As an emerging thermal management strategy,dynamic radiative cooling(DRC)technology enables dynamic modulation of spectral radiation properties under varying environmental conditions through the directional design of ...As an emerging thermal management strategy,dynamic radiative cooling(DRC)technology enables dynamic modulation of spectral radiation properties under varying environmental conditions through the directional design of material spectral characteristics.However,a comprehensive review of the basic physical mechanisms of radiative heat transfer in DRC materials and various design principles involved in dynamic radiative thermal regulation is still lacking.This review systematically summarizes recent advances in this field,spanning from fundamental physical principles to intrinsic molecular and electronic mechanisms,and further to representative material systems and multi-band regulation strategies,highlighting the interdisciplinary research achievements and technological innovations.This work outlines the core mechanisms governing the regulation of different spectral bands during radiative heat transfer processes.Then,the main categories of DRC materials are systematically reviewed,including actively responsive structures,passively responsive structures,and multi-stimuli-responsive materials.Furthermore,the challenges faced by current DRC technology and future development trends are summarized and discussed,providing valuable reference and guidance for further research in this field.Although DRC technologies still face significant challenges in material stability,manufacturing processes,and system integration,the continuous advances in related areas and multifunctional materials are expected to broaden the application prospects of DRC in the future.展开更多
Radiative cooling textiles with spectrally selective surfaces offer a promising energy-efficient approach for sub-ambient cooling of outdoor objects and individuals.However,the spectrally selective mid-infrared emissi...Radiative cooling textiles with spectrally selective surfaces offer a promising energy-efficient approach for sub-ambient cooling of outdoor objects and individuals.However,the spectrally selective mid-infrared emission of these textiles significantly hinders their efficient radiative heat exchange with self-heated objects,thereby posing a significant challenge to their versatile cooling applicability.Herein,we present a bicomponent blow spinning strategy for the production of scalable,ultra-flexible,and healable textiles featuring a tailored dual gradient in both chemical composition and fiber diameter.The gradient in the fiber diameter of this textile introduces a hierarchically porous structure across the sunlight incident area,thereby achieving a competitive solar reflectivity of 98.7%on its outer surface.Additionally,the gradient in the chemical composition of this textile contributes to the formation of Janus infrared-absorbing surfaces:The outer surface demonstrates a high mid-infrared emission,whereas the inner surface shows a broad infrared absorptivity,facilitating radiative heat exchange with underlying self-heated objects.Consequently,this textile demonstrates multi-scenario radiative cooling capabilities,enabling versatile outdoor cooling for unheated objects by 7.8℃ and self-heated objects by 13.6℃,compared to commercial sunshade fabrics.展开更多
The study of shortwave(SW) radiation and its interactions with our planet has proven critical for advancing the understanding of the Earth–atmosphere system. Here, the author shares an accessible and high-level persp...The study of shortwave(SW) radiation and its interactions with our planet has proven critical for advancing the understanding of the Earth–atmosphere system. Here, the author shares an accessible and high-level perspective on recent progress, surprises encountered, and promising future research directionsa. A brief context for the study of SW radiation is provided, after which three specific aspects are focused upon that the author considers particularly important. First, the significance of three-dimensional(3D) SW radiative effects is highlighted via impacts on surface downward SW radiation in complex cloud fields. Crucially, it is shown that probability distributions of surface radiation can only be reliably simulated when accounting for 3D effects, which has implications for various applications and next-generation atmospheric modeling. Second, the significance of the often overlooked diurnal cycle in global top-of-atmosphere upward SW radiation is underscored by quantifying the controlling properties and processes. Opportunities for improved future satellite observations of the global diurnal cycle are noted. Third, the wealth of information provided by the spectral dimension of SW radiation is demonstrated through the extraction and attribution of SW spectral signatures. It is argued that further exploration of the spectral dimension, aided by the recently launched and upcoming suite of spectrally resolved SW satellite observations, promises a new era of SW radiation research.展开更多
The radiative heat flux of the plume from reusable rockets is a critical parameter during the launch and return processes.This paper proposes a method for calculating radiative heat flux with higher accuracy than prev...The radiative heat flux of the plume from reusable rockets is a critical parameter during the launch and return processes.This paper proposes a method for calculating radiative heat flux with higher accuracy than previously reported for a recoverable nine-engine liquid-propellant rocket.Based on the Radiative Transfer Equation(RTE),this study employs the discrete transfer method to solve the transient RTE problem using physical properties to describe the problem while avoiding the need to directly solve mathematical equations.The proposed method can effectively determine the radiative heat flux of the flow field and is applicable to problems involving various geometries.Calculations reveal that during the ascent phase of the rocket,the radiative heat flux at the base of the vehicle reaches its maximum in the initial stages of the lift-off,reaching a maximum of~50 kW/m^(2),which is 2.24 times the maximum value during the return phase.During the deceleration stage of re-entry into the atmosphere,the maximum radiative heat flux recorded on the sidewall of the rocket is 29.1 kW/m^(2);the maximum heat flux on the bottom surface is approximately 22.3 kW/m^(2),accounting for 76.6%of that on the rocket's sidewall.This provides a basis for the thermal protection design of the rocket's bottom and walls as well as for the thermal management of cryogenic propellant tanks.Future research will involve ground engine testing and flight experiments to further validate the proposed model.展开更多
Radiative cooling systems(RCSs)possess the distinctive capability to dissipate heat energy via solar and thermal radiation,making them suitable for thermal regulation and energy conservation applications,essential for...Radiative cooling systems(RCSs)possess the distinctive capability to dissipate heat energy via solar and thermal radiation,making them suitable for thermal regulation and energy conservation applications,essential for mitigating the energy crisis.A comprehensive review connecting the advancements in engineered radiative cooling systems(ERCSs),encompassing material and structural design as well as thermal and energy-related applications,is currently absent.Herein,this review begins with a concise summary of the essential concepts of ERCSs,followed by an introduction to engineered materials and structures,containing nature-inspired designs,chromatic materials,meta-structural configurations,and multilayered constructions.It subsequently encapsulates the primary applications,including thermal-regulating textiles and energy-saving devices.Next,it highlights the challenges of ERCSs,including maximized thermoregulatory effects,environmental adaptability,scalability and sustainability,and interdisciplinary integration.It seeks to offer direction for forthcoming fundamental research and industrial advancement of radiative cooling systems in real-world applications.展开更多
