Thermal diode, glass curtain wall and application thereof

Abstract

The invention discloses a thermal diode, a glass curtain wall and application thereof. The thermal diode comprises at least one working unit, and the working unit comprises an evaporation end provided with a heat transfer medium adsorption layer which comprises polymer ethanol gel; the condensation end is located on the side, away from the evaporation end, of the working unit; the heat barrier layer is positioned between the evaporation end and the condensation end; the heat transfer medium is located at the evaporation end, at least part of the heat transfer medium is adsorbed in the heat transfer medium adsorption layer, and the heat transfer medium comprises ethyl alcohol. Polymer ethanol gel is used as an interface evaporation material, has very high ethanol affinity, can quickly absorb and transmit a heat-transfer medium ethanol, provides material supplement for evaporation of the heat-transfer medium ethanol, and accelerates heat transfer; the heat transfer performance is improved through interface evaporation instead of conventional body evaporation. Finally, the overall structure is simpler, the heat transfer efficiency is higher, and the vertical glass curtain wall can be applied.

Description

Technical Field

[0001] The present application relates to the technical field of thermal management materials, and in particular to a thermal diode, a glass curtain wall and applications thereof. Background Art

[0002] Heat pipes are currently a commonly used heat transfer element in many heat dissipation fields. They include an evaporation section that contacts high temperatures, a condensation section that contacts low temperatures, and a heat transfer medium that moves between the evaporation section and the condensation section. Common heat pipes include gravity heat pipes, pulsating heat pipes, flat heat pipes, rotating heat pipes, loop heat pipes, thermal diodes, and many other types. Similar to an electrical diode, a thermal diode is a heat pipe that only allows heat to flow in one direction and does not allow it to flow in the opposite direction. In this way, the thermal diode achieves high heat transfer in one direction and heat blocking in the opposite direction.

[0003] Currently, effective thermal diode technologies include phase-change thermal diodes, which efficiently transfer heat through the evaporation and condensation of water in the heat transfer direction, and block heat transfer through air in the opposite direction. Specifically, it includes a hydrophilic side and a hydrophobic side, separated by an air layer. When the temperature on the hydrophilic side is higher, water evaporates on the hydrophilic side to absorb heat and condenses on the hydrophobic side to release heat, and automatically falls back to the hydrophilic side through the gravity effect, forming a cycle and continuously transferring heat; and when the temperature on the hydrophobic side is higher than the hydrophilic side, the air layer effectively blocks the heat transfer. As a result, the phase-change thermal diode exhibits different heat transfer performance in two directions.

[0004] However, the heat transfer medium used by this type of thermal diode is mainly water, which makes it difficult to achieve efficient heat transfer. The usual solution is to evacuate the heat, but evacuating the heat will place high demands on the pressure resistance of the thermal diode and increase the construction and maintenance costs of the equipment. In addition, the circulation of water requires the help of gravity, so most thermal diodes are horizontal; or they rely on other external forces (such as pumps, electric fields) to maintain their height, which greatly increases the cost and structural complexity, making it difficult for thermal diodes to be applied to vertical glass curtain walls. For this reason, it is necessary to develop a thermal diode with a simple structure, high heat transfer efficiency, and suitable for vertical glass curtain walls. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a thermal diode, a glass curtain wall and applications thereof.

[0006] In a first aspect of the present application, a thermal diode is provided, the thermal diode comprising at least one working unit, the working unit comprising:

[0007] The evaporation end is provided with a heat transfer medium adsorption layer, and the heat transfer medium adsorption layer includes a polymer ethanol gel;

[0008] The condensation end is located on the side of the working unit away from the evaporation end;

[0009] A heat barrier layer, which is located between the evaporation end and the condensation end;

[0010] The heat transfer medium is located at the evaporation end and is at least partially adsorbed in the heat transfer medium adsorption layer. The heat transfer medium includes ethanol.

[0011] The thermal diode according to the embodiment of the present application has at least the following beneficial effects:

[0012] The polymer ethanol gel is used as the interface evaporation material. It has a high affinity for ethanol and can quickly absorb and transfer the heat transfer medium ethanol, providing material supplement for its evaporation and accelerating heat migration. The interface evaporation of ethanol in the polymer ethanol gel rather than the conventional bulk evaporation also brings about an improvement in heat transfer performance. At the same time, due to the low boiling point and high volatility of ethanol, the thermal diode can spontaneously absorb heat from the evaporation end and release it to the condensation end to achieve efficient and long-lasting heat transfer. Moreover, ethanol has an extremely low boiling point and can be used normally at lower temperatures without failing due to solidification. In addition, the heat transfer medium adsorption layer can absorb ethanol and maintain it at a certain height through capillary action without the need for additional pumps or electric fields, which removes the limitation of the horizontal placement of traditional phase-change thermal diodes and enables thermal diodes to be used in vertical glass curtain walls of building envelopes. In the end, the overall structure is simpler and the heat transfer efficiency is higher.

