Bag body and radiation cooling device

Abstract

To suppress deterioration in radiation performance of radiating heat of a substance stored inside even under sunshine on a bag body that has heat radiation property.SOLUTION: A bag body with a multilayer structure includes: a radiation cooling layer constituting an outermost layer and having heat radiation property and light permeability through which sunlight is permeable; and a reflective layer constituting an inner layer relative to the radiation cooling layer and having light reflection property of reflecting sunlight.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a bag body and a radiative cooling device.

Background Art

[0002] Patent Document 1 discloses a radiative cooling device including a bag body and a working fluid. This bag body has a heat receiving part connected to a heating element and a radiative cooling part having heat radiation properties. Further, the working fluid is enclosed inside the bag body and transports heat from the heat receiving part to the radiative cooling part with a phase change. And the bag body of the radiative cooling device has softness, flexibility or stretchability and expands and contracts due to the phase change of the working fluid.

[0003] Patent Document 2 discloses a radiative cooling device including a bag body housed in a roll shape around a core body rotatable around an axis. The bag body of this radiative cooling device is provided with a heat receiving part that receives heat from a core body connected to a heating element and a radiative cooling part that radiates heat. Further, a working fluid that transports heat from the heat receiving part to the radiative cooling part with a phase change is enclosed inside the bag body. Inside the bag body, when the working fluid changes to a gas phase, the bag body expands due to an increase in internal pressure.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the technique disclosed in Patent Document 1, the working fluid radiates the heat received from the heating element from the radiative cooling part of the bag body. However, in the case of sunlight, since sunlight passes through the bag body, even if heat is radiated from the radiative cooling part, the liquefied working fluid is warmed by the sunlight, so the cooling efficiency of the heating element tends to decrease.

[0006] In addition, in the technology disclosed in Patent Document 2, similar to the technology disclosed in Patent Document 1, the working fluid dissipates the heat received from the heating element from the radiation cooling portion of the bag body. However, in the case of sunlight, since the sunlight passes through the bag body, even if heat is dissipated from the radiation cooling portion, the liquefied working fluid is warmed by the sunlight, so the cooling efficiency of the heating element tends to decrease.

[0007] An object of the present disclosure is to suppress a decrease in heat dissipation performance of dissipating heat of a substance accommodated inside a bag body having heat radiation even under sunlight.

Means for Solving the Problems

[0008] The bag body according to the first aspect of the present disclosure is a bag body having a multilayer structure, including a radiation cooling layer that forms the outermost layer and has heat radiation and light transmissibility that transmits sunlight, and a layer inside the radiation cooling layer that forms a reflective layer having light reflectivity that reflects sunlight.

[0009] In the bag body according to the first aspect, when a substance is accommodated inside, the radiation cooling layer that forms the outermost layer and has heat radiation dissipates heat by radiating the heat transmitted from the substance to the outside as infrared light. Since this radiation cooling layer has light transmissibility, sunlight passes through it, but the transmitted sunlight is reflected by the reflective layer. Therefore, the sunlight is suppressed from reaching the inside of the bag body by the reflective layer. As a result, an increase in the temperature of the substance inside the bag body due to sunlight is suppressed. That is, the above bag body suppresses a decrease in heat dissipation performance of dissipating heat of a substance accommodated inside even under sunlight. Therefore, the above bag body can dissipate and cool the heat of a substance accommodated inside even under sunlight.

[0010] The bag body according to the second aspect of the present disclosure is the bag body according to the first aspect, in which the innermost layer is constituted by a protective layer that protects the reflective layer.

[0011] In the bag body according to the second aspect, by using the protective layer that protects the reflective layer as the innermost layer, it becomes possible to protect the reflective layer from the substance accommodated inside. Thereby, the durability of the above bag body is improved.

[0012] In the bag body according to the third aspect of the present disclosure, in the bag body according to the second aspect, the protective layer is made of a material having corrosion resistance and abrasion resistance equal to or higher than those of the reflective layer.

