JP7632247B2 - Adsorption device and adsorption multi-stage heat pump - Google Patents

Description

This disclosure relates to an adsorption device and an adsorption-type multi-stage heat pump.

Conventionally, as an adsorption heat pump, a multi-stage adsorption heat pump is known that includes an evaporator that evaporates the adsorbate and a number of adsorbers connected in series to the evaporator (see, for example, Patent Document 1). In such an adsorption multi-stage heat pump, in addition to generating cold energy in the evaporator, when the first-stage adsorber connected to the evaporator is connected to the second-stage adsorber and depressurized, the adsorbate is desorbed in the first-stage adsorber and cold energy is generated, thereby making it possible to increase the efficiency of cold energy generation in the heat pump.

JP 2016-11822 A

However, for example, if the operating pressure when the adsorbate is desorbed in the first-stage adsorber and adsorbed in the second-stage adsorber is relatively low, the diffusion of the adsorbate vapor in the first-stage adsorber may be slow, and the desorption of the adsorbate and the generation of cold heat may be suppressed. Even if an attempt is made to increase the surface area of the adsorbent in the first-stage adsorber in order to increase the diffusivity of the adsorbate vapor in the first-stage adsorber, if this results in suppression of heat transfer in the adsorbent, the desorption of the adsorbate may be suppressed and the efficiency of cold heat generation may not be sufficiently improved. Therefore, further improvement of the configuration of the first-stage adsorber has been desired in order to increase the efficiency of desorption of the adsorbent and cold heat generation in the first-stage adsorber.

The present disclosure can be realized in the following forms.
(1) According to one aspect of the present disclosure, in an adsorption-type multi-stage heat pump in which a plurality of adsorbers are connected in series to an evaporator, a first-stage adsorber is provided that is connected to the evaporator. This adsorber includes a cylindrical heat transfer tube through which a heat medium flows, and an adsorbent layer in which a plurality of wire layers are stacked on an outer wall of the heat transfer tube, the wire layers being layers in which linear members containing an adsorbent that adsorbs and desorbs an adsorbate are arranged in a certain direction, and the wire layers adjacent to each other in the stacking direction have different angles at which the linear members are arranged and cross each other.
According to this type of adsorber, since the entire adsorbent layer is formed in a mesh shape, the diffusion distance of the adsorbate in the adsorbent of the adsorbent layer can be shortened to increase the diffusion rate of the adsorbate and the utilization efficiency of the adsorbent in the adsorbent layer can be increased. Also, since the adsorbent layer is arranged in layers on the outer wall of the cylindrical heat transfer tube, the efficiency of heat transfer from the heat transfer tube to the adsorbent layer can be increased. Therefore, when the adsorber is used as the first stage adsorber of an adsorption-type multistage heat pump, the efficiency of cold generation can be increased when the adsorbate is desorbed in the adsorber.
(2) In the adsorber of the above embodiment, the adsorbent may be an aluminum-containing metal organic framework (Al-MOF). With this configuration, by using Al-MOF as the adsorbent in the first stage of the adsorption multistage heat pump, it becomes easier to increase the efficiency of cold heat generation in the multistage heat pump including the adsorber.
(3) In the adsorber of the above embodiment, the wire diameter w of the linear member may be greater than 0.05 mm and less than 0.6 mm, and the thickness H of the adsorbent layer may be greater than 0.5 mm and less than 4.0 mm. With this configuration, when the adsorber is used as a first-stage adsorber of a multi-stage heat pump, the efficiency of cold generation during desorption of the adsorbate in the first-stage adsorber can be improved. In other words, the diffusion rate of the adsorbate vapor in the adsorbent and the heat transfer in the adsorbent can be both achieved, thereby improving the efficiency of desorption in the adsorbent.
(4) In the adsorber of the above embodiment, the wire diameter w of the linear member may be greater than 0.1 mm and less than 0.4 mm. With this configuration, when the adsorber is used as a first-stage adsorber of a multi-stage heat pump, the efficiency of cold generation during adsorption and desorption of the adsorbate in the first-stage adsorber can be further improved.
(5) In the adsorber of the above embodiment, the thickness H of the adsorbent layer may be greater than 0.8 mm and less than 3.0 mm. With this configuration, when the adsorber is used as a first-stage adsorber of a multi-stage heat pump, the efficiency of cold generation during the adsorption and desorption of the adsorbate in the first-stage adsorber can be further improved.
(6) According to another aspect of the present disclosure, there is provided an adsorption multistage heat pump in which a plurality of adsorbers are connected in series to an evaporator. This multistage adsorption heat pump includes the adsorber according to any one of (1) to (5) as a first stage adsorber connected to the evaporator. According to this aspect of the multistage adsorption heat pump, it is possible to increase the efficiency of cold heat generation using the heat pump.
The present disclosure may be realized in various forms other than those described above, for example, in the form of a method for manufacturing an adsorption device, a method for manufacturing an adsorption-type multi-stage heat pump including an adsorption device, or a method for controlling adsorption and desorption in an adsorption-type multi-stage heat pump.

