250 results about "Radiative cooling" patented technology

The invention discloses a passive radiation refrigeration coating and a preparation method thereof, and relates to the technical field of industrial coatings. Comprising a fluoroacrylate emulsion, hollow glass beads, nano titanium dioxide, flaky silicon dioxide aerogel powder, polytetrafluoroethylene micro powder, hydroxyl-terminated polydimethylsiloxane, a hydroxyl acrylic acid modified silane coupling agent, a super-hydrophobic modified fluorosilicone surface additive, nano cerium oxide, aluminum fluoride doped zinc oxide infrared enhancement powder and deionized water. The paint is prepared on the basis of the formula. According to the invention, a multi-scale spectrum regulation and control and surface self-cleaning system is constructed cooperatively, so that the synergistic effect of high reflection of a sunlight region and high emission of a middle infrared region is realized. The coating can maintain continuous passive refrigeration in a day and night period, the surface of the coating has self-cleaning capability and excellent ultraviolet aging resistance, and high reflectivity and high radiation emissivity can be maintained for a long time in a complex outdoor environment, so that the thermal management efficiency of buildings and equipment is remarkably improved.

The invention relates to the technical field of refrigeration material preparation, in particular to an efficient passive radiation refrigeration material suitable for a sub-super environment and a preparation method and application of the efficient passive radiation refrigeration material. The method comprises the following steps: uniformly mixing thermoplastic polyurethane, sunlight high-reflection inorganic particles and a phase change material in a solvent; after a chemical foaming agent is added, the obtained suspension liquid is heated and foamed in a confinement mold, and wet gel is formed; and finally, carrying out freeze drying treatment to obtain the composite porous aerogel. The prepared material has a micro-nano porous skeleton formed by TPU, and inorganic particles and PCM are uniformly dispersed in the skeleton wall. Through component cooperation and a special porous structure, the material has extremely high sunlight reflectivity and mid-infrared emissivity, self-adaptive temperature regulation and control are achieved through PCM phase change, the problem that refrigeration of a traditional material fails in the sub-environment such as the vertical surface is effectively solved, and efficient sub-super-environment heat management is achieved.

The invention discloses a dynamic self-adaptive radiation refrigeration material which comprises the following components in percentage by mass: 15-30% of matrix resin, 40-60% of a ternary function system, 1-3% of a dispersing agent, 2-5% of a cross-linking agent and the balance of deionized water, the ternary function system is composed of a temperature-sensitive block copolymer, phase change microcapsules and rare earth doped infrared emission particles according to the mass ratio of (1-2): (2-3): (1-1.5). According to the refrigeration material, when the environment temperature is higher than the low critical solution temperature of the temperature-sensitive copolymer, the temperature-sensitive chain segment shrinks to expose the rare earth particles, so that high reflectivity of sunlight and high emissivity of an atmospheric window are realized, and refrigeration is enhanced; when the temperature is lower than the phase-change temperature of the phase-change material, the temperature-sensitive chain segments stretch and wrap the rare earth particles, the infrared emissivity is reduced, heat loss is reduced through phase-change heat release, the dual functions of efficient refrigeration in summer and heat loss reduction in winter are achieved, and the applicability of the coating in an area with the large temperature difference is improved.

The invention discloses a high-reflection magnesium phosphate / aluminum phosphate radiation refrigeration material and a preparation method thereof, and relates to the technical field of radiation refrigeration materials. The preparation method of the high-reflection magnesium phosphate / aluminum phosphate radiation refrigeration material comprises the following steps: (1) mixing aluminum sec-butoxide and deionized water to prepare a solution A; mgCl2. 6H2O and deionized water are mixed to prepare a solution B; mixing the solution A and the solution B to obtain a solution C; (2) adding 3-sulfopropyl tetradecyl dimethyl betaine into the solution C to obtain a solution D; (3) stirring sodium pyrophosphate and deionized water into a solution E; mixing the solution E and the solution D to obtain a solution F; and (4) reacting the solution F at 150-180 DEG C, cooling, freeze-drying and grinding to obtain H, heating H to 300-400 DEG C at the rate of 3-4 DEG C / min, then heating H to 800-1300 DEG C at the rate of 7-10 DEG C / min, and keeping the temperature for 1-3 hours to obtain the product. The material prepared by the invention has excellent sunlight reflectivity and excellent mid-infrared emissivity, and shows excellent performance in the field of radiation refrigeration.