[0013] In some embodiments of the present application, the polymerized monomers for forming the polymer ethanol gel include at least one of acrylic acid, acrylamide, and vinyl pyrrolidone.

[0014] In some embodiments of the present application, the polymer ethanol gel comprises polyacrylic acid ethanol gel.

[0015] In some embodiments of the present application, the raw materials for preparing the polymer ethanol gel include polymerization monomers, a cross-linking agent, an initiator and ethanol.

[0016] In some embodiments of the present application, the initiator includes at least one of sodium persulfate, potassium persulfate, ammonium persulfate, 2,2'-azobisisopropylimidazoline hydrochloride, 2,2'-azo(2-methyl-N-(2-hydroxyethyl)propionamide) and 2,2-azabis(2-imidazoline) dihydrochloride.

[0017] In some embodiments of the present application, the cross-linking agent includes at least one of formaldehyde, glutaraldehyde, genipin, ethylene glycol diglycidyl ether, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate and pentaerythritol triallyl ether.

[0018] In some embodiments of the present application, the bottom of the evaporation end is lower than the bottom of the condensation end.

[0019] In some embodiments of the present application, the ratio of the thickness of the heat transfer medium adsorption layer to the distance between the heat transfer medium adsorption layer and the condensation end is 1:0.1-10.

[0020] In a second aspect of the present application, a method for preparing the aforementioned thermal diode is provided, the method comprising synthesizing a polymer ethanol gel:

[0021] Mixing a polymerizable monomer, a cross-linking agent, an initiator and water to form a polymer hydrogel through a cross-linking reaction;

[0022] The polymer hydrogel is mixed with ethanol and replaced to generate a polymer ethanol gel.

[0023] A third aspect of the present application provides a glass curtain wall, comprising any one of the aforementioned thermal diodes.

[0024] In some embodiments of the present application, the angle between the glass curtain wall and the horizontal plane during assembly is greater than 30°.

[0025] A fourth aspect of the present application provides application of the aforementioned thermal diode or the aforementioned glass curtain wall in the field of thermal management.

[0026] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of a thermal diode in the prior art.

[0028] Figure 2 Schematic diagram of the structure of a working unit of a thermal diode in one embodiment of the present application.

[0029] Figure 3 It is a structural schematic diagram of a working unit of a thermal diode in another embodiment of the present application.

[0030] Figure 4 This is the test result of the light transmittance of polyacrylic acid ethanol gel in one embodiment of the present application.

[0031] Figure 5 is an engineering drawing of an array of thermal diodes in one embodiment of the present application.

[0032] Figure 6 Schematic diagram of a working unit of a thermal diode used for testing in one embodiment of the present application.

[0033] Figure 7 The figure is a comparison of the evaporation rates of bulk evaporation of ethanol and interfacial evaporation using polyacrylic acid ethanol gel in an embodiment of the present application.

[0034] Reference numerals: working unit 100 , evaporation end 110 , heat transfer medium adsorption layer 111 , condensation end 120 , heat barrier layer 130 , heat transfer medium 200 , partition 300 , evaporation chamber 310 , condensation chamber 320 . DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the concept of the present application and the technical effects produced in combination with the embodiments, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of them. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present application.

[0036] The embodiments of the present application are described in detail below. The described embodiments are exemplary and are only used to explain the present application, and should not be understood as limiting the present application.