By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,t...By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,the interior heating power would increase the working temperature and fire risk,which would suppress their above-ambient heat dissipation capabilities and passive water cycle properties.In this work,we introduced a REC design based on an all-in-one photonic hydrogel for above-ambient heat dissipation and flame retardancy.Unlike conventional design RC film for heat dissipation with limited cooling power and fire risk,REC hydrogel can greatly improve the heat dissipation performance in the daytime with a high workload,indicating a 12.0℃lower temperature than the RC film under the same conditions in the outdoor experiment.In the nighttime with a low workload,RC-assisted adsorption can improve atmospheric water harvesting to ensure EC in the daytime.In addition,our REC hydrogel significantly enhanced flame retardancy by absorbing heat without a corresponding temperature rise,thus mitigating fire risks.Thus,our design shows a promising solution for the thermal management of outdoor devices,delivering outstanding performance in both heat dissipation and flame retardancy.展开更多
Methods allowing passive daytime radiative cooling(PDRC)to be carried out in an energy-efficient and scalable way are potentially important for various disciplines.Here,we report a sustainable strategy for scalable-de...Methods allowing passive daytime radiative cooling(PDRC)to be carried out in an energy-efficient and scalable way are potentially important for various disciplines.Here,we report a sustainable strategy for scalable-designed and color-regulating PDRC coating based on high-crystallinity photonic metamaterial(crystallinity:71.5%;enhanced assembly efficiency:72%),that is derived from the as-prepared 55 wt%solid content poly(methyl methacrylate-butyl acrylate-methacrylic acid)P(MMA-BA-MAA)monodispersed latexes(approaching theoretical limit:59 wt%).Robust meter-scale PDRC coatings are constructed by various industrial modes onto diverse surfaces,addressing bottlenecks like dull appearance,high cost,low efficiency,and hard construction.Notably,the solar reflectance,long-wave infrared emittance,and calculated theoretical cooling power of the designed PDRC coating,respectively,reach~0.94,~0.97,and~95.5 W m^(-2)under solar radiation,which can achieve an average 5.3℃ sub-ambient daytime temperature drop in the summer in Nanjing.The cooling performance,scale preparation,and cost-effectiveness of the PDRC coating have extended into leading position compared with those of state-of-the-art designs.This work provides promising route to reduce carbon emissions and energy consumption for global sustainability.展开更多
Radiative cooling passively emits heat to outer space without energy input,offering promise for energy-efficient thermal management.It is an important solution to promote the low-carbon environmental protection strate...Radiative cooling passively emits heat to outer space without energy input,offering promise for energy-efficient thermal management.It is an important solution to promote the low-carbon environmental protection strategy.With the continuous development of radiative cooling technologies,the material selection,preparation process,structural design,and applica-tion fields have also made more diverse progress.Therefore,this review aims to systematically introduce the fundamental concepts and underlying principles of radiative cooling.A summary of the commonly used materials for radiative cooling is provided.In addition,the advanced fabrication processes and structural designs of radiative cooling materials are further explored and discussed.Subsequently,the unique functions of radiative cooling materials are highlighted to enhance their applicability and usefulness across various fields.An overview of combining radiative cooling materials with different fields is also provided.In reality,these applications hold the potential to improve thermal management across a range of fields.Finally,it summarizes the shortcomings and great potential of radiative cooling materials in various fields.It also looks forward to the future,aiming to promote the progress and widespread adoption of radiative cooling technologies.展开更多
Given that Xinjiang Uygur Autonomous Region of China possesses exceptionally abundant solar radiation resources that can be harnessed to develop clean energy,accurately characterizing their spatiotemporal distribution...Given that Xinjiang Uygur Autonomous Region of China possesses exceptionally abundant solar radiation resources that can be harnessed to develop clean energy,accurately characterizing their spatiotemporal distribution is crucial.This study investigated the applicability of the Clouds and the Earth's Radiant Energy System(CERES)Single Scanner Footprint TOA/Surface Fluxes and Clouds(SSF)product downward surface shortwave radiation dataset(DSSRCER)under clear-sky conditions in Xinjiang.By integrating multi-source data and utilizing techniques like multivariate fitting and model simulation,we established a two-layer aerosol model and developed a clear-sky downward surface shortwave radiation(DSSR)retrieval model specific to Xinjiang using the Santa Barbara Discrete Atmospheric Radiative Transfer(SBDART)model.We further explored the spatiotemporal distribution characteristics of DSSR under clear-sky conditions in Xinjiang from 2017 to 2019 based on the localized DSSR retrieval model.Our findings revealed a significant discrepancy in DSSRCER under clear-sky conditions at the Xiaotang station in Xinjiang.By comparing,screening,and correcting core input parameters while incorporating the two-layer aerosol model,we achieved a more accurate SBDART simulated DSSR(DSSRSBD)compared to DSSRCER.The annual mean DSSR exhibited a distinct distribution pattern with high values in mountainous regions such as the Altay Mountains,Kunlun Mountains,and Tianshan Mountains and significantly lower values in adjacent lowland areas,including the Tarim River Basin and Junggar Basin.In the four typical administrative regions in northern Xinjiang,the annual mean DSSR(ranging from 551.60 to 586.09 W/m^(2))was lower than that in the five typical administrative regions in southern Xinjiang(ranging from 522.10 to 623.62 W/m^(2)).These spatial variations stem from a complex interplay of factors,including latitude,altitude,solar altitude angle,and sunshine duration.The variations in seasonal average DSSR aligned closely with variations in the solar altitude angle,with summer(774.76 W/m^(2))exhibiting the highest values,followed by spring(684.86 W/m^(2)),autumn(544.76 W/m^(2)),and winter(422.74 W/m^(2)).The monthly average DSSR showed a unimodal distribution,peaking in June(792.94 W/m^(2))and reaching its lowest level in December(363.06 W/m^(2)).Overall,our study findings enhance the current understanding of the spatiotemporal distribution characteristics of DSSR in Xinjiang and provide certain references for the management of clean energy development in this region.展开更多
The radiative Euler equations is a typical model describing the motion of astrophysical flows.For its mathematical studies,it is now well-understood that the radiation effect can indeed induce some dissipative mechani...The radiative Euler equations is a typical model describing the motion of astrophysical flows.For its mathematical studies,it is now well-understood that the radiation effect can indeed induce some dissipative mechanism,which can guarantee the global regularity of smooth solutions to the radiative Euler equations for small initial data.Thus a problem of interest is to see to what extent does the viscosity and/or thermal conductivity influence the global regularity of smooth solutions to the one-dimensional radiative Euler equations for large initial data.For results in this direction,it is shown in[30]that,for a class of state equations,even if a special class of thermal conductivity is further added to the radiative Euler equations,its smooth solutions will still blow up in finite time for large initial data.The main purpose of this paper focuses on the case when both viscosity and thermal conductivity are considered.We first show that,for the state equations and the heat conductivity considered in[30],if the viscosity is further taken into account,the corresponding radiative Navier-Stokes equations does admit a unique global smooth solution for any large initial data provided that the viscosity is a smooth function of the density satisfying certain growth conditions as the density tends to zero and infinity.Moreover,we also show that similar result still holds for the case when the thermodynamics variables satisfy the state equations for ideal polytropic gases,the heat conductivity takes the form studied in[30],and the viscosity is assumed to satisfy the same conditions imposed in the first result.展开更多
