heat exchange device

Abstract

This invention provides a heat exchange device equipped with a novel heat exchange means that differs from conventional heat pump systems. [Solution] The heat exchange device comprises a heat exchange unit. The heat exchange unit includes a heat absorption and heat dissipation section containing a porous material whose pore size changes in response to light stimulation, and a medium that adsorbs and desorbs onto the porous material; a housing section that houses the heat absorption and heat dissipation section; a light stimulation input unit that applies the light stimulation to the porous material; and a heat exchange channel provided to penetrate the interior of the housing section, through which a heat transfer medium that is heated or cooled by heat exchange with the heat absorption and heat dissipation section flows.

Description

[Technical Field]

[0001] This invention relates to a heat exchange device. [Background technology]

[0002] Conventionally, heat exchange devices that heat or cool objects (spaces or objects) by transferring heat have been widely used. For example, according to Patent Document 1 below, a photoresponsive heat pump system has been proposed that uses a predetermined azobenzene compound that undergoes a cis-trans isomerization reaction upon light irradiation as a heat transfer medium, and utilizes the latent heat associated with the phase change of the azobenzene compound due to light irradiation. Such a heat pump system is said to be able to transfer heat from a low-temperature environment to a high-temperature environment with less energy because it does not require external energy input using equipment such as a compressor. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2015-143196 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention aims to provide a heat exchange device equipped with a novel heat exchange means that differs from conventional heat pump systems such as those proposed in Patent Document 1.

[0005] One embodiment of the present invention relates to a heat exchange apparatus comprising a heat exchange unit. The heat exchange unit is characterized in that it comprises a heat absorption and heat dissipation section containing a porous material whose pore size changes in response to light stimulation, and a medium that adsorbs and desorbs to the porous material, a housing section that houses the heat absorption and heat dissipation section, a light stimulation input unit that applies the light stimulation to the porous material, and a heat exchange channel provided to penetrate the interior of the housing section, through which a heat medium that is heated or cooled by heat exchange with the heat absorption and heat dissipation section flows. [Effects of the Invention]

[0006] According to the present invention, a heat exchange device is provided that is equipped with a novel heat exchange means different from conventional heat pump systems. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 shows a heat exchange device 10 according to the first embodiment. [Figure 2] Figure 2 is a cross-sectional view illustrating the configuration of the heat exchange unit 100 shown in Figure 1. [Figure 3] Figure 3 schematically illustrates how, in a heat exchanger according to one embodiment of the present invention, the pore size of a porous material changes due to light stimulation, and how a medium is adsorbed and desorbed from the porous material as a result. Figure 3(a) shows how, when the pore size of the porous material is relatively large due to irradiation with visible light (Vis), azobenzene, a photoisomerized compound, is adsorbed onto the surface of the inner wall of the pores, forming a meniscus. Figure 3(b) shows how, when the pore size of the porous material is relatively small due to irradiation with ultraviolet light (UV), the meniscus collapses and azobenzene, a photoisomerized compound, is desorbed from the surface of the inner wall of the pores. [Figure 4] This is an explanatory diagram illustrating one cycle in which the heat exchange unit 100 returns to its original state after going through an exothermic process (which can heat the heat transfer medium) and an absorbent process (which can cool the heat transfer medium). [Figure 5]Figure 5 is an explanatory diagram illustrating how control is implemented to switch between each flow path when continuously heating or cooling a heat transfer medium (water) using multiple heat exchange units U1, U2, and U3. [Figure 6] Figure 6 shows an example of a modified heat-absorbing section. Figure 6(a) is a schematic diagram showing the outline of the heat-absorbing section, and Figure 6(b) is a cross-sectional view of the hollow flow channel inside the carrier along a plane perpendicular to the flow direction of the heat transfer medium (air). [Figure 7] Figure 7 shows the nitrogen adsorption / desorption isotherms for the porous material prepared in the example, under three conditions: no UV irradiation (OFF-OFF), UV irradiation during both the adsorption and desorption processes (ON-ON), and UV irradiation only during the desorption process after saturated adsorption (OFF-ON). [Modes for carrying out the invention]

[0008] The embodiments of the present invention described above will be explained below with reference to the drawings, but the technical scope of the present invention should be determined based on the claims and is not limited to the following forms. Note that the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios.

[0009] 《First Embodiment》 Figure 1 shows a heat exchange device 10 according to the first embodiment. As shown in Figure 1, the heat exchange device 10 comprises a plurality of heat exchange units 100 and a medium pressure adjustment means 200. The heat exchange unit 100 includes an absorption / heating section 110, a housing 120 (an example of the "housing section" of the present invention), a visible light irradiation device 130A and an ultraviolet light irradiation device 130B (an example of the "photostimulation input unit" of the present invention), and a heating heat exchange channel 140A and a cooling heat exchange channel 140B (an example of the "heat exchange channel" of the present invention). The medium pressure adjustment means 200 consists of a medium tank 210 in which water, which is the medium, is stored, a medium channel 220 through which the water, which is the medium, flows, and a pressurizing pump 232 and a depressurizing pump 234 that control the supply of the medium (water) from the medium tank.

