Bio-inspired BC aerogel/PVA hydrogel bilayer gel for enhanced daytime sub-ambient building cooling

Zhao, Bencheng; Yue, Xuejie; Tian, Qiong; Qiu, Fengxian; Li, Yuqi; Zhang, Tao

doi:10.1007/s10570-022-04749-6

Cited by 28 publications

(11 citation statements)

References 32 publications

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“…The bilayer gel had high visible reflectance (0.99) and atmospheric window band emissivity (0.86). 81 With the synergistic effect of radiative and evaporative cooling, a temperature difference of 16.4 °C could be obtained for the gel-covered roof.…”

Section: White Surface With Passive Cooling Powermentioning

confidence: 99%

“…A passive cooling coating combining a bacterial cellulose (BC) hydrophobic aerogel (for white appearance) with a poly(vinyl alcohol) (PVA) hydrogel (for evaporative cooling and IR emission) was developed. The bilayer gel had high visible reflectance (0.99) and atmospheric window band emissivity (0.86) . With the synergistic effect of radiative and evaporative cooling, a temperature difference of 16.4 °C could be obtained for the gel-covered roof.…”

Section: General Considerations and Materials Choices For Passive Coo...mentioning

confidence: 99%

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Hydrogel-Based Stimuli-Responsive Radiative and/or Evaporative Cooling Materials for Carbon Neutrality

Shang,

Zhang,

Zhang

et al. 2024

ACS Energy Lett.

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Radiative cooling cools by radiating heat toward outer space. Evaporative cooling cools by dispatching the latent heat of water via evaporation. These two types of cooling operate without additional pollutant generation. Hydrogel is the one substance that can combine the above two cooling strategies and thus holds high promise to facilitate the construction of a carbon neutral society. This review article first documents the basic principles related to passive cooling, evaporative cooling, heat transfer, and light modulation. Then, the general considerations for hydrogel-based cooling materials are summarized. Third, stimuli-responsive hydrogel-based cooling systems are systematically discussed from aspects of operation mechanisms as well as material selections. Lastly, typical applications of hydrogel-based radiative and/or evaporative cooling materials in buildings, electronic devices, and wearable devices are discussed. Challenges for further development of the hydrogel-based cooling materials are discussed as ending remarks.

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Section: White Surface With Passive Cooling Powermentioning

confidence: 99%

Section: General Considerations and Materials Choices For Passive Coo...mentioning

confidence: 99%

Hydrogel-Based Stimuli-Responsive Radiative and/or Evaporative Cooling Materials for Carbon Neutrality

Shang,

Zhang,

Zhang

et al. 2024

ACS Energy Lett.

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“…During the past few years, passive evaporative cooling has witnessed great advances with the progress of water-rich materials, especially for hydrogels. [44,[59][60][61][62] The high enthalpy of water evaporation (over 2200 kJ kg −1 ) can enable the great cooling potential for heat dissipation. Generally, evaporative cooling power mainly depends on water evaporation rate, which can be quantitatively depicted in Figure 2b.…”

Section: Working Principles Of Passive Photovoltaic Coolingmentioning

confidence: 99%

Passive Photovoltaic Cooling: Advances Toward Low‐Temperature Operation

Liu,

Zhou,

Zhou

et al. 2023

Advanced Energy Materials

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With the great increase in installation, photovoltaics will develop as the main power supply source for the world shortly. However, the actual power generation and lifetime of photovoltaics are greatly compromised by the high working temperature under outdoor operation. In this review, the recent advances of four promising passive photovoltaic cooling methods are summarized with the aim to uncover their working principles, cooling performance, and application potential in photovoltaic devices. For radiative cooling, light management strategies with ultraviolet‐photon downshift and sub‐bandgap reflection are discussed in detail to reveal their great potential in reducing photovoltaic working temperature and enhancing power generation. Subsequently, the great cooling benefits of passive evaporative cooling are underlined in terms of its superior cooling power and temperature drop of photovoltaic devices. Moreover, the promising integrated cooling strategy is further highlighted due to its great potential in enhancing electricity production and fresh water supply. Most crucially, the remaining challenges and the authors'r insights are presented to advance the commercial applications of passive cooling methods in photovoltaics.

