (dotted-dotted line Absorptivity (thin solid line) in the case where the ultraviolet ray reflection layer of Example 1, the Tempax and the silver as the light reflection layer 20 are laminated in the form of the present invention, and the ultraviolet ray reflection layer of Example 1 and Tempax
  • the absorptivity when laminated (two-dot chain line), and the absorptivity (thin broken line) when Tempacx, the ultraviolet reflection layer of Example 1 and silver as the light reflection layer 20 are laminated in a conventional form, and , The absorption rate of silver (thick broken line) respectively.
  • the present invention is applicable to a radiation cooling device and a radiation cooling method in which absorption of ultraviolet light is suppressed.
  • UV reflective layer 11 dielectric layer (dielectric, UV reflective layer) 12: Dielectric layer (dielectric, ultraviolet reflection layer) 13: Dielectric layer (dielectric, ultraviolet reflection layer) 14: Dielectric layer (dielectric, ultraviolet reflection layer) 15: Dielectric layer (dielectric, ultraviolet reflection layer) 20: Light reflecting layer (dielectric, ultraviolet reflecting layer) 30: infrared radiation layer 40: radiation surface 51: dielectric layer (dielectric, ultraviolet reflection layer) 52: Dielectric layer (dielectric, ultraviolet reflection layer) 53: Dielectric layer (dielectric, ultraviolet reflection layer) 54: Dielectric layer (dielectric, ultraviolet reflection layer) 55: Dielectric layer (dielectric, ultraviolet reflective layer) 56: Dielectric layer (dielectric, ultraviolet reflective layer) 57: Dielectric layer (dielectric, ultraviolet reflective layer) 58: Dielectric layer (dielectric, ultraviolet reflection layer) 59: Dielectric layer (dielectric, ultraviolet reflection layer) 60: Dielectric layer (dielectric, ultraviolet reflection layer) 61: Dielectric layer (dielectric, ultraviolet reflection

Abstract

Provided are a radiative cooling device and a radiative cooling method, wherein absorption of ultraviolet light is suppressed. This radiative cooling device 100 is provided with an ultraviolet reflection layer 10 that reflects ultraviolet light UV, a light reflection layer 20 that reflects visible light and infrared light, and an infrared radiation layer 30 that radiates infrared light IR. This radiative cooling device 100 radiates infrared light IR from a radiation surface 40, and is obtained by sequentially laminating the ultraviolet reflection layer 10, the infrared radiation layer 30 and the light reflection layer 20 in this order when viewed from the radiation surface 40 side.

Description

放射冷却装置および放射冷却方法Radiation cooling device and radiation cooling method
　本発明は、紫外光を反射する紫外反射層と、可視光及び赤外光を反射する光反射層と、赤外光を放射する赤外放射層とを備え、放射面から赤外光を放射する放射冷却装置および放射冷却方法に関する。 The present invention comprises an ultraviolet reflection layer that reflects ultraviolet light, a light reflection layer that reflects visible light and infrared light, and an infrared emission layer that emits infrared light, and emits infrared light from the emission surface And a radiation cooling method.
　放射冷却とは、物質が周囲に赤外線などの電磁波を放射することでその温度が下がる現象のことを言う。この現象を利用すれば、たとえば、電気などのエネルギーを消費せずに物を冷やす冷却装置として利用することができる。 Radiation cooling refers to a phenomenon in which a substance reduces its temperature by emitting an electromagnetic wave such as infrared light to the surroundings. If this phenomenon is used, for example, it can be used as a cooling device that cools an object without consuming energy such as electricity.
　特許文献１には、銀でなる太陽光反射層（光反射層）の上に二酸化ケイ素や酸化ハフニウムの紫外反射層を形成し、当該紫外反射層の上に二酸化ケイ素および酸化ハフニウムで成る厚さ数μｍの赤外線放射層を形成した放射冷却装置が開示されている。 In Patent Document 1, an ultraviolet reflection layer of silicon dioxide or hafnium oxide is formed on a solar light reflection layer (light reflection layer) made of silver, and a thickness of silicon dioxide or hafnium oxide is formed on the ultraviolet reflection layer. A radiation cooling device is disclosed which has formed an infrared radiation layer of several μm.
　この特許文献１の放射冷却装置は、受光した太陽光に含まれる紫外光は紫外反射層で反射し、また、その他の光は、主に太陽光反射層（光反射層）で反射して、その系外に逃がすようになっている。また、受光した太陽光に含まれる赤外光の一部と、雰囲気や冷却対象物などからの入熱は、赤外線放射層により所定の波長域の赤外光に変換し、その系外に逃がすようになっている。 In the radiation cooling device of Patent Document 1, the ultraviolet light contained in the received sunlight is reflected by the ultraviolet reflection layer, and the other light is mainly reflected by the sunlight reflection layer (light reflection layer), It is supposed to escape from that lineage. Also, part of the infrared light contained in the received sunlight and the heat input from the atmosphere, the object to be cooled, etc. are converted to infrared light of a predetermined wavelength range by the infrared radiation layer, and escape to the outside of the system It is supposed to be.
米国特許出願公開第２０１５／０３３８１７５号明細書US Patent Application Publication No. 2015/0338175
　上記特許文献１が開示する従来の放射冷却装置は、太陽光を受光した際に、赤外線放射層や太陽光反射層（光反射層）に太陽光に含まれる紫外光が吸収される場合がある。また、銀のような金属の直上に、膜状の層による多層構造を備えると、太陽光反射層（光反射層）において当該多層構造による表面プラズモン共鳴により紫外光の吸収が増幅される場合がある。
　そのため、従来の放射冷却装置では、十分な冷却性能が得られない場合があり、改善が望まれる。 In the conventional radiation cooling device disclosed in Patent Document 1 described above, when light is received, ultraviolet light contained in sunlight may be absorbed by the infrared radiation layer or the sunlight reflection layer (light reflection layer). . In addition, when a multilayer structure of film-like layers is provided directly on a metal such as silver, absorption of ultraviolet light may be amplified by surface plasmon resonance by the multilayer structure in the solar light reflection layer (light reflection layer). is there.
Therefore, in the conventional radiation cooling device, sufficient cooling performance may not be obtained, and improvement is desired.
　本発明は、かかる実状に鑑みて為されたものであって、その目的は、紫外光の吸収を抑制した放射冷却装置および放射冷却方法を提供することにある。 The present invention has been made in view of such circumstances, and an object thereof is to provide a radiation cooling apparatus and a radiation cooling method in which absorption of ultraviolet light is suppressed.
　上記目的を達成するための本発明に係る放射冷却装置の特徴構成は、
　紫外光を反射する紫外反射層と、可視光及び赤外光を反射する光反射層と、赤外光を放射する赤外放射層とを備え、放射面から赤外光を放射する放射冷却装置において、
　前記放射面の側から見て、前記紫外反射層、前記赤外放射層、および前記光反射層の順に積層して成る点にある。 The characteristic configuration of the radiation cooling device according to the present invention for achieving the above object is
A radiation cooling apparatus including an ultraviolet reflection layer that reflects ultraviolet light, a light reflection layer that reflects visible light and infrared light, and an infrared radiation layer that emits infrared light, and emitting infrared light from the radiation surface In
When viewed from the side of the radiation surface, the UV reflection layer, the infrared radiation layer, and the light reflection layer are sequentially stacked.
　上記構成によれば、放射冷却装置の放射面の側から入射する太陽光などの光に含まれる紫外光は、放射面の側にある紫外反射層で反射され、放射面から系外へ逃がされる。そのため紫外光が赤外放射層や光反射層に入射することを回避することができる。また、光反射層の直上に、膜状の層による多層構造を設けることを要しないため、光反射層における表面プラズモン共鳴による紫外光の吸収増加を回避することができる。したがって、上記構成によれば、紫外光の吸収を抑制することができる。
　なお、本明細書の記載において、単に光と称する場合、当該光の概念には赤外光、可視光、紫外光を含む。これらを電磁波としての光の波長で述べると、その波長が１０ｎｍから２００００ｎｍの電磁波を含む。 According to the above configuration, the ultraviolet light contained in the light such as sunlight incident from the radiation surface side of the radiation cooling device is reflected by the ultraviolet reflection layer on the radiation surface side and escapes from the system from the radiation surface . Therefore, it can be avoided that ultraviolet light is incident on the infrared radiation layer or the light reflection layer. Further, since it is not necessary to provide a multilayer structure with a film-like layer directly on the light reflecting layer, it is possible to avoid an increase in absorption of ultraviolet light due to surface plasmon resonance in the light reflecting layer. Therefore, according to the above configuration, absorption of ultraviolet light can be suppressed.
In the description of the present specification, when the term “light” is simply used, the concept of the light includes infrared light, visible light, and ultraviolet light. When these are described in terms of the wavelength of light as an electromagnetic wave, the wavelength includes an electromagnetic wave of 10 nm to 20000 nm.