FIG. 1 is an explanatory diagram showing a schematic configuration of a heat pump. FIG. 2 is an explanatory diagram illustrating a schematic configuration of a first suction unit; FIG. 2 is a perspective view showing a schematic configuration of a tubular module. FIG. 2 is a perspective view showing an outline of the external appearance of a tubular module. FIG. 4 is an explanatory diagram showing an enlarged view of a part of the tubular module. FIG. FIG. FIG. 2 is a contour map of output VCP versus wire diameter w and thickness H. FIG. 13 is an explanatory diagram showing the distribution of adsorption amounts 10 seconds after the start of desorption under condition a. FIG. 11 is an explanatory diagram showing the distribution of the amount of adsorption 10 seconds after the start of desorption under condition b. FIG. 11 is an explanatory diagram showing the distribution of the amount of adsorption 10 seconds after the start of desorption under condition c. FIG. 11 is an explanatory diagram showing the temperature distribution 10 seconds after the start of desorption under condition a. FIG. 11 is an explanatory diagram showing the temperature distribution 10 seconds after the start of desorption under condition b. FIG. 11 is an explanatory diagram showing the temperature distribution 10 seconds after the start of desorption under condition c. FIG. 2 is a contour map of output VCP versus wire diameter w and thickness H.

A. Heat Pump Configuration:
1 is an explanatory diagram showing a schematic configuration of a heat pump 10 according to the present embodiment. The heat pump 10 includes an evaporator 12, a condenser 18, and two adsorption units, a first adsorption unit 14 and a second adsorption unit 16, which are connected in parallel between the evaporator 12 and the condenser 18. The heat pump 10 is an adsorption-type multistage heat pump, and each of the first adsorption unit 14 and the second adsorption unit 16 includes an adsorption unit with multiple stages (two stages in the present embodiment).

The first adsorption unit 14 includes two adsorbers connected in series between the evaporator 12 and the condenser 18. Specifically, the first adsorption unit 14 includes a first adsorber 20, which is a first-stage adsorber connected to the evaporator 12, and a second adsorber 22, which is a second-stage adsorber connected to the first adsorber 20 and the condenser 18. The first adsorber 20 includes a reaction vessel 20a, an adsorbent housed in the reaction vessel 20a, and a heat medium flow path 20b through which a heat medium flows inside the reaction vessel 20a, and the second adsorber 22 includes a reaction vessel 22a, an adsorbent housed in the reaction vessel 22a, and a heat medium flow path 22b through which a heat medium flows inside the reaction vessel 22a. The first adsorber 20 and the second adsorber 22 include different types of adsorbents. The first adsorber 20 is also simply called an "adsorber". The adsorbent in the first adsorption device 20 is also called the "first adsorbent" or simply the "adsorbent", and the adsorbent in the second adsorption device 22 is also called the "second adsorbent". It is desirable for the first adsorbent to have a larger equilibrium adsorption amount difference in the range of operating pressures in the heat pump 10 (adsorption/desorption relative pressure range).

As a combination of the first adsorbent and the second adsorbent, for example, a combination of using an aluminum-containing metal organic framework (Al-MOF) as the first adsorbent and using zeolite 13X as the second adsorbent can be mentioned. In addition, a combination of using a zeolite-based adsorbent such as AQSOA-Z01, AQSOA-Z02, or AQSOA-Z05 ("AQSOA" is a registered trademark of Mitsubishi Plastics) as the first adsorbent and using Y-type zeolite as the second adsorbent can be mentioned. Alternatively, a combination of using zeolite B as the first adsorbent and zeolite D as the second adsorbent may be used. In particular, a configuration using Al-MOF (Metal-Organic Framework) as the first adsorbent and zeolite 13X as the second adsorbent is preferable. Since Al-MOF is generally desorbed under relatively low pressure conditions of 0.2 to 0.4 or less relative pressure, it is desirable as the first adsorbent provided in the first adsorber 20, which is the first stage adsorber. Al-MOF will be described later. Note that "relative pressure" refers to the ratio of the vapor pressure of the adsorbate when the adsorbent in the adsorber is in adsorption equilibrium to the saturated vapor pressure of the adsorbate.

However, the combination of the first adsorbent and the second adsorbent is not limited to the above combinations, since any combination that allows the adsorbate to move from the first adsorbent to the second adsorbent is possible as long as the relative pressure at which the first adsorbent is desorbable is greater than the relative pressure at which the second adsorbent is desorbable under temperature and relative pressure conditions that can be set in the heat pump 10. For example, it is desirable to use an adsorbent such as Al-MOF, AQSOA-Z01, AQSOA-Z02, or AQSOA-Z05, which has a characteristic that the adsorption amount rises at a specific relative pressure (the adsorption amount changes greatly over a narrow partial pressure range), as the first adsorbent. In such a case, the second adsorbent may be an adsorbent that exhibits an adsorption amount that allows the first adsorbent to adsorb the adsorbate desorbed at a relative pressure lower than the specific relative pressure.

Al-MOF (Metal-Organic Framework), which is preferably used as the first adsorbent, is a complex crystal obtained by utilizing the self-organization of aluminum ions and organic bridging ligands, and the metal and organic ligands interact to form a porous coordination network structure with a high surface area. Specific examples of Al-MOF are given below, but Al-MOFs that can be used as the first adsorbent are not limited to these.