The present invention relates to a flexible thermoelectric device that may be combined and attached to a curved surface and generates an electromotive force based on a temperature difference between one surface and the other surface, and more particularly, to a flexible thermoelectric device having a radiative cooling part which improves power generation performance by increasing cooling efficiency of a cooling side through radiative cooling and minimizes a volume of a heat dissipating part, and a method of manufacturing a radiative cooling part.

The invention relates to the technical field of radiation refrigeration films, and discloses a porous polyvinylidene fluoride based composite radiation refrigeration film and a preparation method thereof. The method comprises the following steps: firstly, carrying out melt blending on PVDF, NaCl and ZnO nanoparticles and forming a film, then dissolving out NaCl through water washing, and constructing a continuous three-dimensional porous structure in a PVDF matrix; and immersing the obtained porous PVDF / ZnO membrane material into a methanol aqueous solution containing 2-methylimidazole, so that ZnO is subjected to a coordination reaction at the pore wall and is converted into the ZIF-8 nanocrystal in situ. In the thin film prepared by the steps, the micron-sized salt-induced pore structure, the nano-sized ZIF-8 particles and the interface of the ZIF-8 particles jointly form a multi-stage scattering network, so that the scattering ability of the thin film in the solar spectrum range of 0.25-2.5 microns can be remarkably enhanced, the high infrared emission performance of the PVDF matrix in an atmospheric window of 8-13 microns is maintained, and the thin film has high solar reflectivity and high infrared emissivity, and can be used for preparing the solar film. An excellent radiation refrigeration effect can be achieved, and the heat-dissipating material is suitable for being applied to building outer surfaces, equipment heat dissipation, individual heat management and the like.

The invention discloses a super-hydrophobic heat insulation / radiation refrigeration integrated fabric and a preparation method thereof.The method comprises the steps that firstly, a heat insulation layer is constructed on a base fabric through electrostatic spraying, specifically, PU and SCA are dissolved in DMF, SiO2 aerogel is added to form spraying liquid, a three-dimensional network structure is formed between aerogel and fibers through the synergistic cross-linking effect of SCA and PU, the aerogel is firmly anchored, and the heat insulation layer is formed; the adhesive force and the washability of the coating are improved. PVDF-HFP and ZrO2 nano-particles are blended and spun to form a composite structure with nano-fibers wrapping ceramic particles, particle aggregation is avoided, and the radiation refrigeration and heat insulation performance of PVDF-HFP and ZrO2 nano-particles are synergistically exerted. Finally, a substrate-heat insulation-refrigeration three-dimensional composite structure is formed through hot pressing treatment, chemical bonding of all the layers is achieved through SCA, the fabric has the characteristics of high strength, abrasion resistance, hydrophobicity, heat insulation and radiation refrigeration, and the problem that durability and comfort of a traditional material are difficult to achieve at the same time is solved.

The invention discloses a self-cleaning daytime radiation cooling coating and a preparation method thereof, and relates to the field of building exterior wall energy-saving coatings. The preparation method comprises the following steps: uniformly dispersing a first filler and a second filler in a butyl acetate solvent, sequentially adding a silane coupling agent and a third filler, uniformly dispersing, finally adding fluorocarbon resin and a curing system thereof, and dihydroxyl-terminated polydimethylsiloxane and a curing system thereof, and uniformly dispersing to obtain the self-cleaning daytime radiation cooling coating. The self-cleaning daytime radiation cooling coating prepared by the invention is high in hardness and strong in adhesive force, and also has a super-hydrophobic self-cleaning function and an optical property of realizing daytime radiation cooling. The coating is simple in preparation process, low in equipment requirement and suitable for large-scale production.