[0013] In the bag body according to the third aspect, by configuring the protective layer with a material having corrosion resistance and abrasion resistance equal to or higher than those of the reflective layer, even when the substance stored inside has high reactivity with the reflective layer, the reflective layer can be protected by the protective layer, thereby suppressing discoloration of the reflective layer and the like. Further, since the reflective layer is protected by the protective layer from, for example, the substance stored inside, abrasion of the reflective layer is less likely to occur. Therefore, since the reflective layer of the above bag body is protected by the protective layer made of the above material, the durability is improved.

[0014] In the bag body according to the fourth aspect of the present disclosure, in the bag body according to the third aspect, the material constituting the protective layer includes Inconel.

[0015] In the bag body according to the fourth aspect, by including Inconel, which is excellent in corrosion resistance and heat resistance, in the material constituting the protective layer, it is possible to obtain the effect of protecting for a long period of time.

[0016] In the bag body according to the fifth aspect of the present disclosure, in the bag body according to the first aspect, the radiative cooling layer is made of a material having a solar transmittance of 80% or more and an infrared emissivity of 50% or more.

[0017] In the bag body according to the fifth aspect, when the solar transmittance of the material constituting the radiative cooling layer is less than 80%, the effect of reflecting sunlight by the reflective layer through the radiative cooling layer cannot be sufficiently ensured. Further, when the infrared emissivity of the material constituting the radiative cooling layer is less than 50%, the heat dissipation performance of dissipating the heat of the substance stored inside cannot be sufficiently ensured. Therefore, it is preferable that the radiative cooling layer is made of a material having a solar transmittance of 80% or more and an infrared emissivity of 50% or more.

[0018] In the bag body according to the sixth aspect of the present disclosure, in the bag body according to the first aspect, the material constituting the radiative cooling layer includes a transparent fluororesin.

[0019] In the bag body of the sixth aspect, the material constituting the radiative cooling layer includes a transparent fluororesin excellent in heat resistance, abrasion resistance, weather resistance, etc. Therefore, the durability of the outermost layer of the bag body is improved. As a result, it becomes possible to use the bag body over a long period of time.

[0020] The bag body of the seventh aspect of the present disclosure is the bag body of the first aspect, wherein the reflective layer is made of a material having a solar reflectance of 80% or more.

[0021] In the bag body of the seventh aspect, when the solar reflectance of the material constituting the reflective layer is less than 80%, the solar reflectance performance is not sufficient, and when a substance is contained inside, the heat dissipation performance for dissipating the heat of the substance deteriorates. Therefore, the reflective layer is preferably made of a material having a solar reflectance of 80% or more.

[0022] The bag body of the eighth aspect of the present disclosure is the bag body of the first aspect, wherein the reflective layer is made of a metal material.

[0023] In the bag body of the eighth aspect, by forming the reflective layer of a metal material, when a substance is contained inside, the heat of the substance easily transfers to the radiative cooling layer through the reflective layer. Also, by forming the reflective layer of a metal material, it is easy to improve the solar reflectance.

[0024] The bag body of the ninth aspect of the present disclosure is the bag body of the first aspect, and has a joint portion where the outer surface and the inner surface of the film constituting the radiative cooling layer are joined by welding.

[0025] In the bag body of the ninth aspect, since the outer surface and the inner surface of the film constituting the radiative cooling layer are joined by welding to form a joint portion, for example, compared with a configuration in which the inner surface and the inner surface of the film or the outer surface and the outer surface of the film are joined by welding to form a joint portion, flexibility at the joint portion can be ensured. As a result, for example, when the bag body is inflated, stress concentration at the joint portion can be suppressed. Therefore, the durability of the above bag body is improved.

