Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical co...Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical conductivity,high solar absorptivity,and low infrared emissivity at the same time are rare in na-ture,which are highly anticipated and of great significance for highly efficient electric/solar heating.In this work,we demonstrate that Ti_(3)C_(2)T_(x) MXene with low IR emissivity(14.5%)fills the gap in the absence of the above materials,exhibiting a remarkable electric/solar heating performance.The saturated heating temperature of Ti_(3)C_(2)T_(x) film reaches a record-high value of 201°C at a low driving voltage of 1.5 V,and reaches 84.3°C under practical solar irradiation(750 W/m^(2))with a high solar to the thermal conversion efficiency of 75.3%,which is far superior to other reported materials.Meanwhile,the low IR emissivity endows Ti_(3)C_(2)T_(x) with a remarkable passive radiative heating capability of 7.0°C,ensuring zero-energy heating without electric/solar energy supply.The intrinsic characteristic of high electrical conductivity,high solar absorptivity,and low IR emissivity makes Ti_(3)C_(2)T_(x) unique existence in nature,which is highly promising for all-day and all-weather energy-saving heating.展开更多
Based on the 1%CO_(2) experiment of CMIP6,in response to increasing CO_(2),the summer-mean radiative heating(RH)over the global monsoon area(MA)generally features an increasing response in the mid-troposphere and a de...Based on the 1%CO_(2) experiment of CMIP6,in response to increasing CO_(2),the summer-mean radiative heating(RH)over the global monsoon area(MA)generally features an increasing response in the mid-troposphere and a decreasing response in the lower and upper troposphere.The pressure level of the maximum RH increase over the Asian MA is the highest and largest in range(500–775 hPa);the maximum increases over the North African,South American,and Australian MA are at 550–600 hPa;throughout the North American MA,the maximum heating increase is at 600 hPa;and the levels of the maximum over South Africa are 600 and 775 hPa.For most of the global MA,the maximum enhancement of RH is at 500,550,and 600 hPa.It is mainly led by the increase in cloud water at and above the maximum level and the decrease in cloud water below,which leads to similar changes in total cloud mass.Because of the longwave heating(cooling)effect at the cloud base(top),the RH enhancements peak at those levels.For the northeast part of the Asian MA and southeast part of the South African MA,RH enhancement peaks at 700 and 775 hPa,mainly attributable to the cloud water reduction below.The reduction leads to similar changes in total cloud.Due to the longwave cooling effect at the cloud top,the reduction contributes to the RH enhancement at the corresponding maximum levels.展开更多
Switchable radiative cooling/heating holds great promise for mitigating the global energy and environmental crisis.Here,we reported a cost-effective,high-strength Janus film through surface optical engineering waste p...Switchable radiative cooling/heating holds great promise for mitigating the global energy and environmental crisis.Here,we reported a cost-effective,high-strength Janus film through surface optical engineering waste paper with one side decorated by a hydrophobic polymeric cooling coating consisting of micro/nanopore/particle hierarchical structure and the other side coated with hydrophilic MXene nanosheets for heating.The cooling surface demonstrates high solar reflectivity(96.3%)and infrared emissivity(95.5%),resulting in daytime/nighttime sub-ambient radiative cooling of 6℃/8℃with the theoretical cooling power of 100.6 and 138.5Wm^(−2),respectively.The heating surface exhibits high solar absorptivity(83.7%)and low infrared emissivity(15.2%),resulting in excellent radiative heating capacity for vehicle charging pile(~6.2℃)and solar heating performance.Impressively,the mechanical strength of Janus film increased greatly by 563%compared with that of pristine waste paper,which is helpful for its practical applications in various scenarios for switchable radiative thermal management through mechanical flipping.Energy-saving simulation results reveal that significant total energy savings of up to 32.4MJm^(−2) can be achieved annually(corresponding to the 12.4%saving ratio),showing the immense importance of reducing carbon footprint and promoting carbon neutrality.展开更多
Maintaining thermal comfort within the human body is crucial for optimal health and overall well-being.By merely broadening the setpoint of indoor temperatures,we could significantly slash energy usage in building hea...Maintaining thermal comfort within the human body is crucial for optimal health and overall well-being.By merely broadening the setpoint of indoor temperatures,we could significantly slash energy usage in building heating,ventilation,and air-conditioning systems.In recent years,there has been a surge in advancements in personal thermal management(PTM),aiming to regulate heat and moisture transfer within our immediate surroundings,clothing,and skin.The advent of PTM is driven by the rapid development in nano/micro-materials and energy science and engineering.An emerging research area in PTM is personal radiative thermal management(PRTM),which demonstrates immense potential with its high radiative heat transfer efficiency and ease of regulation.However,it is less taken into account in traditional textiles,and there currently lies a gap in our knowledge and understanding of PRTM.In this review,we aim to present a thorough analysis of advanced textile materials and technologies for PRTM.Specifically,we will introduce and discuss the underlying radiation heat transfer mechanisms,fabrication methods of textiles,and various indoor/outdoor applications in light of their different regulation functionalities,including radiative cooling,radiative heating,and dual-mode thermoregulation.Furthermore,we will shine a light on the current hurdles,propose potential strategies,and delve into future technology trends for PRTM with an emphasis on functionalities and applications.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