The invention relates to the technical field of coatings, and discloses a modified aerogel, a preparation method thereof and an application of the modified aerogel in a radiation refrigeration coating. The method comprises the following steps: in the presence of water, a solubilizer and an acid catalyst, carrying out hydrolysis reaction on a silicon source to obtain silica sol; in the presence of a base catalyst, contacting the silica sol with a rare earth oxide with a linear average particle size of 10-100 nm to carry out a gel reaction so as to obtain a modified wet gel; and drying the modified wet gel at normal pressure to obtain the modified aerogel, the adding amount of the rare earth oxide and the normal-pressure drying condition are controlled, so that the content of the rare earth oxide in the modified aerogel is 0.5-1 wt%. A coating prepared from the radiation refrigeration composition containing the modified aerogel prepared by the invention has the characteristics of high sunlight reflectivity, high atmospheric window emissivity and the like.

The invention discloses a passive radiation-cold storage composite box body and a preparation method. The box body sequentially comprises a composite radiation film, a heat insulation layer and a cold storage layer from outside to inside. The outer-layer radiation film is composed of an elastic organic matrix and high-reflection inorganic particles such as barium sulfate, has high solar reflectivity and mid-infrared high emissivity, and can effectively restrain solar absorption and achieve radiation heat dissipation in the daytime. The heat insulation layer is made of XPS, EPS, aerogel felt and other low-heat-conduction materials so as to reduce external heat transfer. Phase change microcapsules are dispersed in the cold storage layer, and flake graphite and other high-thermal-conductivity fillers can be added to improve the cold transfer efficiency and temperature uniformity. And the phase-change material realizes automatic cold storage and cold release through a latent heat mechanism, so that the temperature in the box body is kept stable. Through the synergistic effect of radiation refrigeration, heat insulation and phase change cold storage, long-time and recyclable passive cold chain temperature control is achieved, and the device has the advantages of being simple and convenient in structure, high in cost performance, flexible in application, uniform in internal temperature distribution and the like.

The invention provides a packaging front plate, a preparation method thereof and a photovoltaic module. The packaging front plate comprises a body which is of a transparent structure; the radiation cooling layer is arranged on the surface of one side of the body, the radiation cooling layer has light transmittance, and the face, away from the body, of the radiation cooling layer is provided with a lotus leaf surface imitating micro-nano structure. The radiation cooling layer can radiate heat to the external space, so that the working temperature of the photovoltaic module is effectively reduced, the photoelectric conversion efficiency can be improved, the photovoltaic module can be prevented from running at a high temperature, and the service life of the photovoltaic module can be prolonged; furthermore, a micro-nano structure imitating the lotus leaf surface is designed on the radiation cooling layer, attachment of water drops or dirt on the surface of the radiation cooling layer can be reduced, and therefore the surface of the radiation cooling layer is kept clean and dry, the problem that the power generation efficiency is reduced due to pollution can be avoided, the cleaning frequency can be reduced, and the power generation efficiency is improved. And therefore, the maintenance cost can be reduced.

The invention discloses a preparation method of an h-BN / BMSC daytime radiation refrigeration material, which comprises the following steps: (1) blending 39.9-66.5 parts by mass of few-layer h-BN nanosheets and 133 parts by mass of light calcined magnesia, and slowly stirring to obtain a mixed material; (2) dispersing an additive into 61 parts by mass of a magnesium sulfate heptahydrate solution, uniformly mixing, adding into the mixed material in the step (1), and stirring at a high speed to obtain slurry; and (3) putting the slurry obtained in the step (2) into a mold, and curing at room temperature to obtain the few-layer h-BN / BMSC composite material. The prepared gelling-based composite material has good radiation cooling performance and heat dissipation performance in an outdoor high-temperature environment, and can be used as a radiation cooling heat dissipation material with the temperature higher than the environment temperature. The passive cooling heat dissipation plate has important significance in improving the working efficiency of outdoor electronic equipment in a high-temperature environment, prolonging the service life and guaranteeing the reliability of a system.

