Metamaterial Radiative Cooling Panel for Waterless Dry Cooling
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Solution Overview
Problem
Current passive radiative cooling technologies are not commercially viable for large-scale dry cooling of power plants in hot or humid regions, as they are either expensive or not scalable, and existing solutions fail to meet the criteria for high-performance radiative cooling, which includes reflecting solar light, emitting at atmospheric transparency windows, and minimizing convection.
Innovation Solution
A low-cost passive radiative cooling panel design featuring a reflective layer over an emitter layer with metamaterial nanostructures that dissipate heat as radiant energy, where the emitter layer is configured to emit at atmospheric transparency windows and the reflective layer reflects solar radiation, facilitating efficient heat dissipation without power input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional dry cooling systems are used, then water consumption is reduced, but the cooling area required and operating costs increase significantly
Solution Approach 1:
The invention changes the thermal radiation parameters of the cooling panel by incorporating metamaterials with specific emissivity characteristics. The panel is designed to have high emissivity (ε>0.9) in the atmospheric transparency window (8-13μm) to maximize radiative heat transfer, while maintaining low solar absorptivity (α<0.1) to minimize heat gain. This parameter optimization enables the panel to achieve high cooling power density without requiring large area.
2Loss of substance
If passive radiative cooling technology is implemented, then cooling power is achieved without water consumption, but the technology is either expensive or not scalable for large-scale power plant cooling
Solution Approach 1:
The cooling panel is segmented into distinct functional layers: a selective radiation-absorbing/emitting layer with metamaterials optimized for atmospheric window emission, and a reflective layer to minimize solar heat gain. This segmentation allows each layer to be optimized independently for its specific function, enabling cost-effective manufacturing through specialized material selection and simplified production processes for large-scale deployment.
3Temperature
If high-performance passive radiative cooling is achieved, then solar light reflection and atmospheric window emission are optimized, but device complexity increases
Solution Approach 1:
The invention employs composite material structures combining metamaterials with selective radiation properties and reflective materials. The composite structure integrates a radiation-emitting layer with high emissivity in the atmospheric window (8-13μm) and a reflective layer with low solar absorptivity. This composite approach achieves high cooling performance through material property optimization rather than complex geometric structures, thereby reducing overall device complexity while maintaining effectiveness.
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 solution achieves net cooling powers of up to 75 W/m² during the day and 130 W/m² at night, with a prototype demonstrating a 6°C cooling of an aluminum substrate in broad daylight, meeting the criteria for high-performance passive radiative cooling while being cost-effective and scalable.
Implementation Method 1
the emitter layer is configured to emit, with an emissivity close to unity, radiant energy having wavelengths/frequencies that fall within one or more atmospheric transparency windows
Implementation Method 2
emitted 'ATW radiant energy' has wavelengths in the range of 8μm to 13μm, and/or in the range of 16-28μm, which are two known atmospheric transparency windows
Implementation Method 3
the reflective layer is configured to reflect at least 94% of incident solar light (i.e., solar radiation having a frequencies of 2μm or less)
Implementation Method 4
the emitter layer includes metamaterial nanostructures (i.e., subwavelength engineered structures with tailored optical properties) that are configured to dissipate heat in the form of emitted radiant energy
Data Source
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Figure 2A~2B
Figure 3~4
AI summary
According to one aspect there is provided a passive radiative cooling panel comprising: an emitter layer including an ultra-black material that is configured to convert thermal energy into radiant energy such that at least a portion of said radiant energy has wavelengths in the range of 8µm to 13µm, said ultra-black material being further configured such that said portion of said radiant energy is generated with an emissivity of at least 0.998; and an upper layer disposed to receive said radiant energy on a lower surface thereof, said upper layer being configured to reflect incident solar radiation directed onto an upper surface thereof, said upper layer further configured to pass therethrough said portion of said radiant energy having wavelengths in the range of 8µm to 13µm such that said emitted radiant energy portion is transmitted from said upper surface.