Visible transparent yet low infrared-emissivity(ε)polymeric materials are highly anticipated in many applications,whereas the fabrication of which remains a formidable challenge.Herein,visible transparent,flexible,an...Visible transparent yet low infrared-emissivity(ε)polymeric materials are highly anticipated in many applications,whereas the fabrication of which remains a formidable challenge.Herein,visible transparent,flexible,and low-εpolymeric films were fabricated by nanocoating decoration of indium tin oxide(ITO)and MXene on polyethylene terephthalate(PET)film surface through magnetron sputtering and spray coating,respectively.The obtained PET-ITO@MXene(PET-IM)film exhibits lowεof 24.7%and high visible transmittance exceeding 50%,endowing it with excellent visible transparent infrared stealthy by reducing human skin radiation temperature from 32 to 20.8°C,and remarkable zero-energy passive radiative heating capability(5.7°C).Meanwhile,the transparent low-εPET-IM film has high solar absorptivity and electrical conductivity,enabling superior solar/electric to thermal conversion performance.Notably,the three heating modes of passive radiative and active solar/electric can be integrated together to cope with complex heating scenarios.These visible transparent low-εpolymeric films are highly promising in infrared stealth,building daylighting and thermal management,and personal precision heating.展开更多
The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the...The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the lower atmosphere over central China to be smaller than the fluxes over southern and northern China by generating more clouds. The existence of a larger quantity of clouds over central China reflects a greater amount of solar radiation back into space. The vertical gradients of upward shortwave radiative fluxes in the atmosphere below 8 km are greater than those above 8 km. The latitudinal-altitude distributions of downward longwave radiative fluxes show a slantwise decreasing trend from low latitudes to high latitudes that gradually weaken in the downward direction. The upward longwave radiative fluxes also weaken in the upward direction but with larger gradients. The maximum heating rates by solar radiation and cooling rates by longwave infrared radiation are located over 28 40°N at 7 8 km mean sea level (MSL), and they are larger than the rates in the northern and southern regions. The heating and cooling rates match well both vertically and geographically.展开更多
Convective heat transfer and radiative heat transfer are two essential heat transfer modes in the heating process of steel;it is important to understand the role of them during the heating process clearly.The effects ...Convective heat transfer and radiative heat transfer are two essential heat transfer modes in the heating process of steel;it is important to understand the role of them during the heating process clearly.The effects of the convective and radiative heat transfer during the heating process of a cast ingot in a tubular furnace have been studied by the designed natural and forced convection experiments and mathematical simulations.The heating time for the center of the ingot to reach the furnace temperature is decreased with the increase in furnace temperature.According to the experimental and simulation results,a model is proposed regarding the role of radiative and convective heat transfer in the heating process.At low temperature,the convective heat transfer plays a dominant role,while at high temperature,the influence of radiative heat transfer is larger.And a critical temperature exists between them.The forced convective heat transfer can enhance the influence of the convective heat transfer.The critical temperature can be shifted to higher temperatures.展开更多
Near-field radiative heat transfer(NFRHT)has the potential to exceed the blackbody limit by several orders of magnitude,offering significant opportunities for energy harvesting.In this study,we have examined the NFRHT...Near-field radiative heat transfer(NFRHT)has the potential to exceed the blackbody limit by several orders of magnitude,offering significant opportunities for energy harvesting.In this study,we have examined the NFRHT between two borophene sheets through the calculation of heat transfer coefficient(HTC).Due to the tunneling of evanescent waves,borophene sheet allows for enhanced heat flux and adjustable NFRHT by varying its electron density and electron relaxation time.Additionally,the near field coupling is further examined when the borophene is deposited on dielectric or lossy substrates.The maximum HTC is closely related to the real part of the dielectric substrate.As a case study,the HTCs on the lossy substrate of MoO_(3),ZnSe,and SiC are calculated for comparisons.Our results indicate that MoO_(3)is the optimal substrate to get the enhanced energy transfer coefficient.It results in a remarkable value of 1737 times higher than the blackbody limit owing to the enhanced photon tunneling probability.Thus,our study reveals the effect of substrate on the HTC between borophene sheets and provides a theoretical guidance for the design of near-field thermal radiation devices.展开更多
Photon tunneling effects give rise to surface waves,amplifying radiative heat transfer in the near-field regime.Recent research has highlighted that the introduction of nanopores into materials creates additional path...Photon tunneling effects give rise to surface waves,amplifying radiative heat transfer in the near-field regime.Recent research has highlighted that the introduction of nanopores into materials creates additional pathways for heat transfer,leading to a substantial enhancement of near-field radiative heat transfer(NFRHT).Being a direct bandgap semiconductor,GaN has high thermal conductivity and stable resistance at high temperatures,and holds significant potential for applications in optoelectronic devices.Indeed,study of NFRHT between nanoporous GaN films is currently lacking,hence the physical mechanism for adding nanopores to GaN films remains to be discussed in the field of NFRHT.In this work,we delve into the NFRHT of GaN nanoporous films in terms of gap distance,GaN film thickness and the vacuum filling ratio.The results demonstrate a 27.2%increase in heat flux for a 10 nm gap when the nanoporous filling ratio is 0.5.Moreover,the spectral heat flux exhibits redshift with increase in the vacuum filling ratio.To be more precise,the peak of spectral heat flux moves fromω=1.31×10^(14)rad·s^(-1)toω=1.23×10^(14)rad·s^(-1)when the vacuum filling ratio changes from f=0.1 to f=0.5;this can be attributed to the excitation of surface phonon polaritons.The introduction of graphene into these configurations can highly enhance the NFRHT,and the spectral heat flux exhibits a blueshift with increase in the vacuum filling ratio,which can be explained by the excitation of surface plasmon polaritons.These findings offer theoretical insights that can guide the extensive utilization of porous structures in thermal control,management and thermal modulation.展开更多