Near-field thermal radiation has received increased attention due to the performance of efficient energy conversion.In this study,the vacuum gap distance between two objects,separated by 1μm polystyrene particles,is ...Near-field thermal radiation has received increased attention due to the performance of efficient energy conversion.In this study,the vacuum gap distance between two objects,separated by 1μm polystyrene particles,is investigated.The entire experimental device is installed in a highly vacuumed environment to ensure that the radiative heat flux dominates the main mode of heat transfer.Compared with the measurement of near-field thermal radiation of flat glasses,it is found that coating SiC film on the hot side of optical glass can reduce heat transfer.However,through theoretical analysis,it is shown that there is an optimal thickness of SiC film of around 1μm.In addition,the experimental data and theoretical analysis results are consistent.The experiment demonstrates that the regulation of radiative heat flux can be achieved by coating.As the thickness of SiC film on the hot side increases,the radiative heat flux decreases.展开更多
Rapid population growth in recent decades has intensified both the global energy crisis and the challenges posed by climate change,including global warming.Currently,the increased frequency of extreme weather events a...Rapid population growth in recent decades has intensified both the global energy crisis and the challenges posed by climate change,including global warming.Currently,the increased frequency of extreme weather events and large fluctuations in ambient temperature disrupt thermal comfort and negatively impact health,driving a growing dependence on cooling and heating energy sources.Consequently,efficient thermal management has become a central focus of energy research.Traditional thermal management systems consume substantial energy,further contributing to greenhouse gas emissions.In contrast,emergent radiant thermal management technologies that rely on renewable energy have been proposed as sustainable alternatives.However,achieving year-round thermal management without additional energy input remains a formidable challenge.Recently,dynamic radiative thermal management technologies have emerged as the most promising solution,offering the potential for energy-efficient adaptation across seasonal variations.This review systematically presents recent advancements in dynamic radiative thermal management,covering fundamental principles,switching mechanisms,primary materials,and application areas.Additionally,the key challenges hindering the broader adoption of dynamic radiative thermal management technologies are discussed.By highlighting their transformative potential,this review provides insights into the design and industrial scalability of these innovations,with the ultimate aim of promoting renewable energy integration in thermal management applications.展开更多
All-season thermal management with zero energy consumption and emissions is more crucial to global decarbonization over traditional energy-intensive cooling/heating systems.However,the static single thermal management...All-season thermal management with zero energy consumption and emissions is more crucial to global decarbonization over traditional energy-intensive cooling/heating systems.However,the static single thermal management for cooling or heating fails to self-regulate the temperature in dynamic seasonal temperature condition.Herein,inspired by the dual-temperature regulation function of the fur color changes on the backs and abdomens of penguins,a smart thermal management composite hydrogel(PNA@H-PM Gel)system was subtly created though an"on-demand"dual-layer structure design strategy.The PNA@H-PM Gel system features synchronous solar and thermal radiation modulation as well as tunable phase transition temperatures to meet the variable seasonal thermal requirements and energy-saving demands via self-adaptive radiative cooling and solar heating regulation.Furthermore,this system demonstrates superb modulations of both the solar reflectance(ΔR=0.74)and thermal emissivity(ΔE=0.52)in response to ambient temperature changes,highlighting efficient temperature regulation with average radiative cooling and solar heating effects of 9.6℃in summer and 6.1℃in winter,respectively.Moreover,compared to standard building baselines,the PNA@H-PM Gel presents a more substantial energy-saving cooling/heating potentials for energy-efficient buildings across various regions and climates.This novel solution,inspired by penguins in the real world,will offer a fresh approach for producing intelligent,energy-saving thermal management materials,and serve for temperature regulation under dynamic climate conditions and even throughout all seasons.展开更多
The continuous rise in turbine inlet temperatures in aero-engines has intensified the need for improved thermal insulation in thermal barrier coatings(TBCs).Traditionally,reducing the thermal conductivity of TBCs has ...The continuous rise in turbine inlet temperatures in aero-engines has intensified the need for improved thermal insulation in thermal barrier coatings(TBCs).Traditionally,reducing the thermal conductivity of TBCs has been the primary strategy to enhance their thermal insulation.Columnar TBCs are generally deemed to have higher thermal conductivity and inferior thermal insulation compared to lamellar TBCs.However,in this study,we demonstrate that under ultra-high temperature conditions(>1300℃),columnar TBCs exhibit superior radiative cooling capabilities due to their higher emissivity in the near-infrared region.This enhanced radiative heat dissipation effectively offsets the limitations of their high thermal conductivity.A novel"blackbody effect"hypothesis is proposed to elucidate this behavior.Finite element simulations quantitatively substantiate this hypothesis,showing strong agreement with experimental observations.These findings offer a groundbreaking perspective:columnar coatings,despite higher thermal conductivity,can narrow the thermal insulation gap with lamellar coatings at ultra-high temperatures through enhanced radiation cooling capabilities.This work provides a new structural strategy for optimizing emissivity and broadens the design framework for next-generation TBCs.展开更多
Accurate satellite data assimilation under all-sky conditions requires enhanced parameterization of scattering properties for frozen hydrometeors in clouds.This study aims to develop a nonspherical scattering look-up ...Accurate satellite data assimilation under all-sky conditions requires enhanced parameterization of scattering properties for frozen hydrometeors in clouds.This study aims to develop a nonspherical scattering look-up table that contains the optical properties of five hydrometeor types—rain,cloud water,cloud ice,graupel,and snow—for the Advanced Radiative Transfer Modeling System(ARMS)at frequencies below 220 GHz.The discrete dipole approximation(DDA)method is employed to compute the single-scattering properties of solid cloud particles,modeling these particles as aggregated roughened bullet rosettes.The bulk optical properties of the cloud layer are derived by integrating the singlescattering properties with a modified Gamma size distribution,specifically for distributions with 18 effective radii.The bulk phase function is then projected onto a series of generalized spherical functions,applying the delta-M method for truncation.The results indicate that simulations using the newly developed nonspherical scattering look-up table exhibit significant consistency with observations under deep convection conditions.In contrast,assuming spherical solid cloud particles leads to excessive scattering at mid-frequency channels and insufficient scattering at high-frequency channels.This improvement in radiative transfer simulation accuracy for cloudy conditions will better support the assimilation of allsky microwave observations into numerical weather prediction models.·Frozen cloud particles were modeled as aggregates of bullet rosettes and the optical properties at microwave range were computed by DDA.·A complete process and technical details for constructing a look-up table of ARMS are provided.·The ARMS simulations generally show agreement with observations of MWTS and MWHS under typhoon conditions using the new look-up table.展开更多