　また、上記光に含まれる、紫外光以外の光は、光反射層で反射され、放射面から系外へ逃がされる。そして、放射冷却装置への入熱は、赤外放射層で赤外線に変換されて、放射面から系外へ逃がされる。
　このように、上記構成によれば、放射冷却装置へ照射される光を反射し、また、放射冷却装置への伝熱（例えば、大気からの伝熱や、放射冷却装置が冷却する冷却対象物からの伝熱）を赤外光として系外へ放射することができる。
　すなわち、紫外光の吸収を抑制した放射冷却装置を提供することができる。 Further, light other than ultraviolet light contained in the light is reflected by the light reflection layer and escapes from the radiation surface to the outside of the system. Then, the heat input to the radiation cooling device is converted to infrared radiation in the infrared radiation layer, and is released from the radiation surface to the outside of the system.
As described above, according to the above configuration, the light irradiated to the radiation cooling device is reflected, and the heat transfer to the radiation cooling device (for example, the heat transfer from the atmosphere or the cooling object cooled by the radiation cooling device) Heat transfer) can be emitted out of the system as infrared light.
That is, it is possible to provide a radiation cooling device in which absorption of ultraviolet light is suppressed.
　本発明に係る放射冷却装置の更なる特徴構成は、
　前記紫外反射層は、二種以上の誘電体を積層して成り、
　前記誘電体は、二酸化ケイ素、酸化アルミニウム、窒化ケイ素、二酸化ジルコニウム、二酸化チタン、酸化マグネシウム、酸化ハフニウム、窒化アルミニウム、酸化亜鉛、五酸化ニオブのいずれかから選択される点にある。 Further features of the radiation cooling device according to the invention are:
The ultraviolet reflection layer is formed by laminating two or more dielectrics,
The dielectric is selected from any of silicon dioxide, aluminum oxide, silicon nitride, zirconium dioxide, titanium dioxide, magnesium oxide, hafnium oxide, aluminum nitride, zinc oxide and niobium pentoxide.
　導電性よりも誘電性の方が優位な物質のことを誘電体という。屈折率の異なる誘電体を多層重ねると任意の波長の光を反射させられる。これら誘電体としては、二酸化ケイ素、酸化アルミニウム（サファイア）、窒化ケイ素、二酸化ジルコニウム、二酸化チタン、酸化マグネシウム、酸化ハフニウム、窒化アルミニウム、酸化亜鉛、五酸化ニオブを用いることが好ましい。
　さらに、先述の通り屈折率の異なる二種以上の誘電体を積層すると、紫外反射層での紫外光の反射率が向上するため好ましい。紫外反射層を形成するそれぞれの誘電体の境界からの反射光の干渉を利用することで紫外反射層全体の反射率が向上するためである。
　したがって、上記構成によれば、紫外光の吸収を抑制した放射冷却装置を提供することができる。 A substance in which dielectric is superior to conductivity is called dielectric. Multilayers of dielectrics of different refractive indices can be used to reflect light of any wavelength. As these dielectrics, silicon dioxide, aluminum oxide (sapphire), silicon nitride, zirconium dioxide, titanium dioxide, magnesium oxide, hafnium oxide, aluminum nitride, zinc oxide and niobium pentoxide are preferably used.
Furthermore, as described above, it is preferable to stack two or more types of dielectrics having different refractive indexes, because the reflectance of ultraviolet light in the ultraviolet reflective layer is improved. This is because the reflectance of the entire ultraviolet reflection layer is improved by utilizing the interference of the reflected light from the boundaries of the respective dielectrics forming the ultraviolet reflection layer.
Therefore, according to the said structure, the radiation cooling device which suppressed absorption of the ultraviolet light can be provided.
　本発明に係る放射冷却装置の更なる特徴構成は、
　前記誘電体の層厚が、２００ｎｍ未満である点にある。 Further features of the radiation cooling device according to the invention are:
The layer thickness of the dielectric is less than 200 nm.
　上記構成によれば、紫外反射層で効率良く紫外光を反射することができる。紫外光の波長は約４００ｎｍ未満であるが、当該波長の半波長、すなわち２００ｎｍ未満の厚みとすると、紫外光を効率よく反射することができるためである。 According to the above configuration, ultraviolet light can be efficiently reflected by the ultraviolet reflection layer. Although the wavelength of ultraviolet light is less than about 400 nm, it is because ultraviolet light can be efficiently reflected if it is a half wavelength of the wavelength, that is, less than 200 nm.
　具体的に述べると、紫外線の反射を増やすためには、反射させたい紫外線の波長の４分の１波長程度、あるいは２分の１波長程度の光路長が得られる厚みの膜を多数積層させるのが望ましい。
　紫外線は一般的に１０から４００ｎｍと定義されることが多く、太陽光スペクトルは３００ｎｍよりも短波長側の光が殆ど含まれない。つまり、屈折率が当該波長域で１程度の誘電体を用いる場合は７５から１００ｎｍ程度あるいは１５０から２００ｎｍ、屈折率が当該波長域で３程度の誘電体を用いる場合は２５から３３ｎｍ程度あるいは５０から６６ｎｍとなる。 Specifically, in order to increase the reflection of ultraviolet light, it is necessary to stack a number of films having a thickness capable of obtaining an optical path length of about a quarter wavelength or about a half wavelength of the wavelength of the ultraviolet light to be reflected. Is desirable.
Ultraviolet light is generally defined as 10 to 400 nm in many cases, and the solar light spectrum contains almost no light at wavelengths shorter than 300 nm. That is, when using a dielectric having a refractive index of about 1 in the wavelength range, about 75 to 100 nm or 150 to 200 nm, and using a dielectric having a refractive index of about 3 in the wavelength range, about 25 to 33 nm or 50 to 50 It will be 66 nm.
　すなわち、二酸化ケイ素、酸化アルミニウム（サファイア）、窒化ケイ素、二酸化ジルコニウム、二酸化チタン、酸化マグネシウム、酸化ハフニウム、窒化アルミニウム、酸化亜鉛、五酸化ニオブは、数百ｎｍの膜厚で紫外線の吸収率が殆どない紫外線反射層に適した誘電体であるが、このような誘電体により効率良く紫外光を反射するためには、これら誘電体の層厚を、２００ｎｍ未満とするのが好ましいのである。 That is, silicon dioxide, aluminum oxide (sapphire), silicon nitride, zirconium dioxide, titanium dioxide, magnesium oxide, hafnium oxide, aluminum nitride, zinc oxide, and niobium pentoxide have a thickness of several hundred nm and almost have a UV absorption coefficient. However, in order to efficiently reflect ultraviolet light by such a dielectric, it is preferable to set the layer thickness of these dielectrics to less than 200 nm.
　本発明に係る放射冷却装置の更なる特徴構成は、
　前記放射面となる前記紫外反射層の前記誘電体は、二酸化ケイ素、酸化アルミニウム、窒化ケイ素、二酸化ジルコニウム、二酸化チタン、五酸化ニオブのいずれかから選択される点にある。 Further features of the radiation cooling device according to the invention are:
The dielectric of the ultraviolet reflection layer to be the radiation surface is selected from any of silicon dioxide, aluminum oxide, silicon nitride, zirconium dioxide, titanium dioxide and niobium pentoxide.
　上記構成によれば、外部環境に直接に接する放射面の対候性を向上させることができる。二酸化ケイ素、酸化アルミニウム、窒化ケイ素、二酸化ジルコニウム、二酸化チタン、五酸化ニオブは、環境中の水分で加水分解を生じにくく、また、大気中の酸素による酸化に強く、対候性が高いためである。また、二酸化ケイ素、酸化アルミニウム、二酸化ジルコニウム、二酸化チタン、五酸化ニオブは、酸化物の中では酸素移動性が低く、経時的（継時的）な変化が少なく材料（物質）として安定しているためである。 According to the above configuration, the weatherability of the radiation surface in direct contact with the external environment can be improved. Silicon dioxide, aluminum oxide, silicon nitride, zirconium dioxide, titanium dioxide, and niobium pentoxide are less susceptible to hydrolysis by moisture in the environment, and are resistant to oxidation by oxygen in the air and have high weatherability. . In addition, silicon dioxide, aluminum oxide, zirconium dioxide, titanium dioxide and niobium pentoxide have low oxygen mobility among oxides, and are stable as a material (substance) with little change over time (temporarily) It is for.
　本発明に係る放射冷却装置の更なる特徴構成は、
　前記赤外放射層は、二酸化ケイ素で成る点にある。 Further features of the radiation cooling device according to the invention are:
The infrared radiation layer consists in silicon dioxide.
　放射冷却においては、いわゆる大気の窓の領域（光の波長８０００ｎｍから２００００ｎｍの領域）における放射の効率を高めると、冷却効率が向上する。放射冷却装置が放射した赤外線が大気に吸収されて、再度放射冷却装置に伝熱することが回避できるためである。
　光を透過し、８０００ｎｍから２００００ｎｍの赤外線の放射を生じる好ましい材料（物質）としては、二酸化ケイ素、酸化アルミニウム、酸化マグネシウム、二酸化ハフニウムがある。特に、二酸化ケイ素は、波長１００００ｎｍ付近に大きな吸収ピークを有しており、波長８０００ｎｍから２００００ｎｍの間である波長１００００ｎｍの赤外線を効率よく放射する。そのため、赤外放射層に用いる材料（物質）としては、二酸化ケイ素を用いることが好ましい。
　すなわち、上記構成によれば、光を受けて発熱することを回避し、また、放射冷却装置の熱を効率よく赤外線として放射して、冷却性能を向上させることができる。 In radiation cooling, if the efficiency of radiation in the so-called atmospheric window region (the wavelength region of 8000 nm to 20000 nm of light) is increased, the cooling efficiency is improved. This is because it is possible to prevent the infrared radiation emitted by the radiation cooling device from being absorbed by the atmosphere and transferred to the radiation cooling device again.