Thin films exhibit substantial potential in energy management and utilization as the development of micro-and nanofabrication technologies.It is well known that thermal radiation is one of the fundamental ways of ener...Thin films exhibit substantial potential in energy management and utilization as the development of micro-and nanofabrication technologies.It is well known that thermal radiation is one of the fundamental ways of energy transfer.However,the potential of hyperbolic films for radiative heat transfer is always ignored.Whether the radiative heat flux between hyperbolic films surpasses that of the bulk materials remains insufficiently explored.In this work,we theoretically investigate the radiative heat transfer between hexagonal boron nitride(hBN)at a separation from 20nm to 2μm.The results show that when the optical axis of hBN is oriented in-plane,the near-field radiative heat flux of hBN with a thickness of 10nm exceeds that of hBN bulk by 47%and exceeds the blackbody limit by two orders of magnitude at a gap distance of 20nm.The physical mechanism is attributed to the volume-confined hyperbolic polaritons can be excited in a higher wavevector space.Conversely,when the gap distance is 600nm,the heat flux between films is considerably lower than that of bulk material.This work opens up potential avenues for developing hyperbolic film-dependent thermal devices and strategies for thermal management.展开更多
The combination of advanced photoelectric detectors has rendered single-band camouflage materials ineffective,necessitating the development of infrared multispectral camouflage.However,the design and fabrication of ex...The combination of advanced photoelectric detectors has rendered single-band camouflage materials ineffective,necessitating the development of infrared multispectral camouflage.However,the design and fabrication of existing works remain complex as they usually require the integration of multiscale structures.Here,we introduce phase modulation into the infrared camouflage metasurfaces with metal-dielectric-metal configuration,enabling them to achieve camouflage across more bands.Based on this strategy,a simple but effective single-layer cascaded metasurface is demonstrated for the first time to achieve low reflection at multi-wavelength lasers,low infrared radiation in atmospheric windows,and broadband thermal management.As a proof-of-concept,a 4-inch sample with a minimum linewidth of 1.8μm is fabricated using photolithography.The excellent infrared multispectral camouflage performance is verified in experiments,showing low reflectance in 0.9–1.6μm,low infrared emissivity in mid-wavelength infrared(MWIR)and long-wavelength infrared(LWIR)bands,and high absorptance at the wavelength of 10.6μm.Meanwhile,broadband high emissivity in 5–8μm can provide high-performance radiative heat dissipation.When the input power is 1.57 W·cm^(-2),the surface/radiation temperature of the metasurface decreases by 5.3℃/18.7℃ compared to the reference.The proposed metasurface may trigger further innovation in the design and application of compact multispectral optical devices.展开更多
Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectificatio...Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To address this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.展开更多
The thermal radiation of micron-sized condensed phase particles plays a dominant role during the heat transfer process in aluminized Solid Rocket Motors(SRMs).Open research mainly focuses on the radiative properties o...The thermal radiation of micron-sized condensed phase particles plays a dominant role during the heat transfer process in aluminized Solid Rocket Motors(SRMs).Open research mainly focuses on the radiative properties of alumina particles while the study considering the presence of aluminum is lacking.In addition,the thermal radiation inside the SRM with consideration of the participating particles is seldom studied.In this work,the multiscale method of predicting the thermal environment inside SRMs is established from the particle radiation at microscale to the twophase flow and heat transfer at macroscale.The effective gray radiative properties of individual particles(alumina,aluminum,and hybrid alumina/aluminum)and particles cloud are investigated with the Mie theory and approximate method.Then a numerical method for predicting the thermal environment inside SRMs with considering particle radiation is established and applied in a subscale motor.The convective and radiative heat flux distributions along inner wall of motor are obtained,and it is found that the heat transfer in the combustion chamber is dominated by thermal radiation and the radiative heat flux is essentially a constant of 5.6–6.8 MW/m^(2).The convective heat transfer plays a dominant role in the nozzle and the heat flux reaches the maximum value of 11.2 MW/m^(2) near the throat.As the combustion efficiency of aluminum drops,the radiative heat flux remains unchanged in most regions and increases slightly along the diverging section wall of the nozzle.展开更多
The weighted-sum-of-gray-gas(WSGG)model and Mie theory are applied to study the influents of particle size on the radiative transfer in high temperature homogeneous gas-particle mixtures,such as the flame in aero-engi...The weighted-sum-of-gray-gas(WSGG)model and Mie theory are applied to study the influents of particle size on the radiative transfer in high temperature homogeneous gas-particle mixtures,such as the flame in aero-engine combustor.The radiative transfer equation is solved by the finite volume method.The particle size is assumed to obey uniform distribution and logarithmic normal(L-N)distribution,respectively.Results reveal that when particle size obeys uniform distribution,increasing particle size with total particle volume fraction fvunchanged will result in the decreasing of the absolute value of radiative heat transfer properties,and the effect of ignoring particle scattering will also be weakened.Opposite conclusions can be obtained when total particle number concentration N0 is unchanged.Moreover,if particle size obeys L-N distribution,increasing the narrowness indexσor decreasing the characteristic diameter Dˉwith the total particle volume fraction fvunchanged will increase the absolute value of radiative heat transfer properties.With total particle number concentration N0 unchanged,opposite conclusions for radiative heat source and incident radiation terms can be obtained except for radiative heat flux term.As a whole,the effects of particle size on the radiative heat transfer in the high-temperature homogeneous gas-particle mixtures are complicated,and the particle scattering cannot be ignoring just according to the particle size.展开更多
