RADIATIVE COOLING STRUCTURE AND METHOD OF USING THE SAME

Abstract

A radiative cooling structure for achieving day-time radiative cooling is disclosed. The radiative cooling structure includes reflective layers sandwiching an emissive layer. The emissive layer includes a polymer. The emissive layer includes non-polymer particles arranged or distributed in a matrix or non-matrix fashion. The reflective layers reflect solar light, and the emissive layer having the non-polymer particles transmits solar radiation and emits infrared radiation. The radiative cooling structure releases the heat in the form of thermal radiation and lowers or maintains the temperature of an object or surface the radiative cooling structure is in thermal contact with.

Description

FIELD OF THE INVENTION

The present invention generally relates to radiative cooling structures. More particularly, the present invention relates to a radiative cooling structure for removing heat from a body by selective thermal radiation. The present invention enables and provides a product and/or process that mitigates climate change by being designed to: (a) remove greenhouse gases already present in the atmosphere; (b) reduce and/or prevent additional greenhouse gas emissions; and/or (c) monitor, track, and/or verify greenhouse gas emission reductions.

DESCRIPTION OF THE RELATED ART

It is known that cooling contributes significantly to end-use of energy and is a major determining factor of peak electricity demand. In the United States, air conditioning alone accounts for nearly fifteen percent of the primary energy used by buildings. Different cooling methods are used based on the energy requirements and available resources such as cost and equipment.

Use of conventional cooling methods to operate heavy energy dependent industries is costly. For example, mining of digital currency and transportation of agricultural products require huge investment to cater to enormous resources and equipment needed. Further, the conventional cooling methods typically occupy substantial room, requiring immobile specialized equipment and continuous active input of various resources. For instance, the facilities cooled with forced air-cooling require powered blower installation and electricity supply to sustain continuous operation. An example of conventional cooling methods includes the use of hydro-cooling system. The hydro-cooling system requires a dip tank or shower system engineered to cool limited objects that are not moisture sensitive, bacterial treatment on cooling water to meet sanitary needs, and water supply to sustain operation.

Another technique used for cooling is passive radiative cooling. The passive radiative cooling introduces a cost-free method to draw heat from surfaces and radiate it into space as infrared radiation. The passive radiative cooling follows the strategy that cools without any electricity input could have a significant impact on global energy consumption. To achieve cooling, one needs to be able to reach and maintain the temperature below that of the ambient air. In passive radiative cooling, a device is exposed to the sky to radiate heat to outer space through a transparency window in the atmosphere between 8 and 13 micrometres (μm).

Although the passive radiative cooling is effective, only radiation at wavelengths between 8-13 μm can effectively dispense heat through an “atmosphere window”, also known as an “atmospheric transmission window” or an “atmospheric transparent window” into space due to the atmospheric composition of the Earth. All materials at room temperature emit infrared at wavelengths between 5-15 μm and can practice night-time passive radiative cooling, in daytime such cooling effect is counteracted by heat conveyed by solar radiance. Daytime radiative cooling, however, poses a unique challenge as most conventional material. Solar radiance counteracts traditional materials radiative cooling and effectively heats the surface.

Dr. Zhai et al in “Scalable-manufactured randomized glass polymer hybrid metamaterial for daytime radiative cooling. Science 355, 1062-1066 (2017)” discloses “Radi-Cool”, a glass-polymer hybrid metamaterial capable of daytime radiative cooling. The glass-polymer hybrid metamaterial is capable of achieving daytime radiative cooling by rejecting solar radiance and dispensing heat via vibrating in both magnetic and electronic modes, and its randomized glass-polymer hybrid structure allows scalable production. Dr. Zhai et al discussed embedding resonant polar dielectric microspheres randomly in a polymeric matrix, resulting in a metamaterial that is fully transparent to the solar spectrum while having an infrared emissivity greater than 0.93 across the atmospheric window. When backed with a silver coating, the metamaterial shows a noontime radiative cooling power of 93 watts per square meter under direct sunshine. More critically, we demonstrated high-throughput, economical roll-to-roll manufacturing of the metamaterial, which is vital for promoting radiative cooling as a viable energy technology.

