Radiative Cooling Structure for Illuminated Objects
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Solution Overview
Problem
Structures such as solar cells heat up under sunlight, leading to reduced efficiency and reliability due to undesirably high temperatures, and existing methods struggle to effectively illuminate objects while controlling temperature.
Innovation Solution
A structure transparent at solar wavelengths and emissive in the atmospheric electromagnetic radiation transparency window is used to pass light for illumination and radiatively cool objects, preserving their color and reducing temperature through thermal radiation emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If sunlight is provided to an object for illumination, then the object is illuminated, but the object heats up to temperatures substantially above ambient air temperatures
Solution Approach 1:
The electromagnetic spectrum is segmented into different wavelength ranges with distinct optical properties. The object is designed to reflect solar wavelengths (0.3-2.5 μm) for illumination while emitting thermal radiation in the atmospheric transparency window (8-13 μm), separating the illumination and cooling functions spectrally.
Solution Approach 2:
The optical properties of the object are optimized by changing parameters such as surface coating materials and spectral reflectivity/emissivity characteristics. The object maintains high reflectivity in the solar spectrum while achieving high emissivity in the thermal infrared range, enabling simultaneous illumination and cooling.
2Productivity
If the object's temperature is reduced through cooling, then efficiency is enhanced, but illumination may be compromised
Solution Approach 1:
The atmospheric electromagnetic radiation transparency window (8-13 μm) acts as an intermediary channel for heat dissipation. This wavelength band allows thermal radiation to pass through the atmosphere to space, providing a dedicated cooling pathway that does not interfere with visible illumination in the solar spectrum.
Solution Approach 2:
Different regions of the electromagnetic spectrum are assigned different functional qualities: the solar spectrum (0.3-2.5 μm) is optimized for illumination with high reflectivity, while the thermal infrared range (8-13 μm) is optimized for radiative cooling with high emissivity, allowing simultaneous optimization of both functions.
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
This approach achieves significant temperature reduction, maintaining the object's color and enhancing efficiency by providing energy-free, passive cooling, even in the presence of convective and conductive heat exchange, with a non-radiative heat exchange coefficient as high as 40 W/m2/K, reducing the object's temperature by up to 31.4 K.
Implementation Method 1
The second structure operates with the first structure to pass light into the first structure for illuminating the object
Implementation Method 2
The second structure is transparent at solar wavelengths and emissive in the atmospheric electromagnetic radiation transparency window
Implementation Method 3
to radiatively cool the object while preserving the object's color
Data Source
AI summary
Aspects of the present disclosure are directed to providing and/or controlling electromagnetic radiation. As may be implemented in accordance with one or more embodiments, an apparatus includes a first structure that contains an object, and a second structure that is transparent at solar wavelengths and emissive in the atmospheric electromagnetic radiation transparency window. The second structure operates with the first structure to pass light into the first structure for illuminating the object, and to radiatively cool the object while preserving the object's color.