A radiative heat transfer mathematical model for a one-dimensional long furnace was set up in a through-type roller-hearth furnace （TTRHF） in compact strip production （CSP）. To accurately predict the heat exchange...A radiative heat transfer mathematical model for a one-dimensional long furnace was set up in a through-type roller-hearth furnace （TTRHF） in compact strip production （CSP）. To accurately predict the heat exchange in the furnace, modeling of the complex gas energy-balance equation in volume zones was considered, and the heat transfer model of heating slabs and wall lines was coupled with the radiative heat transfer model to identify the surface zonal temperature. With numerical simulation, the temperature fields of gas, slabs, and wall lines in the furnace under one typical working condition were carefully accounted and analyzed. The fundamental theory for analyzing the thermal process in TI＇RI-IF was provided.展开更多
In the post-Moore era, as the energy consumption of micro-nano electronic devices rapidly increases, near-field radiative heat transfer(NFRHT) with super-Planckian phenomena has gradually shown great potential for app...In the post-Moore era, as the energy consumption of micro-nano electronic devices rapidly increases, near-field radiative heat transfer(NFRHT) with super-Planckian phenomena has gradually shown great potential for applications in efficient and ultrafast thermal modulation and energy conversion. Recently, hyperbolic materials, an important class of anisotropic materials with hyperbolic isofrequency contours, have been intensively investigated. As an exotic optical platform, hyperbolic materials bring tremendous new opportunities for NFRHT from theoretical advances to experimental designs. To date, there have been considerable achievements in NFRHT for hyperbolic materials, which range from the establishment of different unprecedented heat transport phenomena to various potential applications. This review concisely introduces the basic physics of NFRHT for hyperbolic materials, lays out the theoretical methods to address NFRHT for hyperbolic materials, and highlights unique behaviors as realized in different hyperbolic materials and the resulting applications. Finally, key challenges and opportunities of the NFRHT for hyperbolic materials in terms of fundamental physics, experimental validations, and potential applications are outlined and discussed.展开更多
A new mathematical model is presented to study the heat and mass transfer characteristics of magnetohydrodynamic(MHD) Maxwell fluid flow over a convectively heated stretchable rotating disk. To regulate the fluid temp...A new mathematical model is presented to study the heat and mass transfer characteristics of magnetohydrodynamic(MHD) Maxwell fluid flow over a convectively heated stretchable rotating disk. To regulate the fluid temperature at the surface, a simple isothermal model of homogeneous-heterogeneous reactions is employed. The impact of nonlinear thermal radiative heat flux on thermal transport features is studied. The transformed nonlinear system of ordinary differential equations is solved numerically with an efficient method, namely, the Runge-Kutta-Felberg fourth-order and fifth-order(RKF45)integration scheme using the MAPLE software. Achieved results are validated with previous studies in an excellent way. Major outcomes reveal that the magnetic flux reduces the velocity components in the radial, angular, and axial directions, and enhances the fluid temperature. Also, the presence of radiative heat flux is to raise the temperature of fluid. Further, the strength of homogeneous-heterogeneous reactions is useful to diminish the concentration of reaction.展开更多
The absorption process of radiative heat in its transmission medium and the effect of ultra-attenuation on the radiative characteristics are analyzed in detail. A method of ultra-attenuation to enhance the radiative c...The absorption process of radiative heat in its transmission medium and the effect of ultra-attenuation on the radiative characteristics are analyzed in detail. A method of ultra-attenuation to enhance the radiative characteristics of the medium is proposed. It is proved that decreasing the particle size of coatings can increase the transmission depth of radiative heat and get higher emissivity and absorptivity both theoretically and practically. Ultra-attenuation and nanocrystallization will bring a brilliant prospect to the development of radiative coatings.展开更多
Hyperbolic metamaterials alternately stacked by graphene and silicon（Si） are proposed and theoretically studied to investigate the contribution of terahertz（THz） waves to near-field radiative transfer. The results...Hyperbolic metamaterials alternately stacked by graphene and silicon（Si） are proposed and theoretically studied to investigate the contribution of terahertz（THz） waves to near-field radiative transfer. The results show that the heat transfer coefficient can be enhanced several times in a certain THz frequency range compared with that between graphene-covered Si bulks because of the presence of a continuum of hyperbolic modes. Moreover, the radiative heat transfer can also be enhanced remarkably for the proposed structure even in the whole THz range. The hyperbolic dispersion of the graphenebased hyperbolic metamaterial can be tuned by varying the chemical potential or the thickness of Si, with the tunability of optical conductivity and the chemical potential of graphene fixed. We also demonstrate that the radiative heat transfer can be actively controlled in the THz frequency range.展开更多
基金support of the National Natural Science Foundation of China(Nos.52003248 and 82004001)the China Postdoctoral Science Foundation(Nos.2018M642780 and 2021T140613)+1 种基金the Open-ing Project of State Key Laboratory of Polymer Materials Engineer-ing(Sichuan University)(No.sklpme2019-4-31)the Key Research and Development and Promotion projects of Henan Province(No.202102210032)are gratefully acknowledged.