Further, Aaswath P. Raman et al in “Passive radiative cooling below ambient air temperature under direct sunlight” discloses a thermal photonic approach, whereby they discussed introducing an integrated photonic solar reflector and thermal emitter consisting of seven layers of HfO₂ and SiO₂ that reflects 97 percent of incident sunlight while emitting strongly and selectively in the atmospheric transparency window. Aaswath P. Raman et al demonstrated a tailored, photonic approach that can fundamentally enable new technological possibilities for energy efficiency. Further, the cold darkness of the Universe can be used as a renewable thermodynamic resource, even during the hottest hours of the day.

Furthermore, a Chinese Patent No. 110734227, entitled “Radiation-resistant ceramic fiber heat-insulating composite material and preparation method thereof” discloses a radiation-resistant ceramic fiber thermal insulation composite material. The radiation-resistant ceramic fiber thermal insulation composite material of the present invention has the characteristics of ultra-low thermal conductivity, ultra-low moisture absorption rate, and ultra-high hydrophobicity, and will not corrode austenitic stainless steel. It can well solve the problem of existing inorganic fiber types. The material has problems such as high thermal conductivity, easy moisture absorption, and high corrosiveness, which can better ensure the full performance of the technical performance of military and civilian equipment and facilities. The invention also provides a method for preparing radiation-resistant ceramic fiber insulation composite materials. The method is simple to operate, does not require large-scale industrial equipment, and is suitable for industrial production.

In addition, a Japanese Patent No. 3381742, entitled “LIGHT ABSORBING AND THERMAL ENERGY STORING FAR INFRARED RADIATING FIBER AND ITS PRODUCTION” discloses light absorbing and thermal energy storing fibers comprising light absorbing and thermal energy storing and far infrared radiating iron oxide-based ceramics in a fiber-forming organic polymer. The method for producing the fibers comprises dispersing the spherical light absorbing and thermal energy storing and far infrared emitting iron oxide-based ceramics in the fiber-forming organic polymer or a solution containing the organic polymer and then spin the resultant mixture or solution. The resultant fibers are capable of efficiently generating heat, radiating far infrared rays and promoting the self-heat generation of a human body wearing the fibers and useful for exothermic and heat insulating uses, such as clothes, buildings and beddings.

Still, there is a need in the art to provide an improved radiative cooling structure that is scalable and capable of achieving day-time radiative cooling.

SUMMARY

It is one of the main objects of the present invention to achieve day-time radiative cooling.

It is another object of the present invention to provide an improved radiative cooling structure that is scalable and capable of achieving day-time radiative cooling.

It is another object of the present invention to optimize and practical adaptation of a Radi-cool-like glass-polymer hybrid metamaterial in the field of construction material, outdoor equipment, and automotive industry.

In order to overcome the limitations here stated, the present invention provides a radiative cooling structure for achieving day-time radiative cooling. The radiative cooling structure includes reflective layers sandwiching an emissive layer. The emissive layer includes a polymer. The emissive layer includes non-polymer particles arranged or distributed in a matrix or non-matrix fashion. The reflective layers reflect solar light, and the emissive layer having the non-polymer particles transmits solar radiation and emits infrared radiation. The radiative cooling structure releases the heat in the form of thermal radiation and lowers or maintains the temperature of an object or surface the radiative cooling structure is in thermal contact with.

In one example, the radiative cooling structure has a capability of emitting 5-13 micrometres (μm) of Infrared (IR) emission in an atmospheric window. The radiative cooling structure presents a performance of approximately 700 to 2100 Jules/hr (J/hr) per meter square (m²) of material. The performance changes depending on the temperature exposed to the radiative cooling structure.