Preferred materials which transmit light and produce infrared radiation of 8000 nm to 20000 nm include silicon dioxide, aluminum oxide, magnesium oxide and hafnium dioxide. In particular, silicon dioxide has a large absorption peak near a wavelength of 10000 nm, and efficiently emits infrared radiation of a wavelength of 10000 nm, which is between 8000 nm and 20000 nm. Therefore, silicon dioxide is preferably used as a material (substance) used for the infrared radiation layer.
That is, according to the above configuration, it is possible to avoid receiving heat and generating heat, and efficiently radiate the heat of the radiation cooling device as infrared rays to improve the cooling performance.
　本発明に係る放射冷却装置の更なる特徴構成は、
　前記赤外放射層の厚みが１μｍを超える厚みである点にある。 Further features of the radiation cooling device according to the invention are:
The thickness of the infrared radiation layer is more than 1 μm.
　上記構成によれば、赤外放射層において、十分な赤外放射能が得られ、高い冷却性能が得られる。
　なお、光反射層の厚みは、１μｍを超える厚みであればよく、経済的側面を考慮して１００００μｍ以下に形成される。通常は２０μｍから１００００μｍの厚みに形成すると、経済的側面と、制作上ないし作製上の技術的側面の点でバランスが良い。 According to the above configuration, sufficient infrared radiation can be obtained in the infrared radiation layer, and high cooling performance can be obtained.
In addition, the thickness of the light reflection layer may be a thickness exceeding 1 μm, and is formed to 10000 μm or less in consideration of the economical aspect. In general, when the thickness is 20 μm to 10000 μm, the balance between the economic aspect and the technical aspect in terms of production and fabrication is good.
　本発明に係る放射冷却装置の更なる特徴構成は、
　前記光反射層が、銀またはアルミニウムで成る点にある。 Further features of the radiation cooling device according to the invention are:
The light reflecting layer is made of silver or aluminum.
　上記構成によれば、広い波長域で高い反射率を得て、光を受光した場合に発熱を回避することができる。 According to the above configuration, high reflectance can be obtained in a wide wavelength range, and heat generation can be avoided when light is received.
　本発明に係る放射冷却装置の更なる特徴構成は、
　前記光反射層の厚みが８０ｎｍを超える厚みである点にある。 Further features of the radiation cooling device according to the invention are:
The thickness of the light reflecting layer is greater than 80 nm.
　上記構成によれば、光反射層において波長２０００ｎｍ以下で透過を生ずることなく可視光及び赤外光を反射することができる。
　なお、光反射層の厚みは、８０ｎｍを超える厚みであればよく、経済的側面を考慮して１０００ｎｍ以下に形成される。通常は２００ｎｍ前後の厚みに形成すると、経済面と、対候性および耐久性の点でバランスが良い。 According to the above configuration, it is possible to reflect visible light and infrared light without transmission at a wavelength of 2000 nm or less in the light reflection layer.
In addition, the thickness of the light reflection layer may be a thickness exceeding 80 nm, and is formed to 1000 nm or less in consideration of the economical aspect. Usually, when it is formed to a thickness of around 200 nm, it is well balanced in terms of economy, weatherability and durability.
　上記目的を達成するための本発明に係る放射冷却方法の特徴構成は、
　紫外光を反射する紫外反射層と、可視光及び赤外光を反射する光反射層と、赤外光を放射する赤外放射層とを、前記紫外反射層、前記赤外放射層、および前記光反射層の順に積層して成る放射冷却装置を用いて、前記赤外光を前記紫外反射層の前記赤外放射層と接する面とは反対側の放射面から放射する点にある。 The characteristic configuration of the radiation cooling method according to the present invention for achieving the above object is
An ultraviolet reflection layer that reflects ultraviolet light, a light reflection layer that reflects visible light and infrared light, an infrared radiation layer that emits infrared light, the ultraviolet reflection layer, the infrared radiation layer, and The point is that the infrared light is emitted from the radiation surface opposite to the surface in contact with the infrared radiation layer of the ultraviolet reflection layer using a radiation cooling device formed by laminating the light reflection layer in order.
　上記構成によれば、上述の放射冷却装置を用いた場合と同様の効果を得ることができる。 According to the above configuration, it is possible to obtain the same effect as in the case of using the above-described radiation cooling device.
　本発明に係る放射冷却方法の更なる特徴構成は、
　前記放射面を空に向け、当該空に向けた放射面から放射する点にある。 A further characterizing feature of the radiation cooling method according to the present invention is
The radiation surface is directed to the sky, and the radiation surface is directed to radiate from the radiation surface directed to the sky.
　上記構成によれば、放射面から系外へ逃がされる赤外線を空に向けて放射し、空、すなわち宇宙に対して放出することができる。したがって、放射した赤外線が大気層に吸収されることを抑制し、冷却性能を向上することができる。 According to the above-mentioned configuration, it is possible to radiate infrared radiation, which is released from the radiation surface to the outside of the system, toward the sky and emit it to the sky, that is, the universe. Therefore, it is possible to suppress the absorption of the emitted infrared radiation into the atmosphere layer and to improve the cooling performance.
は、放射冷却装置の構成を説明する図である。These are the figures explaining the composition of a radiation cooling device. は、紫外反射層の構成を説明する図である。These are figures explaining the structure of an ultraviolet reflective layer. は、異なる層厚の赤外放射層の放射スペクトルを示す図である。These are figures which show the radiation spectrum of the infrared radiation layer of different layer thickness. は、従来の放射冷却装置の構成を説明する図である。These are figures explaining the structure of the conventional radiation cooling device. は、紫外反射層の別の構成を説明する図である。These are figures explaining another structure of an ultraviolet reflective layer. は、紫外反射層の更に別の構成を説明する図である。These are figures explaining the further another structure of an ultraviolet reflective layer. は、紫外反射層の反射率、透過率、吸収率を示す図である。These are figures which show the reflectance of the ultraviolet reflective layer, the transmittance | permeability, and an absorptivity. は、紫外反射層の反射率、透過率、吸収率を示す図である。These are figures which show the reflectance of the ultraviolet reflective layer, the transmittance | permeability, and an absorptivity. は、別の構成の紫外反射層の反射率、透過率、吸収率を示す図である。These are figures which show the reflectance of the ultraviolet reflective layer of another structure, the transmittance | permeability, and an absorptivity. は、別の構成の紫外反射層の反射率、透過率、吸収率を示す図である。These are figures which show the reflectance of the ultraviolet reflective layer of another structure, the transmittance | permeability, and an absorptivity. は、テンパックスに関する波長と吸収率との関係を示す図である。These are figures which show the relationship of the wavelength and absorption factor regarding Tempax.
〔実施形態の説明〕
　図面に基づいて、本発明の実施形態に係る放射冷却装置１００および放射冷却方法について説明する。
　図１に示す放射冷却装置１００は、冷却効果を得るための冷却装置である。たとえば、放射冷却装置１００は、冷却対象物（図示せず）を冷却する。 [Description of the embodiment]
A radiation cooling device 100 and a radiation cooling method according to an embodiment of the present invention will be described based on the drawings.
The radiation cooling device 100 shown in FIG. 1 is a cooling device for obtaining a cooling effect. For example, the radiation cooling device 100 cools an object to be cooled (not shown).
　放射冷却装置１００は、放射冷却装置１００に入射した光Ｌ（たとえば、太陽光）を反射し、また、放射冷却装置１００への入熱（例えば、大気の雰囲気や冷却対象物からの熱伝導による入熱）を赤外線に変換して放射することで、冷却効果を実現する。
　なお、本実施形態において光とは、その波長が１０ｎｍから２００００ｎｍの電磁波のことを言う。つまり、光Ｌには、紫外光ＵＶ、赤外光ＩＲおよび可視光ＶＬが含まれる。 The radiation cooling device 100 reflects the light L (for example, sunlight) incident on the radiation cooling device 100, and the heat input to the radiation cooling device 100 (for example, due to heat conduction from an atmosphere of the atmosphere or a cooling object). A cooling effect is realized by converting the heat input into infrared light and emitting it.
In the present embodiment, light refers to an electromagnetic wave having a wavelength of 10 nm to 20000 nm. That is, the light L includes ultraviolet light UV, infrared light IR and visible light VL.
　本実施形態に係る放射冷却装置１００は、図１に示すように、紫外光ＵＶを反射する紫外反射層１０と、可視光及び赤外光を反射する光反射層２０と、赤外光ＩＲを放射する赤外放射層３０とを備え、放射面４０から赤外光ＩＲを放射する。
　そして、放射冷却装置１００は、放射面４０の側から見て、紫外反射層１０、赤外放射層３０、および光反射層２０の順に積層されて成る。
　なお、放射面４０とは、本実施形態においては、紫外反射層１０における、赤外放射層３０と接する面とは反対側の面である。 As shown in FIG. 1, the radiation cooling device 100 according to the present embodiment includes an ultraviolet reflection layer 10 that reflects ultraviolet light UV, a light reflection layer 20 that reflects visible light and infrared light, and infrared light IR. Emitting infrared radiation IR from the radiation surface 40;
And the radiation cooling device 100 is laminated | stacked in order of the ultraviolet reflective layer 10, the infrared radiation layer 30, and the light reflection layer 20 seeing from the radiation | emission surface 40 side.