An example of an Al-MOF that can be used as the first adsorbent is an ^adsorbent having Al ³⁺ and the following formula (I):

[In the formula, each R independently represents a hydrogen atom, an alkyl group, a hydroxyl group, or an alkoxy group.]
and a first ligand derived from at least one aromatic dicarboxylic acid selected from the group consisting of isophthalic acid and derivatives thereof represented by the following formula (II):

[In the formula, X represents a nitrogen atom, a sulfur atom, or an oxygen atom, and n is 2 or 3.]
and a second ligand derived from at least one heterocyclic dicarboxylic acid represented by the following formula:

Another example of an Al-MOF that can be used as the first adsorbent is a MOF that is composed of ^{Al 3+} , a first ligand derived from at least one aromatic dicarboxylic acid selected from the group consisting of isophthalic acid and its derivatives, which is coordinated to the Al 3+ , and a ligand represented by the following formula (III):

[In the formula, each X independently represents a hydrogen atom, an alkyl group, a hydroxyl group, or an alkoxy group, and n is 2 or 4.]
and a second ligand derived from at least one aliphatic dicarboxylic acid represented by the following formula:

Further, as another example of an Al-MOF that can be used as the first adsorbent, there is an Al- ^MOF having Al ³⁺ and a compound represented by the following formula (IV):

[In the formula, each R ¹ independently represents a hydrogen atom, an alkyl group which may have a substituent, a hydroxyl group, or an alkoxy group which may have a substituent.]
and a first ligand derived from at least one fumaric acid compound selected from the group consisting of fumaric acid and fumaric acid derivatives represented by the following formula (V):

[In the formula, each R ² independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms which may have a substituent, a hydroxyl group, or an alkoxy group having 1 to 3 carbon atoms which may have a substituent, and each R ³ independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a hydroxyl group, or an alkoxy group having 1 to 3 carbon atoms.]
and a second ligand derived from at least one aspartic acid compound selected from the group consisting of aspartic acid and aspartic acid derivatives represented by the following formula (I) and alkali metal salts thereof.

The adsorbate to be adsorbed and desorbed in the first adsorbent and the second adsorbent may be, for example, water, ammonia, methanol, or ethanol. Water and ammonia are desirable because they are adsorbed and desorbed to the adsorbent under the operating conditions (temperature and pressure) set by the heat pump 10 and are relatively inexpensive, with water being particularly desirable.

The first adsorption device 20 of this embodiment has a configuration that can particularly increase the efficiency of adsorption of the adsorbate. The detailed configuration of the first adsorption device 20 will be described later.

The heat pump 10 includes a pipe 21 that connects the evaporator 12 and the first adsorber 20, and the pipe 21 is provided with an on-off valve 21a. When the on-off valve 21a is opened, the adsorbate can be transferred from the evaporator 12 to the first adsorber 20. The heat pump 10 also includes a pipe 23 that connects the first adsorber 20 and the second adsorber 22, and the pipe 23 is provided with an on-off valve 23a. When the on-off valve 23a is opened, the adsorbate can be transferred from the first adsorber 20 to the second adsorber 22. The heat pump 10 also includes a pipe 24 that connects the second adsorber 22 and the condenser 18, and the pipe 24 is provided with an on-off valve 24a. When the on-off valve 24a is opened, the adsorbate can be transferred from the second adsorber 22 to the condenser 18.

The second suction portion 16 has a similar configuration to the first suction portion 14, and the common parts are given the same reference numbers.

The evaporator 12 includes a storage container 12a, an adsorbate stored in the storage container 12a, and a heat medium flow path 12b through which a heat medium flows to exchange heat with the adsorbate. In the evaporator 12, the adsorbate stored in the storage container 12a evaporates, and cold heat is generated by the latent heat of evaporation, and the generated cold heat is extracted from the evaporator 12 via the heat medium.

The condenser 18 is supplied with vapor of the adsorbate from the second adsorbent 22 and condenses the adsorbate. The heat pump 10 further includes a pipe 25 that connects the condenser 18 to the evaporator 12, and the pipe 25 is provided with an on-off valve 25a. When the on-off valve 25a is opened, the adsorbate condensed in the condenser 18 can move to the evaporator 12.

The heat pump 10 further includes a control unit (not shown). This control unit controls the switching of the operation modes of the heat pump 10 (processes including the first-stage adsorption process, the adsorption/desorption process, and the second-stage desorption process, which will be described later), including the control of each of the on-off valves described above.

B. Heat pump operation control:
In the heat pump 10, in the operation control related to cold energy generation, an operation control is performed in which a process including a first-stage adsorption process, an adsorption/desorption process, and a second-stage desorption process is repeatedly performed. Of the above-mentioned processes, the first-stage adsorption process and the adsorption/desorption process are processes for generating cold energy. The operation of each of these processes will be described in order below. As an example, FIG. 1 shows a state in which the first adsorption unit 20 of the first adsorption unit 14 is performing the first-stage adsorption process, the second adsorption unit 16 is performing the adsorption/desorption process, and the second adsorption unit 22 of the first adsorption unit 14 is performing the second-stage desorption process. In FIG. 1, the open-close valves represent an open state, and in the following description, the open-close valves other than the open-close valves specifically stated to be in an open state are closed.

In the first-stage adsorption process, as shown in the first adsorber 20 of the first adsorption section 14 in FIG. 1, the on-off valve 21a is opened, and the evaporator 12 and the first adsorber 20 are connected through the pipe 21. At this time, in the evaporator 12, a heat medium (e.g., 10 to 15°C) supplied from a low-temperature heat source (not shown) flows through the heat medium flow path 12b. Then, in the first adsorber 20, a heat medium (e.g., 30°C) supplied from a medium-temperature heat source (not shown) flows through the heat medium flow path 20b. Also, the on-off valve 23a is closed, and the connection between the first adsorber 20 and the second adsorber 22 is cut off. As a result, the adsorbate evaporates in the evaporator 12, and the evaporated adsorbate is adsorbed by the first adsorbent of the first adsorber 20. Then, as the adsorbate evaporates, cold heat is generated in the evaporator 12, and the generated cold heat is taken out through the heat medium in the heat medium flow path 12b.