[0037] In the description of this application, "several" means more than one, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0038] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0039] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0040] refer to Figure 1, shows the basic structure of a thermal diode, including a working unit 100, which includes an evaporation end 110 and a condensation end 120 arranged opposite to each other. A heat transfer medium 200, usually water, is also provided in the working unit 100. The principle of the thermal diode is that when the temperature near the evaporation end 110 is high and the temperature near the condensation end 120 is low, the heat transfer medium 200 located at the evaporation end 110 is heated and evaporated into a gaseous state, as shown by the dotted arrow in the figure, taking away the heat and moving to the condensation end 120 and re-liquefying into a liquid state when it encounters cold. Thereafter, the heat transfer medium 200 that liquefies the condensation end 120 returns to the evaporation end 110 to complete the cycle. At the same time, a thermal barrier layer 130 is provided between the evaporation end 110 and the condensation end 120. When the temperature near the evaporation end 110 is low and the temperature near the condensation end 120 is high, the presence of the thermal barrier layer 130 effectively isolates the condensation end 120 from transferring heat to the evaporation end 110. For the circulation of the heat transfer medium 200, the conventional thermal diode method includes but is not limited to setting the evaporation end 110 and the condensation end 120 to be horizontal, and the evaporation end 110 is located at the lower part of the gravity direction compared to the condensation end 120, so that the heat transfer medium 200 liquefied at the condensation end 120 will drip from the condensation end 120 back to the evaporation end 110 under the action of gravity, realizing circulation and continuously transferring heat. The thermal diode therefore exhibits different heat transfer performance in two directions. However, this horizontal thermal diode is difficult to apply to the vertical glass curtain wall, and the heat transfer efficiency of the thermal diode also needs to be improved. For this reason, this application is specially proposed.

[0041] refer to Figure 2 , shows the structure of a thermal diode in an embodiment of the present application, the thermal diode includes at least one working unit 100, and the working unit 100 has an evaporation end 110 and a condensation end 120 arranged opposite to each other. A heat transfer medium 200 is also provided in the working unit 100. Unlike conventional thermal diodes that use water as a heat transfer medium, the heat transfer medium 200 in the working unit 100 of the thermal diode in the embodiment of the present application includes ethanol. The evaporation performance of water at room temperature is relatively weak, and it is difficult to achieve high-performance heat transfer through a rapid evaporation-condensation process. The heat transfer medium ethanol used in the embodiment of the present application has high volatility at room temperature, so that the thermal diode can use environmental energy to spontaneously evaporate and absorb heat at the evaporation end and condense and release heat at the condensation end without the need for additional energy input.

[0042] In addition, in the thermal diode in one embodiment of the present application, the working unit 100 additionally introduces a heat transfer medium adsorption layer 111 disposed at the evaporation end 110, and the heat transfer medium adsorption layer 111 includes a polymer ethanol gel. Compared with the traditional method of using water as a heat transfer medium for bulk evaporation, the embodiment of the present application uses a polymer ethanol gel for interfacial evaporation of ethanol. The polymer ethanol gel has a high affinity for ethanol and can provide material supplement for the evaporation of ethanol by rapidly absorbing and transmitting ethanol.

[0043] In some embodiments, the polymer ethanol gel also has a loose porous structure, which can effectively increase the evaporation area and achieve excellent ethanol interface evaporation performance. The loose porous structure is usually composed of a polymer network, and the types of pores include but are not limited to at least one of micropores (pore size less than 2nm), mesopores (pore size between 2 and 50nm), and macropores (pore size greater than 50nm).

[0044] Due to the setting of the heat transfer medium adsorption layer 111 and the change of the heat transfer medium 200, the thermal diode eliminates the need for vacuuming and the restriction on the freezing point, the actual application performance is enhanced, high-performance interface evaporation is achieved, the heat transfer performance is improved, and it can be applied on vertical glass curtain walls.

[0045] In some embodiments, reference Figure 3 , the bottom of the evaporation end 110 is lower than the bottom of the condensation end 120. By means of the structural arrangement in this way, the bottom of the evaporation end 110 and the bottom of the condensation end 120 have a certain height difference, and the ethanol condensed on the condensation end 120 will continue to move downward (in the direction shown by the dotted line in the figure) under the action of gravity and flow back to the evaporation end 110, thereby quickly completing the circulation of the ethanol. In addition, it is also possible to avoid the ethanol from staying at the condensation end, so that when the temperature of the condensation end 120 is high, the ethanol staying at the condensation end 120 evaporates and dissipates heat to improve the reverse heat transfer efficiency.

[0046] In some embodiments, the condensation end 120 is connected to the evaporation end 110 through an inclined surface extending downward along the gravity direction from the condensation end 120 toward the evaporation end 110. The condensed ethanol continues to move downward at the bottom of the condensation end 120 through the inclined surface and flows back to the evaporation end 110.