[0026] The radiative cooling device according to the tenth aspect of the present disclosure includes a heat generating body, a container that houses the heat generating body and a refrigerant that vaporizes with the heat of the heat generating body, and a bag body of any one of the first to ninth aspects that is attached to the container and has an interior communicating with the interior of the container and bulges upward in the gravitational direction from the container as the refrigerant vaporizes.

[0027] In the radiative cooling device according to the tenth aspect, when the refrigerant in the container vaporizes due to the heat of the heat generating body as a substance housed inside the bag body, the vaporized refrigerant (vapor) moves into the bag body attached to the container. Due to the movement of the vapor, the bag body bulges upward in the gravitational direction from the container. Then, when the heat of the vapor is transmitted to the bag body, the thermal energy of the transmitted heat is radiated from the bag body as electromagnetic waves. Also, when the heat of the vapor is taken away from the bag body, the vapor liquefies. That is, the refrigerant condenses from the vapor into droplets. These droplets fall along the inner surface of the bag body that has bulged upward in the gravitational direction due to their own weight and return to the container. In this way, in the above radiative cooling device, the heat generating body is cooled by the heat of the heat generating body being radiated through the bag body.

[0028] Further, in the bag body of the radiative cooling device according to the tenth aspect, a radiative cooling layer that forms the outermost layer and has heat radiation properties radiates the heat transmitted from the heat generating body to the outside as infrared light to dissipate heat. Since this radiative cooling layer has light transmissivity, sunlight passes through, but the transmitted sunlight is reflected by the reflective layer. Therefore, the sunlight is suppressed by the reflective layer from reaching the inside of the bag body. As a result, the temperature rise of the substance inside the bag body due to sunlight is suppressed. That is, the above bag body suppresses a decrease in the heat dissipation performance of dissipating the heat of the substance housed inside even under sunlight. Therefore, the above bag body can dissipate and cool the heat of the substance housed inside even under sunlight.

Advantages of the Invention

[0029] According to the present disclosure, in a bag body having heat radiation properties, it is possible to suppress a decrease in the heat dissipation performance of dissipating the heat of the substance housed inside even under sunlight.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0031] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. Components denoted by the same reference numerals in each drawing are meant to be the same or similar components. In the embodiments described below, redundant explanations and reference numerals may be omitted. Also, the drawings used in the following explanations are all schematic, and the dimensional relationships of the respective elements shown in the drawings, the ratios of the respective elements, etc. do not necessarily match the actual ones. Also, the dimensional relationships of the respective elements, the ratios of the respective elements, etc. do not necessarily match even between multiple drawings.

[0032] As shown in FIG. 1, a radiative cooling device 20 according to an embodiment of the present disclosure includes a container 30 and a bag body 40.

[0033] (Container 30) As shown in FIG. 1, the container 30 houses a heating element HE and a refrigerant F that is vaporized by the heat of the heating element HE. This container 30 has a ceiling portion 30A, a bottom portion 30B, and side wall portions 30C. In the present embodiment, as an example, the container 30 is shaped like a rectangular box.

[0034] Further, the upper part of one of the four side wall portions 30C is inclined obliquely. This inclined portion will be hereinafter referred to as the inclined portion 32 as appropriate. Also, the side wall portion 30C having the inclined portion 32 will be hereinafter referred to as the side wall portion 30C1 as appropriate. This inclined portion 32 is inclined toward the inside of the container 30.

[0035] A through hole 32A is formed in the inclined portion 32. A cylindrical attachment port 34 is fixed to the outer surface of the inclined portion 32 so as to communicate with the through hole 32A. Further, the attachment port 34 is fixed to the inclined portion 32 on the upper side in the direction of gravity (the side indicated by the arrow UP), specifically, so as to face obliquely upward in the direction of gravity. As shown in FIGS. 4 and 5, this attachment port 34 has a cylindrical portion 34A, a flange portion 34B, and a tapered portion 34C.