In the adsorption/desorption process, as shown in the second adsorption section 16 in FIG. 1, the on-off valve 21a of the pipe 21 and the on-off valve 24a of the pipe 24 are closed to cut off the connection between the evaporator 12 and the first adsorption device 20, and the connection between the second adsorption device 22 and the condenser 18. The on-off valve 23a of the pipe 23 is opened to connect the first adsorption device 20 and the second adsorption device 22. At this time, in the first adsorption device 20, a heat medium (e.g., 10 to 15°C) supplied from a low-temperature heat source (not shown) flows through the heat medium flow path 20b. In the second adsorption device 22, a heat medium (e.g., 30°C) supplied from a medium-temperature heat source (not shown) flows through the heat medium flow path 22b. Under the pressure conditions (relative pressure) thus achieved, the adsorbate is desorbed by the first adsorbent of the first adsorber 20 based on the adsorption/desorption characteristics of the first adsorbent and the second adsorbent, and the desorbed adsorbate is adsorbed by the second adsorbent of the second adsorber 22. As the adsorbate is desorbed by the first adsorbent, cold heat is generated in the first adsorber 20, and the generated cold heat is extracted via the heat medium in the heat medium flow path 20b.

In the second-stage desorption process, as shown in the second adsorber 22 of the first adsorption section 14 in FIG. 1, the on-off valve 23a of the pipe 23 is closed to cut off the connection between the first adsorber 20 and the second adsorber 22. Also, the on-off valve 24a of the pipe 24 is opened to connect the second adsorber 22 and the condenser 18 through the pipe 24. At this time, in the second adsorber 22, a heat medium (e.g., 40 to 55°C) supplied from a high-temperature heat source (not shown) flows through the heat medium flow path 22b. Under the pressure conditions (relative pressure) thus realized, the adsorbate is desorbed by the second adsorbent of the second adsorber 22 based on the adsorption and desorption characteristics of the second adsorbent, and the desorbed adsorbate is condensed in the condenser 18. Then, the adsorbate condensed in the condenser 18 is supplied to the evaporator 12 through the pipe 25 by opening the on-off valve 21a.

C. First stage adsorber:
(C-1) Structure of the first adsorption device:
Fig. 2 is an explanatory diagram that typically illustrates the configuration of the first adsorption unit 20, and Fig. 3 is a perspective view that illustrates the schematic configuration of a tubular module 30 (more specifically, a heat transfer tube unit cell 50, described later, as an assembly of the tubular modules 30) housed in the reaction vessel 20a of the first adsorption unit 20. Note that Figs. 2 and 3, and Figs. 4 to 7 that will be described later, do not accurately illustrate the dimensional ratios of the various parts.

The first adsorber 20 is a multi-tube heat exchange type adsorber comprising a plurality (N) of tubular modules 30. The tubular module 30 comprises a heat transfer tube 32 formed in a cylindrical shape, through which a heat medium flows, and an adsorbent layer 34 containing a first adsorbent that adsorbs and desorbs an adsorbate. FIG. 3 shows three tubular modules 30 arranged closely among the plurality of tubular modules 30 included in the first adsorber 20. FIG. 3 also shows the cross section of the portion where the adsorbent layer 34 is formed exposed at the end of the tubular module 30. The heat transfer tube 32 is a tubular member made of a metal such as copper or a copper alloy, and the inside of the heat transfer tube 32 constitutes an in-tube flow path through which the heat medium flows. The thickness of the tube wall of the heat transfer tube 32 can be, for example, 0.5 to 2.0 mm. The in-tube flow path formed in the heat transfer tube 32 constitutes a part of the heat medium flow path 20b described above. In the first-stage adsorption process described above, the adsorbate vapor supplied to the first adsorbent 20 via the pipe 21 flows along the outer surface of the tubular module 30 and is adsorbed by the first adsorbate in the adsorbent layer 34.

4 is a perspective view showing an outline of the appearance of the tubular module 30, and FIG. 5 is an explanatory diagram showing an enlarged portion of the tubular module 30 surrounded by the dashed line α in FIG. 3. The adsorbent layer 34 is formed so as to cover the outer circumferential surface of the heat transfer tube 32, and FIG. 5 shows a structure in which a portion of the tubular module 30 is cut out so as to penetrate the heat transfer tube 32 and the adsorption layer 34 in the stacking direction of the heat transfer tube 32 and the adsorption layer 34. In FIG. 5, the cross section of each part is hatched. As shown in FIG. 5, the adsorbent layer 34 is formed by stacking a plurality of wire layers 36 on the outer wall of the heat transfer tube 32, in which linear members 35 formed in a line containing the first adsorbent are arranged in a certain direction, and between the wire layers 36 adjacent to each other in the stacking direction, the angles at which the linear members 35 are arranged are different, and they cross each other. That is, in each wire layer 36, the linear members 35 are formed so as to be wound in a spiral shape on the heat transfer tube 32 (see FIG. 4). In this embodiment, the angle at which the linear members 35 are arranged is the same for the linear members 35 that make up the same wire layer 36 and for the wire layers 36 that are stacked every other wire layer 36, and the linear members 35 are formed in a mesh shape throughout the adsorbent layer 34. FIG. 5 shows an example in which five wire layers 36 are provided. The angle at which the linear members 35 are arranged on the heat transfer tube 32 is not particularly limited, but can be, for example, 10° to 170° with respect to the central axis C of the heat transfer tube 32 (see FIG. 4), and it is sufficient that a mesh structure is formed by the wire layers 36 adjacent in the stacking direction.