The invention relates to the technical field of building energy conservation and water resource utilization, and discloses a multifunctional AKLBT dual-network hydrogel system and a preparation method and application thereof, the multifunctional AKLBT dual-network hydrogel system comprises AKLBT dual-network hydrogel and a PAN / PVDF coated CNTs / ppy composite photo-thermal layer; wherein the AKLBT dual-network hydrogel takes acrylamide and konjac glucomannan as monomers, and LiCl, BaSO4 and TiO2 are doped into the monomers; the PAN / PVDF-coated CNTs / ppy composite photo-thermal layer is attached to the surface of the hydrogel to construct a photo-thermal conversion interface. Through a three-in-one synergistic mechanism of radiation cooling, adsorption water collection and photo-thermal evaporation, zero-energy-consumption cooling of the building and efficient capture of atmospheric water resources are achieved, stable recycling can be achieved, and an integrated solution is provided for building hydrothermal collaborative management.

A colored bilayer sub-ambient radiative cooling coating designed to enhance solar reflectance and aesthetic coloration is introduced. The coating includes a white bottom layer containing TiO2 or ZrO2 nanoparticles, and hollow glass spheres dispersed in a polymer matrix, and a colored top layer containing SiO2 microspheres and fluorescent pigments selected from Sr2Si5N8:Eu2+, Y3A15O12:Ce3+, (Ba,Sr)SiO4:Eu2+, or SrO·Al2O3:Eu phosphors dispersed in a polymer matrix. This bilayer structure achieves an effective solar reflectance of at least 90% and reduces surface temperature by at least 3° C. compared to ambient air, providing energy-efficient cooling with aesthetic appeal.

This application provides a layered, environmentally friendly waterborne radiative cooling coating composition, belonging to the field of radiative cooling. The coating composition includes a waterborne radiative cooling primer, a topcoat, and a clear coat. The primer comprises 20-50 parts of a first waterborne emulsion, 10-20 parts of a narrow bandgap optical scatterer, and 10-20 parts of a wide bandgap optical scatterer. The topcoat comprises 20-50 parts of a second waterborne emulsion and 30-60 parts of a wide bandgap optical scatterer. The clear coat comprises 20-50 parts of a third waterborne emulsion. This coating utilizes a synergistic layering of primer / topcoat / clear coat and optimized wide bandgap filler gradation to achieve high solar reflectivity and mid-infrared emissivity at a thinner film thickness, resulting in significant passive cooling. The all-waterborne system disperses and dries at room temperature, resulting in low energy consumption and no VOC risk. The layered structure enhances adhesion, weather resistance, and self-cleaning properties. Compared to high-filler thick-coating processes, this application saves raw materials, energy consumption, and construction steps, extends maintenance cycles, and reduces total life-cycle costs.

The goal is to reduce the heating load in winter and the cooling load in summer. [Solution] The membrane structure building comprises a double membrane that constitutes the exterior of the building and has an inner membrane and an outer membrane having a radiative cooling function, and an air blower / discharge device that switches between an insulating mode in which air is blown into the double membrane to form an air layer between the inner membrane and the outer membrane, and a solar radiation shielding mode in which air is discharged from the double membrane to bring the inner membrane and the outer membrane into contact.

This invention discloses a photovoltaic module with dual passive assisted cooling and surface hydrophobicity, comprising: a photovoltaic module body; a light-transmitting radiative cooling layer disposed on the light-facing surface of the photovoltaic module body; the surface of the light-transmitting radiative cooling layer opposite to the photovoltaic module body having a microstructure; and a hygroscopic hydrogel disposed on the back surface of the photovoltaic module body. The photovoltaic module provided by this invention achieves a certain degree of cooling effect through the light-transmitting radiative cooling layer on its surface, while utilizing the hydrophobicity of the microstructure on the surface of the radiative cooling layer to provide good self-cleaning effect against dust and other dirt; furthermore, the hygroscopic hydrogel disposed on the back of the photovoltaic module achieves a good cooling effect through daytime moisture evaporation cooling.