[0036] As shown in FIG. 4, the flange portion 34B is an overhanging portion that projects radially outward from one end side in the axial direction of the cylindrical portion 34A. This flange portion 34B is fixed to the peripheral portion of the through hole 32A in the inclined portion 32 (see FIG. 1). The fixing method of the flange portion 34B and the inclined portion 32 is not particularly limited. For example, fastening using a fastening component such as a screw may be used, fixing using an adhesive may be used, or welding may be used. Further, as long as the attachment port 34 can be fixed to the inclined portion 32, it is not limited to the above fixing method.

[0037] As shown in FIG. 4, the tapered portion 34C is formed at the other end in the axial direction of the cylindrical portion 34A. Specifically, the tapered portion 34C is a portion of the cylindrical portion 34A that tapers toward the other end in the axial direction of the cylindrical portion 34A. In FIG. 5, the minimum diameter of the tapered portion 34C is D min , the maximum diameter is D maxIt is shown by []. Also, in FIG. 5, the inner diameter of the entrance / exit portion 40A of the bag body 40 is indicated by 40D. As shown in FIGS. 1 and 6, the entrance / exit portion 40A of the bag body 40 is in contact with this tapered portion 34C. Specifically, the inner surface constituting the entrance / exit portion 40A of the bag body 40 is in contact with the surface of the mounting port 34 constituting the tapered portion 34C.

[0038] Also, the container 30 of the present embodiment is a rigid body. Specifically, the container 30 is formed of a metal material. As the metal material, for example, iron, copper, or an aluminum alloy may be used. Note that the metal material constituting the container 30 is preferably a metal material having a Young's modulus of 70 Mpa or more.

[0039] As shown in FIG. 1, a refrigerant F is accommodated inside the container 30, in other words, the refrigerant F is stored. The heating element HE is immersed in the stored refrigerant F. The heating element HE of the present embodiment is, as an example, a metal pipe that penetrates the container 30. The pipe penetrates the side wall portions 30C adjacent to both sides of the side wall portion 30C1. Refrigerant flows inside the pipe. This refrigerant exchanges heat with the refrigerant F through the pipe.

[0040] As the refrigerant F accommodated in the container 30, for example, water or alternative freon etc. may be used. Note that the type of the refrigerant F is not limited to these.

[0041] (Bag body 40) As shown in Fig. 1, the bag body 40 has heat radiation, is attached to the container 30, and its interior communicates with the interior of the container 30. It is configured to expand upward in the gravitational direction from the container 30 as the refrigerant F vaporizes. Specifically, the bag body 40 has a cylindrical shape with a closed tip. The base end of this bag body 40 constitutes the entrance / exit portion 40A. The entrance / exit portion 40A of the bag body 40 is attached to the attachment port 34 as shown in Fig. 6. Specifically, the attachment port 34 is inserted into the entrance / exit portion 40A of the bag body 40. Therefore, the interior of the bag body 40 communicates with the interior of the container 30 via the attachment port 34. Also, in a state where the attachment port 34 is inserted into the entrance / exit portion 40A of the bag body 40, the attachment port 34 is held in a state of being inserted into the entrance / exit portion 40A of the bag body 40 by sandwiching the entrance / exit portion 40A of the bag body 40 between the tapered portion 34C of the attachment port 34 and the inclined inner peripheral surface 70A of the annular holding member 70. For example, grease or the like may be applied to the tapered portion 34C before attaching the bag body 40. By doing so, the tapered portion 34C and the bag body 40 are likely to be in close contact, improving the sealing performance. In this embodiment, the holding member 70 is fixed to the flange portion 34B of the attachment port 34 using a fastening component such as a screw (not shown).

[0042] As described above, since the base end (entrance / exit portion 40A) of the bag body 40 is attached to the attachment port 34, the tip is a free end. Therefore, when the vaporized refrigerant (hereinafter, the vaporized refrigerant is referred to as "vapor V") moves from the container 30 to the bag body 40 in a deflated state, the bag body 40 expands. Here, since the attachment port 34 faces upward in the gravitational direction, specifically, obliquely upward in the gravitational direction, the cylindrical bag body 40 also expands upward in the gravitational direction from the container 30, specifically, obliquely upward in the gravitational direction.

