Temperature-Adaptive Radiative Cooling Device
Context:
As the global energy crisis deepens and climate change accelerates, the need for sustainable energy management solutions becomes increasingly urgent. One promising innovation is passive radiative cooling.
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- As reported in Advanced Photonics, researchers at the Beijing Institute of Technology have developed a new type of temperature-adaptive radiative cooling device that dynamically adjusts its cooling performance in response to changes in ambient temperature.
- This innovation represents a significant step forward in optimising cooling efficiency while minimising energy use.
About
- Passive Radiative Cooling is a technology that enables objects to release heat directly into space without consuming additional energy, offering a potential breakthrough in energy-efficient cooling.
- Radiative cooling materials must exhibit both high solar reflectivity and emissivity for effective performance.
- While numerous radiative cooling materials have been developed, most feature static emissivity.
- This means that even in low ambient temperatures, they maintain strong cooling capabilities, leading to “overcooling,” which can increase the energy demand of heating systems.
- In contrast, thermochromic phase-change materials are ideal for dynamic radiative cooling, as they adjust their properties based on temperature without requiring any power source, circuits, or moving parts.
- This recent advancement builds on previous research involving vanadium dioxide (VO2), a material known for its ability to switch between thermal radiation states.
Vanadium(IV) oxide, commonly known as vanadium dioxide (VO2), is an inorganic compound with the chemical formula VO2. It appears as a dark blue solid and exhibits amphoteric behaviour, meaning it can dissolve in non-oxidizing acids to form the blue vanadyl ion and in alkaline solutions to produce the brown ion, or the ion at high pH.
VO2 has potential applications in memory devices, phase-change switches, and passive radiative cooling technologies, including smart windows and roofs that can cool or heat depending on the temperature. It is also relevant in aerospace communication systems and neuromorphic computing. In nature, VO2 occurs as the mineral paramontroseite.
- The new design features a metasurface with an array of VO2 squares, enhancing the device’s performance by balancing high thermal emissivity with low solar absorptance.
- The device, called the Temperature-Adaptive Metasurface Radiative Cooling Device (ATMRD), significantly improves over earlier models.
- It achieves a solar absorptance of 27.71%—7.54% lower than previous designs—and an emissivity of 0.85 at high temperatures, which is 13.3% higher.
- Additionally, its emissivity modulation is 20% more efficient, making it better at responding to temperature changes.