Hygroscopic hydrogel is a promising evaporativecooling material for high-power passive daytime cooling with water self-regeneration.However,undesired solar and environmental heating makes it a challenge to maintain su...Hygroscopic hydrogel is a promising evaporativecooling material for high-power passive daytime cooling with water self-regeneration.However,undesired solar and environmental heating makes it a challenge to maintain sub-ambient daytime cooling.While different strategies have been developed to mitigate heat gains,they inevitably sacrifice the evaporation and water regeneration due to highly coupled thermal and vapor transport.Here,an anisotropic synergistically performed insulation-radiation-evaporation(ASPIRE)cooler is developed by leveraging a dual-alignment structure both internal and external to the hydrogel for coordinated thermal and water transport.The ASPIRE cooler achieves an impressive average sub-ambient cooling temperature of~8.2℃ and a remarkable peak cooling power of 311 W m^(-2)under direct sunlight.Further examining the cooling mechanism reveals that the ASPIRE cooler reduces the solar and environmental heat gains without comprising the evaporation.Moreover,self-sustained multi-day cooling is possible with water self-regeneration at night under both clear and cloudy days.The synergistic design provides new insights toward high-power,sustainable,and all-weather passive cooling applications.展开更多
Radiative cooling is an environmentally friendly,passive cooling technology that operates without energy consumption.Current research primarily focuses on optimizing the optical properties of radiative cooling films t...Radiative cooling is an environmentally friendly,passive cooling technology that operates without energy consumption.Current research primarily focuses on optimizing the optical properties of radiative cooling films to enhance their cooling performance.In practical applications,thermal contact between the radiative cooling film and the object significantly influences the ultimate cooling performance.However,achieving optimal thermal contact has received limited attention.In this study,we propose and experimentally demonstrate a high-power,flexible,and magnetically attachable and detachable radiative cooling film.This film consists of polymer metasurface structures on a flexible magnetic layer.The monolithic design allows for convenient attachment to and detachment from steel or iron surfaces,ensuring optimal thermal contact with minimal thermal resistance and uniform temperature distribution.Our magnetic radiative cooling film exhibits superior cooling performance compared to non-magnetic alternatives.It can reduce the temperature of stainless-steel plates under sunlight by 15.2℃,which is 3.6℃ more than that achieved by non-magnetic radiative cooling films.The radiative cooling power can reach 259W·m^(-2) at a working temperature of 70℃.Unlike other commonly used attachment methods,such as thermal grease or one-off tape,our approach allows for detachment and reusability of the cooling film according to practical needs.This method offers great simplicity,flexibility,and cost-effectiveness,making it promising for broad applications,particularly on non-horizontal irregular surfaces previously considered challenging.展开更多
Radiative cooling fabric creates a thermally comfortable environment without energy input,providing a sustainable approach to personal thermal management.However,most currently reported fabrics mainly focus on outdoor...Radiative cooling fabric creates a thermally comfortable environment without energy input,providing a sustainable approach to personal thermal management.However,most currently reported fabrics mainly focus on outdoor cooling,ignoring to achieve simultaneous cooling both indoors and outdoors,thereby weakening the overall cooling performance.Herein,a full-scale structure fabric with selective emission properties is constructed for simultaneous indoor and outdoor cooling.The fabric achieves 94%reflectance performance in the sunlight band(0.3–2.5μm)and 6%in the mid-infrared band(2.5–25μm),effectively minimizing heat absorption and radiation release obstruction.It also demonstrates 81%radiative emission performance in the atmospheric window band(8–13μm)and 25%radiative transmission performance in the mid-infrared band(2.5–25μm),providing 60 and 26 W m−2 net cooling power outdoors and indoors.In practical applications,the fabric achieves excellent indoor and outdoor human cooling,with temperatures 1.4–5.5℃ lower than typical polydimethylsiloxane film.This work proposes a novel design for the advanced radiative cooling fabric,offering significant potential to realize sustainable personal thermal management.展开更多
The advancement of sophisticated smart windows exhibiting superior thermoregulation capabilities in both solar spectrum and long-wave infrared range maintains a prominent objective for researchers in this field.In thi...The advancement of sophisticated smart windows exhibiting superior thermoregulation capabilities in both solar spectrum and long-wave infrared range maintains a prominent objective for researchers in this field.In this study,a Janus window is proposed and prepared based on polymer-stabilized liquid-crystal films/thermochromic materials.It can achieve switchable front long-wave infrared emissivity(ε_(Front))and solar modulation ability(ΔT_(sol))through dynamic flipping,making it suitable for different seasonal energy-saving requirements.Outdoor experiments show that under daytime illumination,the indoor temperature decreases by 8℃,and the nighttime temperature drops by 5℃.MATLAB simulation calculations indicate that the daytime cooling power is 93 W m^(-2),while the nighttime cooling power reaches 142 W m^(-2).Interestingly,by modifying the conductive layer,it can effectively shield electromagnetic radiation(within the X-band frequency range(8.2-12.4)GHz).Energy simulation reveals the substantial superiority of this device in energy savings compared with single-layer polymer-stabilized liquid crystal,poly(N-isopropyl acrylamide),and normal glass when applied in different climate zones.This research presents a compelling opportunity for the development of sophisticated smart windows characterized by exceptional thermoregulation capabilities.展开更多
We consider the diffusion asymptotics of a coupled model arising in radiative transfer in a unit ball inℝ3 with one-speed velocity.The model consists of a steady kinetic equation satisfied by the specific intensity of...We consider the diffusion asymptotics of a coupled model arising in radiative transfer in a unit ball inℝ3 with one-speed velocity.The model consists of a steady kinetic equation satisfied by the specific intensity of radiation coupled with a nonhomogeneous elliptic equation satisfied by the material temperature.For the O(ϵ)boundary data of the intensity of the radiation and the suitable small boundary data of the temperature,we prove the existence,uniqueness and the nonequilibrium diffusion limit of solutions to the boundary value problem for the coupled model.展开更多
基金supported by the Taishan Scholars of Shandong Province(tsqn202408151)the National Natural Science Foundation of China(Grant Nos.52476067,52306078,and 52576053).
文摘As an emerging thermal management strategy,dynamic radiative cooling(DRC)technology enables dynamic modulation of spectral radiation properties under varying environmental conditions through the directional design of material spectral characteristics.However,a comprehensive review of the basic physical mechanisms of radiative heat transfer in DRC materials and various design principles involved in dynamic radiative thermal regulation is still lacking.This review systematically summarizes recent advances in this field,spanning from fundamental physical principles to intrinsic molecular and electronic mechanisms,and further to representative material systems and multi-band regulation strategies,highlighting the interdisciplinary research achievements and technological innovations.This work outlines the core mechanisms governing the regulation of different spectral bands during radiative heat transfer processes.Then,the main categories of DRC materials are systematically reviewed,including actively responsive structures,passively responsive structures,and multi-stimuli-responsive materials.Furthermore,the challenges faced by current DRC technology and future development trends are summarized and discussed,providing valuable reference and guidance for further research in this field.Although DRC technologies still face significant challenges in material stability,manufacturing processes,and system integration,the continuous advances in related areas and multifunctional materials are expected to broaden the application prospects of DRC in the future.