[0010] Figure 2 is a cross-sectional view illustrating the configuration of the heat exchange unit 100 shown in Figure 1. As shown in Figure 2, the heat absorption and heating section 110 includes a porous material 112 and a medium (water in this case; not shown) that adsorbs and desorbs to the porous material. In this embodiment, the pore size of the porous material 112 changes in response to an external stimulus, which is a light stimulus, and this light stimulus consists of two or more light stimuli with different wavelengths. Specifically, when visible light is irradiated onto the porous material 112, its pore size decreases, and the medium (water) is adsorbed into the pores of the porous material 112. During this adsorption, latent heat of condensation is released, causing the temperature of the heat absorption and heating section 110 to rise and generating heat. On the other hand, when ultraviolet light is irradiated onto the porous material 112, its pore size increases, and the medium (water) is desorbed from the pores of the porous material 112. During this desorption, latent heat of vaporization is absorbed, causing the temperature of the heat absorption and heating section 110 to decrease and generating cold. Therefore, the heat absorption and heating section 110 of the heat exchange unit 100 functions as a heat source or a cold source by switching between visible light irradiation and ultraviolet light irradiation.

[0011] The housing 120 houses the heat-absorbing and heating section 110 inside. A visible light irradiation device 130A is positioned on one side of the rectangular parallelepiped-shaped heat-absorbing and heating section 110 so as to be able to irradiate the section 110 with visible light (Vis). Furthermore, an ultraviolet light irradiation device 130B is positioned on the opposite side of the heat-absorbing and heating section 110 so as to be able to irradiate the section 110 with ultraviolet light (UV). In this embodiment, the visible light irradiation device 130A and the ultraviolet light irradiation device 130B are also housed inside the housing 120.

[0012] In the present embodiment, two heat exchange flow paths (i.e., a heating heat exchange flow path 140A and a cooling heat exchange flow path 140B) are provided so as to penetrate the inside of the housing 120. These heat exchange flow paths 140A, 140B allow air 142 (an example of the "heat medium" of the present invention) that is heated or cooled by heat exchange with the heat absorption and dissipation unit 110 to flow therethrough. More specifically, the heating heat exchange flow path 140A is configured to allow the air 142 heated by heat exchange with the heat absorption and dissipation unit 110 to flow therethrough. On the other hand, the cooling heat exchange flow path 140B is configured to allow the air 142 cooled by heat exchange with the heat absorption and dissipation unit 110 to flow therethrough.

[0013] The medium pressure adjusting means 200 is configured to adjust the pressure of the medium (water) inside the housing 120 by controlling the amount of the medium (water) inside the housing 120. The medium flow path 220 is connected to the interior of the housing 120. When it is desired to increase the pressure of the medium (water) inside the housing 120, the pressurizing pump 232 operates to supply the medium (water) from the medium tank 210 to the housing 120 through the medium flow path 220. On the other hand, when it is desired to reduce the pressure of the medium (water) inside the housing 120, the pressure reducing pump 234 operates to recover the medium (water) from the housing 120 to the medium tank 210 through the medium flow path 220.

[0014] Referring again to FIG. 1, the heat exchange device 10 according to the present embodiment includes a plurality of heat exchange units 100 as described above, to which the medium flow paths 220 shown in FIG. 2 are respectively connected, and the respective medium flow paths 220 are connected to each other and to the medium tank 210. Thereby, the pressure of the medium (water) inside the casing 120 described above can be adjusted individually for each of the plurality of heat exchange units 100. Further, the heating heat exchange flow path 140A and the cooling heat exchange flow path 140B shown in FIG. 2 are also connected to the plurality of heat exchange units 100, respectively. The respective heating heat exchange flow paths 140A are connected to each other, with the upstream side thereof connected to the air inlet 150 and the downstream side thereof connected to the air outlet 160. Similarly, the respective cooling heat exchange flow paths 140B are connected to each other, with the upstream side thereof connected to the air inlet 150 and the downstream side thereof connected to the air outlet 160.

[0015] (Heat absorbing and generating part) The heat absorbing and generating part 110 includes a porous material 112 whose pore diameter changes in response to an external stimulus, and a medium that is detachably adsorbed on the pore walls of the porous material 112. The heat absorbing and generating part 110 may be either a heat absorbing and generating material that absorbs heat as the pore diameter shrinks and generates heat as the pore diameter expands, or a heat absorbing and generating material that generates heat as the pore diameter shrinks and absorbs heat as the pore diameter expands.

[0016] The porous material 112 included in the heat absorbing and generating part 110 is not particularly limited as long as its pore diameter changes in response to a light stimulus. In the following, a case where a porous material having a porous body and a photoisomerization layer containing a photoisomerizable compound formed on the surfaces of the pores of the porous body is included as an example of the porous material whose pore diameter changes in response to a light stimulus will be described. The porous material is, for example, a material whose pore diameter changes reversibly by two types of light stimuli with different wavelengths.

[0017] The porous material is not particularly limited as long as it can adsorb and desorb a medium within its pores, but it is preferably a nanoporous material. "Nanoporous" means having multiple nanoscale pores. Nanoscale pores are preferably micropores or mesopores with a diameter of 0.5 to 100 nm, more preferably 0.7 to 50 nm, and even more preferably 0.7 to 6 nm. The IUPAC (International Union of Pure and Applied Chemistry) defines pores with a diameter of 2 nm or less as micropores, pores with a diameter of 2 to 50 nm as mesopores, and pores with a diameter of 50 nm or more as macropores.