The invention relates to a high-reflection passive radiation refrigeration paint and coating, a preparation method and a coating structure. The paint and the coating comprise deionized water, a functional additive, an inorganic functional reflection filler, a thermal radiation filler and a film-forming emulsion. The preparation method comprises the following steps: S1, weighing deionized water and a part of functional aids in parts by weight, and stirring and dispersing to obtain a first mixed solution; s2, sieving the inorganic functional reflective filler; s3, adding the inorganic functional reflective filler into the first mixed solution in parts by weight, and stirring and dispersing to obtain a second mixed solution; s4, synchronously adding the thermal radiation filler and the film-forming emulsion into the second mixed solution, and stirring and dispersing to obtain a third mixed solution; and S5, adding the rest functional additive into the third mixed solution to obtain the high-reflection passive radiation refrigeration coating. And S6, coating a base material with the high-reflection passive radiation refrigeration coating, and curing to obtain the high-reflection passive radiation refrigeration coating. The coating and the coating are excellent in refrigeration effect. The preparation method is simple in process, easy to operate and long in service life.

The present prevention provides a surface coating for cooling a surface by light scattering comprising a plurality of successive layers, each of the layers may be comprised of a plurality of spheres arranged to form a structure comprised of packed spheres. Each layer may have a different arrangement of packed spheres to create to a different light scattering property in each of the layers. The coating of the structures may also be formed by randomly packed spheres and the spheres may have a uniform diameter.

This invention discloses a self-cleaning radiative cooling coating based on biomass carbon quantum dots, its preparation method, and its application. The coating comprises a polymer film-forming resin, carbon quantum dots, and hollow glass microspheres; wherein the mass ratio of the polymer film-forming resin to the filler is 1:(0.1-0.5), and the mass ratio of the hollow glass microspheres to the carbon quantum dots is 1:(0.05-0.2). This invention synergistically enhances solar reflectivity through the photoluminescence properties of carbon quantum dots and the scattering properties of hollow glass microspheres, while simultaneously utilizing the synergistic effect of fluorinated resin and modified hollow glass microspheres to endow the coating with superhydrophobic self-cleaning function. A single layer of this coating can achieve a solar reflectivity >92%, mid-infrared emissivity >94%, and contact angle >150°, possessing both efficient daytime radiative cooling and long-lasting self-cleaning performance. It is particularly suitable for passive heat dissipation of outdoor equipment such as new energy vehicle charging piles, and features simple process, environmental friendliness, and excellent performance.

The utility model relates to the technical field of energy conservation, and provides an energy-saving car window projection system based on self-powered sensing and radiation refrigeration, which comprises a self-powered sensing device and a projection device used for projecting light rays to radiation refrigeration glass, and the projection device is provided with a power supply trigger interface and a projection lens. The power trigger interface is connected to the self-powered sensing device, and the projection lens faces the radiation refrigeration glass. The energy-saving car window projection system based on self-powered sensing and radiation refrigeration provided by the utility model can be favorable for realizing self power supply of the self-powered sensing device, saves energy consumption of temperature regulation and control through radiation refrigeration, and saves energy.

The embodiment of the invention discloses a highway tunnel entrance and exit photovoltaic safety helmet system and an operation and maintenance method thereof.The highway tunnel entrance and exit photovoltaic safety helmet system comprises a sectional type photovoltaic safety helmet unit and an intelligent operation and maintenance system, and the safety helmet unit is arranged in the extending direction of a tunnel entrance and divided into a visual transition section and a power generation strengthening section; the visual transition section adopts a photovoltaic module of which the surface is compounded with a spectral selectivity high-transmittance film, and the film is configured to highly transmit visible light so as to ensure the visual safety of driving and highly absorb near-infrared light for power generation; the power generation strengthening section adopts a radiation cooling type or efficient double-sided power generation assembly to maximize energy capture. The intelligent operation and maintenance system collects data in real time through a sensor network, and analyzes the data by using a machine learning model in an AI predictive maintenance platform so as to predict equipment faults in advance. The safety helmet integrates shading safety and driver light environment visual transition, and long-term reliable and economical operation of a system is guaranteed through intelligent operation and maintenance.