In the present embodiment, the radiation surface 40 is the surface of the ultraviolet reflection layer 10 opposite to the surface in contact with the infrared radiation layer 30.
　つまり、本実施形態に係る放射冷却方法は、紫外光ＵＶを反射する紫外反射層１０と、可視光及び赤外光を反射する光反射層２０と、赤外光ＩＲを放射する赤外放射層３０とを、紫外反射層１０、赤外放射層３０、および光反射層２０の順に積層し、赤外光ＩＲを紫外反射層１０の赤外放射層３０と接する面とは反対側の放射面４０から放射する。 That is, the radiation cooling method according to the present embodiment includes the ultraviolet reflection layer 10 that reflects ultraviolet light UV, the light reflection layer 20 that reflects visible light and infrared light, and an infrared radiation layer that emits infrared light IR. 30 is stacked in the order of the ultraviolet reflection layer 10, the infrared radiation layer 30, and the light reflection layer 20, and the radiation surface on the opposite side to the surface of the ultraviolet reflection layer 10 in contact with the infrared radiation layer 30 Emit from 40
　紫外反射層１０は、紫外光ＵＶを反射し、可視光ＶＬおよび赤外光ＩＲを透過する光学構造を有する、誘電体で成る層である。本実施形態では、紫外反射層１０は、図２に示すように、二種以上の誘電体を積層して成る。図２に示す紫外反射層１０は、誘電体でなる層として、誘電体層１１から誘電体層１５を積層して備える。
　紫外反射層１０は、一方の面が、赤外放射層３０と密接している。 The ultraviolet reflection layer 10 is a layer made of a dielectric, which has an optical structure that reflects ultraviolet light UV and transmits visible light VL and infrared light IR. In the present embodiment, the ultraviolet reflection layer 10 is formed by laminating two or more types of dielectrics, as shown in FIG. The ultraviolet reflective layer 10 shown in FIG. 2 has a dielectric layer 11 and a dielectric layer 15 stacked on top of each other as a layer made of a dielectric.
One surface of the ultraviolet reflection layer 10 is in close contact with the infrared radiation layer 30.
　なお、本実施形態において紫外光ＵＶとは、その波長が１０ｎｍから４００ｎｍの電磁波のことを言う。また、本実施形態において赤外光ＩＲとは、その波長がおよそ７００ｎｍから２００００ｎｍの電磁波のことを言う。また、本実施形態において可視光ＶＬとは、その波長がおよそ４００ｎｍから７００ｎｍの電磁波のことを言う。 In the present embodiment, the ultraviolet light UV means an electromagnetic wave having a wavelength of 10 nm to 400 nm. Further, in the present embodiment, the infrared light IR refers to an electromagnetic wave having a wavelength of about 700 nm to 20000 nm. Further, in the present embodiment, the visible light VL refers to an electromagnetic wave having a wavelength of approximately 400 nm to 700 nm.
　紫外反射層１０の誘電体としては、二酸化ケイ素（ＳｉＯ２）、酸化アルミニウム（サファイア）、窒化ケイ素（ＳｉＮ）、二酸化ジルコニウム（ＺｎＯ）、二酸化チタン（ＴｉＯ２）、酸化マグネシウム（ＭｇＯ）、酸化ハフニウム（ＨｆＯ２）、窒化アルミニウム（ＡｌＮ）、酸化亜鉛（ＺｎＯ）、五酸化ニオブ（Ｎｂ２Ｏ５）のいずれかから選択される。 As a dielectric of the ultraviolet reflective layer 10, silicon dioxide (SiO 2 ), aluminum oxide (sapphire), silicon nitride (SiN), zirconium dioxide (ZnO), titanium dioxide (TiO 2 ), magnesium oxide (MgO), hafnium oxide It is selected from any of (HfO 2 ), aluminum nitride (AlN), zinc oxide (ZnO), and niobium pentoxide (Nb 2 O 5 ).
　紫外反射層１０の誘電体の層は、それぞれの層が２００ｎｍ未満の膜状でなる。この膜状の層は、例えば、いわゆるＣＶＤ法や、スパッタリング法で形成可能であり、その形成方法については問わない。 The dielectric layers of the ultraviolet reflective layer 10 are each in the form of a film of less than 200 nm. This film-like layer can be formed, for example, by the so-called CVD method or sputtering method, and there is no limitation on its formation method.
　紫外反射層１０の赤外放射層３０と接する面とは反対側の面、すなわち、雰囲気に開放されている側の面は、放射冷却装置１００において、赤外光ＩＲを放射する放射面４０としても機能する。つまり、紫外反射層１０の赤外放射層３０と接する面に対して反対側（他端側）にある誘電体の層における、当該層の雰囲気に開放されている側の面が、放射面４０である。言い換えると、紫外反射層１０の、雰囲気に開放されている側の誘電体の層の表面が、放射冷却装置１００の放射面４０となる。 The surface on the opposite side to the surface in contact with the infrared radiation layer 30 of the ultraviolet reflective layer 10, that is, the surface on the side open to the atmosphere is a radiation surface 40 that emits infrared light IR in the radiation cooling device 100. Also works. That is, the surface of the dielectric layer on the opposite side (the other end side) to the surface of the ultraviolet reflection layer 10 in contact with the infrared radiation layer 30 is the radiation surface of the layer that is open to the atmosphere. It is. In other words, the surface of the dielectric layer on the side of the ultraviolet reflection layer 10 that is open to the atmosphere is the radiation surface 40 of the radiation cooling device 100.
　放射面４０となる誘電体層１１は、二酸化ケイ素、酸化アルミニウム、窒化ケイ素、二酸化ジルコニウムのいずれかから選択される材料（物質）で成る。図２には、誘電体層１１が酸化アルミニウムとしてのサファイアで形成される場合を図示している。 The dielectric layer 11 to be the radiation surface 40 is made of a material (material) selected from any of silicon dioxide, aluminum oxide, silicon nitride and zirconium dioxide. FIG. 2 shows the case where the dielectric layer 11 is formed of sapphire as aluminum oxide.
　図２の誘電体層１１から誘電体層１５はそれぞれ順に、サファイア、二酸化ケイ素、サファイア、二酸化ケイ素、サファイアで成る場合を図示している。
　また、図２には、誘電体の厚み（層厚）が２００ｎｍ未満である具体例として、誘電体層１１から誘電体層１５の厚みがそれぞれ順に、３０ｎｍ、５０ｎｍ、５０ｎｍ、４０ｎｍ、４０ｎｍである場合を例示して図示している。
　尚、図７及び図８に、図２で示す紫外反射層１０の反射率、透過率、吸収率を示す。紫外反射層１０は、大気の窓に相当する１００００ｎｍ付近の波長域において吸収率が高く、１００００ｎｍ付近の波長域の赤外光を放射することになる。 The dielectric layer 11 to the dielectric layer 15 in FIG. 2 are illustrated in the case of sapphire, silicon dioxide, sapphire, silicon dioxide and sapphire in this order.
Further, in FIG. 2, as a specific example in which the thickness (layer thickness) of the dielectric is less than 200 nm, the thicknesses of the dielectric layer 11 to the dielectric layer 15 are 30 nm, 50 nm, 50 nm, 40 nm, and 40 nm in this order. The case is illustrated.
7 and 8 show the reflectance, the transmittance, and the absorptivity of the ultraviolet reflection layer 10 shown in FIG. The ultraviolet reflection layer 10 has a high absorptivity in a wavelength range around 10000 nm corresponding to the window of the atmosphere, and emits infrared light in a wavelength range around 10000 nm.
　赤外放射層３０は、光Ｌを透過し、また赤外光ＩＲを放射する層である。
　赤外放射層３０は、一方の面が紫外反射層１０と密接し、他方の面が光反射層２０と密接している。
　なお、本実施形態において「光を透過する」などの記載する場合は、その光の一部を吸収および反射し、大部分を透過する場合を含む。たとえば、入射した光のエネルギーの９０％以上を透過する場合は、単に「光を透過する」などと記載する。 The infrared radiation layer 30 is a layer that transmits the light L and emits infrared light IR.
One surface of the infrared radiation layer 30 is in close contact with the ultraviolet reflection layer 10, and the other surface is in close contact with the light reflection layer 20.
In the case where “transmits light” or the like is described in the present embodiment, the case where part of the light is absorbed and reflected and most of the light is transmitted is included. For example, when 90% or more of the energy of incident light is transmitted, it is simply described as "transmits light".
　赤外放射層３０は、紫外反射層１０および光反射層２０と熱伝導可能に接続されている。つまり、赤外放射層３０は、自身の有する熱エネルギーと、紫外反射層１０からの入熱（熱エネルギー）と、光反射層２０からの入熱（熱エネルギー）とを、赤外光ＩＲに変換して放射する。 The infrared radiation layer 30 is connected to the ultraviolet reflection layer 10 and the light reflection layer 20 so as to be thermally conductive. That is, the infrared radiation layer 30 converts the heat energy of its own, the heat input from the ultraviolet reflection layer 10 (heat energy), and the heat input from the light reflection layer 20 (thermal energy) into infrared light IR. Convert and radiate.