[0018] In particular, it is preferable to use a mesoporous material having mesopores with a diameter of 2 to 50 nm as the porous body. The material of the porous body is not particularly limited, and examples include silica and alumina, but silica is preferred. In particular, it is preferable to use mesoporous silica as the porous body.

[0019] Mesoporous silica is a material made of silicon dioxide (silica) that has uniform and regular mesopores with a diameter of 2 to 50 nm. In the preparation of mesoporous silica, surfactant micelles are generally used as a template (structure directing agent), and the micelles are coated with silica components to form a regular silica skeleton. Further calcination removes the internal surfactant, leaving only the silica skeleton and forming regular mesopores. Various types have been synthesized by changing the type of surfactant, and the MCM series and SBA series are known. For example, MCM-41, aluminosilicate MCM-41, HMS, MCM-48, SBA-15, SBA-16, FSM-16, etc. can be cited. Commercially available mesoporous silica may also be used.

[0020] The pore size (average pore size) of mesoporous silica is not particularly limited, but is preferably 2 to 10 nm, and more preferably 2 to 5 nm. The shape and pore size (average pore size) of porous materials such as mesoporous silica can be confirmed by transmission electron microscopy (TEM) observation of the surface and cross-section of a thin film containing the porous material. The pore size (average pore size) of porous materials such as mesoporous silica may also be determined by nitrogen adsorption / desorption measurement. The BET specific surface area of ​​mesoporous silica is not particularly limited, but for example, 200 to 2500 m². 2 The value is / g. The pore volume (total pore volume) of mesoporous silica is not particularly limited, but for example, 0.2-4 cm³ is also acceptable. 3 The value is / g, preferably 0.2-1cm 3 The value is / g. The BET specific surface area and pore volume of porous materials such as mesoporous silica can be determined by nitrogen adsorption / desorption measurement. Mesoporous silica may also have surface-modified pore walls.

[0021] In this embodiment of the heat exchanger, it is preferable that the porous material has an optical isomerization layer containing a photoisomerization compound formed on the surface of the pores of the porous body. This makes it possible to more efficiently induce changes in pore size due to light stimulation. Therefore, the effects of the present invention can be obtained even more significantly. The means for forming the photoisomerization layer containing the photoisomerization compound are not particularly limited. For example, an optical isomerization layer can be formed by adsorbing or binding the photoisomerization compound to the surface of the pore walls of the porous body. In this case, the means for adsorbing or binding the photoisomerization compound are also not particularly limited. For example, the photoisomerization compound can be physically adsorbed onto the surface of the pores (the surface of the pore walls) of a mesoporous silica mesoporous body by methods such as solution impregnation or vacuum impregnation of the photoisomerization compound into a porous body such as mesoporous silica. Alternatively, the photoisomerization compound can be chemically bound to the surface of the pores of the pore wall porous body using a silane coupling agent or the like. Here, the ratio of the surface area volume of the surface on which the photoisomerized compound is adsorbed within the pores to the total surface area volume of the pores in the porous material is not particularly limited as long as it is greater than 0 and less than 1. The above ratio is preferably 0.1 to 0.9, more preferably 0.2 to 0.8, even more preferably 0.3 to 0.7, and even more preferably 0.4 to 0.6 when no medium is adsorbed. Within this range, the heat exchange efficiency can be further improved. The above ratio can be estimated by measuring the amount of nitrogen adsorbed on the porous material before and after the adsorption of the photoisomerized compound using the method described in the following examples for nitrogen adsorption and desorption measurement.

[0022] Photoisomerized compounds undergo stereoisomerization or structural isomerization (cis-trans isomerization, photo-ring opening reaction, etc.) upon light irradiation. Examples of photoisomerized compounds include compounds having an azobenzene structure (azobenzene compounds), compounds having a spiropyran structure, compounds having a stilbene structure, and compounds having a diarylethene structure. Of these, compounds having an azobenzene structure (azobenzene compounds) are preferred, and azobenzene is particularly preferred.

[0023] Azobenzene compounds isomerize from the trans isomer to the cis isomer upon irradiation with ultraviolet light, and from the cis isomer to the trans isomer upon irradiation with visible light. For example, in the case of azobenzene, photoisomerization occurs as shown in the following formula.

[0024] [ka]

[0025] Examples of media include water or alcohol. Examples of alcohols include methanol or ethanol. The media can be a fluid medium, that is, a liquid, a gas, or a mixture of liquid and gas.

[0026] Figure 3 schematically shows how, in a heat exchanger according to one embodiment of the present invention, the pore size of a porous material changes due to light stimulation, and consequently, a medium is adsorbed and desorbed onto the porous material. As shown in Figure 3(a), in the porous material 1, azobenzene, a photoisomerized compound, is adsorbed in a stable trans state on the surface of the inner wall 7 of the pores 4 in the porous body 2 with pore size D, and the pore size of the porous material 1 becomes B. When the medium 3 is introduced into the pores 4 of the porous material 1 as shown by the arrows, the medium 3 is adsorbed onto the inner wall 7 of the pores 4 in a liquid state, forming a meniscus 5. When ultraviolet light (UV) is irradiated onto the porous material 1, as shown in Figure 3(b), azobenzene is photoisomerized into the cis state. However, since the molecular length Lc of the cis state is smaller than the molecular length Lt of the trans state, the pore size A of the porous material 1 becomes larger than the pore size B before UV irradiation. Consequently, the meniscus of the adsorbed medium 3 collapses, and the medium 3 vaporizes and desorbs as shown by the arrows. Furthermore, when irradiated with visible light (Vis), azobenzene photoisomerizes from its cis isomer to its trans isomer, reducing its pore size to form B, which can adsorb medium 3. In this case, if medium 3 is a refrigerant such as water or alcohol, the heat-absorbing and heat-absorbing portion generates heat as the medium is adsorbed and absorbs heat as the medium is desorbed.

