Radiative cooling device
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Solution Overview
Problem
Existing radiative cooling devices face challenges in achieving low attainable temperatures due to heat inflow from the atmosphere and heat conduction from components such as heat radiators and light transmitting plates.
Innovation Solution
A radiative cooling device is designed with a far-infrared radiator and a far-infrared transmitting window member, both optimized for specific wavelength ranges, along with an intermediate heat insulating member that reduces heat conduction and inflow by transmitting far-infrared rays while minimizing solar radiation absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat radiator contacts the atmosphere, then heat exchange with the environment is enabled, but heat inflow from the atmosphere causes an increase in the attainable temperature at cooling
Solution Approach 1:
The device segments the heat radiator into multiple independent plates (first heat radiator plate and second heat radiator plate) with selective surfaces facing different directions. This segmentation allows each plate to handle specific heat exchange functions independently, reducing overall heat inflow while maintaining cooling effectiveness.
Solution Approach 2:
Different surfaces of the heat radiator plates are provided with different selective surfaces having specific spectral characteristics. The first selective surface is optimized for radiating heat upward, while the second selective surface is optimized for radiating heat downward, allowing localized optimization of heat exchange in different directions to minimize heat inflow.
2Temperature
If the light transmitting plate covers the opening, then thermal insulation is improved, but heat conduction from the plate to the heat radiator causes an increase in the attainable temperature at cooling
Solution Approach 1:
An intermediate heat insulating member is introduced between the light transmitting plate and the heat radiator. This intermediary component provides thermal insulation to block heat conduction from the plate to the radiator, while still allowing far-infrared rays to pass through, thus maintaining cooling effectiveness while reducing heat inflow.
Solution Approach 2:
The light transmitting plate is constructed as a composite structure with a base plate and a far-infrared transmitting layer. This composite material allows the plate to transmit far-infrared radiation while providing thermal insulation properties to reduce heat conduction to the heat radiator.
3Temperature
If the heat insulating container provides thermal insulation, then heat loss from the object is reduced, but heat inflow from the atmosphere through the container increases the attainable temperature at cooling
Solution Approach 1:
The heat insulating container is provided with heat insulating layers at specific locations where heat inflow is most significant, such as the bottom and side walls. These localized insulation measures effectively reduce heat inflow from the atmosphere while maintaining the overall thermal insulation performance of the container.
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 achieves lower attainable temperatures by effectively radiating far-infrared rays into the atmosphere, reducing heat inflow and conduction, and maintaining high transmittance and reflectance properties to enhance cooling efficiency.
Implementation Method 1
a far-infrared radiator that is arranged between the object and the opening portion in the heat insulating container, that thermally contacts the object, and that radiates far-infrared rays in a wavelength range of from 8 μm to 13 μm
Implementation Method 2
a far-infrared transmitting window member that closes at least a part of the opening portion of the heat insulating container and that transmits the far-infrared rays radiated from the far-infrared radiator
Implementation Method 3
an intermediate heat insulating member that is arranged between the far-infrared transmitting window member and the far-infrared radiator, that thermally insulates the far-infrared transmitting window member and the far-infrared radiator from each other, and that transmits the far-infrared rays radiated from the far-infrared radiator
Data Source
AI summary
A radiative cooling device including: a heat insulating container having an opening portion, and being configured to house an object to be cooled at an interior thereof and thermally insulates the object from an exterior thereof; a far-infrared radiator that is arranged between the object and the opening portion in the heat insulating container, that thermally contacts the object, and that radiates far-infrared rays in a wavelength range of from 8 μm to 13 μm; a far-infrared transmitting window member that closes at least part of the opening portion of the heat insulating container and that transmits the far-infrared rays radiated from the far-infrared radiator; and an intermediate heat insulating member that is arranged between the far-infrared transmitting window member and the far-infrared radiator, that thermally insulates the far-infrared transmitting window member and the far-infrared radiator from each other, and that transmits the far-infrared rays radiated from the far-infrared radiator.