　赤外放射層３０は、本実施形態では、光Ｌを透過し、大気の窓の領域である波長８０００ｎｍから２００００ｎｍの間における、波長１００００ｎｍ付近の赤外光ＩＲを効率よく放射する、二酸化ケイ素で成る。 In the present embodiment, the infrared radiation layer 30 is made of silicon dioxide which transmits the light L and efficiently radiates infrared light IR around a wavelength of 10000 nm in the window region of the atmosphere between wavelengths 8000 nm and 20000 nm. Become.
　赤外放射層３０は、その厚みが１μｍを超えるように形成される。通常は、赤外放射層３０は、その厚みが１μｍを超えていればよく、１００００μｍ以下程度とするのが経済的であり、特に２０μｍ以上１００００μｍ以下の範囲とすると、経済面と性能面のバランスが良い。 The infrared radiation layer 30 is formed to have a thickness of more than 1 μm. Usually, the thickness of the infrared radiation layer 30 may be more than 1 μm, and it is economical to set it to about 10000 μm or less, and in particular, it is a balance of economic and performance if it is in the range of 20 μm to 10000 μm. Is good.
　図３に、二酸化ケイ素で成る赤外放射層３０の層厚（厚み）を、１μｍ、２０μｍ、１００μｍとした場合の、赤外放射層３０の放射スペクトルを示す。縦軸は、赤外放射層３０の光の吸収率ＡＢを示し、横軸が波長ＷＬを示す。なお、１μｍの二酸化ケイ素の赤外放射層３０はスパッタリングにより作製された膜状の層であり、２０μｍ、１００μｍの二酸化ケイ素の赤外放射層３０は溶融固化して形成した層である。 FIG. 3 shows the radiation spectrum of the infrared radiation layer 30 when the layer thickness (thickness) of the infrared radiation layer 30 made of silicon dioxide is 1 μm, 20 μm, and 100 μm. The vertical axis indicates the light absorptivity AB of the infrared radiation layer 30, and the horizontal axis indicates the wavelength WL. The 1 μm infrared radiation layer 30 of silicon dioxide is a film-like layer prepared by sputtering, and the 20 μm and 100 μm infrared radiation layer 30 of silicon dioxide is a layer formed by melting and solidification.
　なお、キルヒホッフの法則により、任意の波長における光の吸収率と光の放射率は等しいため、図３において赤外放射層３０の吸収率ＡＢが示す分布は、赤外放射層３０が放射する場合の放射光の強度の分布に等しい。 Note that according to Kirchhoff's law, the absorptivity of light at an arbitrary wavelength is equal to the emissivity of light, so the distribution shown by the absorptivity AB of the infrared emitting layer 30 in FIG. Equal to the distribution of the intensity of the emitted light.
　光反射層２０は、光Ｌを反射する金属で成る層であり、いわゆる鏡として機能する層である。
　本実施形態では、光反射層２０は、金属としての銀またはアルミニウムのいずれかで形成する。本実施形態では、光反射層２０は、銀である場合を説明している。 The light reflection layer 20 is a layer made of a metal that reflects the light L, and is a layer that functions as a so-called mirror.
In the present embodiment, the light reflection layer 20 is formed of either silver or aluminum as a metal. In the present embodiment, the case where the light reflection layer 20 is silver is described.
　光反射層２０は、その層厚が８０ｎｍよりも厚く形成して用いる。
　光反射層２０が、８０ｎｍ以下の膜厚となると、波長２０００ｎｍ以下の波長域において透過が生じはじめ、光の反射性能が発揮されなくなるためである。
　なお、光反射層２０の厚みが、８０ｎｍを超えると、光の透過は生じず、光の反射率は変化しない。すなわち、光反射層２０の厚みに係る技術的な上限は存在しない。しかし、経済面では、光反射層２０の厚みは、１ｍｍ以下で足りる。
　なお、図１には、光反射層２０が８０ｎｍを超える厚みである場合の具体例として、光反射層２０が、厚み２００ｎｍの銀である場合を示している。 The light reflecting layer 20 is formed to be thicker than 80 nm.
When the light reflection layer 20 has a film thickness of 80 nm or less, transmission starts to occur in a wavelength range of wavelength 2000 nm or less, and light reflection performance can not be exhibited.
When the thickness of the light reflecting layer 20 exceeds 80 nm, transmission of light does not occur, and the reflectance of light does not change. That is, there is no technical upper limit regarding the thickness of the light reflection layer 20. However, in terms of economy, the thickness of the light reflecting layer 20 may be 1 mm or less.
In addition, in FIG. 1, the case where the light reflection layer 20 is silver with a thickness of 200 nm is shown as a specific example in the case where the light reflection layer 20 has a thickness exceeding 80 nm.
〔実施例の説明〕
　以下では、本実施形態における実施例を説明する。
　以下で説明する実施例１、実施例２および実施例３はそれぞれ、図１に示す構造を備えた、本実施形態に係る放射冷却装置１００の一つの態様である。この放射冷却装置１００は、上述のとおり、放射面４０の側から見て、紫外反射層１０、赤外放射層３０、および光反射層２０の順に積層されている。 Description of the embodiment
Below, the Example in this embodiment is demonstrated.
The first embodiment, the second embodiment, and the third embodiment described below are respectively one aspect of the radiation cooling device 100 according to the present embodiment, having the structure shown in FIG. 1. As described above, the radiation cooling device 100 is laminated in the order of the ultraviolet reflection layer 10, the infrared radiation layer 30, and the light reflection layer 20 as viewed from the side of the radiation surface 40.
　以下で説明する比較例１および比較例２はそれぞれ、図４に示す構造を備えた、従来の放射冷却装置２００である。この放射冷却装置２００は、放射面４０の側から見て、赤外放射層３０、紫外反射層１０、および光反射層２０の順に積層されている。 Comparative Example 1 and Comparative Example 2 described below are each a conventional radiation cooling device 200 having the structure shown in FIG. 4. The radiation cooling device 200 is stacked in the order of the infrared radiation layer 30, the ultraviolet reflection layer 10, and the light reflection layer 20, as viewed from the radiation surface 40 side.
　以下では、実施例１、実施例２および実施例３の放射冷却装置１００と、比較例１および比較例２の従来の放射冷却装置２００との、雰囲気温度が３０℃の場合の冷却性能を比較する。
　実施例１、実施例２、実施例３、比較例１および比較例２のいずれの場合も、放射冷却装置１００または放射冷却装置２００の放射面４０を天上（空、宇宙）に向けて、放射面４０を鉛直方向上向きに設置する。
　実施例１、実施例２、実施例３、比較例１および比較例２のいずれの場合も、光として太陽光が、材料の鉛直方向からおよそ１０００Ｗ／ｍ２のエネルギーで入射する環境下に置く。太陽光は、主として放射面４０から、放射冷却装置１００または放射冷却装置２００に対して入射する。 In the following, the cooling performances at an ambient temperature of 30 ° C. of the radiation cooling devices 100 of Example 1, Example 2 and Example 3 and the conventional radiation cooling device 200 of Comparative Example 1 and Comparative Example 2 are compared. Do.
In any of the first embodiment, the second embodiment, the third embodiment, the first comparison example and the second comparison example, the radiation surface 40 of the radiation cooling device 100 or the radiation cooling device 200 is directed to the sky (empty, space) The plane 40 is placed vertically upward.
In any of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2, sunlight is used as light in an environment where it is incident at an energy of approximately 1000 W / m 2 from the vertical direction of the material. . Sunlight is incident on the radiation cooling device 100 or the radiation cooling device 200 mainly from the radiation surface 40.
　実施例１、実施例２、実施例３、比較例１および比較例２における、冷却性能の比較を表１から表５に示す。
　表１には、実施例１の場合の冷却性能を示す。
　表２には、実施例２の場合の冷却性能を示す。
　表３には、実施例３の場合の冷却性能を示す。
　表４には、比較例１の場合の冷却性能を示す。
　表５には、比較例２の場合の冷却性能を示す。
　なお、表１から表５に示す項目はそれぞれ同じである。 The comparison of the cooling performance in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 is shown in Tables 1 to 5.
Table 1 shows the cooling performance in the case of Example 1.
Table 2 shows the cooling performance in the case of Example 2.
Table 3 shows the cooling performance in the case of Example 3.
Table 4 shows the cooling performance in the case of Comparative Example 1.
Table 5 shows the cooling performance in the case of Comparative Example 2.
The items shown in Tables 1 to 5 are the same.
　実施例１、実施例２および実施例３の放射冷却装置１００と、比較例１および比較例２の従来の放射冷却装置２００とに共通する構成を説明する。
　光反射層２０は以下の構成で比較する。
　実施例１、実施例２、実施例３、比較例１および比較例２の光反射層２０はいずれも、厚み２００ｎｍの銀の層で成る。
　以下では光反射層２０についての説明を省略する。 The configuration common to the radiation cooling devices 100 of the first embodiment, the second embodiment and the third embodiment and the conventional radiation cooling devices 200 of the first comparison example and the second comparison example will be described.
The light reflecting layer 20 is compared in the following configuration.