The radiative cooling structure presents practical optimization and application of Radi-cool is explored to provide an affordable, scalable, and reliable means of passive day-time radiative cooling. The radiative cooling structure dispenses heat at a rate of approximately 110 W per meter square compared to the metamaterial of Dr. Zhai et al, which shows a noontime radiative cooling power of 93 watts per square meter under direct sunshine. The presently disclosed radiative cooling structure allows an object to remain 10-12° Celsius (° C.) lower than the ambient temperature, and theoretically cool a home with 40-meter square of material applied. While retaining the randomized micrometre-sized glass sphere (SiO₂) structure that supports strong IR emission and consequently effective radiative cooling, flexibility is practiced regarding the polymer framework housing the glass sphere structure to make it sufficiently durable, water resistant, and possibly wearable.

In one advantageous feature of the present invention, the radiative cooling structure can be used in thermal contact with solar panels, roofs, ceilings, and windows for cooling. Further, the radiative cooling structure can be used with heat exchange systems by placing the radiative cooling structure in thermal contact with heat exchanging media such as a heat exchanger or fluids.

In another advantageous feature of the present invention, the radiative cooling structure can come in one or more layers for applications where an object targeted for cooling benefits from reduced absorption of incident solar radiation.

Features and advantages of the invention hereof will become more apparent in light of the following detailed description of selected embodiments, as illustrated in the accompanying FIGUREs. As will be realized, the invention disclosed is capable of modifications in various respects, all without departing from the scope of the invention. Accordingly, the drawings and the description are to be regarded as illustrative in nature.

BRIEF DESCRIPTION OF THE DRAWINGS

With the above and other related objects in view, the invention consists in the details of construction and combination of parts as will be more fully understood from the following description, when read in conjunction with the accompanying drawings in which:

FIG. 1 illustrates an environment of in which a radiative cooling structure implements, in accordance with one embodiment of the present invention;

FIG. 2 illustrates a schematic view of the radiative cooling structure, in accordance with one embodiment of the present invention;

FIG. 3 illustrates a rolled up feature of the radiative cooling structure, in accordance with one embodiment of the present invention;

FIG. 4 illustrates a three-dimensional (3-D) schematic of the radiative cooling structure;

FIG. 5 illustrates a cut-out schematic of the radiative cooling structure;

FIG. 6 illustrates a photonic design of a radiative cooler;

FIG. 7 illustrates a schematic of a polymer-based hybrid metamaterial with randomly distributed SiO₂ microsphere inclusions for large-scale radiative cooling;

FIG. 8 illustrates a normalized absorption cross sections of individual microspheres;

FIG. 9 illustrates an angular diagram for the scattering far-field irradiance; and

FIGS. 10 and 11 illustrate a spectroscopic response of the hybrid metamaterial.

DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

The following detailed description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments in which the presently disclosed invention may be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for providing a thorough understanding of the presently disclosed radiative cooling structure. However, it will be apparent to those skilled in the art that the presently disclosed invention may be practiced without these specific details. In some instances, well-known structures and devices are shown in functional or conceptual diagram form in order to avoid obscuring the concepts of the presently disclosed radiative cooling structure.

In the present specification, an embodiment showing a singular component should not be considered limiting. Rather, the invention preferably encompasses other embodiments including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, the applicant does not intend for any term in the specification to be ascribed an uncommon or special meaning unless explicitly set forth as such. Further, the present invention encompasses present and future known equivalents to the known components referred to herein by way of illustration.

Although the present invention provides a description of a radiative cooling structure, it is to be further understood that numerous changes may arise in the details of the embodiments of the radiative cooling structure. It is contemplated that all such changes and additional embodiments are within the spirit and true scope of this disclosure.

The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure.

The present invention discloses a radiative cooling structure for achieving day-time radiative cooling. The radiative cooling structure includes reflective layers sandwiching an emissive layer. The emissive layer includes a polymer. The emissive layer includes non-polymer particles arranged or distributed in a matrix or non-matrix fashion. The reflective layers reflect solar light, and the emissive layer having the non-polymer particles transmits solar radiation and emits infrared radiation. The radiative cooling structure releases the heat in the form of thermal radiation and lowers or maintains the temperature of an object or surface the radiative cooling structure is in contact with.

Various features and embodiments of a radiative cooling structure are explained in conjunction with the description of FIGS. 1-11.