文摘Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical conductivity,high solar absorptivity,and low infrared emissivity at the same time are rare in na-ture,which are highly anticipated and of great significance for highly efficient electric/solar heating.In this work,we demonstrate that Ti_(3)C_(2)T_(x) MXene with low IR emissivity(14.5%)fills the gap in the absence of the above materials,exhibiting a remarkable electric/solar heating performance.The saturated heating temperature of Ti_(3)C_(2)T_(x) film reaches a record-high value of 201°C at a low driving voltage of 1.5 V,and reaches 84.3°C under practical solar irradiation(750 W/m^(2))with a high solar to the thermal conversion efficiency of 75.3%,which is far superior to other reported materials.Meanwhile,the low IR emissivity endows Ti_(3)C_(2)T_(x) with a remarkable passive radiative heating capability of 7.0°C,ensuring zero-energy heating without electric/solar energy supply.The intrinsic characteristic of high electrical conductivity,high solar absorptivity,and low IR emissivity makes Ti_(3)C_(2)T_(x) unique existence in nature,which is highly promising for all-day and all-weather energy-saving heating.
基金The study was supported by the National Natural Science Foundation of China[grant numbers 41831175 and 41530425]the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA20060501]+1 种基金the Key Deployment Project of the Centre for Ocean Mega-Research of Science,Chinese Academy of Sciences[grant number COMS2019Q03]the Second Tibetan Plateau Scientific Expedition and Research(STEP)program[grant number 2019QZKK0102].
文摘Based on the 1%CO_(2) experiment of CMIP6,in response to increasing CO_(2),the summer-mean radiative heating(RH)over the global monsoon area(MA)generally features an increasing response in the mid-troposphere and a decreasing response in the lower and upper troposphere.The pressure level of the maximum RH increase over the Asian MA is the highest and largest in range(500–775 hPa);the maximum increases over the North African,South American,and Australian MA are at 550–600 hPa;throughout the North American MA,the maximum heating increase is at 600 hPa;and the levels of the maximum over South Africa are 600 and 775 hPa.For most of the global MA,the maximum enhancement of RH is at 500,550,and 600 hPa.It is mainly led by the increase in cloud water at and above the maximum level and the decrease in cloud water below,which leads to similar changes in total cloud mass.Because of the longwave heating(cooling)effect at the cloud base(top),the RH enhancements peak at those levels.For the northeast part of the Asian MA and southeast part of the South African MA,RH enhancement peaks at 700 and 775 hPa,mainly attributable to the cloud water reduction below.The reduction leads to similar changes in total cloud.Due to the longwave cooling effect at the cloud top,the reduction contributes to the RH enhancement at the corresponding maximum levels.
基金National Natural Science Foundation of China,Grant/Award Number:52003248Henan Province Youth Health Science and Technology Innovation Talent Training Program,Grant/Award Number:YQRC2023007+1 种基金Henan Province Excellent Youth Science Fund,Grant/Award Number:242300421064Joint Fund Predominant Discipline Cultivation Project of Henan Province,Grant/Award Number:232301420036.
文摘Switchable radiative cooling/heating holds great promise for mitigating the global energy and environmental crisis.Here,we reported a cost-effective,high-strength Janus film through surface optical engineering waste paper with one side decorated by a hydrophobic polymeric cooling coating consisting of micro/nanopore/particle hierarchical structure and the other side coated with hydrophilic MXene nanosheets for heating.The cooling surface demonstrates high solar reflectivity(96.3%)and infrared emissivity(95.5%),resulting in daytime/nighttime sub-ambient radiative cooling of 6℃/8℃with the theoretical cooling power of 100.6 and 138.5Wm^(−2),respectively.The heating surface exhibits high solar absorptivity(83.7%)and low infrared emissivity(15.2%),resulting in excellent radiative heating capacity for vehicle charging pile(~6.2℃)and solar heating performance.Impressively,the mechanical strength of Janus film increased greatly by 563%compared with that of pristine waste paper,which is helpful for its practical applications in various scenarios for switchable radiative thermal management through mechanical flipping.Energy-saving simulation results reveal that significant total energy savings of up to 32.4MJm^(−2) can be achieved annually(corresponding to the 12.4%saving ratio),showing the immense importance of reducing carbon footprint and promoting carbon neutrality.
基金support from the Research Grants Council of the Hong Kong Special Administrative Region,China(PolyU152052/21E)Green Tech Fund of Hong Kong(Project No.:GTF202220106)+1 种基金Innovation and Technology Fund of the Hong Kong Special Administrative Region,China(ITP/018/21TP)PolyU Endowed Young Scholars Scheme(Project No.:84CC).
文摘Maintaining thermal comfort within the human body is crucial for optimal health and overall well-being.By merely broadening the setpoint of indoor temperatures,we could significantly slash energy usage in building heating,ventilation,and air-conditioning systems.In recent years,there has been a surge in advancements in personal thermal management(PTM),aiming to regulate heat and moisture transfer within our immediate surroundings,clothing,and skin.The advent of PTM is driven by the rapid development in nano/micro-materials and energy science and engineering.An emerging research area in PTM is personal radiative thermal management(PRTM),which demonstrates immense potential with its high radiative heat transfer efficiency and ease of regulation.However,it is less taken into account in traditional textiles,and there currently lies a gap in our knowledge and understanding of PRTM.In this review,we aim to present a thorough analysis of advanced textile materials and technologies for PRTM.Specifically,we will introduce and discuss the underlying radiation heat transfer mechanisms,fabrication methods of textiles,and various indoor/outdoor applications in light of their different regulation functionalities,including radiative cooling,radiative heating,and dual-mode thermoregulation.Furthermore,we will shine a light on the current hurdles,propose potential strategies,and delve into future technology trends for PRTM with an emphasis on functionalities and applications.