The light reflecting layers 20 of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 are all made of a silver layer having a thickness of 200 nm.
The description of the light reflection layer 20 is omitted below.
　赤外放射層３０は以下の構成で比較する。
　実施例１、実施例２、実施例３、比較例１および比較例２の赤外放射層３０を形成する材料（物質）はいずれも、二酸化ケイ素である。
　実施例１、実施例２、実施例３、比較例１および比較例２のそれぞれの場合において、赤外放射層３０の厚みが、１μｍ、１０μｍ、２０μｍ、１００μｍ、１０００μｍ、１００００μｍ、１０００００μｍである場合を比較する。なお、１μｍ、１０μｍの二酸化ケイ素の赤外放射層３０はスパッタリングにより作製された膜状の層である。２０μｍ、１００μｍ、１０００μｍ、１００００μｍ、１０００００μｍの二酸化ケイ素の赤外放射層３０は溶融固化して形成した層である。
　以下では赤外放射層３０についての説明を省略する。
　以下、実施例１、実施例２、実施例３、比較例１および比較例２の異なる構成部分を説明する。 The infrared radiation layer 30 is compared in the following configuration.
The materials (substances) forming the infrared radiation layer 30 of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 are all silicon dioxide.
When the thickness of the infrared radiation layer 30 is 1 μm, 10 μm, 20 μm, 100 μm, 1000 μm, 10000 μm, 100000 μm in each of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 Compare The infrared radiation layer 30 of silicon dioxide of 1 μm and 10 μm is a film-like layer produced by sputtering. The infrared radiation layer 30 of silicon dioxide of 20 μm, 100 μm, 1000 μm, 10000 μm and 100000 μm is a layer formed by melting and solidification.
The description of the infrared radiation layer 30 is omitted below.
Hereinafter, different component parts of Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2 will be described.
　〔実施例１〕
　実施例１の放射冷却装置１００は、以下の構成で成る。
　紫外反射層１０は、図２に示すように、誘電体でなる層として、誘電体層１１から誘電体層１５を積層して備える。
　誘電体層１１から誘電体層１５はそれぞれ順に、サファイア、二酸化ケイ素、サファイア、二酸化ケイ素、サファイアで成る。
　また、誘電体層１１から誘電体層１５の厚みはそれぞれ順に、３０ｎｍ、５０ｎｍ、５０ｎｍ、４０ｎｍ、４０ｎｍである。 Example 1
The radiation cooling device 100 according to the first embodiment has the following configuration.
As shown in FIG. 2, the ultraviolet reflection layer 10 is formed by laminating the dielectric layer 11 to the dielectric layer 15 as a layer made of a dielectric.
The dielectric layer 11 to the dielectric layer 15 are respectively made of sapphire, silicon dioxide, sapphire, silicon dioxide and sapphire.
In addition, the thicknesses of the dielectric layer 11 to the dielectric layer 15 are 30 nm, 50 nm, 50 nm, 40 nm, and 40 nm, respectively.
　〔実施例２〕
　実施例２の放射冷却装置１００は、以下の構成で成る。
　実施例２は、実施例１と、紫外反射層１０の積層構造が異なる。
　紫外反射層１０は、図５に示すように、誘電体でなる層として、誘電体層５１から誘電体層６６を備える。
　誘電体層５１から誘電体層６６はそれぞれ順に、二酸化ケイ素、二酸化チタンを交互に１６層積層したものである。
　また、誘電体層５１から誘電体層６６の厚みはそれぞれ順に、１００ｎｍ、３３ｎｍ、６５ｎｍ、１３ｎｍ、８０ｎｍ、３７ｎｍ、２３ｎｍ、４６ｎｍ、１８０ｎｍ、１０６ｎｍ、１７２ｎｍ、８８ｎｍ、１７２ｎｍ、１０４ｎｍ、１７５ｎｍ、１０３ｎｍである。 Example 2
The radiation cooling device 100 of the second embodiment has the following configuration.
The second embodiment is different from the first embodiment in the laminated structure of the ultraviolet reflective layer 10.
The ultraviolet reflective layer 10 is provided with dielectric layers 51 to 66 as dielectric layers as shown in FIG.
The dielectric layer 51 to the dielectric layer 66 are formed by alternately stacking 16 layers of silicon dioxide and titanium dioxide, respectively.
In addition, the thicknesses of the dielectric layer 51 to the dielectric layer 66 are 100 nm, 33 nm, 65 nm, 13 nm, 80 nm, 37 nm, 23 nm, 46 nm, 106 nm, 106 nm, 172 nm, 172 nm, 104 nm, 175 nm, and 103 nm respectively. .
　〔実施例３〕
　実施例３は、実施例１や実施例２と、紫外反射層１０の積層構造が異なる。
　紫外反射層１０は、図６に示すように、誘電体でなる層として、誘電体層７１から誘電体層７４を備える。
　誘電体層７１から誘電体層７４はそれぞれ順に、二酸化ケイ素、五酸化ニオブを交互に４層積層したものである。
　また、誘電体層７１から誘電体層７４の厚みはそれぞれ順に、１１１ｎｍ、２５ｎｍ、５６ｎｍ、２９ｎｍである。 [Example 3]
The third embodiment is different from the first and second embodiments in the laminated structure of the ultraviolet reflective layer 10.
As shown in FIG. 6, the ultraviolet reflective layer 10 includes dielectric layers 71 to 74 as dielectric layers.
The dielectric layer 71 to the dielectric layer 74 are formed by alternately stacking four layers of silicon dioxide and niobium pentoxide in order.
The thicknesses of the dielectric layer 71 to the dielectric layer 74 are 111 nm, 25 nm, 56 nm, and 29 nm, respectively.
　尚、図９及び図１０に、図６で示す紫外反射層１０の反射率、透過率、吸収率を示す。紫外反射層１０は、大気の窓に相当する１００００ｎｍ付近の波長域において吸収率が高く、１００００ｎｍ付近の波長域の赤外光を放射することになる。 9 and 10 show the reflectance, the transmittance, and the absorptivity of the ultraviolet reflection layer 10 shown in FIG. The ultraviolet reflection layer 10 has a high absorptivity in a wavelength range around 10000 nm corresponding to the window of the atmosphere, and emits infrared light in a wavelength range around 10000 nm.
〔比較例１〕
　比較例１の放射冷却装置２００は、実施例１の場合と同じ積層構造の紫外反射層１０を備える。
　比較例１の放射冷却装置２００は、実施例１の場合と、紫外反射層１０が配置される位置が異なる。 Comparative Example 1
The radiation cooling device 200 of Comparative Example 1 includes the ultraviolet reflective layer 10 having the same laminated structure as that of Example 1.
The radiation cooling device 200 of Comparative Example 1 differs from the case of Example 1 in the position where the ultraviolet reflective layer 10 is disposed.
〔比較例２〕
　比較例２の放射冷却装置２００は、実施例２の場合と同じ積層構造の紫外反射層１０を備える。
　比較例２の放射冷却装置２００は、実施例２の場合と、紫外反射層１０が配置される位置が異なる。 Comparative Example 2
The radiation cooling device 200 of Comparative Example 2 includes the ultraviolet reflective layer 10 having the same laminated structure as that of Example 2.
The radiation cooling device 200 of Comparative Example 2 differs from the case of Example 2 in the position where the ultraviolet reflective layer 10 is disposed.
　表１から表５の以下のＰ１からＰ４は、放射冷却装置１００または放射冷却装置２００における以下の特性を示す。
　ｔ　：赤外放射層３０の厚み(μｍ)
　Ｐ１：放射のエネルギーの密度(Ｗ／ｍ２)
　Ｐ２：太陽光からの入熱のエネルギーの密度(Ｗ／ｍ２)
　Ｐ３：雰囲気（大気）からの入熱のエネルギーの密度(Ｗ／ｍ２)
　Ｐ４：冷却能力のエネルギーの密度(Ｗ／ｍ２)
　Ｔ　：放射冷却装置１００または放射冷却装置２００の平衡温度（℃）
　なお、上述の「密度」は、放射面４０の表面の面積に対するエネルギーの出入りの密度を意味する。
　また、Ｐ２は、およそ１０００Ｗ／ｍ２のエネルギーで入射された太陽光のエネルギーのうち、放射冷却装置１００または放射冷却装置２００で反射されなかったエネルギーを意味する。
　また、Ｐ４の値は、Ｐ１の値から、Ｐ２の値とＰ３の値との合計を差し引いた値である。
　Ｐ１及びＰ３の値は、放射面４０に対する放射角が６０度であるとして計算した値である。 The following P1 to P4 in Tables 1 to 5 show the following characteristics of the radiation cooling device 100 or the radiation cooling device 200.
t: thickness of infrared radiation layer 30 (μm)
P1: Density of energy of radiation (W / m 2 )
P2: Density of energy input from sunlight (W / m 2 )
P3: Energy density of heat input from atmosphere (atmosphere) (W / m 2 )
P4: Energy density of cooling capacity (W / m 2 )
T: Equilibrium temperature (° C.) of radiation cooling device 100 or radiation cooling device 200
In addition, the above-mentioned "density" means the density of the in and out of the energy with respect to the area of the surface of radiation surface 40.
