Radiative cooling device and radiative cooling method
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Solution Overview
Problem
Conventional radiative cooling devices lack flexibility due to inorganic protective layers, which crack or peel off when attached to flexible surfaces, and are prone to deterioration and discoloration of reflective layers under solar radiation, leading to ineffective cooling.
Innovation Solution
A radiative cooling device with a resin material layer and a protective layer formed from polyolefin based resin or ethylene terephthalate resin, along with a light reflective layer containing silver or silver alloy, designed to reflect sunlight and prevent discoloration, ensuring flexibility and effective cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inorganic protective layer (aluminum oxide or silicon dioxide) is used, then the protective function is provided, but the device lacks flexibility and the layer cracks or peels off when attached to flexible surfaces
Solution Approach 1:
The protective layer material is changed from inorganic materials (aluminum oxide, silicon dioxide) to organic resin materials (acrylic resin, polyurethane resin, polyester resin). This parameter change in material composition maintains the protective function while providing flexibility, allowing the layer to bend without cracking or peeling when attached to flexible surfaces.
2Adaptability or versatility
If a thin protective layer (50 nm polymethylmethacrylate) is used, then flexibility is maintained, but the layer deteriorates quickly under solar radiation and causes discoloration of the silver reflective layer
Solution Approach 1:
The protective layer material is changed from polymethylmethacrylate to resin materials with superior UV resistance (acrylic resin, polyurethane resin, polyester resin). This parameter change in material composition maintains flexibility while significantly improving durability under solar radiation, preventing deterioration and discoloration of the silver reflective layer.
Solution Approach 2:
The protective layer is formed from composite resin materials that combine flexibility with enhanced UV resistance properties. These composite materials provide both the required flexibility for flexible substrates and the durability to withstand solar radiation without causing discoloration of the underlying silver reflective layer.
3Adaptability or versatility
If the protective layer follows the flexibility of the infrared radiative layer, then flexibility is maintained, but the protective layer cracks or peels off and loses its protective function
Solution Approach 1:
The protective layer material is changed from inorganic materials to flexible organic resin materials that can elastically deform. This parameter change allows the protective layer to follow the flexibility of the infrared radiative layer while maintaining structural integrity, preventing cracks and peeling even when bent or deformed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device maintains flexibility and cooling efficiency under solar radiation by suppressing discoloration of the reflective layer and reflecting sunlight, allowing effective radiative cooling even in outdoor environments.
Implementation Method 1
the light reflective layer reflects light (ultraviolet light, visible light, infrared light) transmitted through an infrared radiative layer
Implementation Method 2
a radiative cooling device including an infrared radiative layer that radiates infrared light from a radiative surface
Implementation Method 3
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
Data Source
AI summary
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.