[0027] (Optical stimulation input unit) The specific form of the photostimulation input unit is not particularly limited and can be designed according to the type of porous material and photoisomerized compound. In a preferred embodiment, the photostimulation includes two or more photostimuli with different wavelengths. This makes it easier to control the pore size of the porous material and can improve the endothermic output. The photostimulation input unit that provides the photostimulation is, for example, a light source. The light source is not particularly limited and known light sources such as monochromatic lasers, light-emitting diodes (LEDs), low-pressure mercury lamps, high-pressure mercury lamps, xenon lamps, and metal halide lamps can be used. The wavelength of the irradiated light is also not particularly limited and can be set according to the type of photoisomerized compound. For example, ultraviolet light in the range of 280 to 400 nm and visible light in the range of 405 to 600 nm can be used in combination. The amount of irradiated light is also not particularly limited and can be set as appropriate.

[0028] In the embodiment shown in Figure 2, the visible light irradiation device 130A and the ultraviolet light irradiation device 130B, which are the optical stimulation input units, are located inside the housing 120. However, the position of the optical stimulation input units is not particularly limited. For example, the optical stimulation input units may be located outside the housing 120. If the optical stimulation input units are located outside the housing 120, it is preferable to provide light-transmitting parts (not shown), such as windows or slits, on the walls of the housing 120 to secure the optical path.

[0029] (Detention area) The materials used to constitute the housing (the casing 120 shown in Figure 2) are not particularly limited, but high thermal conductivity materials such as metals can be used. Among these, aluminum, iron, nickel, gold, silver, copper, alloys thereof, and stainless steel can be preferably used.

[0030] Preferably, the inner wall of the containment section reflects incident light as a photostimulus. In this way, incident light that has passed through the porous material can be reflected by the inner wall located in the extension of the incident light and reintroduced into the porous material, thus efficiently utilizing the incident light. As a result, the efficiency of heat exchange can be improved. Preferably, the inner wall of the containment section has a reflectance of 70% or more to incident light, and more preferably 80% or more. For example, aluminum has a reflectance of 80% or more in the wavelength range of 310 to 800 nm, and silver has a reflectance of 80% or more in the wavelength range of 360 to 800 nm. High efficiency can be achieved by using such materials for the inner wall of the containment section.

[0031] In a preferred embodiment, the external stimuli are two types of light stimuli with wavelengths λ1 and λ2, respectively. When the reflectance of the inner wall of the housing for light of wavelength λ1 is Rλ1 and the reflectance for light of wavelength λ2 is Rλ2, the housing is a sealed container in which the reflectance of the inner wall along the extension of the incident light of wavelength λ1 satisfies Rλ1 ≥ Rλ2, and the reflectance of the inner wall along the extension of the incident light of wavelength λ2 satisfies Rλ2 ≥ Rλ1. This allows for more efficient use of each type of light in both endothermic and exothermic reactions. Therefore, the efficiency of the heat exchanger can be further improved.

[0032] Furthermore, it is preferable that irregularities are formed on the surface of the inner wall of the housing, which lies in the extension of the incident light. This allows the incident light to be diffusely reflected off the surface of the inner wall, thereby improving efficiency. If the external stimuli are two or more types of light stimuli with different wavelengths, it is even more preferable that irregularities are formed on the surface of the inner wall, which lies in the extension of each incident light.

[0033] In one embodiment, the surface of the inner wall of the housing, which lies in the extension of the incident light, is convex, like the surface of a convex lens. Preferably, the center of the inner wall is located in the extension of the incident light, and the center of the inner wall is convex. As a result, a portion of the incident light can pass through the porous material and be reflected and diffused by the convex surface, thereby increasing the area of ​​the region illuminated by light when it enters the porous material again. As a result, higher efficiency can be achieved. When the light stimuli are two types of light stimuli with different wavelengths, the above configuration is preferable for each incident light (light stimuli). In another embodiment, a concave light-transmitting material, such as a concave lens, may be placed between the light stimulus input unit and the porous material. As a result, the incident light as a light stimulus is diffused, and the area of ​​the region illuminated by light when it enters the porous material can be increased. As a result, higher efficiency can be achieved. Here, the concave light-transmitting material only needs to be in the optical path of the incident light, and may be placed inside the housing or outside the housing. Also, when the light stimuli are two types of light stimuli with different wavelengths, the above configuration is preferable for each incident light (light stimuli).