Moreover, P2 means the energy which was not reflected by radiation cooling device 100 or radiation cooling device 200 among the energy of the sunlight which injected with energy of about 1000 W / m 2 .
Also, the value of P4 is a value obtained by subtracting the sum of the values of P2 and P3 from the value of P1.
The values of P1 and P3 are calculated assuming that the radiation angle with respect to the radiation surface 40 is 60 degrees.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　表１から表５によれば、実施例１、実施例２および実施例３の放射冷却装置１００は、比較例１および比較例２の放射冷却装置２００に比べて、冷却能力が高いことがわかる。
　したがって、放射冷却装置２００のように、放射面４０の側から見て、赤外放射層３０、紫外反射層１０、および光反射層２０の順に積層するよりも、放射冷却装置１００のように、放射面４０の側から見て、紫外反射層１０、赤外放射層３０、および光反射層２０の順に積層する方が、冷却能力が高いと判断できる。
　つまり、本実施形態にかかる放射冷却装置１００と、従来の放射冷却装置２００との冷却能力の差は、本実施形態にかかる放射冷却装置１００の場合には、紫外光の吸収が抑制されたためであると考えられる。 According to Tables 1 to 5, it can be seen that the radiation cooling devices 100 of Example 1, Example 2 and Example 3 have a higher cooling capacity than the radiation cooling devices 200 of Comparative Example 1 and Comparative Example 2. .
Therefore, rather than laminating the infrared radiation layer 30, the ultraviolet reflection layer 10, and the light reflection layer 20 in order from the side of the radiation surface 40 as in the radiation cooling device 200, as in the radiation cooling device 100, It can be judged that the cooling ability is higher when the ultraviolet reflective layer 10, the infrared radiation layer 30, and the light reflective layer 20 are laminated in order as viewed from the radiation surface 40 side.
That is, the difference in cooling capacity between the radiation cooling device 100 according to the present embodiment and the conventional radiation cooling device 200 is that absorption of ultraviolet light is suppressed in the case of the radiation cooling device 100 according to the present embodiment. It is believed that there is.
　実施例１の表１と、実施例２の表２と、実施例３の表３との比較によれば、紫外反射層１０の誘電体でなる層が適切に積層されれば、積層の層数によらず、良好な冷却能力を発揮すると言える。しかも、紫外反射層１０を形成する材料（物質）が同じであれば、積層の層数が増加すると、冷却能力が向上する傾向にあることがわかる。 According to the comparison of Table 1 of Example 1, Table 2 of Example 2, and Table 3 of Example 3, if the layer made of the dielectric of the ultraviolet reflective layer 10 is properly laminated, the layers of the lamination Regardless of the number, it can be said that it exhibits good cooling capacity. Moreover, it can be seen that if the material (substance) forming the ultraviolet reflective layer 10 is the same, the cooling capacity tends to improve as the number of layers in the laminate increases.
　実施例１の表１と、実施例２の表２と、実施例３の表３とによれば、赤外放射層３０の厚みは、１μｍ以上、好ましくは１μｍを超えると、十分な冷却性能を発揮することがわかる。特に、赤外放射層３０の厚みが、１０μｍ以上であると、特に良好な冷却性能を発揮することがわかる。 According to Table 1 of Example 1, Table 2 of Example 2, and Table 3 of Example 3, when the thickness of the infrared radiation layer 30 is 1 μm or more, preferably more than 1 μm, sufficient cooling performance is obtained. It can be seen that In particular, it can be seen that particularly good cooling performance is exhibited when the thickness of the infrared radiation layer 30 is 10 μm or more.
　また、赤外放射層３０の厚みは、１０００００μｍに達する場合でも良好な冷却性能を発揮し、赤外放射層３０の厚みは１０００００μｍを超える場合においても良好な冷却性能を発揮するものと想定される。ただし、通常は、赤外放射層３０の厚みは１０００００μｍあれば十分に足りる。 Further, it is assumed that the thickness of the infrared radiation layer 30 exhibits good cooling performance even when reaching 100,000 μm, and the thickness of the infrared radiation layer 30 exhibits good cooling performance even when it exceeds 100,000 μm. . However, in general, the thickness of the infrared radiation layer 30 is sufficient if 100,000 μm.
　以上のようにして、紫外光の吸収を抑制した放射冷却装置および放射冷却方法を提供することができる。 As described above, it is possible to provide a radiation cooling device and a radiation cooling method in which absorption of ultraviolet light is suppressed.
［別実施形態］
（１）上記実施形態では、紫外反射層１０の誘電体でなる層が５層の場合、または１６層の場合を例示したが、紫外反射層１０の誘電体でなる層はこれらの積層の層数に限られない。
　紫外反射層１０の誘電体でなる層は、異なる誘電体が１層以上、好ましくは２層以上であればよい。また、紫外反射層１０の誘電体でなる層の層数は偶数でも奇数でもよい。 [Another embodiment]
(1) Although the case where the layer which consists of a dielectric of the ultraviolet reflective layer 10 is five layers or the case of 16 layers was illustrated in the said embodiment, the layer which consists of a dielectric of the ultraviolet reflective layer 10 is a layer of these laminations It is not limited to the number.
The layer made of the dielectric of the ultraviolet reflective layer 10 may have one or more, preferably two or more different dielectrics. Further, the number of layers of the dielectric of the ultraviolet reflective layer 10 may be even or odd.
（２）上記実施形態では、光反射層２０が銀である場合を説明したが、光反射層２０がアルミニウムや、金である場合にも同様の効果を奏することができる。 (2) Although the case where the light reflection layer 20 is silver has been described in the above embodiment, the same effect can be obtained when the light reflection layer 20 is aluminum or gold.
（３）上記実施形態では、紫外反射層１０における放射面４０を有する誘電体でなる層が、二酸化ケイ素または酸化アルミニウムである場合を例示した。
　しかし、放射面４０を有する誘電体でなる層が、窒化ケイ素や二酸化ジルコニウム、または二酸化チタンである場合もある。 (3) In the said embodiment, the case where the layer which consists of a dielectric which has the radiation | emission surface 40 in the ultraviolet reflective layer 10 was silicon dioxide or aluminum oxide was illustrated.
However, the dielectric layer having the emitting surface 40 may be silicon nitride, zirconium dioxide or titanium dioxide.
（４）上記実施形態では、紫外反射層１０における誘電体でなる層が、二酸化ケイ素、酸化アルミニウムまたは二酸化チタンである場合を例示した。
　しかし、紫外反射層１０における誘電体でなる層を形成する材料（物質）が、窒化ケイ素、二酸化ジルコニウム、二酸化チタン、酸化マグネシウム、酸化ハフニウム、窒化アルミニウム、酸化亜鉛、五酸化ニオブである場合もある。また、紫外反射層１０における誘電体でなるそれぞれの層を形成する材料（物質）の組み合わせも、上記実施形態における記載の範囲に限られない。 (4) In the said embodiment, the case where the layer which consists of a dielectric in the ultraviolet reflective layer 10 is silicon dioxide, aluminum oxide, or titanium dioxide was illustrated.
However, the material (substance) for forming the dielectric layer in the ultraviolet reflective layer 10 may be silicon nitride, zirconium dioxide, titanium dioxide, magnesium oxide, hafnium oxide, aluminum nitride, zinc oxide, niobium pentoxide . Moreover, the combination of the material (substance) which forms each layer which consists of a dielectric in the ultraviolet reflective layer 10 is not restricted to the range as described in the said embodiment.
（５）上記実施形態では、赤外線放射層３０を形成する材料が、二酸化ケイ素である場合を例示したが、赤外線放射層３０を形成する材料としては、ホウケイ酸ガラスであるテンパックス（登録商標、以下同じ）等の他の材料を用いても良い。
　尚、図１１に、テンパックスに関する波長と吸収率との関係、つまり、テンパックスの吸収率（太実線）、テンパックスと光反射層２０としての銀とを積層した場合の吸収率（一点鎖線）、実施例１の紫外線反射層とテンパックスと光反射層２０としての銀とを本発明の形態で積層した場合の吸収率（細実線）、実施例１の紫外線反射層とテンパックスとを積層した場合の吸収率（二点鎖線）、及び、テンパックスと実施例１の紫外線反射層と光反射層２０としての銀とを従来の形態で積層した場合の吸収率（細破線）、並びに、銀の吸収率（太破線）の夫々を示す。 (5) Although the case where the material which forms the infrared rays radiation layer 30 is silicon dioxide was illustrated in the above-mentioned embodiment, as a material which forms the infrared rays radiation layer 30, Tenpax (registered trademark), which is borosilicate glass, Other materials such as the following may be used.
In FIG. 11, the relationship between the wavelength and the absorptivity with respect to Tempax, that is, the absorptivity of Tempax (thick solid line), the absorptivity in the case where Tempax and silver as light reflecting layer 20 are laminated (dotted-dotted line Absorptivity (thin solid line) in the case where the ultraviolet ray reflection layer of Example 1, the Tempax and the silver as the light reflection layer 20 are laminated in the form of the present invention, and the ultraviolet ray reflection layer of Example 1 and Tempax The absorptivity when laminated (two-dot chain line), and the absorptivity (thin broken line) when Tempacx, the ultraviolet reflection layer of Example 1 and silver as the light reflection layer 20 are laminated in a conventional form, and , The absorption rate of silver (thick broken line) respectively.