[0047] The heat transfer mechanism of the thermal diode provided in the embodiment of the present application is further analyzed as follows:

[0048] The heat transfer medium adsorption layer 111 has good affinity for ethanol, so the heat transfer medium adsorption layer 111 located at the evaporation end 110 will spontaneously absorb the heat transfer medium 200 ethanol in the working unit 100 through capillary action, especially the heat transfer medium 200 ethanol located at the bottom of the working unit 100 along the gravity direction, and maintain a certain height of ethanol in the heat transfer medium adsorption layer 111. In this case, referring to the dotted line direction in the figure, when the temperature of the evaporation end 110 is higher than that of the condensation end 120, the heat transfer medium 200 ethanol adsorbed in the heat transfer medium adsorption layer 111 is heated and evaporated therefrom. Due to the concentration difference of ethanol vapor between the evaporation end 110 and the condensation end 120, the strong volatility of ethanol, and the distance between the two ends, the evaporated ethanol vapor can quickly reach the condensation end 120 (mainly the top) to release heat and condense, and then slide to the bottom of the condensation end 120 and be absorbed by the heat transfer medium adsorption layer 111 again, forming a cycle. Thus, the heat transfer from the evaporation end 110 to the condensation end 120 can be continuously performed by the evaporation-condensation process of ethanol. When the temperature of the condensation end 120 is higher than the temperature of the evaporation end 110, due to the lack of heat transfer medium 220 on the condensation end 120 and the presence of the thermal barrier layer 130 between the evaporation end 110 and the condensation end 120, the heat transfer coefficient is greatly reduced, thereby achieving the effect of heat preservation and heat insulation.

[0049] In addition, due to the strong volatility of ethanol at room temperature, even if there is no obvious temperature difference between the evaporation end 110 and the condensation end 120, ethanol will spontaneously evaporate from the evaporation end 110 to absorb heat and condense at the condensation end 120 to release heat, thereby achieving continuous spontaneous heat transfer without energy consumption.

[0050] Therefore, the temperature regulation can be achieved by using the thermal diode provided in the embodiment of the present application, as follows:

[0051] In winter, the evaporation end 110 is set to face the outdoors and the condensation end 120 is set to face the indoors. During the day, the working unit 100 of the thermal diode can use the heat of sunlight (polymer ethanol gel can transmit visible light and absorb infrared light) and the heat of the external environment to provide passive heating for the indoors and keep the indoors warm at night; in summer, the evaporation end 110 is set to face the indoors and the condensation end 120 is set to face the outdoors. During the day, the working unit 100 of the thermal diode can insulate the high outdoor temperature and dissipate the indoor heat through evaporation-condensation at night to achieve passive cooling. In addition, the continuous spontaneous heat transfer performance brought about by the high volatility of ethanol at room temperature can also make the passive heating in winter and the passive cooling in summer better.

[0052] In some embodiments, the polymer in the polymer ethanol gel comprises at least one of a natural polymer and a synthetic polymer. In some embodiments, the polymer ethanol gel comprises at least one of a cationic gel, an anionic gel and a neutral gel according to ionic charge.

[0053] In some embodiments, the polymerizable monomers for forming the polymer ethanol gel include at least one of acrylic acid, acrylamide, and vinyl pyrrolidone.

[0054] In some embodiments, the polymer in the polymer ethanol gel is at least one of a homopolymer and a copolymer (including but not limited to a block copolymer, a graft copolymer, and a random copolymer).

[0055] In some embodiments, the polymer in the polymer ethanol gel is at least one of polyacrylic acid, polyacrylamide, polyvinyl pyrrolidone or a copolymer of at least two monomers of acrylic acid, acrylamide and vinyl pyrrolidone.

[0056] It is understood that other monomers known in the art that can be used as polymers in polymer ethanol gel can also be used as partial or complete substitutes for the above monomers, including but not limited to methacrylic acid, methacrylate, acrylate (such as sodium acrylate), dimethyl acrylamide, isopropyl acrylamide. In addition, the polymer ethanol gel can also include other polymers that can form hydrogels alone or mixed with other polymers and form ethanol gels through replacement, including but not limited to polylactic acid, polyethylene oxide, polyvinyl alcohol, polyesters (such as poly (2-hydroxyethyl methacrylate), polycaprolactone, polyphosphazene), polyanhydride, cellulose, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, starch, gum, chitin, chitosan, dextran, alginate, carrageenan, pectin, lignin, laminin, collagen, gelatin, proteoglycan, elastin, silk protein, globular protein, etc. At least one of them.

[0057] In some embodiments, the polymer ethanol gel comprises polyacrylic acid ethanol gel.