Referring to FIG. 1, an environment 5 in which radiative cooling structure 10 implements, in accordance with one exemplary embodiment of the present invention. A person skilled in the art understands that FIG. 1 is provided to show radiative cooling structure 10 positioned over a house (roof) 11 for illustrative purpose. Other implementations such as implementing radiative cooling structure 10 with solar panels, ceilings, and windows are within the scope of the present invention.

FIG. 2 shows a schematic view of radiative cooling structure 10, in accordance with one exemplary embodiment of the present invention. As can be seen FIGS. 1 and 2, radiative cooling structure 10 comes in the form of a sheet. Optionally, radiative cooling structure 10 comes in the form of a film or coating. Radiative cooling structure 10 includes a first side 12 and a second side 14, as shown in FIG. 2. First side 12 indicates a top end and second side 14 indicates a bottom end. Radiative cooling structure 10 includes a first layer 16 and second side 14 includes a second layer 18. In one example, each of first layer 16 and second layer 18 includes a reflective layer. In another example, each of first layer 16 and second layer 18 includes a non-reflective layer. In yet another example, first layer 16 includes a reflective layer and second layer 18 includes a non-reflective layer, or vice versa. Each of first layer 16 and second layer 18 is made of glass. Optionally, each of first layer 16 and second layer 18 is made of a metal or any other suitable material. For example, each of first layer 16 and second layer 18 is made of aluminium, silver, gold, or copper. Each of first layer 16 and second layer 18 has a thickness of 20 nm to 1 μm depending on the cooling benefits needed. Further, first layer 16 and second layer 18 have the same thickness/size or are different from one another.

Radiative cooling structure 10 includes an emissive layer 20. Emissive layer 20 includes a polymer selected from a group of 4-methyl-1-pentene polymer, a 4-methyl-1-pentene copolymer, polyvinyl fluoride, and polyethylene terephthalate. In one example, emissive layer 20 comes in the form of a sheet. The thickness of emissive layer 20 ranges from 10 μm to 3 or more millimeters depending on the need. As can be seen from FIG. 2, emissive layer 20 positions in between first layer 16 and second layer 18. As can be seen from FIG. 2, the thickness of emissive later 20 is more than the effective diameter of non-polymer particles 22. Emissive layer 20 includes non-polymer particles 22. Non-polymer particles 22 are arranged/distributed in a matrix or non-matrix fashion in emissive layer 20. In one implementation, non-polymer particles 22 are distributed in the same direction. The repetitive distribution of non-polymer particles 22 at a distance from one another allows to control the wavelength through which the energy can be controlled. Non-polymer particles 22 come in spherical, ellipsoidal, polyhedral, rod-shaped, plate-shaped or irregular shape. In one example, non-polymer particles 22 are of a dielectric material. Non-polymer particles 22 are made of materials such as silicon dioxide (SiO2), calcium carbonate (CaCO3), titanium dioxide (TiO2), silicon carbide (SiC), zinc oxide (ZnO), alumina (Al2O3) or any type of glass-like materials, and combination thereof. Non-polymer particles 22 have a volume percentage ranging from 2% to 25% and with an average size ranging from 3 μm to 30 μm.

In accordance with the present invention, emissive layer 20 and non-polymer particles 22 have absorption bands in an “atmospheric window” or “atmospheric transparent window”. The atmospheric window indicates a region of the electromagnetic spectrum that can pass through the atmosphere of Earth. In use, each of first layer 16 and second layer 18, when come in contact with the solar light, reflect the solar light. Consider, first layer 16 is facing the Sun. Here, first layer 16 receives and reflects the solar light. Further, emissive layer 20 transmits solar radiation and emits infrared radiation. In one example, emissive layer 20 has absorption bands in the atmospheric transmission window and do not exhibit absorption in the solar spectrum from 0.3 to 3 μm. Non-polymer particles 22 within emissive layer 20 further enhances the performance of emissive layer 20 by increasing infrared emissivity and added absorption resonances. In one example, the non-polymer particles 22 have absorption bands in an atmospheric window and does not show significant absorption in the solar spectrum from 0.3 to 3 μm. The size and arrangement of non-polymer particles 22 can be changed to decrease solar absorption and increase thermal efficiency. Subsequently, second layer 18 transmits solar radiation at a much reduced temperature than solar radiation received at first layer 16.