[0034] In one embodiment, the surface of the inner wall of the housing, which lies in the extension of the incident light, is concave, like the surface of a concave lens. Preferably, the center of the inner wall is located in the extension of the incident light, and the center of the inner wall is concave. As a result, a portion of the incident light can pass through the porous material, be reflected by the concave surface, and be focused into the porous material before being re-entered into the porous material. Therefore, the energy density of the irradiated light increases, and efficiency can be improved. When the light stimuli are two types of light stimuli with different wavelengths, the above configuration is preferable for each incident light (light stimuli). In another embodiment, a convex light-transmitting material, such as a convex lens, may be placed between the light stimulus input unit and the porous material. As a result, the incident light as a light stimulus is focused into the porous material, increasing the energy density of the irradiated light and improving efficiency. Here, the convex light-transmitting material only needs to be in the optical path of the incident light, and may be placed inside or outside the housing. Also, when the light stimuli are two types of light stimuli with different wavelengths, the above configuration is preferable for each incident light (light stimuli).

[0035] (Heat exchange channel) The heat exchange channel is not particularly limited as long as it can circulate a heat transfer medium that is heated or cooled by heat exchange with the heat absorption / cooling section 110 housed in the housing, and can be provided to penetrate the interior of the housing. In the embodiments shown in Figures 1 and 2, the heating heat exchange channel 140A and the cooling heat exchange channel 140B are provided to penetrate the interior of the housing that constitutes each heat exchange unit 100. With this configuration, it is not necessary to use the heat exchange channel used to heat (or cool) the heat transfer medium (air) to cool (or heat) the heat transfer medium (air) afterward. Therefore, the influence of residual heat or cold in the piping and valves constituting the channel on the heat transfer medium that circulates thereafter can be reduced, and the efficiency of heat exchange can be improved. In short, it is possible to extract heat and cold separately and with high efficiency.

[0036] (Means for adjusting media pressure) The medium pressure adjustment means is for adjusting the pressure of the medium (water) inside the containment by controlling the amount of medium (water) inside the containment. When the pressurizing pump is activated and the medium (water) is supplied from the medium tank to the containment through the medium channel, the pressure of the medium (water) inside the containment increases. On the other hand, when the depressurizing pump is activated and the medium (water) is recovered from the containment to the medium tank through the medium channel, the pressure of the medium (water) inside the containment decreases. By adjusting the pressure of the medium in the containment in addition to applying or stopping light stimulation, the adsorption and desorption of the medium can be performed more efficiently, and the heat absorption and heating performance can be further improved.

[0037] (Operation of the heat exchanger) Next, we will explain the operation of the heat exchange device. Here, we will first explain using an example where the operation of heating and then cooling a heat transfer medium (air) is repeated in one heat exchange unit 100.

[0038] Figure 4 is an explanatory diagram illustrating one cycle in which the heat exchange unit 100 returns to its original state after going through an exothermic process (which can heat the heat transfer medium) and an endothermic process (which can cool the heat transfer medium). This cycle begins when the acquisition of cold energy (cooling) is completed. First, visible light is irradiated onto the heat absorption and exothermic section from before the completion of the acquisition of cold energy (cooling) to after the start of the cycle. This causes the photoisomerized compound (azobenzene) to be trans-converted, reducing the pore size of the porous material (step (F)). Next, in the middle of step (F), a pressurizing pump is activated to start supplying the medium (water vapor) into the containment section, increasing the partial pressure of the medium (water vapor) inside the containment section (step (A)). At this time, it is preferable to supply an amount of medium (water vapor) that exceeds the saturation water vapor amount. Here, since the pore size of the porous material has been reduced by step (F), the partial pressure of the medium (water vapor) inside the containment section increases, causing the medium (water) to adsorb onto the inner wall of the pores of the porous material. During this process, the latent heat of adsorption causes the heat-absorbing and heat-generating section to heat up, and the temperature of the heat-absorbing and heat-generating section rises (heat-generating process). At the timing of this heat-generating process, a heat transfer medium (air) is circulated through the heat exchange channel, which heats the heat transfer medium (air) and raises its temperature.

[0039] After the heat generation process described above, a depressurizing pump is activated to degas the medium (water vapor) from inside the containment section, thereby reducing the partial pressure of the medium (water vapor) inside the containment section (step (B)). At this time, it is preferable that the partial pressure of the medium (water vapor) inside the containment section be less than the saturated water vapor pressure, and may be 80% or less, 50% or less, 30% or less, or 10% or less of the saturated water vapor pressure. Subsequently, ultraviolet light is irradiated onto the heat-absorbing and heat-generating section during step (B). This causes the photoisomerized compound (azobenzene) to undergo cis-conjugation, thereby expanding the pore size of the porous material (step (E)). Since heat is also supplied during ultraviolet light irradiation, it is preferable that the irradiation time of ultraviolet light be shorter than the irradiation time of visible light, and may be 80% or less, 50% or less, 30% or less, or 10% or less of the irradiation time of visible light. When the meniscus collapses due to the expansion of the pore size of the porous material, the medium (water) adsorbed on the inner wall of the pores of the porous material is desorbed (evaporated). At this time, the partial pressure of the medium (water) inside the containment section decreases, thus promoting desorption (evaporation). The latent heat of vaporization generated at this time causes the heat-absorbing and heat-generating section to absorb heat and generate cooling, and the temperature of the heat-absorbing and heat-generating section decreases (cooling process). By circulating a heat transfer medium (air) through the heat exchange channel at the timing of this cooling process, the heat transfer medium (air) is cooled and its temperature decreases. In this way, the heat exchange unit 100 returns to its original state after going through a heat-generating process (which can heat the heat transfer medium) and a heat-absorbing process (which can cool the heat transfer medium).