In FIG. 5, the thickness of the adsorbent layer 34 is indicated as H (mm), and the wire diameter of the linear member 35 is indicated as w (mm). The thickness H of the adsorbent layer 34 may be greater than 0.5 mm and less than 4.0 mm. The wire diameter w of the linear member 35 may be greater than 0.05 mm and less than 0.6 mm. In this embodiment, the cross-sectional shape of the linear member 35 is a rectangle with approximately the same length and width, and the wire diameter w is the length of one side of the periphery of the rectangle in the cross-sectional shape. The thickness H of the adsorbent layer 34 and the wire diameter w of the linear member 35 will be described in detail later. If the number of stages of the linear layer 36 is n stages, the thickness H of the adsorbent layer 34 is expressed by the following formula (1).

H=w×n… (1)

Furthermore, the gap between adjacent linear members 35 constituting the same wire layer 36 is constant, and in Figures 4 and 5, the gap is indicated as a wire gap w _gap (mm). Such a gap formed between the linear members 35 arranged at a constant angle on the outer wall of the heat transfer tube 32 serves as a flow path for the vaporized adsorbate, i.e., the adsorbate adsorbed to the first adsorbent and the adsorbate desorbed from the first adsorbent. The wire gap w _gap can be set appropriately within a range of, for example, 50 µm to 2 mm.

6 and 7 are explanatory diagrams of a manufacturing method for the adsorbent layer 34 in the tubular module 30. In this manufacturing method, a material in the form of a paste made by adding a binder and a solvent to a mixture of a first adsorbent and a heat transfer assistant (carbon fiber, etc.) is used to form the shape of the adsorbent layer 34, for example, by a 3D printer.

Specifically, first, as shown in FIG. 6, the nozzle 40 is moved from one end 32a of the heat transfer tube 32 to the other end 32b of the heat transfer tube 32 (white arrow F32 in FIG. 6) while rotating the heat transfer tube 32 about the central axis C of the heat transfer tube 32 as the center of rotation (white arrow F41 in FIG. 6). The adsorbent forming material extruded from the discharge port of the moving nozzle 40 adheres to the outer wall surface of the heat transfer tube 32, forming a molded body disposed obliquely with respect to the central axis C as shown in FIG. 6. Such a molded body is also called a linear member intermediate body 35pr. After one linear member intermediate body 35pr is molded, another linear member intermediate body 35pr is molded in the same manner with a gap corresponding to the inter-wire gap w _gap . By repeating such an operation, a layer that becomes the first wire layer 36 is formed.

Next, as shown in Fig. 7, the nozzle 40 is moved from the other end 32b of the heat transfer tube 32 to one end 32a of the heat transfer tube 32 (white arrow F32 in Fig. 7) while rotating the heat transfer tube 32 around the central axis C of the heat transfer tube 32 as the center of rotation. The adsorbent forming material extruded from the discharge port of the moving nozzle 40 is adhered to the outer surface of the layer that will become the first-stage wire layer 36 described above, thereby forming a linear member intermediate body 35pr that is disposed obliquely with respect to the central axis C as shown in Fig. 7. After forming one linear member intermediate body 35pr, another linear member intermediate body 35pr is formed in the same manner with a gap corresponding to the wire gap w _gap . By repeating such an operation, a layer that will become the second-stage wire layer 36 is formed. As described above, each linear member intermediate 35pr constituting the layer that will become the second wire layer 36 is arranged at a different angle and intersects with each other compared to each linear member intermediate 35pr constituting the layer that will become the first wire layer 36.

The above-described operation of forming the layers that will become the wire layers 36 is repeated according to the number of wire layers 36 to be provided, and then the drying and firing processes are performed to complete the adsorbent layer 34. Each wire layer 36 may be formed by a plurality of wire member intermediates 35pr arranged to be spaced apart from each other as described above, or by winding a single wire member intermediate 35pr while shifting its position on the heat transfer tube 32.

(C-2) Linear diameter w of linear member and thickness H of adsorbent layer:
In this embodiment, the relationship between the wire diameter w of the linear members 35 and the thickness H of the adsorbent layer 34 is set to a specific relationship, thereby increasing the output VCP per unit volume of the first adsorption device 20 when the adsorbate is desorbed from the first adsorption device 20 (adsorption/desorption process). "Output VCP" refers to the amount of cold energy (cold energy output density) extracted per unit volume (1 L) of the first adsorption device 20, and is expressed in kW/L. As described above, the first adsorption device 20 in this embodiment is formed so that the wire diameter w (mm) of the linear members 35 satisfies the following formula (2), and the thickness H (mm) of the adsorbent layer 34 satisfies the following formula (3).

0.05<w<0.6...(2)
0.5<H<4.0...(3)