[0058] In some embodiments, the polymer ethanol gel is formed by cross-linking polymers, and the cross-linking method includes at least one of physical cross-linking (including but not limited to cross-linking by hydrogen bonding, ionic force, van der Waals interaction, polyelectrolyte complexation, stereocomplexation and hydrophobic force), chemical cross-linking. Specifically, it includes but is not limited to at least one of simple mixing, solution casting, bulk polymerization, free radical polymerization, ultraviolet or gamma irradiation, interpenetrating network and the like.

[0059] In some embodiments, the polymer ethanol gel is prepared by chemical cross-linking.

[0060] In some embodiments, the raw materials for preparing the polymer ethanol gel include polymerization monomers, a cross-linking agent, an initiator and ethanol.

[0061] In some embodiments, the initiator includes at least one of persulfates (including but not limited to sodium persulfate, potassium persulfate, ammonium persulfate), azo (including but not limited to 2,2'-azobisisobutyronitrile, 2,2'-azobisisovaleronitrile, 2,2'-azobisisoheptanenitrile, 2,2'-azobisisopropylimidazoline hydrochloride, 2,2'-azo(2-methyl-N-(2-hydroxyethyl)propionamide)) and 2,2-azabis(2-imidazole) dihydrochloride.

[0062] In some embodiments, the crosslinking agent includes at least one of formaldehyde, glutaraldehyde, genipin, ethylene glycol diglycidyl ether, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, and pentaerythritol triallyl ether.

[0063] In some embodiments, reference Figure 2 The ratio of the thickness w of the heat transfer medium adsorption layer to the distance l between the heat transfer medium adsorption layer and the condensation end is 1:0.1-10. For example, w:l can be 1:0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0064] In some embodiments, the thickness w of the heat transfer medium adsorption layer is 1 to 50 mm, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, or 50 mm.

[0065] In some embodiments, the distance l between the heat transfer medium adsorption layer and the condensation end is 0.1 to 500 mm, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 100, 200, 300, 400, or 500 mm.

[0066] In some embodiments, the thermal diode includes a plurality of working units arranged in an array.

[0067] In some embodiments, the working unit includes a shell, which defines a working chamber, the shell has an evaporation end and a condensation end, the working chamber contains a thermal barrier layer and a heat transfer medium, and a heat transfer medium adsorption layer is provided on the evaporation end of the shell in the working chamber.

[0068] In some embodiments, the housing comprises a polymer material. In some embodiments, the housing comprises a transparent material. In some embodiments, the housing comprises a transparent polymer material. In some embodiments, the housing comprises at least one of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and polyvinyl chloride (PVC).

[0069] In a second aspect of the present application, a method for preparing the aforementioned thermal diode is provided, the method comprising synthesizing a polymer ethanol gel, the steps of synthesizing the polymer ethanol gel comprising:

[0070] Mixing a polymerizable monomer, a cross-linking agent, an initiator and water to form a polymer hydrogel through a cross-linking reaction;

[0071] The polymer hydrogel is mixed with ethanol and replaced to generate a polymer ethanol gel.

[0072] In some embodiments, the step of synthesizing the polymer ethanol gel comprises:

[0073] The polymer monomer and the cross-linking agent are completely dissolved in water, the initiator is added and mixed, and the cross-linking reaction is carried out at 50 to 100° C. for 1 to 10 hours to prepare a polymer hydrogel;

[0074] The polymer hydrogel is soaked in ethanol for 4 to 6 hours to allow the ethanol to replace the water in the polymer hydrogel to generate a polymer ethanol gel.

[0075] In some embodiments, the mass ratio of the polymerizable monomer to the cross-linking agent is 100:0.5-5, for example, it can be 100:0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5.

[0076] In some embodiments, the mass ratio of the polymerization monomer to the initiator is 100:0.5-5, for example, it can be 100:0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5.

[0077] In some embodiments, the mass ratio of the polymerization monomer to water is 1:30-100, for example, 1:30, 40, 50, 60, 70, 80, 90, 100.

[0078] In a third aspect of the present application, a glass curtain wall is provided, which includes any of the aforementioned thermal diodes. In some embodiments, the glass curtain wall includes glass and a thermal diode located on one side of the glass. In some embodiments, the glass curtain wall includes a first glass layer, a thermal diode, and a second glass layer arranged in sequence.

[0079] In some embodiments, the angle between the glass curtain wall and the horizontal plane when assembled is more than 30°, for example, it can be more than 30, 45, 60, 75, 80, 85, 86, 87, 88, 89, 89.5°. In some embodiments, the angle between the glass curtain wall and the horizontal plane when assembled is 90°.