[0040] Utilizing the cycle of such heat exchange units, the heat exchange apparatus 10 according to this embodiment comprises a plurality of heat exchange units 100, and is configured to circulate air, which is the heat transfer medium, through the heat exchange channels 140A and 140B according to the timing of heat absorption and heat generation in the respective heat absorption and heat generation sections 110 of the plurality of heat exchange units 100. Below, an example of control for switching each channel when continuously heating or cooling the heat transfer medium (air) using three of the plurality of heat exchange units 100 (heat exchange units U1, U2, U3...UN shown in Figure 1) that constitute the heat exchange apparatus 10 will be described.

[0041] Figure 5 is an explanatory diagram illustrating how control is implemented to switch between each flow path when continuously heating or cooling a heat transfer medium (air) using multiple heat exchange units U1, U2, and U3.

[0042] First, to continuously heat the heat transfer medium (air), one of the multiple heat exchange units U1, U2, and U3 is selected as the heat exchange unit capable of heating the heat transfer medium, located in the heat generation process shown in Figure 4 (for example, heat exchange unit U1 in the heating process (H1) shown in Figure 5). Next, valves (not shown) located upstream and downstream of the heating heat exchange channel 140A that constitutes the heat exchange unit U1 are opened, and the air 142 introduced from the air inlet 150 is circulated to the heating heat exchange channel 140A of the heat exchange unit U1. In this case, it is convenient to use valves that can branch the heat exchange channel according to the number of heat exchange units to be used (the same applies to the supply and recovery of the medium through the pressurizing pump 232 and the depressurizing pump 234). An example of such a valve is an eight-way valve. However, it is also possible to provide a valve individually for each channel and to control all valves by a control unit. By circulating the air 142 into the heating heat exchange channel 140A in this manner, the heated air 142 in the heat exchange unit U1 can be discharged from the air outlet 160. Subsequently, since the heat exchange unit U1 then moves to the cooling process, the valves located upstream and downstream of the heating heat exchange channel 140A that constitute the heat exchange unit U1 are closed. Next, the heat exchange unit U2 is operated so that the heating process begins at the same time that the heating process of the heat exchange unit U1 is completed. In the same manner as above, the valves (not shown) located upstream and downstream of the heating heat exchange channel 140A that constitute the heat exchange unit U2 are opened, and the air 142 introduced from the air inlet 150 is circulated into the heating heat exchange channel 140A of the heat exchange unit U2. This allows the heated air 142 in the heat exchange unit U1 to be discharged from the air outlet 160. The same operation can be repeated for the heat exchange unit U3. If there are N heat exchange units 100 (U1 to UN), the above operation may be repeated sequentially for each of the N heat exchange units 100, or, in some cases, several heat exchange units 100 may be selected, and the above operation may be repeated using only those selected heat exchange units 100. In any case, it becomes possible to heat the air 142 for a desired amount of time.

[0043] On the other hand, to continuously cool the heat transfer medium (air), first, from among the multiple heat exchange units U1, U2, and U3, the heat exchange unit located in the cooling process shown in Figure 4 (for example, heat exchange unit U1 in the cooling process (C1) shown in Figure 5) is selected as the heat exchange unit capable of cooling the heat transfer medium. Next, valves (not shown) located upstream and downstream of the cooling heat exchange channel 140B that constitutes the heat exchange unit U1 are opened, and the air 142 introduced from the air inlet 150 is circulated to the cooling heat exchange channel 140B of the heat exchange unit U1. This allows the air 142 cooled in the heat exchange unit U1 to be discharged from the air outlet 160. By continuously repeating this operation using multiple heat exchange units 100 with staggered timings, it is possible to cool the air 142 for a desired period of time, similar to the above. In this way, by implementing the control shown in Figure 5, the effect of residual heat is eliminated, and the occurrence of time differences in temperature changes and heat losses caused by the heat capacity of equipment such as piping can be prevented. As a result, the heat transfer medium (air) can be heated or cooled with high efficiency.

[0044] Although one embodiment of the heat exchange device 10 according to one aspect of the present invention has been described above, the present invention is not limited to the configuration described in the above-mentioned embodiment, and can be modified as appropriate based on the description of the claims.

[0045] For example, as a modified example of the heat-absorbing and heat-generating section, the heat-absorbing and heat-generating section may include the porous material described above, which is supported on the outer surface of a carrier having hollow channels inside. In this case, it is preferable that the channels of the carrier constitute a part of the heat exchange channel.

[0046] Figure 6 shows an example of a modified heat-absorbing and heat-generating section. Figure 6(a) is a schematic diagram showing the outline of the heat-absorbing and heat-generating section, and Figure 6(b) is a cross-sectional view of the hollow channel inside the carrier along a plane perpendicular to the flow direction of the heat transfer medium (air). As shown in Figures 6(a) and 6(b), the heat-absorbing and heat-generating section 110 according to this modified example includes a carrier 114. The carrier 114 has a highly branched hollow channel 116 inside. A porous material 112 is supported on the outer surface of the carrier 114. Here, the porous material 112 is, for example, obtained by adsorbing a photoisomerized compound onto the surface of the pore wall of the mesoporous silica described above by physical adsorption or the like.