基金financial support from the National Natural Science Foundation of China(Grant No.52273067,52233006)the Fundamental Research Funds for the Central Universities(Grant No.2232023A-03)+3 种基金the Shuguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(Grant No.23SG29)the Natural Science Foundation of Shanghai(Grant No.24ZR1402400)the Shanghai Scientific and Technological Innovation Project(Grant No.24520713000)Innovation Program of Shanghai Municipal Education Commission(Grant No.2021-01-07-00-03-E00108).
文摘Radiative cooling textiles with spectrally selective surfaces offer a promising energy-efficient approach for sub-ambient cooling of outdoor objects and individuals.However,the spectrally selective mid-infrared emission of these textiles significantly hinders their efficient radiative heat exchange with self-heated objects,thereby posing a significant challenge to their versatile cooling applicability.Herein,we present a bicomponent blow spinning strategy for the production of scalable,ultra-flexible,and healable textiles featuring a tailored dual gradient in both chemical composition and fiber diameter.The gradient in the fiber diameter of this textile introduces a hierarchically porous structure across the sunlight incident area,thereby achieving a competitive solar reflectivity of 98.7%on its outer surface.Additionally,the gradient in the chemical composition of this textile contributes to the formation of Janus infrared-absorbing surfaces:The outer surface demonstrates a high mid-infrared emission,whereas the inner surface shows a broad infrared absorptivity,facilitating radiative heat exchange with underlying self-heated objects.Consequently,this textile demonstrates multi-scenario radiative cooling capabilities,enabling versatile outdoor cooling for unheated objects by 7.8℃ and self-heated objects by 13.6℃,compared to commercial sunshade fabrics.
基金the NOAA Atmospheric Science for Renewable Energy (ASRE) programthe Earth Venture Continuity 1 (EVC-1) Libera project under NASA Contract 80LARC20D0006the NOAA cooperative agreement with CIRES,NA22OAR4320151。
文摘The study of shortwave(SW) radiation and its interactions with our planet has proven critical for advancing the understanding of the Earth–atmosphere system. Here, the author shares an accessible and high-level perspective on recent progress, surprises encountered, and promising future research directionsa. A brief context for the study of SW radiation is provided, after which three specific aspects are focused upon that the author considers particularly important. First, the significance of three-dimensional(3D) SW radiative effects is highlighted via impacts on surface downward SW radiation in complex cloud fields. Crucially, it is shown that probability distributions of surface radiation can only be reliably simulated when accounting for 3D effects, which has implications for various applications and next-generation atmospheric modeling. Second, the significance of the often overlooked diurnal cycle in global top-of-atmosphere upward SW radiation is underscored by quantifying the controlling properties and processes. Opportunities for improved future satellite observations of the global diurnal cycle are noted. Third, the wealth of information provided by the spectral dimension of SW radiation is demonstrated through the extraction and attribution of SW spectral signatures. It is argued that further exploration of the spectral dimension, aided by the recently launched and upcoming suite of spectrally resolved SW satellite observations, promises a new era of SW radiation research.
文摘The radiative heat flux of the plume from reusable rockets is a critical parameter during the launch and return processes.This paper proposes a method for calculating radiative heat flux with higher accuracy than previously reported for a recoverable nine-engine liquid-propellant rocket.Based on the Radiative Transfer Equation(RTE),this study employs the discrete transfer method to solve the transient RTE problem using physical properties to describe the problem while avoiding the need to directly solve mathematical equations.The proposed method can effectively determine the radiative heat flux of the flow field and is applicable to problems involving various geometries.Calculations reveal that during the ascent phase of the rocket,the radiative heat flux at the base of the vehicle reaches its maximum in the initial stages of the lift-off,reaching a maximum of~50 kW/m^(2),which is 2.24 times the maximum value during the return phase.During the deceleration stage of re-entry into the atmosphere,the maximum radiative heat flux recorded on the sidewall of the rocket is 29.1 kW/m^(2);the maximum heat flux on the bottom surface is approximately 22.3 kW/m^(2),accounting for 76.6%of that on the rocket's sidewall.This provides a basis for the thermal protection design of the rocket's bottom and walls as well as for the thermal management of cryogenic propellant tanks.Future research will involve ground engine testing and flight experiments to further validate the proposed model.
基金support from the Contract Research(“Development of Breathable Fabrics with Nano-Electrospun Membrane”,CityU ref.:9231419“Research and application of antibacterial and healing-promoting smart nanofiber dressing for children’s burn wounds”,CityU ref:PJ9240111)+1 种基金the National Natural Science Foundation of China(“Study of Multi-Responsive Shape Memory Polyurethane Nanocomposites Inspired by Natural Fibers”,Grant No.51673162)Startup Grant of CityU(“Laboratory of Wearable Materials for Healthcare”,Grant No.9380116).
文摘Radiative cooling systems(RCSs)possess the distinctive capability to dissipate heat energy via solar and thermal radiation,making them suitable for thermal regulation and energy conservation applications,essential for mitigating the energy crisis.A comprehensive review connecting the advancements in engineered radiative cooling systems(ERCSs),encompassing material and structural design as well as thermal and energy-related applications,is currently absent.Herein,this review begins with a concise summary of the essential concepts of ERCSs,followed by an introduction to engineered materials and structures,containing nature-inspired designs,chromatic materials,meta-structural configurations,and multilayered constructions.It subsequently encapsulates the primary applications,including thermal-regulating textiles and energy-saving devices.Next,it highlights the challenges of ERCSs,including maximized thermoregulatory effects,environmental adaptability,scalability and sustainability,and interdisciplinary integration.It seeks to offer direction for forthcoming fundamental research and industrial advancement of radiative cooling systems in real-world applications.
基金financially supported by the Science and Technology Innovation Program of Hunan Province(2024RC3003)the Central South University Innovation-Driven Research Programme(2023CXQD012)the Initiative for Sustainable Energy for its financial support。
文摘By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,the interior heating power would increase the working temperature and fire risk,which would suppress their above-ambient heat dissipation capabilities and passive water cycle properties.In this work,we introduced a REC design based on an all-in-one photonic hydrogel for above-ambient heat dissipation and flame retardancy.Unlike conventional design RC film for heat dissipation with limited cooling power and fire risk,REC hydrogel can greatly improve the heat dissipation performance in the daytime with a high workload,indicating a 12.0℃lower temperature than the RC film under the same conditions in the outdoor experiment.In the nighttime with a low workload,RC-assisted adsorption can improve atmospheric water harvesting to ensure EC in the daytime.In addition,our REC hydrogel significantly enhanced flame retardancy by absorbing heat without a corresponding temperature rise,thus mitigating fire risks.Thus,our design shows a promising solution for the thermal management of outdoor devices,delivering outstanding performance in both heat dissipation and flame retardancy.