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Financial support of the National Natural Science Foundation of China(No.52003248)the China Postdoctoral Science Foundation(Nos.2018M642780 and 2021T140613)+1 种基金the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University)(No.sklpme2019-4-31)the Key Research and Development and Promotion projects of Henan Province(No.202102210032)are gratefully acknowledged.
文摘Visible transparent yet low infrared-emissivity(ε)polymeric materials are highly anticipated in many applications,whereas the fabrication of which remains a formidable challenge.Herein,visible transparent,flexible,and low-εpolymeric films were fabricated by nanocoating decoration of indium tin oxide(ITO)and MXene on polyethylene terephthalate(PET)film surface through magnetron sputtering and spray coating,respectively.The obtained PET-ITO@MXene(PET-IM)film exhibits lowεof 24.7%and high visible transmittance exceeding 50%,endowing it with excellent visible transparent infrared stealthy by reducing human skin radiation temperature from 32 to 20.8°C,and remarkable zero-energy passive radiative heating capability(5.7°C).Meanwhile,the transparent low-εPET-IM film has high solar absorptivity and electrical conductivity,enabling superior solar/electric to thermal conversion performance.Notably,the three heating modes of passive radiative and active solar/electric can be integrated together to cope with complex heating scenarios.These visible transparent low-εpolymeric films are highly promising in infrared stealth,building daylighting and thermal management,and personal precision heating.
基金supported by the National Natural Science Foundation of China(Grant Nos.40875084and40705012)the National Key Technologies R&D Program of China(Grant No.2008BAC40B00)
文摘The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the lower atmosphere over central China to be smaller than the fluxes over southern and northern China by generating more clouds. The existence of a larger quantity of clouds over central China reflects a greater amount of solar radiation back into space. The vertical gradients of upward shortwave radiative fluxes in the atmosphere below 8 km are greater than those above 8 km. The latitudinal-altitude distributions of downward longwave radiative fluxes show a slantwise decreasing trend from low latitudes to high latitudes that gradually weaken in the downward direction. The upward longwave radiative fluxes also weaken in the upward direction but with larger gradients. The maximum heating rates by solar radiation and cooling rates by longwave infrared radiation are located over 28 40°N at 7 8 km mean sea level (MSL), and they are larger than the rates in the northern and southern regions. The heating and cooling rates match well both vertically and geographically.
基金This research was financially supported by the Beijing Municipal Natural Science Foundation(No.2212041)National Natural Science Foundation of China(No.51804232).
文摘Convective heat transfer and radiative heat transfer are two essential heat transfer modes in the heating process of steel;it is important to understand the role of them during the heating process clearly.The effects of the convective and radiative heat transfer during the heating process of a cast ingot in a tubular furnace have been studied by the designed natural and forced convection experiments and mathematical simulations.The heating time for the center of the ingot to reach the furnace temperature is decreased with the increase in furnace temperature.According to the experimental and simulation results,a model is proposed regarding the role of radiative and convective heat transfer in the heating process.At low temperature,the convective heat transfer plays a dominant role,while at high temperature,the influence of radiative heat transfer is larger.And a critical temperature exists between them.The forced convective heat transfer can enhance the influence of the convective heat transfer.The critical temperature can be shifted to higher temperatures.
基金Project supported by the Natural Science Foundation of Henan Province,China(Grant No.232102231023)。
文摘Near-field radiative heat transfer(NFRHT)has the potential to exceed the blackbody limit by several orders of magnitude,offering significant opportunities for energy harvesting.In this study,we have examined the NFRHT between two borophene sheets through the calculation of heat transfer coefficient(HTC).Due to the tunneling of evanescent waves,borophene sheet allows for enhanced heat flux and adjustable NFRHT by varying its electron density and electron relaxation time.Additionally,the near field coupling is further examined when the borophene is deposited on dielectric or lossy substrates.The maximum HTC is closely related to the real part of the dielectric substrate.As a case study,the HTCs on the lossy substrate of MoO_(3),ZnSe,and SiC are calculated for comparisons.Our results indicate that MoO_(3)is the optimal substrate to get the enhanced energy transfer coefficient.It results in a remarkable value of 1737 times higher than the blackbody limit owing to the enhanced photon tunneling probability.Thus,our study reveals the effect of substrate on the HTC between borophene sheets and provides a theoretical guidance for the design of near-field thermal radiation devices.
基金Project supported by the National Natural Science Foundation of China (Grant No.52106099)the Natural Science Foundation of Shandong Province (Grant No.ZR2022YQ57)the Taishan Scholars Program。
文摘Photon tunneling effects give rise to surface waves,amplifying radiative heat transfer in the near-field regime.Recent research has highlighted that the introduction of nanopores into materials creates additional pathways for heat transfer,leading to a substantial enhancement of near-field radiative heat transfer(NFRHT).Being a direct bandgap semiconductor,GaN has high thermal conductivity and stable resistance at high temperatures,and holds significant potential for applications in optoelectronic devices.Indeed,study of NFRHT between nanoporous GaN films is currently lacking,hence the physical mechanism for adding nanopores to GaN films remains to be discussed in the field of NFRHT.In this work,we delve into the NFRHT of GaN nanoporous films in terms of gap distance,GaN film thickness and the vacuum filling ratio.The results demonstrate a 27.2%increase in heat flux for a 10 nm gap when the nanoporous filling ratio is 0.5.Moreover,the spectral heat flux exhibits redshift with increase in the vacuum filling ratio.To be more precise,the peak of spectral heat flux moves fromω=1.31×10^(14)rad·s^(-1)toω=1.23×10^(14)rad·s^(-1)when the vacuum filling ratio changes from f=0.1 to f=0.5;this can be attributed to the excitation of surface phonon polaritons.The introduction of graphene into these configurations can highly enhance the NFRHT,and the spectral heat flux exhibits a blueshift with increase in the vacuum filling ratio,which can be explained by the excitation of surface plasmon polaritons.These findings offer theoretical insights that can guide the extensive utilization of porous structures in thermal control,management and thermal modulation.