The invention discloses a photovoltaic-radiation refrigeration integrated glass curtain wall sunshade component, and relates to the technical field of photovoltaic building energy conservation, and the photovoltaic-radiation refrigeration integrated glass curtain wall sunshade component comprises a building wall surface, glass, an outer frame, a stand column, a sliding rail, an execution mechanism and a sunshade unit; the building wall surface is of a square structure and serves as a room enclosing wall and a positioning foundation; the glass is fixed on a peripheral building wall surface; the outer frame is fixed at the top end of the glass; the two stand columns are fixed to the two sides of the outer frame respectively, and a sliding rail is fixed in each stand column. The sunshade unit is arranged between the two sliding rails through an executing mechanism and comprises photovoltaic shutters, the sunshade area and angle are adjusted through the photovoltaic shutters, the radiation refrigeration function is implemented, and therefore the multiple functions of sunshade, power generation and heat dissipation are achieved, and dynamic balance of target indoor illumination and high power generation efficiency is continuously maintained. The technical effects of collaborative optimization of photovoltaic and sunshade functions, improvement of the heat dissipation effect, improvement of the regulation and control flexibility, meeting of the lighting requirement, maximization of the power generation efficiency and improvement of the energy-saving effect can be achieved at the same time.

The invention provides a water-based radiation refrigeration coating and a preparation method thereof, and belongs to the technical field of refrigeration coatings. The water-based radiation refrigeration coating comprises the following components: 25%-40% of a water-based emulsion, 10%-20% of polymethyl methacrylate powder, 10%-20% of functional filler, 0.1%-0.5% of a pH regulator, 0.1%-1.0% of a flatting agent, 0.1%-0.7% of a defoaming agent, 0.5%-1.8% of a thickening agent, 0.1%-0.5% of a dispersing agent, 0.1%-1.5% of a coalescing agent and the balance of deionized water. The water-based radiation refrigeration coating provided by the invention has high solar reflectivity (Rgt, 95%) and high infrared emissivity (ATSWgt, 95%), can effectively reflect and block sunlight, reduces the temperature of an external wall of a building through radiation heat dissipation and reduces the energy consumption of refrigeration equipment, and has important significance on energy conservation and environmental protection.

The application discloses a kind of space stable organic radiation refrigeration coatings and preparation method and application thereof, including optical layer and protective layer coated on the optical layer;The optical layer includes the following components by mass fraction:25~35% first polymer matrix, 35~45% first organic scattering particles, 20~40% first organic solvent;The protective layer includes the following components by mass fraction:60~75% second polymer matrix, 5~10% second organic scattering particles, 15~35% second organic solvent;Wherein, the first organic scattering particles and second organic scattering particles are independently selected from one or several of polytetrafluoroethylene, perfluoroolefin ether alkane, ethylene-tetrafluoroethylene copolymer respectively.In the meantime that space stability is guaranteed, coating weight is significantly reduced, and a new idea of considering performance and cost is provided for spacecraft thermal control.