基金support of the National Natural Science Foundation of China(grant 22508184 to X.Q.Y.,grant 21736006 to S.C.,and grant 22278225 to S.C.)supported by the Natural Funding Program of Jiangsu Province(grant BK20250610 to X.Q.Y.).
文摘Methods allowing passive daytime radiative cooling(PDRC)to be carried out in an energy-efficient and scalable way are potentially important for various disciplines.Here,we report a sustainable strategy for scalable-designed and color-regulating PDRC coating based on high-crystallinity photonic metamaterial(crystallinity:71.5%;enhanced assembly efficiency:72%),that is derived from the as-prepared 55 wt%solid content poly(methyl methacrylate-butyl acrylate-methacrylic acid)P(MMA-BA-MAA)monodispersed latexes(approaching theoretical limit:59 wt%).Robust meter-scale PDRC coatings are constructed by various industrial modes onto diverse surfaces,addressing bottlenecks like dull appearance,high cost,low efficiency,and hard construction.Notably,the solar reflectance,long-wave infrared emittance,and calculated theoretical cooling power of the designed PDRC coating,respectively,reach~0.94,~0.97,and~95.5 W m^(-2)under solar radiation,which can achieve an average 5.3℃ sub-ambient daytime temperature drop in the summer in Nanjing.The cooling performance,scale preparation,and cost-effectiveness of the PDRC coating have extended into leading position compared with those of state-of-the-art designs.This work provides promising route to reduce carbon emissions and energy consumption for global sustainability.
基金National Natural Science Foundation of China Excellent Youth Fund(No.52222509)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52021003)+3 种基金National Key Research and Development Program of China(No.2018YFA0703300)National Natural Science Foundation of China(No.52105298)Science and Technology Development Program of Jilin Province(No.SKL202402005)"Fundamental Research Funds for the Central Universities".
文摘Radiative cooling passively emits heat to outer space without energy input,offering promise for energy-efficient thermal management.It is an important solution to promote the low-carbon environmental protection strategy.With the continuous development of radiative cooling technologies,the material selection,preparation process,structural design,and applica-tion fields have also made more diverse progress.Therefore,this review aims to systematically introduce the fundamental concepts and underlying principles of radiative cooling.A summary of the commonly used materials for radiative cooling is provided.In addition,the advanced fabrication processes and structural designs of radiative cooling materials are further explored and discussed.Subsequently,the unique functions of radiative cooling materials are highlighted to enhance their applicability and usefulness across various fields.An overview of combining radiative cooling materials with different fields is also provided.In reality,these applications hold the potential to improve thermal management across a range of fields.Finally,it summarizes the shortcomings and great potential of radiative cooling materials in various fields.It also looks forward to the future,aiming to promote the progress and widespread adoption of radiative cooling technologies.
基金supported by the Science and Technology Planning Program of Xinjiang,China(2022E01047)the Natural Science Basic Research Program of Shaanxi(2025JC-YBQN-404)+2 种基金the 2025 Shaanxi Special Research Project of Philosophy and Social Sciences(2025QN0573)the Scientific Research Program Funded by Education Department of Shaanxi Provincial Government(23JK0625)the National Natural Science Foundation of China(42030612)。
文摘Given that Xinjiang Uygur Autonomous Region of China possesses exceptionally abundant solar radiation resources that can be harnessed to develop clean energy,accurately characterizing their spatiotemporal distribution is crucial.This study investigated the applicability of the Clouds and the Earth's Radiant Energy System(CERES)Single Scanner Footprint TOA/Surface Fluxes and Clouds(SSF)product downward surface shortwave radiation dataset(DSSRCER)under clear-sky conditions in Xinjiang.By integrating multi-source data and utilizing techniques like multivariate fitting and model simulation,we established a two-layer aerosol model and developed a clear-sky downward surface shortwave radiation(DSSR)retrieval model specific to Xinjiang using the Santa Barbara Discrete Atmospheric Radiative Transfer(SBDART)model.We further explored the spatiotemporal distribution characteristics of DSSR under clear-sky conditions in Xinjiang from 2017 to 2019 based on the localized DSSR retrieval model.Our findings revealed a significant discrepancy in DSSRCER under clear-sky conditions at the Xiaotang station in Xinjiang.By comparing,screening,and correcting core input parameters while incorporating the two-layer aerosol model,we achieved a more accurate SBDART simulated DSSR(DSSRSBD)compared to DSSRCER.The annual mean DSSR exhibited a distinct distribution pattern with high values in mountainous regions such as the Altay Mountains,Kunlun Mountains,and Tianshan Mountains and significantly lower values in adjacent lowland areas,including the Tarim River Basin and Junggar Basin.In the four typical administrative regions in northern Xinjiang,the annual mean DSSR(ranging from 551.60 to 586.09 W/m^(2))was lower than that in the five typical administrative regions in southern Xinjiang(ranging from 522.10 to 623.62 W/m^(2)).These spatial variations stem from a complex interplay of factors,including latitude,altitude,solar altitude angle,and sunshine duration.The variations in seasonal average DSSR aligned closely with variations in the solar altitude angle,with summer(774.76 W/m^(2))exhibiting the highest values,followed by spring(684.86 W/m^(2)),autumn(544.76 W/m^(2)),and winter(422.74 W/m^(2)).The monthly average DSSR showed a unimodal distribution,peaking in June(792.94 W/m^(2))and reaching its lowest level in December(363.06 W/m^(2)).Overall,our study findings enhance the current understanding of the spatiotemporal distribution characteristics of DSSR in Xinjiang and provide certain references for the management of clean energy development in this region.
基金supported by the NSFC(12001495)supported by the NSFC(12221001,12371225)the Science and Technology Department of Hubei Province(2020DFH002)。
文摘The radiative Euler equations is a typical model describing the motion of astrophysical flows.For its mathematical studies,it is now well-understood that the radiation effect can indeed induce some dissipative mechanism,which can guarantee the global regularity of smooth solutions to the radiative Euler equations for small initial data.Thus a problem of interest is to see to what extent does the viscosity and/or thermal conductivity influence the global regularity of smooth solutions to the one-dimensional radiative Euler equations for large initial data.For results in this direction,it is shown in[30]that,for a class of state equations,even if a special class of thermal conductivity is further added to the radiative Euler equations,its smooth solutions will still blow up in finite time for large initial data.The main purpose of this paper focuses on the case when both viscosity and thermal conductivity are considered.We first show that,for the state equations and the heat conductivity considered in[30],if the viscosity is further taken into account,the corresponding radiative Navier-Stokes equations does admit a unique global smooth solution for any large initial data provided that the viscosity is a smooth function of the density satisfying certain growth conditions as the density tends to zero and infinity.Moreover,we also show that similar result still holds for the case when the thermodynamics variables satisfy the state equations for ideal polytropic gases,the heat conductivity takes the form studied in[30],and the viscosity is assumed to satisfy the same conditions imposed in the first result.