Radiative cooling structure 10 is capable of dispensing heat at the rate of approximately 110 W per meter square, and allows an object to remain 10-12° C. lower than the ambient temperature. Radiative cooling structure 10 retains the randomized micrometre-sized glass sphere (SiO₂) structure that supports strong IR emission and consequently effective radiative cooling.

Radiative cooling structure 10 can be produced via Roll to Roll Manufacturing (R2R, also known as web path, reel to reel, etc.). Radiative cooling structure 10 can be manufactured in a roll, as shown in FIG. 3, for example. R2R manufacturing allows cost-effective continuous production of radiative cooling structure 10. In R2R manufacturing, a roll of material is introduced to a streamline and another layer (loose material or another roll of material) is applied to/fused with the starting roll, effectively generating an output roll. Optionally, radiative cooling structure 10 can be produced by stacking layers on top of each other sequentially in a R2R production line. Both polymer framework layers can be introduced as a roll of material, and the rest can be coated/sprayed/printed on top of them starting as loose material.

The radiative cooling structure 10 is adapted for passive day-time radiative cooling. The radiative cooling structure 10 dispenses heat at a rate of approximately 110 W per meter square, allow an object to remain 10-12° C. lower than the ambient temperature, and theoretically cool a home with 40-meter square of material applied. The radiative cooling structure 10 retains the randomized micrometre-sized glass sphere (SiO₂) structure that supports strong IR emission and consequently effective radiative cooling. Further, flexibility is achieved using the polymer framework housing the glass sphere structure to make it sufficiently durable, water resistant, and possibly wearable.

FIG. 4 shows a three-dimensional (3-D) schematic 100 of radiative cooling structure 102, in accordance with one embodiment of the present invention. Radiative cooling structure 102 rests over a roof 104 at an angle i.e., in a slant or tapered configuration. As can be seen in FIG. 4, radiative cooling structure 102 reflects sunlight 106 and selectively emits thermal radiation 108. By reflecting sunlight 106 and selectively emitting thermal radiation 108, radiative cooling structure 102 reduces both convection and conduction to the radiative cooler 110 under peak solar irradiance.

FIG. 5 shows cut-out schematic of a radiative cooling structure 200 (through middle), in accordance with one embodiment of the present invention. Radiative cooling structure 200 includes an aluminized Mylar 202, a low-density polyethylene 204, a photonic radiative cooler 206, a clear acrylic 208, an air pocket 210, an aluminized Mylar 212, and a polystyrene Mylar 214. As can be seen, radiative cooling structure 200 shows air pocket 210 created around photonic radiative cooler 206. In other words, photonic radiative cooler 206 is suspended in a relatively well sealed air pocket 210. Such air pocket 210 positioning represents a key part of daytime radiative cooling. The presently disclosed design aims to ensure that any surface in immediate contact with air pocket 210 heats up minimally due to solar irradiance.

FIG. 6 shows a photonic design 300 of the radiative cooler, in accordance with one exemplary embodiment of the present invention. The photonic radiative cooler consists of seven alternating layers of hafnium dioxide (HfO₂) and silicon dioxide (SiO₂) of varying thicknesses, on top of 200 nm of silver (Ag). The seven alternating layers are deposited on top of a 200-mm silicon wafer. The bottom four layers of HfO₂, and SiO₂, have thicknesses that are less than 100 nm and assist in optimizing solar reflection.

The HfO₂ serves as a high-index material that presents low ultraviolet absorption when optimizing for solar reflectance, while SiO₂ is optically transparent and is the low-index layer. The use of HfO₂ is not particularly needed. In one alternate embodiment, HfO₂ is replaced with titanium dioxide (TiO₂). As can be seen from FIG. 6, the top three layers are much thicker. The top three layers are responsible for thermal radiation from the cooler, through a combination of material properties and interference effects. SiO₂ has a strong peak in its absorptivity near 9 μm due to its phonon-polariton resonance. HfO₂ presents a non-zero absorption and hence emission in the 8-13 μm wavelength range. In accordance with the present embodiment, the HfO₂ presents the non-zero absorption and emission in the 9-15 μm wavelength range to dispense the heat at the rate of approximately 110 W per meter square. The combination of all the layers results in a macroscopically planar and integrated structure that collectively achieve a high solar reflectance and strong thermal emission.

