A flexible and scalable solution for daytime passive radiative cooling using polymer sheets

Lin, Kaixin; Chao, Luke; Ho, Tsz Chung; Lin, Chongjia; Chen, Siru; Du, Yuwei; Huang, Baoling; Tso, Chi Yan

doi:10.1016/j.enbuild.2021.111400

Cited by 27 publications

(12 citation statements)

References 49 publications

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“…Beer’s law was applied with I 0 ′ (eq ) and since ε, τ, and ρ can be characterized, both I f and I 0 ′ can be defined. Thus, the following equations were derived from eqs and . I 0 ( 1 − ρ ) e − α t = τ I 0 α = prefix− ln ( τ 1 − ρ ) t FT-IR with an integrating sphere coated with gold is commonly utilized to evaluate the ε in the IR wavelength regime (2.5–14 μm). − ,,,− ,,,, The α values of various polymers were plotted as a function of wavelength using eq , and PDMS and PVDF, which were widely studied as radiative-cooling materials, showed high α values across the wavelength regime for an atmospheric window (7–14 μm). Furthermore, PE has an extremely low α value, which indicates that it rarely absorbs IR radiation .…”

Section: Resultsmentioning

confidence: 99%

“…In terms of designing materials for radiative cooling, multilayer structures composed of ceramic and thin metal layers are often employed to enhance the selective infrared radiation (IR) emissivity. , Additionally, it is proposed to utilize polymers with high IR emissivity. It is well known that poly(dimethylsiloxane) (PDMS), ,− poly(vinylidene fluoride) (PVDF), ,− poly(tetrafluoroethylene) (PTFE), , poly(methylmethacrylate) (PMMA), , and cellulose − can absorb/emit over 90% of the IR regime ranging between 7 and 14 μm wavelength (atmospheric window). These polymer layers (∼5 mm thickness) are paired with metal plates ,,,, or porous structures ,,,,,− , to enable not only high IR emissivity but also high solar reflectance for outdoor applications.…”

Section: Introductionmentioning

confidence: 99%

“…It is well known that poly(dimethylsiloxane) (PDMS), ,− poly(vinylidene fluoride) (PVDF), ,− poly(tetrafluoroethylene) (PTFE), , poly(methylmethacrylate) (PMMA), , and cellulose − can absorb/emit over 90% of the IR regime ranging between 7 and 14 μm wavelength (atmospheric window). These polymer layers (∼5 mm thickness) are paired with metal plates ,,,, or porous structures ,,,,,− , to enable not only high IR emissivity but also high solar reflectance for outdoor applications. Numerous trials on producing porous geometries in radiative-cooling polymers by stacking fibers, ,, utilizing phase separation of the evaporative solvent, , and expanding the polymer film have been reported.…”

Section: Introductionmentioning

confidence: 99%

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Radiative-Cooling Composites with Enhanced Infrared Emissivity by Structural Infrared Scattering through Indium Tin Oxide Nanoparticles in a Polymer Matrix

Park

Pal

Otoufat

et al. 2023

ACS Appl. Mater. Interfaces

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Radiative cooling has attracted tremendous interest as it can tackle global warming by saving energy consumption in heating, ventilation, and air conditioning (HVAC) in buildings. Polymer materials play an important role in radiative cooling owing to their high infrared emissivity. Along this line, numerous studies on optically optimized geometries were carried out to enhance the selective wavelength absorption for high infrared emissivity; however, the polymer material itself relatively was not investigated and optimized enough. Herein, we investigate the infrared radiation (IR) absorption coefficient of various polymer types, and introduce a new concept of radiative-cooling composites. By dispersing the IR scattering medium in a polymer matrix, IR can be effectively scattered and attenuated by the polymer matrix. Indium tin oxide was utilized as the IR scattering medium in a cellulose acetate polymer matrix in this report. The window film was made with this composite and showed an effective cooling performance by outdoor thermal evaluation. This composite opens a new venue to endow materials with enhanced radiative-cooling property regardless of the polymer types.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Radiative-Cooling Composites with Enhanced Infrared Emissivity by Structural Infrared Scattering through Indium Tin Oxide Nanoparticles in a Polymer Matrix