[0047] A portion of the hollow channel inside the carrier 114 is connected to an air inlet (not shown) and a heat exchange channel 140 through which air 142 flows (for example, a heating heat exchange channel 140A or a cooling heat exchange channel 140B). On the other hand, another portion of the hollow channel inside the carrier 114 (preferably the portion furthest from the above-mentioned connection) is connected to an air outlet (not shown) and a heat exchange channel 140 through which air 142 flows (for example, a heating heat exchange channel 140A or a cooling heat exchange channel 140B). With this configuration, the air 142, which is the heat transfer medium, can be efficiently heated or cooled by the same mechanism as described above. Furthermore, depending on the design of the shape of the carrier, the surface area of ​​the outer surface and the channel length can be increased, making it possible to further improve the efficiency of heat exchange. A carrier having a hollow channel inside as shown in Figure 6 can be manufactured, for example, using an additive manufacturing device such as a 3D printer.

[0048] <Examples of application> The heat exchange device 10 described above can be applied, for example, to an air conditioning system (vehicle air conditioning system) installed in a vehicle.

[0049] Furthermore, the following items are also included within the scope of the present invention: Item 1: A porous material whose pore size changes upon light stimulation, and an absorbent / heat-generating section including a medium that adsorbs and desorbs onto the porous material, A housing section for housing the heat-absorbing and heat-generating section, A light stimulation input unit that applies the light stimulation to the porous material, A heat exchange channel is provided so as to penetrate the interior of the housing section, through which a heat transfer medium is heated or cooled by heat exchange with the heat absorption / heating section, A heat exchange device comprising a heat exchange unit; Item 2: The heat exchanger according to Item 1, further comprising a medium pressure adjusting means connected to the housing and for adjusting the pressure of the medium inside the housing by controlling the amount of the medium inside the housing; Item 3: comprising a plurality of the heat exchange units, A heat exchange apparatus according to claim 1 or 2, configured to circulate the heat transfer medium through the heat exchange channel in accordance with the timing of heat absorption and heat generation in each of the heat absorption and heat generation sections of the plurality of heat exchange units; Item 4: The heat exchange channel included in each of the plurality of heat exchange units is A heating heat exchange channel for circulating the heat transfer medium, which is heated by heat exchange with the heat absorption and heating section, A cooling heat exchange channel for circulating the heat transfer medium, which is cooled by heat exchange with the heat absorption / heating section, A heat exchanger according to any one of items 1 to 3, comprising: Item 5: The heat-absorbing and heat-generating portion includes the porous material supported on the outer surface of a carrier having a hollow channel inside, A heat exchange apparatus according to any one of claims 1 to 4, wherein the flow path of the carrier constitutes a part of the heat exchange flow path; Item 6: The heat exchange apparatus according to any one of items 1 to 5, wherein the light stimulation includes two or more light stimulations of different wavelengths; Item 7: A vehicle air conditioning system using a heat exchanger as described in any of items 1 to 6. [Examples]

[0050] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0051] [Example 1] As a porous body, MCM-41 (manufactured by MERCK Sigma-Aldrich, 643645), which is mesoporous silica, was prepared. Observation by TEM revealed that the mesoporous silica had a hexagonal structure and had one-dimensional pores with a pore diameter of 3.78 nm. The pore volume of the mesoporous silica was 0.621 cm 3 / g. Azobenzene, which is a photoisomerizable compound, was introduced into the pores of this mesoporous silica using a solution introduction method. Specifically, first, an ethanol solution of azobenzene was prepared. The solution concentration was adjusted so that φ, which will be described later, AZO was 0.48. Next, the dehydrated mesoporous silica was weighed to determine the mass m MCM . To the vial containing the dehydrated mesoporous silica, the ethanol solution of azobenzene prepared above was added, and the vial was sealed and allowed to stand in a dark room for 24 hours. This was taken out of the dark room and dried in a fume hood. The mass of this sample was measured, and m MCM was subtracted from the mass at this time to obtain the mass m Azo of the photoisomerizable compound filled in the pores of the mesoporous silica. In this way, a porous material having a photoisomerizable layer containing azobenzene on the surface of the pores of the mesoporous silica was obtained.

[0052] In addition, φ AZO (the ratio of the volume of the photoisomerizable compound present in the pores to the pore volume of the porous body) was calculated according to the following formula:

[0053] [Formula]

[0054] In the above formula, m MCM is the mass of the mesoporous silica, m Azo is the mass of the photoisomerizable compound filled in the pores of the mesoporous silica, V MCM is the pore volume of the mesoporous silica, and ρ AZO is the bulk density of the photoisomerizable compound. In addition, the pore volume V MCM of the mesoporous silica was calculated from the results of nitrogen adsorption measurement.

[0055] Nitrogen adsorption / desorption isotherms were measured for the obtained porous material by varying the presence or absence of ultraviolet light irradiation. A High Power xenon lamp light source MAX-301 manufactured by Asahi Spectroscopic Co., Ltd. was used as the light source. The porous material was irradiated with ultraviolet light using a UV mirror module, bandpass filter, and light guide rod attached to the xenon lamp. Nitrogen adsorption / desorption isotherms were measured using a volumetric adsorption isotherm measuring device. Figure 7 shows the nitrogen adsorption / desorption isotherms for cases where ultraviolet light irradiation was not performed during either the adsorption or desorption process (OFF-OFF), when ultraviolet light irradiation was performed during both the adsorption and desorption processes (ON-ON), and when ultraviolet light irradiation was performed only during the desorption process after saturated adsorption (OFF-ON). In Figure 7, filled plots represent the desorption process, and open plots represent the adsorption process. In both cases—when UV light irradiation was not performed during both the adsorption and desorption processes (OFF-OFF) and when UV light irradiation was performed during both processes (ON-ON)—they exhibited type IV isotherms with hysteresis characteristic of mesoporous silica.