基金supported by the National Natural Science Foundation of China(52106099)the Natural Science Foundation of Shandong Province(ZR2022YQ57)the Taishan Scholars Program.
文摘Thin films exhibit substantial potential in energy management and utilization as the development of micro-and nanofabrication technologies.It is well known that thermal radiation is one of the fundamental ways of energy transfer.However,the potential of hyperbolic films for radiative heat transfer is always ignored.Whether the radiative heat flux between hyperbolic films surpasses that of the bulk materials remains insufficiently explored.In this work,we theoretically investigate the radiative heat transfer between hexagonal boron nitride(hBN)at a separation from 20nm to 2μm.The results show that when the optical axis of hBN is oriented in-plane,the near-field radiative heat flux of hBN with a thickness of 10nm exceeds that of hBN bulk by 47%and exceeds the blackbody limit by two orders of magnitude at a gap distance of 20nm.The physical mechanism is attributed to the volume-confined hyperbolic polaritons can be excited in a higher wavevector space.Conversely,when the gap distance is 600nm,the heat flux between films is considerably lower than that of bulk material.This work opens up potential avenues for developing hyperbolic film-dependent thermal devices and strategies for thermal management.
基金financial supports from the National Natural Science Foundation of China(Grant Nos.51925503&52105575)the Fundamental Research Funds for the Central Universities(Grant No.QTZX23063)+2 种基金the Aeronautical Science Foundation of China(Grant No.2022Z073081001)the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20232028)the Open Research Funds of State Key Laboratory of Intelligent Manufacturing Equipment and Technology(Grant No.IMETKF2024008).
文摘The combination of advanced photoelectric detectors has rendered single-band camouflage materials ineffective,necessitating the development of infrared multispectral camouflage.However,the design and fabrication of existing works remain complex as they usually require the integration of multiscale structures.Here,we introduce phase modulation into the infrared camouflage metasurfaces with metal-dielectric-metal configuration,enabling them to achieve camouflage across more bands.Based on this strategy,a simple but effective single-layer cascaded metasurface is demonstrated for the first time to achieve low reflection at multi-wavelength lasers,low infrared radiation in atmospheric windows,and broadband thermal management.As a proof-of-concept,a 4-inch sample with a minimum linewidth of 1.8μm is fabricated using photolithography.The excellent infrared multispectral camouflage performance is verified in experiments,showing low reflectance in 0.9–1.6μm,low infrared emissivity in mid-wavelength infrared(MWIR)and long-wavelength infrared(LWIR)bands,and high absorptance at the wavelength of 10.6μm.Meanwhile,broadband high emissivity in 5–8μm can provide high-performance radiative heat dissipation.When the input power is 1.57 W·cm^(-2),the surface/radiation temperature of the metasurface decreases by 5.3℃/18.7℃ compared to the reference.The proposed metasurface may trigger further innovation in the design and application of compact multispectral optical devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.12364008)the Ph.D.Research Startup Foundation of Yan’an University(Grant No.YDBK2019-54)the Yan’an High-level Talent Special Project(Grant No.2019263166)。
文摘Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To address this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.
基金supported by the Innovative Talents Support Plan of China Postdoctoral Foundation(No.BX20180244)National Natural Science Foundation of China(No.51825604)the Fundamental Research Funds for the Central Universities of China(No.xjj2018029)。
文摘The thermal radiation of micron-sized condensed phase particles plays a dominant role during the heat transfer process in aluminized Solid Rocket Motors(SRMs).Open research mainly focuses on the radiative properties of alumina particles while the study considering the presence of aluminum is lacking.In addition,the thermal radiation inside the SRM with consideration of the participating particles is seldom studied.In this work,the multiscale method of predicting the thermal environment inside SRMs is established from the particle radiation at microscale to the twophase flow and heat transfer at macroscale.The effective gray radiative properties of individual particles(alumina,aluminum,and hybrid alumina/aluminum)and particles cloud are investigated with the Mie theory and approximate method.Then a numerical method for predicting the thermal environment inside SRMs with considering particle radiation is established and applied in a subscale motor.The convective and radiative heat flux distributions along inner wall of motor are obtained,and it is found that the heat transfer in the combustion chamber is dominated by thermal radiation and the radiative heat flux is essentially a constant of 5.6–6.8 MW/m^(2).The convective heat transfer plays a dominant role in the nozzle and the heat flux reaches the maximum value of 11.2 MW/m^(2) near the throat.As the combustion efficiency of aluminum drops,the radiative heat flux remains unchanged in most regions and increases slightly along the diverging section wall of the nozzle.