[0043] Note that Fig. 1 shows a state where the bag body 40 is expanded and deployed. When the refrigerant F is in a liquid phase state (liquefied state), the bag body 40 deflates and enters a storage state. The storage state of the bag body 40 may be, for example, a state of being wound up in a roll shape, a folded state, or is not particularly limited.

[0044] In addition, in this embodiment, one bag body 40 is attached to one container 30, but the present disclosure is not limited to this configuration. A plurality of bag bodies 40 may be attached to one container 30. In this case, the swelling directions of the respective bag bodies 40 may be different from each other or the same. Further, for example, the bag body 40 may be attached to the ceiling portion 30A of the container 30. However, when the swelling directions of the respective bag bodies 40 are the same, an effect of effectively utilizing the space around the container 30 can be obtained.

[0045] Also, the bag body 40 preferably has such softness that it can be deployed and stored.

[0046] As shown in FIG. 2, the bag body 40 is a bag body having a multilayer structure. The bag body 40 includes a radiative cooling layer 42 and a reflective layer 44. Further, the bag body 40 may include a protective layer 46.

[0047] <Radiative cooling layer 42> The radiative cooling layer 42 forms the outermost layer of the bag body 40. This radiative cooling layer 42 has heat radiation properties and light transmissibility that transmits sunlight (including visible light). The radiative cooling layer 42 is preferably composed of a material having a sunlight transmittance of 80% or more and an infrared light emissivity of 50% or more. The material constituting such a radiative cooling layer 42 preferably includes a transparent fluororesin. As the transparent fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), perfluoroalkoxyethyl ether copolymer (PFA), or ethylene tetrafluoroethylene copolymer (ETFE) may be used.

[0048] <Reflective layer 44> The reflective layer 44 constitutes a layer inside the radiative cooling layer 42 of the bag body 40. This reflective layer 44 has light reflectivity for reflecting sunlight. Preferably, this reflective layer 44 is composed of a material with a sunlight reflectivity of 80% or more. Also, preferably, the reflective layer 44 is composed of a metallic material. Examples of the metallic material constituting the reflective layer 44 include silver and aluminum. Further, for improving the reflectivity, it is preferable to form an electrolytically polished surface on the aluminum. Note that the material of the reflective layer 44 is not limited as long as it can reflect sunlight VL.

[0049] <The protective layer 46> The protective layer 46 constitutes the innermost layer of the bag body 40. This protective layer 46 is a layer for protecting the reflective layer 44. This protective layer 46 is composed of a material having corrosion resistance and abrasion resistance equal to or higher than those of the reflective layer 44. Preferably, the material constituting the protective layer 46 includes Inconel. Also, the material constituting the protective layer 46 may include stainless steel.

[0050] Also, the bag body 40 of the present embodiment has a joint portion 40B formed by welding the outer surface 41O and the inner surface 41I of the film 41 constituting the radiative cooling layer 42 (see FIG. 3A). As shown in FIG. 3B, this joint portion 40B is formed by welding the ends of the radiative cooling layers 42 on both sides of the film 41 after removing the reflective layer 44 and the protective layer 46 in such a manner that the ends of the radiative cooling layers 42 overlap each other. This joint portion 40B is formed along the longitudinal direction of the bag body 40 (in the direction of the central axis CL in the inflated state).

[0051] Also, for the bag body 40 of the present embodiment, it is preferable to set the combined thickness of the reflective layer 44 and the protective layer 46 to 10 μm or less and the thickness of the radiative cooling layer 42 to 50 μm or more and 50 μm or less. By setting the thicknesses of the respective layers constituting the bag body 40 to the above values, the flexibility of the bag body 40 can be ensured.