[0080] The fourth aspect of the present application provides the aforementioned thermal diode, or the application of the aforementioned glass curtain wall in the field of thermal management. Thermal management is to adjust and control the temperature and temperature difference by heating or cooling means. The thermal diode or glass curtain wall provided in the embodiment of the present application can achieve efficient spontaneous heat transfer without energy consumption, and can therefore be applied to the field of thermal management, specifically including but not limited to smart homes, wearable devices, medical supplies, smart agriculture, various vehicles (such as new energy vehicles, trains, airplanes, etc.), various venues (such as shopping malls, museums, art galleries, stadiums, airports, railway stations, bus stations, subway stations, etc.) and other scenes of thermal management.

[0081] Example 1

[0082] This embodiment provides a polyacrylic acid ethanol gel, and the preparation steps are as follows:

[0083] (1) 0.05832 g of N,N′-methylenebisacrylamide and 1.944 g of acrylic acid were added to 28.8 mL of deionized water and stirred until completely dissolved to obtain Solution 1.

[0084] (2) 3.6 mL of an aqueous solution of 0.072 g of ammonium persulfate was added to Solution 1 and stirred to obtain Solution 2.

[0085] (3) Solution 2 was injected into a glass mold with a length of 200 mm, a width of 80 mm, and a thickness of 2 mm using a syringe.

[0086] (4) The mold was heated in a 75° C. water bath for 3 hours to complete cross-linking and obtain a molded polyacrylic acid hydrogel.

[0087] (5) The prepared polyacrylic acid hydrogel was immersed in ethanol for 4 hours to replace the water in the hydrogel with ethanol to obtain polyacrylic acid ethanol gel.

[0088] refer to Figure 4 The transmittance of polyacrylic acid ethanol gel in the visible light band (Visible in the figure) was measured using a UV-visible-near infrared spectrophotometer (LAMBDA 1050+), which was over 76%, while the absorbance in the infrared band could reach 40%.

[0089] Example 2

[0090] This embodiment provides a thermal diode, referring to Figure 3, ethanol is used as the heat transfer medium 200, the polyacrylic acid ethanol gel prepared in Example 1 is used as the heat transfer medium adsorption layer 111, and the PVC board is used as a transparent outer frame to encapsulate ethanol and polyacrylic acid ethanol gel into it to form an independent thermal diode working unit. Among them, the thickness w of the polyacrylic acid ethanol gel is about 3mm due to swelling. It is placed on one side of the working unit and fits with the PVC board as the evaporation end 110. The PVC board on the side opposite to the evaporation end is used as the condensation end 120, and the air filled therein constitutes a thermal barrier layer 130. The lowest position of the PVC board at the condensation end 120 is higher than the lowest position of the PVC board at the evaporation end 110, so that the condensed ethanol will flow back from the condensation end 120 to the evaporation end 110 under the action of gravity and be adsorbed by the heat transfer medium adsorption layer 111. The distance l between the polyacrylic acid ethanol gel and the PVC board at the condensation end is 7mm, the thickness of the PVC boards at both ends is 3mm, and the thickness of the entire working unit is about 16mm.

[0091] In this thermal diode, when the temperature of the evaporation end is higher than that of the condensation end, the polyacrylic acid ethanol gel will evaporate the adsorbed ethanol therein, release heat and condense at the condensation end, and then slide to the bottom to be adsorbed by the polyacrylic acid ethanol gel again, forming a cycle. As a result, the heat transfer from the evaporation end to the condensation end can be continuously carried out by the evaporation-condensation process of ethanol. When the temperature of the condensation end is higher than that of the evaporation end, since there is no heat transfer medium ethanol on the condensation end, and there is air between the condensation end and the evaporation end to block the heat, its heat transfer coefficient is greatly reduced, thereby achieving the effect of heat preservation and heat insulation. Moreover, due to the strong volatility of ethanol at room temperature, even if there is no obvious temperature difference between the evaporation end and the condensation end, ethanol will spontaneously evaporate from the evaporation end to absorb heat and condense at the condensation end to release heat, achieving spontaneous heat transfer without energy consumption.

[0092] Example 3

[0093] This embodiment provides a glass curtain wall, which includes a supporting structure and glass installed on the supporting structure. The glass includes a glass body and a thermal diode on one side of the glass body. Figure 5 The working units of the thermal diode of Example 2 are sequentially assembled and arranged to form a 2×3 matrix thermal diode. The matrix thermal diode has a length of 288 mm, a width of 172 mm, and a thickness of 16 mm.