FIG. 7 shows a radiative cooling with a randomized, glass polymer hybrid metamaterial 400, in accordance with one embodiment of the present invention. The randomized, glass polymer hybrid metamaterial 400 includes the polymer-based hybrid metamaterial with randomly distributed SiO₂ microsphere inclusions for large-scale radiative cooling. The microspheres interact strongly with the infrared light. Further, the microspheres make the metamaterial extremely emissive across the full atmospheric transmission window while remaining transparent to the solar spectrum. Metamaterial 400 consists of a visibly transparent polymer encapsulating randomly distributed silicon dioxide (SiO₂) microspheres. The spectroscopic response spans two orders of magnitude in wavelength (0.3 to 25 μm). The presently disclosed metamaterial 400 is extremely emissive across the entire atmospheric transmission window (9 to 15 μm). This is due to the phonon enhanced Fröhlich resonances of the microspheres. In one example, a 50 μm thick metamaterial film containing 6% of microspheres by volume presents an infrared emissivity of about 0.93 and reflects about 95% of solar irradiance when backed with a 200-nm thick silver coating. As shown in FIG. 7, the proposed randomized, glass polymer hybrid metamaterial 400 includes the polymer-based hybrid metamaterial with randomly distributed SiO₂ microsphere inclusions for large-scale radiative cooling.

The polymer matrix material and the encapsulated SiO₂ microspheres are lossless in the solar spectrum. As a result, the absorption is nearly absent, and direct solar irradiance does not heat metamaterial 400. The encapsulated SiO₂ microspheres have optical properties different from the surrounding matrix at infrared wavelengths. This is due to the existence of strong phonon-polariton resonances at about 10 μm. FIG. 8 shows a normalized absorption (blue), scattering (red), and extinction (black) cross sections of individual microspheres as functions of size parameter (koa). As can be seen from FIG. 8, the sum of the scattering and absorption peaks at a size parameter of 2.5, which corresponds to a microsphere radius of 4 μm. Further, the electric field distributions of two microspheres with 1 and 8 μm diameters, illuminated at a 10 μm wavelength. As can be noted, the smaller microsphere resonates at the electric dipolar resonance, whereas higher-order electric and magnetic modes are excited in the larger microsphere. At the peak, the high-order Fröhlich resonances (i.e., both electric and magnetic modes) are strongly excited as can be seen by the strong forward scattering in FIG. 9. FIG. 9 shows an angular diagram 600 for the scattering far-field irradiance of an 8 μm diameter microsphere with 10-11 μm wavelength illumination. The incident field is polarized along the y direction and propagating along the z direction.

FIGS. 10 and 11 show spectroscopic response of the hybrid metamaterial, in accordance with one exemplary embodiment of the present invention. Specifically, FIG. 10 shows a schematic diagram of a hybrid metamaterial 700 backed with a thin silver film 702. Silver film 702 diffusively reflects most of the incident solar irradiance 704, whereas the hybrid material absorbs all incident infrared irradiance 706 and is highly infrared emissive. Hybrid metamaterial 700 strongly reflects solar irradiation when backed with a 200 nm thick silver thin film prepared by means of electron beam evaporation. FIG. 11 shows three-dimensional (3D) confocal microscope image of the hybrid metamaterial 800. The microspheres are visible because of the auto fluorescence of SiO₂. The integrated spheres account for scattered light from in spectral regions. As specified above, 50 μm thick metamaterial film containing 6% of microspheres by volume presents an infrared emissivity of about 0.93 and reflects about 95% of solar irradiance when backed with a 200-nm thick silver coating.