[0052] Here, as shown in FIG. 1, when the refrigerant F is heated by the heat of the heating element HE and undergoes a phase change from the liquid phase to the gas phase (vaporization), vapor V is generated. Then, as the refrigerant F vaporizes, the internal pressure of the bag body 40 increases, and the bag body 40 expands and unfolds upward in the direction of gravity.

[0053] The heat of the vapor V generated inside the bag body 40 is transmitted from the inner surface of the bag body 40 to the radiation cooling layer 42, and the thermal energy of the transmitted heat is released as electromagnetic waves EW (including infrared light). Also, when the heat of the vapor V is thus taken away by the radiation cooling layer 42, the vapor V changes from the gas phase to the liquid phase, and the vapor V condenses into droplets D. These droplets D fall due to their own weight.

[0054] By repeating the above operations, by means of the so-called thermosiphon method, with the phase change of the refrigerant F, the heat of the heating element HE is transferred to the radiation cooling layer 42 of the bag body 40, and the thermal energy is released from the radiation cooling layer 42 as electromagnetic waves EW, thereby cooling the heating element HE.

[0055] When the heating element HE is cooled and the temperature inside the container 30 decreases, the internal pressure of the bag body 40 decreases, and the bag body 40 begins to shrink from the inflated state. At this time, the bag body 40 is, for example, wound up in a roll shape or folded to be in a stored state.

[0056] As described above, the container 30 and the bag body 40 of the present embodiment constitute a radiation cooling device 20 having a function as a radiator that releases the thermal energy of the heating element HE that generates heat as electromagnetic waves EW to cool the heating element HE.

[0057] Next, the operation of the present embodiment will be described. In the radiative cooling device 20 of the present embodiment, as described above, when the refrigerant F in the container 30 vaporizes due to the heat of the heating element HE, the vaporized refrigerant (vapor V) moves into the bag 40 attached to the container 30. The movement of the vapor V causes the bag 40 to expand upward in the gravitational direction from the container 30. When the heat of the vapor is transmitted to the bag 40, the thermal energy of the transmitted heat is radiated from the bag 40 as electromagnetic waves EW. Also, when the heat of the vapor V is taken away from the bag 40, the vapor V liquefies. That is, the refrigerant F condenses from the vapor V into droplets D. These droplets D fall along the inner surface of the bag 40 that has expanded upward in the gravitational direction due to their own weight and return to the inside of the container 30. Thus, in the radiative cooling device 20, the heating element HE is cooled by the heat of the heating element HE being radiated through the bag 40.

[0058] In the bag 40 of the present embodiment, the radiative cooling layer 42 that forms the outermost layer and has heat radiation properties radiates heat to the outside as electromagnetic waves EW (including infrared light) the heat transmitted from the vaporized refrigerant F. As shown in FIG. 2, since this radiative cooling layer 42 has light transmissibility, sunlight VL passes through it, but the transmitted sunlight VL is reflected by the reflective layer 44. Therefore, the sunlight VL is suppressed from reaching the inside of the bag 40 by the reflective layer 44. As a result, an increase in the temperature of the refrigerant F inside the bag 40 due to the sunlight VL is suppressed. That is, the bag 40 suppresses a decrease in the heat dissipation performance of dissipating the heat of the vaporized refrigerant F inside even under sunlight. Therefore, the bag 40 can dissipate and cool the heat of the vaporized refrigerant F inside even under sunlight. Thereby, the heat dissipation performance is improved by the above-described radiative cooling device 20.

[0059] In the bag 40 of the present embodiment, by making the protective layer 46 that protects the reflective layer 44 the innermost layer, it becomes possible to protect the reflective layer 44 from the substances contained inside. Thereby, the durability of the bag 40 is improved.

