Daytime passive radiative cooling by ultra emissive bio-inspired polymeric surface

Jeong, Shinyoung; Tso, Chi Yan; Wong, Yue Him; Chao, Christopher Yu Hang; Huang, Baoling

doi:10.1016/j.solmat.2019.110296

Cited by 159 publications

(74 citation statements)

References 53 publications

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“…The key to achieve a lower temperature than that of the surroundings even under direct sunlight is to have a high reflectivity to repel incoming sunlight (wavelength 0.3 to 2.5 μm) and a high thermal emissivity to radiate heat to outer space in the transparent atmospheric spectral window (TASW; 8 to 13 μm) (12)(13)(14)(15)(16)(17). In recent years, there have been several proposals and demonstrations of photonic structures for controlling both solar reflection and thermal emission by manipulating light-matter interactions at subwavelength scales (18)(19)(20)(21)(22)(23)(24). Rephaeli et al (18) proposed a planar photonic structure capable of realizing passive radiative sky cooling.…”

mentioning

confidence: 99%

Biologically inspired flexible photonic films for efficient passive radiative cooling

Zhang

Liu

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

368

236

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Temperature is a fundamental parameter for all forms of lives. Natural evolution has resulted in organisms which have excellent thermoregulation capabilities in extreme climates. Bioinspired materials that mimic biological solution for thermoregulation have proven promising for passive radiative cooling. However, scalable production of artificial photonic radiators with complex structures, outstanding properties, high throughput, and low cost is still challenging. Herein, we design and demonstrate biologically inspired photonic materials for passive radiative cooling, after discovery of longicorn beetles’ excellent thermoregulatory function with their dual-scale fluffs. The natural fluffs exhibit a finely structured triangular cross-section with two thermoregulatory effects which effectively reflects sunlight and emits thermal radiation, thereby decreasing the beetles’ body temperature. Inspired by the finding, a photonic film consisting of a micropyramid-arrayed polymer matrix with random ceramic particles is fabricated with high throughput. The film reflects ∼95% of solar irradiance and exhibits an infrared emissivity >0.96. The effective cooling power is found to be ∼90.8 W⋅m−2and a temperature decrease of up to 5.1 °C is recorded under direct sunlight. Additionally, the film exhibits hydrophobicity, superior flexibility, and strong mechanical strength, which is promising for thermal management in various electronic devices and wearable products. Our work paves the way for designing and fabrication of high-performance thermal regulation materials.

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mentioning

confidence: 99%

Biologically inspired flexible photonic films for efficient passive radiative cooling

Zhang

Liu

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

368

236

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“…To evaluate the base case further, the reflective coating was added to all pitched roof constructions (on gray-colored buildings) for comparison purposes to the proposed case. The value of the coating was based on the value of the reflective properties of the Saharan ant 0.97 [ 43 ], commercially a high value of reflective coating of 0.92 [ 44 ] was found and therefore that value was taken which was the closest.…”

Section: Methodsmentioning

confidence: 99%

“…Infrared photo with the respective surface temperature variations ( left ). Characteristics of the Saharan ant ( right ) ([ 41 , 43 ]).…”

Section: Figurementioning

confidence: 99%

Numerical Assessment of Zebra-Stripes-Based Strategies in Buildings Energy Performance: A Case Study under Tropical Climate

et al. 2022

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Urban growth has increased the risk of over-heating both in the microclimate and inside buildings, affecting thermal comfort and energy efficiency. That is why this research aims to evaluate the energy performance of buildings in terms of thermal comfort (operative temperature (OP) levels, satisfied hours of natural ventilation SHNV, thermal lag), and energy efficiency (roof heat gains and surface temperatures) in an urban area in Panama City, using superficial-heat-dissipation biomimetic strategies. Two case studies, a base case and a proposed case, were evaluated using the Designbuilder software through dynamic simulation. The proposed case is based on a combined biomimetic strategy; the reflective characteristics of the Saharan ant applied as a coating on the roofs through a segmented pattern such as the Zebra’s stripes (one section with coating, and another without). Results showed that the OP decreased from 8 to 10 °C for the entire urban zone throughout the year. A reduction of 3.13% corresponding to 8790 kWh per year was achieved for cooling energy consumption. A difference of 5 °C in external surface temperature was obtained, having a lower temperature in which the biomimetic strategy was applied. Besides, it was evidenced that a contrasted-reflectivity-stripes pitched roof performed better than a fully reflective roof. Thus, the functionality of Zebra stripes, together with the reflective characteristics of the Saharan ant, provide better performance for buildings’ thermal regulation and energy needs for cooling.

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“…Layered material structures have costly manufacturing as it involves manufacturing methods like E-Beam evaporation, sputtering, etc. The other structures of material are the distribution of nano/microparticles into the polymer, stand-alone nanoparticles with some binder 22 , 23 . PVDF polymer has been taken as the base material as it is lossless in the solar spectrum to achieve reflection that efficiently works for passive radiative cooling.…”

Section: Materials For Passive Radiative Coolingmentioning

confidence: 99%

Performance simulation of polymer-based nanoparticle and void dispersed photonic structures for radiative cooling

Bijarniya

Sarkar

Maiti

2021

Sci Rep

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Passive radiative cooling is an emerging field and needs further development of material. Hence, the computational approach needs to establish for effective metamaterial design before fabrication. The finite difference time domain (FDTD) method is a promising numerical strategy to study electromagnetic interaction with the material. Here, we simulate using the FDTD method and report the behavior of various nanoparticles (SiO2, TiO2, Si3N4) and void dispersed polymers for the solar and thermal infrared spectrums. We propose the algorithm to simulate the surface emissive properties of various material nanostructures in both solar and thermal infrared spectrums, followed by cooling performance estimation. It is indeed found out that staggered and randomly distributed nanoparticle reflects efficiently in the solar radiation spectrum, become highly reflective for thin slab and emits efficiently in the atmospheric window (8–13 µm) over the parallel arrangement with slight variation. Higher slab thickness and concentration yield better reflectivity in the solar spectrum. SiO2-nanopores in a polymer, Si3N4 and TiO2 with/without voids in polymer efficiently achieve above 97% reflection in the solar spectrum and exhibits substrate independent radiative cooling properties. SiO2 and polymer combination alone is unable to reflect as desired in the solar spectrum and need a highly reflective substrate like silver.

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Daytime passive radiative cooling by ultra emissive bio-inspired polymeric surface

Cited by 159 publications

References 53 publications

Biologically inspired flexible photonic films for efficient passive radiative cooling

Biologically inspired flexible photonic films for efficient passive radiative cooling

Numerical Assessment of Zebra-Stripes-Based Strategies in Buildings Energy Performance: A Case Study under Tropical Climate

Performance simulation of polymer-based nanoparticle and void dispersed photonic structures for radiative cooling

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