FIG. 8 is an explanatory diagram showing a contour map of the output VCP of the first adsorption device 20 with respect to the wire diameter w of the linear member 35 and the thickness H of the adsorbent layer 34. The output VCP shown in FIG. 8 was obtained by numerical analysis using a finite element method model in which the first adsorption device 20 having a multi-tube structure with a plurality of tubular modules 30 using one type of Al-MOF as the first adsorbent was divided into heat transfer tube unit cells 50 and the adsorbent layer 34 was divided into network structure unit cells 52. The "heat transfer tube unit cell 50" is a repeating unit constituting the multi-tube structure of the first adsorption device 20, and is composed of three tubular modules 30 as shown in FIG. 3. In FIG. 3, the distance between the tubular modules 30 is shown as the gap W _gap between the heat transfer tubes. The size of the gap W _gap between the heat transfer tubes is not particularly limited, but may be, for example, 1 mm or more from the viewpoint of easiness in ensuring assembly accuracy. From the viewpoint of preventing the heat pump from becoming large, the size of the gap W _gap between the heat transfer tubes may be, for example, 10 mm or less. Furthermore, in Fig. 3, the diameter of the tubular module 30 is shown as diameter D. Diameter D can be, for example, 10 to 40 mm. Furthermore, the "mesh structure unit cell 52" is a repeating unit that constitutes the mesh structure of the adsorbent layer 34, and has a structure shown in Fig. 5. Specifically, the mesh structure unit cell 52 has a structure in which a part of the tubular module 30 is taken out so as to penetrate through it in the thickness direction, and has a structure including a portion where the linear members 35 that constitute adjacent wire layers 36 cross each other in the stacking direction.

8 was calculated with the length L of the tubular module 30 set to 1800 mm, the gap W _gap between the heat transfer tubes set to 2 mm, the gap w _gap between the wires set to 0.3 mm, and the diameter D of the tubular module 30 set to 26 mm, the pressure of the first adsorption device 20 changed from 1500 Pa to 100 Pa, and the temperature inside the heat transfer tube 32 set to 15° C. Then, with respect to the network structure unit cell 52, the output VCP in the adsorption/desorption step in which the first adsorbent of the first adsorption device 20 was regenerated was calculated using the finite element method, taking into consideration the vapor diffusion of the adsorbate, the adsorption/desorption reaction, and heat transfer. Figure 8 shows three conditions, (w, H) = b (0.2, 1.0), a (0.2, 4.0), and c (0.6, 1.0), as the condition (condition b) under which VCP was maximized in the search range of the output VCP, the condition (condition a) under which the thickness H of the adsorbent layer 34 was greater than condition b, and the condition (condition c) under which the wire diameter w of the linear member 35 was greater than condition b.

Figure 9 is an explanatory diagram showing the adsorption amount distribution 10 seconds after the start of desorption in a network structure unit cell 52 that satisfies condition a, Figure 10 is an explanatory diagram showing the adsorption amount distribution 10 seconds after the start of desorption in a network structure unit cell 52 that satisfies condition b, and Figure 11 is an explanatory diagram showing the adsorption amount distribution 10 seconds after the start of desorption in a network structure unit cell 52 that satisfies condition c. (a) in Figure 9, (a) in Figure 10, and (a) in Figure 11 represent the range in which the adsorption amount is 0.2 to 0.3 (g/g), (b) in Figure 9, (b) in Figure 10, and (b) in Figure 11 represent the range in which the adsorption amount is 0.1 to 0.2 (g/g), and (c) in Figure 9, (c) in Figure 10, and (c) in Figure 11 represent the range in which the adsorption amount is 0.0 to 0.1 (g/g).

Figure 12 is an explanatory diagram showing the temperature distribution 10 seconds after the start of desorption in a network structure unit cell 52 that satisfies condition a, Figure 13 is an explanatory diagram showing the temperature distribution 10 seconds after the start of desorption in a network structure unit cell 52 that satisfies condition b, and Figure 14 is an explanatory diagram showing the temperature distribution 10 seconds after the start of desorption in a network structure unit cell 52 that satisfies condition c. (a) in Figure 12, (a) in Figure 13, and (a) in Figure 14 represent the temperature range of 10 to 15 (°C), (b) in Figure 12, (b) in Figure 13, and (b) in Figure 14 represent the temperature range of 5.0 to 10 (°C), and (c) in Figure 12, (c) in Figure 13, and (c) in Figure 14 represent the temperature range of 0.0 to 5.0 (°C).

8, when comparing conditions in which the wire diameter w of the linear member 35 is the same, there is a thickness H of the adsorbent layer 34 at which the output VCP is maximized. In this way, the thickness H at which the output VCP is maximized when the wire diameter w is the same is determined because the effect of increasing the output VCP due to the increase in the thickness H and the increase in the volume of the first adsorbent in the first adsorber 20, and the effect of decreasing the output VCP due to the increase in the thickness H and the increase in the heat transfer distance from the heat transfer tube 32 to the first adsorbent, which reduces the desorption rate, are balanced. When this is confirmed from the adsorption amount of the adsorbate shown in Figures 9 and 10 and the temperature distribution shown in Figures 12 and 13, it is confirmed that, for example, the adsorption amount at the upper end of the adsorbent layer 34 is greater under condition a than under condition b (see Figures 9 and 10), and the desorption of the adsorbate is slower. This is thought to be because the heat transfer distance from the heat transfer tube 32 to the first adsorbent is longer under condition a than under condition b, and the temperature at the upper end of the adsorbent layer 34 is lower (see Figures 12 and 13).

Also, as shown in condition b and condition c in FIG. 8, when comparing conditions in which the thickness H of the adsorbent layer 34 is the same, there is a wire diameter w of the linear member 35 at which the output VCP is maximum. In this way, the wire diameter w at which the output VCP is maximum when the thickness H is the same is determined because the effect of increasing the wire diameter w and increasing the volume of the first adsorbent in the first adsorber 20, thereby increasing the output VCP, and the effect of increasing the wire diameter w and increasing the diffusion distance of the adsorbate in the linear member 35, thereby delaying desorption inside the linear member 35, thereby decreasing the output VCP, are balanced. When this is confirmed from the adsorption amount of the adsorbate shown in FIG. 10 and FIG. 11 and the temperature distribution shown in FIG. 13 and FIG. 14, for example, the temperature of the adsorbent layer 34 is higher in condition c than in condition b (see FIG. 13 and FIG. 14), which is favorable for the desorption reaction. Nevertheless, it was confirmed that the amount of adsorption inside the linear member 35 was greater under condition c than under condition b (see Figures 10 and 11), and desorption was slower. From this, it is believed that the diffusion of the adsorbate inside the linear member 35 was rate-limiting under condition c compared to condition b, suppressing desorption.