[0060] In the bag body 40 of the present embodiment, by forming the protective layer 46 with a material having corrosion resistance and abrasion resistance equal to or greater than those of the reflective layer 44, even when the substance contained inside has high reactivity with the reflective layer 44, the reflective layer 44 can be protected by the protective layer 46, so that discoloration or the like of the reflective layer 44 can be suppressed. Further, since the reflective layer 44 is protected by the protective layer 46, for example, abrasion caused by contact between the reflective layers 44 due to bending or the like is suppressed. Thus, since the reflective layer 44 is protected by the protective layer 46 in the bag body 40, the durability is improved.

[0061] In the bag body 40 of the present embodiment, by including Inconel, which is excellent in corrosion resistance and heat resistance, in the material constituting the protective layer 46, it becomes possible to obtain the effect of protecting for a long period of time.

[0062] In the bag body 40 of the present embodiment, when the solar transmittance of the material constituting the radiative cooling layer 42 is less than 80%, the effect of reflecting the sunlight VL by the reflective layer 44 through the radiative cooling layer 42 cannot be sufficiently ensured. Further, when the infrared emissivity of the material constituting the radiative cooling layer 42 is less than 50%, the heat dissipation performance of dissipating the heat transmitted from the vaporized refrigerant F cannot be sufficiently ensured. Therefore, the radiative cooling layer 42 is preferably made of a material having a solar transmittance of 80% or more and an infrared emissivity of 50% or more.

[0063] In the bag body 40 of the present embodiment, the material constituting the radiative cooling layer 42 contains a transparent fluororesin that is excellent in heat resistance, abrasion resistance, weather resistance, and the like. Thereby, the durability of the outermost layer of the bag body 40 is improved. Thereby, it becomes possible to use the bag body 40 for a long period of time.

[0064] In the bag body 40 of the present embodiment, when the solar reflectance of the material constituting the reflective layer 44 is less than 80%, the sunlight reflection performance is not sufficient, and when a substance is contained inside, the heat dissipation performance of dissipating the heat of the substance decreases. Therefore, the reflective layer 44 is preferably made of a material having a solar reflectance of 80% or more.

[0065] In the bag body 40 of the present embodiment, by forming the reflective layer 44 with a metallic material, the heat of the vaporized refrigerant F is easily transmitted to the radiative cooling layer 42 through the reflective layer 44. Further, by forming the reflective layer 44 with a metallic material, it is easy to improve the solar light reflectance.

[0066] In the bag body 40 of the present embodiment, since the outer surface 41O and the inner surface 41I of the film 41 constituting the radiative cooling layer 42 are joined by welding to form the joint portion 40B, for example, compared with a configuration in which the inner surfaces 41I of the films 41 or the outer surfaces 41O of the films 41 are joined by welding to form the joint portion 40B, flexibility at the joint portion 40B can be ensured. Thereby, for example, when the bag body 40 is inflated, it is possible to suppress the occurrence of stress concentration at the joint portion 40B. Therefore, the durability of the bag body 40 is improved.

[0067] [Application Example] Next, an example to which the technology of the present disclosure is applicable will be described.

[0068] As shown in FIG. 7, the radiative cooling device 20 in the above-described embodiment may be used, for example, as a radiator of an outdoor unit 82 installed on the rooftop of a building 80. That is, the radiative cooling device 20 functions as a radiator of the outdoor unit when a pipe as a heating element HE is connected to the outdoor unit. Thereby, the heat of the outdoor unit can be emitted as electromagnetic waves EW from the radiative cooling layer 42. The building 80 is, for example, a building, a factory, or the like. According to this application example, it is possible to efficiently cool an outdoor unit that requires a large output. Further, since the performance of the outdoor unit improves as the ambient temperature becomes lower, further performance improvement of the outdoor unit can be expected by using the radiative cooling device 20. Note that the above application example of the present disclosure is merely an example.

[0069] As described above, one embodiment of the technology disclosed in the present application has been described. However, the technology disclosed in the present application is not limited to the above, and it goes without saying that various modifications can be made without departing from the gist thereof.