The presently disclosed radiative cooling structure can be used for a variety of day-time radiative cooling applications. For example, radiative cooling structure can be used as a construction material. As known, a roofing underlayment is used as a layer of sheeting material applied between a building's roof and shingles. Here, the pre-existing roofing underlayment products serve as a moisture barrier and a stable layer for shingle installation. This provides an ergonomic working platform for the workers and further weather protection. The adoption of radiative cooling structure helps to cool the house, reduce energy consumption on air-conditioning, and create more sustainable communities. Optionally, radiative cooling structure can be used by applying adhesive coating on the side facing the roof, printing anti-slip material on the side facing the shingles, and possibly replacing the polymer framework with more durable material or woven pattern. In addition, the radiative cooling structure can be configured for achieving day-time radiative cooling in the form of fibre or fluffy/flat fitting material, which can be used for exothermic and heat insulating uses. For example, the radiative cooling structure can be provided in the form of fabric/cloth, building material and bedding material. Alternatively, the radiative cooling structure can be provided in the form of a non-woven fabric such as facial mask fabrics, and medical non-woven fabrics, for example. Further, the radiative cooling structure can be applied in surface coating applications or fabric infusion depending on the need. Furthermore, the radiative cooling structure can be integrated in Morphis for making paint and the like. For example, the radiative cooling structure can be used as paint for a vehicle such as car. In one example, the radiative cooling structure is used in medical devices in the form of ceramic material based devices.

Additionally, radiative cooling structure can be applied as a layer to pre-existing shingles and an add-on passive cooling perk can be achieved swiftly.

Further, radiative cooling structure can be used in outdoor equipment. In one example, radiative cooling structure can be used as a tent material to control interior temperature of the tent. Here, emissive layer i.e., the polymer is reinforced or combined with other robust sheeting material to protect the occupants in the tent in a hot environment.

Further, radiative cooling structure can be used in the vehicle industry as a cooling lining for automobiles. Radiative cooling structure can lower the energy/fuel consumption rate of automobiles in hot regions.

Furthermore, radiative cooling structure can be used as a cold chain supplement for passive cooling. Here, radiative cooling structure can be wrapped over products to reduce the temperature of the product.

Based on the above, it is evident that the presently disclosed radiative cooling structure (or radiative cooling glass-polymer hybrid metamaterial) can be used in a variety of commercial applications including, but not limited to, roofing underlayment, roofing shingles, tents, cooling liners for automobiles, and cold chain. Accordingly, the present invention enables and provides a product and/or process that helps mitigate climate change by being designed to: (a) further support removal greenhouse gases already present in the atmosphere; (b) reduce and/or prevent additional greenhouse gas emissions; and/or (c) monitor, track, and/or verify greenhouse gas emission reductions by being able to readily apply building structures and effect a different climate effects of specific construction.

In the above description, numerous specific details are set forth such as examples of some embodiments, specific components, devices, methods, in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to a person of ordinary skill in the art that these specific details need not be employed, and should not be construed to limit the scope of the invention.

In the development of any actual implementation, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints. Such a development effort might be complex and time-consuming, but may nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill. Hence as various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

The foregoing description of embodiments is provided to enable any person skilled in the art to make and use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the novel principles and invention disclosed herein may be applied to other embodiments without the use of the innovative faculty. It is contemplated that additional embodiments are within the spirit and true scope of the disclosed invention.

Claims

1. A radiative cooling structure for achieving day-time radiative cooling, said radiative cooling structure comprising: reflective layers; andan emissive layer, wherein said emissive layer sandwiches between said reflective layers,wherein said reflective layers reflect solar light, and said emissive layer transmits solar radiation and emits infrared radiation, and wherein said radiative cooling structure releases the heat in the form of thermal radiation and lowers or maintains the temperature of an object or surface said radiative cooling structure is in thermal contact with.

2. A radiative cooling structure for achieving day-time radiative cooling, said radiative cooling structure of claim 1, wherein said radiative cooling structure mitigates climate change by being designed to remove greenhouse gases already present in the atmosphere.

