Radiative cooling device and radiative cooling method
The radiative cooling device includes an infrared radiative layer A that radiates infrared light IR from a radiative surface H, a light reflective layer B disposed on a side opposite to the radiative surface H with respect to the infrared radiative layer A, and a protective layer D disposed between the infrared radiative layer A and the light reflective layer B. The infrared radiative layer A is a resin material layer J having a thickness adjusted so as to emit a heat radiation energy greater than an absorbed solar energy in a wavelength range from 8 μm to 14 μm. The light reflective layer B contains silver or a silver alloy, and the protective layer D is formed from a polyolefin based resin with a thickness of 300 nm or more and 40 μm or less or an ethylene terephthalate resin with a thickness of 17 μm or more and 40 μm or less.
1. A radiative cooling device comprising:
an infrared radiative layer configured to radiate infrared light from a radiative surface;
a light reflective layer disposed on a side opposite to the radiative surface with respect to the infrared radiative layer; and
a protective layer disposed between the infrared radiative layer and the light reflective layer, and
wherein:
the infrared radiative layer is a resin material layer that has a thickness adjusted so as to emit a heat radiation energy greater than an absorbed solar energy in a wavelength range from 8 μm to 14 μm,
the light reflective layer contains silver or a silver alloy, and
the protective layer is formed from a polyolefin based resin with a thickness of 300 nm or more and 40 μm or less or an ethylene terephthalate resin with a thickness of 17 μm or more and 40 μm or less.
2. The radiative cooling device according to claim 1 ,
wherein the light reflective layer has a reflectance of 90% or more for light having a wavelength within a range from 0.4 μm to 0.5 μm and a reflectance of 96% or more for light having a wavelength longer than 0.5 μm.
3. The radiative cooling device according to claim 1 ,
wherein the thickness of the resin material layer is adjusted such that the resin material layer has:
light absorption properties that satisfy a wavelength average absorptivity of 13% or less in a wavelength range from 0.4 μm to 0.5 μm, a wavelength average absorptivity of 4% or less in a wavelength range from 0.5 μm to 0.8 μm, a wavelength average absorptivity of 1% or less in a wavelength range from 0.8 μm to 1.5 μm, and a wavelength average absorptivity of 40% or less in a wavelength range from 1.5 μm to 2.5 μm; and
heat radiation properties that satisfy a wavelength average emissivity of 40% or more in a wavelength range from 8 μm to 14 μm.
4. The radiative cooling device according to claim 1 ,
wherein a resin material forming the resin material layer is selected from resin materials that have any one or two or more of a carbon-fluorine bond, a siloxane bond, a carbon-chlorine bond, a carbon-oxygen bond, an ether bond, an ester bond, and a benzene ring.
5. The radiative cooling device according to claim 1 ,
wherein a resin material forming the resin material layer contains siloxane as a main component, and
wherein the resin material layer has a thickness of 1 μm or more.
6. The radiative cooling device according to claim 4 ,
wherein the resin material layer has a thickness of 10 μm or more.
7. The radiative cooling device according to claim 1 ,
wherein the resin material layer has a thickness of 20 mm or less.
8. The radiative cooling device according to claim 7 ,
wherein a resin material forming the resin material layer is a fluorocarbon resin or silicone rubber.
9. The radiative cooling device according to claim 1 ,
wherein a resin material forming the resin material layer is a resin material that contains, as a main chain, a hydrocarbon that has any one or two or more of a carbon-chlorine bond, a carbon-oxygen bond, an ester bond, an ether bond, and a benzene ring, or a silicone resin that contains a hydrocarbon having 2 or more carbon atoms as a side chain, and
wherein the resin material layer has a thickness of 500 μm or less.
10. The radiative cooling device according to claim 1 ,
wherein a resin material forming the resin material layer is a blend of a resin that has a carbon-fluorine bond or a siloxane bond and a resin that contains a hydrocarbon as a main chain, and the resin material layer has a thickness of 500 μm or less.
11. The radiative cooling device according to claim 1 ,
wherein a resin material forming the resin material layer is a fluorocarbon resin, and
wherein the resin material layer has a thickness of 300 μm or less.
12. The radiative cooling device according to claim 1 ,
wherein a resin material forming the resin material layer is a resin material that has any one or two or more of a carbon-chlorine bond, a carbon-oxygen bond, an ester bond, an ether bond, and a benzene ring, and
wherein the resin material layer has a thickness of 50 μm or less.
13. The radiative cooling device according to claim 1 ,
wherein the resin material forming the resin material layer is a resin material having a carbon-silicon bond, and
wherein the resin material layer has a thickness of 10 μm or less.
14. The radiative cooling device according to claim 1 ,
wherein a resin material forming the resin material layer is a vinyl chloride resin or a vinylidene chloride resin, and
wherein the resin material layer has a thickness of 10 μm or more and 100 μm or less.
15. The radiative cooling device according to claim 1 ,
wherein the light reflective layer is constituted by silver or a silver alloy and has a thickness of 50 nm or more.
16. The radiative cooling device according to claim 1 ,
wherein the light reflective layer has a layered structure constituted by silver or a silver alloy disposed adjacent to the protective layer and aluminum or an aluminum alloy disposed apart from the protective layer.
17. The radiative cooling device according to claim 1 ,
wherein the resin material layer, the protective layer, and the light reflective layer stacked on each other have a film shape.
18. The radiative cooling device according to claim 1 ,
wherein the resin material layer and the protective layer are joined by a joining layer constituted by an adhesive agent or a pressure-sensitive adhesive agent.
19. The radiative cooling device according to claim 18 ,
wherein a filler constituted by an inorganic material is mixed in the resin material layer.
20. The radiative cooling device according to claim 18 ,
wherein irregularities are formed on both of front and rear surfaces of the resin material layer.
21. A radiative cooling method in which the radiative cooling device according to claim 1 is used to radiate the infrared light from the radiative surface disposed on a side opposite to a surface of the resin material layer that is in contact with the light reflective layer, the radiative cooling method comprising:
orienting the radiative surface toward the sky to allow the radiative surface to radiate the infrared light.