[0094] In winter, the evaporation end of the thermal diode in the transparent outer frame of the glass curtain wall faces the outside and the condensation end faces the inside. In the day, the thermal diode uses the heat of the sun and the heat of the outside environment to provide passive heating for the room and keep the room warm at night. In the summer, the evaporation end of the thermal diode in the transparent outer frame of the glass curtain wall faces the inside and the condensation end faces the outside. In the day, the thermal diode can insulate the high temperature outside and dissipate the indoor heat through evaporation-condensation at night to achieve passive cooling. In addition, the high volatility of ethanol at room temperature can achieve continuous heat transfer.

[0095] Example 4: Heat transfer experiment without temperature difference

[0096] refer to Figure 6 A thermal diode working unit for testing is constructed, including an evaporation end 110 and a condensation end 120. The evaporation end 110 is provided with the polyacrylic acid ethanol gel of Example 1 as a heat transfer medium adsorption layer 111. There is a heat barrier layer composed of air between the heat transfer medium adsorption layer 111 and the condensation end 120. A partition 300 is provided at the bottom of the working unit to separate it into an evaporation chamber 310 and a condensation chamber 320. A certain amount of ethanol is preset in the evaporation chamber 310 as a heat transfer medium 200. The working unit is sealed with a PVC board and placed in a constant temperature and humidity chamber at a specific temperature. After a period of time, the amount of ethanol condensed in the condensation chamber is measured, and the heat transfer rate Φ is calculated according to the following formula:

[0097]

[0098] Where m is the mass of condensed ethanol,

[0099] T is the condensation time,

[0100] A is the mass transfer (evaporation) area,

[0101] ΔH_vap is the enthalpy of vaporization of ethanol.

[0102] The calculation results show that at 15, 20, 25, and 30°C, 4.07, 4.35, 4.81, and 5.07 W / m can be achieved respectively. 2 Heat transfer without temperature difference.

[0103] It can be seen that the thermal diode can utilize the high volatility of ethanol at room temperature, spontaneously evaporate at the evaporation end to absorb heat and condense at the condensation end to release heat, without the need for additional energy input, thus achieving spontaneous and efficient heat transfer.

[0104] Example 5: Heat transfer coefficient test

[0105] For the thermal diode provided in Example 2, the heat transfer coefficients from the evaporation end to the condensation end and from the condensation end to the evaporation end are calculated respectively, and the method is as follows:

[0106] For the heat transfer coefficient from the evaporation end to the condensation end, at room temperature (25°C), a 20°C airflow is applied to the condensation end, and the wind speed is about 1m / s. After a period of time, the condensation amount of ethanol is obtained. The heat transfer rate is calculated according to the method of Example 4, and then the temperature difference between the two ends is obtained according to the temperature of the evaporation end and the condensation end. The heat transfer coefficient is calculated as heat transfer rate / temperature difference;

[0107] For the heat transfer coefficient from the condensation end to the evaporation side, the thermal conductivity of each component between the condensation end and the evaporation end is measured by a thermal conductivity meter, and then combined with the thickness to calculate The specific parameters are shown in the following table:

[0108] Table 1. Thermal conductivity of each component of the interface evaporation thermal diode glass curtain wall

[0109] Components Thermal conductivity λ(W / m·K) Thickness w(m) Air 0.025 0.007 Polyacrylic acid ethanol gel 0.3329 0.003 PVC 0.1770 0.003*2

[0110] The results show that at room temperature, the heat transfer coefficient from the evaporation end to the condensation end can reach 30.87W / (m 2 ·K), while the heat transfer coefficient from the condensation end to the evaporation end is only 3.10W / (m 2 ·K).

[0111] Example 6: Evaporation Type Comparison

[0112] A certain amount of ethanol is added into a container, and the polyacrylic acid ethanol gel prepared in Example 1 is vertically immersed therein for interfacial evaporation as the experimental group, and the same amount of ethanol is taken as the control group for bulk evaporation. The evaporation areas of the experimental group and the control group are controlled to be 5cm×5cm. The containers of the experimental group and the control group are placed on a balance and placed in a constant temperature box at 25°C. The balance outputs real-time data of the container mass, and a dot-line graph of mass versus time can be made based on the data. The slopes of the dot-line graphs are calculated respectively, and then the evaporation rate is calculated based on the slopes. The results are as follows: Figure 7 As shown in the figure, it can be seen that the evaporation rate of polyacrylic acid ethanol gel for interfacial evaporation is 1.71 kg / (m 2 ·h)) is significantly faster than the evaporation rate of bulk evaporation (0.71kg / (m 2 h)).