3. The radiative cooling structure of claim 1, wherein said emissive layer comprises a polymer, and said reflective layers are made of a glass or metal or ceramic.

4. The radiative cooling structure of claim 1, wherein said emissive layer comprises non-polymer particles arranged or distributed in a matrix or non-matrix fashion.

5. The radiative cooling structure of claim 1, wherein said emissive layer and said non-polymer particles comprise absorption bands in an atmospheric window and do not exhibit absorption in the solar spectrum from 0.3 micrometres (μm) to 3 μm.

6. The radiative cooling structure of claim 1, wherein said each of said reflective layers has a thickness of 20 nanometres (nm) to 1 micrometre (μm).

7. The radiative cooling structure of claim 3, wherein said non-polymer particles come in spherical, ellipsoidal, polyhedral, rod-shaped, plate-shaped or irregular shape.

8. The radiative cooling structure of claim 3, wherein said non-polymer particles are made of silicon dioxide (SiO2), calcium carbonate (CaCO3), titanium dioxide (TiO2), silicon carbide (SIC), zinc oxide (ZnO), alumina (Al2O3), and combination thereof.

9. The radiative cooling structure of claim 3, wherein said non-polymer particles have a volume percentage ranging from 2% to 25% with an average size ranging from 3 micrometres (μm) to 30 μm.

10. The radiative cooling structure of claim 1, wherein said radiative cooling structure comes in the form of a film, coating, a fabric, or a non-woven fabric.

11. The radiative cooling structure of claim 1, wherein said emissive layer comprises a polymer selected from a group of 4-methyl-1-pentene polymer, a 4-methyl-1-pentene copolymer, polyvinyl fluoride, and polyethylene terephthalate.

12. The radiative cooling structure of claim 1, wherein said emissive layer has a thickness ranging from 10 micrometres (μm) to 3 millimetres (mm).

13. The radiative cooling structure of claim 1, wherein said radiative cooling structure emits 5-13 micrometres (μm) Infrared (IR) emission in an atmospheric window.

14. The radiative cooling structure of claim 1, wherein said radiative cooling structure dispenses heat at an approximately 110 Watt per meter square, and allows said object or surface to remain 10-12° Celsius (° C.) lower than the ambient temperature.

15. The radiative cooling structure of claim 1, wherein said radiative cooling structure retains a randomized micrometre-sized glass sphere Silicon Dioxide (SiO2) structure that supports Infrared (IR) emission and consequently effective radiative cooling.

16. The radiative cooling structure of claim 1, wherein said radiative cooling structure comprises a randomized, glass polymer hybrid metamaterial having a randomly distributed Silicon Dioxide (SiO2) microsphere inclusions for large-scale radiative cooling.

17. A radiative cooling structure for achieving day-time radiative cooling, said radiative cooling structure comprising: a first layer and a second layer, wherein each of said first layer and said second layer comprises a reflective layer or a non-reflective layer; andan emissive layer, wherein said emissive layer comprises a polymer, and wherein said emissive layer sandwiches between said first layer and said second layer,wherein said first layer and said second layer reflect solar light, and said emissive layer transmits solar radiation and emits infrared radiation, and wherein said radiative cooling structure releases the heat in the form of thermal radiation and lowers or maintains the temperature of an object or surface said radiative cooling structure is in thermal contact with.

18. The radiative cooling structure of claim 16, wherein said emissive layer comprises non-polymer particles arranged or distributed in a matrix or non-matrix fashion.

19. The radiative cooling structure of claim 16, wherein said emissive layer and said non-polymer particles comprise absorption bands in an atmospheric window and do not exhibit absorption in the solar spectrum from 0.3 micrometres (μm) to 3 μm.

20. A method of providing a radiative cooling structure for achieving day-time radiative cooling, said method comprising the steps of: providing reflective layers;providing an emissive layer;sandwiching said emissive layer between said reflective layers such that said reflective layers reflect solar light, and said emissive layer transmits solar radiation and emits infrared radiation; andreleasing heat in the form of thermal radiation and lowering or maintaining the temperature of an object or surface said radiative cooling structure is in thermal contact with.