The invention relates to the technical field of physical similar simulation, and particularly provides a physical simulation method for a lunar lava tube structure forming process, which comprises the following steps of: mixing a thermoplastic material and a condensation additive to prepare a simulation melt meeting a basalt lava rheology and thermodynamics similarity criterion; the low gravity effect, the high vacuum environment and the radiation cooling condition in the lunar environment are reproduced through an inclined flow channel and a thermal vacuum cavity, and the injection rate, the flow channel inclination angle and the target environment temperature of the simulated melt are determined by accurately matching dimensionless parameters such as the Peclet number, the dimension temperature and the Rayleigh number; under the condition, controlled flow and surface solidification crusting of the melt are simulated, and finally a cavity structure model is formed, so that physical research on the lunar lava tube structure forming process is realized. According to the method, the lava flow dynamic crusting and cavity forming process in the extreme lunar environment can be accurately reproduced, and a quantitative experimental data basis is provided for formation mechanism research and engineering application of the lunar lava tube.

The present invention relates to a large-area radiative cooling film and a method for manufacturing same. The radiative cooling film can be produced to exhibit excellent emissivity and infrared transmittance, by synthesizing highly crystalline single-crystal vanadium dioxide through a chemical vapor deposition method, and optimizing the structure thereof, such as the vanadium dioxide pattern, spacing, and the thickness of each layer. In addition, the method for manufacturing a radiative cooling film can improve process speed and stability through a film thinning process based on dry transfer, and enables the manufacture of a large-area radiative cooling film.

This invention relates to the field of physical similarity simulation technology, specifically providing a physical simulation method for the formation process of lunar lava tube structures. The method involves preparing a simulated melt that meets the rheological and thermodynamic similarity criteria of basaltic lava by mixing thermoplastic materials with condensation additives. The low-gravity effect, high-vacuum environment, and radiative cooling conditions under lunar conditions are reproduced using inclined flow channels and thermal vacuum cavities. By precisely matching dimensionless parameters such as Peckley number, dimensional temperature, and Rayleigh number, the injection rate, flow channel inclination angle, and target ambient temperature of the simulated melt are determined. Under these conditions, controlled melt flow and surface solidification crust formation are simulated, ultimately forming a cavity structure model. This allows for the physical study of the formation process of lunar lava tube structures. This invention can accurately reproduce the dynamic crust formation and cavity formation process of lava flow under extreme lunar conditions, providing a quantitative experimental data basis for the study of the formation mechanism of lunar lava tubes and their engineering applications.

The invention provides a Janus nanofiber membrane with hydrophobic / hydrophilic asymmetric wettability and a preparation method of the Janus nanofiber membrane. Silicon dioxide nanoparticles are formed on a polyurethane fiber membrane in situ, polyurethane electrostatic spinning is carried out by taking the silicon dioxide nanoparticles as a receiving substrate, and a hydrophobic polyurethane nanofiber layer is formed. The Janus nanofiber membrane has the advantages that the humidity regulation and control performance and the temperature regulation and control performance of the Janus nanofiber membrane are synergistically improved, the one-way water delivery capacity is achieved, the sunlight reflectivity and the intermediate infrared emissivity are greatly improved, the passive radiation cooling performance is good, the fiber orientation is regulated and controlled, the heat and humidity regulation and control performance, the sunlight reflectivity and the intermediate infrared emissivity of the Janus nanofiber membrane can be further improved, and the application prospect is wide. Therefore, the heat-insulating fabric can be applied to various application places.

This invention discloses a polyvinyl alcohol-based radiation-cooled porous material and its preparation method, belonging to the field of new materials. The material is prepared from a foaming system comprising an aqueous solution of polyvinyl alcohol, hydrophilic silica, a shrinkage-reducing agent, a foam stabilizer, polyethyleneimine, epichlorohydrin, and sodium dodecyl sulfate, through mechanical stirring foaming, heating curing, and atmospheric pressure drying. This invention effectively suppresses defects such as volume shrinkage, internal cracking, and skin separation in porous materials under atmospheric pressure drying conditions through the synergistic effect of the shrinkage-reducing agent and the foam stabilizer, avoiding the complex process of traditional freeze-drying. The porous material possesses both a high solar reflectivity of 93%–98% and an average infrared emissivity of over 97% within the 8–13 μm atmospheric window, enabling a cooling effect 10–20°C lower than ambient temperature without consuming additional energy, thus possessing significant practical application value.