Since the output VCP is affected by the thickness H and the wire diameter w as described above, in order to obtain a higher output VCP, the thickness H of the adsorbent layer 34 should be greater than 0.5 mm and less than 4.0 mm as shown in formula (2), and the wire diameter w of the wire member 35 should be greater than 0.05 mm and less than 0.6 mm as shown in formula (3). Here, in Fig. 8, the _gap W gap between the heat transfer tubes is 2 mm, the gap w _gap between the wires is 0.3 mm, and the diameter D of the tubular module 30 is 26 mm, but even if these conditions are different, the above-mentioned numerical ranges of the thickness H and the wire diameter w that are desirable for increasing the output VCP can be applied in the same way. This will be described below.

The output VCP can be expressed by the following formula (4). In formula (4), Q represents the cold output of the heat transfer tube unit cell 50, V represents the volume of the heat transfer tube unit cell 50, D represents the diameter of the tubular module 30, L represents the length of the tubular module 30, q represents the cold output of the network structure unit cell 52, W _gap represents the heat transfer tube gap which is the distance between adjacent tubular modules 30, and w _gap represents the wire gap which is the distance between adjacently arranged linear members 35 (see Figs. 3 and 5). The numerator in the second row of formula (4) below represents that the cold output of the heat transfer tube unit cell 50 is obtained by multiplying the cold output q of the network structure unit cell 52 by the number of network structure unit cells 52.

The above formula (4) can be further rewritten as the following formula (5).

Here, q is the cold output of the network structure unit cell 52 as described above, and is rate-determined by diffusion in the thickness direction of the adsorbent layer 34 and heat transfer in the thickness direction, so it is a function of the wire diameter w of the linear member 35 and the thickness H of the adsorbent layer 34, which are parameters related to the structure of the adsorbent layer 34, and is shown as q(w, H) in formula (5). In formula (5), F is a function that summarizes the other terms. In formula (5), the value of the function F, which changes depending on the gap w _gap between the wires, the diameter D of the tubular module 30, and the gap W _gap between the heat transfer tubes, can also be considered as a coefficient of VCP. Therefore, even if the gap w _gap between the wires, the diameter of the tubular module 30, and the gap W _gap between the heat transfer tubes change, the map of the output VCP relative to the wire diameter w and the thickness H of the adsorbent layer 34 changes in peak height (shifts in the height direction of the contour map), but it is considered that the overall tendency of the VCP to change does not change. In other words, even if the wire gap w _gap , the diameter of the tubular module 30, and the gap W _gap between the heat transfer tubes change, it is believed that the suitable numerical ranges for the wire diameter w and thickness H to ensure the output VCP will not change.

FIG. 15 is an explanatory diagram showing a contour map of the output VCP with respect to the wire diameter w and the thickness H of the adsorbent layer 34, obtained by changing the wire diameter w of the wire member 35 to 0.5 mm among the conditions according to FIG. 8, as an example. As shown in formula (5), FIG. 8, and FIG. 15, even if the _gap W gap between the heat transfer tubes, the _gap w gap between the wires, and the diameter D of the tubular module 30 are changed, in order to obtain a higher output VCP, the wire diameter w of the wire member 35 may be larger than 0.05 mm, and more preferably larger than 0.1. Moreover, the wire diameter w may be less than 0.6 mm, and more preferably less than 0.5 mm, and even more preferably less than 0.4 mm. Similarly, the thickness H of the adsorbent layer 34 may be larger than 0.5 mm, and more preferably greater than 0.8 mm. Moreover, the thickness H may be less than 4.0 mm, and more preferably less than 3.0 mm.

According to the first adsorber 20 of the present embodiment configured as described above, a plurality of wire layers 36 in which linear members 35 formed in a linear shape containing an adsorbent are arranged in a certain direction are stacked on the outer wall of the heat transfer tube 32, and the wire layers 36 adjacent to each other in the stacking direction have different angles at which the linear members 35 are arranged, and the adsorbent layers 34 are crossed. In this way, since the entire adsorbent layer 34 is formed in a mesh shape, the diffusion distance of the adsorbate in the first adsorbent included in the adsorbent layer 34 can be shortened to increase the diffusion speed of the adsorbate, and the utilization efficiency of the first adsorbent in the adsorbent layer 34 can be increased. In addition, since the adsorbent layer 34 is arranged in the circumferential direction on the outer wall of the cylindrically formed heat transfer tube 32 in the first adsorber 20, the heat transfer efficiency from the heat transfer tube 32 to the adsorbent layer 34 can be increased. Therefore, when the first adsorber 20 is used as the first-stage adsorber of an adsorption-type multistage heat pump, the efficiency of cold generation can be increased when the first adsorber 20 is caused to desorb the adsorbate.

Furthermore, according to this embodiment, by setting the wire diameter w of the linear member 35 and the thickness H of the adsorbent layer 34 to values that satisfy formulas (2) and (3), the output VCP can be increased and the efficiency of cold heat generation in the first adsorber 20 can be improved in the adsorption/desorption process. In other words, by setting the wire diameter w of the linear member 35 and the thickness H of the adsorbent layer 34 to values that satisfy formulas (2) and (3), the diffusion rate of the adsorbate vapor in the first adsorbent and the heat transfer in the first adsorbent can be ensured, and the efficiency of desorption in the first adsorbent can be improved.