[0113] From the above examples, it can be seen that:

[0114] 1. The thermal diode provided in the embodiment of the present application uses ethanol instead of water as the heat transfer medium, which eliminates the need for equipment vacuuming caused by using water as the heat transfer medium, solves the problem of the high freezing point of water, and expands the operating temperature range.

[0115] 2. In the embodiment of the present application, the polymer ethanol gel (such as polyacrylic acid ethanol gel) is set as the interface evaporation material for evaporating ethanol. The polymer ethanol gel has a high affinity for ethanol and can provide material supplement for the evaporation of ethanol by rapidly absorbing and transmitting ethanol. The polymer ethanol gel also has a loose porous structure, which increases the evaporation area and achieves excellent ethanol interface evaporation performance.

[0116] 3. The thermal diode of the embodiment of the present application combines ethanol interface evaporation, and for the first time, the phase-change thermal diode structure is applied to the vertical building glass curtain wall. On the one hand, the heat transfer medium adsorption layer absorbs ethanol through capillary action and maintains it at a certain height, which removes the limitation of the horizontal placement of the traditional phase-change thermal diode, so that the thermal diode can be used in the glass curtain wall of the building envelope structure; on the other hand, the combination of the heat transfer medium adsorption layer and ethanol replaces the bulk evaporation in the thermal diode with the interface evaporation, which also brings about the improvement of heat transfer performance.

[0117] 4. The unique interfacial evaporation thermal diode provided in the embodiment of the present application allows the condensed ethanol droplets to flow back from the condensation end to the original ethanol solution at the evaporation end.

[0118] 5. The thermal diode provided in the embodiment of the present application innovatively proposes to perform energy-free spontaneous heat transfer by means of evaporation-condensation.

[0119] The present application is described in detail above in conjunction with the embodiments, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A thermal diode, characterized in that The method comprises at least one working unit, wherein the working unit comprises: An evaporation end, wherein the evaporation end is provided with a heat transfer medium adsorption layer, and the heat transfer medium adsorption layer comprises a polymer ethanol gel; A condensation end, the condensation end is located at a side of the working unit away from the evaporation end; A heat-blocking layer, wherein the heat-blocking layer is located between the evaporation end and the condensation end; A heat transfer medium is located at the evaporation end and is at least partially adsorbed in the heat transfer medium adsorption layer, and the heat transfer medium includes ethanol.

2. The thermal diode according to claim 1, characterized in that The polymer monomers forming the polymer ethanol gel include at least one of acrylic acid, acrylamide and vinyl pyrrolidone.

3. The thermal diode according to claim 2, characterized in that The raw materials for preparing the polymer ethanol gel include polymerization monomers, a cross-linking agent, an initiator and ethanol.

4. The thermal diode according to claim 3, characterized in that The initiator includes at least one of sodium persulfate, potassium persulfate, ammonium persulfate, 2,2'-azobisisopropylimidazoline hydrochloride, 2,2'-azo(2-methyl-N-(2-hydroxyethyl)propionamide) and 2,2-azabis(2-imidazoline) dihydrochloride; and / or, the cross-linking agent includes at least one of formaldehyde, glutaraldehyde, genipin, ethylene glycol diglycidyl ether, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate and pentaerythritol triallyl ether.

5. The thermal diode according to claim 1, characterized in that The bottom of the evaporation end is lower than the bottom of the condensation end.

6. The thermal diode according to claim 1, characterized in that The ratio of the thickness of the heat transfer medium adsorption layer to the distance between the heat transfer medium adsorption layer and the condensation end is 1:0.1-10.

7. The method for preparing a thermal diode according to any one of claims 1 to 6, characterized in that: The preparation method comprises synthesizing a polymer ethanol gel, and the steps of synthesizing the polymer ethanol gel include: Mixing a polymerizable monomer, a cross-linking agent, an initiator and water to form a polymer hydrogel through a cross-linking reaction; The polymer hydrogel is mixed with ethanol and replaced to generate a polymer ethanol gel.

8. Glass curtain wall, characterized in that: The glass curtain wall comprises the thermal diode according to any one of claims 1 to 6.

9. The glass curtain wall according to claim 8, characterized in that: The angle between the glass curtain wall and the horizontal plane during assembly is greater than 30°.

10. Use of the thermal diode according to any one of claims 1 to 6, or the glass curtain wall according to any one of claims 8 to 9 in the field of thermal management.

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