基金supported by the National Natural Science Foundation of China (No: 51806103)Jiangsu Provincial Natural Science Foundation(No: BK20170800)Open Funds of Aero-engine Thermal Environment and Structure Key Laboratory of Ministry of Industry and Information Technology (No. CEPE2018005)
文摘The weighted-sum-of-gray-gas(WSGG)model and Mie theory are applied to study the influents of particle size on the radiative transfer in high temperature homogeneous gas-particle mixtures,such as the flame in aero-engine combustor.The radiative transfer equation is solved by the finite volume method.The particle size is assumed to obey uniform distribution and logarithmic normal(L-N)distribution,respectively.Results reveal that when particle size obeys uniform distribution,increasing particle size with total particle volume fraction fvunchanged will result in the decreasing of the absolute value of radiative heat transfer properties,and the effect of ignoring particle scattering will also be weakened.Opposite conclusions can be obtained when total particle number concentration N0 is unchanged.Moreover,if particle size obeys L-N distribution,increasing the narrowness indexσor decreasing the characteristic diameter Dˉwith the total particle volume fraction fvunchanged will increase the absolute value of radiative heat transfer properties.With total particle number concentration N0 unchanged,opposite conclusions for radiative heat source and incident radiation terms can be obtained except for radiative heat flux term.As a whole,the effects of particle size on the radiative heat transfer in the high-temperature homogeneous gas-particle mixtures are complicated,and the particle scattering cannot be ignoring just according to the particle size.
文摘A radiative heat transfer mathematical model for a one-dimensional long furnace was set up in a through-type roller-hearth furnace （TTRHF） in compact strip production （CSP）. To accurately predict the heat exchange in the furnace, modeling of the complex gas energy-balance equation in volume zones was considered, and the heat transfer model of heating slabs and wall lines was coupled with the radiative heat transfer model to identify the surface zonal temperature. With numerical simulation, the temperature fields of gas, slabs, and wall lines in the furnace under one typical working condition were carefully accounted and analyzed. The fundamental theory for analyzing the thermal process in TI＇RI-IF was provided.
基金supported by the Natural Science Foundation of Shandong Province (ZR2020LLZ004)the National Natural Science Foundation of China (Grant No.52106099),the National Natural Science Foundation of China (Grant No.52076056)the Fundamental Research Funds for the Central Universities (Grant No.AUGA5710094020)。
文摘In the post-Moore era, as the energy consumption of micro-nano electronic devices rapidly increases, near-field radiative heat transfer(NFRHT) with super-Planckian phenomena has gradually shown great potential for applications in efficient and ultrafast thermal modulation and energy conversion. Recently, hyperbolic materials, an important class of anisotropic materials with hyperbolic isofrequency contours, have been intensively investigated. As an exotic optical platform, hyperbolic materials bring tremendous new opportunities for NFRHT from theoretical advances to experimental designs. To date, there have been considerable achievements in NFRHT for hyperbolic materials, which range from the establishment of different unprecedented heat transport phenomena to various potential applications. This review concisely introduces the basic physics of NFRHT for hyperbolic materials, lays out the theoretical methods to address NFRHT for hyperbolic materials, and highlights unique behaviors as realized in different hyperbolic materials and the resulting applications. Finally, key challenges and opportunities of the NFRHT for hyperbolic materials in terms of fundamental physics, experimental validations, and potential applications are outlined and discussed.
文摘A new mathematical model is presented to study the heat and mass transfer characteristics of magnetohydrodynamic(MHD) Maxwell fluid flow over a convectively heated stretchable rotating disk. To regulate the fluid temperature at the surface, a simple isothermal model of homogeneous-heterogeneous reactions is employed. The impact of nonlinear thermal radiative heat flux on thermal transport features is studied. The transformed nonlinear system of ordinary differential equations is solved numerically with an efficient method, namely, the Runge-Kutta-Felberg fourth-order and fifth-order(RKF45)integration scheme using the MAPLE software. Achieved results are validated with previous studies in an excellent way. Major outcomes reveal that the magnetic flux reduces the velocity components in the radial, angular, and axial directions, and enhances the fluid temperature. Also, the presence of radiative heat flux is to raise the temperature of fluid. Further, the strength of homogeneous-heterogeneous reactions is useful to diminish the concentration of reaction.
文摘The absorption process of radiative heat in its transmission medium and the effect of ultra-attenuation on the radiative characteristics are analyzed in detail. A method of ultra-attenuation to enhance the radiative characteristics of the medium is proposed. It is proved that decreasing the particle size of coatings can increase the transmission depth of radiative heat and get higher emissivity and absorptivity both theoretically and practically. Ultra-attenuation and nanocrystallization will bring a brilliant prospect to the development of radiative coatings.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11704175,11664024,and 61367006)
文摘Hyperbolic metamaterials alternately stacked by graphene and silicon（Si） are proposed and theoretically studied to investigate the contribution of terahertz（THz） waves to near-field radiative transfer. The results show that the heat transfer coefficient can be enhanced several times in a certain THz frequency range compared with that between graphene-covered Si bulks because of the presence of a continuum of hyperbolic modes. Moreover, the radiative heat transfer can also be enhanced remarkably for the proposed structure even in the whole THz range. The hyperbolic dispersion of the graphenebased hyperbolic metamaterial can be tuned by varying the chemical potential or the thickness of Si, with the tunability of optical conductivity and the chemical potential of graphene fixed. We also demonstrate that the radiative heat transfer can be actively controlled in the THz frequency range.