[0070] Regarding the above embodiments, the following is further disclosed.

[0071] (Appendix 1) A bag body with a multilayer structure, A radiation cooling layer that forms the outermost layer and has light transmissibility for transmitting thermal radiation and sunlight, A reflective layer that forms a layer inside the radiation cooling layer and has light reflectivity for reflecting sunlight, A bag body provided with the above.

[0072] (Appendix 2) The bag body according to Appendix 1, wherein the innermost layer is constituted by a protective layer that protects the reflective layer.

[0073] (Appendix 3) The bag body according to Appendix 2, wherein the protective layer is constituted by a material having corrosion resistance and wear resistance equal to or higher than that of the reflective layer.

[0074] (Appendix 4) The bag body according to Appendix 3, wherein the material constituting the protective layer includes Inconel.

[0075] (Appendix 5) The bag body according to any one of Appendices 1 to 4, wherein the radiation cooling layer is constituted by a material having a sunlight transmittance of 80% or more and an infrared light emissivity of 50% or more.

[0076] (Appendix 6) The bag body according to any one of Appendices 1 to 5, wherein the material constituting the radiation cooling layer includes a transparent fluororesin.

[0077] (Appendix 7) The bag body according to any one of Appendices 1 to 6, wherein the reflective layer is constituted by a material having a sunlight reflectivity of 80% or more.

[0078] (Appendix 8) The bag body according to any one of Appendices 1 to 7, wherein the reflective layer is constituted by a metal material.

[0079] (Appendix 9) The bag body according to any one of Appendices 1 to 8, having a joint portion where the outer surface and the inner surface of the film constituting the radiation cooling layer are joined by welding.

[0080] (Appendix 10) A heating element, a container that houses a refrigerant that vaporizes with the heat of the heating element, A bag body according to any one of Appendices 1 to 9, which is attached to the container and has an interior that communicates with the interior of the container and expands upward in the gravitational direction from the container as the refrigerant vaporizes, A radiation cooling device comprising the same.

Explanation of Signs

[0081] 20 Radiation cooling device 30 Container 40 Bag body 42 Radiation cooling layer 44 Reflective layer 46 Protective layer EW Electromagnetic wave F Refrigerant HE Heating element VL Sunlight

Claims

1. A bag body having a multi-layer structure, comprising a radiation cooling layer that forms the outermost layer and has light transmissibility for transmitting thermal radiation and sunlight, and a reflective layer that forms a layer inside the radiation cooling layer and has light reflectivity for reflecting sunlight. The bag body is provided with these layers.

2. The bag body according to Claim 1, wherein the innermost layer is constituted by a protective layer that protects the reflective layer.

3. The bag body according to Claim 2, wherein the protective layer is constituted by a material having corrosion resistance and abrasion resistance equal to or higher than that of the reflective layer.

4. The bag body according to Claim 3, wherein the material constituting the protective layer includes Inconel.

5. The bag body according to Claim 1, wherein the radiation cooling layer is constituted by a material having a sunlight transmittance of 80% or more and an infrared light emissivity of 50% or more.

6. The bag body according to Claim 1, wherein the material constituting the radiation cooling layer includes a transparent fluororesin.

7. The bag body according to Claim 1, wherein the reflective layer is constituted by a material having a sunlight reflectivity of 80% or more.

8. The bag body according to Claim 1, wherein the reflective layer is constituted by a metal material.

9. The bag body according to Claim 1, having a joint portion where the outer surface and the inner surface of the film constituting the radiation cooling layer are joined by welding.

10. A heating element, a container for containing a refrigerant that vaporizes with the heat of the heating element, and the bag body according to any one of Claims 1 to 9, which is attached to the container and has an interior communicating with the interior of the container and bulges upward in the gravitational direction from the container as the refrigerant vaporizes. A radiation cooling device provided with these components.

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