　なお、上記実施形態（別実施形態を含む、以下同じ）で開示される構成は、矛盾が生じない限り、他の実施形態で開示される構成と組み合わせて適用することが可能であり、また、本明細書において開示された実施形態は例示であって、本発明の実施形態はこれに限定されず、本発明の目的を逸脱しない範囲内で適宜改変することが可能である。 Note that the configurations disclosed in the above-described embodiment (including the other embodiments, and the same hereinafter) can be applied in combination with the configurations disclosed in the other embodiments as long as no contradiction arises. The embodiment disclosed in the present specification is an exemplification, and the embodiment of the present invention is not limited thereto, and can be appropriately modified without departing from the object of the present invention.
　本発明は、紫外光の吸収を抑制した放射冷却装置および放射冷却方法に適用できる。 The present invention is applicable to a radiation cooling device and a radiation cooling method in which absorption of ultraviolet light is suppressed.
１０　　　：紫外反射層
１１　　　：誘電体層（誘電体、紫外反射層）
１２　　　：誘電体層（誘電体、紫外反射層）
１３　　　：誘電体層（誘電体、紫外反射層）
１４　　　：誘電体層（誘電体、紫外反射層）
１５　　　：誘電体層（誘電体、紫外反射層）
２０　　　：光反射層（誘電体、紫外反射層）
３０　　　：赤外放射層
４０　　　：放射面
５１　　　：誘電体層（誘電体、紫外反射層）
５２　　　：誘電体層（誘電体、紫外反射層）
５３　　　：誘電体層（誘電体、紫外反射層）
５４　　　：誘電体層（誘電体、紫外反射層）
５５　　　：誘電体層（誘電体、紫外反射層）
５６　　　：誘電体層（誘電体、紫外反射層）
５７　　　：誘電体層（誘電体、紫外反射層）
５８　　　：誘電体層（誘電体、紫外反射層）
５９　　　：誘電体層（誘電体、紫外反射層）
６０　　　：誘電体層（誘電体、紫外反射層）
６１　　　：誘電体層（誘電体、紫外反射層）
６２　　　：誘電体層（誘電体、紫外反射層）
６３　　　：誘電体層（誘電体、紫外反射層）
６４　　　：誘電体層（誘電体、紫外反射層）
６５　　　：誘電体層（誘電体、紫外反射層）
６６　　　：誘電体層（誘電体、紫外反射層）
７１　　　：誘電体層（誘電体、紫外反射層）
７２　　　：誘電体層（誘電体、紫外反射層）
７３　　　：誘電体層（誘電体、紫外反射層）
７４　　　：誘電体層（誘電体、紫外反射層）
１００　　：放射冷却装置
２００　　：放射冷却装置
２００ｎｍ：厚み
ＩＲ　　　：赤外光
Ｌ　　　　：光
ＵＶ　　　：紫外光
ＶＬ　　　：可視光 10: UV reflective layer 11: dielectric layer (dielectric, UV reflective layer)
12: Dielectric layer (dielectric, ultraviolet reflection layer)
13: Dielectric layer (dielectric, ultraviolet reflection layer)
14: Dielectric layer (dielectric, ultraviolet reflection layer)
15: Dielectric layer (dielectric, ultraviolet reflection layer)
20: Light reflecting layer (dielectric, ultraviolet reflecting layer)
30: infrared radiation layer 40: radiation surface 51: dielectric layer (dielectric, ultraviolet reflection layer)
52: Dielectric layer (dielectric, ultraviolet reflection layer)
53: Dielectric layer (dielectric, ultraviolet reflection layer)
54: Dielectric layer (dielectric, ultraviolet reflection layer)
55: Dielectric layer (dielectric, ultraviolet reflective layer)
56: Dielectric layer (dielectric, ultraviolet reflective layer)
57: Dielectric layer (dielectric, ultraviolet reflective layer)
58: Dielectric layer (dielectric, ultraviolet reflection layer)
59: Dielectric layer (dielectric, ultraviolet reflection layer)
60: Dielectric layer (dielectric, ultraviolet reflection layer)
61: Dielectric layer (dielectric, ultraviolet reflection layer)
62: Dielectric layer (dielectric, ultraviolet reflection layer)
63: Dielectric layer (dielectric, ultraviolet reflection layer)
64: Dielectric layer (dielectric, ultraviolet reflection layer)
65: Dielectric layer (dielectric, ultraviolet reflection layer)
66: Dielectric layer (dielectric, ultraviolet reflection layer)
71: Dielectric layer (dielectric, ultraviolet reflection layer)
72: Dielectric layer (dielectric, ultraviolet reflective layer)
73: Dielectric layer (dielectric, ultraviolet reflective layer)
74: Dielectric layer (dielectric, ultraviolet reflective layer)
100: radiation cooling device 200: radiation cooling device 200 nm: thickness IR: infrared light L: light UV: ultraviolet light VL: visible light

Claims (10)

  1. 　紫外光を反射する紫外反射層と、可視光及び赤外光を反射する光反射層と、赤外光を放射する赤外放射層とを備え、放射面から赤外光を放射する放射冷却装置において、
    　前記放射面の側から見て、前記紫外反射層、前記赤外放射層、および前記光反射層の順に積層して成る放射冷却装置。     A radiation cooling apparatus including an ultraviolet reflection layer that reflects ultraviolet light, a light reflection layer that reflects visible light and infrared light, and an infrared radiation layer that emits infrared light, and emitting infrared light from the radiation surface In
    The radiation cooling device which laminates | stacks in order of the said ultraviolet reflective layer, the said infrared radiation layer, and the said light reflection layer seeing from the side of the said radiation | emission surface.
  2. 　前記紫外反射層は、二種以上の誘電体を積層して成り、
    　前記誘電体は、二酸化ケイ素、酸化アルミニウム、窒化ケイ素、二酸化ジルコニウム、二酸化チタン、酸化マグネシウム、酸化ハフニウム、窒化アルミニウム、酸化亜鉛、五酸化ニオブのいずれかから選択される請求項１に記載の放射冷却装置。     The ultraviolet reflection layer is formed by laminating two or more dielectrics,
    The radiative cooling according to claim 1, wherein the dielectric is selected from any of silicon dioxide, aluminum oxide, silicon nitride, zirconium dioxide, titanium dioxide, magnesium oxide, hafnium oxide, aluminum nitride, zinc oxide and niobium pentoxide. apparatus.
  3. 　前記誘電体の層厚が、２００ｎｍ未満である請求項２に記載の放射冷却装置。 The radiation cooling device according to claim 2, wherein the layer thickness of the dielectric is less than 200 nm.
  4. 　前記放射面となる前記紫外反射層の前記誘電体は、二酸化ケイ素、酸化アルミニウム、窒化ケイ素、二酸化ジルコニウム、二酸化チタン、五酸化ニオブのいずれかから選択される請求項２または３に記載の放射冷却装置。 The radiation cooling according to claim 2 or 3, wherein the dielectric of the ultraviolet reflection layer to be the radiation surface is selected from any of silicon dioxide, aluminum oxide, silicon nitride, zirconium dioxide, titanium dioxide and niobium pentoxide. apparatus.
  5. 　前記赤外放射層は、二酸化ケイ素で成る請求項１から４の何れか一項に記載の放射冷却装置。 5. A radiation cooling device according to any one of the preceding claims, wherein the infrared radiation layer comprises silicon dioxide.
  6. 　前記赤外放射層の厚みが１μｍを超える厚みである請求項５に記載の放射冷却装置。 The radiation cooling device according to claim 5, wherein the thickness of the infrared radiation layer is greater than 1 μm.
  7. 　前記光反射層が、銀またはアルミニウムで成る請求項１から６の何れか一項に記載の放射冷却装置。 The radiation cooling device according to any one of claims 1 to 6, wherein the light reflection layer is made of silver or aluminum.
  8. 　前記光反射層の厚みが８０ｎｍを超える厚みである請求項７に記載の放射冷却装置。 The radiation cooling device according to claim 7, wherein the thickness of the light reflecting layer is greater than 80 nm.
  9. 　紫外光を反射する紫外反射層と、可視光及び赤外光を反射する光反射層と、赤外光を放射する赤外放射層とを、前記紫外反射層、前記赤外放射層、および前記光反射層の順に積層して成る放射冷却装置を用いて、赤外光を前記紫外反射層の前記赤外放射層と接する面とは反対側の放射面から放射する放射冷却方法。 An ultraviolet reflection layer that reflects ultraviolet light, a light reflection layer that reflects visible light and infrared light, an infrared radiation layer that emits infrared light, the ultraviolet reflection layer, the infrared radiation layer, and A radiation cooling method of emitting infrared light from a radiation surface opposite to a surface in contact with the infrared radiation layer of the ultraviolet reflection layer, using a radiation cooling device formed by laminating a light reflection layer in order.
  10. 　前記放射面を空に向け、当該空に向けた放射面から放射する請求項９に記載の放射冷却方法。 The radiation cooling method according to claim 9, wherein the radiation surface is directed to the sky, and radiation is emitted from the radiation surface directed to the sky.
PCT/JP2018/007819 2017-03-28 2018-03-01 Radiative cooling device and radiative cooling method WO2018180177A1 (en)

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