Park

Pal

Otoufat

et al. 2023

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

show abstract

“…Lack of temperature preservation ability of radiation cooling materials, and the side-effect of non-radiative heat absorption, seriously limits the application of passive radiation cooling materials. By enhancing the thermal resistance of the bottom surface [ 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ] and enlarging the radiation channel of the top surface, designing a multi-layer materials structure is a worthy solution to break the application limitations of radiation cooler. Wang et al [ 62 ] prepared ultra-high foaming rate polyethylene aerogel with high solar reflectivity (92.2%, 6 mm thickness), high infrared transmittance (79.9%, 6 mm thickness), low thermal conductivity (28 mW/m/K) and was excellently insulated.…”

Section: Introductionmentioning

confidence: 99%

A Scalable Heat Pump Film with Zero Energy Consumption

et al. 2022

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Radiative cooling is an effective technology with zero energy consumption to alleviate climate warming and combat the urban heat island effect. At present, researchers often use foam boxes to isolate non-radiant heat exchange between the cooler and the environment through experiments, so as to achieve maximum cooling power. In practice, however, there are challenges in setting up foam boxes on a large scale, resulting in coolers that can be cooled below ambient only under low convection conditions. Based on polymer materials and nano-zinc oxide (nano-ZnO, refractive index > 2, the peak equivalent spherical diameter 500 nm), the manufacturing process of heat pump film (HPF) was proposed. The HPF (4.1 mm thick) consists of polyethylene (PE) bubble film (heat transfer coefficient 0.04 W/m/K, 4 mm thick) and Ethylene-1-octene copolymer (POE) cured nano-ZnO (solar reflectance ≈94% at 0.075 mm thick). Covering with HPF, the object achieves 7.15 °C decreasing in normal natural environment and 3.68 °C even under certain circumstances with high surface convective heat transfer (56.9 W/m2/K). HPF has advantages of cooling the covered object, certain strength (1.45 Mpa), scalable manufacturing with low cost, hydrophobic characteristics (the water contact angle, 150.6°), and meeting the basic requirements of various application scenarios.

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“…As a result, daytime radiative coolers always demonstrate low absorptivity in the solar spectrum regions and high emissivity in the mid-infrared wavelength region. Recently, many works have been published and display different designs of daytime radiative coolers, such as multilayer photonic structures, ,, porous polymer structures, − nanocomposite-based films, − and metamaterials. − As an energy-saving and potential cooling technology, passive daytime radiative cooling has broad prospects in numerous fields, including building cooling, textiles cooling, and efficient solar cells. − …”

mentioning

confidence: 99%

Phase Change Material Enhanced Radiative Cooler for Temperature-Adaptive Thermal Regulation

Yang

Zhong

et al. 2023

ACS Nano

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Passive radiative cooling (PRC), as an electricity-free and environmentally friendly cooling strategy, is highly desirable in improving the global energy landscape. Despite numerous efforts, most designs for PRC are so devoted to improving the cooling performance in the daytime that they neglect the triggered overcooling at night. Herein, we approached an effective design for temperature-adaptive thermal management through integrating PRC and temperature control of room-temperature phase change material. Compared with conventional radiative coolers, the developed phase change material-enhanced radiative cooler (PCMRC) can adjust its performance according to the temperature of day and night. The PCMRC achieved an average subambient temperature drop of ∼6.3 °C under direct sunlight and an average temperature rise of ∼2.1 °C above ambient temperature at night, as well as a reduced temperature difference between day and night. The temperature-adaptive PCMRC shows great promise for passive radiative cooling regulation, which can further extend the applications of passive radiative cooling.

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A flexible and scalable solution for daytime passive radiative cooling using polymer sheets

Cited by 27 publications

References 49 publications

Radiative-Cooling Composites with Enhanced Infrared Emissivity by Structural Infrared Scattering through Indium Tin Oxide Nanoparticles in a Polymer Matrix

Radiative-Cooling Composites with Enhanced Infrared Emissivity by Structural Infrared Scattering through Indium Tin Oxide Nanoparticles in a Polymer Matrix

A Scalable Heat Pump Film with Zero Energy Consumption

Phase Change Material Enhanced Radiative Cooler for Temperature-Adaptive Thermal Regulation

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