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“…At present, it has been pointed out that passive radiative cooling coating require a combination of multiple fillers to achieve synergistic effect for improving PDRC performance. − Yun et al analyzed the optical properties and radiative cooling performances of PDRC paints composed of two-material particles (SiO 2 and Al 2 O 3 ) using 2D FDTD simulation, and the fabricated PDRC paints exhibited high solar reflectance (95.8%) and strong long-wave infrared emission (93.7%) in the atmospheric transparency window, achieving a maximum temperature drop of 9.1 °C. The advantage of the synergistic effect of different functions of multiparticles is to play the unique properties of various fillers, such as high emissivity of atmospheric windows, high reflectivity of sunlight, hydrophobic pollution resistance, multicolor, and so on. − In order to further improve the performance of PDRC, especially the thermal conductivity, it is an important way to improve the performance of PDRC by improving the thermal insulation performance of the coating through the synergistic effect of different functions of multiple particles. Silica (SiO 2 ) aerogel, known for its low thermal conductivity, high specific surface area, and porosity, finds extensive application in building insulation due to its excellent thermal insulation properties. , Additionally, SiO 2 aerogel exhibit a strong emissivity within atmospheric window bands owing to their chemical bonding (−O–Si-O−) .…”

Section: Introductionmentioning

confidence: 99%

Highly Optically Selective and Thermally Insulating Porous Calcium Silicate Composite SiO₂ Aerogel Coating for Daytime Radiative Cooling

Han,

Wang,

Han

et al. 2024

ACS Appl. Mater. Interfaces

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Daytime radiative cooling technology offers a lowcarbon, environmentally friendly, and nonpower-consuming approach to realize building energy conservation. It is important to design materials with high solar reflectivity and high infrared emissivity in atmospheric windows. Herein, a porous calcium silicate composite SiO 2 aerogel water-borne coating with strong passive radiative cooling and high thermal insulation properties is proposed, which shows an exceptional solar reflectance of 94%, high sky window emissivity of 96%, and 0.0854 W/m•K thermal conductivity. On the SiO 2 /CaSiO 3 radiative cooling coating (SiO 2 −CS-coating), a strategy is proposed to enhance the atmospheric window emissivity by lattice resonance, which is attributed to the eight-membered ring structure of porous calcium silicate, thereby increasing the atmospheric window emissivity. In the daytime test (solar irradiance 900W/m 2 , ambient temperature 43 °C, wind speed 0.53 m/s, humidity 25%), the temperature inside the box can achieve a cooling temperature of 13 °C lower than that of the environment, which is 30 °C, and the theoretical cooling power is 96 W/m 2 . Compared with the commercial white coating, SiO 2 −CS-coating can save 70 kW•h of electric energy in 1 month, and the energy consumption is reduced by 36%. The work provides a scalable, widely applicable radiative-cooling coating for building comfort, which can greatly reduce indoor temperatures and is suitable for building surfaces.

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Bio-inspired BC aerogel/PVA hydrogel bilayer gel for enhanced daytime sub-ambient building cooling

Cited by 28 publications

References 32 publications

Hydrogel-Based Stimuli-Responsive Radiative and/or Evaporative Cooling Materials for Carbon Neutrality

Hydrogel-Based Stimuli-Responsive Radiative and/or Evaporative Cooling Materials for Carbon Neutrality

Passive Photovoltaic Cooling: Advances Toward Low‐Temperature Operation

Highly Optically Selective and Thermally Insulating Porous Calcium Silicate Composite SiO₂ Aerogel Coating for Daytime Radiative Cooling

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Bio-inspired BC aerogel/PVA hydrogel bilayer gel for enhanced daytime sub-ambient building cooling

Cited by 28 publications

References 32 publications

Hydrogel-Based Stimuli-Responsive Radiative and/or Evaporative Cooling Materials for Carbon Neutrality

Hydrogel-Based Stimuli-Responsive Radiative and/or Evaporative Cooling Materials for Carbon Neutrality

Passive Photovoltaic Cooling: Advances Toward Low‐Temperature Operation

Highly Optically Selective and Thermally Insulating Porous Calcium Silicate Composite SiO2 Aerogel Coating for Daytime Radiative Cooling

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Product

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Highly Optically Selective and Thermally Insulating Porous Calcium Silicate Composite SiO₂ Aerogel Coating for Daytime Radiative Cooling