文摘Near-field thermal radiation has received increased attention due to the performance of efficient energy conversion.In this study,the vacuum gap distance between two objects,separated by 1μm polystyrene particles,is investigated.The entire experimental device is installed in a highly vacuumed environment to ensure that the radiative heat flux dominates the main mode of heat transfer.Compared with the measurement of near-field thermal radiation of flat glasses,it is found that coating SiC film on the hot side of optical glass can reduce heat transfer.However,through theoretical analysis,it is shown that there is an optimal thickness of SiC film of around 1μm.In addition,the experimental data and theoretical analysis results are consistent.The experiment demonstrates that the regulation of radiative heat flux can be achieved by coating.As the thickness of SiC film on the hot side increases,the radiative heat flux decreases.
基金the Institute of Biomass & Functional Materials of Shaanxi University of Science and Technology for funding this research workfinancially supported by the National Natural Science Foundation of China (2207081675, 22278257, 22308209)+1 种基金the Key R&D Program of Shaanxi Province (2024SF-YBXM-586)the Project of Innovation Capability Support Program in Shaanxi Province (2024ZC-KJXX-005)
文摘Rapid population growth in recent decades has intensified both the global energy crisis and the challenges posed by climate change,including global warming.Currently,the increased frequency of extreme weather events and large fluctuations in ambient temperature disrupt thermal comfort and negatively impact health,driving a growing dependence on cooling and heating energy sources.Consequently,efficient thermal management has become a central focus of energy research.Traditional thermal management systems consume substantial energy,further contributing to greenhouse gas emissions.In contrast,emergent radiant thermal management technologies that rely on renewable energy have been proposed as sustainable alternatives.However,achieving year-round thermal management without additional energy input remains a formidable challenge.Recently,dynamic radiative thermal management technologies have emerged as the most promising solution,offering the potential for energy-efficient adaptation across seasonal variations.This review systematically presents recent advancements in dynamic radiative thermal management,covering fundamental principles,switching mechanisms,primary materials,and application areas.Additionally,the key challenges hindering the broader adoption of dynamic radiative thermal management technologies are discussed.By highlighting their transformative potential,this review provides insights into the design and industrial scalability of these innovations,with the ultimate aim of promoting renewable energy integration in thermal management applications.
基金the funding and generous support of the National Natural Science Foundation of China(52103263,52271249)the Key Project of International Science&Technology Cooperation of Shaanxi Province(2023-GHZD-09)+5 种基金the Key Project of Science Foundation of Education Department of Shaanxi Province(22JY011)the Key Project of Scientific Research and Development of Shaanxi Province(2023GXLH-070)the Qinchuangyuan"Scientist+Engineer"Team of Shaanxi Province(2023KXJ-069)the Key Research and Development Program of Shaanxi(2023-YBGY-488)the Sci-tech Innovation Team of Shaanxi Province(2024RS-CXTD-46)the Key Research and Development Program of Shaanxi Province(2020ZDLGY13-11).
文摘All-season thermal management with zero energy consumption and emissions is more crucial to global decarbonization over traditional energy-intensive cooling/heating systems.However,the static single thermal management for cooling or heating fails to self-regulate the temperature in dynamic seasonal temperature condition.Herein,inspired by the dual-temperature regulation function of the fur color changes on the backs and abdomens of penguins,a smart thermal management composite hydrogel(PNA@H-PM Gel)system was subtly created though an"on-demand"dual-layer structure design strategy.The PNA@H-PM Gel system features synchronous solar and thermal radiation modulation as well as tunable phase transition temperatures to meet the variable seasonal thermal requirements and energy-saving demands via self-adaptive radiative cooling and solar heating regulation.Furthermore,this system demonstrates superb modulations of both the solar reflectance(ΔR=0.74)and thermal emissivity(ΔE=0.52)in response to ambient temperature changes,highlighting efficient temperature regulation with average radiative cooling and solar heating effects of 9.6℃in summer and 6.1℃in winter,respectively.Moreover,compared to standard building baselines,the PNA@H-PM Gel presents a more substantial energy-saving cooling/heating potentials for energy-efficient buildings across various regions and climates.This novel solution,inspired by penguins in the real world,will offer a fresh approach for producing intelligent,energy-saving thermal management materials,and serve for temperature regulation under dynamic climate conditions and even throughout all seasons.
基金financially supported by the National Key Research and Development Program of China(No.2022YFB3504902)the Natural Science Foundation of China(NSFC)(Nos.U21B2052 and 52102057)the Science Center for Gas Turbine Project(No.P2023-C-Ⅳ-002-001).
文摘The continuous rise in turbine inlet temperatures in aero-engines has intensified the need for improved thermal insulation in thermal barrier coatings(TBCs).Traditionally,reducing the thermal conductivity of TBCs has been the primary strategy to enhance their thermal insulation.Columnar TBCs are generally deemed to have higher thermal conductivity and inferior thermal insulation compared to lamellar TBCs.However,in this study,we demonstrate that under ultra-high temperature conditions(>1300℃),columnar TBCs exhibit superior radiative cooling capabilities due to their higher emissivity in the near-infrared region.This enhanced radiative heat dissipation effectively offsets the limitations of their high thermal conductivity.A novel"blackbody effect"hypothesis is proposed to elucidate this behavior.Finite element simulations quantitatively substantiate this hypothesis,showing strong agreement with experimental observations.These findings offer a groundbreaking perspective:columnar coatings,despite higher thermal conductivity,can narrow the thermal insulation gap with lamellar coatings at ultra-high temperatures through enhanced radiation cooling capabilities.This work provides a new structural strategy for optimizing emissivity and broadens the design framework for next-generation TBCs.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB3900400)the National Natural Science Foundation of China(Grant Nos.U2142212 and 42361074)。
文摘Accurate satellite data assimilation under all-sky conditions requires enhanced parameterization of scattering properties for frozen hydrometeors in clouds.This study aims to develop a nonspherical scattering look-up table that contains the optical properties of five hydrometeor types—rain,cloud water,cloud ice,graupel,and snow—for the Advanced Radiative Transfer Modeling System(ARMS)at frequencies below 220 GHz.The discrete dipole approximation(DDA)method is employed to compute the single-scattering properties of solid cloud particles,modeling these particles as aggregated roughened bullet rosettes.The bulk optical properties of the cloud layer are derived by integrating the singlescattering properties with a modified Gamma size distribution,specifically for distributions with 18 effective radii.The bulk phase function is then projected onto a series of generalized spherical functions,applying the delta-M method for truncation.The results indicate that simulations using the newly developed nonspherical scattering look-up table exhibit significant consistency with observations under deep convection conditions.In contrast,assuming spherical solid cloud particles leads to excessive scattering at mid-frequency channels and insufficient scattering at high-frequency channels.This improvement in radiative transfer simulation accuracy for cloudy conditions will better support the assimilation of allsky microwave observations into numerical weather prediction models.·Frozen cloud particles were modeled as aggregates of bullet rosettes and the optical properties at microwave range were computed by DDA.·A complete process and technical details for constructing a look-up table of ARMS are provided.·The ARMS simulations generally show agreement with observations of MWTS and MWHS under typhoon conditions using the new look-up table.