[0056] On the other hand, when ultraviolet light irradiation was performed only during the desorption process after saturated adsorption (OFF-ON), a rapid desorption occurred after ultraviolet light irradiation, as shown by the arrow in Figure 7, followed by a gradual desorption process, resulting in a unique isotherm. This rapid desorption after ultraviolet light irradiation is thought to be caused by the photoisomerization of azobenzene in the pores from the trans isomer to the cis isomer due to ultraviolet light irradiation. As a result, the pore size expanded, stretching the nitrogen meniscus, which was stable during saturated adsorption, and causing it to become unstable and collapse. Furthermore, from the amount of nitrogen desorbed due to the rapid desorption caused by ultraviolet light irradiation, as shown by the arrow in Figure 7, the pore size expansion due to photoisomerization was estimated to be about 1.1 nm.

[0057] Furthermore, the total adsorption amount was greater when UV light irradiation was performed during both the adsorption and desorption processes (ON-ON) than when UV light irradiation was not performed during both processes (OFF-OFF). When azobenzene was irradiated with UV light, it existed as the cis isomer, and since the molecular length of the cis isomer is approximately 0.65 nm, which is smaller than the molecular length of the trans isomer (approximately 1.2 nm), it is thought that the pore size of the porous material expanded, leading to an increase in nitrogen adsorption.

[0058] Table 1 below shows the estimated heat generation when azobenzene adsorbed on mesoporous silica was in the cis isomer (large pore size) and when it was in the trans isomer (small pore size). From the results in Figure 7, the amount of nitrogen adsorbed per unit mass of mesoporous silica was determined when azobenzene was in the cis and trans isomers. From this value, the volume of nitrogen adsorbed per unit mass of mesoporous silica was determined and used as the pore volume. The amount of methanol was calculated by multiplying the pore volume by the density of methanol. The amount of heat generated was calculated by multiplying the amount of methanol by the latent heat of vaporization of methanol.

[0059] [Table 1]

[0060] Thus, it was confirmed that the porous material described above changes in pore size upon irradiation with ultraviolet light, allowing the adsorbed medium to desorb. Furthermore, it was found that a sufficient amount of heat can be generated due to the heat of adsorption of the medium. Therefore, it is understood that such a porous material can reversibly adsorb and desorb a medium to generate heat. Consequently, by using it as the heat absorption and heat generation section of a heat exchanger, it is possible to miniaturize the heat exchanger and improve the energy consumption efficiency. [Explanation of Symbols]

[0061] 10 heat exchange equipment, 100 heat exchange units, 110 Heat-absorbing and heat-generating section, 112 porous materials, 114 carriers, 116 channels, 120 enclosure (housing section), 130A Visible light irradiation device (light stimulation input unit), 130B UV light irradiation device (photostimulation input unit), 140 heat exchange channel, 140A Heat exchange channel for heating (heat exchange channel), 140B Cooling heat exchange channel (heat exchange channel), 150 air inlet, 160 air outlets, 200 means for adjusting media pressure, 210 media tanks, 220 medium flow path, 232 pressure pump, 234. Pressure reducing pump.

Claims

1. A porous material whose pore size changes upon light stimulation, and an absorbent / heat-generating section containing a medium that adsorbs and desorbs onto the porous material, A housing section for housing the heat-absorbing and heat-generating section, A light stimulation input unit that applies the light stimulation to the porous material, A heat exchange channel is provided so as to penetrate the interior of the housing, through which a heat transfer medium, which is heated or cooled by heat exchange with the heat absorption / heating section, is circulated. A heat exchange device comprising a heat exchange unit including a heat exchange unit.

2. The heat exchanger according to claim 1, further comprising a medium pressure adjusting means connected to the housing section for adjusting the pressure of the medium inside the housing section by controlling the amount of the medium inside the housing section.

3. The system comprises multiple heat exchange units, The heat exchange apparatus according to claim 1 or 2, configured to circulate the heat transfer medium through the heat exchange channel in accordance with the timing of heat absorption and heat generation in each of the plurality of heat exchange units.

4. Each of the aforementioned plurality of heat exchange units contains the heat exchange channel, A heating heat exchange channel for circulating the heat transfer medium, which is heated by heat exchange with the heat absorption and heating section, A cooling heat exchange channel for circulating the heat transfer medium, which is cooled by heat exchange with the heat absorption / heating section, The heat exchange apparatus according to claim 3, comprising:

5. The heat-absorbing and heat-generating portion includes the porous material supported on the outer surface of a carrier having a hollow channel inside, The heat exchange apparatus according to claim 1 or 2, wherein the flow path of the carrier constitutes a part of the heat exchange flow path.

6. The heat exchange apparatus according to claim 1 or 2, wherein the light stimulation includes two or more light stimulations with different wavelengths.

7. A vehicle air conditioning system using the heat exchanger described in claim 1 or 2.

Images