The first adsorbent 20 as described above can be used as the first-stage adsorbent connected to the evaporator 12 in the heat pump 10, which is a multi-stage heat pump, and can be particularly effective in increasing the efficiency of cold generation. In the first-stage adsorbent of a multi-stage heat pump, for example, when a relatively low-temperature heat source is used to desorb the adsorbate in order to increase the energy efficiency of the entire heat pump, the degree of heat transfer in the adsorbent layer 34 can be the rate-limiting factor for desorption. In addition, when the relative pressure in the adsorption/desorption process that connects the first adsorbent 20 and the second adsorbent 22 is a relatively small value, such as 0.2 to 0.4 or less, the diffusion rate of the adsorbate vapor in the adsorbent layer 34 can be the rate-limiting factor for desorption. In the first adsorption device 20 of this embodiment, by setting the wire diameter w of the linear member 35 and the thickness H of the adsorption layer 34 within the numerical ranges described above, it is possible to more fully ensure both the diffusion rate of the adsorbate vapor in the first adsorption material and the heat transfer in the first adsorption material, and therefore, when used as a first-stage adsorption device, the efficiency of cold generation in the entire heat pump 10 can be further improved.

In particular, adsorbents that can be desorbed using a relatively low-temperature heat source, such as Al-MOF, are desirable as adsorbents for use in the first-stage adsorber; however, if the temperature of the heat source used during desorption is low, the diffusion rate of the adsorbate vapor in the adsorbent layer may be suppressed, and the efficiency of cold generation may be reduced. In the first adsorber 20 of this embodiment, the diffusion rate of the adsorbate vapor is increased by specifying the wire diameter w of the wire member 35 and the thickness H of the adsorbent layer 34, so that the efficiency of cold generation can be increased when using an adsorbent that can use a relatively low-temperature heat source, such as Al-MOF, to perform the desorption process using a low-temperature heat source.

D. Other embodiments:
In the embodiment described above, the linear members 35 constituting the adsorbent layer 34 of the first adsorption device 20 have a rectangular cross-sectional shape, but may have a different shape. For example, the linear members 35 may have a cross-sectional shape of a circle, an ellipse, a polygon, or the like.

In the above embodiment, the first adsorber 20 is a multi-tube heat exchange type adsorber, and has three or more tubular modules 30, with a heat transfer tube unit cell 50 consisting of three tubular modules 30 as a constituent unit, but a different configuration may be used. The number of tubular modules 30 provided in the first adsorber 20 may be a number other than three, or may be one.

In the above-described embodiment, the heat pump 10 is provided with two adsorption units, the first adsorption unit 14 and the second adsorption unit 16, which are connected in parallel between the evaporator 12 and the condenser 18, but a different configuration may be used. The number of adsorption units may be three or more, or may be one. If the configuration of the first adsorption unit 20 described in the embodiment is applied to the first-stage adsorption unit in the adsorption unit provided in the heat pump, the same effect as in the embodiment can be obtained.

The present disclosure is not limited to the above-mentioned embodiments, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each form described in the Summary of the Invention column can be replaced or combined as appropriate to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate.

REFERENCE SIGNS LIST 10... heat pump 12... evaporator 12a... storage vessel 12b... heat medium flow path 14... first adsorption section 16... second adsorption section 18... condenser 20... first adsorption device 20a... reaction vessel 20b... heat medium flow path 21, 23, 24, 25... piping 21a, 23a, 24a, 25a... on-off valve 22... second adsorption device 22a... reaction vessel 22b... heat medium flow path 30... tubular module 32... heat transfer tube 32a, 32b... end 34... adsorbent layer 35... wire member 35pr... wire member intermediate 36... wire layer 40... nozzle 50... heat transfer tube unit cell 52... mesh structure unit cell

Claims (5)

In an adsorption-type multistage heat pump in which a plurality of adsorbers are connected in series to an evaporator, a first-stage adsorber is connected to the evaporator,
a heat transfer tube formed in a cylindrical shape and having a heat medium flowing therethrough;
an adsorbent layer in which a plurality of wire layers are laminated on an outer wall of the heat transfer tube, the wire layers being layers in which linear members containing an adsorbent that adsorbs and desorbs an adsorbate are arranged in a fixed direction, the wire layers being arranged at different angles between adjacent wire layers in the lamination direction, and the wire layers intersect with each other;
Equipped with
The adsorbent is an aluminum-containing metal-organic framework (Al-MOF),
The wire diameter w of the linear member is greater than 0.05 mm and less than 0.6 mm;
The thickness H of the adsorbent layer is greater than 0.5 mm and less than 4.0 mm.
Suction device. The adsorber according to claim 1 ,
The suction unit, wherein a wire diameter w of the linear member is greater than 0.1 mm and less than 0.4 mm. The adsorber according to claim 1 or 2 ,
The thickness H of the adsorbent layer is greater than 0.8 mm and less than 3.0 mm. An adsorption-type multi-stage heat pump in which a plurality of adsorbers are connected in series to an evaporator,
An adsorption-type multistage heat pump comprising the adsorber according to claim 1 as a first stage adsorber connected to the evaporator. The adsorption type multi-stage heat pump according to claim 4 ,
The temperature during desorption of the adsorbate in the first stage adsorber is 10 to 15°C.

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