基金financially supported by the Young Scientists Fund of National Natural Science Foundation of China(Grant No.52303106)Research Grants Council of Hong Kong SAR(16200720)+3 种基金Environment and Conservation Fund of Hong Kong SAR(Project No.21/2022)Research Institute of Sports Science and Technology(Project No.P0043535)Research Institute of Advanced Manufacturing(Project No.P0046125)the start-up fund for new recruits of Poly U(Project No.P0038855 and P0038858)。
文摘Hygroscopic hydrogel is a promising evaporativecooling material for high-power passive daytime cooling with water self-regeneration.However,undesired solar and environmental heating makes it a challenge to maintain sub-ambient daytime cooling.While different strategies have been developed to mitigate heat gains,they inevitably sacrifice the evaporation and water regeneration due to highly coupled thermal and vapor transport.Here,an anisotropic synergistically performed insulation-radiation-evaporation(ASPIRE)cooler is developed by leveraging a dual-alignment structure both internal and external to the hydrogel for coordinated thermal and water transport.The ASPIRE cooler achieves an impressive average sub-ambient cooling temperature of~8.2℃ and a remarkable peak cooling power of 311 W m^(-2)under direct sunlight.Further examining the cooling mechanism reveals that the ASPIRE cooler reduces the solar and environmental heat gains without comprising the evaporation.Moreover,self-sustained multi-day cooling is possible with water self-regeneration at night under both clear and cloudy days.The synergistic design provides new insights toward high-power,sustainable,and all-weather passive cooling applications.
基金supported by the Australia Research Council through the Discovery Project scheme(DP190103186 and DP220100603)the Industrial Transformation Training Centres scheme(IC180100005)+5 种基金the Future Fellowship scheme(FT210100806)the Future Fellowship scheme(FT220100559)the Discovery Early Career Researcher Award scheme(DE230100383)the Shenzhen Science and Technology Program(GJHZ20240218113407015)the Natural Science Foundation of Shandong Province(ZR2021ME162)the Key Research and Development Program of Shandong Province,China(2022SFGC0501).
文摘Radiative cooling is an environmentally friendly,passive cooling technology that operates without energy consumption.Current research primarily focuses on optimizing the optical properties of radiative cooling films to enhance their cooling performance.In practical applications,thermal contact between the radiative cooling film and the object significantly influences the ultimate cooling performance.However,achieving optimal thermal contact has received limited attention.In this study,we propose and experimentally demonstrate a high-power,flexible,and magnetically attachable and detachable radiative cooling film.This film consists of polymer metasurface structures on a flexible magnetic layer.The monolithic design allows for convenient attachment to and detachment from steel or iron surfaces,ensuring optimal thermal contact with minimal thermal resistance and uniform temperature distribution.Our magnetic radiative cooling film exhibits superior cooling performance compared to non-magnetic alternatives.It can reduce the temperature of stainless-steel plates under sunlight by 15.2℃,which is 3.6℃ more than that achieved by non-magnetic radiative cooling films.The radiative cooling power can reach 259W·m^(-2) at a working temperature of 70℃.Unlike other commonly used attachment methods,such as thermal grease or one-off tape,our approach allows for detachment and reusability of the cooling film according to practical needs.This method offers great simplicity,flexibility,and cost-effectiveness,making it promising for broad applications,particularly on non-horizontal irregular surfaces previously considered challenging.
基金financially supported by Heilongjiang Postdoctoral Fund(Grant No.LBH-Z24057)Outstanding Master’s and Doctoral Thesis of Longjiang in the New Era(Grant No.LJYXL2023-076).
文摘Radiative cooling fabric creates a thermally comfortable environment without energy input,providing a sustainable approach to personal thermal management.However,most currently reported fabrics mainly focus on outdoor cooling,ignoring to achieve simultaneous cooling both indoors and outdoors,thereby weakening the overall cooling performance.Herein,a full-scale structure fabric with selective emission properties is constructed for simultaneous indoor and outdoor cooling.The fabric achieves 94%reflectance performance in the sunlight band(0.3–2.5μm)and 6%in the mid-infrared band(2.5–25μm),effectively minimizing heat absorption and radiation release obstruction.It also demonstrates 81%radiative emission performance in the atmospheric window band(8–13μm)and 25%radiative transmission performance in the mid-infrared band(2.5–25μm),providing 60 and 26 W m−2 net cooling power outdoors and indoors.In practical applications,the fabric achieves excellent indoor and outdoor human cooling,with temperatures 1.4–5.5℃ lower than typical polydimethylsiloxane film.This work proposes a novel design for the advanced radiative cooling fabric,offering significant potential to realize sustainable personal thermal management.
基金supported by the National Natural Science Foundation of China(52372279,52103071,52203322,52473289,52303220)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities in China,FRF-IDRY-GD22-001)。
文摘The advancement of sophisticated smart windows exhibiting superior thermoregulation capabilities in both solar spectrum and long-wave infrared range maintains a prominent objective for researchers in this field.In this study,a Janus window is proposed and prepared based on polymer-stabilized liquid-crystal films/thermochromic materials.It can achieve switchable front long-wave infrared emissivity(ε_(Front))and solar modulation ability(ΔT_(sol))through dynamic flipping,making it suitable for different seasonal energy-saving requirements.Outdoor experiments show that under daytime illumination,the indoor temperature decreases by 8℃,and the nighttime temperature drops by 5℃.MATLAB simulation calculations indicate that the daytime cooling power is 93 W m^(-2),while the nighttime cooling power reaches 142 W m^(-2).Interestingly,by modifying the conductive layer,it can effectively shield electromagnetic radiation(within the X-band frequency range(8.2-12.4)GHz).Energy simulation reveals the substantial superiority of this device in energy savings compared with single-layer polymer-stabilized liquid crystal,poly(N-isopropyl acrylamide),and normal glass when applied in different climate zones.This research presents a compelling opportunity for the development of sophisticated smart windows characterized by exceptional thermoregulation capabilities.
基金Zhang’s research was supported by the NSFC(12271423,12071044)the Fundamental Research Funds for the Central Universities(xzy012022005)the Shaanxi Fundamental Science Research Project for Mathematics and Physics(23JSY026).
文摘We consider the diffusion asymptotics of a coupled model arising in radiative transfer in a unit ball inℝ3 with one-speed velocity.The model consists of a steady kinetic equation satisfied by the specific intensity of radiation coupled with a nonhomogeneous elliptic equation satisfied by the material temperature.For the O(ϵ)boundary data of the intensity of the radiation and the suitable small boundary data of the temperature,we prove the existence,uniqueness and the nonequilibrium diffusion limit of solutions to the boundary value problem for the coupled model.
