Radiative cooling to low temperatures with selectivity IR-emitting surfaces

Granqvist, Claes G.; Hjortsberg, A.; Eriksson, Thomas

doi:10.1016/0040-6090(82)90648-4

Cited by 83 publications

(48 citation statements)

References 8 publications

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“…The SiO cooler cooled to 13.8°C below ambient, while the blackbody cooler cooled to 13.4°C below ambient [2]. Therefore, a stronger cooler consists of silicon nitride (Si 3 N 4 ), and the Al back reflector was fabricated in the following work [10]. Si 3 N 4 has been explored again in a more recent work, showing a capability of sub-freezing temperature cooling (−22.2°C) [47].…”

Section: Bulk and Gaseous Materials Radiative Coolersmentioning

confidence: 99%

“…Fortunately, emittance properties approaching these ideals can be found in bulk materials suitable for massive production. They have been extensively studied in pioneering works of the 1970s and 1980s [1,2,5,6,10,11,42,[51][52][53][54][55][56][57]. Similar to bulk materials, gaseous materials such as ethylene and ammonia have also been proposed to be radiative coolers [56,58,59].…”

Section: Radiative Cooling Materials and Structuresmentioning

confidence: 99%

“…The earliest adoption of radiative cooling has been traced back to the courtyard architectures of ancient Iran [4]. In the modern era, the first scientific studies found that certain materials have potential for limited selectivity, notably polymeric materials [5,6], titanium dioxide [7][8][9], silicon nitrides [10], and silicon monoxide (SiO) [11]. While cooling to 40°C below ambient with SiO is theoretically possible [11], the temperature difference is much smaller in experiments [2].…”

Section: Introductionmentioning

confidence: 99%

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Radiative sky cooling: fundamental physics, materials, structures, and applications

et al. 2017

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Radiative sky cooling reduces the temperature of a system by promoting heat exchange with the sky; its key advantage is that no input energy is required. We will review the origins of radiative sky cooling from ancient times to the modern day, and illustrate how the fundamental physics of radiative cooling calls for a combination of properties that may not occur in bulk materials. A detailed comparison with recent modeling and experiments on nanophotonic structures will then illustrate the advantages of this recently emerging approach. Potential applications of these radiative cooling materials to a variety of temperature-sensitive optoelectronic devices, such as photovoltaics, thermophotovoltaics, rectennas, and infrared detectors, will then be discussed. This review will conclude by forecasting the prospects for the field as a whole in both terrestrial and space-based systems.

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Section: Bulk and Gaseous Materials Radiative Coolersmentioning

confidence: 99%

Section: Radiative Cooling Materials and Structuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Radiative sky cooling: fundamental physics, materials, structures, and applications

et al. 2017

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“…Apart from the polymer fi lms, pigmented paints, naturally available inorganic compounds and gases with IR emission were also investigated for nocturnal radiative cooling applications. [ 18,[20][21][22]24,31,32,46,[48][49][50][51] The early demonstration of using pigmented paints reported signifi cant cooling during the night under clear sky conditions. [ 18 ] Commercially available white paint containing titanium dioxide (TiO 2 ) was coated on aluminum plates and was used as the IR radiator.…”

Section: Ir Radiatorsmentioning

confidence: 99%

“…[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] The use of bulk materials comprising intrinsic infrared (IR) emissions for considerable radiative cooling were discussed earlier. [ 10,18,21,23,24 ] However, radiative cooling was mostly limited during the nighttime as suitable materials with high IR emission within the atmospheric window and yet delivering strong solar refl ection during the day was not achieved. Although some solar refl ecting materials were reported, daytime cooling below the ambient temperature was not achieved as the absorbed solar energy exceeded the emitted energy by thermal radiation.…”

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confidence: 99%

Radiative Cooling: Principles, Progress, and Potentials

2016

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The recent progress on radiative cooling reveals its potential for applications in highly efficient passive cooling. This approach utilizes the maximized emission of infrared thermal radiation through the atmospheric window for releasing heat and minimized absorption of incoming atmospheric radiation. These simultaneous processes can lead to a device temperature substantially below the ambient temperature. Although the application of radiative cooling for nighttime cooling was demonstrated a few decades ago, significant cooling under direct sunlight has been achieved only recently, indicating its potential as a practical passive cooler during the day. In this article, the basic principles of radiative cooling and its performance characteristics for nonradiative contributions, solar radiation, and atmospheric conditions are discussed. The recent advancements over the traditional approaches and their material and structural characteristics are outlined. The key characteristics of the thermal radiators and solar reflectors of the current state‐of‐the‐art radiative coolers are evaluated and their benchmarks are remarked for the peak cooling ability. The scopes for further improvements on radiative cooling efficiency for optimized device characteristics are also theoretically estimated.

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A Solution‐Processed Inorganic Emitter with High Spectral Selectivity for Efficient Subambient Radiative Cooling in Hot Humid Climates

et al. 2022

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centuries, it was only recently that noontime cooling was first demonstrated using a multilayer photonic structure. [2] In tropical and subtropical areas, the demand for cooling is particularly huge due to high ambient temperatures. However, it is proved that daytime cooling is difficult to achieve in such areas with stronger solar irradiation and higher humidity than mid-latitude regions. [3][4][5][6][7] With the increase in humidity, the transmittances within the atmospheric windows remarkably decrease, while most secondary windows such as the 16-25 µm window may even disappear in humid climates (Figure S1, Supporting Information). This significantly increases the atmospheric radiation and limits the cooling capability of radiative coolers, especially those with strong IR absorption/emission beyond the major atmospheric window. Although broadband IR emitters may provide ≈10% higher cooling power potential than selective ones in less humid climates due to the existence of secondary windows, in humid areas with high precipitable water vapor (PWV), this advantage vanishes and their cooling temperatures are notably limited by broadband IR absorption. [8] To maintain applicability in different climates, an ideal daytime radiative cooler should show high emittance only within the main Daytime radiative cooling provides an eco-friendly solution to space cooling with zero energy consumption. Despite significant advances, most state-ofthe-art radiative coolers show broadband infrared emission with low spectral selectivity, which limits their cooling temperatures, especially in hot humid regions. Here, an all-inorganic narrowband emitter comprising a solutionderived SiO x N y layer sandwiched between a reflective substrate and a selfassembly monolayer of SiO 2 microspheres is reported. It shows a high and diffusive solar reflectance (96.4%) and strong infrared-selective emittance (94.6%) with superior spectral selectivity (1.46). Remarkable subambient cooling of up to 5 °C in autumn and 2.5 °C in summer are achieved under high humidity without any solar shading or convection cover at noontime in a subtropical coastal city, Hong Kong. Owing to the all-inorganic hydrophobic structure, the emitter shows outstanding resistance to ultraviolet and water in long-term durability tests. The scalable-solution-based fabrication renders this stable high-performance emitter promising for large-scale deployment in various climates.

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Radiative cooling to low temperatures with selectivity IR-emitting surfaces

Cited by 83 publications

References 8 publications

Radiative sky cooling: fundamental physics, materials, structures, and applications

Radiative sky cooling: fundamental physics, materials, structures, and applications

Radiative Cooling: Principles, Progress, and Potentials

A Solution‐Processed Inorganic Emitter with High Spectral Selectivity for Efficient Subambient Radiative Cooling in Hot Humid Climates

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